Identification of metrics and transition functions of pull system implementation

This research examines the problem of providing decision support for the transition from a traditional push production system to a pull system design. The methods presented include: a method for determining significant metrics of evolving production systems; a method for estimating associated transition functions; and a decision support system framework which gives guidelines for development of software employing these methods. An actual electronics assembly system provided a case study. Significant metrics for this system were determined to be quality, material flow congestion and system flexibility. Recursive equations for estimating these transition functions and a decision support system framework are given.     

Approximate Formula for the Contact between Truncated Surfaces and Frictional Characteristics of a Journal Bearing in Mixed Lubrication

This paper presents an approximate formula for the contact of a non‐Gaussian distribution of truncated surfaces, which is useful for mixed lubrication theory, and gives a method for the determination of the truncation parameters in this formula from a measured roughness profile. Using this approximate formula for a contact, the approximate formula for the friction coefficient of a journal bearing in mixed lubrication, which was previously proposed by the authors, is modified for truncated surfaces, and the frictional characteristics are demonstrated for various parameters of truncated roughness using the modified formula.     

A Symbolic computation method for automatic generation of a full vehicle model simulation code for a driving simulator

This paper deals with modeling and computer simulation of a full multibody vehicle model for a driving simulator The multibody vehicle model is based on the recursive formulation and a conespondmg simulation code is generated automatically from AUTOCODE, which is a symbolic computation package developed by the authors using MAPLE The paper describes a proceduie for automatically generating a highly efficient simulation code for the full vehicle model, while incorporating realistically modeled components The following issues have been accounted for in the procedure, including software design for representing a mechanical system in symbolic form as a set of computer data objects, a multibody formulation for systems with various types of connections between bodies, automatic manipulation of symbolic expressions in the multibody formulation, interface design for allowing users to describe unconventional forceand torque-producing components, and a method for accommodating external computer subroutines that may have already been developed The effectiveness and efficiency of the proposed method have been demonstrated by the simulation code developed and implemented for driving simulation     

Photopyroelectric technique for the measurement of thermal and optical properties of pigments in liquid solution

The analytical solution for the one-dimensional heat diffusion problem for a two-layer system, in the Beer-Lambert model for light absorption, is shown to be useful for the implementation of a novel photopyroelectric (PPE) methodology, for the measurement of thermal and optical properties for pigments in liquid solution. The PPE signal, as a function of the sample's thickness, is used for this goal. Exponential decay for the PPE amplitude, followed by a constant PPE phase, for solutions at low dye concentration and an exponential decay for the PPE amplitude but a linear PPE phase behavior for the higher concentrated ones are shown and are, respectively, used for the measurement of the optical absorption coefficient and thermal diffusivity for liquid samples. These PPE phase behaviors also provide a criterion to decide on the corresponding limit for optical and thermal properties measurement. This PPE methodology was tested by measuring the optical absorption coefficient (at 658 nm) and thermal diffusivity for solution of methylene blue and copper sulfate in distilled water at various concentrations. Independent measurements of optical properties, using a commercial spectrometer, were done to compare with the corresponding ones obtained with this PPE methodology, finding very good agreement to each other.     

Supersonic turbine stator design using dense gas with numerical method

In recent years, interest in renewable energy as a substitute for power generation using coal has increased. As a next-generation power system, the Organic Rankine cycle (ORC) system, which requires a multi-stage turbine or a supersonic turbine to generate a high power, has been shown to have high potential for such uses. In this paper, a dense gas is chosen as a working fluid and a supersonic nozzle is designed for a supersonic turbine with advantages in terms of cost, power density and layout. Two stators are designed using the Method of characteristics (MOC) for air and dense gas. To validate the numerical model, the nozzle designed for the air is compared to that of a PIV experiment from the open literature, and the results indicate a reasonable agreement. The nozzle for the dense gas is different as that needed for air. Therefore, the modified MOC is applied based on a polytropic assumption. In conclusion, an estimation of the performance is implemented with loss coefficients for a different number of blades. The number of blades is shown to be proportional to the loss coefficient. For example, the case with the biggest numbers of blades is affected the most by the shock effect that occurs at the trailing edge.

