Real-time tracking control of electro-hydraulic force servo systems using offline feedback control and adaptive control

This paper focuses on an application of an electro-hydraulic force tracking controller combined with an offline designed feedback controller (ODFC) and an online adaptive compensator in order to improve force tracking performance of an electro-hydraulic force servo system (EHFS). A proportional-integral controller has been employed and a parameter-based force closed-loop transfer function of the EHFS is identified by a continuous system identification algorithm. By taking the identified system model as a nominal plant model, an H_∞ offline design method is employed to establish an optimized feedback controller with consideration of the performance, control efforts, and robustness of the EHFS. In order to overcome the disadvantage of the offline designed controller and cope with the varying dynamics of the EHFS, an online adaptive compensator with a normalized least-mean-square algorithm is cascaded to the force closed-loop system of the EHFS compensated by the ODFC. Some comparative experiments are carried out on a real-time EHFS using an xPC rapid prototype technology, and the proposed controller yields a better force tracking performance improvement.     

智能螺丝紧固系统的研究与开发

介绍高频头智能螺丝紧固系统,包括自动送料系统、自动点胶系统、自动锁紧系统、自动卸料系统及自动控制系统。该系统成本约仅为同类进口设备价格的1/3,投入使用后,锁螺丝速度达40~60pcs/min,与手工操作相比,工作效率提高10倍。     

Optimized performances comparison of organic Rankine cycles for low grade waste heat recovery

An organic Rankine cycle (ORC) can be applied to recover the low-grade waste heat. In this paper, the performances of five different types of ORC are evaluated. These configurations include a simple ORC, an ORC with an internal heat exchanger (IHE), an ORC with an open feed organic fluid heater (OFOH), an ORC with a closed feed organic fluid heater (CFOH), and an ORC with a reheater. First, the feasible working region is defined for an ORC operating together with an internal combustion engine. Subsequently, the thermal efficiency of each ORC is maximized using a genetic algorithm. Finally, the characteristics of each ORC are analyzed and compared using a combination of the first law and second law method. Our analysis indicates that the ORC with an IHE showed the best thermodynamic performance. The ORC with an OFOH and the ORC with a CFOH are sub-optimal while the simple ORC and the ORC with a reheater are the last choice. The effects of the expander inlet pressure, the condenser outlet temperature and the expander isentropic efficiency on system performance of each ORC were also analyzed.     

Intense flexural and torsional waves in an elastic bar

The paper considers the problems of propagation of an intense flexural wave in a twisted bar and an intense torsional wave in a bar with an initial curvature in the context of a geometrically nonlinear model of flexural and torsional vibrations of an elastic bar.     

Pre-design model for redox flow battery design

Owing to complex configurations and the multi-physics phenomenon in a Redox flow battery (RFB), designing an RFB flow frame through Computational fluid dynamics (CFD) or experimentally requires high design costs. As an alternative approach, a compartment model can be applied to the design of an optimal RFB flow frame. In this study, we developed a pre-design model to estimate the parameters related to the energy efficiency of an RFB. A key factor of the proposed model is applying a classical pipe network theory and an electric circuit analogy to an RFB flow frame and stack. The pre-design model enables an estimation of the total pressure drop, flow rate distribution, and shunt current at the RFB cells or stack. Model-based estimates show good agreement with CFD and experimental results.     

偶数齿带式烧结机的研究

研究的偶数带式烧结机的星轮，是将星轮齿设计成偶数个，由匀速齿齿郭曲线和复俣齿（加速、匀速齿组合）齿廓曲线组成的齿廓，相间排列成的新型烧结机星轮。给出与之相匹配的该机头尾星轮弯道曲线方程。实现了台车列的匀速运动及单台车的追赶运动。可为偶数齿烧结机设计和奇数齿烧结机改造提供理论依据和实用参考。     

Hard pressed [glass pressing]

Pressing itself was the first step to automation in the glass industry, but the job of automatically transferring a quantity of molten glass from the furnace to the moulds on an automatic press proved an obstacle to the complete mechanisation of the pressing process. it was not until 1915 that an automatic device for feeding a gob of glass to a mould on an automatic press was perfected in the USA. Fully automatic production of pressed glassware became feasible. The author gives an updated outline of the automatic production of pressed glassware     

电厂灰水自动加酸控制系统

本文介绍了自动加酸控制系统在安庆石化热电厂灰场排水中的应用。     

一种基于网络的面向拆卸设计的评价方法

面向产品的拆卸设计是绿色设计中十分重要的研究领域。本文构建了网络环境下面向产品拆卸设计的体系结构，研究了面向拆卸设计的产品结构模型。结合Z50E装载机的具体实例，进行了产品可拆卸性的评价分析及相应的设计修改建议。     

An inverse shock response spectrum

The shock response spectrum (SRS) is a tool commonly used by application engineers that characterizes the severity of a transient acceleration. Due to the definition of the SRS, neither an analytical nor a unique inverse exists for an arbitrary function. An SRS presented without any temporal information makes creating a corresponding acceleration time history for an experimental or numerical study prohibitively difficult without a rigorous method to determine an inverse of the SRS (a corresponding time history). The present work develops a method to calculate an inverse of an arbitrary SRS using three sets of well characterized basis functions: an impulse function, a sine function/damped sine function, and a modified Morlet wavelet. These three basis functions are specifically chosen for the properties of their transformations: the impulse introduces a constant increase to the SRS above a given frequency, the sine wave introduces a narrow peak at a given frequency, and the Morlet wavelet introduces a plateau with an adjustable width and relative height. Using the definition of the SRS, the transformations of the basis functions are calculated and these expressions are used to derive a methodology for calculating an inverse SRS. The effectiveness of the method is demonstrated by several examples. The quality of an inverse SRS is evaluated by comparing the SRS of the inverse to the target SRS. This method is developed in order to provide a quick estimate of a corresponding time history; in applications where a higher fidelity representation of the SRS is needed than can be provided by the method developed, a genetic algorithm is used to optimize the coefficients of the basis functions. Given a sufficient number of basis functions for the optimization, the resulting SRS can almost exactly match a randomly generated target SRS that is nonzero over the frequency range considered. For applications in which the permissable basis functions are limited (such as for an experimental test apparatus), an extension of the genetic algorithm method is discussed.     

