微纳V槽脆/塑性域切削的3D激光检测及评价

针对微纳米级功能V槽微细加工及评价困难的问题,采用单点金刚石切削方法在超精密机床上对光学玻璃进行V槽的微纳尺度加工,且利用非接触激光检测技术展现V槽的加工形貌。研究目的是分析V槽的微纳米尺度加工的可行性以及找出如何评价V槽加工精度的方法。首先,采用单点金刚石在光学玻璃上进行V槽的微纳尺度切削试验。然后,利用3D激光超精密检测仪器检测加工的V切痕,构建微V槽切痕的形貌图,建立V槽形状误差PV值和V槽尖角圆弧半径的评价模式。最后,分析在微纳尺度加工中切除深度与V槽角度的形成机理以及切削深度对V槽形状误差及其尖角圆弧半径的作用机制。结果表明,在亚微米级尺度加工中存在一个脆/塑性域切除加工状态转变的临界切削深度。在塑性域切削中,金刚石刀具尖角形状可以复制到工件表面,形成深度小于0.386μm、形状误差PV值约0.103μm、尖角半径约为0.182μm的V槽。此外,V槽形状误差PV值在塑性域切除加工中始终保持不变,但在脆性域切除加工中随着切削深度增大而逐渐剧烈加大。而且,V槽尖角圆弧半径在塑性域切削中随着切削深度减小而减小,但为了获得完整的V槽轮廓还需被控制在V槽成型临界界线以下。因此,在处理非接触激光检测的3D数据的基础上,V槽形状误差PV值和尖角圆弧半径可以用来评价V槽微纳尺寸加工的加工精度和微细程度。     

Dielectric Recovery Characteristics after High‐Frequency Current Interruption in Vacuum Circuit Breaker

When the contacts of circuit breaker are opened just before current zero, the gap between contacts will still be very short. Therefore, it cannot withstand recovery voltage between the contacts. In such a case, multiple reignition is likely to take place. Many investigators had tried to clarify this phenomenon, and many reports have been published. However, high‐frequency current interruption and dielectric recovery characteristics are related to some parameters (value of current, arc time, and so on). In addition, arc phenomenon has also been implicated. Hence, it is difficult to understand this phenomenon accurately. In this paper, we conducted dielectric recovery test and high‐frequency current interruption test. Further, we conducted observation experiment using vacuum chamber in order to investigate the effect of small dc current. At the end, we calculated plasma density in the electrodes after high‐frequency current interruption by considering the result of observation experiment and dielectric recovery test.     

Robust control for a constantly rising temperature system (Hm control approach)

Thermoluminescence dating has attracted the attention of geology and archaeology researchers as a new method. This method requires a heating device to raise the temperature of the specimens at an exact rate. This paper describes the design method of a control system that can achieve this goal. This control system lends to be unstable because of the existence of the parameter perturbation and dead time. In this paper, the perturbation and dead time are treated as perturbations of a nominal plant regarded as a first-order lag time system. Improvement of tracking characteristics in the low-frequency domain and robust stability in the high-frequency domain of the control system are achieved by using the solution of the mixed-sensitivity problem that is a kind of H^∞ control theory. Experiments verify the effectiveness of this method.     

金刚石砂轮的ECD修锐和整形研磨及其对硬脆材料的加工

为研究金属结合剂金刚石砂轮切削刃修锐整形对硬脆材料加工表面形态的影响,先通过接触放电法对SD600金属结合剂砂轮切削刃进行修锐,再用整形研磨方法对砂轮表面金刚石磨粒的不同切削刃高度进行整形研磨,最后用修整好的砂轮磨削加工用于光学设备的硼硅玻璃、石英玻璃、石英晶体和蓝宝石等几种硬脆材料.结果表明:硬脆材料粗糙度的改善程度...     

