Development of a generalized theoretical model for the response of a phase/doppler measurement system to arbitrarily oriented fibers illuminated by gaussian beams

We present a generalized theoretical model for the response of the phase/Doppler (P/D) measurement system to light scattered by cylindrical fibers. This theoretical model is valid for arbitrary fiber diameters and refractive indices, for Gaussian incident beams, and it accounts for arbitrary fiber orientations, fiber positions, and effects that are due to the two-dimensional receivers. The generalized P/D computer model (GPDCM) is the extension of an earlier study by the authors, combining past P/D simulation methodology with recent developments in modeling light scattering by tilted cylindrical fibers. A fortran computer program that implements the GPDCM theoretical development was written and tested against known P/D results and physical expectations. To illustrate the capabilities of the GPDCM, we present computation results, comparing the effect of fiber tilt, fiber position, and receiver aperture on the performance of P/D systems configured in backscatter and sidescatter arrangements. Calculations show that the effects of fiber tilt and position are most pronounced in the backscatter P/D arrangement, resulting in broadening of the measured phase distribution. The calculated mean phase shifts, however, were found to be essentially independent of the above factors. Computational results also showed that the effect of fiber tilt and position on phase-distribution measurements can be reduced through proper choice of aperture shape and by imposition of threshold criteria on measurable signal characteristics such as the amplitude ratio and visibilities. The GPDCM provides a computational tool that will be valuable in the design, optimization, and evaluation of P/D fiber measurement systems.     

Design and implementation of a virtual information system for agile manufacturing

In the new and emerging agile manufacturing paradigm, where multiple firms cooperate under flexible virtual enterprise structures, there exists a great need for a mechanism to manage and control information flow among collaborating partners. In response to this pressing need, this paper addresses the design and implementation of an agile manufacturing information system integrating manufacturing databases dispersed at various partner sites. We propose a framework in which: (1) information is modeled in a hierarchical fashion using object-oriented methodology (OOM); (2) information transactions are specified by the workflow hierarchy consisting of partner workflows; (3) information flow between partners is controlled by a set of distributed workflow managers (WM) interacting with partner knowledge bases, which reflect partner specific information control rules on internal data exchange, as well as inter-partner mutual protocols for joint partner communications; (4) the prototype system is accomplished using the World Wide Web based on a client-server architecture. The overall approach and system provides within a dynamic environment, where virtual partnerships are synthesized in response to specific business initiatives, a dynamic and flexible mechanism to support partner information exchange and to keep the dispersed information consistent.     

Performance measurement for a manufacturing system based on quality,cost and time

Product quality, manufacturing cost and manufacturing time are three of the major concerns in a manufacturing system. This study proposes a product capability index to evaluate the quality of a multi-process product and addresses the relationship between process yield and the product capability index. In addition, this paper develops a time–cost index to assess manufacturing cost and manufacturing time. The quality index and time–cost index are simultaneously used to monitor product quality and manufacturing time on a quality and time–cost analysis chart. The quality and time–cost analysis chart, providing accurate information on the quality status and time–cost status for each process, helps to initiate, effectively and efficiently, quality improvement plans to elevate product quality and manufacturing time and manufacturing cost control for a manufacturing system.     

Scheduling a tempered glass manufacturing system: a three-stage hybrid flow shop model

Chinese tempered glass has entered a fast and stable growing era. To improve the productivity of tempered glass manufacturers, this paper investigates a scheduling problem in tempered glass production system, originated from a tempered glass manufacturer in China. This problem can be formulated as a three-stage hybrid flow shop (HFS). Single and batch processing machines coexist in this HFS. Besides, a limited buffer, between the first two stages, and machine eligibility requirement are also significant characteristics. To address this complicated scheduling problem, we first establish an integer programming model with the objective of minimising the makespan, i.e. the maximum completion time of jobs in the system. Due to the strong NP-hard nature of the problem, we then propose a constructive heuristic method, a genetic algorithm, as well as a simulated annealing algorithm, to solve practical large-scale problems. Computational results demonstrate the efficiency of the proposed approaches.     

Design of magneto-optical system for imaging of magnetic flux created during a conductor-superconductor phase transition

According to the Kibble-Zurek model, flux lines are spontaneously created during a fast conductor-superconductor phase transition. The model predicts both the spatial density and the correlations of the flux array. We present the design of a magneto-optical system with a projected single-flux-line resolution. Such a system can allow detailed measurements of the distribution of flux created spontaneously during a conductor-superconductor phase transition.     

