Theoretical and Experimental Study for Hybrid Journal Bearing PDFLijesh K.P., Harish Hirani, Samanta P.Journal bearings are well known for their lowest wear rate and high damping coefficients under fully developed hydrodynamic lubrication mechanism. However, metal-metal contact at start/stop and low speed condition, causing bearing wear and excessive power loss, are major disadvantages of hydrodynamic bearing. Therefore, a concept of hybrid (hydrodynamic-permanent magnetic) bearing for the radial applied load has been developed. In such bearings the static load is taken by magnetic bearing and dynamic load by hydrodynamic bearing. However, due to the unstable nature of passive magnetic bearings and larger axial thrust compared to radial thrust emphasis for the requirement of extra subassembly and proper alignment compared to conventional bearings test setup. In the present work, using 3D Coulombian model, the radial and axial forces of a passive magnetic bearing for the given dimension having different arc length of the top stator magnet have been analyzed. To reduce the unstable force, the required axial offset was estimated. After obtaining the required configuration from the theoretical results, the hybrid bearing was developed. Experiments were performed on the preliminary developed experimental setup and the challenges faced for development of setup and problems faced after performing the experiment have been reported. A detailed investigation was carried out to overcome the problems and various solutions have been provided.
mplab c18 full crack kid
Air Stirring System for Adsorption of Hexavalent Chromium onto Chitosan PDFMamdouh M.Nassar, Abd EL Hakim Daifullah, Joseph Y. Farah and H.KelanyThe adsorption of hexavalent chromium from aqueous solutions onto chitosan was investigated. The chitosan was characterized by Fourier transform infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The physical properties of chitosan were also investigated. The effect of chitosan mass, initial chromium concentrations and air flow rate on the removal of chromium in batch reactor using air stirring technique have been studied The experimental kinetic data were tested using Pseudo-first order, Pseudo-second order, Elovich and Modified Freundlich models. Three error functions were used to identify the best fit model with the experimental data. The error analysis showed that, compared with other models, the , Pseudo-second order model resulted in the lowest values for the error function and thus fitted the data better than the other models.
Power quality and stability improvement of HVDC transmission System using UPFC for Different uncertainty conditions PDFKoganti Sri Lakshmi , G.Savanthi , L. Ramadevi , Koganti Harish chowdaryThe requirement of delivering economic quality power supply has become a major concern in this developing technology therefore this desired power control at every point of power system is obtained by power controllers like HVDC and FACT devices. Considering the benefits of HVDC like cost, Technical Performance and reliability with full control over the power transmission it is used for long bulk power transmission and asynchronous interconnection. FACTS are power electronic based equipment used to control the power transfer in AC Networks. UPFC is FACT device which can provide power quality and also used for control of active and reactive power flow in transmission line. The main objective of this paper is to improve power transmission capacity and power quality of hvdc transmission using UPFC .The Conventional control scheme cannot control power fluctuations. Here we dealt different types of faults at different locations placing UPFC permanent at receiving end of the line so that the magnitude of fault current and variations of excitation voltage reduced and finally voltage magnitude is improved by UPFC. At the end, Fast Fourier Transformation analysis is carried out to determine total Harmonic Distortion with and without UPFC for different faults.
A Survey on Benchmark Defects Encountered in the Oil Pipe Industries PDFWissam Alobaidi, Eric Sandgren, Hussain Al-RizzoOil and natural gas have been transported by pipeline for over a century, yielding a large amount of information about defects in manufacture and in service. Research has moved toward early detection of defects in the body and welds of pipe during the manufacturing process. The most common defects occur in the welds, and can be categorized into 7 basic types: porosities, slag inclusions, lack of fusion, lack of penetration, cracks, burn-through and irregular shapes. Any of these may occur in the five most common welding configurations used in manufacturing. The five common joint types are: butt-weld joint, tee-weld joint, corner-weld joint, lap-weld joint and edge-weld joint. The purpose is to aid in the elimination of problems in the manufacturing process that lead to manufacturing defects, thus enhancing product quality. The relationship between defect type and the Non-destructive testing (NDT) methods which best detect each type, are summarized in tabular form. The table also relates the location of the defect (whether surface or subsurface, or both) to the NDT techniques. Illustrations of each type of defect are presented for reference. The relationship of defect type and location to cost and labor needed to detect each type, is presented in graphic form. The surface defects are easily detected with Visual Inspection, while subsurface defects can be caught with Radiographic Testing when conducted at the recommended speed of 50mm/s, but if they are missed they can be detected with Ultrasonic Testing, which is more labor-intensive, and which must be verified with a second NDT technique, Digital X-ray Testing. To enhance production efficiency, and the series of NDT stations needed for oil and natural gas pipeline manufacturing, we must determine how to incorporate new techniques to cover the shortcomings of present methods of detecting defects. This will reduce labor time and increase throughput while maintaining the quality of the finished product.
