Minggu, 17 September 2017

Temperature & Humidity in a computer room or data center is critical to ensuring uptime and system reliability AMNIMARJESLOW GOVERNMENT 91220017 LCLAR LOR THUMBLERER LJBUSAF



                      Humidity in the Data Center: Do We Still Need to Sweat It?

                     Humidity in the data center 

Temperature is the hottest topic (pardon the pun) when it comes to maintaining the proper environmental conditions in a data center—particularly in the context of energy consumption and cost—but humidity is also important. But with ASHRAE’s recently expanded allowable and recommended ranges for temperature and humidity, is water vapor still a concern?

Humidity: What You Can’t See Can Hurt Your Data Center

Liquid water is generally a bad thing in your data center, but in the air, it’s something you need in the right proportions. Too much humidity can lead to condensation, which can in turn cause corrosion or—in sufficient amounts—electrical shorts. But too little humidity promotes buildup of electrostatic charge, and discharges of static electricity can damage or destroy sensitive electronics.
Part of the solution is data center measurement and monitoring. Installing humidity sensors (along with temperature sensors) provides information that enables maintaining proper environmental conditions. That’s clear enough. What’s not so clear is what exactly you should measure. Traditionally, relative humidity (RH) has been the metric of choice, with 45% to 55% RH being the espoused ideal range. But inherent difficulties with RH mean it is being used less frequently as a metric. Furthermore, the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) recently expanded its recommended and allowable temperature ranges—as well as its humidity ranges. Given, then, that the traditional view of maintaining 45% to 55% RH in the data center seems to be in flux, what’s the best approach?

Measuring Humidity: Absolute or Relative?

The difficulty with attempting to maintain a relative humidity in the data center is that RH is dependent on temperature: it is a measure of the percentage of water vapor content that air can hold at a given temperature. But because warmer air holds more water, an RH of, say, 50% at 65°F would be significantly lower than 50% at 80°F. The difficulty in the context of data centers is that these facilities deal with both warm air and cool air, which are ideally kept as separate as possible. Cool air flows into a server inlet, is heated and then is ejected as warm exhaust. The water content of this air hasn’t changed during this process (barring, of course, condensation), but the relative humidity of the exhaust is lower than that of the cool air at the server inlet.
An alternative to relative humidity is absolute humidity, which can be expressed as, for instance, the mass of water per mass of dry air. A more familiar measure of absolute humidity is the dew point: the temperature at which water in the air begins condensing (or the temperature at which the RH is 100% for a given air mass). The advantage of measuring and monitoring dew point temperatures instead of relative humidity is that the dew point at the server inlet is the same as that at the server exhaust outlet. A sensor can thus be placed at the server inlet (or the outlet) without the need to worry about getting a humidity measurement at the outlet as well.
Naturally, then, measuring absolute humidity enables companies to have less of a “moving target”  with regard to maintaining a specific humidity in their data centers. Furthermore, the recently updated ASHRAE temperature and humidity ranges show a clear recognition of absolute humidity as being important—not just relative humidity.

Expanded ASHRAE Guidelines

A recent whitepaper from The Green Grid  discusses the new ASHRAE recommended and allowable ranges in the context of free cooling. Over the recommended temperature range (18°C to 27°C, or about 64°F to 81°F), a portion (temperatures below about 23°C or about 73°F) has a corresponding maximum humidity of 50% (RH). The other portion has a maximum absolute humidity of about 0.011 (measured in grams of water per grams of dry air). The previous (2004) ASHRAE recommended range maintained the traditional RH values of 40% to 55%.
Interestingly, however, the new ASHRAE guidelines still maintain the same overall humidity range—although the recommended humidity varies to some extent with temperature, the absolute humidity should never fall below about 0.006 (same units as above), nor should it ever exceed 0.011. For certain allowable ASHRAE ranges (which should only be used when the data center’s IT equipment can withstand them), the absolute and relative humidity can go beyond the recommended range. Not only do these expanded guidelines give data center operators more leeway with their cooling infrastructure, they also enable more use of free cooling (air-side or water-side economization)—in many areas of the world, throughout the entire year.

Should You Worry About Humidity?

The wider ASHRAE guidelines mean that facilities do not need to sweat humidity as much as they did when 40% to 55% RH was the rule. Furthermore, a growing recognition of absolute humidity (such as dew point) as a better metric means less measurement variation from one side the server (the inlet) to the other (the exhaust outlet). Of course, humidity is still a concern: too much or too little can still cause problems for your IT equipment.
Maintaining a certain humidity range when using mechanical cooling methods often requires addition of (or removal of) water from the air, but this generally involves a fairly closed system. When free cooling is used extensively, the natural variations in temperature and humidity of outside air can complicate the situation, simply by making humidifiers work harder, for instance. Just “opening the windows” of your facility sounds like a great cooling option (it’s certainly cheap), but doing so on particularly rainy or dry days can wreak havoc on your equipment, unless you take steps to regulate water content in the air.

Conclusions

So, should you still sweat humidity in the data center? In some sense, yes: too much or too little water vapor in the air is problematic—nothing about that situation has changed. But as the expanded ASHRAE recommended and allowable operating ranges indicate, many companies and manufacturers are recognizing that the old, tight limits on temperature and humidity are not as necessary as once thought. Thus, although maintaining proper humidity is still critical, it’s not as difficult as it once was (thought to be).
Perhaps the more important industry trend to note is the shift from relative humidity toward absolute humidity as the superior metric. Absolute humidity is just that—absolute, in the sense that it is a measurement of the actual water content of air. Relative humidity measures the percent capacity of air at a given temperature, which can be problematic, because data centers deal with cool air and warm air simultaneously. The current challenge for most facilities is selecting the right temperature and humidity range—whether the recommended range or an allowable range—to maximize the potential for free cooling while still adequately protecting equipment from heat and condensation. So—stay cool and dry, but keep an eye on your energy usage while you’re at it.



Recommended Computer Room Temperature
Operating expensive IT computer equipment for extended periods of time at high temperatures greatly reduces reliability, longevity of components and will likely cause unplanned downtime. Maintaining an ambient temperature range of 68° to 75°F (20° to 24°C) is optimal for system reliability. This temperature range provides a safe buffer for equipment to operate in the event of air conditioning or HVAC equipment failure while making it easier to maintain a safe relative humidity level.
It is a generally agreed upon standard in the computer industry that expensive IT equipment should not be operated in a computer room or data center where the ambient room temperature has exceeded 85°F (30°C).
In today’s high-density data centers and computer rooms, measuring the ambient room temperature is often not enough. The temperature of the air where it enters the server can be measurably higher than the ambient room temperature, depending on the layout of the data center and a higher concentration of heat producing equipment such as blade servers. Measuring the temperature of the aisles in the data center at multiple height levels can give an early indication of a potential temperature problem. For consistent and reliable temperature monitoring, place a temperature sensor at least every 25 feet in each aisle with sensors placed closer together if high temperature equipment like blade servers are in use. We recommend installing Tem PageR, Room Alert 7E or Room Alert 11E rack units at the top of each rack in the data center. As the heat generated by the components in the rack rises, TemPageR and Room Alert units will provide an early warning and notify staff for temperature issues before critical systems, servers or network equipment is damaged.
Recommended Computer Room Humidity
Relative humidity (RH) is defined as the amount of moisture in the air at a given temperature in relation to the maximum amount of moisture the air could hold at the same temperature. In a data center or computer room, maintaining ambient relative humidity levels between 45% and 55% is recommended for optimal performance and reliability.
When relative humidity levels are too high, water condensation can occur which results in hardware corrosion and early system and component failure. If the relative humidity is too low, computer equipment becomes susceptible to electrostatic discharge (ESD) which can cause damage to sensitive components. When monitoring the relative humidity in the data center, we recommend early warning alerts at 40% and 60% relative humidity, with critical alerts at 30% and 70% relative humidity. It is important to remember that the relative humidity is directly related to the current temperature, so monitoring temperature and humidity together is critical. As the value of IT equipment increases, the risk and associated costs can increase exponentially. 


Effect of humidity on electronic devices

Problem of mould caused due to surrounding humidity
Humidity is one of the factors with heat that causes trouble in the controlling machine. How does humidity affect the controlling machine is considered below.
There are plurality of joint parts in controlling machine. Humidity is the great enemy of joint parts. Graph shows “relationship between corrosion and humidity”. It is understood that corrosion progresses rapidly when humidity exceeds 60%. Humidity of about 70% is the common level in Japan and therefore, countermeasures for humidity are extremely important in controlling machine. Moreover, corrosion progresses as temperature increases and countermeasures for heat must also be simultaneously considered along with countermeasures for humidity.
Problem of mould caused due to surrounding humidity

Ion migration
Ion migration is the phenomenon wherein metal ions are eluted from its surface when voltage is applied to metal when water molecules contained in air adhere to metal surface.
When ion migration progresses, there is danger of short circuit due to adjacent conductor(metal). Moreover, in most of the cases, circuit gets burnt by large current that flows at the instant when it makes contact with the conductor flowing, causing trouble of non-regeneration.
Ion migration
Water molecules contained in air adhere to the solid surface and form a thin film of water on the surface.
Ion migration
Solid (metal) surface to which voltage is applied, starts eluting as metal ions in this (abovementioned) state.
Ion migration
Metal eluted as ions are pulled by neighbouring conductor.
Ion migration
Metal film acts as a bridge between the conductors, causing short circuit thereby becoming a cause for failure.
*In most cases, the metal film is formed in dendrite shape and evaporates and disappears at the time of short circuit as it is very brittle. Therefore, failure by ion migration is a cumbersome condition which is not reproduced after occurrence.



