Design investigation of a linear motor for artificial heart driving

The authors have been considering the use of a linear pulse motor (LPM) as a driving source of a totally implantable artificial heart (TAH), and have developed a series of artificial heart models that incorporate such a motor. The newly developed linear-type TAH (linear TAH) has two blood-pumps, which are inflated and deflated alternately by the LPM, causing a pusher plate to pulsate the blood. This paper deals with the performance calculation of the LPM using the loading ratio. Some motors manufactured for driving TAHs were then selected to compare their machine parameters. The selected motors were LPM, linear oscillatory actuator, brushless dc motors, and ultrasonic motor. Two parameters were selected for the comparison: the mechanical output/volume ratio and the motor constant. The results may be summarized as follows: 1. The LPM was designed based on the loading ratio, and the kinetic thrust and velocity were obtained at the range of 77 newtons and 80 mm/s, respectively. 2. The loading ratio of the LPMs were more than eight times larger in comparison with the rotary motors that were used in industrial machines. 3. The motor constants of the LPMs were recognized to be one figure larger than that of the brushless dc motors. In order to reduce the volume of the linear TAH, it is necessary to increase the drive velocity of the LPMs. Application of the linear motor to a nonpulsatile artificial heart will be one way to achieve this. © 1998 Scripta Technica, Electr Eng Jpn, 123(1): 43–50, 1998     

Position sensorless drive of linear pulse motor for suppressing transient vibration

The linear pulse motor (LPM) has been widely used because of its simple structure and ease of control without the use of feedback. However, the transient vibration inherent in the LPM results in degraded response performance. The fastest way to suppress the vibration is to close the control loop by means of a position feedback sensor. But the straightforward use of such a sensor feedback results in high cost and a complicated configuration and therefore sacrifices the structural advantages of the LPM. The authors therefore propose Kalman filter‐based position sensor control as a means of suppressing transient vibration. In this proposed control method, the mover position and speed are optimally estimated by using an extended Kalman filter applied to the nonlinear state equation of the excitation winding circuits. The effectiveness of this control method is demonstrated by experiments on a prototype LPM system using a DSP. © 2000 Scripta Technica, Electr Eng Jpn, 134(1): 53–63, 2001     

Use of compensating magnets to reduce thrust imbalance in cylindrical linear pulse motors

A linear pulse motor (LPM) has many advantages for a high-accuracy positioning actuator because it has linear motion without any mechanical link. The flat-type LPM generally is used in many industrial applications. However, it has a disadvantage in that the mover support mechanism becomes complex and heavy because the attraction force between the stator and the mover is very large. As the attraction force is balanced in the cylindrical structure, the cylindrical LPM is allowed to have a simple and lightweight support mechanism. The inset magnet-type cylindrical LPM, which has a permanent magnet between the A-phase and B-phase stator, has such merits as a magnet of simple shape and a reduction of the motor diameter. Its weak point is that thrust unbalance occurs because the magnetic flux pass of the outer poles is longer than that of the inner poles. The thrust unbalance decreases the pull-in thrust force and increases the positioning error. This paper proposes two practical methods to improve the thrust unbalance: 1) the exciting current adjustment; and 2) the method with compensation permanent magnet. These effects are examined with theoretical and experimental results.     

Intra-aortic balloon pump driven by a linear pulse motor

The Intra-Aortic Balloon Pump (IABP) is an effective device in assisting circulation. However, a small-sized IABP is required in related fields. This paper proposes a new small-sized IABP which is driven by a Linear Pulse Motor (LPM) rather than an air-driven motor. In general, the LPM has advantages of high thrust/input power and good controllability. The developed LPM for the IABP drive has high thrust/input power of 19.9 newtons/W. It also has kinetic thrust of 270 newtons at the range of speed from 100 to 140 mm/s. The IABP using the LPM has an extremely simple construction. As the result of mock testing, the IABP using an LPM not only gives the same performance as the ordinary air-driven IABP, but the mass of the IABP will be reduced to half the size of the ordinary one.     

