Hotplate Wind and Rain Sensor Essay Example for Free

Hotplate Wind and Rain Sensor Essay By keeping the two heated plates at a constant set point temperature it is possible to measure the power necessary to maintain this temperature. The change in power over time needed to maintain this state can be equated with wind removing heat from the plates. We can also evaporate water off one of the plates and measure the work done by the system in evaporation. The further energy required by this plate for water evaporation when measured will constitute a rain sensor. These plates will from now on be referred to as the rain plate or top plate and the wind plate or bottom plate. If the bottom plate is kept dry while being exposed to the wind it can effectively act as a reference plate to evaluate how much extra work is being done to the plate exposed to the rain also. The plates can be seen as a point source in terms of wind exposure since the heated area is small, being ~35mm*65mm. By measuring the work done on the bottom plate from some initial reference point an estimate of the cooling effect of the wind on the plate can be made, e. g. f it takes 10W/hr to maintain a temperature of 25 °C in a dry wind free environment of 20 °C and it takes 2W/hr to maintain a temp of 21 °C in the same environment then in this case if there is an additional 2W/hr used in the system we can say that a wind chill factor of –1 is present. By using a chart of wind chill factors and an equation to calculate the wind chill velocities we can estimate the win d speed. The current standard equation describing wind chill is: Ideally this equation can be solved with a temperature reading derived from the wind plate and compared to a chart of wind chill factors to find a velocity value. The problem with this approach for laboratory purposes is that the equations results becomes unreliable for temperatures above about 10 °C and since all experimental readings were conducted at room temperature i. e. ~23 °C it was difficult to use this method satisfactorily. For the evaporation of rain the latent heat of evaporation or enthalpy of evaporation of water DHvap is tabulated and has been measured as 100 °C40. 657 kJ/mol 80 °C41. 585 kJ/mol Assuming that at 90 ° the value is 41kJ/mol and that the molecular mass of water is 18. 01508 gram/mol then using this value we can say that: If we also take into account the temperature of the Aluminium tray and the heat it passes to the water then we should get an estimate for how long it will take the system to evaporate 1ml of water. For the Al tray the specific heat is taken as 938J/kg/ °K and the temperature drops by about 8 °C when 1ml of water is applied. Using where m = 10. 7*10-3 kg , c = 938 J/kg/ °K , dT = 8 ° giving the energy imparted to the water by the Aluminium trays QAl = 80J By dividing the DHvap of the rainwater by the energy supplied by the plates we should get an estimate of the time it will take to evaporate 1ml of water from the plates. Since the time taken for the plate to reheat to its 90 ° set point value is included in the measurements it is unnecessary to include the heat transferred by the Aluminium plates in the estimates. Thus Since 1g of water  » 1ml of water it’s a good estimate to say this is the time the system will take to evaporate 0. 416mm of rain. The conversion rate of 1ml of water = 0. 416mm rain or 2. 4ml of water = 1mm of rain is based on the dimensions of the Aluminium trays which have a capacity of 12ml and a depth of 5mm. 412s/ml turns out to be a slightly high estimate for the time the system takes to evaporate 1ml of water. This is possibly due to impurities in the Aluminium trays, which can lead to increased thermal emissivity. Also impurities in the water can lead to a lower density and lower latent heat. 3INSTRUMENTATION, HARDWARE AND SOFTWARE 3. 1Hardware The initial hardware in the lab was inadequate although it provided a good copy of what is probably used in similar commercial applications. There were 2 x 2cm2 Aluminium plates which were heated by small power resistors, model RF2222. These were switched by the IRF510 0. 5? rectifier mosfets, which were inset in series with 47K? resistors to reduce overheating. Both circuit loops were wired in parallel to a single power source, i. e. while each switch had its own individual digital logic voltage of 5v or 0v, the hotplates shared one power source. This made it difficult to establish which plates were active and to distinguish them from one another. Another problem with this initial circuit setup was the inadequate size of the hotplates themselves. They were too small to attach the thermocouple devices to and too flat to collect rain in since they were only flat Aluminium. These were replaced with 2 Aluminium trays which had an area of 275 mm2 , an inside depth of 5mm, a total volume of ~12. ml each and masses of 10. 70g for the top tray and 12. 35g for the bottom tray respectively. Figure 1 Detail of the Aluminium Trays and Hot plates Figure 2 shows a block diagram for the final circuit design. Figure 2 Block Diagram for the Hot plate Circuit The first change made was to replace the power resistors with 2 DBK 30W hotplates with 5. 5W/m2 heat output. These are aluminium plates heated with nichrome wire wrapped in a tubular pattern inside them. They are available in a wide range of operating modes, both ac and dc and with various power and temperature ratings. For this project I chose the HP03-1/08-24 model since they have a maximum power drain of 30W and operate at DC voltages between 12—24V. Testing them with a voltmeter showed them to have a variable resistance. They recorded a maximum of 100W at their peak temperatures and 10W at their minimum. The circuits were redesigned so that each loop had its own individual power source. This was done to more accurately measure the activity of each plate. With a separate current and voltage indicator for each plate it was easier to determine which plate was drawing power, how much and when. It also helped overcome problems of inadequate power supply to the plates, which could demand a current in excess of 2A when heating initially due to their low resistance at that stage. The IRF510 mosfet switches in series with a 49KW resistor were later replaced with lower resistance IRFZ34N rectifiers which had a lower resistance of 0. 04? compared to 0. 5W for the IRF510 to reduce heating which was occurring in them in the initial heating phase of the plates when the system was switched on. These were added to the circuit in series with a 3. 