Dynamic simulation provides an efficient approach for improving the efficiency of parabolic trough power plants and control circuits. In the dynamic simulation, the possibilities and operating conditions of the plant are evaluated regarding materials, processes, emissions, or economics. Several studies related to the dynamic simulation of the parabolic trough technology are summarised and discussed in this work. This study is the first research that presents a thorough description of the advanced control circuits used in the solar field and thermal storage system of a parabolic trough power plant. This power plant was implemented using advanced process simulation software (APROS). The dynamic model was built based on the real specifications of the power plant.
Thin-walled members are increasingly used in structural applications, especially in light structures like in constructions and aircraft structures because of their high strength-to-weight ratio. Perforations are often made on these structures for reducing weight and to facilitate the services and maintenance works like in aircraft wing ribs. This type of structures suffers from buckling phenomena due to its dimensions, and this suffering increases with the presence of holes in it. This study investigated experimentally and numerically the buckling behavior of aluminum alloy 6061-O thin-walled lipped channel beam with specific holes subjected to compression load. A nonlinear finite elements analysis was used to obtain the buckling loads of the beams. Experimental tests were done to validate the finite element results. Three factors namely; shape of holes, opening ratio D/Do and the spacing ratio S/Do were chosen to study their effects on the buckling strength of the channel beams. Finite elements results were obtained by using Taguchi method to identify the best combination of the three parameters for optimum critical buckling load, whereas determining the contribution of each parameter on buckling strength was implemented by using the analysis of variance technique (ANOVA) method. Results showed that the combination of parameters that gives the best buckling strength is the hexagonal hole shape, D/Do=1.7 and S/Do= 1.3 and the opening ratio (or size of holes) is the most effective on buckling behavior.
The objective of the research presented in this paper is to investigate the buckling behavior of a perforated thin-walled lipped channel beam subjected to combined load. A nonlinear finite element method was used to analyze the buckling behavior of the beam. Experimental tests were made to validate the finite element simulation. Three factors with three levels for each factor were chosen to examine their influence on the buckling behavior of the beam and these factors are: the shape of holes, opening ratio and the spacing ratio of. The finite elements outcome was analyzed by using Taguchi method to identify the best set of three-parameter combinations for optimum critical buckling load. The analysis of variance technique (ANOVA) was implemented to determine the contribution of each parameter on buckling strength. Results showed that the mode of buckling failure of the perforated beam is lateral-torsional buckling and the hexagonal hole shape, =1.7 and = 1.3 were the best combination of parameters that gives the best buckling strength. The results also showed that the shape of holes is the most influential on buckling behavior of the perforated beam for this case of loading.
The inverse kinematic equation for a robot is very important to the control robot’s motion and position. The solving of this equation is complex for the rigid robot due to the dependency of this equation on the joint configuration and structure of robot link. In light robot arms, where the flexibility exists, the solving of this problem is more complicated than the rigid link robot because the deformation variables (elongation and bending) are present in the forward kinematic equation. The finding of an inverse kinematic equation needs to obtain the relation between the joint angles and both of the end-effector position and deformations variables. In this work, a neural network has been proposed to solve the problem of inverse kinematic equation. To feed the neural network, experimental data were taken from an elastic robot arm for training the network, these data presented by joint angles, deformation variables and end-effector positions. The results of network training showed a good fit between the output results of the neural network and the targets data. In addition, this method for finding the inverse of kinematic equation proved its effectiveness and validation when applying the results of neural network practically in the robot’s operating software for controlling the real light robot’s position.
A fundamental task in the dynamic simulation of parabolic trough power plants (PTPP) is to understand the behavior of the system physics and control loops in the presence of weather variations. This study provides a detailed description of the advanced controllers used in the power block (PB) of a 50 MWel parabolic trough power plant (PTPP). The PB model is achieved using APROS software based on the actual specifications of the existing power plant. To verify the behaviour of the PB model, a comparison between the simulated results and given real data is documented depending on a previous study, and the results indicate a reasonable degree of correspondence. The purpose of this study is to create reference models for the PB. Thereby, developers and engineers will have a better understanding of the state of the art of advanced control loops in these power plants. Moreover, these types of models can be used to specify the most suitable mode of operation for the power plant. In addition, this study gives an overview of dynamic simulation for the design, optimisation and development of power blocks in parabolic trough power plants.
Circular thin walled structures have wide range of applications. This type of structure is generally exposed to different types of loads, but one of the most important types is a buckling. In this work, the phenomena of buckling was studied by using finite element analysis. The circular thin walled structure in this study is constructed from; cylindrical thin shell strengthen by longitudinal stringers, subjected to pure bending in one plane. In addition, Taguchi method was used to identify the optimum combination set of parameters for enhancement of the critical buckling load value, as well as to investigate the most effective parameter. The parameters that have been analyzed were; cylinder shell thickness, shape of stiffeners section and the number of stiffeners. Furthermore, to verify the contribution of parameters on buckling response, the analysis of variance technique (ANOVA) method was implemented, which gave the contribution weight as percentages. The analysis of results by these two methods showed that the more effective parameter on the critical buckling load was the thickness of cylinder’s shell and the lowest effective was the number of stiffeners The values of parameters that gave the best critical buckling load combination were: 1) the ratio of cylinder’s diameter to thickness of its shell was 133, 2) the ratio of the depth to thickness of stiffeners was1.6, and 3) the number of stiffeners was 12.
Acinetobacter spp. have risen as important pathogens in medicinal services related contaminations. Carbapenems are vital antimicrobial agents for treating diseases due to multidrug resistant Acinetobacter spp. Resistance to these drugs in the genus, may beconferred by different mechanisms particularly production of class D carbapenemases. OXA-23-like family has been brought up as one of the dominating carbapenemases among Acinetobacter. The present study aimed to investigate the occurrence of OXA-23-like carbapenemases among Acinetobacterisolatesrecovered from patients of hospitals in Babylon, Iraq. Antimicrobial susceptibility profiles were determined by disk-diffusion method.Imipenem resistant isolates were submitted to Modified Hodge Test and Double Disk Synergy Test to screen for carbapenemase generation, and later to polymerase chain reaction (PCR) to explore the presence of blaOXA-23 genes. One (10%) of isolates was observed to be imipenem and meropenem resistant (MIC > 512 μg/ml). 6(60%) gave positive results with the imipenem-EDTA disk and Modified Hodge test ; 4 isolates (40%) as indicated by PCR results, carried the blaOXA-23 genes. OXA-23-like enzymes might be a critical component of carbapenem resistance among isolates present in the hospitals studied.
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