                                                       Humidity and Computers 

Environmental conditions – especially humidity – can directly affect the functioning and performance of computers…


A high level of humidity can cause internal components of PCs to rust and degrade some of their essential properties, such as electrical resistance or thermal conductivity. Under extreme conditions, humidity can cause computers to short-circuit, resulting in effects ranging from loss of data to physical damage of some system components.  This situation can be aggravated further when computers are in environments that are not climate controlled such as warehouses or areas on industrial floors where other chemical vapours may be mixing with the humidity and becoming corrosive.
Computers are usually used in environments with an acceptable level of relative humidity, such as offices where conditions are controlled through air-conditioning systems. However, the same cannot be said for mobile devices or laptop computers, which can sometimes be exposed to extreme conditions. One of the most common problems is liquid getting into computers from rain, water splashed on a laptop when using it at the beach or near a swimming pool, or drinks that are accidentally spilled on them.
However, humidity can also condense inside the computer without the user realizing. This often happens when the computer is exposed to brusque changes in temperature. A typical example is when a computer is used in an air-conditioned office immediately after being transported in a vehicle exposed to direct sunlight.  The same effect happens when walking for a distance outside during the winter, and then bringing the computer into a warm office – A thin film of condensation could be covering the entire interior of the laptop.
The basic measures to take in order to prevent excess humidity that can damage PCs include not using computers near liquids or where liquid can be splashed on them and not exposing them to extreme humidity. Similarly, it is also advisable to avoid brusque changes in temperature and wait for your equipment to adapt to their new conditions before switching them on. Relative humidity levels between 45% and 60% are best for computing environments. Laptops may be able to go to a more extreme 30%-80%, but never use a computer beside or near an actual humidifier .



What is a Humidity / Dew Sensor?

A humidity sensor (or hygrometer) senses, measures and reports the relative humidity in the air. It therefore measures both moisture and air temperature. Relative humidity is the ratio of actual moisture in the air to the highest amount of moisture that can be held at that air temperature. The warmer the air temperature is, the more moisture it can hold. Humidity / dew sensors use capacitive measurement, which relies on electrical capacitance. Electrical capacity is the ability of two nearby electrical conductors to create an electrical field between them. The sensor is composed of two metal plates and contains a non-conductive polymer film between them. This film collects moisture from the air, which causes the voltage between the two plates to change. These voltage changes are converted into digital readings showing the level of moisture in the air. 

 Adafruit Si7021 Temperature & Humidity Sensor Breakout Board  

This lovely sensor for Silicon labs has ± 3% relative humidity measurements with a range of 0–80% RH, and ±0.4 °C temperature accuracy at a range of -10 to +85 °C. Great for all of your environmental sensing projects. It uses I2C for data transfer so it works with a wide range of microcontrollers.
We put this nice sensor on a breakout board with a 3.3V regulator and level shifting so you can use it safely with 3.3V or 5V power & logic. There's a PTFE filter to keep the sensor clean, that's the white flat thing on top. Also comes with some pin header. Some light soldering is required to attach the header but it's easy to do.

               Hasil gambar untuk temperature and humidity electronic 


 
                             Hasil gambar untuk temperature and humidity electronic  
 
                                                             Hasil gambar untuk temperature and humidity electronic     
 

Temperature and humidity design criteria

Use these temperature and humidity design criteria to ensure that your data center environment provides optimal conditions for your server operation.
The information technology equipment can tolerate a considerable range of temperature and humidity, as described in the server specifications for each server. Generally, the air conditioning system should be designed for 22 degrees C (71.6 degrees F) and 45 percent relative humidity at altitudes up to 2150 m (7000 ft.). This design point provides for the largest buffer in terms of available system time. If the air conditioning system fails or malfunctions, the computer will be able to operate until it reaches its specified limits. This buffer provides additional time for air conditioning repairs before the computer must be shut down. The design point has also been proven to be a generally acceptable personal comfort level.
The design points for temperature and relative humidity might differ in certain geographical areas.
Air conditioning control instruments that respond to + or - 1 degree C ( + or - 2 degrees F) temperature and + or - 5 percent relative humidity should be installed.
Computer room cooling is basically a sensible (as opposed to a latent) cooling operation. (Sensible heat is defined as the transfer of thermal energy to or from a substance resulting in a change in temperature: Latent heat is the thermal energy absorbed or evolved in a process other than change of temperature.)
Substantial deviations from the recommended design point in either direction, if maintained for long periods (that is, for hours), will expose the system to malfunction from external conditions. For example, high relative humidity levels might cause improper feeding of paper, operator discomfort, and condensation on windows and walls when outside temperatures fall below room dew point.
Low relative humidity levels alone will not cause static discharge. However, in combination with many types of floor construction, floor coverings, and furniture, static charges that are generated by movement of people, carts, furniture, and paper will be more readily stored on one or more of the objects. These charges might be high enough to be objectionable to operating personnel, if discharged by contact with another person or object. If discharged to or near information technology equipment or other electronic equipment, these charges can cause intermittent interference. In most areas, it will be necessary to add moisture to the room air to meet the design criteria.
Because temperature or relative humidity deviations for only a few hours will cause the floors, desks, furniture, cards, tapes, and paper to reach a condition that will readily permit the retention of a charge, it is recommended that the air conditioning system be automatically controlled and provided with a high or low alarm or a continuous recording device with the appropriate limits marked.
Server operating limits
Some individual servers might require special consideration and have more or less restrictive requirements. See your server specifications for specific environmental limits.
The typical server operating environment is shown in the following table. The server nonoperating limits are shown in the following Nonoperating Server Limits table.
Table 1. Typical server operating environment
Environmental criteriaComputer room limitsOffice space air conditionedOffice space not air conditioned
Temperature16 to 32 degrees C (60.8 to 89.6 degrees F)16 to 32 degrees C (60.8 to 89.6degrees F)10.0 to 40.6 degrees C (50 to 105.08 degrees F)
Relative humidity20 to 80 percent8 to 80 percent8 to 80 percent
Maximum wet bulb23 degrees C (73.4 degrees F)23 degrees C (73.4 degrees F)27.0 degrees C (80.6 degrees F)
The design criteria is shown is the following table.
Table 2. Design criteria
Environmental criteriaDesign criteria
Temperature22 degrees C (71.6 degrees F)
Relative humidity45 percent
Maximum wet bulb23 degrees C (73.4 degrees F)
The recommended design is shown in the following figure.
Figure 1. Recommended design
Recommended design
Note
The air entering the server must be at the conditions for operation before power is turned on. Under no circumstances may the server's input air, room air, or humidity exceed the upper limit of the operating conditions. This is the maximum operating temperature limit and should not be considered a design condition. Also, the relative humidity of the air entering the server should not be greater than 80 percent. This specification is an absolute maximum. The optimum condition is where the room is at the design criteria of 22 degrees C (71.6 degrees F) and 45 percent humidity.
Air temperature in a duct or an underflow air supply should be kept above the room dew point temperature to prevent condensation within or on the servers. When it is necessary to add moisture to the system for control of low relative humidity, one of the following methods should be used:
  • Steam grid or jets
  • Evaporation pan or pane
  • Steam cup
  • Water atomizers
Water treatment might be necessary in areas with high mineral content to avoid contamination of the air.
Note
In localities where the outside temperature drops below freezing, condensation will form on single, glazed window panes. Also, if outside temperatures are considerably below freezing, the outside walls of the building should be waterproofed or vapor sealed on the inside or, in time, structural damage will occur in the outside walls.
Server nonoperating limits
When the facilities are shut down, the nonoperating environmental specifications must be followed to prevent damage to the server and to ensure reliable operation when power is restored.
Table 3. Nonoperating server limits
 Server nonoperating limits
Temperature10 to 43 degrees C (50 to 109.4 degrees F)
Relative humidity8 to 80 percent
Maximum wet bulb27 degrees C (80.6 degrees F)                      
 

 
  
Humidity and ESD Control

 
 INTRODUCTION
The control of electrostatic discharge can easily be implemented by employing basic control practices and principles in conjunction with the proper control products. Establishing an ESD Control program is dependent on the components that need protecting, the specifications of the internal quality control program and both the manufacturer and customer's requirements. What is often overlooked are the inherent environmental conditions and their control, i.e., humidity, temperature, pressure, number of air borne particles and air recirculation. The most significant environmental factor in ESD Control is the relative humidity (RH).
 