     

A Surface Area Calculation and CAPP System for Non-Axisymmetric Deep Drawing Products

In this paper a surface area calculation for non-axisymmetric deep drawing products of elliptical shape was constructed for the design of blank shapes of deep drawing products by using an AutoLISP function in AutoCAD software. A computer-aided process planning (CAPP) system for rotationally symmetric deep drawing products has been developed. In this study, a CAPP system for non-axisymmetric deep drawing products of elliptical shape was constructed using process sequence design. The system developed consists of four modules. The first is the recognition of shape module for recognising non-axisymmetric products. The second is a 3D modelling module for calculating the surface area for non-axisymmetric products. The third is a blank design module for creating an oval-shaped blank with an identical surface area. The fourth is a process planning module based on production rules that play the most important role in an expert system for manufacturing. The production rules are generated and upgraded by interviewing field engineers. The drawing coefficient, the punch and die radii for elliptical shape products are considered as the main design parameters. The suitability of this system was verified by applying it to a real deep drawing product. This surface area calculation and CAPP system should be very useful for reducing the lead-time for manufacturing and for improving the accuracy of products.     

动态联盟和敏捷供应链

动态联盟的建立是为了响应竞争环境的快速变化或一个新的市场机遇。它是一个结盟企业的利益共同体,是实现全球化敏捷生产的主要方式。敏捷供应链是支持动态联盟优化运行的重要使能技术。本文将主要针对在中国企业开展动态联盟的要求,困难和特点进行初步的分析,并重点围绕供应链的敏捷性,这一支持动态联盟优化运行的关键技术,进行深入的讨论,提出了一个基于智能代理和可重构原理的解决方案。     

Design and implementation of an efficient acoustically levitated drop reactor for in stillo measurements

We present the details necessary for building an efficient acoustic drop levitator with reduced electrical power consumption and greater drop stability compared to previous designs. The system is optimized so that the levitated drop may be used as a chemical reactor. By introducing a temperature, pressure, and relative humidity sensor for feedback control of a linear actuator for adjusting resonator length, we have built a completely automated system capable of continuous levitation for extended periods of time. The result is a system capable of portable operation and interfacing with a variety of detection instrumentation for in stillo (in drop) measurements.     

Towards an intelligent approach for CMM inspection planning of prismatic parts

This paper presents a model of prismatic parts (PPs) inspection planning on CMMs, in terms of an intelligent concept of inspection planning. The developed model is composed of Inspection Feature Construction, Sampling Strategy, Probe Accessibility Analysis, Automated Collision-Free Generation, and Probe Path Planning. In this model, the simulation of a measuring probe path is based on three algorithms: Algorithm for Measurement Points Distribution, Algorithm for Collision Avoidance, and Algorithm for Probe Path Planning. The simulation output is a measuring protocol for CMM UMM500. An experiment was performed on two PPs that have been produced for the purpose of this research. The inspection results show that all tolerances for both PPs are within the specified limits. The proposed model presents a novel approach for the automatic inspection and a basis for the development of an integrated, intelligent concept of inspection planning. The advantages of this approach imply the reduction of preparation time due to an automatic generation of a measuring protocol, a possibility for the optimisation of measuring probe path, i.e. the reduction of a time needed for the actual measurement and analysis of a workpiece, and an automatic configuration of measuring probes.     

