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ABSTRACT: Geometry complexity and high-precision requirement have imposed a lot of challenges for the design, manufacturing, and measurement of ultra-precision freeform surfaces with submicrometer form accuracy and surface finish in nanometer range. Successful manufacturing of ultra-precision freeform surface not only relies on the high precision of machine tools, but also largely depends on comprehensive consideration of advanced optics design, modeling, and optimization of the machining process, freeform surface measurement and characterization. Currently, there is still a lack of an integrated system to fill the gap between those different important stages for producing a complete optics part. This paper presents the theoretical basis for the establishment of an integrated platform for the design, fabrication, and measurement of ultra-precision freeform surfaces. The platform mainly consists of four key modules, which are optics design module, data exchange module, machining process simulation and optimization module and freeform measurement and evaluation module. A series of experiments have been conducted to evaluate the performance of the platform and its capability is realized through a trial implementation in the design, fabrication and measurement of an F-theta lens. The predicted values by the models in the system are found to agree well with the experimental results, and the freeform characterization results are also validated by the experiments. These show that the proposed integrated platform not only helps to shorten the cycle time for the development of freeform components but also provides an important means for optimizing the surface quality in the ultra-precision machining of freeform surfaces. With this system, optimal machining parameters, the best cutting strategy, and the optimization of the surface quality can be obtained without the need for conducting time-consuming and expensive cutting tests. This contributes to the advancement of the manufacturing -
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IEEE Transactions on Electronics Packaging Manufacturing 11/2010; · 1.16 Impact Factor
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ABSTRACT: Ultra-precision freeform surfaces are complex surfaces that possess non-rotational symmetry and are widely used in advanced optics applications. Due to the geometrical complexity of optical freeform surfaces, there is, as yet, a lack of generalized surface characterization methods which measure various types of ultra-precision freeform surfaces with sub-micrometer form accuracy and surface finish in the nanometer range. To make good this deficiency, a generalized approach for the measurement and characterization of ultra-precision freeform surfaces, named the intrinsic surface feature-based method (ISFM), is presented in this paper. The ISFM makes use of intrinsic surface properties (e.g. curvatures, normal vectors, torsion and intrinsic frames) to conduct data matching or uses some algorithms to search for correspondences such as correlation functions. The method is experimentally verified through a series of measurement experiments. The results show that the proposed ISFM is capable of addressing the deficiencies and limitations of traditional freeform surface characterization methods which are susceptible to outliers and to uncertainty due to the geometry of the freeform surfaces. ISFM is a generalized methodology which is not dependent on the type of freeform surface being characterized.
Measurement Science and Technology 10/2010; 21(11):115109. · 1.49 Impact Factor
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ABSTRACT: Purpose – The purpose of this paper is to focus on the design of a counterfeit network analyzer (CNA) for aggregating all the problematic product flows in order to discover any counterfeit distribution source, and to control the spread of counterfeit goods. The analyzer leverages radio frequency identification (RFID) information stored within the electronic product code (EPC) network. Design/methodology/approach – The system architecture of the proposed CNA is first discussed. A case study of the system application in a Hong Kong pharmaceutical manufacturing company then presents the adoption process and the challenges encountered in such technologies. Findings – Compared with traditional approaches, the results show that the proposed RFID solution is reliable and is capable of discovering counterfeit distributions, as well as reducing the detection costs by means of higher product movement visibility within the supply chain. Practical implications – A prototype system has been constructed and trial implemented in a pharmaceutical manufacturing company. It proved to be of benefit to the manufacturer who is able to deter product counterfeiting effectively and visualize real-time supply chain data automatically. Originality/value – The proposed CNA is designed to overcome issues of information invisibility, which is considered a huge cost lost in the identification of counterfeit products, loss of sales and reputation associated with the counterfeiting, and ineffective product authentication in the manufacturing industry. This paper contributes to the RFID research in the counterfeiting area by studying the feasibility and practicality of shifting the focus of product identification from the traditional package redesign solutions to the visualization of the movement of the product (i.e. product supply chain) via the use of RFID and EPC. Furthermore, a pharmaceutical manufacturing site provided a case study for discussing the advantages, critical issues for implementation of the RFID system, and lessons learned.