 EFFECTS OF HUMIDITYIn very dry areas, humidification is desirable because it makes antistatic materials with "sweat layers" function better as well as an overall reduction (not elimination) in triboelectric charging for all materials. Do not let high humidity levels build a false confidence, and beware of corrosion problems with interconnects and other electrical interfaces.
A high relative humidity, over 30% RH, reduces the resistance of most dielectrics resulting in an increase in return current, which is the current that opposes a charge buildup. When an object is undergoing tribocharging in a high humidity environment, the object will reach an equilibrium point where the tribocharging current equals the return current. For objects that undergo charging to a high potential, the primary impact of humidity is to encourage or discourage corona, and effect the rise time of the discharge current.
Normally, the moisture content in the air tends to lower the surface resistance of floors, carpets, table mats, etc., by letting wet particles create a vaguely conductive (or less than 10-9 Ohms/square) film over an otherwise insulating surface. If the relative humidity decreases, this favorable phenomenon disappears.
The air itself, being dry, becomes a part of the electrostatic build-up mechanism every time there is an air flow (wind, air conditioning, blower) passing over an insulated surface.
Table I
Tribocharging and Relative Humidity (RH)
(Reference 4)

ACTIVITY (@ 70° F)
STATIC VOLTAGES
20 % RH
80% RH
Walking across vinyl floor
12 kV
250 V
Walking across synthetic carpet
35 kV
1.5 kV
Arising from foam cushion
18 kV
1.5 kV
Picking up polyethylene bag
20 kV
600 V
sliding styrene box on carpet
18 kV
1.5 kV
Removing Mylar tape from PC board
12 kV
1.5 kV
Shrinkable film on PC board
16 kV
3 kV
Triggering vacuum solder remover
8 kV
1 kV
Aerosol circuit freeze spray
15 kV
5 kV
As Table 1 above shows, triboelectric charging persists even at high relative humidity. The fact remains that triboelectric charging becomes troublesome below 20 to 30% relative humidity, as shown by the high voltages attained at 20% RH in the Table 1. According to Koyler ET. Al. [1], Relative humidity values should include an associated temperature because a temperature factor is involved in surface resistivity.    MIL-HDBK-263 Standard Humid air helps to dissipate electrostatic charges by keeping surfaces moist, therefore increasing surface conductivity. Substantial electrostatic voltage levels can accumulate with a decrease in relative humidity, see Table 1 above. However, it is also evident from Table 1 that significant electrostatic voltages can still be generated with relative humidity as high as 90 percent. Relative humidity between 40 percent and 60 percent in ESD protective areas is desirable as long as it does not result in corrosion or in other detrimental effects such as PWB delamination during soldering. Where high relative humidity levels cannot be maintained, ionized air can be used to dissipate electrostatic charges.
MIL-STD-1695 specifically addresses relative humidity levels in the range of 30 - 70 percent in areas where electronic parts and hybrid microcircuits (MIL-STD-1695, bwork areas 5 and 6) are handled or processed. MIL-STD-1695 requires the same level of relative humidity controls for handling and storage areas (MIL-STD-1695, work area 13), except when items are covered or protected.
 CONCLUSION Humidity control does limit the triboelectric charging process, but does not eliminate any of the conventional safeguards; it is strictly a backup or "safety net" measure. Also, humidity control may give personnel a false sense of security and cause a relaxation of operator disciplines, thus lowering overall ESD safety. Humidity control is also expensive and can cause corrosion or other adverse side effects. Humidity control is a backup that should be implemented only after careful consideration of benefits vs. cost and hazards. Humidification to 30 or 40% relative humidity, minimum, at 70° F, is surely desirable, but drawbacks include (1) expense of facilities for adding water to the air, (2) possible adverse effects such as delamination of polyamide circuit-board laminates or corrosion of metals if the humidity becomes too high, (3) the psychological factor of false confidence inspired in operators and even engineers, and (4) personnel discomfort. An ESD control program should still be employed using conventional grounding, shielding, ionization, and training products and techniques.  


Best humidity level for electronic shops?

        
 
What is the best humidity level for an electronic shop? On one end of the scale, you will have problems from corrosion due to high humidity and condensation, but at the other end there will be serious problems from ESD.
I've worked in shops at either extreme end of the scale, and would imagine the ideal level being around 50% relative humidity. Thoughts?
 
Just working with grounded wrist-straps, and keeping major ESD generating clutter to a minimum, you shouldn't have much problem down to about 40% relative humidity. However, below 35% or 40%, you should start being extra vigilant.
For example, it's always a good idea to keep styro foam packing material, wool sweaters, polyester fleeces, and rolls of packing tape away from your ESD-safe work area, but when the humidity is very low, even ordinary paper can start to be a problem. An ordinary laminated surface that might be passable at high humidity can start to cause problems when the air gets very dry. The professionals use grounded mats on the workbench surface all the time. When the air is very dry, ionizing fans become necessary.
So, you can work with almost any R.H., depending on the level of protection measures you have in place. 
 
 
 
 
                                                   Humidity  
 
Humidity is the amount of water vapor present in the air. Water vapor is the gaseous state of water and is invisible to the human eye.[1] Humidity indicates the likelihood of precipitation, dew, or fog. Higher humidity reduces the effectiveness of sweating in cooling the body by reducing the rate of evaporation of moisture from the skin. This effect is calculated in a heat index table or humidex. The amount of water vapor that is needed to achieve saturation increases as the temperature increases. As the temperature of a parcel of water becomes lower it will eventually reach the point of saturation without adding or losing water mass. The differences in the amount of water vapor in a parcel of air can be quite large. For example, a parcel of air that is near saturation may contain 28 grams of water per cubic meter of air at 30 °C, but only 8 grams of water per cubic meter of air at 8 °C.
There are three main measurements of humidity: absolute, relative and specific. Absolute humidity is the water content of air expressed in gram per cubic meter.[2] Relative humidity, expressed as a percent, measures the current absolute humidity relative to the maximum (highest point) for that temperature. Specific humidity is the ratio of the mass of water vapor to the total mass of the moist air parcel. 

      
                         Humidity and hygrometry
                                 Cloud forest mount kinabalu.jpg   

  

Types

Paranal Observatory on Cerro Paranal in the Atacama Desert is one of the driest places on earth.

Absolute humidity

Absolute humidity is the total mass of water vapor present in a given volume of air. It does not take temperature into consideration. Absolute humidity in the atmosphere ranges from near zero to roughly 30 grams per cubic meter when the air is saturated at 30 °C (86 °F).[4]
Absolute humidity is the mass of the water vapor , divided by the volume of the air and water vapor mixture , which can be expressed as:
The absolute humidity changes as air temperature or pressure changes. This makes it unsuitable for chemical engineering calculations, e.g. for clothes dryers, where temperature can vary considerably. As a result, absolute humidity in chemical engineering may refer to mass of water vapor per unit mass of dry air, also known as the mass mixing ratio (see "specific humidity" below), which is better suited for heat and mass balance calculations. Mass of water per unit volume as in the equation above is also defined as volumetric humidity. Because of the potential confusion, British Standard BS 1339 (revised 2002) suggests avoiding the term "absolute humidity". Units should always be carefully checked. Many humidity charts are given in g/kg or kg/kg, but any mass units may be used.
The field concerned with the study of physical and thermodynamic properties of gas–vapor mixtures is named psychrometrics.

Relative humidity

The relative humidity or of an air-water mixture is defined as the ratio of the partial pressure of water vapor in the mixture to the equilibrium vapor pressure of water over a flat surface of pure water[5] at a given temperature:
Relative humidity is normally expressed as a percentage; a higher percentage means that the air-water mixture is more humid.
Relative humidity is an important metric used in weather forecasts and reports, as it is an indicator of the likelihood of precipitation, dew, or fog. In hot summer weather, a rise in relative humidity increases the apparent temperature to humans (and other animals) by hindering the evaporation of perspiration from the skin. For example, according to the Heat Index, a relative humidity of 75% at air temperature of 80.0 °F (26.7 °C) would feel like 83.6 °F ±1.3 °F (28.7 °C ±0.7 °C).[8][9]

Specific humidity

Specific humidity (or moisture content) is the ratio of the mass of water vapor to the total mass of the moist air parcel.[10] Specific humidity is approximately equal to the "mixing ratio", which is defined as the ratio of the mass of water vapor in an air parcel to the mass of dry air for the same parcel. As temperature decreases, the amount of water vapor needed to reach saturation also decreases. As the temperature of a parcel of air becomes lower it will eventually reach the point of saturation without adding or losing water mass. The differences in the amount of water vapor in a parcel of air can be quite large, for example; A parcel of air that is near saturation may contain 28 grams of water per cubic meter of air at 30 °C, but only 8 grams of water per cubic meter of air at 8 °C.

Measurement

A device used to measure humidity is called a psychrometer or hygrometer. A humidistat is a humidity-triggered switch, often used to control a dehumidifier.
There are various devices used to measure and regulate humidity. Calibration standards for the most accurate measurement include the gravimetric hygrometer, chilled mirror hygrometer, and electrolytic hygrometer. The gravimetric method, while the most accurate, is very cumbersome. For fast and very accurate measurement the chilled mirror method is effective.[11]
Humidity is also measured on a global scale using remotely placed satellites. These satellites are able to detect the concentration of water in the troposphere at altitudes between 4 and 12 kilometers. Satellites that can measure water vapor have sensors that are sensitive to infrared radiation. Water vapor specifically absorbs and re-radiates radiation in this spectral band. Satellite water vapor imagery plays an important role in monitoring climate conditions (like the formation of thunderstorms) and in the development of weather forecasts.

Climate

While humidity itself is a climate variable, it also interacts strongly with other climate variables. The humidity is affected by winds and by rainfall.
The most humid cities on earth are generally located closer to the equator, near coastal regions. Cities in South and Southeast Asia are among the most humid. Kuala Lumpur, Jakarta, and Singapore have very high humidity all year round because of their proximity to water bodies and the equator and often overcast weather. Some places experience extreme humidity during their rainy seasons combined with warmth giving the feel of a lukewarm sauna, such as Kolkata, Chennai and Cochin in India, and Lahore in Pakistan. Sukkur city located on the Indus River in Pakistan has some of the highest and most uncomfortable dew point in the country frequently exceeding 30 °C (86 °F) in the Monsoon season.[12] High temperatures couple up with bizarre dew point to create heat index in excess of 65 °C (149 °F). Darwin, Australia experiences an extremely humid wet season from December to April. Shanghai and Hong Kong in China also have an extreme humid period in their summer months. During the South-west and North-east Monsoon seasons (respectively, late May to September and November to March), expect heavy rains and a relatively high humidity post-rainfall. Outside the monsoon seasons, humidity is high (in comparison to countries North of the Equator), but completely sunny days abound. In cooler places such as Northern Tasmania, Australia, high humidity is experienced all year due to the ocean between mainland Australia and Tasmania. In the summer the hot dry air is absorbed by this ocean and the temperature rarely climbs above 35 °C (95 °F).

