A self-organizing fuzzy control of weld pool size in GMA welding processes

In arc welding processes, because of the complexity and nonlinearity of heat transfer phenomena, it is often difficult to design an effective control system based upon an exact mathematical model. In this paper, a self-organizing fuzzy control method is proposed to obtain a uniform weld quality by regulation of the surface temperature at a desired level. The proposed control system is designed to comprise a combined structure of the fuzzy SOC with conventional PD control for improving the system's stability. The control experiments show that the proposed controller guarantees a uniform weld quality for various welding conditions.     

Wear and Wear Transition in Silicon Carbide Ceramics during Sliding

Wear and wear transition in silicon carbide ceramics during sliding have been investigated. Three different microstructures, i.e., solid-state-sintered silicon carbide, liquidphase-sintered silicon carbide, and a liquid-phase-sintered SiC-TiB₂ composite, were produced by hot pressing. Wear data and examinations of worn surfaces showed that the wear behavior of these silicon carbide ceramics was significantly different. In the solid-state-sintered silicon carbide, the wear occurred by a grooving process. In the liqudphase-sintered silicon carbide and composite, on the other hand, an abrupt transition in the wear mechanism from an initial grooving process to a grain pullout process occurred during the test. The transition occurred significantly earlier in the composite than in the carbide. The different wear behavior in these silicon carbide ceramics is discussed in relation to the grain or interphase boundary strength.     

Performance of GaAs-AlGaAs V-grooved inner stripe quantum-well wirelasers with different current blocking configurations

GaAs-AlGaAs V-grooved inner stripe (VIS) quantum-well wire (QWW) lasers grown by metalorganic chemical vapor deposition with different current blocking configurations, n-blocking on p-substrate (VIPS), p-n-p-n blocking on n-substrate (VI(PN)_nS) and p-blocking on n-substrate (VINS) have been fabricated and characterized. The VIPS QWW lasers show the most stable characteristics with effective current confinement: one of the lasers shows fundamental transverse mode, lasing up to 5 mW/facet, typical threshold current of 39.9 mA at 818.5 mm, an external differential quantum efficiency of 24%/facet, and characteristic temperature of 92 K. The current tuning rate was almost linear at 0.031 mm/mA, and the temperature tuning rate was measured to be 0.14 nm/°C. Comparison of the light output versus current characteristics of the lasers with different current blocking configurations is presented here     

Pollutant dispersion over two-dimensional hilly terrain

Numerical prediction of the wind flow and pollutant dispersion over two-dimensional hilly terrain is presented. The wind tunnel experiments are conducted to validate the numerical results of the flow field. Measured mean velocity profiles, turbulence characteristics, and surface pressure distributions show good agreement with the numerical predictions. The hypothesis of Reynolds number independency for an atmospheric boundary layer flow over aerodynamically rough terrain is numerically confirmed. The linear theory provides generally good prediction of speed-up characteristics for gently sloped low hills. The effect of two-dimensional double hills on the dispersion of pollutants from continuously or temporally released line source of different emission heights and locations is also investigated. The ground-level concentrations are considerably reduced as emission heights are increased. The variances of ground-level concentration with respect to time from a temporally released source are strongly influenced by the flow separation.     

拉西瓦高拱坝岩体力学、工程地质研究成果综述

拉西瓦水电站高拱坝建基岩体工程地质、岩体力学研究是中国水电顾问集团2004年度专题科研成果之一“高混凝土拱坝建基岩体工程地质、岩体力学综合研究”的主要成果,其重点内容为岩体风化、卸荷、岩体质量级别的定量划分、河谷应力场分带、建基岩体主要岩体力学参数研究,坝肩抗滑稳定、开挖后综合检测验证等;在理论探讨、方法实践、预测验证和创新尝试等方面取得了一定成果,具有一定的社会、经济效益。     

Analysis of color symbology from the perspective of cultural semiotics focused on Korean costume colors according to the cultural changes

The purpose of this study was to analyze the symbolization of colors as cultural codes, based on costume colors. In order to study the significance of colors in cultural changes, we carried out a quantitative analysis and interpreted it from the perspective of cultural semiotics. The range of this study was focused on Korean costume colors, over diverse diachronic stages of Korean culture. For this study 1535 color samples were collected, measured with a spectrophotometer, and analyzed quantitatively according their diachronic stages of origin. As a result, red, blue, and yellow were found to be the most frequently used colors during the Chosun Dynasty, a period based on Confucianism. These colors acted as cultural codes with cultural significance. During the Modern times pink, light blue, and black increased in frequency and represented the reception of western culture, the changing sex role of women in society, and utilitarianism. In these days, neutral colors and grayish tones of all colors are the most significant colors of high frequency. The use of such colors is closely related to industrialization, mechanization, functionalism, and the changes of women's sex roles in the societies. They are used as cultural codes, especially to emphasize a rational and masculine image rather than a feminine image. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 71–79, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20290     

A micromachined electrochemical sensor for free chlorine monitoring in drinking water.

In this work, we designed, fabricated and tested a disposable, flow-through amperometric sensor for free chlorine determination in water. The sensor is based on the principle of an electrochemical cell. The substrate, as well as the top microfluidic layer, is made up of a polymer material. The advantages include; (a) disposability from low cost; (b) stable operation range from three-electrode design; (c) fluidic interconnections that provide on line testing capabilities; and (d) transparent substrate which provides for future integration of on-chip optics. The sensor showed a good response and linearity in the chlorine concentration ranging from 0.3 to 1.6 ppm, which applies to common chlorination process for drinking water purification.     

Operation of a nonlinear optical loop mirror with orthogonally polarized waves in nonpolarization-preserving, single-mode fiber

We demonstrate stable operation of a NOLM using orthogonally polarized control and signal beams in nonpolarization-preserving, single-mode fiber. The NOLM can transcribe data from an optically incoherent input at one wavelength to a coherent output over a range of wavelengths. Operation of the NOLM without tuning for the input bit rate is possible over a range of bit rates from less than 1 Gb/s to more than 50 Gb/s.     

Volumetric three‐dimensional up‐conversion display medium

Abstract— Several rare‐earth‐doped fluoride crystals that are excited to emit visible light by sequential two‐photon absorption have been investigated as display‐medium candidates for static volumetric three‐dimensional displays. Dispersion of powders of these materials in a refractive‐index‐matched polymer is reported because such a medium may result in a scalable display. The scattering problem in such a medium is greatly reduced by index‐matching the polymer to the crystalline particles. An index‐matching condition that optimizes the performance is identified.