Clean energy is extremely important not only because of economic purposes but also for health considerations. The use of photovoltaic (PV) systems is growing, with the increased needs for electricity. This requires more attention to research of PV systems. In this study, a method to predict the expected lifetime based on the reliability of system performance is proposed. Geographical data were collected near two different locations: Cairo, Egypt and Riyadh, Saudi Arabia. The PV system was simulated with inputs from collected data to obtain the device factors and system responses. To study the significance of inputs and device parameters on the system responses, the Taguchi OA method was used. The probability density function (pdf) of the time of acceptable performance was estimated from the simulation data. A reliability analysis method was applied to the obtained pdf to estimate the reliability function, lifetime or mean life, reliable life, and rate of failure of the used PV system as assessment factors. The results showed that the system efficiency is highly dependent on the ambient temperature, while the performance ratio depends on many variables. The reliability analysis revealed that the field orientation of 30° tilt and 20° azimuth and of 30° tilt and 30° azimuth are best for near Cairo and near Riyadh, respectively. These orientations lead to the longest mean life of 772.25 and 688.36 months for Cairo and Riyadh, respectively. It also resulted in the lowest failure rates of 0.001295 and 0.001228 per month for both regions.

Electrical energy consumption in air conditioning systems (ACS) is a sizeable portion of global electrical energy consumption. This means that it has a considerable share of global warming, which needs to be reduced. This article reviews the causes of excessive ACS energy consumption as well as modern trends in management and control of ACS energy consumption. Energy demand and consumption are high for air conditioning, especially in humid and hot weather. Opportunities for saving energy in cooling and heating systems depend mainly on reducing loads. Reducing the thermal loads can be achieved through new techniques Brief informational review of some of the most used ACS specifies cooling and heating loads and new techniques to reduce its energy consumption. Performance of ACSs for various types is mostly identified as the ratio of the active or beneficial output to the requisite total input of the equipment. The target to decrease the energy consumption of electrical systems is an essential step to define the components and equipment that are used to build the system and select the types that are considered as an energy saver. After ending this essential step we can concentrate on selecting and improving the overall system performance. Hence, this article provides review information of the most ACSs and specify its new techniques of energy consumption reduction.

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The main idea to correct sight disorders using lasers is to modify corneal curvature by applying laser to specific layers of the cornea. Intrastromal photorefractive keratectomy (ISPRK) is a laser technique used to correct sight disorders by evaporating corneal tissue from the stroma. Evaporating such tissue produces small cavities that may coincide to form a larger cavity. The composed big cavity is assumed to collapse to deform the overall curvature of the cornea. In this work, we provide finite element models to simulate the ISRPK procedure using a three-dimensional (3D) model of the cornea with typical parameters. The model outcome was compared with an earlier 2D model used for the same purpose, so as to determine its accuracy. In addition, a 3D finite element simulation of the procedure was made for a virtual astigmatic case to visualize the corneal curvature change. The results of this work show that this finite element models provide an accurate simulation of the corneal deformation expected after performing the procedure.

Due unexpected nature of renewable energy systems, the (Wind/Diesel/Battery) (W/D/B) off-grid system has initially been investigated at a South Sinai location in Egypt for home-scale consumption. Eight different systems, each of which consists of a small wind turbine, storage batteries, and diesel generator, are investigated in accordance with the varying needs of the power loads and seasonal weather data. The major goal is to investigate how adding wind power as an energy source will affect the price of electricity generated while taking into account the cost of reducing CO2 emissions as an external benefit of the wind turbine, which emits no pollutants during operation. In order to compare a Taguchi OA design to a two-level full factorial design to evaluate the systems at two separate sites (South Sinai and the Western Desert in Egypt), a design evaluation tool in DOE++ will be used. To pinpoint the crucial variables and analyze the impact of six different factors on eight different sets, Taguchi OA is used. The proportion of power shortfall is a production indicator, while the net present cost (NPC) and cost of energy (COE) are used as economic indicators. The simulation results demonstrate that W/D/B systems are economically viable for the hypothetical community site when using HOMER software, with electricity generated at a cost of about 0.285$/kWh without accounting for external benefits and 0.221$/kWh if CO2 emissions are competitive with diesel-only systems, where COE is 0.432$/kWh. As a new evaluation approach, the Box-Cox transformation calculated the best λ is about −2 at the two locations, indicating similar technique behaviors, and the fitted probability shows, meaning that the significant impact of system components are wind turbines. Regression model of CO2 emission is demonstrated to be successful for estimates at the Western Desert location than the South Sinai region