Developing alternative devices to the long-term urinary catheter for draining urine from the bladder

The self-retaining urinary catheter is used for long-term drainage of urine from the bladder only as a last resort because of serious associated complications, yet it remains a routine method for managing older and disabled patients with loss of bladder control. Blockage of the catheter from calcified deposits within its lumen is a common occurrence, obstructing the passage of urine and causing an urgent, unpredictable problem for patients, carers and the nursing staff. The need for further research on the subject has been recognized for many years. The SuPort Project aimed to develop an alternative suprapubic urine collection system. This report outlines the approach adopted towards the design and selection of the novel device, the production problems that ensued and the small clinical trial of a modified prototype.     

The behaviour of hydrostatic pads with grooved lands

A hydrostatic pad is usually made up of a recess surrounded by a land. Viscous fluid is supplied under pressure to the recess. The land, being separated from the bearing surface by a relatively small clearance, will act as the hydraulic impedance needed to separate the required bearing pressure inside the recess from the pressure of the surrounding environment. If the pad is moved relative to the bearing surface, the film of fluid in the clearance, being viscous, will be sheared. This shearing action will initiate viscous shear stresses between the fluid layers and hence viscous drag between the moving pad and the bearing surface. The lands of the pad, having a much smaller clearance from the bearing surface, will be subjected to a much higher drag force than the recess. The power required to overcome such a drag force, and cause the required motion of the pad relative to the bearing surface, will be transformed mainly into heat. Sometimes, especially under high relative speeds and with small clearances, the generated heat can be detrimental to the bearing action, and if excessive, may lead to bearing failure.     

Water-jet-assisted diamond disk dressing characteristics of CMP polishing pad

This paper presents an experimental investigation of the dressing characteristics of a porous polishing pad using a combination of water-jet dressing (WJC) and traditional diamond disk dressing (DDC). The WJC and DDC dressing mechanisms were integrated in order to improve the dressing efficiency. The pad recovery test was performed. In this test, the real-time friction force was determined, scanning electron microscope images were obtained, and the dressed surface topography after prolonged operation without conditioning was examined. The pad cut rate and the rate of removal of the copper substrate by the polishing process were investigated by comparing the results of the WJC?+?DDC, only DDC, and only WJC methods. The experimental results showed that although the WJC can remove the slurry residue from the pad surface and consumes less pad material, it cannot remove the glazed layer formed as a result of plastic deformation, which contributes to the low material removal rate. On the other hand, DDC can remove the glazed layer of the pad and restore the pad asperities; however, a few residual chips still remain on the sides of the pores or inside the pores. WJC?+?DDC cannot only remove the embedded slurry particulates and the glazed layer, but also remove the slurry residue accumulated on the pad surface and restore the pad asperities. In addition, the chip residues in the pores, created by the diamond grit, are completely removed by the WJC?+?DDC conditioning process; the removal of the chip residue helps in obtaining the highest material removal rate. In summary, WJC?+?DDC can be used as an effective pad conditioning method.     

Deformation of large liquid crystal display glass sheets across a gap between noncontact transportation devices

In recent years, large mother glass sheets with high resolutions have been used for electric devices, such as television panels, personal computer monitors, and cell phones, particularly to reduce manufacturing costs and improve production efficiencies. Accordingly, high-speed inspection processes for detecting defects in thin-film transistor arrays using charge coupled device (CCD) cameras have become very important, and a noncontact transportation technique for the high-speed inspection section is necessary to avoid damage to the glass sheets during inspection processes. Furthermore, a gap of around 100 mm between transportation devices is needed for the inspection area of the CCD cameras to project an inspection light from underneath the glass sheet. This means that the capability to make a large, thin glass sheet jump over the gap is required for the noncontact transportation device.In this paper, an air-levitating transportation device that had air-supply pads with orifice restrictors and vacuum ports was proposed to support a 500 mm square, liquid crystal display glass sheet. The deformation of the glass sheet supported by the proposed transportation device was investigated numerically and experimentally when the glass sheet jumped over the gap between the proposed devices. In addition, the optimum combinations of air supply and vacuum pressures and their areas in the proposed device were studied for obtaining the largest jumping distance of the thin glass sheet. It was found that by properly selecting supply and vacuum pressures and their areas, the largest jumping distance supported by the proposed device could reach approximately 75 mm.     

Simple high vacuum evaporation system with low-temperature substrate

An ultrahigh vacuum system has been constructed which permits deposition of thin films onto 4.2-K substrates. The evaporation mechanism is contained within a small cylindrical vessel which is totally immersed in liquid (4)He. This device has been used to study superconductivity in PbBi and Ga, PdH and PdD, and most recently, transport properties of ultrathin films.     

