遥操作工程机器人系统临场感技术研究-6自由度临场运动感觉反馈技术的研究进展

 研究开发出一种遥操作工程机器人系统，可以应用于诸如火灾现场的修复作业等广阔的领域．该系统由伺服控制的工程机器人、2根从远处操纵工程机器人的操纵杆、视频系统和6自由度运动模拟器组成．操作者坐于座椅上，座椅固定于运动模拟器的上方． 该系统需要解决的一个关键问题是如何使操纵者高质量地获得工作现场的临场运动感觉． 提出了一种6自由度临场运动感觉反馈方法，其信号源来自工程机器人上安装的6个加速度传感器． 该方法的有效性已为实验所证明，即应用6自由度运动模拟器不但可以高质量地模拟工程机器人单个自由度的运动：滚动、俯仰、转动以及前后、左右、上下的平移，而且可以高质量地模拟工程机器人的各种复合运动．     

Theoretical model for flash generation

Reduction of flash generated in a gas vent is of great concern for manufacturers of electronic parts. The present study proposes a theoretical model for flash generation through consideration of flow characteristics in a gas vent. The model predicts the factors controlling flash, i.e., material parameters such as zero‐shear viscosity, crystallization temperature, thermal conductivity, and heat capacity, and process parameters such as injection and mold wall temperatures, packing pressure, and the clearance of a gas vent. On the other hand, we measure the amount of flash generated in the molding of poly(phenylene sulfide) (PPS) composites containing glass fiber and spherical fillers (CaCO₃ or Al₂O₃). Flash reduces with decreasing size of spherical fillers. These experimental data are successfully interpreted using the flash model. Polym. Eng. Sci., 45:198–206, 2005. © 2005 Society of Plastics Engineers     

Novel electro-optic properties of epitaxially grown (Pb, La)(Zr, Ti)O3 (PLZT) thin films derived by advanced sol–gel methods

Advanced sol–gel methods using a secondary solvent addition into (Pb, La)(Zr, Ti)O₃ (PLZT) sol–gel solution and a methanol pre-treatment of sapphire substrates are demonstrated. For the secondary solvent addition, the additive affected the crystallinity and electro-optic (EO) property of PLZT films and only methanol addition can improve them. In addition, the methanol pre-treatment is also appeared to be effective to improve film characteristics.

Through these optimizations, epitaxially grown PLZT thin films on r-cut sapphire are obtained and a high Pockels coefficient which is comparable to those of bulk PLZTs is achieved. It is believed that these PLZT thin films are applicable for integrated EO devices and open the door for the future data communication systems.     

CREEP-FATIGUE CRACK GROWTH AND FRACTOGRAPHY OF A TYPE 304 STAINLESS STEEL AT ELEVATED TEMPERATURE

Abstract— Creep-fatigue crack growth behaviour of a Type 304 stainless steel under four types of reversed loading patterns (P-P, P-C, C-P and C-C) was investigated and the results are discussed in the light of fracture mechanics and fractography. The crack growth rate for all of the four types of loading was successfully correlated in terms of the cyclic integral range λ J. It was unnecessary, for practical purpose, to divide Ay into a fatigue component, λ J _f, and a creep component, λ J _c, as has been done elsewhere. The transition of the correlating fracture mechanics parameter from fatigue to creep was not necessarily associated with the fracture morphology. This was related to the longer transition hold time in morphology in C-C type loading compared to C-P type loading, and was attributed to recovery of grain boundary sliding during the compression hold in the C-C type loading.     

Heavy arsenic doping of silicon grown by atmospheric pressure selective epitaxial chemical vapor deposition

Selective epitaxial Si with a high arsenic concentration of 2.2×10¹⁹ atoms/cm³ was deposited at a high growth rate of 3.3 nm/min under atmospheric pressure. It was confirmed that this method had excellent selectivity and produced films having good crystalline quality, abrupt dopant profiles at the interfaces, and smooth surfaces. The growth mechanism is discussed in terms of the relationship between the effects of arsenic surface segregation and etching by hydrogen chloride.     