9KW resistor. The purpose of these resistances was to avoid overheating in the mosfets causing thermal breakdown. During this phase the power to the plates was a maximum as the plate resistance was lowest ~10?. In addition the power drain was continuous until they reached their set temperature so the amount of time they were switched off was a minimum. Once they reach the set point temperature they then began switching and so the continuous on time for each one was reduced. It was this time difference along with the temperature difference of the plates that was measured in this experiment. The temperature at the Aluminium measurement surfaces was measured by 2 type-j thermocouples, which were connected to the PC via the USB-TC data acquisition unit. Aluminium trays were attached to the hotplates using a nylon clip and screws and the thermocouple devices were attached to the same side of these trays further down to measure the temperature of the Aluminium trays as opposed to the temperature of the hotplates. Digital outputs on the USB-TC unit were in turn connected to the mosfet rectifiers, which switched the power supply to the plates on and off. In this way the temperature at the plates was to be maintained at a set point assigned in the software on the PC. A third thermocouple was used to record the ambient temperature in order to help accommodate calibration of the system. Rain and wind were simulated using a dropper and a spray atomiser for rain while an air pump and a hot air paint stripper were used to simulate wind. In one sample I used ice as a rain source although the data from this may be inconclusive due to difficulties measuring the quantity of ice used. Visual estimation was the only way to measure it and trying to find a 1cm3. It should also be mentioned that neither the dropper nor the atomiser represent very accurate measurement sources with errors I estimate of about  ±0. 5ml. A Velocicalc handheld anemometer was used to measure the wind speeds produced by the wind sources. 3. 2Software Initial work was done on existing VIs (Virtual Instruments) that came packaged with the USB-TC device. These included simple programs to configure the digital ports on the device and to take a reading from an analogue thermocouple port. These helped me understand the workings of Labview and in particular the objects that would be pertinent to my project. The VI developed for the wind and rain sensors in Labview worked on a timed loop basis. The outer loop was timed at the same frequency as the analogue thermocouple inputs to avoid duplicating readings in the data log file. Inside this a second loop was used to continuously change the value at the digital output ports. Depending on the output value of the PID controller a further PID analysis tool would output a Boolean value thus switching the plates on or off. This allowed much more frequent changes to the plates on/off states thus allowing more accurate control of the plates. In order to get accurate time reading for the on/off states of the plates I set them to default off in the outside loop, this meant that in each 0. 5 sec loop iteration the maximum amount of time a plate could be active was 0. 4 sec. This meant that while the system was slower to reach its set point temperature it was less prone to overshooting the set point. This was an improvement on the initial VI that was only capable of switching at the same frequency as the analogue ports and was prone to overshoot the set point temperature by about 1.  °C 2 °C. In contrast the system now recorded average temperatures ~ 0. 5 °C below the set point. The software recorded all data to an excel file which was named arbitrarily according to the timestamp on the machine at the sample start time, e. g. hotplate_data_200713021234. xls. These files recorded about 7200 records per hr and were about 0. 5mb in size before any data analysis. Each file contains rows of readings, which contain a timest amp in milliseconds and 3 temperature readings, top plate, bottom plate and ambient room temperature. Figure 3 shows the time taken to evaporate 1ml of ice over a 10-minute period with the data showing a minimum temperature recorded of 70. 005 °C. The unusual low recorded on the bottom plate is due to the sample being taken before the plate had reached its set point temperature and can be ignored. Figure 4 and Figure 5 show the difference between 1ml of water where the plates can maintain 90 °C in a wind free environment and 1ml of water in a windy environment where the maximum rain plate temperature reached was 83 °C with the rain evaporating at ~69 °C. In both cases it takes less then 400 sec to evaporate the water despite the difference in temperatures at which the plates are operating in each case. It took ~300 sec in the wind free environment to evaporate the water and in the second scenario approx 350 sec. This time difference may have been primarily due to the cooling effect of the wind on the heating element of the rain plate. Figure 1 shows the gap between the plates that allowed the wind to act on the back of the rain plate. In this case I did tilt the plates towards the wind source slightly at an angle of ~10 ° to the horizontal so both plates were exposed to the wind source. This will have had an inevitable effect on both plate temperatures. In a real implementation of a system like this the back of the plates would be thermally isolated with some kind of insulating material thus giving more credence to the results and what they imply in terms of weather effects. However the difference in base temperature can be seen clearly in the second part of Figure 5 where the plates operate at a difference of ~5 °C due to the wind. In this instance the measured wind difference between the plates was 1m/s and with a wind temperature of 25 °C. In this case the wind speeds measured using the Velocicalc were 0. 26m/s at the rain plate, 1. 26m/s at the bottom plate and 3. 52m/s at the ambient temperature thermocouple, which was located about 5cm left of the plates. Average82. 5859389. 4717824. 44208 Min70. 00585. 30724. 179 Max90. 24990. 46624. 67 Figure 3 Ice sample 1ml 10 minutes sample Average83. 9734689. 6681423. 80404 Min72. 47588. 76123. 696 Max90. 36990. 44823. 991 Figure 4 Dropper sample 1ml 10 minutes Average84. 644385. 5546425. 30292 min63. 73476. 00623. 51 max90. 28390. 48229. 856 Figure 5 Dropper sample 10 minutes 1ml with wind source It is also interesting to see that the minimum temperature reached in water was 72. 475 °C as compared to 70 °C for ice and 63. 734 °C for water in windy conditions. This shows that maintaining set point against wind speed will be a strong factor in the power drain of a real system. I took several groups of readings over one-hour intervals and with different quantities of water to try and establish the linearity of the evaporation rate of the system. I also wished to compare the different behavior of the plates due to different methods of applying the water. This would correlate to light drizzle and driving rain in terms of weather conditions. To do this I took half of the measurements with a dropper syringe and half with a perfume atomizer. In this case it could be seen that the surface area of the water particles have a distinct effect on the time taken to evaporate them. Although it is also possible that applying the water with the atomizer may have led to some of the samples missing the tray or evaporating before they contacted the tray, the figures do show an apparent difference in effects.