Design of an automated guided vehicle-based material handling system for a flexible manufacturing system

Automated guided vehicle (AGV)-based material handling systems (MHSs), which are widely used in several flexible manufacturing system (FMS) installations, require a number of decisions to be made. These include the number of vehicles required, the track layout, traffic pattern along the AGV tracks, and solving traffic control problems. This paper addresses the key issues involved in the design and operation of AGV-based material handling systems for an FMS. The problems arising from multi-vehicle systems are analysed, and strategies for resolving them are examined using analytical and simulation models.     

Design of cascaded phase keys for a hierarchical security system

An image cryptosystem based on multiple phase-only masks is proposed. The proposed cryptosystem is a hierarchical security system that can use multiple phase keys to retrieve different amounts of data. In addition to the sequential order of the phase keys, the distance parameters among the phase keys are introduced to increase the system security. Even when an illegal user steals all the phase keys, the system cannot be broken without the correct sequential order and the distance parameters. However, the proposed system can verify the identities of the persons by the cascaded structure for the phase keys to generate different verification images. Simulation results are further demonstrated to verify the proposed method.     

Dose measurement for patients and physicians using a glass dosemeter during endovascular treatment for brain disease

It has been reported that exposure of patients and physicians to radiation from interventional radiological procedures cannot be disregarded. Direct measurement of patient exposure used to be difficult due to possible interference by the detector with the observation of X ray images. Recently, a dosemeter system consisting of small-sized glass chips and a reader which adopts pulsed UV laser stimulation has been developed. Owing to its small size, radiolucency and physical characteristics, direct monitoring of surface dose has become feasible. Dose measurement for patients and physicians during neurointervention was done using the photoluminescence glass dosemeter system. The dose-response of the dosemeter was almost linear over a broad dose range, but its energy dependency was rather high without a filter, the use of which is recommended by the manufacturer to compensate for energy dependency. Variation of sensitivity of about 20% was observed for effective energies of 45-60 keV which are used in neurointervention. In spite of this shortcoming, the photoluminescence glass dosemeter system was judged to be a convenient means for monitoring dose during neurointervention.     

Design and calibration of a noise measurement system

The setup principle and calibration method of a noise measurement system for frequencies from dc to 10 kHz are described. This system measures the current noise power spectral density of some device, and consists of a low-noise current preamplifier, a voltage preamplifier, and a dynamic signal analyzer which implements the fast Fourier transform (FFT). The noise aspects of the whole system can be modeled as a serial noise voltage generator and a parallel noise current generator at the input port, plus a system free of noise. The cross correlation of the two noise generators is an imaginary number because the system input stage is composed of some junction field effect transistors (JFET's). Via the thermal noise measurement of several resistors, we derive the magnitudes of the noise generators in addition to the input impedance and the total system gain. The imaginary cross correlation is obtained by the noise measurement of pure capacitance. With a well-calibrated procedure, we can measure the noise power down to 2×10^-27 A²/Hz. Two systems with different input stages were calibrated with the same procedure and the noise measurement results of the various resistance values with the two systems all agree well with theoretical values. One of these with an input stage which has a much smaller noise current generator shows great improvement in the noise measurement of the high-impedance device     

An investigation of amorphous phase separation, leachability and surface area of an ionomer glass system and a sodium-boro-silicate glass system