United States

In the United States the most humid cities, strictly in terms of relative humidity, are Forks and Olympia, Washington.[13] This fact may come as a surprise to many, as the climate in this region rarely exhibits the discomfort usually associated with high humidity. This is because high dew points play a more significant role than relative humidity in discomfort, and so the air in these western cities usually does not feel "humid" as a result. In general, dew points are much lower in the Western U.S. than those in the Eastern U.S.
The highest dew points in the US are found in coastal Florida and Texas. When comparing Key West and Houston, two of the most humid cities from those states, coastal Florida seems to have the higher dew points on average. However, Houston lacks the coastal breeze present in Key West, and, as a much larger city, it suffers from the urban heat island effect.[14] A dew point of 88 °F (31 °C) was recorded in Moorhead Minnesota on July 19, 2011, with a heat index of 133.5, although dew points over 80 °F (27 °C) are rare there.[15] The US city with the lowest annual humidity is Las Vegas, Nevada, averaging 39% for a high and 21% as a low.[16] Appleton, Wisconsin registered a dew point of 90 degrees F on 13 July 1995 with an air temperature of 104 degrees resulting in a heat index of 149 degrees; this record has apparently held and in fact the highest dew point measured in the country bounced amongst or was tied by locations in Wisconsin, Minnesota, and Iowa during the preceding 70 years or more with locations in northern Illinois also coming close. Dew points of 95 degrees are found on the Red Sea coast of Saudi Arabia at certain times.

Global climate

Humidity affects the energy budget and thereby influences temperatures in two major ways. First, water vapor in the atmosphere contains "latent" energy. During transpiration or evaporation, this latent heat is removed from surface liquid, cooling the earth's surface. This is the biggest non-radiative cooling effect at the surface. It compensates for roughly 70% of the average net radiative warming at the surface.
Second, water vapor is the most abundant of all greenhouse gases. Water vapor, like a green lens that allows green light to pass through it but absorbs red light, is a "selective absorber". Along with other greenhouse gases, water vapor is transparent to most solar energy, as you can literally see. But it absorbs the infrared energy emitted (radiated) upward by the earth's surface, which is the reason that humid areas experience very little nocturnal cooling but dry desert regions cool considerably at night. This selective absorption causes the greenhouse effect. It raises the surface temperature substantially above its theoretical radiative equilibrium temperature with the sun, and water vapor is the cause of more of this warming than any other greenhouse gas.
Unlike most other greenhouse gases, however, water is not merely below its boiling point in all regions of the Earth, but below its freezing point at many altitudes. As a condensible greenhouse gas, it precipitates, with a much lower scale height and shorter atmospheric lifetime- weeks instead of decades. Without other greenhouse gases, Earth's blackbody temperature, below the freezing point of water, would cause water vapor to be removed from the atmosphere. Water vapor is thus a "slave" to the non-condensible greenhouse gases.

Air density and volume

Humidity depends on water vaporization and condensation, which, in turn, mainly depends on temperature. Therefore, when applying more pressure to a gas saturated with water, all components will initially decrease in volume approximately according to the ideal gas law. However, some of the water will condense until returning to almost the same humidity as before, giving the resulting total volume deviating from what the ideal gas law predicted. Conversely, decreasing temperature would also make some water condense, again making the final volume deviate from predicted by the ideal gas law. Therefore, gas volume may alternatively be expressed as the dry volume, excluding the humidity content. This fraction more accurately follows the ideal gas law. On the contrary the saturated volume is the volume a gas mixture would have if humidity was added to it until saturation (or 100% relative humidity).
Humid air is less dense than dry air because a molecule of water (M ≈ 18 u) is less massive than either a molecule of nitrogen (M ≈ 28) or a molecule of oxygen (M ≈ 32). About 78% of the molecules in dry air are nitrogen (N2). Another 21% of the molecules in dry air are oxygen (O2). The final 1% of dry air is a mixture of other gases.
For any gas, at a given temperature and pressure, the number of molecules present in a particular volume is constant – see ideal gas law. So when water molecules (vapor) are introduced into that volume of dry air, the number of air molecules in the volume must decrease by the same number, if the temperature and pressure remain constant. (The addition of water molecules, or any other molecules, to a gas, without removal of an equal number of other molecules, will necessarily require a change in temperature, pressure, or total volume; that is, a change in at least one of these three parameters. If temperature and pressure remain constant, the volume increases, and the dry air molecules that were displaced will initially move out into the additional volume, after which the mixture will eventually become uniform through diffusion.) Hence the mass per unit volume of the gas—its density—decreases. Isaac Newton discovered this phenomenon and wrote about it in his book Opticks.

Effects

Animals and plant

Humidity is one of the fundamental abiotic factors that defines any habitat, and is a determinant of which animals and plants can thrive in a given environment.[24]
The human body dissipates heat through perspiration and its evaporation. Heat convection, to the surrounding air, and thermal radiation are the primary modes of heat transport from the body. Under conditions of high humidity, the rate of evaporation of sweat from the skin decreases. Also, if the atmosphere is as warm as or warmer than the skin during times of high humidity, blood brought to the body surface cannot dissipate heat by conduction to the air, and a condition called hyperthermia results. With so much blood going to the external surface of the body, less goes to the active muscles, the brain, and other internal organs. Physical strength declines, and fatigue occurs sooner than it would otherwise. Alertness and mental capacity also may be affected, resulting in heat stroke or hyperthermia.

Human comfort

Humans are sensitive to humid air because the human body uses evaporative cooling as the primary mechanism to regulate temperature. Under humid conditions, the rate at which perspiration evaporates on the skin is lower than it would be under arid conditions. Because humans perceive the rate of heat transfer from the body rather than temperature itself, we feel warmer when the relative humidity is high than when it is low.
Some people experience difficulty breathing in humid environments. Some cases may possibly be related to respiratory conditions such as asthma, while others may be the product of anxiety. Sufferers will often hyperventilate in response, causing sensations of numbness, faintness, and loss of concentration, among others.[25]
Air conditioning reduces discomfort in the summer not only by reducing temperature, but also by reducing humidity. In winter, heating cold outdoor air can decrease relative humidity levels indoor to below 30%,[26] leading to discomfort such as dry skin, cracked lips and excessive thirst.

Electronics

Many electronic devices have humidity specifications, for example, 5% to 45%. At the top end of the range, moisture may increase the conductivity of permeable insulators leading to malfunction. Too low humidity may make materials brittle. A particular danger to electronic items, regardless of the stated operating humidity range, is condensation. When an electronic item is moved from a cold place (e.g. garage, car, shed, an air conditioned space in the tropics) to a warm humid place (house, outside tropics), condensation may coat circuit boards and other insulators, leading to short circuit inside the equipment. Such short circuits may cause substantial permanent damage if the equipment is powered on before the condensation has evaporated. A similar condensation effect can often be observed when a person wearing glasses comes in from the cold (i.e. the glasses become foggy).[27] It is advisable to allow electronic equipment to acclimatise for several hours, after being brought in from the cold, before powering on. Some electronic devices can detect such a change and indicate, when plugged in and usually with a small droplet symbol, that they cannot be used until the risk from condensation has passed. In situations where time is critical, increasing air flow through the device's internals, such as removing the side panel from a PC case and directing a fan to blow into the case, will reduce significantly the time needed to acclimatise to the new environment.
In contrast, a very low humidity level favors the build-up of static electricity, which may result in spontaneous shutdown of computers when discharges occur. Apart from spurious erratic function, electrostatic discharges can cause dielectric breakdown in solid state devices, resulting in irreversible damage. Data centers often monitor relative humidity levels for these reasons.

Building construction

Common construction methods often produce building enclosures with a poor thermal boundary, requiring an insulation and air barrier system designed to retain indoor environmental conditions while resisting external environmental conditions.[28] The energy-efficient, heavily sealed architecture introduced in the 20th century also sealed off the movement of moisture, and this has resulted in a secondary problem of condensation forming in and around walls, which encourages the development of mold and mildew. Additionally, buildings with foundations not properly sealed will allow water to flow through the walls due to capillary action of pores found in masonry products. Solutions for energy-efficient buildings that avoid condensation are a current topic of architecture.

Industry

High humidity can often have a negative effect on the capacity of chemical plants and refineries that use furnaces as part of the process (e.g. steam reforming, wet sulfuric acid process). The humidity will reduce the oxygen concentration, and the flue gas fans have to pull more air through the system to get the same firing rate (dry air is 20.9% oxygen, at 100% relative humidity the air is 20.4% oxygen).
 