The Minimum Wage Should Not Be Increased :: Argumentative Persuasive Essays

"The minimum wage is something that F.D.R. put in place a long time ago during the Great Depression. I don't think it worked then. It didn't solve any problems then and it hasn't solved any problems in 50 years." -- John Raese The minimum wage in the United States was established under the Fair Labor Standards Act of 1938 in an effort to stabilize the economy following the Great Depression. It was designed to create a minimum standard of living by ensuring that workers could provide for the health and well being of their families. With its passage workers were legally ensured that they would receive a minimum of 25 cents for each hour worked. With each increase of the minimum pay rate ($7.75 today) there has been an increased level of debate. Such discussions have resurfaced again as the country attempts to deal with the impact of the Great Recession of 2008. Economists generally agree that minimum wage increases do not affect national employment significantly. However the size of an increase can have a dramatic impact on the employment of segments of the population, GDP, price of goods, and other measurements of productivity. From an economic perspective, mandated wages negatively impact society in the long run (all other variables being held constant); therefore we recommend that other policy measures be considered to narrow the inequality gap in our country. A review of the supply and demand curve provides the simplest explanation for our recommendation. A minimum wage is essentially a price floor for labor. If this floor is set above the current market price – as would be the case with an increase in minimum wage - the demand for workers will be reduced while the supply of workers will increase. As illustrated below the result would lead to increased unemployment. http://notatthedinnertable.weebly.com/uploads/3/4/1/1/3411210/5183225_orig.png Firms will retain more productive and higher paid workers, however lower skilled and lesser paid (those you intend to assist) will be shed. Those who lose their job will then require government benefits, such as unemployment compensation and welfare, to survive thus increasing government expenditures and debt. In the event that a firm does not fire workers the cost of the additional wages must be addressed. Typically the increased cost of doing business can be managed in two ways. The firm will transfer the increased cost to consumers by raising the selling price of its goods or