基于相位信息的旋转、缩放、位移不变的图像水印技术

数字水印技术将在电力系统中得到广泛应用。这些应用包括数字信号版权保护、内容认定、质量估计、数据库索引和检索等。该文介绍一种基本上不受旋转、缩放、位移影响的新的数字图像水印技术。笔者首先对原始图像进行傅立叶变换，然后再将水印埋嵌在该傅氏变换的幅度频谱的对数极坐标域。图像在空域中的旋转对应于该对数极坐标域中沿着角坐标的位移；图像在空域中的缩放对应于该对数极坐标域中沿着对数半径坐标的位移；而图像在空域中的水平位移对该对数极坐标域没有影响。为了计算和校正旋转和缩放在该对数极坐标域中造成的水印位置平移，笔者提出一种新的滤波方法。该滤波方法需要使用原始图像对数极坐标域中的一小方块信息来计算水印位置的平移。该水印技术能以最小的代价避免穷举搜索，以节省计算时间和减少误检率。实验数据证明该技术非常实用。     

基于推力观测器的直线式交流伺服系统滑模变结构控制

针对直线式直接驱动交流伺服系统,提出了一种新型滑模变结构控制方案。通过负载推力观测器的设计和扰动的前馈补偿,有效地削弱了变结构控制产生的抖振。在系统滑模设计中,采用积分补偿法进一步削弱系统的抖振。仿真和实验结果表明,该方案不但克服了直线式永磁同步机推力波动对系统性能的影响,而且对系统参数变化和负载扰动具有很强的鲁棒性。     

改进先导传播模型法500 kV架空线路雷电绕击分析

用先导传播模型法(leader progression model,LPM)分析架空输电线路的防雷特性的关键在于主要模型参数、先导起始和拦截判据的确定。参考国际上对长间隙放电研究的成果,考察LPM中参数和判据的适用性,提出对LPM的判据改进。并且考虑雷云的背景静电场和线路运行电压的影响,建立改进的先导模型法。经改进的LPM应用于平原和山区地形条件下的500 kV架空线雷电绕击分析计算。改进前后的计算结果与运行经验数据的对比分析表明,该改进先导模型法的计算结果与我国500 kV架空线路的运行经验数据相吻合。     

单相受热管集中参数简化模型的讨论

对单相受热管集中参数模型进行简化,将管壁金属热容与工质热容合并考虑,由此得到的集中参数简化模型,由于模型简单,在工程中得到广泛的应用。本文以理论分析为基础,以分布参数模型为标准,对简化模型与集中参数模型所具有的模型精度进行了全面的定量比较。文中还分析了分段数对集中参数及其简化模型精度的影响,发现存在很大差别。对于简化模型存在的最佳分段数,文中也作了推导。     

直线步进电动机闭环控制系统研究

根据直线脉冲电机的特性和控制要求,以89C51单片机为核心控制单元,采用专用集成驱动芯片PBL3717A作为功率驱动器件进行闭环控制并通过硬件和软件设计,实现对直线脉冲电机的精确定位和调速,解决了直线脉冲电机行程末端的机械冲击问题。     

Optimization of transmission line planning including securityconstraints

The authors describe an automatic way of finding the least-cost method of securing a given power system. The objective is to minimize the present cost of building additional lines to make the system secure due to single contingencies, subject to the technical constraints with and without line outages. A second approach to the problem, heuristic in nature, is also illustrated and compared to the results of the first method. All network synthesis is based on the DC power flow model. A six-bus network is used to illustrate the methods, and solutions obtained using a standard mixed-integer linear programming computer package, MIP/370, are given     

电炮用磁通压缩脉冲直线发电机的数学模型

电炮用磁通压缩脉冲直线电机是一种理想的电炮电源,但它的研究尚不成熟。该文首次建立了描述该发电机工作过程的系统的数学模型,为它的成功研制提供了理论依据。该数学模型由电磁学模型和力学模型组成。电磁学模型由电路方程组、一维电磁场和温度场扩散方程组、动态电感方程、动态电阻方和磁通损耗方程构成,而力学模型由电枢运动方程组和二维均相流体力学方程组构成。     

Modeling and vector control of planar magnetic levitator

The authors designed and implemented a magnetically levitated stage with large planar motion capability. This planar magnetic levitator employs four novel permanent-magnet linear motors. Each motor generates vertical force for suspension against gravity, as well as a horizontal force for drive. These linear levitation motors can be used as building blocks in the general class of multi-degree-of-freedom motion stages. In this paper, they discuss the electromechanical modeling and real-time vector control of such a permanent-magnet levitator. They describe the dynamics in a dq frame introduced to decouple the forces acting on the magnetically levitated moving part, namely, the platen. A transformation similar to the Blondel-Park transformation is derived for commutation of the stator phase currents. They provide test results on step responses of the magnetically levitated stage. They show 5 nm RMS positioning noise in x and y, which demonstrates the applicability of such stages in the next-generation photolithography in semiconductor manufacturing     

A tutorial description of an interior point method and itsapplications to security-constrained economic dispatch