Industrial Management & Data Systems 08/2010; 110(7):1018-1037. · 1.47 Impact Factor
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ABSTRACT: Nowadays, freeform optical components are being used in various applications such as photonics, telecommunications, automotive lighting, etc. However, there is still lack of international standards for characterizing the form error of a freeform surface due to its geometrical complexity. At present, there are generally two main approaches to inspecting the form deviation, the fitting and matching approaches, respectively. However, the fitting approach is inevitably affected by the 'error-eroded' measured data while the matching approach is susceptible to the 'swelling/squeezing' data caused by the measurement instrument. This paper presents a hybrid fitting and matching method (HFMM) which takes the advantages and addresses the shortcomings of both fitting and matching approaches. The HFMM has been verified by a series of measurement experiments. A sample of the freeform surface was measured and characterized by different techniques and the results were compared. It is found that the proposed method performs better than the fitting or matching approach. The successful development of the hybrid fitting and matching method significantly contributes to a potential solution for the standardization of the freeform surface characterization method.
Measurement Science and Technology 09/2009; 20(10):105103. · 1.49 Impact Factor
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ABSTRACT: The use of radio frequency identification (RFID) in manufacturing process automation is becoming increasingly popular in various industries. However, the integration of RFID with various manufacturing systems is still a challenge. This paper presents the development of a framework for an RFID-based manufacturing process automation system (MPAS) for use in manufacturing industries. The MPAS is characterised by its ability to capture and harness real-time production and process data of semi-finished products and components during the manufacturing and assembly processes. It supports rapid logistics decision-making for the re-allocation of production resources and rectification of bottleneck problems to meet tight delivery schedules. A prototype system has been built and the potential benefit of the system has been realised through a series of implementations in selected reference sites.
International Journal of Logistics Economics and Globalisation 01/2009; 2(1):1-22.
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ABSTRACT: Flat optical freeform surfaces usually possess non-rotational symmetry with a small curvature and lack of strong features for surface alignment. Due to the lack of strong features and small curvature, it is difficult to align the design and measured surfaces for characterizing the surface quality of flat optical freeform surfaces with sub-micrometre form accuracy. The traditional least squares method (LSM) generally produces large errors as there is a lack of strong features as reference for the alignment of the design and measured surfaces. This paper proposes a novel and practical method named the coupled reference data method (CRDM) to evaluate flat optical freeform surfaces with high efficiency and precision in the nanometre scale. The method couples reference data to the workpiece of the freeform surface designed model and the concerning reference features are machined together with the workpiece. By aligning the reference data, the proposed CRDM carries out fast surface matching. This makes good preparation for the next matching optimization which is conducted by the least-squares and minimax zone method. After the precise surface matching, the flat optical freeform surface can be evaluated by 3D form error topography and parameters. As compared with a traditional freeform measurement method such as LSM, it is interesting to note that the accuracy and the stability of the measurement can be significantly enhanced by the CRDM.
Measurement Science and Technology 06/2007; 18(7):2252. · 1.49 Impact Factor
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ABSTRACT: Managing knowledge of plant maintenance in a power utility company is vital to the provision of a safe and reliable electricity supply to two million domestic and commercial customers. The business is built on a lot of expertise, techniques and experience of all of its employees from engineering, maintenance, safety and environmental control, to quality assurance. Knowledge auditing is usually carried out as the first critical step in the implementation of any Knowledge Management programmes in power utility companies. Although various knowledge auditing approaches have been proposed by some researchers and practitioners, there is a lack of a systematic approach in the way it is conducted, and the audit practice varies with different industries and companies. This paper presents a systematic knowledge audit approach, which has been successfully trial-implemented in a power plant.
Journal of Information & Knowledge Management (JIKM). 01/2007; 06(04):231-239.
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ABSTRACT: An investigation of the characteristics of microcutting forces in diamond turning of crystalline materials is presented. The characteristics of the cutting forces were extracted and analyzed using statistical and spectrum analysis methods. A series of cutting experiments were done on a copper alloy and copper single crystals with different crystallographic orientations. Experimental results indicate that there exists a dominant frequency component and a periodicity of fluctuation of the cutting forces per workpiece revolution in the diamond turning of a single crystal material. The periodicity is closely related to the crystallographic orientation of the material being cut. As the depth of cut increases, the influence of crystallographic orientation of the single-crystal materials on microcutting forces is found to be more pronounced. Moreover, the cutting force ratio between the mean thrust force and the mean cutting force is found to vary with the depth of cut, and a large ratio was observed at a small depth of cut. These findings help to explain quantitatively the periodic fluctuations of microcutting forces (and hence the materials-induced vibration) in ultraprecision diamond turning, which are not encountered in conventional machining.