Organizational Behavior and Human Resources Essay

Organizational behavior is the study and application of knowledge about people or groups of people in an organization. It focuses on what people do and why they do it with aim of improving what they do. Since an organization is a collection of people working together in an organized social structure to achieve a common goal, application of theories and concepts of human behavior is imperative to attain the goals of organizations. Organizational behavior covers areas such as human behavior, leadership in an organization, teams, communications, employee relations etc. Clark, 2008). A study of the organization’s behavior helps the management to succeed in business opportunities. Human resource management is a strategic approach to the management of employees in an organization. It includes activities such as planning, selection, recruitment and maintaining employees. To sustain high performing employees, ensuring safe working environments and compliance to rules and regulations in an organization are some of the main objectives of human resource management. These objectives can only be attained through efficient analyses of the employees’ behaviors. Therefore, when human resource management and organization behavior blend together in an organization, they help to bring about strong and active workforce which help the organization meet its strategic goals. Effective policy development in human resources would help management to establish a strong workforce and explore untapped resources and strategies that would improve the organization performance. In order to employ effective policies, the management should make best decisions in a timely manner in a given situation. Human resource managers should be involved in making strategic decisions of the organization such as being informed on the long term plans of the strategic management. To amicably resolve personnel issues and find appropriate solutions to these issues, the management should have proper human resource policies. The policies should incorporate fresh ideas that reflect current situation in the organizations and the current business world in general. Human resources policies ensure that employees receive equal treatment in a wide range of employment issues and in legal matters incase they arise. To effectively develop human resource in any organization, it is necessary to have policies on employees’ benefits such as educational assistance, retirement benefits, health care and medical benefits etc. Another factor to consider when formulating the policies is the safety, health and security of the employees. Issues such as workplace violence, drugs, crisis management, and diseases like HIV/AIDS should be addressed in policy development. In addition it is important to consider employees relations which entail dispute resolutions and grievances, employee’s privacy, employee’s performance management, discipline and the conduct of employees in the organization. Selection, recruitment and placement of employees is a fundamental function in the human resource management. Discrimination in terms of race, religion, sex or in any form should be discouraged in the hiring and recruitment process. In order to improve employees’ skills and their efficiency, there should be a policy on employee training and development. In conclusion, effective policies should seek to motivate employees whereby they feel comfortable and satisfied hence improve their performance. The human resource should operate in a flexible environment. For instance, employees can operate in shifts where different people start and end their workday at different time. The organization should adopt technologies that would enable the employees to work outside the workplace. A study in organizational behavior shows that different people get motivated in different ways and can perform better under different circumstances. The management should therefore, customize their way of rewarding employees to their particular preferences (Marques, 2007).

Unit 10 Introduction to marketing research M1 - 1043 Words

Unit 10 Introduction to marketing research M1 Explain the context in which different marketing research methods are appropriate. Customer Behaviour In order to effectively undertake market research on customer behaviour; such as expected prices, how they react to certain methods of research and what kind of care do the customers expect after the purchase is made, it would be best to use observation along with focus groups. Surveys, if used, should be done face to face by door knocking as it is more convenient and has a high response rate. The survey should include quantitative and qualitative type’s questions in order to get a `broader view of the customers’ behaviour. Questions could include â€Å"What do you think affects your behaviour†¦show more content†¦This can be done mostly in quantitative format as the answers are mainly yes and no or multiple choice. This will help build nice graphs for easy analysis. Product Development Success To measure product development success I would use surveys online and pay a survey website to put your businesses questions on the site for a small fee. This will ask the public questions like if they, personally, saw the product as a success in their area of the world and questions asking what products might be needed to achieve international success. Experimentation methods can be used to develop a product by testing whether their product awareness increases after certain campaigns, different packaging or new products are released. This will help change the product over time into something they public prefer. Emergence of new markets To research the new markets that are appearing a survey method would be appropriate. It would have to be done on business critiques face to face or online and ask questions such as what products are likely to have appeal in the new market, where would consumers expect to buy this new product from and what type of promotional activity will be effective in these markets? 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