Abstract Many of the concentrating solar power (CSP) systems are expected be installed in desert locations where lack of water and sand storms might be an issue. The solar reflectors are considered to be among the main effective components. The negative effects of the harsh weather conditions, including sand storms of the desert might have strong influence on the reflector properties, leading to a decrease in the thermal performance of such solar system. This thesis studies the sand storm influence on solar reflector surfaces, where two different types of Libyan sands were considered and taken from sites suitable for the installation of CSP. These sands have different shapes, sizes and chemical compositions. Sand "A" has particle sizes that vary from 0.025 to 0.355mm, while Sand "B" has particle sizes in the range of 0.124-0.479 mm. An erosion rig was designed and built at Cranfield University, UK. the tests were conducted under different simulated sand storm conditions for both sand samples. The results have shown that Sand "A" has more severe influence than Sand "B" because the smaller particles of Sand "A" help the spread out over a larger surface area of the reflector. The higher sand storm speed has more strong impact influence, while increasing the mass quantity results in less consequences. The reflectivity of the un-cleaned surface drops by 5% in case of using Sand "A" and by 7% in case of Sand "B", both at storm speed of 21m/s with specific sand mass of 18g/m3.Sand storms with the speed exceeding 6 m/s, generate sand impact on the reflector surface causing degradation to the surface, while storms with speeds less than 6 m/s, result in wakes of suspended small particles as a consequence of the transport mechanism in the atmosphere. Sealing simulation and cleaning process, using Ultrasonic Cleaner Model, show that sand "B" makes a loss of about 3% of the surface reflectivity, due to the salt-chemical composition leading to create spots and marks on the reflector surface. However, Sand "A" has recorded no chemical reaction. Sand storm history should be taken seriously, reflector surface materials should be suitable for the sites, and cleaning operations should be considered.
عصام ميلاد اندايا (2015)

Abstract The contribution of this thesis is to improve the understanding of acoustic dynamics in the audio duct with HQ (Herschel-Quincke tube) is essentially a hollow side-tube that travels along a main-duct axis and attaches to the main-duct at each of the two ends of the tube. In this project the detailed measurements of acoustic in a duct with HQ induced by a loudspeaker at various frequencies have been carried out experimentally. Two microphones have been used to measure the net acoustic power transmission in the duct downstream of HQ and compared with the net acoustic power transmission in the duct without the HQ. Two types of HQ and three different ducts have been studied. The acoustic wave signals are traveling in the duct as a plane wave these waves are generated by a signal generating system with a known sinusoidal wave (sine wave). One of the microphones is located just before the HQ-duct interface and the other microphone after the HQ in the duct. Labview software is used to analyze the signals with a sampling rate of 44100s/sam and number of samples is 20000. This study makes an exhaustive understanding of power spectrum of two acoustic channels in the duct with and without HQ. The results show that there is a great potential for HQ tube system to attenuate the noise over conical and cylindrical sections. The sound attenuation on conical section with short HQ shows about 70% and that of cylindrical section a meager 47% at higher frequency. Further more the sound attenuation of cylindrical section with long HQ is occurred at low frequencies.
رضوان نجمي الكوني الشريف (2010)

A requirement for new robotic manipulators is the ability to detect and manipulate objects in their environments. Robotic manipulators are highly nonlinear systems, and an accurate mathematical model is difficult to obtain using conventional techniques. Therefore, an efficient technique is required to deal with these types of complex and dynamic systems. Differential Evolution (DE) algorithm is a very powerful optimization technique and has become popular in many fields. Arguably, it is now one of the most predominant stochastic algorithms for real-parameter optimization. However, DE is very sensitive to its control parameters of the mutation operation (F) and crossover operation (CR) in such a way that their fine tuning greatly affect DE performance. Fuzzy Adaptive DE (FADE) algorithm is one of the well known adaptive DE variants that show superiority and reliability in solving different types of optimization
Azeddien Kinsheel, Rawaa Dawoud Al-Dabbagh, Saad Mekhilef, Mohd Sapiyan Baba, Shahaboddin Shamshirband(12-2014)