The V-scope ultrasonic motion monitor: ergonomics applications in occupational manual materials handling and clinical exercise therapy

In this paper application is made of a three-dimensional telemetric ultrasound motion analysis technology originally designed for experimentation in the physics laboratory. When applied to human motion analysis in ergonomics, sports science and orthopaedic rehabilitation, this system offers great promise of solving problems hitherto insoluble or too costly to address.     

High-efficiency input coupling into optical waveguides using gratings with double-surface corrugation

Waveguide grating couplers that have surface corrugation on both boundaries of the waveguide were fabricated by the deposition of waveguide material at high-vacuum pressures onto a surface-relief grating etched into the substrate. A lateral shift between the two gratings along the direction of the common grating vector was created during the waveguide deposition when the substrate normal was tilted with respect to the direction of material deposition. A series of waveguide thicknesses having an identical angle of deposition were examined to observe the effect of the waveguide thickness, and corresponding lateral shift, on the branching ratio and input-coupling efficiency. Branching ratios of above 98% and input-coupling efficiencies near the theoretical limit for an incident Gaussian beam were obtained.     

Single-pulse, two-line temperature-measurement technique using KrF laser-induced O(2) fluorescence

A new single-pulse, two-line laser-induced O(2) fluorescence (LIF) temperature-measurement technique was demonstrated. The fluorescence spectrum obtained with multichannel detection following simultaneous excitation of two coincident transitions in the 0-6 and the 2-7 bands of the B(3)Σ(-)(u)-X(3)Σ(-)(g) Schumann-Runge system was used to determine the gas temperature. The rms error of 100-pulse average LIF temperature measurements, referenced to their corresponding thermocouple measurements, was 1.3% over a temperature range of 1300-1800 K in atmospheric air. Photon shot noise was found to be the primary source of uncertainty for these measurements in a quiescent environment. Single-pulse temperature-measurement uncertainties (1 σ) ranged from approximately 13% at 1300 K to 7% at 1800 K.     

环氧松香封端有机硅聚合物的合成及性能研究

以松香为原料先制备了环氧松香酰氯,然后以二甲基甲酰胺为溶剂,与羟基硅油通过酰化反应合成了环氧松香封端有机硅聚合物。研究了反应温度和物料配合比对合成反应的影响,并对产物进行了红外光谱(FT-IR)分析和热失重分析。实验结果表明:环氧松香酰氯与羟基硅油的质量配合比为2.2∶1,吡啶用量为松香酰氯的10%(wt,质量分数),反应温度40℃,反应3h条件下,松香封端有机硅聚合物的产率达到90.1%,黏度达到158.2mPa·s,环氧值达到0.156mol/100g。红外光谱(FT-IR)和环氧值分析测试表明在环氧松香引入了聚硅氧烷结构,热失重表明环氧松香封端有机硅聚合物具有较好的热稳定性能。     

On the futility of blind search: an algorithmic view of "no free lunch"

The paper is in three parts. First, we use simple adversary arguments to redevelop and explore some of the no-free-lunch (NFL) theorems and perhaps extend them a little. Second, we clarify the relationship of NFL theorems to algorithm theory and complexity classes such as NP. We claim that NFL is weaker in the sense that the constraints implied by the conjectures of traditional algorithm theory on what an evolutionary algorithm may be expected to accomplish are far more severe than those implied by NFL. Third, we take a brief look at how natural evolution relates to computation and optimization. We suggest that the evolution of complex systems exhibiting high degrees of orderliness is not equivalent in difficulty to optimizing hard (in the complexity sense) problems, and that the optimism in genetic algorithms (GAs) as universal optimizers is not justified by natural evolution. This is an informal tutorial paper--most of the information presented is not formally proven, and is either "common knowledge" or formally proven elsewhere. Some of the claims are intuitions based on experience with algorithms, and in a more formal setting should be classified as conjectures.