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摘要:This paper represents the prospect of mustard oil as a renewable and alternative fuel. To cope up with present load-shedding situation and to reduce the dependency on imported fuel, Bangladesh government is encour- aging the use of renewable energy sources. Since diesel engines have versatile uses including small irrigation pumping systems, and standby small electricity generators, use of diesel fuel is much higher than any other gasoline fuels. In Bangladesh mustard oil has been in use as edible oil throughout the country. Mustard is a widely growing plant in Bangladesh and every year the production of mustard seed exceeds the demand. So the endeavor was to use the surplus mustard oil as an alternative to diesel fuel. Fuel properties are determined in the fuel testing laboratory with standard procedure. An experimental set-up is then made to study the performance of a small diesel engine in the heat engine laboratory using different blends of bio-diesel converted from mustard oil. It is found that bio-diesel has slightly different properties than diesel fuel. It is also observed that with bio-diesel, the engine is capable of running without difficulty but with a deviation from its optimum performance. Initially different blends of bio-diesel (i.e. B20, B30, B50 etc,) have been used to avoid complicated modification of the engine or the fuel supply system. Finally, a comparison of engine performance for different blends of bio-diesel has been carried out to determine the optimum blend for different operating conditions....
摘要: align="justify"> style="font-family:Verdana;">In this paper, an attempt is made to determine the electric potential that would be generated in the piezoelectric vibra style="font-family:Verdana;">tion absorber using finite element piezoelectric analysis to determine optimal locations for damping of the first mode. Optimal placement of piezoelectric vibration absorber for passive vibration control application of a cantilever compos style="font-family:Verdana;">ite plate is investigated. Finite element piezoelectric modal analysis is performed. Models based on placing piezoelectric vibration absorbers at five different locations on the surface of the plate and incorporating piezoelectric properties are built. Modal analysis is used to find the electric potential developed in the piezoelectric vibration absorber. The location that yields the highest amount of electric potential would naturally be the best location for the vibration absorber. First bending mode of the cantilever composite plate is aimed for damping. Results of the analysis are verified with an ex style="font-family:Verdana;">perimental testing of the composite plate with piezoelectric vibration absorber firmly attached to the plate on the most effective location. A good agreement is found between the analytical and experimental results. Further, a resistive shunt circuit is designed for the passive damping of the first mode and attached to the vibration absorber in which the electric potential developed would be dissipated as heat to obtain passive vibration compensation. The experiment also demon style="font-family:Verdana;">strates that a damping of 6 percent is obtained in the first mode of vibration and a great amount of damping is achieved in the second and third modes as well.

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摘要: align="justify"> style="font-family:Verdana;font-size:12px;">Some meaningful advances have been made these last years to value precise and reliable way the residual stresses experimentally created by the autofrettage. The autofrettage process is used widely to introduce residual stresses into thick walled tubes; traditionally residual stresses have been measured using the Sachs method destructive or non-destructive methods. In this paper we describe the application of the X-rays diffraction; this technique permits to justify the presence of the compressive tangential residual stresses, and to value their distribution after two different autofrettage internal pressures loading. The results show that there is a large difference in the residual stresses find in the different autofrettege pressure. One can see the influence of the autofrettage's pressure quantity on residual stresses created in the thickness of the test tubes.

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摘要: align="justify"> style="font-family:Verdana;">In this work, machining test was carried out in various machining conditions using ultrasonic vibration capable CNC machine. For work material, alumina ceramic (Al style="font-family:Verdana;">2 style="font-family:Verdana;">O style="font-family:Verdana;">3 style="font-family:Verdana;">) was used while for tool material diamond electroplated grinding wheel was used. To evaluate ultrasonic vibration effect, grinding test was performed with and without ultrasonic vibration in same machining condition. In ultrasonic mode, ultrasonic vibration of 20 kHz was generated by HSK 63 ultrasonic actuator. On the other hand, grinding forces were measured by KISTLER dynamometer. And an optimal sampling rate for grinding force measurement was obtained by a signal proces style="font-family:Verdana;">sing and frequency analysis. The surface roughness of the ceramic was also measured style="font-family:Verdana;">by style="font-family:Verdana;">using stylus type sur style="font-family:Verdana;">face roughness instrument a style="font-family:Verdana;">nd atomic force microscope (AFM). Besides, the style="font-family:Verdana;">scanning electron microscope (SEM) was used for observation of surface integrality.

