Combining prospective motion correction and distortion correction for EPI: towards a comprehensive correction of motion and susceptibility-induced artifacts

Object  

State-of-the-art MR techniques that rely on echo planar imaging (EPI), such as real-time fMRI, are limited in their applicability by both subject motion and B₀ field inhomogeneities. The goal of this work is to demonstrate that in principle it is possible to accurately predict the B₀ field inhomogeneities that occur during echo planar imaging in the presence of large scale head motion and apply this knowledge for distortion correction.     

超超临界燃煤发电技术是我国目前发展洁净煤发电技术的优先选择

超超临界燃煤发电技术是目前世界上成熟、先进、高效的发电技术。通过对几种主要的洁净煤发电技术的比较，配有污染物排放控制技术的超超临界燃煤发电机组在效率、容量、可靠性、设备投资及环保等方面都具有一定的优势。分析火电行业存在的主要问题，认为超超临界燃煤发电技术是我国目前发展洁净煤发电技术的优先选择。根据电力行业、发电设备制造业及相关行业的现有基础，指出我国已具备了发展超超临界燃煤发电技术的条件。     

计及安全约束和网损修正的节能发电调度方法及实践

节能发电调度正在国内试点,尚无统一的模式,也缺乏实用化的支持软件.提出了计及安全约束的发电机组煤耗和网损折算煤耗综合最小的目标函数,并应用改进内点法求解目标函数.据此开发了生成节能发电调度计划的软件支持系统,能实现BP(A)数据自动导人、外网等值、机组爬坡约束设定、机组多种运行方式设定等多种功能,并能自动生成96点发电计划.在某实际电网运行实践表明,该方法能有效减少综合煤耗,可产生显著的节能减排效益.     

Simulation and field tests of the black start of a large coal-firedgenerating station utilizing small remote hydro generation

A method for utilizing remote hydro generation to restart a major coal-fired generating station is described. The author documents a comprehensive black start project. It includes considerations for a black start project, details of an analytical study, identification of critical factors, development and implementation of an actual black start test, comparison of field tests with the simulation results, and the required system modifications identified during the project     

SEGEM: a simulation approach for electric generation management

We present a modeling framework for a robust simulation of multiperiod hydrothermal power management and energy trading under uncertainty in generators availability, fuel procurement, transport and stock costs, exogenous water inflow at river basins and energy demand per subperiod at each time period of a given planning horizon. A deterministic treatment of the problem provides unsatisfactory results for medium term (1-2 years) planning horizon. We use a 2-stage scenario analysis based on a partial recourse approach, where the generation decision policy can be implemented for a given set of initial periods and the solution for the other periods does not need to be anticipated and, then, it depends on the scenario to occur. We have used an augmented Lagrangean decomposition scheme by dualizing the coupling constraints splitting control variables (fuel stock and stored water) for the last implementable period. We present computational results including different simulations of a Spanish generation subsystem composed of 87 thermal generators, 57 hydro plants and reservoirs, 7 fuel types and 5 time periods. 160 scenarios are simultaneously considered     

发输电系统可靠性分析中最优切负荷模型

电力系统可靠性分析的过程中系统状态分析环节最为核心,也最为费时,尤其是在状态抽样中用到枚举法或者蒙特卡洛模拟法时,需要进行大量的系统状态分析。本文提出切负荷量最小兼顾负荷重要度和区域就近削减负荷原则来进行负荷削减。重要度原则体现在削减负荷时按负荷级别进行削减,区域就近原则使得切负荷点不再在全系统范围内搜寻,大大减少了计算时间。通过IEEE-RTS79可靠性测试系统的计算结果可知,该法在减少计算时间方面有明显的优势,切负荷量也更切合实际情况。     

SIP协议是智能电网通信的一个明智选择

智能电网的开发和建设在美国、中国以及世界其他国家正在积极地推进,而通信作为智能电网建设的一个组成部分,将发挥十分重要的作用。文章介绍了基于互联网协议（IP协议）的会话发起协议（Session Initiation Protocol-SIP）的功能和作用,按照智能电网架构所需要的开放性、标准化和互操作性的要求,SIP协议可以满足智能电网对通信的所有要求,因此,在智能电网通信中,选择SIP协议是一个非常明智之举。     

Strategic generation with conjectured transmission price responses in a mixed transmission pricing system-part II: application

