支持设计过程的装配可行域划分和零件定位求解

提出了支持设计过程的六种装配约束 ,根据装配约束的结合条件划分出装配可行区域、装配可能区域和装配不可行区域 .在装配可行区域的零件的位置是直接确定的 .在装配可能区域零件的位置要根据它们的约束组合条件和几何数据进行解释 ,然后计算零件的位置和方向 .在装配不可行区域 ,零件的位置不能求解 .装配可行区域的划分和零件位置的确定可以极高的效率支持产品的设计过程     

钢铁厂冶炼炉残铁的裸露爆破

为尽早完成高台裸露残铁的清除工程,采用爆破技术进行清除。通过局部试爆选择合理孔网参数,使用高精度导爆管雷管逐孔起爆网路,架设拦挡设施,取得了较好的爆破效果。爆破后,块度适中,碎块没有散落也没有飞出;厂房内实测振速0.76cm/s,小于安全允许振速,振动能量主要分布在20Hz以上高频部分高于建构(筑)物自振频率,未对周围建(构)筑物产生不良影响;施工用时短,为钢铁厂技改工程的提早竣工和钢厂正常生产的恢复争取了时间。残铁硬度高,钻孔速度慢,钻头、钎杆损耗大,但具有一定的可爆性,单耗仅为0.4kg/m3。可为类似工程的施工提供参考。     

钢铁厂冶炼炉残铁的裸露爆破

为尽早完成高台裸露残铁的清除工程,采用爆破技术进行清除。通过局部试爆选择合理孔网参数,使用高精度导爆管雷管逐孔起爆网路,架设拦挡设施,取得了较好的爆破效果。爆破后,块度适中,碎块没有散落也没有飞出;厂房内实测振速0.76cm/s,小于安全允许振速,振动能量主要分布在20Hz以上高频部分高于建构(筑)物自振频率,未对周围建(构)筑物产生不良影响;施工用时短,为钢铁厂技改工程的提早竣工和钢厂正常生产的恢复争取了时间。残铁硬度高,钻孔速度慢,钻头、钎杆损耗大,但具有一定的可爆性,单耗仅为0.4kg/m3。可为类似工程的施工提供参考。     

Computer-based FMS facilities design tool

FMS layout design is a complex process, involving a large number of alternatives, which contributes generously to the usual two-year FMS planning lead time. The need for a comprehensive, yet easy-to-use methodology or tool which can reduce this large number of alternatives to a more reasonable figure has motivated this research. A survey of existing FMSs was undertaken with the intention of identifying some of the more common (dominant) types of layouts, and to develop, if possible, a methodology for the selection of such layouts. However, almost every FMS was found to have a unique layout. For a given FMS under consideration, the capabilities with respect to the parts which can be manufactured is essentially given. The determining features of the resultant design of the FMS, therefore, are primarily based upon the design of the material handling system which integrates the FMS. However, as the number of machines in a FMS increase, the number of part sequences and alternate configurations increase at a dramatic rate. To assist in the preliminary design process, an interactive computer-based program has been developed to aid the search for non-inferior layouts to suit the exact part sequence needs of each FMS. Six criteria-three related to the distances parts travel during manufacturing and three related to the capital costs of the FMS-are provided to assist the user in selecting an appropriate arrangement. The program is described and its use is demonstrated in developing improved arrangements over an example FMS which was published in the literature. Although the reader is cautioned that the results were developed using only static measures, the results do indicate that significantly improved designs are possible using the proposed methodology     

Block-indexed solution of very large linear equation systems with symmetric dbbf coefficient matrix

The finite element solution of various partial differential equations leads to large linear equation systems, which may have a DBBF (double bounded band form) coefficient matrix, if periodicity conditions are taken into account. An efficient Fortran program solving such equation systems, developed for Control Data computers from the Cyber 70/170 series, utilizes the original block-indexed approach to reduce input-output time in communication with disc memory. Program performance is presented in some detail and quantitative comparison with other possible algorithms is carried out. An appendix lists the complete program.     

