投入式油水界面测量系统精度分析

对一种低价实用的投入式压力传感器储液罐液位和油水界面及密度自动检测装置的精度进行分析,得到其适用范围与优点。     

Freestanding lipid bilayers as substrates for electron cryomicroscopy of integral membrane proteins

Phospholipid bilayers, 40 Å thick, were generated as electron microscope substrates by submerging copper grids overlaid with holey plastic through a lipid monolayer on a water surface. Previously formed proteoliposomes containing single‐particle membrane proteins in their bilayers were then fused into the newly formed bilayer substrate. To demonstrate this methodology, multi‐drug resistance protein P‐glycoprotein was incorporated into these bilayers and imaged by fixed beam microscopy and scanning transmission electron microscopy.     

铠装旁热式热电偶水位传感器的实验研究

介绍了水位监测用铠装旁热式热电偶液位传感器的测量原理和实验研究。实验重点研究了传感器的动态响应和水位淹没与脱离传感器敏感部位时的差分热电偶的温差输出波形。实验表明,应用阈值或温差变化的斜率来判别水位的方法能有效地缩短传感器的响应时间和增加测量的可靠性。实验研究结果表明,铠装旁热式热电偶液位传感器完全适用于水位及其他液位监测,尤其适用于核场高可靠性要求的场合。     

Muscle regeneration in holothurians.

The muscle system of holothurians includes visceral (coelomic epithelium) and somatic (longitudinal muscle bands, retractors of aquapharyngeal complex) musculature. Visceral musculature regeneration is achieved by the transformation of myoepithelial cells via their dedifferentiation, migration, proliferation, and redifferentiation. During somatic muscle regeneration the new muscle bundles are formed due to dedifferentiation, migration, and immersion of the coelomic epithelial cells into the connective tissue. While submerging, the epithelial cells transform into myocytes and begin to produce myofibrils in their cytoplasm. Concomitantly, a basal lamina is formed around the group of myogenic cells, separating them from the surrounding extracellular matrix. The myohistogenesis is accompanied by a conspicuous DNA-synthetic activity. Proliferation is insignificant and seems to be of no essential importance for muscle regeneration. The synthesis of DNA followed by no cytokinesis results in an increase in the amount of DNA of myocyte nuclei.     

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.     

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.     

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.     

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.     

An intelligent concurrent design task planner for manufacturing systems

Product design is an integral component of manufacturing systems. This paper presents a prototype intelligent concurrent design task planner, which combines the strength of genetic algorithms and an iterative design analyser for the scheduling of a complex design process of a manufacturing system. It accounts significantly for shortening the time-to-market of a product, and hence, improves the agility of a manufacturing system. The proposed prototype attempts to schedule the design process inherently containing iteration, which is caused by the interdependencies among tasks and leads to prolonged lead-time and increased cost on the whole time-span of introducing a product. Genetic algorithm (GA), as one of the effective optimisation techniques, is embodied in the prototype to search for the optimal schedule for a design process for the goal of satisfying the managerial objective under resource constraints. The iterative design analyser, which is basically an analytical tool for design iteration, is utilised to estimate the time and engineering cost spent on the design process for each candidate schedule. Considering the unpredictable length of a schedule for iterative design process, a novel chromosome representation scheme and unique crossover and mutation operators have been introduced. A case study conducted on a burn-in system of a manufacturing company has illustrated the effectiveness of the proposed prototype.     

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.     

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 novel dynamic model for multiple configurations of machine tools using a coordinate transformation method

Virtual machine tools have been used widely for simulating designs in computer environments to determine optimal design parameters without the need for manufacturing prototypes. Machine tools include different multiple configurations that are designed to be suitable for the differing requirements of production. To date, studies on dynamic analysis have been limited to a few-axis machine tools of a specific configuration, such as a 3-axis milling machine or a 4-axis grinding machine. Here, we propose a novel method to focus on the dynamic analyses of multi-axis machines with differing multiple configurations. The motion equations for multiple degrees of freedom of linear and rotary axes are established by a Lagrange energy method, equilibrium equations, and Newton’s second law. This technique formulates the motion equations for each axis, and then further develops them for a multi-axis machine through a combination process and a transformation matrix. The library includes five dynamic model components, built to simulate 1236 different configurations of a machine tool. A dynamic analysis was applied to a control system to simulate the control signals of a virtual machine, which include stepped, ramped, curved, sinusoidal, and circular responses, and frequency response functions. The simulated and experimental results demonstrated that the method has high accuracy and reliability for one-, two-, and four-axis machine tools. Thus, this method can simulate the dynamic analyses of multi-axis machines and different multi-configurations without the need to build a specific configuration for each machine. It is recommended for selecting optimal motors, design parameters, and control parameters of the multiple configurations in a machine tool.     