An Asymptotic Method for Solving the Problem of Identifying a Curvilinear Crack in an Elastic Layer

Russian Journal of Nondestructive Testing - We solve an inverse geometric problem of identifying an internal curvilinear defect in an orthotropic elastic layer. Defect parameters (location, depth,...     

Tribological behavior of Fe-based bulk metallic glass

The unlubricated tribological characteristics of coating layers containing an Fe-based amorphous matrix have been investigated in air using an alumina ball with a diameter of 3.1 mm. From the ball-on-disk test system, the friction coefficient could be measured for up to 3,000 seconds. The temperature changes on the worn surfaces were also simultaneously measured using an infrared thermometer. Three different types of coating layers having an Fe-based amorphous matrix, an Fe-based amorphous matrix with embedded Ni-based self-fluxing alloy particles, and an Fe-based amorphous matrix with embedded WC particles were prepared through a high velocity oxy-fuel (HVOF) process. Although the coating layers have certain levels of porosity, unique frictional characteristics attributed to the amorphous matrix were observed during the friction tests. Compared with conventional bearing steels such as AISI 521000 (Hv=840), excellent tribological and wear characteristics were obtained, demonstrating that an Fe-based bulk metallic glass powder is a viable engineering material for practical anti-wear coating applications.     

A contact problem for an elastic half-plane with rigid coating

Solution of contact problems on soft or rigid coatings of an elastic half-plane is of great practical interest. The present paper is aimed at considering the problem of interaction between a rigid biquadratic die and an elastic half-plane through a thin rigid coating. We have derived an integral equation for the problem under study and constructed its approximate solution by an asymptotic method.     

A fuzzy model for assessment of organization vulnerability

There are many factors that can make an organization and its business unsafe and endanger its sustainable development. Exposure of an organization to existing risks may vary and it can be studied from different perspectives, but undoubtedly increased vulnerability of an organization can lead to disaster. This paper investigates the general vulnerability of an organization and proposes a model for its assessment. The process approach has been employed to define the model of an organization, as well as the fuzzy approach for mathematical modeling of uncertainties. An assessed value of organization vulnerability is obtained by using linguistic expressions which are close to human thinking. The mathematical model of organization vulnerability is solved through fuzzy sets with input data defined by a management team. The model for vulnerability assessment is verified through an illustrative example. The obtained results represent an input for future research which should include a good benchmark base for the tested organizations and their continuous improvement.     

A flaw in a cylinder

The problem of magnetostatics for the following model of a defective body is considered: an inclusion in the form of an infinite cylinder with an arbitrary cross section, which is limited by a smooth contour, is inside an infinite magnetic cylinder with a circular profile. An integrodifferential equation with respect to the strength vector of the resulting magnetic field, which contains an integral only over the boundary of the flaw cross section, was derived for this type of body. An algorithm for calculating such a field for the case of an inclusion in the form of a circular cylinder, which is misaligned relative to the large cylinder, was developed. The results of this study can be used in practice when testing cylindrical items with extended flaws.     

Unsteady characteristics of laminar free convection in an enclosure in the presence of power law fluid at Ra = 107

Journal of Mechanical Science and Technology - The present study deals with an unsteady laminar free convection inside the annuli confined between an outer square enclosure and an inner circular...     

Efficient heating with a controlled microwave field

To uncover the intriguing non-thermal microwave effect, an experiment was conducted using an amplifier rather than an oscillator as the radiation source, which was injected into an applicator with strong electromagnetic field enhancement. The characteristics of the applicator are discussed and the enhancement of the microwave field is illustrated and explained. Thermal distribution is simulated based on the calculated microwave field profile. It was demonstrated that the proposed system heated a SiC susceptor to a temperature of 637 °C with the input power of 60 W. The reasons for such an efficient heating are discussed.     

Use of backscattered electron detector arrays for forming backscattered electron images in the scanning electron microscope

The backscattered electron (BSE) signal in the scanning electron microscope (SEM) can be used in two different ways. The first is to give a BSE image from an area that is defined by the scanning of the electron beam (EB) over the surface of the specimen. The second is to use an array of small BSE detectors to give an electron backscattering pattern (EBSP) with crystallographic information from a single point. It is also possible to utilize the EBSP detector and computer-control system to give an image from an area on the specimen--for example, to show the orientations of the grains in a polycrystalline sample ("grain orientation imaging"). Some further possibilities based on some other ways for analyzing the output from an EBSP detector array, are described.     

Decrease in the ignition pressure of anomalous glow discharge in a magnetron with an ion-beam-irradiated cathode

The influence of an ion beam injected along the axis of the anode electrode of a planar magnetron on the initiation of an anomalous low-pressure glow discharge in a magnetron has been considered. The characteristics of the discharge ignition at pressures <8 × 10^?2 Pa and the properties of a planar magnetron with an ion-beam-irradiated cathode are determined. It is established that the discharge ignition voltage decreases with an increase in the ion energy and exhibits a threshold behavior as a function of the ion-beam current. It is shown that there is a prospect for extending the functional capabilities of planar magnetrons through matching of the modes of sputtering of the magnetron anode and cathode by an ion beam and plasma ions of an anomalous glow discharge, respectively.