Algorithms of a digital automatic system for tension and loop control in a wide-strip hot-rolling mill

The manufacture of hot-rolled strips 0.8–1.5 mm in thickness as a final product of metallurgical works necessitates strict requirements for gage interference of the strip, namely, with a tolerance of ±5%. The tension variation for such a range of rolled products significantly affects the gage interference. Consideration is given to corrected algorithms for calculation of the torque of an electric drive for a loop lifter and the definition of the angle of the loop-lifter ascent and the control algorithm for the loop size in the interstand area, which are realized in a digital automatic system for the tension and loop control in a 2500 wide-strip hot-rolling mill. The pilot study proved that the implementation of advanced algorithms and the developed system for interactive tension and thickness control made it possible to meet the increased gage interference requirements.     

On-axis field approximations for a (semi-)spheroid in a uniform field

I have recently been analyzing various problems in the area of breakdown of solids and gases using a highly prolate, conducting spheroid in a uniform electric field as a model for a breakdown channel. The electric field distribution for a prolate spheroid in a uniform field can be solved in spheroidal hyperbolic coordinates. The solution is exact for a conducting prolate spheroid in an infinite, uniform field or a semiprolate conducting spheroid on the surface of a plane electrode with the opposite electrode infinitely far away. In working with these equations, I have developed several approximations, including a very simple equation for the field at the tip of the spheroid and an equation for the field on axis of the spheroid, which may be useful to others.     

A brief review of hardware for catheter tracking in magnetic resonance imaging.

Magnetic resonance imaging (MRI) has traditionally been used exclusively in a role for patient diagnosis. However, it is unlikely that this role is sufficient for its continued prominence in medical imaging. Instead, the more ambitious role in diagnosis and also therapy/intervention will occur as demand for minimally invasive procedures increases. Fortunately, with recent improvement in technical specifications and creative pulse sequence design, MRI systems can now provide high quality near-real-time images that facilitate a variety of image-guided procedures, many based around delivery via catheters. While X-ray opacity is not available as a means for detecting the progression of the catheter in MRI systems today, a variety of novel hardware devices have been designed and used for MRI catheter tracking. This report provides a brief review of some fundamental methods for catheter tracking in MRI.     

Probabilistic Lane Tracking in Difficult Road Scenarios Using Stereovision

Accurate and robust lane results are of great significance in any driving-assistance system. To achieve robustness and accuracy in difficult scenarios, probabilistic estimation techniques are needed to compensate for the errors in the detection of lane-delimiting features. This paper presents a solution for lane estimation in difficult scenarios based on the particle-filtering framework. The solution employs a novel technique for pitch detection based on the fusion of two stereovision-based cues, a novel method for particle measurement and weighing using multiple lane-delimiting cues extracted by grayscale and stereo data processing, and a novel method for deciding upon the validity of the lane-estimation results. Initialization samples are used for uniform handling of the road discontinuities, eliminating the need for explicit track initialization. The resulting solution has proven to be a reliable and fast lane detector for difficult scenarios.      

考虑风险约束的发电公司报价策略研究

针对采用分段报价策略和按发电公司报价结算的电力市场，提出了构造计及风险约束的发电公司最优报价策略的模型框架。在假设所研究的发电公司对其竞争对手的报价策略概率分布已知的前提下，首先提出了计算采用某种报价策略时的期望利润和相应风险的方法，然后根据发电公司自身的风险偏好，定义了在最大化利润和最小化风险这两个目标间折衷的效用函数，发展了使报价策略所产生的效用最大化的最优报价策略模型和以遗传算法为基础的求解方法。最后用一个有5个发电公司参与的电力市场为例来说明所提出的方法的基本特征。     

Predicting the energy-supply parameters for a transportation process based on multifactor models

Results are presented for the construction of a model of an energy-supply parameter characteristic for the transportation process, “electric-energy consumption for traction (plan),” based on the identification thereof with actual production and economic parameters by the example of one of the branches of JSC Russian Railways. The research was carried out based on a database created for monthly actual values over a long period, from 2007 to 2016. A methodology and results are presented for statistical studies of the parameter “electric-energy consumption for traction (plan)” in conjunction with 20 parameters, including “sectoral speed,” “average weight of the train,” “transportation costs.” The methodology involves choosing the factors for a multifactorial model and elimination of the consequences of multicollinearity based on the results of cluster analysis and constructed dendrograms. Variants are presented for the construction of multifactorial models to predict and manage the parameter of “electric-energy consumption for traction (plan)” for control and risk-management tasks. A variant of construction of a multifactorial model for predicting and control of the parameter “electric-energy consumption for traction (plan)” for control tasks and risk-management is given. As a mathematical tool for constructing the multifactorial models, a technique of linear regression equations has been used. The construction of dendrograms and obtaining the regression equation coefficients have been carried out using the Statistica software package. Using the multifactorial model results in improvement in the predictive accuracy of the “electric-energy consumption for traction (plan)” parameter measured with a MAPE estimate, from a 15% level to a level better than 6%.     