Structural Optimization of Autonomous Energy Networks by Mathematical Programming Techniques

The renewal of conventional energy systems is important countermeasures against global warming effects and natural hazards. A self‐sustainable decentralized energy system is one of the promising solutions for future sustainable and resilient societies. In this paper, a mathematical programming model is formulated and design and utilization of the overall energy network is optimized based on the model, where stationary batteries are equipped. Through some numerical simulation results, the effectiveness and the potential, for example, for clarifying the effect of the batteries, of the proposed model are investigated.     

金刚石砂轮金属结合剂的气中单脉冲电火花放电去除机理

针对金属结合剂金刚石砂轮修锐困难的问题,提出采用气中电火花接触放电修锐的方法。为有效地实现微细金刚石砂轮的修锐,建立单脉冲电火花放电去除加工的试验系统,研究金属结合剂的气中和液中电火花放电去除机理。在试验研究中,主要分析无负荷电压和放电极性对脉冲放电电流、脉冲放电间隙、脉冲放电去除量、电极磨耗比等的影响。结果表明,正极性不易发生短路现象,而且气中的脉冲放电间隙小于液中的 ,适应于微细金刚石砂轮的修锐。此外,在气中放电中存在由绝缘破坏引起的火花放电向附有电弧柱的电弧放电转变的临界无负荷电压,且电火花放电的去除量可以明显小于电弧放电的去除量,但是当无负荷电压小于某一定值时电极消耗比会快速增加。修锐的试验结果显示,利用气中单脉冲电火花放电去除加工条件可以实现金属结合剂微细金刚石砂轮的修锐,产生较好的砂轮出刃形貌,改善磨削表面质量。     

Development of Magnetic Levitation System for Science and Technology Education: Magnetic Levitation Control by Using a Hall Element Displacement Sensor with Neural Network

In this study, we developed a magnetic levitation system using a Hall element displacement sensor with neural network for science and technology education. The sensor configured with three Hall elements was devised in order to measure displacement from an electromagnet to a levitated object with a permanent magnet. Use of the Hall element displacement sensor achieves a lower cost magnetic levitation system. Furthermore, three‐layered feedforward neural network was utilized in order to improve the precision of the Hall element displacement sensor. Finally, operation verification of the developed magnetic levitation system was conducted by designing state feedback regulator with observer.     

Preparation of ZnS and CdS fine particles with different particle sizes by a spray-pyrolysis method

In the preparation of ZnS and CdS fine particles by an ultrasonic spray-pyrolysis method, the particle size was changed from submicrometre to micrometre size by changing the concentration of the metal nitrates in the starting aqueous solution containing Zn(NO3)2 or Cd(NO3)2 and SC(NH2)2. The effects of temperature profile in the reactor furnace on the properties of prepared particles were also investigated by varying the temperature profiles: constant and increasing temperature distributions. The volume mean diameter of the prepared particles was found to be approximately proportional to the one-third power of the concentration of the metal nitrates in the solution. The crystalline phase and fluorescence properties of ZnS and CdS particles did not depend on the particle size. This revised version was published online in November 2006 with corrections to the Cover Date.     

Analysis of Aldehyde-bisulfites in Beer by HPLC-Fluorescence Detection with Post-column Derivatization

An analytical method was based on the aldehyde-bisulfite (separated by HPLC) reaction with o-phthalaldehyde in the presence of ammonium acetate, producing a fluorescent compound. Detection limits of alkanalbisulfite (from formaldehyde- to octylaldehyde-bisulfite) and 2-alkenalbisulfite (from trans-2-hexenal- to trans-2-nonenal-bisulfite) ranged from 5 nM to 25 nM. The method was less sensitive for free sulfite (detection limit 100 μM) than for aldehyde-bisulfite. Increasing acetaldehyde-bisulfite with addition of 25 mM acetaldehyde to a beer sample showed free sulfite in the beer. Free sulfite and acetaldehyde-bisulfite were detected in commercial beers but other aldehyde-bisulfites were not.