Advanced Materials Research Vols. 622-623

Abstract: Taking taper-lock Connection in Wind Turbine Spindle as research object, the paper analyzes the relativity of structural sizes and builds the parametric structural model by means of a way APDL. By using the non-liner finite element software ANSYS, the stress of taper-lock on the limit load conditions is analyzed, then contact stress and strain of the planet carrier and spindle are discussed. This is useful to the choice of assembly condition during taper-lock, planet carrier and spindle and providing theoretical data.

Abstract: Sea waves are a very promising energy carrier among renewable power sources, and so many devices to convert wave energy into electrical energy have been invented. This paper discussed the fundamentals of ocean wave energy, summarized the wave energy research being conducted. And the purpose is to take refers to scientists and engineers in this area.

Abstract: We applied an effective medium model for a computational study and investigated a recombination mechanism in a P3HT:PCBM bulk heterojunction (BHJ) organic solar cells where the main assumption is the p-n nanostructure is treated as one single effective semiconductor layer, and parameters in this configuration are fed into a standard solar cell device simulator, called a Solar Cell Capacitance Simulator (SCAPS). Using SCAPS, the electrical performances of organic solar cells and the intensity-dependent current density -voltage (J-V) were simulated and compared with the actual experimental result. The results show that they are in good agreement with each other and monomolecular recombination mechanism is the dominant mechanism in the BHJ organic solar cells.

Abstract: The cascading reservoirs in Perak, Malaysia, were used to test the sensitivity analysis of hydroelectric power generation during refill and deplete period of the reservoirs. The cascading scheme comprises four reservoirs namely Temenggor, Bersia, Kenering and Chenderoh. The test was conducted after the analysis of water balance and stage-storage relationship of each reservoir in the cascading scheme. The result showed that power generation from the smaller reservoir, Bersia, is more sensitive to the change of headrace level, while the larger storage capacity and rated head reservoir is the most sensitive to the change of release. Therefore, to maximize the power generation from the cascading reservoir, the refill operations should be ranked according to the increasing order of the reservoir storage capacity and a reverse order should be followed during deplete period.

Abstract: This paper presents a non-divergent power flow using homotopy continuation method for power system static analysis. During power flow calculation with newly established network data in power system planning, divergence may occur because of the ill-condition by singularity of power flow Jacobian or bad initial guesses. The application of homotopy continuation method can lead the chosen initial guess to a closer solution to power flow equations in hybrid coordinate successfully and can provide further information on the convergence characteristic. This paper includes an illustrative example certifying the effectiveness of the proposed method.

Abstract: In this study, energetic based fluid selection for a solid oxide fuel cell-organic rankine combined power system is investigated. 9 dry organic fluids with varied critical temperatures are chosen and their corresponding ORC cycle performances are evaluated at different turbine inlet temperatures and exhaust gas temperature (waste heat source) from the upper cycle. It is found that actual ORC cycle efficiency for each fluid strongly depends on the waste heat recovery performance of the heat recovery vapor generator. Exhaust gas temperature determines the optimal fluid which yields the highest efficiency.

Abstract: In this paper, a hybrid optimization method, GA-SQP, is presented in which the genetic algorithm (GA) is a stochastic method is combined with the sequential quadratic programming (SQP) method, which is a deterministic method. The power system stabilizers parameters tuning problem is converted to an optimization problem which is solved by hybrid GA-SQP optimization algorithm. The New England 10-unit 39-bus standard power system, under various operation conditions, is employed to illustrate the performance of the proposed method. The results are very encouraging and suggest that the hybrid GA-SQP algorithm is very efficient in damping improvement of the power system.

Abstract: Thermal degradation is an attractive way to eliminate poly(methyl methacrylate) (PMMA) waste to which high temperatures are applied in the absence of oxygen. However, the process is not selective, resulting in a complex composition of products. Catalytic degradation over zeolites provides an effective route to selectively convert PMMA into desired products at lower temperatures, since zeolites have high acidity and shape-selectivity. In this work, the degradation of PMMA over various zeolites, including ZSM-5, BETA and USY, has been investigated in a batch reactor as a feasibility study to recover methyl methacrylate (MMA) as well as other valuable chemicals. The results showed that PMMA can be completely degraded at 300 oC and MMA was recovered as light oil. With increasing the degradation time, PMMA was converted over zeolites into more gaseous and light oil products, while the thermal degradation gave higher portion of heavy oil. From GC-MS analysis of light oil, MMA was found as the main product, co-existing with methyl 2-methyl propionate and methyl 2-methyl butyrate both of which can be used as synthetic fragrance.

Abstract: In the present work, shell, which is available in abundance, low cost and non-toxicity, was used as a source of calcium for preparation of heterogeneous base catalysts. The catalyst was prepared by dissolution-precipitation method in which a calcined shell was mixed with Zn(NO₃)₂ and Al₂O₃ under acidic conditions, followed by calcination at 300-700 °C. ZSA-I was referred to as the catalyst attained under the suitable synthesis conditions. Physicochemical properties of ZSA-I were studied by using X-ray fluorescence spectroscopy (XRF), powder X-ray diffraction (XRD), thermogravimetric/ differential thermal analysis (TG/DTA) and CO₂-pulse chemisorption analysis. ZSA-I gave the highest fatty acid methyl ester yield of 99 wt.% in the transesterification of palm oil with methanol and can be reused at least 5 times with a retention of the methyl ester yield higher than 96 wt.%.

Abstract: The main motivation of this work was to obtain high efficiency at reduced CdTe absorber layer thickness and replacing Zn_xCd_1-xS as window layer in conventional CdS/CdTe solar cells. The conventional CdTe baseline case was the starting point of this investigation to analyze ultra thin and high efficiency Zn_xCd_1-xS/CdTe solar cell for optimal value of x. The initial step of the analysis was to decrease the CdTe absorber layer to the extreme limit of 1 µm and at this thickness the proposed cell has shown satisfactory level of efficiencies. The ultimate step was to insert a suitable back surface field (BSF) with As₂Te₃ to reduce the back contact barrier height and back surface recombination loss of the ultra thin cell. All the analysis was done using the widely used simulator Analysis of Microelectronic and Photonic Structures (AMPS 1D). The conversion efficiency of 18.02% (Voc = 0.89 V, Jsc = 25.34 mA/cm2, FF = 0.78) without BSF and an efficiency of 20.3% (Voc = 0.93 V, Jsc = 25.97 mA/cm2, FF = 0.825) with As₂Te₃ BSF were achieved for the proposed cells from 1 µm and 0.6 µm CdTe absorber layer respectively. Moreover, the normalized efficiency of the proposed ultra thin cells linearly decreased with the increasing operating temperature at the gradient of -0.35%/°C, which indicates better stability of the ultra thin cells.