Partial vacuum breakdown characteristics of helium at 20 kHz for inhomogeneous field gap

In general, power devices and systems operating in vacuum or space environment are more susceptible to partial discharges, corona, or volume discharges due to the partial vacuum conditions. Additionally, high frequency operation of a power system is a contributing factor in lowering the breakdown voltage of insulation. In this paper we present our studies on the breakdown characteristics of helium operating in DC and 20 kHz AC field in partial vacuum, for a point-to-point and point-to-plane electrode configurations. Breakdown voltage as a function of pressure in the range of 27 to 400 Pa (0.2 to 3 torr) for both the DC and 20 kHz AC cases is presented. Voltage and current waveforms along with the optical emission waveform of the breakdown events are also presented. A variable DC power supply for DC and an in-house built variable DC-offset-AC power supply for the high frequency breakdown experiments are used. A high voltage probe and a Pearson current sensor are used for the voltage and current detection, and a photo-multiplier-tube with a digital pico-ammeter and a video camera are used for the optical signal detection of this set-up. The breakdown voltage as a function of pressure for both the AC and DC experiments, along with voltage breakdown waveforms for both electrodes are presented.     

The P1605 and P1606 working group report

This article presents a history to date for P1605, a guide for comparison of existing installation requirements for electrical distribution and utilization equipment in North America and Europe, and P1606, a guide for comparison of existing electrical safety standards for employee workplace in North America and Europe. The comparison will address requirements contained in North American standards (OHSA, NFPA70E) and European standards EN 50110 highlighting similarities and differences in these standards.     

An Initial Model for Control of a Tandem Hot Metal Strip Rolling Process

The tandem rolling of hot metal strip presents a significant control challenge because of nonlinearities and process complexities. The challenge is heightened by an extremely hostile environment that precludes the location of sensors to measure process variables that are important for control. In addition, it is essential that the controller structure allows for a high degree of physical intuition in the design process and provides for simplicity of tuning during commissioning. Based on our previous work using a state-dependent Riccati equation (SDRE) technique for control of the tandem cold rolling process, it is considered that a similar method might also be useful as a basis for the development of a control technique for tandem hot strip rolling. For the hot rolling process, the development of a process model in a form that is suitable for use with a SDRE-based method is a significant and challenging task. This paper describes our work to develop an initial model for this process. Based on simulation results, it is determined that this initial model has the potential to be the basis for the development of the complete nonlinear model that can be used for development of a viable control method which offers the likelihood for improvement in the control of the hot metal rolling process.      

Salt fog testing of polymer housed surge arresters

This paper deals with the evaluation of the insulation design of polymer housed surge arresters for distribution lines. Five commercial designs were tested in a salt fog chamber for 9 cycles using a cycle consisting of 120 hours of salt fog that was followed by a 48 hour rest period for a total of 1280 hours of salt fog. In these tests, the specification for the 1000-hour salt fog test in IEC 1109 for composite insulators was used as a guide. The results demonstrate that a comprehensive evaluation of the external and internal insulation design of polymer housed surge arresters can be obtained by performing a salt fog test, and as such, the test can be considered as a useful design test. Suggestions for improvements in the insulation design of all polymer housed surge arresters evaluated are given in the paper     

Modern methods and means for nondestructive testing of the quality of power semiconductor devices

Modern methods and means for designing devices for nondestructive testing of parameters of power semiconductor devices are described. A new method for determining the junction–case thermal resistance from the transition function of a thermosensitive parameter is presented. The operating principle of a specialized digital system for controlling and displaying the vibration frequency and linear accelerations during testing of the absence of freely moving particles, short circuits, and breaks in the circuits of electrodes is presented. The function of digital filtering of a signal that is formed by the sensor–accelerometer board is considered. A new method for the formation of a single shock-current pulse is described that is based on the use of the principle of a discrete superposition of charges in the electric circuit of the secondary winding of a power pulse transformer. The principle of the formation of a test voltage pulse in a test-pulse generator of the software–hardware complex for the automatic assignment of grades, which is based on the implementation of the pulse-amplitude modulation of pulse parameters in a galvanically isolated power control loop, is presented.     

Simultaneous solution of control system equations in EMTP

The existing approach for solving control systems in the Electromagnetics Transients Program is to insert one-time-step delays for breaking feedback loops when one or more nonlinear functions is encountered. Although this approach may remain acceptable for several well-behaved cases, it provides a nonsimultaneous solution for a nonlinear system. Fast varying components may create instabilities in such a solution and/or simply end up in a wrong operating region. In some cases, it imposes severe limitations on the integration time step for minimizing delays. This paper presents a new Jacobian matrix-based formulation for eliminating numerical delays in the solution of control system equations.     