多转子系统弯、扭耦合作用时临界转速的研究

导出了轴的弯、扭耦合传递矩阵和轴间的弯、扭耦合矩阵。在文［１］的基础上编制了多转子弯、扭耦合临界转速的通用程序。采用等效刚度、等效阻尼方法编制了多转子弯、扭耦合稳态不平衡响应的通用程序；研究了扭振、畸形结构、油膜刚度、油膜阻尼等因素对临界转速的影响；并对某型发动机转子进行了计算和分析     

A re-configurable cross-sectional imaging system for reverse engineering based on a CNC milling machine

This paper presents a novel reverse engineering digitizing system for full part geometry, which is based on a cross-sectional imaging device built in a NC milling machine. The system successively captures a picture for each planar cross-section contour of the part by end-milling and CCD imaging, and builds the geometry for both external and internal surfaces of the complex 3D part based on a set of the vectored cross-sectional contours. The system mainly consists of three components: a NC milling machine, a cross-sectional imaging device and a computer control unit. Some issues involving the principle and process flow of the system, encasing materials, cross-sectional imaging and NC code generation, etc. are described in detail. Built on an existing NC milling machine, a portable device for capturing the cross-sectional images is designed, which includes an isolated light source, a digital camera, a protective case, a rigid arm and a robust tripod. The device, connected to a computer control unit, serves as a highly flexible accessory for the NC milling machine, constructing the cross-sectional imaging system for reverse engineering. Furthermore, the error analysis and accuracy assessment of the system are also addressed. A typical case is discussed in detail to illustrate the applications of the system. Such a re-configurable digitizing system for reverse engineering offers a number of advantages, such as the functional extension of an existing NC milling machine, low costs, and rapid construction. As a result, this system provides a feasible and useful scheme for many enterprises to construct their own reverse measuring system based on existing equipment to aid in rapid product development and extend the function of existing equipment.     

Automated inspection of PCB components using a genetic algorithm template-matching approach

Automated inspection of surface mount PCB boards is a requirement to assure quality and to reduce manufacturing scrap costs and rework. This paper investigates methodologies for locating and identifying multiple objects in images used for surface mount device inspection. One of the main challenges for surface mount device inspection is component placement inspection. Component placement errors such as missing, misaligned or incorrectly rotated components are a major cause of defects and need to be detected before and after the solder reflow process. This paper focuses on automated object-recognition techniques for locating multiple objects using grey-model fitting for producing a generalised template for a set of components. The work uses the normalised cross correlation (NCC) template-matching approach and examines a method for constraining the search space to reduce computational calculations. The search for template positions has been performed exhaustively and by using a genetic algorithm. Experimental results using a typical PCB image are reported.     

Infrared image system for fire location

This paper describes a new sensor and interpolation technique for localizing a fire in a closed environment or in a highway tunnel. When a smoke detecting device warns for a presence of a fire, two thermopile arrays images are elaborated, to localize the, eventual, fire and to control fire extinguisher jet. This system is a very promising for highway tunnel and also as substitute for common fire sprinkler systems in closed rooms, due to its cost and relatively simplicity of installation.     

Stability criteria for manufacturing metal products on a horizontal metal casting and deformation plant

The Institute of Engineering Science and Metallurgy, Far-Eastern Branch, Russian Academy of Sciences, has developed and manufactured a plant for horizontal metal casting and deformation, which provides for making metal products of aluminum alloys with a desired cross section in a continuous mode from a melt. Data for the stability criteria for the developed integrated process and their application for evaluation of the reliability of the plant, and the quality of metal products manufactured, are given.     

Molecular Dynamics of Thin Lubricant Films on Sol-Gel SiO2 Surfaces for Thin Film Magnetic Disks

Mobility of molecularly thin lubricant film is an important issue in understanding boundary lubrication mechanisms and to develop reliable magnetic disk media. Intra-molecular mobility for a perfluorinated poly ether (PFPE), which is used as a disk lubricant, with two hydroxyl groups on a sol-gel SiO₂ surface, which is used for a protective overcoat for plated magnetic disks, was studied using nuclear magnetic resonance (NMR). Thin film viscosities for molecular segments were derived from a relaxation time. The viscosity for the hydroxyl segment is 1.8 to 11 times as much as that for a bulk lubricant at room temperature, and the viscosity rate increased with increasing temperature. For example, it increased 15 times at 100°C. The viscosities for the segments in a main chain were not different from that of bulk PFPE.

A spin-off calculation for the molecularly thin lubricant film with thin film viscosity, derived from the NMR method, shows that there is no thickness decrease after seven years.     

