力标准机独立加码与逆程交换研究

静重式力标准机在施加递增或递减负荷过程中，当砝码进行逆程交换时会出现逆负荷现象。为此，提出了力标准机独立加码的概念与方法，建立并讨论了独立加码方法的驱动方式、砝码加卸过程的运动规律、加卸过程中吊挂受力变化、加载稳定性和工作效率问题。研究了通过少量砝码的合理组合与交换，实现多力级等力值间隔加载的技术方法。当砝码进行逆程交换时，为减小以至消除逆负荷现象进行了理论分析和实验验证。结果表明，提出的方法是可行的和有效的。为力基、标准机的技术发展和提高提供了一种新的理论方法和试验依据，对力值计量检测技术的进步具有重要意义。     

静重式力标准机独立加码过程仿真与优化分析

以100 k N的砝码加载过程为研究对象,从理论上提出一种消除逆程现象的方法。首先提出一种独立平滑加载方法,保证组合出的力值逐渐增大或者减小,使力值曲线平滑;并且建立数学模型,找到加载时进入平滑加载时间的有效区间;然后用Matlab进行仿真分析与优化。仿真优化结果表明:运用独立平滑加载从理论上可以消除逆程现象。     

力值计量标准现状及研究进展

在对比分析国际上各类力标准机计量性能的基础上,阐述了我国力值计量标准的研究现状及应用关键技术的先进性.提出并研制了基于静重式力标准机"独立加码"的技术与方法,解决了力标准机砝码逆程交换带来的负荷波动性过大的问题,为进一步研究砝码逆程交换产生的"逆负荷现象"提供了一种有效的技术方法.提出并研制了利用机械传动加载方式的叠加式力标准机,力传感器分组并联延伸力值的试验方法,以及力标准机参考标准量值溯源的方法,对研究建立新的大力值计量标准,具有参考和借鉴意义.     

静重式力标准机“逆程”现象的影响及消除

本文用详实的数据说明了静重式力标准机的“逆程”现象及对传感器检测结果的影响,介绍了电液伺服技术解决“逆程”现象的几个关键技术问题,肯定了电液伺服技术是消除“逆程”现象的一个行之有效的途径。     

基于Adams的静重式力标准机中心吊杆倾斜摆动影响因素分析

针对2MN静重式力标准机,利用Adams软件进行中心吊杆倾斜摆动影响因素分析,并研究减小摆动影响的方法。考虑偏移角度、砝码质量以及砝码加载位置等为影响因素,研究不同加载状态对加载值和稳定时间的影响。提出利用吊杆底部增加质量和阻尼的方法来减小这种影响,提高设备的准确度和稳定性,结果表明此种方法能有效缩短力值稳定时间。     

EJⅡ-1型静重式力标准机一种常见故障的分析与改进

EJⅡ-1型静重式力标准机作为一种测力标准设备,因具有诸多优点而在国家力值量值传递中起到重要作用,但其长期使用后会出现重复性降低的问题。本文通过对EJⅡ-1型静重式力标准机设计思路的研究,分析了重复性降低问题产生的原因,并提出了一种改进方案,以恢复设备的计量性能。     

静重式力标准机砝码在线称量方法的研究

本文介绍了一种在线称量静重式力标准机砝码的方法,该方法通过设计一种新的静重式力标准机砝码现场称量装置,可在不拆卸砝码的情况下,完成静重式力标准机砝码的称量.     

静重式力标准机结构稳定性研究

通常在进行静重式力标准机设计时,设计者主要考虑设备的强度及刚度.实验发现,在一定条件下强度及刚度符合要求的力标准机使用中会发生结构失稳现象.作者通过理论分析和实验研究,用解析法解决了静重式力标准机的结构稳定性设计问题并取得了满意的应用效果,为静重式力标准机尤其是小量程标准机的设计和制造提供了一种有效的方法.     