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摘要: align="justify"> style="font-family:Verdana;">This study presents a silicon-based pressure sensor with temperature compensation. The eight piezoresistors style="font-family:Verdana;">were de style="font-family:Verdana;">signed on the polycrystalline silicon membrane and constructed by two concentric Wheatstone-bridge circuits to per style="font-family:Verdana;">form two sets of sensors. The sensor in the central circuit measures the membrane deflection caused by the combined effects of pressure and temperature, while the outer one measures only the deflection caused by the working tempera style="font-family:Verdana;">ture. From this arrangement, it is reliable and accurate style="font-family:Verdana;">to style="font-family:Verdana;">measure the pressure by comparing the output signals from the two concentric Wheatstone-bridge circuits. The optimal positions of the eight piezoresistors style="font-family:Verdana;">were simulated by simula style="font-family:Verdana;">tion software ANSYS. The investigated pressure sensor was fabricated by the micro electro-mechanical systems (MEMS) techniques. The measuring performance and style="font-family:Verdana;">an style="font-family:Verdana;">indication of the conventional single Wheatstone-bridge pres style="font-family:Verdana;">sure sensor is easily affected under variation of style="font-family:Verdana;">different working temperature and causes a maximum absolute error up to 45.5%, while the double Wheatstone-bridge pressure sensor is able to compensate the error, and reduces it down to 1.13%. The results in this paper demonstrate an effective temperature compensation performance, and have a great per style="font-family:Verdana;">formance and stability in the pressure measuring system as well.

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摘要:The aim of this study was to develop an efficient and realistic response surface optimization technique for the design of V-belt drive for optimum power output of the drive in machinery design. Optimization mathematical model of the V-belt drive was constructed. The power output of the belt drive was modeled and optimized by the Response Surface Methodology (RSM). Analysis of variance was used to evaluate the extent of influence of each independent variables on the power output response of the belt drive. A RSM optimization process was proposed to calculate optimal power output for V-belt drive given a set of pulley diameter for the drive employed in a tilling machine. The analysis showed that optimum power output of the drive for workshop light operation machinery could be obtained at driving and driven pulley radius range of 550 - 900 mm and 250 - 500 mm. An optimum power output of 1418.76 kW was obtained at driving and driven pulley radius of 846 and 486 mm respectively for a farm tilling machine....
摘要: align="justify"> style="font-family:Verdana;">In this study, the homotopy analysis method (HAM) is used to solve the generalized Duffing equation. Both the frequencies and periodic solutions of the nonlinear Duffing equation can be explicitly and analytically formulated. Accuracy and validity of the proposed techniques are then verified by comparing the numerical results obtained based on the HAM and numerical integration method. Numerical simulations are extended for even very strong nonlinearities and very good correlations which achieved between the results. Besides, the optimal HAM approach is introduced to accelerate the convergence of solutions.

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摘要: style="text-align:justify;"> style="font-family:Verdana;">In this paper the ratcheting behavior of four pairs of stainless steel elbows is studied under conditions of steady internal pressure and dynamic conditions that induced out-of-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear kinematic hardening model has been used to evaluate ratcheting behavior of the piping elbows under mentioned loading condition. Material parameters have been obtained from several stabilized cycles of specimens that are subjected to symmetric strain cycles. The direction of maximum strain is at about 45 style="font-family:Verdana;">° style="font-family:'';"> style="font-family:'';"> style="font-family:Verdana;">between the hoop and axial directions. The results show that the direction of highest ratcheting is along the hoop direction rather than the direction of maximum style="font-family:Verdana;">principal strain. Also, the initial rate of ratcheting is large and then it decreases with the increasing cycles. Also, the FE method gives over estimated values compared with the experimental data. style="line-height:1.5;font-family:Verdana;">
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摘要:Modern high speed printing machines are able to print up to 700 m/min. At this rate, little excita-tions lead to vibrations, which may lead to loss of contact between the rollers (bouncing). This bouncing results in white stripes, being visible on the printed image. To enable the simulation of the whole printing process, including effects like bouncing, a discrete multibody model is developed. The rollers are modeled by several rigid bodies. These bodies are connected to each other by rotational springs, which allow simulation of the first bending eigenmodes of each roller. The contact area between the rollers is modeled by several nonlinear translational springs and damping elements. These elements change their stiffness and damping values depending on the distance between the rollers. If a defined distance is exceeded, the values become zero, which represents the loss of contact (bouncing). The unknown spring and damping elements of this model are parametrized with help of an experimental modal analysis. This paper presents the development of a flexible multibody model to simulate nonlinear effects in printing process....
摘要: align="justify"> style="font-family:Verdana;">The mechanical and damage properties of single fibres used in fibrous composite have gained tremendous importance in recent years. These properties are used in determination of effective properties of composites by micromechanics. These are also used in the micromechanical damage modeling. Further, these properties are used as an indicator of the excellence of product by manufacturers. In the present study the axial tensile modulus, ultimate strength and failure strain of single fibres are determined for carbon and glass fibres. ASTM D3379-75 standard is followed and a number of fibers are tested for statistical analysis. The axial tensile moduli measured are 246.7 GPa and 93.3 GPa, respectively and strength are 3031.6 MPa and 2035.9 MPa, respectively for carbon and glass fibres. Further, the respective axial tensile failure strains are 0.0137 and 0.0224. The error in the measurement of axial modulus is below 8% while for axial tensile strength is below 1%.