分析能耗的边际(火用)成本模型

为实现整个能量系统在偏离最佳经济工况时的经济性分析和诊断，及对于系统中某单元或设备的设计优化和经济运行，以热经济学理论与方法建立边际Yong日成本能耗分析模型，按照产品形成过程去追踪燃料消耗量，并便于计算庞大系统复杂参数变化的能损分布问题，为机组节能潜力的诊断提供决策依据。通过计算机编程对200MW机组进行了求解，其结果表明：机组参数偏离设计工况时，不同参数引起的能耗增加不同，且符合自然累加原则，并进行了系统仿真模拟，验证了该模型的可靠性。     

Modulation transfer functions for quality assurance of mammographicsystems

A “quality relative index” for expressing radiographic system quality is described. The purpose of this investigation is to quantify MTF dependencies in order to establish criteria for assessing actual image quality in terms of relative sharpness, depending on the orientation and positioning of the object along the radiation field. A procedure is proposed in which numerical values are assigned to the MTF curves in order to inter-relate MTFs for different orientations in the field center for a given radiographic system. This procedure has been named the MTF Quality Relative Index, with a single number that defines how better or worse an MTF curve is for a given direction of a system in comparison to a different direction. From an equation using parameters extracted from the curves in the center, the procedure is extended to the whole field through analogy to the evaluation of 2-D MTFs calculated for the respective locations     

A generalized approach for the steady-state analysis of resonantinverters

A generalized approach is presented for the steady-state analysis of resonant inverters which leads to the selection of an optimum scheme for a particular application. Six load-commutation schemes are combined into a single commutation scheme, referred to as a generalized load-commutation circuit, and the steady-state analysis for the circuit with RL load is presented using a Fourier series approach in the continuous-current mode. The equations for different load-commutation circuits are obtained as the particular cases of the generalized configuration. This type of unified approach simplifies the method of analysis for different commutation schemes and eliminates the need for the separate analysis of different schemes. Also, in a computer program, the results for a particular configuration can be obtained simply by opening or shorting the nonrequired commutating components of the generalized scheme. The method of analysis is used to select resonant inverter schemes with resistive load, based on certain constraints. Experimental results are presented for the selected schemes to support the theory     

Silicon oxynitride planar waveguiding structures for application inoptical communication

The refractive index of silicon oxynitride (SiON), a widely used material for integrated optics devices, can be chosen in a wide range between 1.45-2.0. We describe how the consequent large design freedom can be exploited on the one hand for a “standard” polarization independent optical channel waveguide having a favorable tradeoff between efficient fiberchip coupling and small bend radii (compact devices) and on the other hand for special-purpose and hybrid components where the refractive index should be finely adjusted for obtaining the desired functionality. We illustrate the applicability of SiON by describing a few devices for optical filtering in a new architecture for wavelength multiplexing, modulation, polarization splitting and second-harmonic generation     

Power Supplies for Electronic High-Voltage Measuring-Current Transformers

A power supply for electronic high-voltage measuring-current transformers with extraction of energy from the measured current that flows through a high-voltage line has been considered. A magnetic core of the supply transformer from the windings of which the necessary power is extracted is mounted on the line for this purpose. When the line current changes over a wide range, the supply transformer should have a quickly saturated magnetic core. It has been shown that, to reduce the losses and decrease the loading of the elements of a power-supply circuit in a wide current range, a ballast load should be introduced in the circuit of a secondary winding. Three variants of the ballast load have been compared: resistive, capacitive, and in the form of a transistor-current limiter. The results of simulations in the VisSim software have been considered for all three variants, as well as for the case of absence of a ballast load in the power-supply circuit. The simulations were carried out for the lowest and highest measured currents, as well as for the line short-circuit mode. The results of simulations have shown the advantages of a power supply based on a saturated transformer with a transistor-current limiter. A variant of a circuit of a transistor-current limiter has been suggested.     

基于物元可拓的输电线路山火风险评估模型

为了解决现有的输电线路山火风险评估方法中风险指标单一、过于依赖主观经验等问题,提出了一种基于物元可拓的输电线路山火风险评估模型。首先,收集对山火发生概率产生影响的人为、地理、气候以及线路4大类共15个风险指标,构建了输电线路山火灾害风险评估指标体系。然后,将模糊层次分析法和熵权法相结合,形成主观赋值权重与客观计算权重结合的评估指标组合权重。并在此基础上建立物元可拓评估模型,计算风险指标关联度,基于关联度大小确定最终输电线路山火风险等级。最后,通过对南方某省份输电线路工程进行实例分析,对其山火灾害风险等级进行综合评估,为运维管理人员开展差异化的山火防治工作提供了依据。     

The Use of Graded Nets in Computer Modeling of Corotron Fields

The use of computer modeling with finite-difference techniques to solve for electrostatic fields by successive overrelaxation in regions where no exact analytic solution exists is well documented. However, for irregular Dirchlet boundary curves in two dimensions, which do not contain the nodes of a regular net, various interpolation schemes must be used. It is shown in this paper that these interpolation schemes introduce appreciable error into the solution for a boundary curve with a small radius of curvature, such as is found in the center of a corotron. An alternate technique is described which uses successive graded nets in the immediate region of the boundary. The validity of the method is confirmed in the case of a small wire with an applied voltage concentric with a grounded conducting cylinder, where an analytical solution is then possible. The method is then used for the solution of the Laplacian fields for a corotron having typical dimensions.