Photovoltaic cells are one of the renewable energy sources that have been employed to produce electrical energy from solar radiation falling on them, but not all incident radiate will produce electrical energy, part of those radiate cause the panel temperature to rise, reducing its efficiency and its operational life, unless an attempt is made to employ one of the traditional cooling methods or innovating other methods to cooling it to reduce this effect, which it represented in the active and passive cooling method. In fact, it is difficult to compare the active method with the passive method, as each method has its Advantages and disadvantages that may suit one region without another. But in general, there are basic factors through which at least a comparison between the two methods can be made. Relatively the passive method is less expensive, in addition to no need for additional parts such as pumps and controllers, there is no energy consumption because it does not require power. But it is less effective and efficient than the active method, while the active method has the ability to disperse the heat higher than the passive method. However, it necessitates the use of electricity and is frequently costlier than the passive strategy. In this review, the most common active and passive cases were reviewed, and the pros and cons of each case are summarized in discussion due to the difficulty to list them. The review recommends that future studies should focus on active water cooling and heat-sink, both of which are viable cooling strategies.
This research focuses on studying the speed flow density relationships which are considered the fundamental traffic flow relationships. The objective of the present study is to predict statistical models represent these relationships depending on a field survey data collected from Al-Thirthar road in Falluja city.Data were collected by using video-recording technique. The required data were abstracted, analyzed, grouped, and processed using computer programs developed for this purpose. Standard statistical analysis techniques were used to examine and analyze the observed data.FWASIM simulation traffic software program was used to verify the predicted traffic stream models, while the obtained results were presented in this research. To test the validity and reliability of the model, the output results of the predicated model were compared with the output data obtained from FWASIM model using similar input data and segment geometry. The comparison leads to consider that the developed regression model may be used to evaluate the performance of urban streets in Falluja city.