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摘要:The performance of laminar Taylor-Couette flow with different developed procedures is studied by the way of computational fluid dynamics (CFD) in steady state. In order to gain a group of developed procedure in CFD, a set of convergent solutions are used as the initial value of next boundary condition, and the new set of convergent solutions are regarded as developing from the previous steady state. Three groups of developed procedures are gained from the rotating speed series of inner cylinder, respectively from the gradual increase procedure (GIP), the gradual decrease procedure (GDP) and the sudden increase procedure (SIP). It is proved that the convergent solutions of fluid control equations are different when they are solved from laminar state with the same boundary condition, the same fluid property, the same mesh grid in CFD and the same business software except that the flow states have developed from the procedures of GDP, GIP and SIP. It is shown that the developed procedure could leave behind some information in the performance of the flow. In other words, the flow between concentric rotating cylinders has somewhat memory for the procedure of its history....
摘要: align="justify"> style="font-family:Verdana;">In order to prove the rationality of structural design and carrying capacity, reasonable design of lever-loading system to apply loadings to some loading-points was needed in spacecraft structural mechanics static test. Lever-loading system design affects the carrying capacity of test piece. style="font-family:Verdana;">This paper describes the application of different section loading beams style="font-family:Verdana;">. Optimizing and analysis the different models of loading beams, and verification the feasibility of combination beams.