近江牡蛎16S rRNA基因片段序列变异分析

采用聚合酶链式反应(PCR)技术扩增了近江牡蛎Crassostrea rivularis(Gould)线粒体DNA16S rRNA基因,获得了大约为500bp的片段。PCR产物纯化后进行序列测定,经Clustal X同源排序,去除引物及部分端部序列,得到了415bp的核苷酸片段。比较并分析了该片段的钦洲湾、长沙湾、镇海湾和珠江口共105个近江牡蛎个体的核苷酸序列多态性,共检测到23个多态性核苷酸突变位点,包括16个转换位点和7个颠换位点,发现了1个核苷酸插入突变位点。4个群体可分为12种单倍型。结果表明：4个群体中广西钦洲湾群体遗传多样性最高,其次为长沙湾、珠江口群体,镇海湾群体最低。     

Processing of an apatite-mullite glass-ceramic and an hydroxyapatite/phosphate glass composite by selective laser sintering

The work presented details the results of an investigation into the feasibility of using Selective Laser Sintering (SLS) to directly produce customised bioceramic implants. The materials used were bioactive in nature and included a glass-ceramic and a combination of hydroxyapatite and phosphate glass. The glass-ceramic was selected from the range of apatite-mullite materials in the SiO2.Al2O3.CaO.CaF2.P2O5 series, due to their potentially suitable biological and mechanical properties. The hydroxyapatite and phosphate glass combination was chosen to allow an alternative production approach to be investigated. The viability of using both these materials with the SLS process was assessed and the process route and resulting material properties characterised using a variety of techniques including Differential Thermal Analysis (DTA), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM).The results obtained indicate that it was possible to produce multiple layer components from both materials using the SLS process. The glass-ceramic materials could only be processed at very low scan speeds and powers, yielding relatively brittle components. It was though possible to produce parts from the hydroxyapatite and phosphate glass combination across a much wider range of parameters, producing parts which had a greater potential for possible implant production.     

The RIM-process — A highly developed technology

To produce high-quality polyurethane-reaction injection moulding (PUR-RIM) of the sort used in automotive exterior applications, the essential requirements are high-performance machinery and equipment plus a thorough understanding of all the processing parameters. Successful production of blemish free articles at fast cycles, ready for painting and requiring no post-treatment is only possible if the interconnected chemical and technical processing sequences all function in perfect harmony. Working towards this goal, several teams of chemists, processing engineers and manufacturers have been co-operating on intensive programmes of research and development, and today it can justifiably be claimed that the RIM process is remarkably mature for such a young technology. A determined effort is now required to incorporate the latest findings into the design of new machinery and to modify existing machinery accordingly.

In this paper, a detailed discussion is presented of the two most important processing parameters (temperature and pressure) and the various factors which depend on them, and the need for accurate control of these parameters during the manufacturing process is stressed. Details are also given of a production line complete with tooling designed specifically for the process. Together with an appropriate system of measuring, monitoring and recording the processing parameters, this is an essential prerequisite for cost-efficient production.     

Out-of-autoclave cure cycle study of a resin film infusion process using in situ process monitoring

Liquid resin infusion (LRI) of textile tailored reinforcements (TRs) is increasingly applied in new processing technologies for manufacturing carbon fibre composites. This work presents a cure cycle study of an out-of-autoclave toughened resin film infusion (RFI) process as part of the examination of an alternative manufacturing process for composites. To successfully produce laminates using resin film infusion in combination with a fast-curing process, the flow behaviour of the selected resin material under changed processing conditions was investigated. The effect of processing parameters, specifically heating rates and dwell times, on resin viscosity and laminate infiltration was evaluated through experimental work and supported by in situ process monitoring. A DC-resistance sensor system was applied to track the change in resin viscosity during cure. Results showed that cure cycles with a relatively short dwell time and higher heating rate compared to an autoclave cure led to enhanced flow properties of the toughened resin system. High quality laminates, comparable to autoclave panels, were manufactured with vacuum pressure only by modifying the original vacuum bagging arrangement.     

On adsorption of aluminium and methyl groups on silica for TMA/H<Subscript>2</Subscript>O process in atomic layer deposition of aluminium oxide nano layers

A detailed chemisorption mechanism is proposed for the atomic layer deposition (ALD) of aluminium oxide nano layers using trimethyl aluminum (TMA) and water as precursors. Six possible chemisorption mechanisms, complete ligand exchange, partial ligand exchange, simple dissociation, complete dissociation via ligand exchange, complete dissociation and association, are proposed and related parameters like ligand to metal ratio (L/M), concentrations of metal atoms and methyl groups adsorbed are calculated and compared against reported values. The maximum number of methyl groups that can get attached on the surface is calculated in a different way which yields a more realistic value of 6·25 per nm² substrate area. The dependence of the number of metal atoms adsorbed on OH concentration is explained clearly. It is proposed that a combination of complete ligand exchange and complete dissociation is the most probable chemisorption mechanism taking place at various OH concentrations.     

