Optimal common-mode voltage reduction PWM technique for inverter control with consideration of the dead-time effects-part II: applications to IM drives with diode front end

The main theme of this paper is to demonstrate the applications of the newly developed common-mode voltage reduction pulsewidth-modulation (PWM) technique, which restricts the common-mode voltage to one-third of DC-link voltage, to vector-controlled induction motor drives. As compared to previous common-mode voltage reduction techniques, the presented technique can be applied to the inverter with diode front end and has no adverse effect on the linear modulation range. Therefore, vector-controlled drives using the developed technique for inverter control have a wide speed range. Moreover, the effects of the common-mode voltage reduction PWM technique on speed response for vector-controlled induction motor drives will be fully investigated in this paper. It will be demonstrated by intensive experimental results that speed performance does not deteriorate significantly within the rated speed range.     

On the Computational Complexity of Consumer Decision Rules

A consumer entering a new bookstore can face more than 250,000alternatives. The efficiency of compensatory and noncompensatory decisionrulesfor finding a preferred item depends on the efficiency of their associatedinformation operators. At best, item-by-item information operators lead tolinear computational complexity; set information operators, on the other hand,can lead to constant complexity. We perform an experiment demonstrating thatsubjects are approximately rational in selecting between sublinear and linearrules. Many markets are organized by attributes that enable consumers toemploya set-selection-by-aspect rule using set information operations. In cyberspacedecision rules are encoded as decision aids.     

A joint GA+DP approach for single burn-in oven scheduling problems with makespan criterion

This research is motivated by the scheduling problem found in the burn-in operation of semiconductor final testing, where jobs are associated with release times, processing times, and sizes. The burn-in ovens are modeled as batch-processing machines which can process a batch of several jobs as long as the total sizes of the jobs do not exceed the machine capacity, and the processing time of a batch is equal to the longest time among all the jobs in the batch. Moreover, this paper attempts to schedule jobs on a single batch-processing machine to minimize makespan. A joint GA+DP algorithm is proposed involving two stages: (1) the formation of job sequence by genetic algorithm operators, and (2) the formation of batches by a dynamic programming algorithm. Computational experiments are given to examine the performance of the proposed algorithm. The experimental results indicate that the joint GA+DP approach has well improved on all instances with respect to solution quality and runtime.     

Investigation of Ti Addition Effects on the Thickness of 55 pct Al-Zn-1.6 pct Si Coating by First-Principles Calculation

First-principles method was performed to predict the effect of Ti addition on thickness and adhesion of 55 pct Al-Zn-1.6 pct Si coating. The results of optimized geometric configurations, total energy, and charge distributions for the Ti substitution in Fe2Al5 and FeAl3 phases indicated Ti will grab electronic charges from Al atoms, form bonds with neighboring Al, which will reduce the growth of Fe-Al intermetallic layers, and finally enhance the adhesion of the coating/substrate. Furthermore, experiments were performed to validate the prediction results of first-principles successfully.     

Composite hydrogeological investigation and characterisation methods applied at a nuclear power plant site in Taiwan

Drawing from the lessons learnt from the Fukushima nuclear disaster in Japan, the assessment of subsurface environmental hazard around nuclear power plants has emerged as a critical task. Consequently, aiming to better understand the possible environmental impact of radiation leaks into the groundwater, a prescreening programme was initiated in 2011 by the Taiwanese government. As part of this programme, this study conducted various borehole prospecting techniques to identify in situ hydrogeological characteristics at Chin‐Shan Nuclear Power Plant. Borehole electrical log, sonic log and temperature/conductivity log were conducted to explain the regional lithologic conditions and permeability of the formation. In conjunction with this, the interwell tracer and pumping test was carried out to simultaneously determine the hydraulic parameters. In our opinion, the implementation of such in situ end‐to‐end investigations is essential in interpreting in situ fluid and solute transport dynamics prior to programming any numerical scheme for early warning, vulnerability assessment and regular monitoring of a nuclear power plant site.     

