Analysis of Laser-Induced Plume During Disk Laser Welding at Different Speeds

During high power disk laser welding, the high-speed photography was used to measure the dynamic images of the laser-induced plume at different laser welding speeds. Various plume features (area, height and brightness) were extracted from the images by the color space clustering algorithm. Combined with observation on the surface and the cross sections of welding samples, the effect of welding speed on welding stability was analyzed. From the experimental results, it was found that these features of plume could reflect the welding state. Thus changes of the plume features corresponded to different welding speeds, which was helpful for monitoring the laser welding stability.     

INTRAPARTICLE MASS TRANSFER IN THERMALLY REGENERABLE ION EXCHANGER

An intraparticle mass transfer model was developed for a thermally regenerable ion exchanger which is coagulated by weak acidic and basic microspheres. It was assumed that salt diffuses (hrough macropore and microspheres in the radial direction of a resin particle. Uptake curves were measured not only in [R_aCOOH + R_bN] + NaCl ) [R_aCOONa + R_bNHCl] system but also in [R_aCOO²²Na⁺ + R_aN] + Na⁺ )[R_aCOONa⁺ + R_bN] + ²²Na⁺ and [R_aCOOH + R_aN] + HCl ) [R_aCOOH + R_bNHCl] systems. Macropore diffusivity D_p.Na, tortuosity factor τ_p and diffusivity through weak acidic microspheres D_a,Na were obtained from the isotopic ion exchange. The uptake curves of HC1 gave diffusivity through weak basic microspheres.D_b,Hcl The experimental uptake and desorption curves of NaCl agreed fairly well with the theoretical values. Diffusions through both macropore and microspheres were significant. The diffusivity through microspheres D_b,Nacl NaCI are smaller than D_a,Na. and can be estimated by D_bHcl approximately.     

重粒子射线照射系统及其应用

在许多领域中,重离子辐射系统都是非常有用的工具.自1981年以来,癌症一直是日本死亡率最高的疾病,人们十分关注发展新的癌症治疗技术,重离子辐射技术是目前最先进的无创伤癌症治疗技术,它利用重离子辐射癌变组织进行病灶治疗.该方法有两个优点:其一是重离子束高度集中在癌变部位,对其周围的正常组织的毒性最小;其二是碳离子较X射线和γ射线有更强的生物学效应,且这种效应在癌变部位治疗非常方便和有效.2007年群马大学与地方合作共同建设世界最先进的重离子辐射装置,2009年将投入使用,2010年试运营.该设施是世界具有相同功能治疗系统中最小型化的装备,尺寸为45m×25m,包括可将碳离子加速到70%光速的20m加速器.在癌症治疗方面,该系统是日本大学与地区合作的先进综合治疗体系的核心设施.     

基于旋转GAUSS曲面体热源模型的激光焊接热过程的数值模拟

利用旋转GAUSS曲面体新型热源模型,忽略深熔激光焊时小孔对传热的影响,建立了移动激光热源作用下的三维数学模型.采用PHOENICS3.4软件,模拟了SUS304不锈钢深熔激光焊接热过程的温度场和熔池熔合线形状,得到了激光深熔焊接时的温度场分布规律和"钉头"状的熔池形状,数值模拟结果与实验结果基本吻合.     

Volatile Flavor Components of Chive (Allium schoenoprasum L.)

Using well-established techniques, a sample was obtained of the steam volatile oil of chive (Allium schoenoprasum L.). A total of 30 components were identified and the neutral oil contained mainly sulfur compounds (16.8%). The most important constituents are dipropyl disulfide, methyl pentyl disulfide, pentyl hydrodisulfide and (cis and trans) 3,5-diethyl-1,2,4-trithiolane. Methyl pentyl disulfide and pentyl hydrodisulfide have not been described previously.     

Some optimization problems for timed marked graphs

Discrete event dynamic systems are frequently encountered in complex man-made systems. Such a system is often described in terms of a timed Petri net. For periodic behaviour of such a system, a timed marked graph provides a convenient and powerful tool of modelling and analysis. In this paper we define three optimization problems for such a system. All of these problems are formulated as mixed integer linear programming (MIP) problems. To improve computational efficiency, we introduce ‘cuts’ to these MIP problems, and the effect of such cuts is examined through computational experiments on some test problems.     

High Efficiency Drive Method of an Open‐Winding Induction Machine Driven by Dual Inverter Using Capacitor Across dc Bus

This paper proposes a highly efficient drive method for an open‐winding induction machine with a single constant voltage source and a single capacitor. By focusing on the phase voltage of the open‐winding machine, which is determined by the phase difference and the dc voltage of each power converter, it is possible to control the peak value of the phase voltage by controlling the voltage of the capacitor. Thus, a reduction in the iron loss due to harmonic voltage in the open‐winding machine is expected. In the proposed method, the voltage of the capacitor is controlled by the difference between the two reference voltages of the power converter, which depends on the machine power factor and the phase difference of the power converter connected to both ends of the winding. Based on experimental results, the converter loss and the machine loss can be reduced by controlling the voltage of the capacitor in accordance with the machine speed using the proposed method.     

激光深熔焊熔池X光图像恢复与特征分析

X光对于焊件具有很强的穿透性,可以利用其观测和分析激光深熔焊过程焊件内部熔池形态以及匙孔能量传递效果,实现对焊接过程有效地实时监测.在大功率光纤激光焊接304不锈钢过程中,由于X光图像采集过程中的噪声干扰,导致熔池X光图像存在严重退化现象,清晰度不高,识别性较差.为此研究一种图像恢复和增强算法,对熔池X光退化图像进行恢复和增强处理,使其在处理后能够更好地被识别.以盲去卷积法试验估计出熔池X光图像退化的点扩散函数,并以此函数为参数对熔池X光图像进行维纳滤波恢复,再进行灰度变换以增强图像,进而对熔池动态特性进行分析.结果表明,所提出的方法能够有效改善激光焊过程熔池X光图像质量,突出熔池边缘轮廓特征.     

One role of titanium compound particles in aluminium nitride sintered body

Microstructure of titanium compound particle in polycrystalline aluminium nitride (AlN) has been investigated using micro-auger electron spectroscopy (μ-AES). AlN-0.5 wt% TiO2-1.5 wt% Y2O3-0.4 wt% CaO system was sintered at 1850°C in nitrogen atmosphere using a graphite furnace. The AES studies show that the composition of the titanium compound particle is titanium, aluminium, carbon, oxygen, nitrogen and calcium. On the other hand, no calcium is observed by AES in the AlN grains and grain boundary. It is found that one role of the titanium compound particle is to trap calcium included in polycrystalline AlN. This revised version was published online in November 2006 with corrections to the Cover Date.     

Study on a Voltage Estimation of Tap‐Changing Transformer in Consideration of SVC Introduction

Recent years, installation of photovoltaic (PV) system is active by the environmental problem and feed in tariff system. Due to PV's output fluctuation, the static var compensator (SVC) made by power electronics technology is planning to install in distribution system. The SVC is expected for maintain the voltage. But SVC differs in a theory of operation of the existing voltage controller load ratio control transformer (LRT) and step voltage regulator (SVR). Because the SVC operation makes the system impedance changes, the existing voltage controller may not operate effectively. In this study, the intelligent‐control method which used the radial basis function (RBF) network is proposed. This method can reduce the effects of the SVC operation by including the performance characteristics of SVC in the conventional method. An advantage of unnecessary arrangement attention of the SVC setup node and easy cooperation with the existing equipment is obtained by applying this method.