500kN静重式力标准机技术改造项目通过专家验收

由浙江省称重技术研究所和浙江大学机械电子控制工程研究所共同主持完成的５００ｋＮ静重式力标准机技术改造项目２０００年１０月２３日顺利通过专家验收。来自浙江大学、中国计量学院、浙江工业大学、中国计量科学研究院等单位的７位专家应邀参加了该项目的验收。专家委员会主任委员、中国计量学院副院长侯宇教授主持了此次专家验收会。５００ｋＮ静重式力标准机是浙江省称重技术研究所最主要的大型测力设备 ,也是华东地区同量级测力设备中准确度最高的设备。该设备１９７９年立项研制 ,１９８９年投入使用 ,十年来为全省传感器的科研测试…     

静重式力标准机砝码交换力平衡控制技术

静重式力标准机利用少量的砝码，进行相等力值间隔逐级加、卸荷时，需要交换砝码。当砝码进行交换时出现逆负荷现象，会对被检测力仪的示值产生影响。阐述了静重式力标准机采用的交换砝码方法是建立在利用弹性力替代砝码重力，砝码交换过程中重力与弹性力达到平衡的基本原理。提出了实现静重式力标准机砝码交换时系统达到力平衡的一种预加荷装置，经砝码交换力平衡控制的力学分析与实验验证，静重式力标准机采用预加负荷实施倒码力平衡控制的方法在理论上和技术上是可行的、有效的。     

Design and analysis of single-cell capture microfluidic device

The aim of our study was to develop microfluidic devices using microchannel technology with the capability of capturing single cells. We analyzed and compared the cell-capturing efficiencies of series-loop microchannel and parallel-loop microchannel devices that were produced using polydimethylsiloxane (PDMS). Each set of microchannels was composed of a main flow channel and several branch channels with capturing zones. The microfluidic devices were designed to use the differences in flow rates between the main flow channel and the branch channels as a means of capturing single cells based on size and sequestering them within the microstructure of multiple capture zones. The data indicated that the flow medium encountered significant resistance in the series-loop microchannel device, which resulted in an inability to hold the captured cells within any of the capture zones. Flow resistance was, however, greatly reduced in the parallel-loop microchannel device compared to the series-loop device, and single cells were captured in all the capturing zones of the device. Our data suggest that the parallel-loop microchannel technology has significant potential for development toward high-throughput platforms capable of capturing single cells for physiological analyses at the single-cell level.     

Towards a device independent digital image processing software for photoelastic analysis

The application of digital image processing (DIP) techniques to photoelasticity has greatly simplified data reduction and analysis. The softwares reported so far are hardware dependent and hence not portable. A simple PC based device independent software for collection of photoelastic data from digitised fringe patterns is presented. The software is validated by evaluating the near crack tip stress field parameters for a crack subjected to mode I and mode II loadings.     

新型封隔器胶筒防突装置的设计及分析

为了防止封隔器胶筒在大间隙和高压差工况下肩部突出,提高封隔器的封隔能力,针对传统防突装置的不足设计了一种伞式完全防突装置。首先,使用有限元软件对无防突装置、安装部分防突装置和使用完全防突装置的胶筒在封隔大间隙工况下的密封性能进行了对比分析,发现使用完全防突装置时胶筒的最大Von Mises应力最小、封隔能力最强。其次,介绍了伞式防突装置的结构和工作原理,对其机构进行了分析。同时设计了一款适用于Y111-150型封隔器胶筒的伞式防突装置,验证了机构不会发生自锁,各零部件之间也无干涉发生。当防突装置翼板展开防突时,连杆两端处的销钉受力最大,此处易发生失效;当防突装置用于大间隙、高压差封隔时可适当增加这2处销钉的直径和连杆的厚度。研究结果对封隔器防突装置的设计具有一定参考意义。     

城市生活垃圾压缩设备的压头及箱体设计与分析

针对目前城市生活垃圾压缩设备普遍存在压缩效果不够理想的问题,提出一种新型压头和箱体结构,给出一种压缩效果和密闭性较好的城市生活垃圾压缩方式.通过优化传统垃圾压缩设备压头的结构,设计一种推铲形新型压头装置,提高垃圾压缩设备的压缩倍数,改善垃圾的压缩效果.对现有压缩设备箱体的结构和污水排放口进行了改进,设计一种与推铲形压头相匹配的垃圾压缩设备新型箱体.采用有限元分析方法,对设计的推铲形压头装置和箱体进行了分析.分析结果表明,同目前垃圾压缩设备使用的平压头和楔形压头相比较,设计的推铲形压头具有更好的压缩效果,为城市生活垃圾压缩设备压缩装置的设计和制造提供了理论基础.     