The conjectured transmission price response model presented in the first of this two-paper series considers the expectations of oligopolistic generators regarding how demands for transmission services affect the prices of those services. Here, the model is applied to northwest Europe, simulating a mixed transmission pricing system including export fees, a path-based auction system for between-country interfaces, and implicit congestion-based pricing of internal country constraints. The path-based system does not give credit for counterflows when calculating export capability. The application shows that this no-netting policy can exacerbate the economic inefficiencies caused by oligopolistic pricing by generators. The application also illustrates the effects of different generator conjectures regarding rival supply responses and transmission prices. If generators anticipate that their increased demand for transmission services will increase transmission prices, then competitive intensity diminishes and energy prices rise. In the example here, the effect of this anticipation is to double the price increase that results from oligopolistic (Cournot) competition among generators.     

Seismic behavior of flexible conductors connecting substation equipment-part II: shake table tests

Due to failures of interconnected equipment in recent earthquakes, it is suspected that the seismic interaction of the flexible conductors with the equipment during a strong ground motion could cause additional unpredicted forces, resulting in damage or collapse of the equipment they interconnect. This paper presents the results of an investigation into the dynamic behavior of flexible conductors by performing several shake table tests on a class of flexible conductors and the relevant 500-kV interconnected equipment used in substations throughout the province of British Columbia in Canada. The test specimen consisted of large scale models of the equipment items and the actual size flexible conductors. The shake table input records were synthetic earthquakes generated to fit an IEEE prescribed response spectrum. This investigation showed that the dynamic effect of flexible conductors must be considered when evaluating the seismic capacity of interconnected equipment.     

Developing a database for a reliability, availability, andmaintainability improvement program for an industrial plant orcommercial building

It is argued that database development is a critical part of the design of any industrial reliability, availability, and maintainability (RAM) program. A time-tested process for assembling a sound RAM database is outlined. Its applicability to electrical systems is obvious, but it can also be used successfully in improving the reliability of the various other types of systems in an industrial facility, commercial building, or health care facility     

Fuzzy support for serodiagnosis: the ONSET program

ONSET derives its diagnosis from the combined evidence of contemporaneous and successive findings, which is in accordance with the behaviour of a clinician. Although it does not increase the diagnostic capabilities in principle, i.e., it cannot perform better than an expert reasoning on the basis of the same knowledge, computational power can be exploited to perform the matches and combine the results with greater precision, resolution, reliability, and transparency. Fundamental improvements of diagnosis, however, can only be expected from better serological tests or increased testing frequency. ONSET relies on domain knowledge explicated in a non-verbalized, analytical form. Knowledge representation-although mathematical-is intuitively clear and easy to conceive, making it equally accessible to both man and machine, and hence subject to objective evaluation and criticism     

Design, implementation and clinical tests of a wire-based robot for neurorehabilitation.

This paper presents the development of and clinical tests on NeReBot (NEuroREhabilitation roBOT): a three degrees-of-freedom (DoF), wire-driven robot for poststroke upper-limb rehabilitation. Basically, the robot consists of a set of three wires independently driven by three electric motors. The wires are connected to the patient's upper limb by means of a splint and are supported by a transportable frame, located above the patient. By controlling wire length, rehabilitation treatment (based on the passive or active-assistive spatial motion of the limb) can be delivered over a wide working space. The arm trajectory is set by the therapist through a very simple teaching-by-showing procedure, enabling most common "hands on" therapy exercises to be reproduced by the robot. Compared to other rehabilitation robots, NeReBot offers the advantages of a low-cost mechanical structure, intrinsically safe treatment thanks to the use of wires, high acceptability by the patient, who does not feel constrained by an "industrial-like" robot, transportability (it can be easily placed aside a hospital bed and/or a wheelchair), and a good trade-off between low number of DoF and spatial performance. These features and the very encouraging results of the first clinical trials make the NeReBot a good candidate for adoption in the rehabilitation treatment of subacute stroke survivors. Clinical trials were performed with a 12-patient experimental group and a 12-patient control group. Resulted that the patients who received robotic therapy in addition to conventional therapy showed greater reductions in motor impairment (in terms of Medical Research Council score, the upper limb subsection of the Fugl-Meyer score, and the Motor Status Score) and improvements in functional abilities (as measured by the Functional Independence Measure and its motor component). No adverse effects occurred and the robotic approach was very well accepted. According to these results, the NeReBot therapy may efficaciously complement standard poststroke multidisciplinary rehabilitation and offer novel therapeutic strategies for neurological rehabilitation.     