Effect of [6,6]‐phenyl‐C61‐butyric acid methyl ester on the morphology of poly(3‐hexylthiophene) film

The change of morphology of poly(3‐hexylthiophene) (P3HT) film as a result of blending with [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PCBM) was studied using a freeze‐dry method. A porous structure was observed as the P3HT/PCBM solution was freeze‐dried. The pore size decreased as the proportion of PCBM increased in the P3HT/PCBM blended film. Additionally, the freeze‐dried P3HT/PCBM film was more resistant to the formation of PCBM crystals than that prepared by a spin‐coating method during the thermal annealing process. Homogeneous distribution of PCBM in the freeze‐dried P3HT/PCBM film was the main reason for the reduction of large PCBM crystal formation. Copyright © 2011 Society of Chemical Industry     

A New Quality Improving Scheme for VQ Decompressed Images Based on DWT

The better compression rate can be achieved by the traditional vector quantization (VQ) method, and the quality of the recovered image can also be accepted. But the decompressed image quality can not be promoted efficiently, so how to balance the image compression rate and image recovering quality is an important issue. In this paper, an image is transformed by discrete wavelet transform (DWT) to generate its DWT transformed image which can be compressed by the VQ method further. Besides, we compute the values between the DWT transformed image and decompressed DWT transformed image as the difference matrix which is the adjustable basis of the decompressed image quality. By controlling the deviation of the difference matrix, there can be nearly lossless compression for the VQ method. Experimental results show that when the number of compressed bits by our method is equal to the number of those bits compressed by the VQ method, the quality of our recovered image is better. Moreover, the proposed method has more compression capability comparing with the VQ scheme.     

Geometrical effect on laminar mixed convection in the entrance region of shrouded arrays of heated rectangular blocks

Abstract

The effect of geometric parameter on laminar mixed convection in the entrance region of shrouded arrays of heated rectangular blocks is approached numerically for large Prandtl number fluid. The problem considered is related to convective cooling of electronic components mounted on horizontal circuit boards. Typical development of streamline and isotherm, block wall temperature distribution, and local Nusselt number are presented. It is found that the secondary flow leads to a significant enhancement in heat transfer. The multiple eddies above the block, induced by the combined geometric and buoyancy effect, lead to a more uniform block wall temperature distribution and then reduce the magnitude of the highest wall temperature.     

Effect of chlorine on the viscosities and structures of blast furnace slags

The viscosity of CaO–SiO₂–Al₂O₃–MgO–CaCl₂ slags (C/S?=?1.12) were investigated to elucidate the effects of chlorine ranging from 0.02 to 0.53?mass% on the blast furnace slags at high temperatures. Moreover, the Raman spectra of the quenched slags and the X-ray diffraction patterns of the slags cooled in air after viscosity measurement were thoroughly analysed to interpret the transformation of the structures of the slags with increasing the content of chlorine. The viscosity was found to decrease slightly with the increase of chlorine at a given temperature higher than 1673?K, and the critical temperature (T_CR) decreased from about 1660 to 1590?K simultaneously which was possibly deriving from the precipitation of Ca₂Al₂SiO₇, Ca₃Al₂(SiO₄)₃–xCl₄ x and SiO₂ in higher chlorine content. The degree of polymerisation for silicon–oxygen tetrahedra was found to decrease estimating from the decrease of the average amount of bridging oxygen calculated from the deconvolution results of the Raman spectra of the quenched slags, which provided the explanation for the decrease in viscosity. And that the apparent activation energy of the slags was commonly reduced by chlorine increasing demonstrated the decrease in the degree of polymerisation of molten slags simultaneously.     

Assessing the efficiency of supply chain scheduling algorithms using data envelopment analysis

Where different supply chain planning algorithms are used, generally similar results may pose some challenges on the differentiating powers of evaluating different production schedules because of the increasing complexity of a supply chain network structure. For the comparison purpose, performance evaluation of different supply chain planning algorithms aims to use different supply chains models with different demands, capacities, and commonality through efficiency perspective by using a modified network rational data envelopment analysis (DEA) model. The proposed DEA model has the abilities: (1) to treat only undesirable outputs that exist without normal output, and the situation where input and output are both zero by introducing two new parameters to denote the maximum inventory and amount of delayed demands of a given node in a given time period; and (2) to evaluate the effect of the undesirable outputs/inputs on efficiency with assumption that they leave the system at the end of the current time period and re-enter the system at the beginning of the next time period. To prove the effectiveness of this DEA model, eighteen scenarios with different demands, capacities, and multiple periods are compared. In addition, this study tests the DEA model on a wafer testing/probing operation of a leading global semiconductor manufacturing and testing company in Taiwan by internal supply chain perspective. Results show that the DEA model proposed in this study can be used to assess the efficiency of a real-world operation with undesirable outputs/inputs, such as inventory and delayed demands.