Use of Coconut Husk Fiber for Improved Compressive and Flexural Strength of Con-crete PDFAnthony Nkem Ede and Joshua Olaoluwa AgbedeRapid crack propagation, brittle mode of failure and increased overload are common in concrete structures due to the low tensile strength of concrete. Although conventional steel reinforced concrete is the most popular method developed to reduce such problems, it is rather becoming expensive in terms of its costs and sustainability issues. Because of the huge capital investment to run the steel industry, many manufacturers in the developing nations try to cut corners by reducing the quality of steel thereby reducing the strength. This has led to a lot of challenges including building collapse accompanied by devastating economic and human loss. For these drawbacks, the development of contemporary concrete technologies such as eco-friendly and affordable coconut fiber reinforced concrete needs more investigation. This research studies the effect of coconut fibers on the strength of concrete which includes the compressive and the flexural strength of normal concrete. The fibers were used in different percentages (0%, 0.25%, 0.5%, 0.75%, and 1.0%) of the weight of the fine aggregates. 16 short beams were used for flexural strength at 0%, 0.5% and 1.0% fiber content which were tested after curing for 7 and 28 days. Destructive and nondestructive compressive tests were conducted on 40 concrete cubes to doubly validate the test results. The correlation of the two tests results were very good. The results showed that the compressive strength of coconut fiber-reinforced concrete increased with curing age and with increasing percentage of coconut fiber up to 0.5% then gradually began to decrease from 0.75% to 1.0%. The percentage strength gained at 28 days for 0.25%, 0.5%, 0.75% and 1.0% fiber contents with respect to the control sample are 4.58%, 38.13%, 8.56% and -2.42% respectively. The results for the flexural strength of concrete showed that strength gained at 28 days for 0.25%, 0.5% and 1.0% of coconut husk fiber were 28.82%, 22.15% and 0.42% respectively.
Inverse Control for a Magnetic Levitation System Using the Neural Network PDFAbd-El meged Mohamed, Gaber Elsady, Ashraf Hemeda, Asmaa FawzyFor overcomes several shortcomings of the inverse control design to controlling nonlinear systems using the neural networks as the controller based self tuning regulator. The magnetic levitation parameters are estimated online and are used to update the weights of the RBFNN. The weight update equations are derived based on the least mean squares principle. The RBFNN virtually models the inverse of the plant and thus the output tracks the reference trajectory. The proposed algorithm is successfully verified using simulations. Then, this paper compared its result with the outcome of using proportional-plus-integral feedback (PI) self tuning regulator.
Optimization of the Operating Conditions of Turbidity Removal from Synthesized Dairy Wastewater Using Pumpkin Seed as a Coagulant PDFBlessing Mike JOE, Saidat Olanipekun GIWA, Maryam IBRAHIM, Yusuf Olabode RAJI, Abdulwahab GIWAThis work has been carried out to apply response surface methodology of the Design Expert to obtain the optimum conditions for using pumpkin seed coagulant to treat dairy wastewater using central composite design. The wastewater used for the research was synthesized by dissolving instant powdered milk in tap water. Also, the coagulant used for the treatment of the wastewater was prepared by processing the pumpkin seed obtained from Muda Lawal Market of Bauchi, Bauchi State, Nigeria. Before applying the Design Expert, jar test was first carried out to determine the optimum coagulant dose for the treatment of the synthesized wastewater as 4 mg/l. Thereafter, twenty experiments were designed and performed according to the central composite design of response surface methodology of the Design Expert. The results of the experiments, together with the factors used, were modelled, analysed, modified and optimized to obtain the optimum values for the wastewater treatment. The analyses of variance of the full quadratic model developed revealed that it was significant with a p-value less than 0.0001. However, the model was found to contain some insignificant factors, which made the model to undergo modification. The results obtained from the simulation of the modified quadratic model developed showed that it was very good and capable of predicting the behaviour of the process well because its R-Squared, Adj R-Squared and Pred R-Squared values were estimated to be 0.9281, 0.8861 and 0.6693, respectively. Also, the results obtained from the experiments carried out with the design of the response surface methodology showed that the minimum turbidity value given by response surface methodology was better than that of the jar test. Therefore, response surface methodology has been successfully applied to obtain the optimum conditions required for removing turbidity from dairy wastewater using pumpkin seed coagulant. 2ff7e9595c
コメント