Polarization-controlled single-mode VCSEL

Relative intensity noise (RIN) in a vertical-cavity surface-emitting laser (VCSEL) was greatly reduced through the use of polarization control to eliminate competition between two orthogonal polarization states by ensuring there was only one polarization state. Polarization was stable with optical feedback of up to 10%. Polarization control was achieved by inducing a small loss anisotropy in fundamental transversal mode VCSEL's. Anisotropic post structures, such as a rectangular post, an oblique post, or a zigzag-sidewall post, were found to be effective in creating loss anisotropy without serious degradation of other VCSEL characteristics such as light-output power or beam profile     

Inhibition of angiotensin-converting enzyme increases the nitric oxide levels in canine ischemic myocardium

Since angiotensin-converting enzyme (ACE) produces angiotensin II in the heart, ACE inhibitors may prevent coronary vasoconstriction and increase coronary blood flow. On the other hand, since ACE inhibitors also inhibit kininase II which results in reduced degradation of bradykinin, ACE inhibitors may increase cardiac nitric oxide (NO) levels via stimulation of bradykinin receptors. This study was undertaken to test whether ACE inhibitors increase the cardiac NO levels and coronary blood flow in the ischemic myocardium. In 34 open-chest dogs, the left anterior descending coronary artery was perfused through an extracorporeal bypass tube from the left carotid artery. When either imidaprilat or cilazaprilat of 3 microg/kg/min was infused into the bypass tube for 10 min after reduction of coronary blood flow due to partial occlusion of the bypass tube, coronary blood flow increased from 31 +/- 1 to either 45 +/- 5 or 43 +/- 4 ml/100 g/min despite no changes in coronary perfusion pressure (43 +/- 2 mmHg). During an infusion of either imidaprilat or cilazaprilat, bradykinin and the end-products of NO (nitrate + nitrite) concentrations of coronary venous blood were markedly increased, which were attenuated by either HOE-140 (an inhibitor of bradykinin receptors) or by N(omega)-nitro-L-arginine methyl ester (an inhibitor of NO synthase). We also observed increases in cardiac bradykinin and NO levels due to either imidaprilat or cilazaprilat in the low constant coronary blood flow condition. It is concluded that ACE inhibitors can increase cardiac NO levels via the accumulation of bradykinin in the ischemic myocardium.     

Investigation of the effect of surface phosphate ester dispersant on viscosity by coarse-grain modeling of BaTiO slurry

To understand the role of phosphate ester dispersant, we investigated the rheology of a BaTiO slurry. For the model case, a coarse-grain molecular dynamics (CGMD) simulation was performed with the butyral polymer didodecyl hydrogen phosphate (DHP) in the toluene/ethanol solvent. By systematically analyzing the effect of DHP from an atomic-scale first principle and from all-atom MD to microscale CGMD simulation, we investigated how the adsorption of a DHP dispersant on a BaTiO surface affects the microstructure rheology of a BaTiO slurry. The first-principle and all-atom MD simulation suggests that DHP molecules prefer to locate near the BaTiO surface. CGMD simulation shows a reduction in viscosity with an increase in dispersants, suggesting that the dispersant population near the BaTiO surface plays a key role in controlling the rheology of the BaTiO slurry. In this study, we propose an approach for understanding the BaTiO slurry with molecular-level simulations, which would be a useful tool for efficient optimization of slurry preparation.     

Comparison between SiO2 films deposited by atomic layer deposition with SiH2[N(CH3)2]2 and SiH[N(CH3)2]3 precursors

Thin SiO₂ layers were deposited by atomic layer deposition (ALD) using either Bis-dimethylamino-silane (BDMAS: SiH₂(N(CH₃)₂)₂) or Tris-dimethylamino-silane (TDMAS: SiH(N(CH₃)₂)₃) precursors. The purpose of this study is to evaluate these precursors for their suitability for ALD of hafnium (Hf)-silicate gate dielectrics. The advantages of these precursors are that the melting points and vapor pressures are moderate. The thickness of SiO₂ deposited using ALD process is controlled by the number of growth cycles and the growth rate was different for each precursor, that for BDMAS being 1.5 times that for TDMAS at the same reactor pressure. The carbon impurity in the SiO₂ film deposited using BDMAS was about half an order of magnitude less than that using for TDMAS. Furthermore, the carbon impurity was reduced to about the detection limit of secondary ion mass spectrometry after high temperature annealing at 1000 °C during 5 s.     

Surface modification of biodegradable plastics by ion beams

Biodegradable plastics can be used as conventional plastics, while on disposal they decompose to water and carbon dioxide by microorganisms existing in natural environment. Products using biodegradable plastics have recently been developed in many companies pursuing ecology. In this study, surface modification of biodegradable plastics was carried out by inert ion beams for improvement of photo deterioration under an ultraviolet ray. The hardness of biodegradable plastics tended generally to decrease with irradiation of an ultraviolet ray. In this method, the hardness of ion-bombarded biodegradable plastics was kept at an initial value under an ultraviolet ray, because the modified layer by ion bombardment intercepted an ultraviolet ray. The hardness of He⁺ ion-bombarded biodegradable plastics showed larger value than that of Ar⁺ ion bombardment. He⁺ ion bombardment at ion energy of 10 keV produced the suitable property with both of high transmittance of a visible ray and high interception of an ultraviolet ray in a surface layer of biodegradable plastics.