针对液体介质的磁性液体旋转密封技术概述

磁性液体是一种功能材料,既具有液体的流动性,又具有固体磁性材料的磁性,在密封中的应用是其最成功的应用之一。磁性液体密封作为高新密封技术,被广泛应用在军工、化工、航空航天等领域。目前,磁性液体密封技术在密封气体介质和真空中的研究已经趋于成熟,相比之下,对液体介质的密封还存在很大局限性。从磁性液体与被密封液体介质的界面稳定性、界面破坏过程以及用于液体介质的密封装置结构设计三方面,对磁性液体旋转密封技术的研究进展进行阐述,总结三类用于液体介质密封的磁性液体密封结构设计方法的技术特点和缺点,最后对磁性液体在液体介质密封中的前景作出展望。     

Preparation and assessment of frozen-hydrated sections of mammalian tissue for electron microscopy and X-ray microprobe analysis

A system is described for preparing and examining frozen-hydrated sections of mammalian tissue, using commercially available equipment. An essential part of the system is a liquid nitrogen cooled vacuum transfer system. Minor modifications were required to interface the various manufacturers' equipment, and also to facilitate handling of specimens in the cryoultramicrotome. A variety of criteria indicates that our sections are truly frozen-hydrated, but negligible image contrast in the sections is a serious problem both for morphological work and X-ray microanalysis.     

Surface finishing method for tooth flank of heat-treated surface-hardened small gears using a gear-shaped tool composed of alumina-fiber-reinforced plastic

High-accuracy gears are necessary to ensure the strength and silence of compact geared motors. Heat-treated surface-hardened small gears are employed in the reducer of a compact geared motor. The heat treatment causes distortion, which deteriorates the gear accuracy. To remove this distortion, surface-hardened small gears are rehobbed with a carbide hob. The rehobbing makes a tool mark on the gear tooth surface. This tool mark leads not only to strength deterioration of the tooth surface, but also vibration and noise. Therefore, a surface finishing method that eliminates the tool mark is required. However, it is difficult to finish surface-hardened small gears. This study proposes a tooth surface finishing method for a surface-hardened small gear. The method employs a gear-shaped tool composed of alumina-fiber-reinforced plastic (ALFRP) and a surface finishing device with an oscillation/traverse system. The proposed method was used in an experiment to remove the tool mark on the gear tooth flank of a surface-hardened small gear rehobbed by the carbide hob. The effectiveness of this method was verified. In addition, the processing mechanism of the ALFRP gearshaped tool was analyzed by observing the tool and the chips.     

A statistical model for material removal prediction in polishing

This paper develops analytically a statistical model for predicting the material removal in mechanical polishing of material surfaces (MS). The model was based on the statistical theory and the abrasive–MS contact mechanisms. The pad-MS and pad-abrasive-MS interactions in polishing were characterised by contact mechanics. Two types of active abrasive particles in the polishing system were considered, i.e., Type I – the particles that can slide and rotate between the pad and MS, and Type II – those embedded in the pad without a rigid body motion. Accordingly, the material removal is considered to be the sum of the contributions from the two types of abrasive interactions. It was found that the mechanical properties and microstructure of the polishing pad and polishing conditions have a significant effect on the material removal rate, such as the porosity and elastic modulus of the pad, polishing pressure, volume concentration of abrasives, particle size, pad asperity radius and pad roughness. It was also found that different types of active particles contribute quite differently to the material removal. When the mean particle radius is small, the material removal is mainly due to the Type II particles, but when the mean particle radius becomes large, the Type I particles remove more materials. The model predictions are well aligned with experimental results available in the literature and can be used for the material removal prediction in chemo-mechanical polishing if a proper treatment of the chemical effect is introduced.     

A system for automated disassembly of snap-fit covers

This paper reports on a prototype automated system for the disassembly of batteries from a family of electronic devices whose plastic, snap-fit covers house AA or AAA batteries, such as remote controls and calculators. Included in the development of the prototype system was the design of a disassembly tool that uses three force-sensing resistors to provide force feedback information. A pneumatically actuated vacuum gripper and electromagnet system was also developed for recovering the snap-fit cover and batteries once they were released by the disassembly tool. The disassembly module was mounted on the tool head of a three-axis translational motion robot, and a Visual Basic application was developed to interface and control the robot with a Galil digital motion controller. A model-based computer vision application was also developed in Visual C++ using a Kinect sensor and the Open Source Computer Vision library to identify and localize the electronic device placed on the disassembly robot. Using the information gathered by the model-based computer vision application, the robot was able to use the disassembly tool module to perform the necessary disassembly operations to remove the device’s snap-fit cover and batteries. The design of such a disassembly system could aid the future development of fully autonomous disassembly systems that can handle a broader range of electronic products.     

