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P.Y.L. Tu R. Yam P. Tse A.O. Sun 《The International Journal of Advanced Manufacturing Technology》2001,17(9):692-703
Maintenance costs in advanced manufacturing companies, e.g. electronics manufacturing companies, have been steadily increasing
as the companies upgrade their production facilities. Maintenance costs are normally a considerable portion of the product
cost. To maintain a competitive place in the market, it is critical for an advanced manufacturing company to have a sound
maintenance management system, which can control its maintenance costs at the lowest level and maintain its overall equipment
effectiveness at the highest level. This paper reports on an integrated maintenance management system, which has been developed
and implemented in an advanced electronics manufacturing company in Hong Kong. The methods and principles of the system are
discussed in sections on maintenance performance auditing, cost recording and tracing, reliability centred maintenance planning
and control, condition monitoring and on-line feedback control, and integrated maintenance planning and control. 相似文献
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J. Beg M. S. Shunmugam 《The International Journal of Advanced Manufacturing Technology》2002,19(12):905-916
Coordinate measuring machines (CMMs) have been widely accepted and are increasingly used for carrying out inspections. With
the increase in complex designs and tighter tolerances, the inspection process involving a CMM has become critical and there
is a need to plan it effectively. In the present work, an object oriented planner for the inspection of prismatic parts (OOPIPP)
has been developed. It incorporates interactive feature recognition and carries out all the essential steps of inspection
planning, that is, selection of the most stable part orientation, arriving at number and distribution of inspection points,
feature accessibility analysis, sequencing of probe orientations, removal of duplicate faces, and, finally, sequencing of
faces. Various relationships between different entities of the system and distinct features of OOM have been used to develop
the algorithms of different modules. Fuzzy logic for decision making has also been applied and a suitable method of combining
fuzzy sets has been used for the selection of part orientation and for sequencing probe orientations. 相似文献
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分析比较FMS的计算机监控系统不同结构形式的特点,重点研究分布式控制系统在FMS中的应用及存在的主要问题,提出引入“竞争机制”的方法来改善分布式系统整体性能的思想,并举例简要介绍有关竞争规划及算法的建立。 相似文献
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A Study on Electrochemical Micromachining for Fabrication of Microgrooves in an Air-Lubricated Hydrodynamic Bearing 总被引:1,自引:1,他引:1
Y.-H. Moon E.-S. Lee J.-W. Park 《The International Journal of Advanced Manufacturing Technology》2002,20(10):720-726
A specially built electrochemical micromachining/pulsed electrochemical micromachining (EMM/PECM) cell, a electrode tool filled
with non-conducting material, a electrolyte flow control system and a small and stable gap control unit, are developed to
achieve accurate dimensions for spindle recesses. Two electrolytes, aqueous sodium nitrate and aqueous sodium chloride are
applied in this study. The former electrolyte has better machinability than the latter because of its ability to change appropriately
to the transpassive state without forming pits on the surface of the workpiece. It is easier to control the machining depth
precisely by micrometer with pulse current than direct current. This paper also presents an identification method for the
machining depth by the in-process analysis of the machining current and interelectrode gap size. The interelectrode gap characteristics,
including pulse current, effective volumetric electrochemical equivalent and electrolyte conductivity variations, are analysed,
based on the model and experiments.
ID="A1"Correspondance and offprint requests to: E.-S. Lee, Department of Mechanical Engineering, Inha University, 253, Yonghyun-Dong, Nam-Gu, Incheon, 402–751, Korea. E-mail:
leees@inha.ac.kr 相似文献
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Dual Material Rapid Prototyping Techniques for the Development of Biomedical Devices. Part 1: Space Creation 总被引:1,自引:0,他引:1
C. L. Liew K. F. Leong C. K. Chua Z. Du 《The International Journal of Advanced Manufacturing Technology》2001,18(10):717-723
Polymeric drug delivery devices play an important role in drug administration. However, the current polymeric drug delivery
device fabrication methods lack precision. This impairs the quality of the devices, resulting in a decrease in the efficiency
and effectiveness of drug delivery. The concept of building parts layer by layer out of powdered raw materials makes selective
laser sintering (SLS) a suitable process for fabricating polymeric matrix drug delivery devices. The current SLS process is
not capable of processing two or more materials separately. This work explores the possibilities of SLS per-forming a dual
material operation by developing two process models. These two processes can then be integrated to form a dual or expanded
multimaterial fabrication technique and act as a foundation for future work in multimaterial applications such as polymeric
drug delivery device fabrication. Accord-ingly, two papers are presented. In this paper, Part 1, the focus is on the first
process, which is a "space" creation technique in which a "space" is created by varying the density of a first representative