Glasses from a complex SiO₂-Al₂O₃-P₂O₅-CaO-CaF₂ glass series, known as 'ionomer glasses' were investigated. For comparison, a sodium-boro-silicate (s-b-s) glass system, which is known to undergo amorphous phase separation was also investigated. Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and BET surface area and pore distribution analysis were the principal analytical techniques used in this study. SEM analysis of the ionomer glass compositions revealed smooth spherical droplets of 2–15 nm while the background morphology appeared rough and speckled. A classic interconnected structure was observed for the s-b-s glass. EDX analysis of the s-b-s glass confirmed that the sodium-borate phase was removed by leaching with 0.3 M HNO₃, leaving behind a silica-rich structure. EDX analysis of ionomer glasses leached with 10% NaOH showed that the calcium and phosphate phases were being removed, although not to completion. For the base s-b-s glass a surface area of m 8² g^–1 was recorded. However, the base glass after extraction with 0.3 M HNO₃ of the sodium borate rich phase gave a BET surface area of 330 m² g^–1 indicating that it had already undergone phase separation on quenching from the melt, giving rise to a fine scale interconnected structure. The leached s-b-s glasses exhibited type 4 adsorption/desorption isotherms characteristic of mesoporous materials. Glasses which had been heat treated at 580°C for 4 h exhibited a surface area of 62 m² g^–1. This indicates that the as-quenched glass is already phase separated and that the phase separated microstructure is coarsening on heat treatment. A surface area of 4 m² g^–1 was measured for the base ionomer glasses. After leaching with 10% NaOH this value rose 10-fold with a maximum surface area of 44.1 m² g^–1 being recorded. The ionomer glasses also exhibited adsorption/desorption isotherms characteristic of mesoporous materials.     

Design of transmission-type phase holograms for a compact radar-cross-section measurement range at 650 GHz

A design formalism is presented for transmission-type phase holograms for use in a submillimeter-wave compact radar-cross-section (RCS) measurement range. The design method is based on rigorous electromagnetic grating theory combined with conventional hologram synthesis. Hologram structures consisting of a curved groove pattern on a 320 mmx280 mm Teflon plate are designed to transform an incoming spherical wave at 650 GHz into an output wave generating a 100 mm diameter planar field region (quiet zone) at a distance of 1 m. The reconstructed quiet-zone field is evaluated by a numerical simulation method. The uniformity of the quiet-zone field is further improved by reoptimizing the goal field. Measurement results are given for a test hologram fabricated on Teflon.     

An investigation into the amorphous phase separation characteristics of an ionomer glass series and a sodium-boro-silicate glass system

Amorphous phase separation of ionomer glasses, also known as fluoro-phospho-alumino-silicate glasses, of generic composition SiO₂-Al₂O₃-P₂O₅-CaO-CaF₂ were investigated. A sodium-boro-silicate glass system, which is known to undergo amorphous phase separation was also investigated. High Temperature Dynamic-Mechanical Thermal Analysis (DMTA), combined Differential Thermal Analysis/Thermo Gravimetric Analysis (DTA/TGA) and Scanning Electron Microscopy (SEM) were the principal analytical techniques used in this study. High temperature DMTA was used to measure the glass transition temperatures (T _g) of the original starting glass compositions, as well as being able to follow amorphous phase separation (APS) within the glass. High temperature DMTA traces of both the ionomer glasses and the sodium-boro-silicate glasses exhibited two maxima in tan , corresponding to two glass transition temperatures and demonstrating that amorphous phase separation of the parent glass into two glass phases had occurred. DTA/TGA of the ionomer glasses detected a glass transition and two crystallisation peaks for apatite and mullite, accompanied by a gradual weight loss of 1–3% on passing through the crystallisation region. The sodium-boro-silicate base glass showed no evidence of a glass transition, but a prominent glass transition was detected for a second sample which had undergone a heat-treatment of 240 min at 580°C. SEM analysis of the ionomer glass compositions revealed smooth spherical droplets of 2–15 nm while the background morphology appeared rough and speckled. A classic interconnected structure was observed for the sodium-boro-silicate glass.     

Method for angular alignment of birefringent fibers in fiber-opticpressure/strain measurement

A simple method for angular alignment of principal birefringence axes of a highly birefringent (HB) polarization-maintaining (PM) optical fiber is presented. The method is based on longitudinal strain-induced cross-coupling phenomena which occur in HB fibers and it can be straightforwardly applied to construct a fiber-optic pressure or strain sensor independent of disturbing thermal effects. The method is also particularly suitable for splicing birefringent fiber pigtails to laser diodes in all-fiber configuration for a fiber-optic pressure (strain) sensor     

Design of a bias magnetic system of a magnetostrictive sensor for flexural wave measurement

We report on an investigation of the voltage output from a magnetostrictive sensor for the measurement of elastic flexural waves in a cylindrical steel waveguide. Since the sensor performance is strongly influenced by the bias magnetic field, the bias field optimization is one of the most critical issues in the design of magnetostrictive sensors. For a magnetic system consisting of a yoke and an electromagnet, we formulate a method for optimizing yoke topology in order to maximize the sensor output. Both linear and nonlinear magnetization relations are considered in our analysis. For the verification of the performance of the proposed sensors, we conducted several experiments involving flexural waves to assess the performance of the optimized sensors, and we analyze their results here.     