Materials and Manufacturing Processes 08/2006; 16(2)(177–193 (2001)):177-193. · 1.06 Impact Factor
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ABSTRACT: Purpose – Effective service logistics can lower the cost and increase service value by improving customer satisfaction and loyalty. However, the conventional ways of the service logistics are information driven instead of knowledge-driven which are insufficient to meet the current needs. The purpose of this paper is to present a knowledge-based service automation system (KBSAS) to enhance the competitiveness for manufacturing enterprises in service logistics. Design/methodology/approach – The KBSAS incorporates various artificial intelligence technologies such as case-based reasoning which is used for achieving four perspectives of knowledge acquisition, service logistics, service automation and performance measurement, respectively. Findings – A prototype customer service portal has been built based on the KBSAS and implemented successfully in a semi-conductor equipment manufacturing company. It is verified that the KBSAS provides high quality customer services with fast and efficient customer responses. It also allows the company to capture the valuable experience and tacit knowledge of the staff in performing customer and field services. Practical implications – The KBSAS yields a number of advantages over conventional service logistics which include streamlining the service logistics process; performance measurement; reduction of paper work; the provision of 24 hours worldwide automatic customer service supported by the verified knowledge base established in the date time operations as well as the driving for continuous improvement of customer service quality. Originality/value – The paper presents the development and successful implementation of a KBSAS which allows for the capture of the valuable experience and tacit knowledge of the staff in performing customer and field services.
Journal of Manufacturing Technology Management 07/2006; 17(6):750-771.
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ABSTRACT: Ultra-precision freeform surfaces are complex surfaces that possess non-rotational symmetry and are widely used in advanced optics applications. However, there is a lack of a surface characterization method that measures the form accuracy of the ultra-precision freeform surfaces with micrometre to sub-micrometre form accuracy. Due to the high precision requirement of the ultra-precision freeform surfaces, this inevitably involves the outliers in the measured data that would significantly affect the accuracy and the performance of the form characterization method. Although some research work has been found in the development of the form characterization method, most workers have not considered the influence of outliers. It is vital to incorporate robust estimation in the surface characterization method for catering for the influence of outliers. In this paper, a robust form characterization method (RFCM) is presented to characterize the form accuracy of the ultra-precision freeform surfaces. A series of computer simulation and experimental analyses were undertaken to verify the RFCM. The theoretical results agree well with the simulation and experimental results.
Measurement Science and Technology 01/2006; 17(3):488. · 1.49 Impact Factor
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ABSTRACT: Many organisations have their own methods for survey activities. It is difficult to design questionnaires, which is considered to be a time-consuming processes for conducting a survey. Due to ineffective sharing and the retention of knowledge, organisations spend much time and effort to study past cases and previous know-how for conducting the survey. As a result, this paper presents a knowledge-based system approach for the customisation and the management of E-survey activities. A prototype knowledge-based survey system is built and the capability of the system is demonstrated through a successful trial implementation in a manufacturing enterprise.
Journal of Information & Knowledge Management (JIKM). 01/2006; 05(01):81-96.
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ABSTRACT: Ultra-precision freeform surfaces are widely used in many advanced optics applications which demand for having surface roughness down to nanometer range. Although a lot of research work has been reported on the study of surface generation, reconstruction and surface characterization such as MOTIF and fractal analysis, most of them are focused on axial symmetric surfaces such as aspheric surfaces. Relative little research work has been found in the characterization of surface roughness in ultra-precision freeform surfaces. In this paper, a novel Robust Gaussian Filtering (RGF) method is proposed for the characterisation of surface roughness for ultra-precision freeform surfaces with known mathematic model or a clould of discrete points. A series of computer simulation and measurement experiments were conducted to verify the capability of the proposed method. The experimental results were found to agree well with the theoretical results.
Journal of Physics Conference Series 09/2005; 13(1):32.
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ABSTRACT: In order to stay competitive with international markets, companies must deliver new products with higher quality in a shorter time with a broader variety of versions at minimum costs. Virtual manufacturing (VM) is quickly becoming an interesting strategy for product development. Primarily aimed at reducing the lead times to market and costs associated with new product development, VM offers a test-bed for the time-consuming and expensive physical experimentation. In this paper, several key issues for developing a virtual turning test-bed by using virtual manufacturing technology are discussed, i.e., representation of a workpiece with the capability of transferring error data used for machining accuracy prediction and reflecting the machining accuracy, representation of the swept volume of a tool for simulating turning process with high efficiency. The construction of surface topography, a basic model for machining accuracy prediction is also highlighted. The representations and relevant algorithms discussed in this paper are implemented in a virtual turning test-bed. A virtual machining and inspection system (VMIS) for ultra-precision diamond turning is presented and experiments are carried out to demonstrate it.