The authors deal with the use of successive linear programming (SLP) for the solution of the security-constrained economic dispatch (SCED) problem. They tutorially describe an interior point method (IPM) for the solution of linear programming (LP) problems, discussing important implementation issues that really make this method far superior to the simplex method. A study of the convergence of the SLP technique and a practical criterion to avoid oscillatory behavior in the iteration process are also proposed. A comparison of the proposed method with an efficient simplex code (MINOS) is carried out by solving SCED problems on two standard IEEE systems. The results show that the interior point technique is reliable, accurate, and more than two times as fast as the simplex algorithm     

Improvement in stabilization of launching performance and launching velocity using linear accelerator

This paper describes the improvements in launching stability and launching velocity of the linear accelerator (LAC). The authors have designed and produced a railgun using the LAC for weaving loom shuttles. The LAC is an electromagnetic launcher which enables a projectile to be launched at a speed of more than 50 m/s. Basically, it consists of a unipole linear dc motor and operates the same principle as dc rotary motors, the most difficult problem in this system being the stabilization of the current collection on the projectile. Then, various launch experiments have been conducted. As a result, the carbon projectile was launched at a speed of 73 m/s using double-state-type LAC.     

Neural networks approach for solving economic dispatch problem withtransmission capacity constraints

This study presents a new approach using Hopfield neural networks for solving the economic dispatch (ED) problem with transmission capacity constraints. The proposed method is based on an improved Hopfield neural network which was presented by Gee et al. (1994). The authors discussed a new mapping technique for quadratic 0-1 programming problems with linear equality and inequality constraints. The special methodology improved the performance of Hopfield neural networks for solving combinatorial optimization problems. The authors have now modified Gee and Prager's (GP) method in order to solve ED with transmission capacity constraints. Constraints are handled using a combination of the GP model and the model of Abe et al. (1992). The proposed method (PHN) has achieved efficient and accurate solutions for two-area power systems with 3, 4, 40 and 120 units. The PHN results are very close to those obtained using the quadratic programming method     

Extraction of 40 Hz EEG bursts for chaos analysis of brain function

The authors describe the extraction of 40 Hz burst EEG activity in the face of electromyogram (EMG) noise. Extraction is done using time- and frequency-domain analysis, with a neural network to automate the task. The data are then analyzed using chaos theory to show how the 40 Hz activity can be used to recognize differences in cognitive states     

Online monitoring of dyskinesia in patients with Parkinson''s disease

Discusses utilizing wearable movement sensors to successfully detect and assess severity of Parkinsonion symptoms in daily life. The authors describe the present state-of-the-art of online monitoring of motor behavior. They focus on modern monitoring equipment and on new analysis tools, which allow a quantitative detection and assessment of dyskinesias throughout the day, by an objective, unsupervised rating of dyskinesias using clinical rating scores.     

A new Benders decomposition approach to solve power transmissionnetwork design problems

In this paper we describe a new Benders decomposition approach to solve power transmission network expansion planning problems. This new approach is characterized by using a linear (0-1) disjuntctive model which ensures the optimality of the solution found and by using additional constraints, iteratively evaluated, besides the traditional Benders cuts. The results obtained, considering a real world power transmission network expansion planning study with the southeastern Brazilian system, show the efficiency of this approach     

复合绝缘子表面湿润特性建模分析

研究复合绝缘子在雾中的湿润特性有利于分析污闪机理,根据污闪试验中泄漏电流工频分量幅值的变化,利用一次分段曲线简化和替代原有数据,总结了描述复合绝缘子湿润过程的数学模型并针对两种初始憎水性状态对比研究了不同温度情况下的湿润特性。结果发现:低温雾中复合绝缘子的湿润模型是由湿润、过渡、烘干等过程重复组成,而室温下雾的强冷凝作用导致表面持续湿润并放电,湿润或烘干过程并不明显,使得湿润模型可仅存在过渡过程;此外,憎水性有效地抑制了泄漏电流工频分量的幅值,即有效地减轻了污层的湿润程度并延缓了达到第一次饱和湿润的时间,最终使得耐受电压(耐受时间)要高于(长于)丧失憎水性的情况。     

Daily generation scheduling optimization with transmissionconstraints: a new class of algorithms

The authors describe a novel class of algorithm dealing with the daily generation scheduling (DGS) problem. These algorithms have been designed by adding artificial constraints to the original optimization problem; handling these artificial constraints by using a dual approach; using an augmented Lagrangian technique rather than a standard Lagrangian relaxation technique; and applying the auxiliary problem principle which can cope with the nonseparable terms introduced by the augmented Lagrangian. To deal with the DGS optimization problem these algorithms are shown to be more effective than classical ones. They are well suited to solve this DGS problem taking into account transmission constraints