The air borne dust deposited on the surface of photovoltaic module influence the transmittance of solar radiations from the photovoltaic modules glazing surface. This experimental work aimed to investigate the effect of dust deposited on the surface of two different types of photovoltaic modules (monocrystalline silicon and polycrystalline silicon). Two modules of each type were used and one module from each pair was left exposed to natural atmosphere for three months of winter in Taxila, Pakistan. Systematic series of measurements were conducted for the time period of three months corresponding to the different dust densities. The difference between the output parameters of clean and dirty modules provided the information of percentage loss at different dust densities. The dust density deposited on the modules surface was 0.9867 mg/cm2 at the end of the study. The results showed that dust deposition has strong impact on the performance of photovoltaic modules. The monocrystalline and polycrystalline modules showed about 20% and 16% decrease of average output power, respectively, compared to the clean modules of same type. It was found that the reduction of module efficiency (?clean ? ?dirtv) in case of monocrystalline and polycrystalline module was 3.55% and 3.01%, respectively. Moreover the loss of output power and module efficiency in monocrystalline module was more compared to the polycrystalline module.

Fibre metal laminates (FMLs) are being used to manufacture many structural components in aerospace industry because of their very high strength to weight ratios, yet the exact model for estimating fatigue crack propagation in FMLs cannot be developed because of many variable parameters affecting it. In this research, tensile strength, fatigue life and fracture toughness values of 2/1 configuration carbon reinforced aluminium laminate (CARALL), aramid reinforced aluminium laminate and glass laminate aluminium reinforced epoxy specimens have been investigated. Mechanical, chemical and electrochemical surface treatments were applied to AA 1050 face sheets to improve the adhesive properties of the laminates. The specimens were prepared using vacuum assisted resin transfer moulding technique and were cut to desired shapes. Fatigue tests were conducted on centre notched specimens according to ASTM Standard E399. Real time material data and properties of adhesive were used in definition of numerical simulation model to obtain the values of stress intensity factor at different crack lengths. It was observed that CARALL shows very superior tensile and fatigue strength because of stress distribution during failure. Numerical simulation model developed in this research accurately predicts fracture toughness of aramid reinforced aluminium laminate, CARALL and glass laminate aluminium reinforced epoxy with less than 2% error. An empirical analytical model using experimental data obtained during research was developed which accurately predicts the trend of FMLs fatigue life.

Natural fibers, especially jute fibers, have gained interest in recent decades due to their attractive mechanical properties, high cellulose percentage, low cost, biodegradability, and easy availability. In the present study, flexural and drop weight impact behavior for different weight percentages of glass and jute fiber reinforced epoxy composites are studied experimentally according to ASTM standards. The hybrid composites were prepared through the compression molding technique. Numerical simulations were performed to investigate the predictive flexural response. The leading cause of error between experimental and numerical results is the manufacturing process and the reinforcement's woven nature. On the other hand, the impact strength was studied through drop weight testing at fixed 10 J energy. It is found that damage area decreases with increasing jute percentage in glass/jute hybrid composites, showing that jute fiber contributes more towards the composites' impact strength than glass fiber. Therefore, jute fiber can replace glass fiber in the glass/jute hybrid composite as a natural and eco-friendly constituent. The microscopic study reveals that the outer glass fiber layer helps minimize the stress distribution of jute fiber. A significant drawback of compression molding is the epoxy affluent areas in the composite.

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