 
 
 
Is Humid Weather Bad for a Computer?
Yes, Humid Weather is bad for your Computer, with many houses here on the Gold Coast along the Coast and along man made canals this allows the issue to reach further inland.
Tips for Avoiding Moisture & Corrosion.
It is true that salt air will corrode hardware and electronics especially near the ocean/coast.
Whether you prefer a laptop or a desktop your PC/Mac is affected by its environment. While overly dry conditions can cause static electricity in your computer’s components, excessively humid conditions can cause faster corrosion and internal damage. If your environment is especially humid you should take precautions to protect your computer from damage due to moisture.
Take note of the general level of humidity and follow these simple steps to stop damage.
  1. Install a dehumidifier in your home or office. Dehumidifiers remove moisture in the air so it’s safer to use your desktop, laptop or tablet PC. When using a dehumidifier remember to empty out the reservoir regularly to ensure that the machine works efficiently. In our Office we use Hippos which may work for some, others may need to invest in domestic or commercial stand-alone models.
  2. Situate your computer in an area of the home or office with a controlled temperature. Avoid using your computer in humid areas such as in the Bathroom, Laundry or Outside by the Ocean. Condensation from the humidity can affect the internal components of your computer causing corrosion or sudden malfunction.
  3. Keep your computer stationary whenever possible. One way humidity builds up in your computer is when you experience sudden temperature changes. For instance, going from the cold winter air to a warm office could cause condensation. Transport your computer as little as possible and always use an insulated case to protect it from extreme temperatures if you must travel with it.
  4. Wipe your computer down quickly if you notice moisture on the outside of the case. Use a clean towel to remove outer moisture before it has time to seep into the computer through the keyboard or vents. For this very reason, avoid positioning your computer near windows or external doors.
    *Iron rust is red/brown, aluminium rust is white, copper corrosion is blue/green.*
We recommend for clients living along the Gold Coast that they get regular checkups, this ensures your PC is kept dust free and helps to prevent corrosion and overheating.
We can perform the clean onsite or in our workshop, we will also inspect your components for surface corrosion or salt buildup which is a big killer of video cards.
1962612_678873838839938_1189994760_n2rx76e0

 

Data logger 
 
 
A data logger (also datalogger or data recorder) is an electronic device that records data over time or in relation to location either with a built in instrument or sensor or via external instruments and sensors. Increasingly, but not entirely, they are based on a digital processor (or computer). They generally are small, battery powered, portable, and equipped with a microprocessor, internal memory for data storage, and sensors. Some data loggers interface with a personal computer, and use software to activate the data logger and view and analyze the collected data, while others have a local interface device (keypad, LCD) and can be used as a stand-alone device.
Data loggers vary between general purpose types for a range of measurement applications to very specific devices for measuring in one environment or application type only. It is common for general purpose types to be programmable; however, many remain as static machines with only a limited number or no changeable parameters. Electronic data loggers have replaced chart recorders in many applications.
One of the primary benefits of using data loggers is the ability to automatically collect data on a 24-hour basis. Upon activation, data loggers are typically deployed and left unattended to measure and record information for the duration of the monitoring period. This allows for a comprehensive, accurate picture of the environmental conditions being monitored, such as air temperature and relative humidity.
The cost of data loggers has been declining over the years as technology improves and costs are reduced. Simple single channel data loggers cost as little as $25. More complicated loggers may costs hundreds or thousands of dollars.

 
                  
 
Data logger Cube storing         Small data logger with integrated sensors measuring temperature, pressure, humidity, light and 3-axis acceleration
technical and sensor data
 
 
 

Data formats

Standardisation of protocols and data formats has been a problem but is now growing in the industry and XML, JSON, and YAML are increasingly being adopted for data exchange. The development of the Semantic Web and the Internet of Things is likely to accelerate this present trend.

Instrumentation protocols

Several protocols have been standardised including a smart protocol, SDI-12, that allows some instrumentation to be connected to a variety of data loggers. The use of this standard has not gained much acceptance outside the environmental industry. SDI-12 also supports multi drop instruments. Some datalogging companies are also now supporting the MODBUS standard. This has been used traditionally in the industrial control area, and there are many industrial instruments which support this communication standard. Another multi drop protocol which is now starting to become more widely used is based upon CAN Bus (ISO 11898). Some data loggers use a flexible scripting environment to adapt themselves to various non-standard protocols.

Data logging versus data acquisition

The terms data logging and data acquisition are often used interchangeably. However, in a historical context they are quite different. A data logger is a data acquisition system, but a data acquisition system is not necessarily a data logger.
  • Data loggers typically have slower sample rates. A maximum sample rate of 1 Hz may be considered to be very fast for a data logger, yet very slow for a typical data acquisition system.
  • Data loggers are implicitly stand-alone devices, while typical data acquisition system must remain tethered to a computer to acquire data. This stand-alone aspect of data loggers implies on-board memory that is used to store acquired data. Sometimes this memory is very large to accommodate many days, or even months, of unattended recording. This memory may be battery-backed static random access memory, flash memory or EEPROM. Earlier data loggers used magnetic tape, punched paper tape, or directly viewable records such as "strip chart recorders".
  • Given the extended recording times of data loggers, they typically feature a mechanism to record the date and time in a timestamp to ensure that each recorded data value is associated with a date and time of acquisition in order to produce a sequence of events. As such, data loggers typically employ built-in real-time clocks whose published drift can be an important consideration when choosing between data loggers.
  • Data loggers range from simple single-channel input to complex multi-channel instruments. Typically, the simpler the device the less programming flexibility. Some more sophisticated instruments allow for cross-channel computations and alarms based on predetermined conditions. The newest of data loggers can serve web pages, allowing numerous people to monitor a system remotely.
  • The unattended and remote nature of many data logger applications implies the need in some applications to operate from a DC power source, such as a battery. Solar power may be used to supplement these power sources. These constraints have generally led to ensure that the devices they market are extremely power efficient relative to computers. In many cases they are required to operate in harsh environmental conditions where computers will not function reliably.
  • Portable Dataloggers may reach up to 20 channels with maximum 10ms (100Hz) sampling rate.
    This unattended nature also dictates that data loggers must be extremely reliable. Since they may operate for long periods nonstop with little or no human supervision, and may be installed in harsh or remote locations, it is imperative that so long as they have power, they will not fail to log data for any reason. Manufacturers go to great length to ensure that the devices can be depended on in these applications. As such dataloggers are almost completely immune to the problems that might affect a general-purpose computer in the same application, such as program crashes and the instability of some operating systems.

Applications

Data logger application for weather station at P2I LIPI
Applications of data logging include:
  • Unattended weather station recording (such as wind speed / direction, temperature, relative humidity, solar radiation).
  • Unattended hydrographic recording (such as water level, water depth, water flow, water pH, water conductivity).
  • Unattended soil moisture level recording.
  • Unattended gas pressure recording.
  • Offshore buoys for recording a variety of environmental conditions.
  • Road traffic counting.
  • Measure temperatures (humidity, etc.) of perishables during shipments: Cold chain.[1]
  • Measure variations in light intensity.
  • Process monitoring for maintenance and troubleshooting applications.
  • Process monitoring to verify warranty conditions
  • Wildlife research with pop-up archival tags
  • Measure vibration and handling shock (drop height) environment of distribution packaging.[2]
  • Tank level monitoring.
  • Deformation monitoring of any object with geodetic or geotechnical sensors controlled by an automatic deformation monitoring system.
  • Environmental monitoring.
  • Vehicle Testing (including crash testing)
  • Motor Racing
  • Monitoring of relay status in railway signalling.
  • For science education enabling 'measurement', 'scientific investigation' and an appreciation of 'change'
  • Record trend data at regular intervals in veterinary vital signs monitoring.
  • Load profile recording for energy consumption management.
  • Temperature, humidity and power use for heating and air conditioning efficiency studies.
  • Water level monitoring for groundwater studies.
  • Digital electronic bus sniffer for debug and validation

Examples

  • Black-box (stimulus/response) loggers:
    • A flight data recorder (FDR), a piece of recording equipment used to collect specific aircraft performance data. The term may also be used, albeit less accurately, to describe the cockpit voice recorder (CVR), another type of data recording device found on board aircraft.
    • An event data recorder (EDR), a device installed by the manufacturer in some automobiles which collects and stores various data during the time-frame immediately before and after a crash.
    • A voyage data recorder (VDR), a data recording system designed to collect data from various sensors on board a ship.
    • A train event recorder, a device that records data about the operation of train controls and performance in response to those controls and other train control systems.
    • In automobiles, all diagnostic trouble codes (DTCs) are logged in engine control units (ECUs) so that at the time of service of a vehicle, a service engineer will read all the DTCs using Tech-2 or similar tools connected to the on-board diagnostics port, and will come to know problems occurred in the vehicle. Sometimes a small OBD data logger is plugged into the same port to continuously record vehicle data.
    • In embedded system and digital electronics design, specialized high-speed digital data logger help overcome the limitations of more traditional instruments such as the oscilloscope and the logic analyzer. The main advantage of a data logger is its ability to record very long traces, which proves very useful when trying to correct functional bugs that happen once in while.
    • In the racing industry, Data Loggers are used to record data such as braking points, lap/sector timing, and track maps, as well as any on-board vehicle sensors.
  • Health data loggers:
    • The growing, preparation, storage and transportation of food. Data logger is generally used for data storage and these are small in size.
    • A Holter monitor is a portable device for continuously monitoring various electrical activity of the cardiovascular system for at least 24 hours.
    • Electronic health record loggers.
  • Other general data acquisition loggers:
    • An (scientific) experimental testing data acquisition tool.
    • Ultra Wideband Data Recorder, high-speed data recording up to 2 GigaSamples per second.
    • An open source data logger based on the Raspberry Pi computer

Future directions

Data Loggers are changing more rapidly now than ever before. The original model of a stand-alone data logger is changing to one of a device that collects data but also has access to wireless communications for alarming of events, automatic reporting of data and remote control. Data loggers are beginning to serve web pages for current readings, e-mail their alarms and FTP their daily results into databases or direct to the users. Very recently, there is a trend to move away from proprietary products with commercial software to open source software and hardware devices. The Raspberry Pi single-board computer is among others a popular platform hosting real-time Linux or preemptive-kernel Linux operating systems with many
  • digital interfaces like I2C, SPI or UART enabling the direct interconnection of a digital sensor and a computer,
  • and unlimited number of configurations to show measurements in real-time over the internet, process data, plot charts and diagrams...
There are more and more community-developed (open source) projects for data acquisition / data logging  

 
 
A temperature data logger, also called temperature monitor, is a portable measurement instrument that is capable of autonomously recording temperature over a defined period of time. The digital data can be retrieved, viewed and evaluated after it has been recorded. A data logger is commonly used to monitor shipments in a cold chain and to gather temperature data from diverse field conditions. 
 