A Nondestructive Technique for Local Measurement of Dielectric Loss in Substrates of Integrated Circuits at Microwaves

A device for nondestructive measurements of dielectric loss in substrates of integrated circuits and film materials in a local 2-mm-diameter zone has been developed. The main element of the device is a coaxial resonator with a measurement hole at its end and a clamp for dielectric substrates in the form of a cylindrical waveguide that is evanescent for measurement frequencies. In such a system, emission of electromagnetic waves from the measurement hole is absent, although the phenomenon of emission is characteristic of a coaxial resonator with a hole to which a dielectric is applied. The absence of radiation loss simplifies the determination of the loss tangent for dielectric substrates. A formula for calculations and a measurement technique in the range of 10 GHz are presented.     

Precision Grinding of Mn-Zn Ferrite with In-Process Electro-Discharge Dressing

Ferrite is widely used as a material for magnetic heads for hard disks, but it is difficult to grind because its high hardness and brittleness. Therefore, a superabrasive diamond wheel is used for precision surface grinding of this material. However, the conventional dressing method cannot be applied to a superabrasive diamond wheel. This study describes a new method for carrying out effective in-process electro-discharge dressing (IEDD) of a superabrasive diamond wheel. Using IEDD, the surface roughness of the Mn-Zn ferrite was improved, and the grinding force was reduced. IEDD is a good method for obtaining efficient surface grinding of ferrite.     

High temperature controlled atmosphere experiments for catalysts in a transmission electron microscope

A new transmission electron microscopy (TEM) specimen preparation procedure for high temperature experiments using a controlled atmosphere specimen holder (HTCASH) has been developed. It is designed for studying the microstructure of catalyst specimens before and after treatments in various gases. The procedure involved (1) finding a new formula for the embedding material, (2) devising a new method of making specimen supports, and (3) developing a method for removing the embedding material after the specimen has been microtomed. These techniques were then brought together to produce the ideal specimens for the HTCASH experiments. As an extra benefit, this procedure is also suitable for preparing specimens for ultrahigh resolution imaging experiments. The application of the new procedure in HTCASH experiments is illustrated through a high temperature reduction of a Co/SiO₂-923 catalyst.     

Characterization of microscope objective lenses from 1,400 to 1,650 nm to evaluate performance for long-wavelength nonlinear microscopy applications

We have demonstrated a simple method for characterization of objective lens performance at longer wavelengths for 3PLSM and THG imaging. We investigated a range of air and oil-immersion objective lenses across a wavelength range of 1,400-1,650 nm using a synchronously pumped optical parametric oscillator laser source. In the first instance, we investigated the percentage light transmission across this spectral range. Second, we used a simple second harmonic autocorrelation pulse measurement technique to study the dispersion properties of these lenses at the range of input wavelengths. For the objective lenses investigated, we observed pulse broadening on the order of around 4%-7% for air immersion lenses and 9%-12% for oil immersion lenses. Even for the greater dispersion incurred by the application of the oil immersion lenses, these objectives are suitable for longer wavelength application in conjunction with a suitable light source. The same techniques could easily be applied for a larger range of objective lenses and adapted for alternative spectral windows and pulse durations.     

Lateral resolution of the scanning tunnelling microscope

A theoretical study of the current distribution in a model which extracts the prominent characteristics of a tip-surface geometry in a scanning tunnelling microscope is presented. The sample is a Sommerfeld metal with a planar surface while the tip, also made of a Sommerfeld metal with a planar surface, presents a hemispherical protrusion. Schrödinger's equation is solved by using a form of the finite element method suitable to treat the three-dimensional tunnelling problem. We have derived the current distribution for several values of the protrusion radius and for various gaps between the electrodes. From these results, we investigate the ideal resolution of the scanning tunnelling microscope for realistic values of these geometrical parameters. Though applied to a rather simple model, at this stage, our method appears to be a suitable scheme for further, more refined computations, accounting for the detailed atomic structure of the electrodes.