Design of electrically small wire antennas using a pareto genetic algorithm

We report on the use of a genetic algorithm (GA) in the design optimization of electrically small wire antennas, taking into account of bandwidth, efficiency and antenna size. For the antenna configuration, we employ a multisegment wire structure. The Numerical Electromagnetics Code (NEC) is used to predict the performance of each wire structure. To efficiently map out this multiobjective problem, we implement a Pareto GA with the concept of divided range optimization. In our GA implementation, each wire shape is encoded into a binary chromosome. A two-point crossover scheme involving three chromosomes and a geometrical filter are implemented to achieve efficient optimization. An optimal set of designs, trading off bandwidth, efficiency, and antenna size, is generated. Several GA designs are built, measured and compared to the simulation. Physical interpretations of the GA-optimized structures are provided and the results are compared against the well-known fundamental limit for small antennas. Further improvements using other geometrical design freedoms are discussed.     

Removal of manganese from water using combined chelation/membrane separation systems.

The addition of the chelating polymer polyacrylic acid (PAA) to assist in the removal of manganese from groundwater by membranes was investigated using membranes with different pore sizes under various operating conditions. Negligible manganese removal was achieved with the UF and NF membranes at acidic pH values, but removals exceeding 90% could be achieved at elevated pH (pH 9), presumably due to the formation of manganese hydroxides. Mn removal increased substantially when PAA was added to the feed solution, due to chelation of Mn by the PAA and rejection of the chelates by the membranes. The chelate could be broken at acidic pH, releasing free PAA that could then be separated from the Mn ions and reused. Smaller PAA molecules were lost in the first regeneration cycle, but negligible PAA was lost in subsequent cycles. In the systems with PAA, nitrate ions were rejected more efficiently than in the PAA-free systems, presumably because of electrical repulsion between nitrate ions and PAA sorbed on the membrane surface. With increasing PAA dose, the volumetric flux first decreased and then increased; the latter result was accompanied by a change in the physical-chemical form of the polymers, as indicated by an increase in turbidity.     

Minor constituents of palm oil

Crude palm oil contains about 1% of minor components including carotenoids, tocopherols, sterols, triterpene alcohols, phospholipids, glycolipids and terpenic and paraffinic hydrocarbons. The nutritionally important components such as carotenes and tocopherols also improve stability of the oil. Although a highly valued product, carotene unfortunately is bleached or destroyed in refining because suitable recovery technology is not available. Thermal degradation of carotene, previously suspected of giving rise to undesirable chemicals, now is known to furnish mainly harmless hydrocarbons, most of which are removed by the deodorization step in refining. Tocopherols, being natural antioxidants, need to be carefully preserved during milling, refining, fractionation and modification of palm oils. The accumulation of tocopherols in the palm fatty acid distillate promises to provide a new source for the recovery of this valuable substance. The role played by phospholipids is frequently misunderstood because they can act in two ways, i.e. as an antioxidant synergist and a surface active agent to disperse impurities in oil. In crude palm oil the phospholipid content is small, because most of it is removed during milling; the phosphorus content is due mainly to inorganic phosphorus. Among the sterols, cholesterol constitutes too small a percentage to be of much concern. Sterols, triterpenoids and terpenoid hydrocarbons are also potentially useful side products should recovery technology become available. Other newly characterized minor and trace components also are discussed.     

基于NI软件和硬件的监测系统

正新加坡政府于2007年投入3.5亿新加坡元用于将城市改造为全球清洁能源枢纽,其重点是开发太阳能。为了实现这个目标,新加坡政府和经济发展局下属的清洁能源研究与实验计划(CERT)制定了多项措施。为此,我们开设了含有五种不同光伏面板的太阳能科技中心,功率总计达14.2 kW。中心用于展示不同的并网光伏系统,并作为研究热带气候条件下不同光伏模块长时间运行的悭能和特性的测试实验中心。     

