摘要: The aim of this research is to find out suitable material for insulator and their flashover performance to withstand the high pollution degree in different environmental conditions. The experimental investigation was carried out on various insulating material like porcelain, glass, and rubber to find out the artificial effluence to examine alternate current flashover potentials. The result shows that the polluted flashover voltage is affected by equivalent salt deposit density and non soluble deposit density, the authorities of which are autonomous of each one on another. The correction formulae of the flashover voltage of various insulators at various salt deposit density and non soluble deposit density levels have pointed out by means of the flashover voltages examination. Also the dissimilarity existing between the flashover voltages of various types of polluted insulators. From this we are able to conclude which insulating material withstands the pollution degree better amongst the above three.
摘要: In this paper, a velocity connection algorithm of arbitrary multi-axis linkage is presented with regard to the problem of velocity connection efficiency of multiple straight-line paths in the motion control system. For this algorithm, with the velocity, acceleration and displacement of the current segment and the previous segment as constraint conditions, the acceleration is not set as a constant but the intersegmental velocity variable is set independently. The initial velocity and final velocity of each segment is solved on this basis, improving the movement efficiency and simplifying the calculation. Therefore, this algorithm is particularly suitable for the high-speed movement mechanism driven by a stepper motor. As for the actual motion track of the rapid prototyping machine, a comparison was made between this algorithm and the traditional velocity connection algorithm to verify the effectiveness of this algorithm.
摘要: The main objective of this experimental work is to study the effect of Hydro Fluoric acid in ultrasonic machining of polycarbonate bullet proof UL-752 and Acrylic Heat resistant BS 476 Glass. In which, mixture of abrasive particle are also used as the input machining parameter. Three types of abrasive; Alumina, Silicon Carbide and Boron Carbide are used for machining. Experiment has been performed with 8mm of high carbon high chromium tool steel (D2), high carbon steel (HCS) and high speed tool steel (HSS) tools. The material removal rate was father enhanced by HF acid. The experimentation date represent the main effect plots for tool wear rate and material removal rate. After analysis, results reveals that Al2O3+SiC+B2C mixed slurry (1:1:1), Hydro Fluoric acid with 1% concentration and High Speed tool Steel material produce the higher material removal affect.
摘要: The end plug to cladding tube of fast reactor fuel pin is normally welded using Gas Tungsten Arc Welding (GTAW) process. The GTAW process has large heat input and wide heat-affected-zone (HAZ) than high energy density process such as laser welding. In the present study Laser Beam Welding (LBW) is being considered as an alternative welding process to join end plug to clad tube. The characteristics of autogenous processes such as GTAW and pulsed Nd-YAG laser welding on fuel cladding tube to end plug joints have been investigated in this study. Dissimilar combinations of modified stainless steel (SS) alloy D9 cladding tube to SS316L end plug, and similar combinations of SS316L cladding tube to SS316L end plug were successfully welded using the above two welding processes. The laser welding was performed at the butting surfaces of the cladding tube and the end plug, and also by shifting the laser beam by 0.2 mm towards the end plug side to compensate the heat balance and for improving the Creq/Nieq ratio in the molten pool. Helium Leak Test (HLT) and Radiography Test (RT) were carried out to validate the quality of the welds. The microstructures of the weld joints were analysed using optical microscope. In the present study, it has been demonstrated that it is possible to obtain welds free from hot cracks by shifting the laser beam by 0.2 mm towards end plug side, while the weld produced using the beam positioned at the interface shows cracks in the weld.
摘要: This study investigates the effect of oxidation aging on the physical properties of asphalt binder modified by various ratios of soft clay contents. The rheological properties of soft clay modified asphalt binders were performance under unaged and short-term aged, and being applied by using rotational viscometer and dynamic shear rheometer. Therefore, the results indicated that the physical properties of penetration and softening point were consistently reduced and increased, respectively for unaged and short-term aged specimens. The penetration index and viscosity aging index were increased as the soft clay modified binders aged and showed a high significance correlation. It also has the lowest susceptibility for the temperature susceptibility.
摘要: Fatigue, creep and erosion are among the factors which destroy the asphalt mixture and modifying the asphalt binder via additives such as crumb rubber, sulfur, carbon, as well as natural and synthetic polymers has been done in order to improve the strength of asphalt mixture. Knowledge in the field of nanotechnology along with its capability and attractiveness for application as nanoparticles in different industries such as asphalt industry has attracted great attention in recent years. In this study, specific percentages of TiO2 nanoparticles, namely 2, 4, and 6, were added to the asphalt binder as the nanocomponent. Done physical common tests such as penetration degree, softening point, flash point and viscosity of the base asphalt binder and modified asphalt binder, the bending beam samples composed of origin asphalt sample and modified asphalt sample with 4% TiO2 nanoparticle were subjected in different micro strains to fatigue loads. Results of four point bending fatigue test showed that the addition of TiO2 nanoparticles to the asphalt binder increased the fatigue strength in the asphalt samples. Modified asphalt binder is stiffer, more viscous than original asphalt binder and due to TiO2 nanoparticles more temperature tolerance and load bearing capacity, modified Asphalt is more resistant under fatigue loads.
摘要: The main objective of this work is to study the thermal exchanges in a habitable enclosure located in a desert region of Algeria (Adrar). This latter is considered as an air volume of parallelepiped shape limited by horizontal and vertical flat walls. The walls are the only capacitive elements of the enclosure. They are thermally coupled by convection and radiation and are the seat of conductive flux. The external facades of the enclosure are the seat of a convective flux with the external air and radiative exchanges with the environment (ground and sky). Openings (cracks, sealing defects, infiltration orifices, renewal orifices, etc.) allow the air to circulate inside the habitable enclosure and between the inside and the outside. Thermal exchanges are studied using the balance equations established at each wall of the enclosure. These equations have been discretized by an implicit finite difference method. The systems of algebraic equations thus obtained have been solved by the Gauss algorithm using the nodal method. The effects of the outdoor ambient temperature, the density of the incident solar flux on the facades and the orientation of the habitable enclosure in the meridian plane on the temperature distributions of the internal walls and the filled air in the enclosure havec been analyzed on the basis of recent climate data measured at the ADRAR Saharan Renewable Energy Research Unit. An analysis of the evolution of the internal ambient temperature as a function of the wind exposure factor of the heated space and of the degree of leaktightness of the doors and windows was also carried out at the end of this work. An acceptable agreement was found between the numerical results and those measured by the radiometric station. Moreover, the results obtained show that the building material used in this region causes undesirable overheating due to its thermal inertia.
摘要: Recently, the application of Vertical Farming into cities has increased. Vertical farming is a cultivating vegetable vertically by new agricultural methods, which combines the design of building and farms all together in a high-rise building inside the cities. This technology needs to be manifest both in the agricultural technique and architectural technology together, however, little has been published on the technology of Vertical Farming. In this study, technology as one of the important factor of Vertical farming is discussed and reviewed by qualitative approach. In the first, identifying existing and future VF projects in Europe, Asia, and America from 2009 to 2016. Then a comprehensive literature reviewed on technologies and techniques that are used in VF projects. The study resources were formed from 62 different source from 2007 to 2016. The technologies offered can be a guide for implementation development and planning for innovative and farming industries of Vertical Farming in cities. In fact, it can act as a basis for evaluating prospective agriculture and architecture together. The integration of food production into the urban areas have been seen as a connection to the city and its residents. It simultaneously helps to reduce poverty, adds to food safety, and increases contextual sustainability and human well-being.