A dimensioning and tolerancing methodology for concurrent engineering applications II: comprehensive solution strategy

Dimensioning and tolerancing (D&T) is a multidisciplinary problem which requires the fulfillment of a large number of dimensional requirements. However, almost all of the currently available D&T tools are only intended for use by the designer. In addition, they typically provide solutions for the requirements one at time. This paper presents a methodology for determining the dimensional specifications of the component parts and sub-assemblies of a product by satisfying all of its requirements. The comprehensive solution strategy presented here includes: a strategy for separating D&T problems into groups, the determination of an optimum solution order for coupled functional equations, a generic tolerance allocation strategy, and strategies for solving different types of D&T problems. A number of commonly used cost minimization strategies, such as the use of standard parts, preferred sizes, preferred fits, and preferred tolerances, have also been incorporated into the proposed methodology. The methodology is interactive and intended for use in a concurrent engineering environment by members of a product development team.     

机器人多手指抓取和适应性夹具夹持的封闭性和可达性

本文讨论了机器人多手指抓取和适应性夹具设计的共同特点和理论基础。提出了刚体点接触下的约束锥和自由锥的概念,研究了两者的对偶性;推导了定位确定性条件,抓取封闭性条件,可达性和可分离性条件;严格定义了刚体点接触的约束度和自由度;建立了刚体在点接触约束下瞬时运动分析的几何理论,给出了封闭性和可达性的代数判别准则和计算机自动判别方法。为机器人抓取规划,适应性夹具设计提供了理论依据和实现方法。     

Networked control of industrial automation systems—a new predictive method

A new method for real-time prediction of uncertain network transmission time delays and a method for closed-loop control of manufacturing and industrial plants through networks are introduced. The proposed delay prediction method is based on the multilayer perceptron neural model. In order to minimize the number of neurons in the first layer of the network and hence reducing the computational burden in a real-time implementation, a method for determination of the Markov order of the time delay sequence is presented. Using the predicted delay, and a zero-order hold equivalent discrete-time model of the plant, a time varying state feedback control algorithm with a real-time gain updating strategy is proposed. A sufficient condition for closed-loop stability is also derived using the switching theorem for linear systems. The proposed method is shown, through two industrial networked case studies, namely, a DC motor driving a transportation roller for paper sheets and a milling machine. Simulation studies depict the efficacy of the proposed method in controlling such challenging problems.     

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.     

基于约束图谱旋量分析方法的调平机构约束设计

约束图谱分析方法从自由度和约束的视角处理机械设计问题,由于自由度和约束概念的一般性,因而该方法对机械设计问题具有广泛的指导意义。从刚性机构及机械接口通用设计方法角度,将旋量理论应用于约束图谱分析方法研究,采用纯力旋量表示点接触约束,采用运动旋量表示自由度,给出约束图谱分析几何概念的旋量描述;基于互易旋量,提出自由度超平面的概念,用以描述点接触约束的单向性,给出并联机构自由度分析及串联机构约束分析方法;在此基础上,提出自由度线等价原则及自由度约束互补原则的代数基础,由此形成集成几何概念的约束图谱旋量分析方法。以光刻机调平机构为例开展应用研究,指出常用2-SPS&1-SP调平机构欠约束和欠确定运动问题,进而提出1-PSV&1-PSE&1-S调平机构,介绍约束图谱旋量分析方法在机构约束设计问题中的应用。     

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     

A handheld support system to facilitate stereological measurements and mapping of branching structures

BranchSampler is a system for computer-assisted manual stereology written for handheld devices running Windows CE. The system has been designed specifically to streamline data collection and optimize sampling of tree-like branching structures, with particular aims of reducing user errors, saving time, and saving data in formats suited for further analysis in other software, for example, a spreadsheet. The system can be applied in a wide range of applications, from biomedical science to agriculture and horticulture. It can be applied for sampling nested generations of lung bronchioles and renal arterioles or for collection and optimizing sampling of crops for precision agriculture. Although the system has been designed specifically for sampling branching structures, it is sufficiently flexible to be used for other applications involving nested stereological designs. We describe the system specifications, software and Graphical User Interface development, functionality and application of the handheld system using four examples: (a) sampling monkey lung bronchioles for estimation of diameter and wall thickness (b) sampling rat kidney for estimating number of arteries and arterioles in a specific generation (c) mapping fruit (apple) tree yield in an orchard and (d) estimating the total leaf surface area of chrysanthemum plants in a greenhouse.     

往复式注水泵振动监测判断标准的研究制定

为对往复式注水泵进行状态监测与故障诊断,研究制定了往复式注水泵的振动监测判断标准,通过1台新泵的台架试验和注水站6台泵的测试分析,确定了监测布点方案,测量参数,分析频率,各测点振动警限值,绘制了警限值表和警限值线图,本判断标准的制定为往复式注水泵振动监测提供了科学的依据,具有工程实用价值。