International Journal of Advanced Manufacturing Technology 04/2005; 25(9):857-866. · 1.10 Impact Factor
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ABSTRACT: Knowledge management (KM) attracts more and more attention nowadays in either research or practice. Organisations often spend a lot of time and money to launch strategic KM initiatives without first assessing whether or not their culture is ready for the implementation of such initiatives. If the culture is not ready for implementing the initiatives, the effort put will rarely produce significant long-term benefits. Instead, employees will perceive them as a waste of time, and participate less actively in the KM initiatives. In this paper, a KM culture assessment tool (KMCAT) is purposely developed for assessing the organisational culture so as to ensure the success of implementation of KM initiatives. The KMCAT takes into account coherence, control, alliance and partnership, information and communication technology as well as innovation, which help an organisation to reveal culture profiles and hence provide directions for managing the culture. A case study of applying the KMCAT is undertaken in an aviation company and encouraging results are obtained.
Journal of Information & Knowledge Management (JIKM). 01/2005; 04(03):179-189.
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ABSTRACT: This paper presents an agent-oriented and knowledge-based system (AOKBS) for strategic e-procurement. The AOKBS has been designed to capture and leverage the knowledge of an enterprise to generate dynamic business rules by which an effective procurement strategy can be generated based on enterprise needs and the analysis of relevant market conditions. The performance and practices of the suppliers can also be evaluated and captured continuously, respectively, by the AOKBS. Artificial intelligence technologies such as case-based reasoning and agent technology are incorporated for decision analysis. A prototype e-procurement system has been built and implemented successfully with a multinational manufacturer.
Expert Systems 01/2004; 21(1):11 - 21. · 0.68 Impact Factor
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International Journal of Advanced Manufacturing Technology 01/2002; 19(4):245-252. · 1.10 Impact Factor
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ABSTRACT: The effect of material swelling on the surface roughness in ultraprecision diamond turning has been investigated. Experimental results from the power spectrum analysis indicate that the profile of the tool marks is distorted by the effect of swelling of the materials being cut. A good correlation exists between the surface roughness and the amount of swelling that has occurred in the machined layer. Radically different surface roughness profiles were obtained when machining aluminium and copper single crystals with the same cutting plane and tool shape. The difference in the machining behaviour could not be accounted for by elastic recovery alone but could be explained by considering the plastic deformation induced in the machined layer.
Materials Science and Technology 12/2000; 17(1):102-108. · 0.77 Impact Factor
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Materials and Manufacturing Processes 07/2000; 15(4):481-502. · 1.06 Impact Factor
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ABSTRACT: Ultra-precision machining has drawn much attention and the error compensation is an essential issue for improving the accuracy of the machining process. However, the analysis of kinematics errors on the surface generation in ultra-precision machining has received relatively little attention. Ultra-precision machine can be represented as a multi-body system. Based on the theory of multi-body system, a kinematics model of two-axis ultra-precision machining system has been developed in the present study. Hence, a software error compensation method is incorporated which is carried out by modifying the idea tool path in the NC program. The modified NC program takes into account the kinematics error factors and so the actual tool path generation can be compensated for the kinematics errors on the machining of the surface of the workpiece. To verify the theoretical kinematics model and the error compensation method, a series of machining experiments have been conducted and the experimental results indicate that better surface quality was achieved with the implementation of the proposed compensation method.
International Journal of Machine Tools and Manufacture 48:1408-1419. · 2.17 Impact Factor
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ABSTRACT: A lot of research work has been focused on the study of the surface generation mechanisms in order to predict the surface topography and provide the optimal machined parameters based on the experiential understanding of relationship of machined conditions and surface features. Although the formation of novel geometrical product specification (GPS) and verification framework system promotes the relevant research work to new characterization methods and draft of international standards, relative little research work was conducted on the application of surface characterization techniques to ultra-precision machining which is very important to evaluate the surface quality. In this paper, a novel robust Gaussian filtering method (RGF) is proposed and used to characterize the surface topography of ultra-precision machined surfaces. Cubic B-spline and M-estimation are used to make the method reliable and robust. Based on the property comparisons of classical weighting functions, a novel auto-developed robust weighting function (ADRF) is defined to improve the robustness of RGF. To verify the characterization feasibility of the proposed method, computer simulation is used and then the real ultra-precision machined surfaces are analyzed. The experimental results indicate that the RGF method cannot only separate the surface components effectively on the whole measured area and but also eliminates the influence of freak outliers.
Precision Engineering. 30(4):421-430.