Frozen-surface replicas of rat bladder luminal membrane

A method for preparing replicas of the luminal surface of frozen, unfractured but deep-etched whole bladder tissue using a Bullivant type II device is described. A small piece of glutaraldehyde-fixed (uncryoprotected) rat bladder is rinsed in distilled water, mounted luminal side uppermost on a specimen holder and rapidly frozen by immersion in liquid nitrogen (cooled below its boiling point in a vacuum) or by contact with a copper block at liquid nitrogen temperature. The specimen is processed in the type II device without fracturing and 'deep-etched' by allowing a longer period than usual to elapse before shadowing. The results are assessed with reference to the appearance of the luminal membrane in standard freeze-fracture replicas, and some preliminary observations on the structure of the normal luminal membrane and its counterpart in bladder tumours are presented.     

可移动燃油自动加注装置设计

为了解决某特种装备缺少高效安全可靠的燃油自动化加注装置的问题,提出了一种可移动燃油自动加注装置的设计方案。针对加注装置对其机械系统进行了设计,利用触摸屏和接口控制技术设计了加注装置的电控系统。电控系统硬件基于西门子触摸屏和S7-200 Smart PLC,使用触摸屏编写软件WinCC flexible SMART V3及下位机PLC程序编写软件STEP7-Micro/WIN SMART编写算法程序来完成数据的采集和控制等功能,并通过以太网接口实现上位机触摸屏和下位机PLC之间的实时通信。结果表明,设计的可移动自动加注装置高效、安全、可靠,且定量加注精度达到±0.3%,为液体加注提供了一定的方法和参考。     

颗粒物塑形负压吸盘的设计与研究

 在气压传动系统中，负压吸盘是实用有效的真空元件。大多数负压吸盘针对平面形接触面而设计，无法保证粗糙表面的气密性。为解决这一问题，提出一种基于颗粒物塑形原理的负压吸盘。该吸盘利用刚度可控的阻塞技术，将颗粒物填充于硅胶软膜内，并在软膜内部镶嵌类软骨结构。当吸盘与平面物体接触时，硅胶气囊充气膨胀并贴合物体表面三维轮廓。完全贴合后固化颗粒物并利用负压实现适形吸附式夹持，适用于多种材质和形状的表面。通过对光滑表面物体和粗糙表面物体的吸附测试，验证了吸盘的气密性和适形能力。负压塑形吸取技术方案可为气动真空元件的设计提供有益参考。     

Mechanisms of Chemical-Mechanical Polishing of SiO2 Dielectric on Integrated Circuits

One of the fundamental mechanisms of chemical-Mechanical polishing (CMP) is the mechanical interaction between the wafer and polishing pad. This interaction was simulated in experiments. The vertical displacement of the wafer with respect to the polishing pad, the fictional drag of the wafer against the pad, and the pressure of the slurry trapped between the wafer and pad were measured. These experiments were performed over a range of commercially common CMP conditions. In addition, polishing rates were measured for CMP performed under induced hydrodynamic conditions where the wafer was separated from the pad by a film of slurry.

It was found that no appreciable polishing occurred under hydrodynamic CMP conditions. Under commercial CMP conditions, it was found that the wafer contacts the polishing pad asperities as evidenced by near-zero wafer displacement and high friction coefficients (?0.4). It was also found that pad conditioning (intentional roughening) causes a suction force to develop between the wafer and pad. This suction force draws the wafer into further contact with the pad, by as much as 20 μm, and corresponds to peak slurry vacuum pressures of 12 kPa (1.7 psi).     

Modeling and simulation of material removal in planarization process

In planarization processes, material removal analysis is essential to the estimation of the wear rate and non-uniformity. A model that describes the material removal of a pad with rough surface grinding by using abrasive grains is developed. A collection of micro-contact spots is identified and the deformation approach is subsequently calculated. Elastic-plastic theory and the wear model are used to construct the expression for the magnitude of material removal as a function of the indentation depth. First, the indentation depth of micro-contact spots in the asperity of the pad and the deformation of the flat part of pad are obtained by using elastic-plastic theory. Then, the material removal caused by individual micro-contacts is calculated with the help of wear theory. Finally, the macroscopic wear volume is found by summing the volumetric wear of each individual micro-contact. Moreover, the pad dressing process is introduced to demonstrate the developed model for material removal. A parametric study is conducted to explore the influence on the material removal results and the planarization interfacial phenomena of operational parameters. These parameters compose of the applied down force, rotational speed of dresser, and the density of abrasive grains. The results provide a detailed picture of the interface phenomena and yield an insight into the physical effects of the operating parameters in the planarization processes.     