Processor scheduling and allocation for 3D torus multicomputersystems

Multicomputer systems achieve high performance by utilizing a number of computing nodes. Recently, by achieving significant reductions in communication delay, the three-dimensional (3D) torus has emerged as a new candidate interconnection topology for message-passing multicomputer systems. In this paper, we propose an efficient processor allocation scheme-scan search scheme-for the 3D torus based on a first-fit approach. The scan search scheme minimizes the average allocation time for an incoming task by effectively manipulating the 3D information on a torus as 2D information using a data structure called the CST (Coverage Status Table). Comprehensive computer simulation reveals that the allocation time of the scan search scheme is always smaller than that of the earlier scheme based on a best-fit approach. The difference gets larger as the input load increases, and it is as much a factor of 3 for high load. To investigate the performance of the proposed scheme in different scheduling environments, we also consider a non-FCFS scheduling policy along with the typical FCFS policy. The allocation time complexity of the scan search scheme is O(LW²H²). This is significantly smaller than that of the existing scheme which is O(L⁴W⁴H⁴). Here, L, W, and H represent the length, width, and height of 3D torus, respectively     

Intergranular Strain Evolution in a Zircaloy-4 Alloy with Basketweave Morphology

A Zircaloy-4 alloy with Widmanst?tten-Basketweave microstructure has been used to study the deformation behavior at the grain level. The evolution of internal strain and bulk texture is investigated using neutron diffraction and conventional microscopic techniques. The macroscopic behavior and intergranular strain development, parallel and perpendicular to the loading direction, were measured in situ during uniaxial tensile loading. It was observed that twinning plays a major role in both microstructural changes and polycrystalline plasticity.     

Complexity reduction of digital filters using shift inclusive differential coefficients

We present a graph theoretical methodology that reduces the implementation complexity of the multiplication of a constant vector and a scalar. The complexity of implementation is defined as the required amount of computations like additions. The proposed approach is called minimally redundant parallel (MRP) optimization and is mainly presented in a finite impulse response (FIR) filtering framework to obtain a low-complexity multiplierless implementation. The key idea is to expand the design space using shift inclusive differential coefficients (SIDCs) together with computation reordering using a graph theoretic approach to obtain maximal computation sharing. The problem is formulated using a graph in which vertices and edges represent coefficients and computational cost (number of resources). The multiplierless solution is obtained by solving a set cover problem on the vertices in the graph. A simple polynomial run time algorithm based on a greedy approach is presented. The proposed approach is compared with common-subexpression elimination to show slightly better results and is combined with it for further reduction of complexity. Simulation results show that 50-60% complexity reduction is achieved by only applying the MRP algorithm, and 70% complexity reduction is obtainable by combining it with common-subexpression elimination under a delay constraint of two or three.     

The optimization of conditions for the production of acid-hydrolysed winged bean and soybean proteins with reduction of 3-monochloropropane-1,2-diol (3-MCPD)

Response Surface Methodology (RSM) was used to establish the optimum time and temperature for production of acid‐hydrolysed winged bean protein (aHWBP) and acid‐hydrolysed soybean protein (aHSBP). Seven hours of hydrolysis at 125 °C was the optimum condition for producing aHWBP, whereas it was 5 h of hydrolysis at 125 °C for production of aHSBP. Although aHWBP and aHSBP produced using these conditions had favourable sensory qualities, they were found to have up to 25 mg kg^?1 of 3‐monochloropropane‐1,2‐diol (3‐MCPD). This exceeds the maximum level permissible in Commission Regulation (EC) No 466/2001. However, additional alkaline thermal treatment at pH 8.5 for 2 h at 100 °C effectively reduced the 3‐MCPD contents of aHWBP and aHSBP to undetectable levels. aHWBP has a distinctive flavour, which is different from that of aHSBP. The former has higher mean scores for meaty and vegetable attributes but lower mean scores for soy, umami and beany attributes than the latter.     

Improvement of linewidth enhancement factor in 1.55-μmmultiple-quantum-well laser diodes

The improvement of the linewidth enhancement factor in complex-coupled laser diode (CC-LD), or loss-coupled, was confirmed by measuring the spontaneous emission spectra below threshold from the sidewall of laser diodes. In addition, the serial resistance of the device was measured. The linewidth enhancement factor is improved by the presence of a light absorbing InGaAs grating for loss coupled distributed-feedback (DFB) laser diode (LD). We report the comparison of the linewidth enhancement factors of Fabry-Perot (FP) LD, conventional DFB-LD, and loss coupled DFB-LDs