material using heat during sintering. Three methods – one based on a vacuum and a place method, and the other two based on
two variations of a laser compacting method – were tested. Results have shown that by varying the laser power during sintering,
it is possible to create channels in which a second material can be deposited. 相似文献
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H.264/AVC码率控制中初始量化参数的估计 总被引:1,自引:0,他引:1
由于H.264/AVC采用的码率控制模型忽略了视频特性对初始帧量化参数(Initial Quantization Parameter,QP0)选择的影响,本文提出了一种新的基于视频特性的QP0估计算法来提高H.264/AVC的码率控制精度。首先,分析影响QP0的视频特性,包括每像素比特数(bpp)、视频序列的复杂度和图像组(GOP)长度;然后,通过大量的测试仿真建立了QP0与bpp和视频序列复杂度之间的函数关系;最后,结合GOP长度对QP0的影响,修正了QP0模型。实验结果表明:相比JM12.2中的算法,提出的算法使四分之一通用中间格式(QCIF)和通用中间格式序列重建帧的平均峰值信噪比(PSNR)分别提高了0.185 dB和0.144 dB;码率控制误差的控制幅度分别提高了37.3%和11.2%;序列中每帧图像间的质量波动均降低了约50%。该方法在提高重建帧质量的同时,大幅度降低了码率控制误差,有效地抑制了序列间每帧图像的质量波动,获得了更优质、平稳的编码视频流,并能很好地适应不同特性的视频序列。 相似文献
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C. L. Liew K. F. Leong C. K. Chua Z. Du 《The International Journal of Advanced Manufacturing Technology》2002,19(9):679-687
Polymeric drug delivery devices play an important role in drug administration. However, the current polymeric drug delivery
device fabrication methods lack precision. This impairs the quality of the devices, resulting in a decrease in the efficiency
and effectiveness of drug delivery. The concept of building parts layer by layer out of powdered raw materials makes selective
laser sintering (SLS) a suitable process for fabricating polymeric matrix drug delivery devices. The current SLS process is
not capable of processing two or more materials separately. This work explores the possibilities of using SLS to perform a
dual material operation by developing two process models. The two processes can then be integrated to form a dual or multimaterial
fabrication technique and act as a foundation for future work in multimaterial applications such as polymeric drug delivery
device fabrication. Accordingly, two papers are presented.
In this paper, Part 2, the emphasis is on a secondary powder deposition method, which is an electrostatic technique based
on electrography. Developed toner on the photoconductor is scraped off using mechanical shearing and is deposited using an
electrostatic force by electroplating. Results have shown that by reducing the distance between the photoconductor and surface
of deposition, the resolution of the printout can be refined. Other important factors include the efficiency of powder removal
from the photoconductor, printing speed, and the traversing speed during deposition. 相似文献
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针对自动化生产设备不但需要自动控制而且还需要对设备运行中的数据进行存储、分析与处理的问题,将计算机软件技术应用到设备的自动控制技术中。通过分析数据的采集、传输、转换及生成之间的关系,提出了利用可编程控制器(PLC)进行自动化编程、利用人机界面进行操作画面设计、利用U盘完成数据的传送、利用计算机软件进行数据处理的综合方法;为验证该技术的先进性,在设备运行过程中对数据管理、报表生成、历史曲线图和加工参数等进行了评测。研究结果表明,在实际生产过程中,该技术能可靠地代替工业控制计算机来进行数据处理,具有一定的市场应用前景。 相似文献
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S. Lee M. Müller R. Heeb S. Zürcher S. Tosatti M. Heinrich F. Amstad S. Pechmann N.D. Spencer 《Tribology Letters》2006,24(3):217-223
We report on the self-healing behavior of a polyelectrolyte-based aqueous lubricant additive, poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), during aqueous lubrication of an oxide-based tribosystem. Combined pin-on-disk tribometry and fluorescence microscopy experiments have shown that stable lubricating performance was enabled by means of rapid healing of the worn tribopair surface by polymers dissolved in the adjoining bulk lubricant. This rapid ‘self-healing’ of PLL-g-PEG is attributed to electrostatic interactions between the polycationic poly(l-lysine) (PLL) backbone of the polymer and negatively charged oxide surface. In contrast, a similar healing effect was not readily achievable in the case of methoxy-poly(ethylene glycol)-trimethylsilylether (Sil-PEG), a lubricant additive that is covalently bonded to the surface prior to tribological stress. 相似文献
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The gasifier plays a key role in the operation of the whole IGCC power plant. It is a typical multivariable control system with strict constraints on the inputs and outputs which makes it very difficult to control. This paper presents a partially decentralized controller design method based on the stabilizer idea. The method only requires identifying some closed-loop transfer functions and solving an H∞ optimization problem. The final partially decentralized controller is easy to implement and test in practice. Two partially decentralized controllers are designed for the ALSTOM gasifier benchmark problem, and simulation results show that they both meet the design specifications. 相似文献
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In this paper we propose a new approach to on-line Takagi-Sugeno fuzzy model identification. It combines a recursive fuzzy c-means algorithm and recursive least squares. First the method is derived and than it is tested and compared on a benchmark problem of the Mackey-Glass time series with other established on-line identification methods. We showed that the developed algorithm gives a comparable degree of accuracy to other algorithms. The proposed algorithm can be used in a number of fields, including adaptive nonlinear control, model predictive control, fault detection, diagnostics and robotics. An example of identification based on a real data of the waste-water treatment process is also presented. 相似文献