 
 
 
 
A variety of constructions are available. Most have an internal thermistor or thermocouple or can be connected to external sources. Sampling and measurement are periodically taken and digitally stored. Some have a built in display of data or out-of-tolerance warnings. Data retrieval can be by cable, RFID, wireless systems, etc. They generally are small, battery powered, portable, and equipped with a microprocessor, internal memory for data storage, and sensors. Some data loggers interface with personal computers or smart phones for set-up, control, and analysis.
Some include other sensors such as relative humidity, wind, light, etc. Others may record input from GPS devices.
Depending on the use, governing quality management systems sometimes require calibration to national standards and compliance with formal verification and validation protocols
Choices of temperature data loggers can be based on many factors, such as:
  • Cost
  • Reusability
  • Battery life
  • Ease of use; set-up, readability, download data, analysis, etc.
  • Temperature range
  • Number of measurements stored
  • Accuracy and precision - degree of agreement of recorded temperature with actual
  • Resolution
  • Response time – the time required to measure 63.2% of the total difference between its initial and final temperature when subjected to a step function change in temperature; other points such as 90% are also used.[2]
  • shock and vibration resistance
  • Water resistance – humidity, condensation, etc.
  • Size, weight, mounting
  • Certifications, calibrations, etc.
  • Software
  • Data export
  • Data integration with other systems

Uses

Environmental monitoring

Autonomous data loggers can be taken to diverse locations that cannot easily support fixed temperature monitoring equipment.[3] These might include: mountains, deserts, jungles, mines, ice flows, caves, etc. Portable data loggers are also used in industry and laboratory situations where stand-alone recording is desired.

Monitor shipments

Temperature sensitive products such as foods,[4] pharmaceuticals,[5] and some chemicals are often monitored during shipment and logistics operations. Exposure to temperatures outside of an acceptable range, for a critical time period, can degrade the product or shorten shelf life. Regulations and contracts make temperature monitoring mandatory for some products.
Data loggers are often small enough to be placed inside an insulated shipping container or directly attached to a product inside a refrigerator truck or a refrigerated container. These monitor the temperature of the product being shipped. Some data loggers are placed on the outside of the package or in the truck or intermodal container to monitor the air temperature. Placement of data loggers and sensors is critical: Studies have shown that temperatures inside a truck or intermodal container are strongly affected by proximity to exterior walls and roof and to locations on the lading.
Modern digital data loggers are very portable and record the actual times and temperatures. This information can be used to model product degradation and to pinpoint the location and cause of excessive exposure.
The measured data reveals whether the goods in transit have been subjected to potentially damaging temperature extremes or an excessive Mean kinetic temperature. Based on this data, the options may be:
  • If there have not been out of tolerance temperatures for critical times, continue to use the shipment, without special inspection
  • If potentially damaging temperature hazards have occurred, thoroughly inspect the shipment for damage or degradation. Possibly accelerate sale and use because of reduced shelf life.[8]
  • The consignee may negotiate with the carrier or shipper or even choose to reject a shipment where sensors indicate severe temperature history
  • The time of the temperature extreme, or GPS tracking, may be able to determine the location of the infraction to direct appropriate corrective action.
Multiple replicate shipments of data loggers are also used to compare modes of shipment (routes, vendors) and to develop composite data to be used in package testing protocols


=================THUMBLERER DEBT COSTING ===================



Rabu, 13 September 2017

Electric and electronic Car AMNIMARJESLOW GOVERNMENT 91220017 LOR SPEED CYCLOTRON LJBUSAF




   Hasil gambar untuk electric to electric on the future
        
The electric car (EV) is a relatively new concept in the world of the automotive industry. Although some companies have based their entire model of cars around being proactive and using electricity, some also offer hybrid vehicles that work off both electricity and gas. An electric car such as Nissan Leaf, Ford Focus Electric or Tesla Model S, Chevrolet Volt is a great way for you to not only save money, but also help contribute towards a healthy and stable environment.
Cars produce a lot of carbon emissions that are ejected into our natural atmosphere, leaving us vulnerable to things like pollution and greenhouse gases. In order to help positively the environment we live in, an electric car is a great step forward. By buying an electric car, you can also receive government subsidies for being environmentally conscious. Although you may end up paying more for your vehicle, the positives greatly overshadow the negatives. However there are still two sides to consider when you’re thinking about investing in an electric vehicle. 

EV’s get their power from rechargeable batteries installed inside the car. These batteries are not only used to power the car but also used for the functioning of lights and wipers. Electric cars have more batteries than normal gasoline car. It’s the same kind of batteries that are commonly used when starting up a gasoline engine. The only difference comes in the fact that in electric vehicles, they have more of them which are used to power the engine.


File:Hybrid modes.gif 


Advantages of an Electric Car

An electric car is a great way for you, as a consumer, to save a lot of money on gas. However, there are so many different reasons why you should invest in an electric car in the modern day of technology.
1. No Gas Required: Electric cars are entirely charged by the electricity you provide, meaning you don’t need to buy any gas ever again. Driving fuel based cars can burn a hole in your pocket as prices of fuel have gone all time high. With electric cars, this cost can be avoided as an average American spends $2000 – $4000 on gas each year. Though electricity isn’t free, an electric car is far cheaper to run.
2. Savings: These cars can be fuelled for very cheap prices, and many new cars will offer great incentives for you to get money back from the government for going green. Electric cars can also be a great way to save money in your own life.
3. No Emissions: Electric cars are 100 percent eco-friendly as they run on electrically powered engines. It does not emit toxic gases or smoke in the environment as it runs on clean energy source. They are even better than hybrid cars as hybrids running on gas produce emissions. You’ll be contributing to a healthy and green climate.
4. Popularity: EV’s are growing in popularity. With popularity comes all new types of cars being put on the market that are each unique, providing you with a wealth of choices moving forward.
5. Safe to Drive: Electric cars undergo same fitness and testing procedures test as other fuel powered cars. In case an accident occurs, one can expect airbags to open up and electricity supply to cut from battery. This can prevent you and other passengers in the car from serious injuries.
6. Cost Effective: Earlier, owing an electric car would cost a bomb. But with more technological advancements, both cost and maintenance have gone down. The mass production of batteries and available tax incentives have further brought down the cost, thus, making it much more cost effective.
7. Low Maintenance: Electric cars runs on electrically powered engines and hence there is no need to lubricate the engines. Other expensive engine work is a thing of past. Therefore, the maintenance cost of these cars has come down. You don’t need to send it to service station often as you do a normal gasoline powered car.
8. Reduced Noise Pollution: Electric cars put curb on noise pollution as they are much quieter. Electric motors are capable of providing smooth drive with higher acceleration over longer distances.
Many owners of electric cars have reported positive savings of up to tens of thousands of dollars a year. Considering the demand for oil will only be going up as the supplies run out, an electric car will most likely be the normal mode of transportation in the coming future. Companies like Nissan and Tesla offer great electric models with an outstanding amount of benefits for people who decide to invest. You’ll be saving not only yourself, but also your family a huge amount of money. The environmental impact of an electric car is zero, as well – meaning you’re reducing your carbon footprint and positively affecting the economy. 



Disadvantages of an Electric Car

Although the evidence of the positives has become very clear, there are also some downsides that each individual needs to consider before they decide to make an electric car their next big investment. These reasons are:
1. Recharge Points: Electric fuelling stations are still in the development stages. Not a lot of places you go to on a daily basis will have electric fuelling stations for your vehicle, meaning that if you’re on a long trip and run out of a charge, you may be stuck where you are.
2. Electricity isn’t Free: Electric cars can also be a hassle on your energy bill if you’re not considering the options carefully. If you haven’t done your research into the electric car you want to purchase, then you may be making an unwise investment. Sometimes electric cars require a huge charge in order to function properly – which may reflect poorly on your electricity bill each month.
3. Short Driving Range and Speed: Electric cars are limited by range and speed. Most of these cars have range about 50-100 miles and need to be recharged again. You just can’t use them for long journeys as of now, although it is expected to improve in future.
4. Longer Recharge Time: While it takes couple of minutes to fuel your gasoline powered car, an electric car take about 4-6 hours to get fully charged. Therefore, you need dedicated power stations as the time taken to recharge them is quite long.
5. Silence as Disadvantage: Silence can be a bit disadvantage as people like to hear noise if they are coming from behind them. An electric car is however silent and can lead to accidents in some cases.
6. Normally 2 Seaters: Most of the electric cars available today are small and 2 seated only. They are not meant for entire family and a third person can make journey for other two passengers bit uncomfortable.
7. Battery Replacement: Depending on the type and usage of battery, batteries of almost all electric cars are required to be changed every 3-10 years.
8. Not Suitable for Cities Facing Shortage of Power: As electric cars need power to charge up, cities already facing acute power shortage are not suitable for electric cars. The consumption of more power would hamper their daily power needs.
9. Some governments do not provide money saving initiatives in order to encourage you to buy an electric car.
10. Some base models of electric cars are still very expensive because of how new they are and the technology it took to develop them.
Just because there is a variety of factors doesn’t mean they have to be overwhelming. Doing a fair bit of research into different models, and maybe even hybrids, will help you make an accurate decision moving forward. However, no matter how you look at it, an electric car can save our precious environment.