Optimal pricing and core acquisition strategy for a hybrid manufacturing/remanufacturing system

Remanufacturing is one of the product recovery options where the quality of used products (cores) is upgraded to ‘as-good-as-new’ conditions. In this article, we consider a monopolist firm selling new and remanufactured products to quality-conscious primary customers and price-sensitive secondary customers, respectively, with one-way substitution, i.e. some primary customers may substitute new products by remanufactured products while secondary customers can never afford to buy new products. We develop economic models under two scenarios – when the supply of cores is unconstrained and when manufacturers have to procure cores at an acquisition price. The major observations of the article are as follows. A firm is better off when there is no constraint on the supply of cores. Even when cores have to be acquired at an acquisition price, the profitability is higher than that when the firm does not engage in remanufacturing activities. When a larger number of primary customers replace new products with remanufactured products, there is partial cannibalization of new product sales; however, the combined market share and profitability of the firm increase. When core supply is constrained and customers are less sensitive to core prices, the limited supply of cores may render remanufacturing an infeasible option for the firm. Therefore, firms should not only generate awareness among primary customers to buy remanufactured products, but also step up efforts to ensure a steady supply of cores. We conclude the article with managerial implications and directions for future research.     

Magnetorheological nanofinishing of BK7 glass for lens manufacturing

BK7 is a high-quality crown glass which is used where additional benefits such as temperature sensitive applications of fused silica glass are not required. Due to very low inclusion content with extremely low bubbles, BK7 glass can find its application in lens manufacturing. The present work focuses on nanofinishing of the BK7 glass specimen for ratifying its utility in practical application. A programmable logic controlled 3-axis motions are fed to the magnetorheological (MR) rotating tool for finishing the glass specimen. MR polishing fluid used for nanofinishing consists of deionized water, magnetic iron particles, and cerium oxide powder. Under the influence of magnetic field, the stiffened MR polishing fluid is assisted in reducing the surface roughness of glass up to nanolevel range. Optical properties such as transmittance, absorbance, and reflectance of finished BK7 glass are analyzed and found suitable for lens manufacturing. Results of higher surface quality with excellent finishing are obtained by the present MR finishing process. After 90?min of finishing, the surface roughness values R_a and R_q are reduced to 17 and 27?nm from the initial values of 41 and 57?nm, respectively. To study the surface morphology, scanning electron microscopy is performed on BK7 glass.     

A scheduling approach for a flexible manufacturing system

This paper discusses the scheduling problem of a particular flexible manufacturing system (FMS). The two main components of the FMS are a CNC turret lathe and a CNC machining centre. In the system a wide range of different jobs has to be processed. Each job consists of one or more processing operations on one or both machines. Important characteristics of the scheduling problem are sequence-dependent change-over times (on the turret lathe) and transfer times (on both machines and between the machines). The change-over times are caused by the need to exchange tools in the turret when a new part is going to be processed. The transfer times reflect the time needed to perform manual transportation and clamping activities between two subsequent processing (machining) operations of a part. In this paper a branch and bound algorithm is described based on an active schedule strategy. Solutions are compared to results obtained by a simple dispatching rule     

Design configuration for a closed-station,mixed-model assembly line: A filing cabinet manufacturing system

A closed-station assembly line with mixed models encountered in a filing cabinet manufacturing company is considered. Utility and idle times play an important role on the performance and economy of a closed-station system. This paper addresses a problem that minimizes the total cost of the utility and idle times caused due to different line parameters (launch interval, station length, starting point of work, upstream walk, locus of the operator's movement, etc.) and operation sequences of the mixed models. A mixed-integer-programming model for a closed-station system is developed to determine line parameters optimally. The model is tested on a three-station, mixed-model assembly line in a filing cabinet manufacturing system. The research shows that a set of line parameters is available for which the total cost of utility and idle times is minimal. Results also indicate that the minimum total cost of utility and idle times in a closed-station system decreases with line length. A sensitivity analysis is performed to study the effects of line and launch intervals in such a manufacturing line.