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摘要:Lubrication media of rock bit journal bearing is non-Newtonian fluid, and because of structure limitations, lubricant supply is only from the inside track and its rheological properties are relatively complex. In general studies, the non- Newtonianism of lubrication media of rock bit journal bearing is neglected to simplify the research process. Based on the universal Reynolds equation of non-Newton media, the mathematical model of lubrication analysis was suitable for the rock bit bearing working conditions was established. Then according to the experimental results of rheological properties of RB-type lubricating grease, the equivalent viscosity of the model was established and this model can be solved by the method used in solving the Reynolds equation of Newton fluid....
摘要:The current cam and follower mechanism in four stroke internal combustion engine employs a flat follower. In this work an attempt is made to change the flat face of follower to a curved face follower, so that the required point contact can be achieved. As line contact between existing cam and follower mechanism results in high frictional losses which results in low mechanical efficiency. It is observed that the frequency of vibration in the existing and modified cam and follower mechanism remains almost same. The finite element approach is used to perform the analysis....
摘要:The research was motivated to establish a scientific basis for the required number of steel tie bands used in wrapping and fastening hot rolled coils produced in steel manufacture lines for safe delivery and storage. Strain gages were installed on the tie bands and stress was recorded during the banding and delivery procedure of rolls in the field. The stress developing in the bands due to fastening of the roll and that due to springback of the coil were clearly distinguishable from the strain gage signals. Twelve hot rolled coils having different yield strength, thickness, width, and weight were tested in the recoiling field. The results showed the average tensile stress developing in the bands due to the fastening of the roll to be 151.7 ± 53.8MPa, which corresponded to one fourth of the failure strength of the steel band in the buckle region. In addition to the stress caused by fastening, average tensile stress caused by springback of the rolled coils was estimated to be 33 MPa. It increased to 79 MPa when one of the tie bands was removed from the roll. Comparing the measured stress due to springback with the theoretical stress formula yielded a proportional constant value of 0.219, and a correlation coefficient of 0.914, which demonstrate the formula to be useful in predicting springback stress. The average safety factor of the tie band was found to be 3.26 and it decreased to 2.60 when one of the bands was removed from the roll. The safety factor of the band was found to decrease with increased coil thickness because the current factory standard on the number of bands does not significantly take into account of increase in the springback force with increased coil thickness....
摘要:Due to several climate changes caused by greenhouse gases and to increasing need for clean energy sources, more attention has been grew to renewable energy sources and wind energy is one of the most promising energy source in the future. The current paper presents an investigation of the wind power potential in Azraq south area, a remote location in the Northeast Badia of Jordan using real wind speed data. Also, other wind characteristics with the help of one method of meteorological and Weibull are assessed to evaluate of which at a height of 10 m above ground level and in open area. Long term data (1991-2001) period measured mean wind speed data measured at 10 m height was analyzed. Based on these data, the highest and the lowest wind power potential are in July and December, respectively. Also, it was indicated that the shape and scale parameters for Azraq south varied over a wide range. The monthly values of Weibull shape parameter k ranged from 1.05 to 4.2 with a mean value of 3.06. While the monthly values of the Weibull scale parameter c were in the range of m/s, with a mean value of 4.57 m/s. It was also concluded that the site studied was not suitable for electric wind application in large-scale. It was found that the wind potential of the region could be adequate for non-grid connected electrical and mechanical applications, such as wind generators, battery charging and water pumping as well as agricultural applications....
摘要:This paper includes descriptions of the stress distribution regularities in the tight joint parts, regularities of the stress state changes in the contact region along coupling length, stress concentration factors, levels of additional stresses caused by press fitting. Distributions of stress intensity, axial stress, contact pressure, tangent stress in parts and in contact zone along coupling length are considered. Calculation results obtained by three approaches: Lame relationships, FEM without considering assembly method, FEM with considering press fitting process are analyzed and compared. The adequacy of research carried out is confirmed....
摘要: align="justify"> style="font-family:Verdana;">Shape optimization of turbine blade to maximize the output power usually changes the power factor due to compensate Repower in a wind turbine. This article presents a multidisciplinary optimization technique to maximize the output power in Doubly Fed Induction Generator (DFIG) wind turbine. The most common parameters when operating the tur style="font-family:Verdana;">bine, namely, active power, reactive power and power factor, are considered as the problem constraints and the pitch angle grid side variable frequency converter of the turbine blades are optimized to maximize the output power. Nu style="font-family:Verdana;">merical simulation has been illustrated to present the performance of the proposed design approach.

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摘要: align="justify"> style="font-family:Verdana;">Ball bearings' rating life is reduced with the presence of hard particle contaminants in the lubricant. This life reduction is taken into account when calculating the modified rating life by using the contamination factor. The contamination factor is based on a general characterization of the lubrication conditions but the impact of contaminant's variables such as size, hardness and concentration level style="font-family:Verdana;">is style="font-family:Verdana;"> not determined in detail. In this work, greases contaminated with hard corundum (alumina, Al style="font-family:Verdana;">2 style="font-family:Verdana;">O style="font-family:Verdana;">3 style="font-family:Verdana;">) particles of different sizes are tested aiming style="font-family:Verdana;">at style="font-family:Verdana;"> finding a pattern in the relationship between particle sizes' and wear's progress. A laboratory rig is utilized for these tests and vibration analysis tools regarding bearings style="font-family:Verdana;">' style="font-family:Verdana;"> condition and estimated residual life are being assessed. After the tests, optical inspections using a stereoscope style="font-family:Verdana;"> verify the vibration analyses results. The experimental results show that wear is progressing faster when smaller particles are used. The crystalline structure of the corundum and the different degree of brittleness of the contaminants seem to be the reasons for this behavior, whereas severe abrasion and deformation of the raceways have been detected.

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摘要:The electric wheelchair is an effective machine for people with lower limb disability. The user controls the wheelchair by a joystick that helps the user to navigate the wheelchair along the desired path. Suppose the user on the wheelchair wants to operate the computer for his jobs or enjoyment, it is preferable for the user to be able to operate the computer without transferring from the wheelchair to a computer desk. Of course, some computer input devices are available for wheelchairs. One reasonable idea is to use the familiar joystick on the wheelchair as a computer input device. In this paper a joystick controller is proposed, which enables the user on the wheelchair to operate the computer settled on a nearby table. The proposed joystick controller can be achieved by mounting the sensor unit on the joystick without any modification of the conventional wheelchair controller. The principle of the sensing unit is to measure the inclination angle and the direction of the joystick with an acceleration and gyro sensor. Then the sensing unit sends the control data to the computer via an infrared or wireless signal. This proposal is based on a request done by the wheelchair users....
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