Optical asymmetric cryptosystem based on photon counting and phase-truncated Fresnel transforms

We propose a novel optical asymmetric cryptosystem combining the photon counting imaging with phase-truncated Fresnel transform, which can be used for complete information retrieval and authentication verification. The proposed combination overcomes the weakness of photon counting-based double random phase-encoding scheme. For retrieval of original image for authentication, the reverse process of phase truncation approach is followed and a nonlinear correlation filter is used. The complete information retrieval and authentication verification are possible provided sufficient number of photons is available. To check the robustness of the proposed scheme, attack analysis has been carried out. The simulation results are presented to demonstrate the proposed idea.     

Optimal process plan selection in networked based manufacturing using game-theoretic approach

This paper proposes a scheme for generating optimal process plans for multi jobs in a networked based manufacturing system. Networked manufacturing offers several advantages in the current competitive atmosphere such as reducing short manufacturing cycle time and maintaining the production flexibility, thereby achieving several feasible process plans. An N-person non-co-operative game with complete information is proposed and a mathematical model has been developed to generate the payoff functions. To be part of a game, we divided the game into two sub-games such as games to address sub-game (GASG) and games to solve sub-game (GSSG) which try to interact with each other and achieve the Nash equilibrium (NE). Consequently, a hybrid dynamic-DNA (HD-DNA) based evolutionary algorithm approach has been developed for more effective solutions of the game and also for finding the perfect NE points. The objective of this game is to generate the optimal process plans to minimise the makespan. Finally, three cases having different job complexities are presented to demonstrate the feasibility of the approach. The proposed algorithm is validated and results are analysed to benefit the manufacturer.     

纯化—反应—浓缩—结晶—分级工序合一的液膜工艺(Ⅰ)

首次提出了一个对某些化工过程可将五个工序合而为一的液膜工艺,对合并的可能性进行了理论分析和六个可行性的试验,对从中选出的一个在合并难度上具有代表性的仲钨酸铵结晶的生产所作全面性的试验,技术上和经济上结果都十分成功,在此基础上,提出了用此工艺日产100公斤APT的技术方案和经济预测。     

Direct observation of frictional seizure of mild steel sliding on aluminum by X-ray imaging Part II Mechanism

Observation of frictional contacts has always been a problem for long as the contact is normally hidden. In this work, we have used an X-ray microscope for in-situ observation of frictional seizure, wear and interfacial features during the testing of mild steel specimens sliding against Al 6061 disk. This technique enables the observation of interfacial features of the hidden contact. Seizure tests were conducted at different sliding speeds of 2, 4 and 5 m/s. The images obtained during the tests indicated that the wear process was a combination of random transfer events and cyclic process of a close contact followed by a partial separation of the sliding surfaces. Wear was concentrated over a certain specific area during the initial part of the test but later the contact developed into a conformal contact following a lumpy transfer of material. The mechanisms of seizure and wear were affected by the sliding speed. At a sliding speed of 4 and 5 m/s, the transfer and bonding of material was not directly caused by nascent surface contact but due to contact of rolled and compacted wear debris with the nascent surfaces. Whereas at lower sliding speed (2 m/s) the transfer and bonding of deposits occurred due to direct contact of nascent sliding surfaces.     

Experimental and finite element investigation of semi-constrained groove pressing process

In this research the semi-constrained groove pressing (SCGP) process as a severe plastic deformation (SPD) method was applied on commercially pure aluminum plates. According to the principle of SCGP, a material is subjected to repetitive shear deformation by utilizing asymmetrically grooved dies and flat dies which are constrained by a channel rather than a container used in the CGP process. Each complete groove pressing pass consists of four pressing operation steps. Considering the geometry of the die, in each complete pass, a large amount of strain is induced into the specimen. In the present research the effects of the deformation passes on the mechanical properties of the specimens were tested by microhardness tests and tensile tests. In addition, in order to investigate the material flow along the grooves in the SCGP process, the finite element simulations were carried out in three different conditions (3D, 2D plane strain and 2D plane stress) for the first time. Results show that the flow stress of the material and its hardness are affected by the number of passes. Analysis of force diagrams showed that the real state of the SCGP process is a combination of plane stress and plane strain conditions.     

