Applied Mechanics and Materials Vols. 541-542

Abstract: In this paper heat losses from cavity receiver of solar concentrators are presented. Convective and radiative losses for specified cavity receiver are estimated by MATLAB programming and effect of the various parameters is studied. Radiation losses are analyzed for operating temperature in range of 127°C to 527 °C and aspect ratio of 0.5 to 2.5. Convective losses are investigated for operating temperature in range of 127°C to 527 °C, inclination angle from 0 to 90^o, aspect ratio of 0.5 to 2.5 and wind effect for 0 to 10 m/s. Radiation losses and convective losses increases as operating temperature of cavity receiver increases. The convective losses are more for sidewise facing cavity (0^o inclination) and less for downward facing cavity (90^o inclination). As aspect ratio and wind velocity increases, convective loss increases.

Abstract: The study is combined of initial analysis and advanced analysis via GIS to promote the research about land suitability for wind farm in the South Wales in UK. Detailed processes are provided. Weighting and possible pitfalls are discussed. This progressive study can promote the result more accuracy compared to traditional study of land suitability for wind farm.

Abstract: In this study, performance of the DRG-based chemical kinetic mechanism reduction techniques was evaluated using a diesel fuel surrogate model, which is the n-hexadecane mechanism. Following that, a new mechanism reduction scheme was developed to generate a reduced mechanism which is suitable to be applied in diesel engine applications.As a result, areduced mechanism with 49 species and 97 elementary reactions was successfully derived from the detailed mechanismwithan overall 97% reduction in species number and computational runtime in zero-dimensional closed homogeneous batch reactor simulations. After that, the reduced n-hexadecane mechanism was applied to simulate spray combustion in a constant volume bomb using OpenFOAM software. Results show that n-hexadecane alone is inappropriate to be employed as a single-component diesel surrogate as its high cetane number has resulted in advanced ignition timing. This agrees with recent study andthus fuel blending is suggested in order to match the diesel fuel kinetics and compositions.

Abstract: In this paper, analysis of total heat losses has done by constructing an experimental set up of electrically heated spherical cavity receiver of solar concentrator. Hollow spherical cavity receiver of copper material having diameter 385mm and thickness 1.5mm is used in the experimental set up. The numerical analysis has done by using the MATLAB programming. The effect of different opening ratio (0.2, 0.3, 0.4, and 0.5), different cavity inclination angles (0⁰, 25⁰, 50⁰, 75⁰, and 90⁰) and different operating temperatures (100°C to 600°C) are studied for total heat losses for spherical cavity receiver. The maximum convective losses are found at 0 degree inclination angle of cavity while the minimum convective losses are found at 90 degree inclination angle of cavity because of decrease in convective zone of air and increase in stagnation zone of air in to the cavity. Conduction and radiation losses are independent of cavity inclination angles. The convective losses are also found to be decrease with decrease in opening ratio from 0.5 to 0.2 for different cavity surface temperatures. Experimental results of spherical cavity receiver are compared with numerical results and good agreement is found between the experimental results and numerical results.

Abstract: This research aims were to evaluate drying kinetics model for describing evolution of moisture transfer of air dried sheet (ADS) rubber by using solar and biomass drying, multi-stages solar and biomass drying [2 stages (2S) and 3 stages (3S)] and conventional open-sun (OS) drying. The experiments were carried out under the conditions of ADS rubber drying with temperature of 30-60°C. Initial moisture contents of sample rubber were varied between 20 and 50% dry-basis. The final moisture content for each drying strategies was fixed at 1±0.05% dry-basis. The experimental drying results were mathematical simulated by 7 common non-linear empirical models. The results showed that fresh rubber sheets drying with OS technique took longer drying time than those of solar and biomass drying. And the simulated data using approximation of diffusion model was the best fitting to experimental data of rubber sheet. Effective diffusivity of ADS rubber was also determined using the 2^nd Ficks law of diffusion and conclusion was that effectice diffusivity was dependent on drying temperature and was in order of 10^-7 m²/s. With various drying strategies, the results showed that specific energy consumption of 3-stages ADS rubber drying had a relatively low compared to the other drying techniques.

Abstract: Switch open fault characteristics and simple diagnosis scheme in a back-to-back converter are presented for a permanent magnet synchronous generator (PMSG) based variable-speed grid-connected wind power conversion. In the back-to-back converter, the failure in switching devices may occur either in a machine side converter (MSC) or in a grid side converter (GSC), which decreases the generator output power and degrades the stability in wind power generation system. To detect such a fault, the second-order harmonic components of the q-axis current are monitored in the MSC as well as in the GSC. To verify the effectiveness of the proposed scheme, the comparative simulation results are presented.

Abstract: According to the analysis of the network topological structure, an improved backward/forward sweep algorithm was proposed. The algorithm can be applied for weakly meshed distribution systems with distributed generation (DG). The method developed an incidence matrixbranch current-bus current injection matrix. A meshed network was converted to a radial network by breaking the loops at the ending nodes of link branches. The mathematical models of DG were established as PV and PQ node. For PV nodes, this paper used a dummy node and dummy branch which inject reactive power to the specified node to maintain the specified voltage value. IEEE 33-bus test feeder was used to verify the correctness and convergence of the proposed algorithm. Moreover, the impact of both weakly meshed and DG on voltage profile and convergence was also investigated.

Abstract: In order to solve the variable speed control as non-linear in wind energy application, it is important to obtain wind energy efficiently. And it is also effective in suppressing output fluctuation. Therefore, it will become a main torque system in the wind generation. The main object of this paper is to present a developed non-contact torque sensor for applying of non-linear control in the wind generator. In this paper, it examines whether efficient torque measurement of output shaft in the wind generation would be maintainable by non-linear control methods.

Abstract: Dynamic model based on screw theory and Lagrange’s equations including dynamic of servo motor rotor of a 3-DOF cable-driven surgical instrument was established in this paper. Overall dynamic of the 3-DOF cable-driven surgical instrument was performed by dynamic model of the open-loop chain surgical instrument after removal of cables and pulley, the mapping relationship model between the joint space and cable space, and rotor dynamic modeling of servo motor, which is the basic of investigating the overall responses and prosperities of surgical instrument.

Abstract: A distributed control system applied to small humanoid robots is designed in this paper, using ARM embedded processor and modular function approaches. The system designs plenty of hardware circuits to promote operability of system and reduce difficulties in development. This design solves the problems of high cost, low scalability, weak autonomy of small humanoid robot control system, providing a reliable experimental platform for further study. The feasibility of this control system will be verified through walking experiment of biped robot.