The study has identified not just electric car charging points but also "positivity" lamp posts and fingerprint-activated door locks as some of the most sought-after features for home buyers in the next two decades. "Positivity" lamp posts are supposed to beam colorful lighting during winter to combat SAD (seasonal affective disorder).

As for the electric charge points, seen as how there are already over 60,000 home chargers in the UK, we could hardly call this a trend reserved only for the future. In fact, presently, around 90% of electric car charging is done at home.

Other results indicate that most people believe electric cars will become an essential part of housing development across the UK, with nearly 72% saying they expect EVs to be the most common type of vehicle on residents' driveways. Only 26% of people think hydrogen cars will become a more familiar fixture in the future.

Furthermore, people think that technology will make them more willing to share a vehicle with their neighbors in the next 20 years, with over a tenth of people believing that it could lead to a stronger relationship between neighbors.

"Electric cars are high performing, fun, exciting and financially compelling. There are currently over 75,000 on UK roads, a growth of 37% in a year, based on sales from January to September. Their role both now and in the future is unquestionable, as indicated by the £80m invested by government in further improving the nation’s electric vehicle infrastructure," stated Poppy Welch, head of the Go Ultra Low campaign.

    


  



As electric vehicle sales take off, the charging infrastructure is keeping pace and paving the way for convenient all-electric driving. Combine that with constant improvements in our battery performance and we believe the tipping point for mass EV uptake is upon us. As with similar breakthrough technologies, the adoption of electric vehicles should follow an ‘S-curve’ of demand. A gradual uptake from early adopters accelerates to a groundswell of consumers buying electric vehicles just as they would any other powertrain", 


 
 
                                  For future electric cars, a faster way to charge
 
Electric vehicles have developed a passionate following in California, but they have largely failed to catch on nationwide. Photo: Michael Cummo, Hearst Connecticut Media 
 
As electric vehicles start to offer more miles on a fully juiced battery — enough to take a real trip rather than shuttle between home and office — the stations that recharge them will need to improve too.
So on Thursday, a Campbell company is unveiling a recharging station it estimates will be good for the next 10 years of electric-vehicle evolution.
ChargePoint plans to introduce its Express Plus high-speed charging stations, with installation scheduled for July. The stations can recharge any currently available electric car at the maximum possible speed — a speed determined by the specifics of each car and its battery pack.
 
But the stations are also designed to be future-proof.
According to the company, they can deliver more electricity in an instant — up to 400 kilowatts — than any current plug-in vehicle can handle. That means as electric cars hit the market with better battery packs, the Express Plus stations will be able to charge them at their fastest possible rate as well.
 
It will support any battery pack that’s even being considered,” said Pasquale Romano, ChargePoint’s chief executive officer.
Most publicly available charging stations, known as level 2 stations, add roughly 25 miles of driving range in an hour and aren’t suited to short pit stops. True to their name, DC fast chargers are quicker, offering up to 40 miles of range for every 10 minutes, but fewer have been deployed.
 
Electric vehicles have developed a passionate following in California, but they have largely failed to catch on nationwide. According to the Edmunds.com auto information service, they accounted for just 0.37 percent of new car sales in the United States last year.
Cheap gasoline prices have played a big part in blunting their appeal. But so have the limited battery range of most electric vehicles — less than 100 miles per charge, for most models — and the lack of public charging stations, particularly those that can operate at higher speeds.
Palo Alto’s Tesla sidestepped the problem by creating its own network of chargers and giving Tesla owners free access to them. The system has proved so popular that the company announced in November that it would stop offering unlimited free charging to future Tesla buyers. (In a tweet this week, Tesla said that prospective buyers have until Jan. 15 to lock in free charging.)
“It gives buyers a more traditional car ownership experience, where you can drive from San Francisco to L.A., and you’re not necessarily tethered to your home,” said Jeremy Acevedo, senior analyst with Edmunds. “The ability to charge your vehicle no matter where you’re at, that certainly can do a lot to get people over range anxiety.”
Romano said, however, that ChargePoint’s new stations aren’t intended to become the primary means for drivers to fill up their vehicles. Instead, the company wants to place the stations along freeways to facilitate long-distance travel. Most users, Romano said, will still do their primary charging at home or at work, using slower chargers.
“For highways and major corridors, it’s imperative to have it as fast as possible, because people are trying to go beyond their maximum battery range, and they don’t want to stop for more than a coffee,” he said. 
 
 
Hasil gambar untuk electric to electric on the future 
 
                            Are Plugless Electric Vehicles the Future of Transportation?  
 
 
Graphic of In-Ground Wireless Charging 
    
                                   Graphic of In-Ground Wireless Charging  
 
Has the time come to cut the cord?
Electric Tram in Korea
Electric Tram in Korea
Should an electric vehicle be able to travel down the road endlessly, without the need to ever plug in?
That is the ultimate goal of a research team at the Korea Advanced Institute of Science and Technology (KAIST), which developed  an “on-line electric vehicle” (OLEV) system.  This is by no means a revolutionary idea, as other firms have toyed with and tested similar systems, but KAIST seems to be ahead of the game in this arena.
By embedding transmitting coils in roadways, electric vehicles, equipped with receiving coils, could constantly charge by driving down the road.  Range becomes a non-issue and the plug disappears forever.  At least in theory.
Implementation of such a system on a grand scale is prohibitively expensive and not practical, but the system works.
Research at KAIST began in 2009 KAIST with funding of $25 million.  In March 2010, an electric tram emerged at Seoul Grand Park that was recharged by coils embedded under the concrete.
Today, the tram continues to loop the park without a cord thanks to 370 meters of buried transmitting coils.  The transmitters send 62 kilowatts of juice to receiving coils on the underside of the tram.  The tram operator need only keep the tram aligned with the coils to maintain charge.
In theory this works and since the tram employs a battery that’s 40 percent the size and weight it would need if it couldn’t charge wirelessly, the tram is significantly cheaper to manufacture.
This system and setup makes perfect sense, but tearing up roads to embed transmitting coils is not financially viable.  However, if when roads were due for replacement, transmitting coils were installed, then bit by bit an OLEV system could become reality.  But we’re doubtful it ever will. 
 

the slotless slot car 

 
 
Wireless power transmission from the road to an electric car is improving.  (via IEEE Spectrum) .. still a lot of problems (cost in particular), but there are domains where it might make sense.
Ultimately electric vehicles probably win as their efficiency, even if they use lossy wireless transmissions schemes, are are greater than vechiles that use heat engines.  A practical and inexpensive air-metal battery would have a dramatic impact, but we're some time away from that goal. 
 

WINSmartEVTM - Electric Vehicle (EV) Integration into Smart Grid with UCLA WINSmartGridTM Technology

California constitutes a significant automotive market - a place where demanding and energy-conscious consumers come together with creative designers from Hollywood, resulting in an environment rich in ideas on automotive innovation. As a result, California is home to some of the most significant innovations in EVs including Tesla and Fisker. As these innovations come on line their integration into the smart grid of the future becomes the next big challenge. We are developing a scalable and robust architecture utilizing wireless and RF-monitoring and control technologies derived from our REWINSTM research called WINSmartGridTM that allows smart vehicle and energy storage and consumption management for vehicles in home or in the office. As part of the challenging long-term research project, we are developing a series of demonstrations both at home and in the office. The first phase - developing an on-campus demonstration within UCLA - requires conducting research and demonstration on UCLA's internal electric vehicle (EV) fleet and charging stations at UCLA for its integration with our local utility's managed grid.
The objective of this project is to reduce energy cost and usage and to increase the stability of local power system by managing the charging operations of the EVs. This will be accomplished using the smart grid wireless system under development at UCLA called WINSmartGridTM.
In this project, EV usage information and electric grid status will be collected wirelessly to determine better efficient and economic charging operation of the EVs. Due to different grid stability/reliability, geographical location of the EVs and driving patterns of the EVs, effective management of charging and backfill operations may be used to lower electricity rates and flatten electric load curve. Each EV will be equipped with a handheld device to allow the driver to receive instructions or seek advice to better manage his/her EV's battery charging/backfill process.
For example, an alert can be issued to the driver when the battery capacity is below a threshold level. The alert can include a list of near-by charging station's location, distance, current and projected energy cost based on the time of the day and use an intelligent cloud-computing the driver the optimum course of action.
The batteries on the EVs when not in driving status can also be collectively used to serve as the energy storage which can backfill into the local electric grid to prevent power outage during peak demand. In this scenario, an alert is issued to the driver when a predicted instability in the grid is detected. The alert can instruct the driver to bring the vehicle to the appropriate charging station to serve as backfill battery.
Existing EVs and charging stations usage patterns will be studied to determine the appropriate sensors and wireless communication modules to be installed. Communication and alerting systems will be implemented by integrating WINSmartGridTM with our local utility's Advanced Metering Infrastructure (AMI) and the Demand Respond project.
Major areas of this research/demonstration include:
  • WinSmartGridTM Technology - WinSmartGridTM platform is used as the infrastructure to i) connect to EV electric power sensors, GPS chips, and other EV data and ii) control and utilize the wireless network for communication iii) allow data filtration, aggregation and messaging, and iv) provide a portal for data integration and decision making.
  • Smart Energizing - the management of EV batteries' charging rate and extent of the charge backfill based on various data from grid stability, energy cost, vehicle location, battery status, driver's preference, and driving patterns.
  • Grid Balancing - grid management and prediction of peak and off-peak hours to store excess capacity, or to handle demands for large numbers of EVs charging efficient, economically and safely.
  • UCLA-WINRFIDTM Technology - including RFID tags/readers on the EVs and charging stations to track and identify usage and preference information of each EV. Automatic charge/discharge intelligence stored within smart RFID tags managed by UCLA-WINRFID Technology.
  • Cyber Security - study and integration of cyber security technologies for secure wireless communication between battery and infrastructure or between two batteries, as part of the smart grid architecture.