Design of flexible plant layouts

In this paper, we present an approach for the design of plant layouts in stochastic environments. We consider systems where the, product mix and product demand are subject to variability and where duplicates of the same department type may exist in the same facility. In contrast to a job shop layout, we allow these duplicates to be placed in non-adjacent locations on the plant floor and for flow allocation between pairs of individual departments to be made as a function of the layout and the product demand realization. We present a scenario-based procedure that iteratively solves for layout and flow allocation. We show that having duplicates of the same departments, which can be strategically located in different areas of the plant floor, can significantly reduce material handling cost while effectively hedging against fluctuations in flow patterns and volumes. We show that the effect of duplication is of the diminishing kind, with most of the cost reduction occurring with relatively few duplicates. We also show that the quality of the obtained layouts can be quite insensitive to inaccuracies in estimating demand scenario probabilities.     

Durable transparent carbon nanotube films for flexible device components

This paper describes a durable carbon nanotube (CNT) film for flexible devices and its mechanical properties. Films as thin as 10 nm thick have properties approaching those of existing electrodes based on indium tin oxide (ITO) but with significantly improved mechanical properties. In uniaxial tension, strains as high as 25% are required for permanent damage and at lower strains resistance changes are slight and consistent with elastic deformation of the individual CNTs. A simple model confirms that changes in electrical resistance are described by a Poisson's ratio of 0.22. These films are also durable to cyclic loading, and even at peak strains of 10% no significant damage occurs after 250 cycles. The scratch resistance is also high as measured by nanoscratch, and for a 50 μm tip a load of 140 mN is required to cause initial failure. This is more than 5 times higher than is required to cause cracking in ITO. The robustness of the transparent conductive coating leads to significant improvement in device performance. In touch screen devices fabricated using CNT no failure occurs after a million actuations while for devices based on ITO electrodes 400,000 cycles are needed to cause failure.These durable electrodes hold the key to developing robust, large-area, lightweight, optoelectronic devices such as lighting, displays, electronic-paper, and printable solar cells. Such devices could hold the key to producing inexpensive green energy, providing reliable solid-state lighting, and significantly reducing our dependence on paper.     

Random laser action from a natural flexible biomembrane-based device

Abstract

Incoherent random lasing action in flexible eggshell membranes infiltrated with rhodamine 6G laser dyes is demonstrated. Laser radiation is achieved by exciting samples with 1-ns pulses at 526 nm. A threshold of 58 μJ/pulse is measured for the samples. The minimum threshold decreases to 35 μJ/pulse after the sample is coated with gold nanoparticles using a magnetron sputtering technique. The peaks of emission spectra are observed to redshift from 576 to 596 nm as dye concentration rises from 0.03 to 0.6 wt%. A linewidth of approximately 5 nm is obtained for most samples. This study is expected to offer a new way to induce lasing emission using biological microfibrils, and enriches basic knowledge of biophotonics.     

Design and integration of flexible planar micro-supercapacitors

As promising candidates for energy-storage devices,supercapacitors (SCs) have attracted considerable attention because of their unique features,such as their high power density,outstanding rate capability,excellent cycling performance,and safety.The recent boom in portable electronic devices requires high-performance SCs that are flexible,simplified,thin,and integrated.Tremendous efforts have been directed towards the design and integration of planar microSCs (MSCs) based on different active electrode materials by various methods.This review highlights the recent developments in the device design of flexible planar MSCs and their integration with other electronic devices.The current challenges and future prospects for the development of flexible MSCs are also discussed.