Complete Analysis of STJ Detector Performance via Absorption of Phonon Pulses

For the first time a complete analysis of the tunnel and loss parameters of superconducting tunnel junction photon detectors has been made solely by the use of nanosecond phonon pulse excitation. Previously only a partial characterization, requiring supplementary information from photo-excitation measurements, was possible. The present results have been achieved by a more realistic model for the energy spectrum of the phonon pulses and greatly improved (nanosecond) time resolution of the detected signal. The value determined for the tunnel rate is in good agreement with calculations based on the device layer structure. It is believed that the relatively high values of loss time obtained are the result of trap-enhanced recombination due to the high quasiparticle densities attained in the experiments.      

Design of flexible manpower line walk cycles for a fixed number of operators

Flexible manpower lines (FMLs) are a form of flow process line in which operators are allocated ‘walk cycles’, i.e. a repetitive sequence in which to load and unload machine tools. The effective design of such lines is normally achieved with the expectation that operators without full walk cycles, i.e. those that do not require a full Takt time to accomplish, can complete their walk cycles at an adjoining FML. However, an alternative FML design strategy is possible in cases where no adjoining FML exists or it is not possible for operators to move between work areas. This strategy involves determining the minimum Takt time and the associated operator walk cycles at which the FML can operate under a fixed number of operators. To solve this type of problem, a genetic algorithm that make use of a novel crossover operator has been developed that can design FMLs. The genetic algorithm is capable of generating, for a specific Takt time and fixed number of operators, FMLs with high-quality, near-optimal operator walk cycles. Solutions for the fixed manpower case were then identified by performing multiple genetic algorithm runs to find the best walk cycles at various Takt times.     

Deriving control parameter settings from process models to control capsule fillers integrated into continuous manufacturing

The aim of this work was to investigate the mean fill weight control of a continuous capsule-filling process, whether it is possible to derive controller settings from an appendant process model. To that end, a system composed out of fully automated capsule filler and an online gravimetric scale was used to control the filled weight. This setup allows to examine challenges associated with continuous manufacturing processes, such as variations in the amount of active pharmaceutical ingredient (API) in the mixture due to fluctuations of the feeders or due to altered excipient batch qualities. Two types of controllers were investigated: a feedback control and a combination of feedback and feedforward control. Although both of those are common in the industry, determining the optimal parameter settings remains an issue. In this study, we developed a method to derive the control parameters based on process models in order to obtain optimal control for each filled product. Determined via rapid automated process development (RAPD), this method is an effective and fast way of determining control parameters. The method allowed us to optimize the weight control for three pharmaceutical excipients. By conducting experiments, we verified the feasibility of the proposed method and studied the dynamics of the controlled system. Our work provides important basic data on how capsule filler can be implemented into continuous manufacturing systems.     

Evaluation of static and fatigue strength of long fiber GRP composite material considering moisture effects

The paper presents results of a partial experimental programme of evaluation of static mechanical and fatigue properties of long glass-fiber reinforced polymer composite material with a multiaxial orientation of glass fibers to be used for a manufacture of the flywheel hub disc, the main component of the storage unit accumulating kinetic energy of a vehicle during braking for further use during acceleration. Though humidity is not supposed to be an issue in operation of the unit, an experimental programme evaluating the material static strength and durability under combination of static load with vibration component was carried out to complete the overall general material characterisation. Study of an effect of absorbed moisture was a part of the experimental work. Water absorption was a long-term process, without saturation even after several months. Degradation of strength and fatigue properties due to the absorbed distilled water was confirmed for this material. The material sensitivity on vibration component of the load, even with quite low amplitude of 10% of the static load was ascertained. Damage accumulation and continuous stiffness reduction during fatigue tests, which rate was connected with final durability, was an important phenomenon.     

Optimal process parameter determination for computer‐aided manufacturing

Producing high‐quality products at low cost is one of the key factors to survival for manufacturing sectors in today's intense global competition environment. One way to gain competitiveness is to integrate product design and process planning into one activity. This study attempts to determine optimal process parameters for a manufacturing process under given design parameters. The process parameters to be determined in this study include process means and process tolerances for particular manufacturing process sequences. The problem is formulated in constrained non‐linear optimization, considering both quality‐ and manufacturing‐related costs. The proposed application evaluates alternative product designs and process sequences so that the best associated process parameters can be determined during the early stages of design and planning. This makes the link between CAD and CAM systems more useful and effective. As a result, optimal integration of product design and process planning with minimal production costs and maximal product quality is possible. Copyright © 1999 John Wiley & Sons, Ltd.