Concepts for validating intelligent process measurements

With increased automation, operational validation is vital for effective control, maintenance and management of industrial plants and processes. Validation should be traceable, starting from the interface to the process up to the highest level of operations. At present, validation is focused at the systems level and current methods are based on condition monitoring, and fault detection and isolation techniques using functional, analytical and hardware redundancy. With the focus at the systems level, redundancy methods exploit integration and fusion of information from multiple measurement devices, and thus tend to disregard validation of the operation of the individual devices themselves. Transducers and sensors provide an interface to the process and produce measurement information. Validation of the measurement output from a sensor is imperative in situations where the cost of redundancy may be prohibitive. This paper presents concepts for validating measurements made with intelligent devices. The proposition is that an intelligent device should provide both measurement and condition information. The condition information should be used to assess the validity of the measurement by identifying metrics which describe the sensor and process conditions, respectively. This is the lowest level of validation because it occurs at the interface with the process being monitored. The information required for this level of validation can be obtained by utilizing all the components of the signal produced by a sensor, providing that the sensor has a wide frequency response. An example of a validation approach which follows from this argument is briefly described.     

氟化镁窗口氘灯的真空辐射衰减特性

针对真空环境下使用氟化镁窗口氘灯时,氘灯表面易受污染,导致氘灯的紫外-真空紫外辐射强度逐渐衰减的问题,对紫外-真空紫外波段辐射传递标准光源氘灯的真空辐射衰减机理进行了分析.在此基础上,研制了液氮制冷屏装置来抑制氘灯衰减.建立了氘灯真空辐射特性测试系统,利用该系统对液氮制冷屏装置的有效性进行了考察.测试结果显示,在160～300 nm波段,氘灯平均衰减率可由原来的7%/h下降为1%/h,表明液氮制冷屏装置能有效地抑制氟化镁窗口氘灯在真空环境下的辐射衰减.     

指端可穿戴式力触觉交互装置设计与评估

可穿戴式力触觉交互技术作为力触觉交互技术的一个分支,可以为操作者提供更为真实、自然的人机交互体验。设计了一种指端可穿戴式力触觉交互装置,装置由穿戴于腕部的控制盒以及穿戴于指尖的部分组成,穿戴于指尖的部分重约30 g,尺寸为38 mm×31 mm×50 mm。装置采用连杆机构,可实现三自由度的力触觉反馈。装置使用蓝牙通信,具有小型轻便、穿戴方便的特点。通过方向感知与识别实验证明,装置可在指腹面产生8个有效的方向性信息,而且每个方向都可以为人所正确感知。此外,虚拟环境交互实验证明,装置可帮助人在虚拟环境中控制交互力的大小,并提高人机交互的效率。     

氟化镁窗口氘灯真空辐射衰减特性研究

对氟化镁材料窗口、紫外-真空紫外波段辐射传递标准光源氘灯的真空辐射衰减机理进行了分析。在此基础上，研制了液氮制冷屏装置来抑制氘灯衰减。建立了氘灯真空辐射特性测试研究系统，利用该系统对液氮制冷屏装置的有效性进行了考察。测试结果表明，在160-300nm波段，氘灯平均衰减率可由原来的7%/h下降为1%/h。液氮制冷屏装置能十分有效的抑制氟化镁窗口氘灯在真空环境下的辐射衰减。     

Evaluation of the performance variation of porous air pads on discontinuous surfaces

A new high accuracy position measurement system has been developed. It measures the position of a 0.1 mm diameter copper-beryllium wire that informs alignment of energy beams in advanced particle accelerators. This new measurement system employs air pads to provide precision and friction free rotation of a sensor. To enable the measuring system to be positioned over the wire, a slot is required in the measuring device rotor. To optimise the design of this measuring system it was necessary to understand the performance of the air pads as they pass over the gaps (slots) in the rotor. This paper describes modelling and experiments that were performed to gain understanding of air pad performance when encountering such a surface gap. Particularly, an analytical model of the variation of load of a 20 mm × 40 mm porous air pad during the passing of a 1.5 mm wide slotted surface. Subsequent experimentation revealed that the general behaviour of the load variation had been captured effectively. The results of this analysis reveal that air pads of this size can reliably pass above an opening of this size with about 14% reduction in force. The results and the methodology presented in this paper can be used as an effective basis for future designs and studies.