Towards a global control strategy for induction motor: Speed regulation,flux optimization and power factor correction

A great deal of interest has been paid to induction machine control over the last years. However, most previous works have focused on the speed/flux/torque regulation supposing the machine magnetic circuit to be linear and ignoring the machine power conversion equipments. The point is that speed regulation cannot be ensured in optimal efficiency conditions, for a wide range of speed-set-point and load torque, unless the magnetic circuit nonlinearity is explicitly accounted for in the motor model. On the other hand, the negligence of the power conversion equipments makes it impossible to deal properly with the harmonic pollution issue due to ‘motor – power supply grid’ interaction. This paper presents a theoretical framework for a global control strategy of the induction machine and related power equipments. The proposed strategy involves a multi-loop nonlinear adaptive controller designed to meet the three main control objectives, i.e. tight speed regulation for a wide range speed-reference variation, flux optimization for energy consumption and power factor correction (PFC). Tools from the averaging theory are resorted to formally describe the control performances.     

电子商务——企业最佳的选择

随着科学技术的不断创新和发展，全球经济正在进入信息时代，而信息社会的最大特征就是网络化和自动化，电子商务作为信息技术的产物，是构成现代网络经济的重要组成部分。它的蓬勃发展给全球经济带来了巨大的变革，并成为推动经济增长的主要动力，电子商务作为企业的一种商务活动，它不仅仅是电子贸易，同时也包含了企业、政府部门以及各种机构的信息交流。通过电子商务企业将超越时空界限、拓展市场、取得更大的经济效益。     

Biomedical engineering: the career of choice

In the author's opinion, the biomedical engineer is ideally trained to work at the intersection of science, medicine, and mathematics to solve biological and medical problems, so that a university degree in biomedical engineering will prepare you for many professions. The following questions are explored: What do biomedical engineers do? How do biomedical engineers differ from other engineers? How much education does a biomedical engineer require? How can a high school education prepare me for studies in biomedical engineering? What types of university courses will prepare me to be a biomedical engineer? What kind of practical experience can I expect to gain while training? Where do I get more information?.     

PCSIGV: a student-oriented program for calculating the parasitic capacitances for single-level interconnections on GaAs-based VLSI

A microcomputer-efficient algorithm to study the parasitic capacitances associated with high-density single-level interconnections on GaAs-based VLSI is presented and a student-oriented program called PCSIGV is discussed. The algorithm uses the method of moments in conjunction with a Green's function appropriate to the geometry of the interconnections. Results include the fringing fields as well as the effects of shielding due to the presence of the neighboring interconnection lines. PCSIGV has been used to study the dependence of the ground and coupling interconnections capacitances on various interconnection parameters.<>     

Development of a damping analysis program for multi-generator powersystems

A numerical damping analysis program (DAMP), based upon the frequency scanning method, for application to multi-generator power systems has been developed. This program permits the determination of electrical and mechanical torsional damping at arbitrary frequencies with respect to the individual generator under consideration within such a multi-machine system. Therefore, this allows the quantitative frequency domain analysis of power swing and torsional oscillation with due consideration for the effects of mutual interference among the generators. In this paper, first, the basic algorithm, modeling method, and validity of the new program are indicated. Next, the effectiveness of the program is demonstrated through SSR and other types of analyses for multi-machine systems     

区域电网内多输电断面有功协同控制策略在线生成方法

以多个断面功率不越极限为控制目标、调整量最小为优化目标,基于直流潮流法的断面有功灵敏度建立求解多断面有功协同控制策略的非线性规划模型;为提高模型求解的可靠性和速度,引入辅助变量将该模型转化为线性规划模型;利用交流潮流法进行安全校核,以检验策略的有效性。从计算启动、建模求解及安全校核三方面设计闭环的在线滚动计算流程;提出适用于各种网络拓扑变化的节点电纳矩阵及其逆矩阵的滚动修正方法;采用可调元件有功调节限值修正策略剔除无效的调整措施。案例结果验证了所提方法的有效性;且每轮计算耗时在2 min以内,表明所提方法的计算速度满足实时调度要求。