Toyota Develops System that Enables Electric Vehicles To Power Your Home



The demonstration and results of this project will provide vast amounts of data, information and knowledge to allow an effective and large scale roll-out of grid-integrated EVs across the region and in the country. 


        
Toyota just announced that it has developed a new vehicle-to-home (V2H) power system for the mutual sharing of power between electric vehicles and homes. The two-way electric power supply system can supply power from home to vehicle as well as from vehicle to home. Toyota is going to start testing the system in ten households at the end of 2012 with the help of the Toyota Prius plug-in hybrid vehicle....




“A lot of people will be surprised by how quickly electric cars will take over,”
In a way, the final hurdle for electric vehicles is the network needed to keep them running  —  the charging stations. Running cars with limited ranges on batteries harkens to our harried lives holding dead smartphones and searching for a power outlet. But charging stations aren’t nearly as ubiquitous and a dead car halts life a wee bit more than a dead smartphone.
What makes this a more frustrating hurdle to overcome is the inherent paradox: What comes first? The demand for cars or charging stations.
There isn’t a sufficient number of charging stations available today and what’s available (mostly in the US and China) is usually concentrated in a few urban areas (unlike the widespread distribution of fuelling stations). If an electric car is your primary (or only) transportation, it limits your ability to move.
 
But this is changing rapidly. Public utilities in the US are looking to invest in charging stations across various states 
 
 
Increasing the speed of charging has other implications. Rapidly increasing the amount of power a single EV can suck will create a spike in consumption that could even bring down the entire power grid which isn’t set up to handle these surges.
The solution would be to equip charging stations using intermediate storage (battery storage) that juices up on a consistent basis while offering surge charging to the cars that plug in. In the slightly longer term, the grid itself will get redefined to include storage devices (including EVs) essentially making everything one large interconnected network that can balance the power needs.
In a way this is the biggest challenge for electric cars  —  reshaping the infrastructure around charging and power distribution so they can scale.
 
For the future of electric vehicles, one size does not fit all
 


In an effort to jumpstart adoption of fuel cell electric vehicles, Toyota Motors earlier this month made more than 5,600 patents available to other carmakers. A few days later, General Motors introduced the electric Bolt, an electric vehicle designed to run 200 miles on batteries.
Automakers, meanwhile, continue to develop yet other types of electric vehicles: plug-in hybrids and hybrid electrics.
Electric vehicles are the most promising alternative to conventional gasoline and diesel-powered cars. But how is each technology different? And what are the relative benefits and commercial challenges to each?

How we got here

Let’s start with similarities. Plug-in battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and hydrogen fuel cell electric vehicles (FCEVs) are all electric vehicles. They’re all propelled by an electric motor and have batteries to store or supply electricity as required and absorb energy when braking the vehicle.
Some of these vehicles can also generate electricity on board, either through a gasoline-powered combustion engine or a hydrogen-powered fuel cell.
They all represent a fundamental break from the gasoline combustion vehicles we drive today in three ways: the drivetrain is electric, rather than mechanical; the engine under the hood is electrochemical instead of combustion-based; and the fuel is electricity and hydrogen, rather than gasoline.
The forces behind these technological shifts began in the late 1980s with automobile manufacturers’ acknowledgment that the long-term availability of petroleum is limited and that an alternative vehicle platform and fuel would be needed to assure a viable future business model. Hydrogen was selected as the fuel and a 25-year path for fuel-cell vehicle commercialization was established.
Since 1990, three additional forces have emerged to further affirm the decision to target the hydrogen fuel cell vehicle as the product of the future, including climate change, policies that favor fuel independence, and air quality regulations, notably in California.

Battery electric vehicles (BEVs)

In the past five years, though, there’s been a resurgence of battery electric vehicles, which rely solely on battery power. Examples include the Nissan Leaf, the GM Spark and the Kia Soul. After 40 to 60 miles, the batteries are depleted and need to be recharged by plugging into a residential circuit or 220-volt, purpose-built charger at a commercial center or workplace. Charging time depends on the voltage, the charger technology and the battery “state of charge” (i.e., how much the battery has been depleted) but generally requires one to six hours to fully charge the vehicle.
A BEV is attractive because its range satisfies the majority of trips taken by the public, recharging at home is convenient, and driving is vibration-free and quiet. The size of the vehicle is relatively small, providing good maneuverability and relatively easy parking, and there are no air pollutants during driving. BEVs also have the potential to balance the electric grid by charging overnight when grid resources are under-utilized.
Working against BEVs is the time required to recharge the vehicle and the range anxiety – that is, concern over limited driving range – experienced by drivers, which effectively reduces the useful range of the vehicle. Also, charging can stress the electric grid and there are cases where there is no charging infrastructure available, particularly for people who live in apartments. 


Following California’s zero emissions vehicle mandate, BEVs were first commercialized in the 1990s but the market waned in the 2000s. With a number of passenger cars available for sale or lease, the market is being tested today to assess public demand for this limited-range, but convenient vehicle. Advances in battery technology have the potential to increase range.

Hybrid electric vehicles (HEVs)

Hybrid electric vehicles are a BEV with a gasoline combustion engine on board to generate electricity and move the car in conjunction with the electric motor. They can provide the same 300-mile range people expect with a conventional gasoline vehicle. And with advanced software controls, the combustion engine interacts with the batteries to achieve high efficiencies and low emission of pollutants.
HEVs have been offered for sale in the United States since 2000, with the Prius, first introduced by Toyota in Japan in 1997, a prominent example. In 2012 and 2013, the Prius was the best-selling vehicle in California with over seven million vehicles sold, reflecting consumers’ remarkably positive acceptance of the vehicle.

Plug-in hybrid electric vehicles (PHEVs)

PHEVs are a HEV with added battery capacity that can provide an electric drive range of between ten and 60 miles. The Chevy Volt, for example, can drive nearly 40 miles on battery power before a gasoline generator kicks in. This allows the convenience of recharging the batteries overnight at home and a daily electric range that the majority of the US public does not exceed. And the PHEV provides the 300-mile range which the driving public is accustomed to.
A plug-in Prius has a larger battery and has an all-electric range of about 10 miles before going into hybrid mode. Toyota

Hydrogen fuel cell electric vehicles (FCEVs)

Fuel cell vehicles are hybrid electric vehicles with two major differences. A fuel cell, an electrochemical device that takes a fuel, such as hydrogen, and oxygen from the air to generate electricity, replaces the gasoline engine under the hood. The fuel cell has remarkably high efficiency (three times that of the conventional gasoline automobile) and zero emission of air pollutants when driving. The product of the reaction is water, which is exhausted through the tailpipe with nitrogen and some oxygen remaining from the air. And instead of a gasoline tank, there are hydrogen storage tanks. The refueling time of a fuel cell vehicle is comparable to a conventional gasoline automobile and fuel can be sourced domestically.
Some of the challenges associated with fuel cell vehicles are the limited number of hydrogen fueling stations nationally. California has the most hydrogen fueling stations in the US, with 51 projected to be operating by the end of 2015, over 70 by the end of 2017, and 100 by 2020. Sixty eight stations are considered the initial minimum to support acceptance of fuel cell vehicles in the State.

Going forward

The market is discovering that the BEV is an attractive complement (not replacement) to the conventional gasoline vehicle. The gasoline-powered HEV and PHEV are emerging to meet environmental regulations while maintaining the overall driving experience of range and size the market is accustomed to.
The cost of the vehicles and the cost of driving the vehicles are, for all practical purposes, competitive and compelling. Depending on the cost of electricity and the cost of gasoline, the cost per mile can favor one or the other. The PHEV provides the customer with the option of using either electricity or gasoline.
The fuel cell electric vehicle is emerging as a natural evolution of the hybrid and plug-in electric hybrid. As a result, one can foresee that the BEV and the FCEV represent the next-generation alternatives to the conventional and hybridized gasoline vehicle for fulfilling light-duty transportation needs. The BEV provides convenience and maneuverability, and the FCEV provides range, flexibility in vehicle size, and rapid fueling. Both vehicles achieve fuel independence, a separation from geo-politics, and attractive environmental attributes.
The purchase cost and operating cost of battery electric and fuel cell vehicles are comparable today. It’s likely that the cost of hydrogen will decrease in the future due to market competition and advances in technology and that the cost of electricity will increase. That means the per-mile cost of operating a fuel cell electric vehicle, compared to a battery electric vehicle, will likely become lower.
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