A framework for constraining image SNR loss due to MR raw data compression

Magnetic Resonance Materials in Physics, Biology and Medicine - Computationally intensive image reconstruction algorithms can be used online during MRI exams by streaming data to remote...     

A framework for the specification of SCADA data links

SCADA system overall performance is dependent on satisfactory performance of the integral data communication links. Therefore a specification of the required data link performance is required as part of the system specification. But what should the data link specification include? The specification of data rate alone is shown to be insufficient to guarantee performance under all operating conditions. To determine the additional attributes that must be specified, the sensitivity of SCADA performance to the set of data link attributes is analysed by computer simulation. From the results of the simulation a subset of significant data link attributes is identified. This is the desired data link specification framework     

A computationally efficient MOV model for series compensationstudies

The authors describe a computationally efficient model for metal oxide varistors (MOVs) suitable for use in simulation studies of series compensated lines. It can also be used in simulators running EMTP type solutions in real-time since it does not rely on an iterative technique for its implementation. The EMTP program on which this work is based is the version written by Manitoba Hydro and is called EMTDC. The line on which the studies have primarily been based is the 500 kV line from the Dorsey converter station north of Winnipeg to the Forbes substation in Minnesota. The source structure has not been represented in great detail but is adequate for examining the behavior of the MOVs. In addition, the proposed model is inserted in a simulation of a previously published study and shown to give good agreement     

A framework for UMTS air interface analysis

An integrated approach is presented for uplink and downlink air interface capacity evaluation and traffic analysis for the multiservice Universal Mobile Telecommunications System (UMTS). Within this framework the effects of both soft handoff (SHO) and fast power control (FPC) are considered. The canonical capacity of any given service, defined as the maximum number of concurrent users of that service, is derived; and the network total load is described as a function of this parameter and the number of concurrent users. The concept of virtual slots is defined within this integrated framework to obtain an accurate estimate for the blocking probability of each service type. A number of case studies are also presented to compare the results of utilizing the proposed framework with the results of network simulation. This comparison demonstrates the accuracy and usefulness of the proposed approach for network design and dimensioning.     

A basic framework for sub-transmission system health analysis

The reliability of supply in sub-transmission systems is usually quantified in terms of two sets of indices, the individual supply/load point indices (average failure rate, average outage duration and average annual unavailability) and the system performance indices (SAIFI, SAIDI, CAIDI, ASUI, ASAI, etc.). These probabilistic indices are very useful not only for assessing the severity of system failures in future reliability predictions but also in assessing the system’s past performance. Many utilities, however, continue to use deterministic methods (rule-of-thumb methods) to assess the reliability of their systems. This paper presents a method designated as system well-being analysis, which in addition to the conventional probabilistic risk index of supply point unavailability, also incorporates the specified deterministic criteria in defining additional system healthy and marginal states. The proposed method is illustrated in this paper to calculate the well-being indices of electric sub-transmission systems. The proposed technique, which can be used to evaluate the adequacy of sub-transmission systems, is applied in this paper to a small but comprehensive test system to show the effects of some pertinent factors and deterministic criteria on the system well-being indices.     

A basic framework for generating system operating health analysis

A probabilistic technique is presented in this paper to assess the operating reserve requirements in a system. In this approach, the generation system is classified into different system operating states. This technique combines deterministic with probabilistic indices to monitor the well-being. The system well-being as designated by deterministic criteria are identified as being healthy, marginal and at risk. A risk index designated as the generating system operating state risk (GSOSR) is defined in this paper as the probability of residing in an undesirable operating state. Technique together with the effect on the GSOSR and the system operating state probabilities of factors such as lead time, system peak load, load forecast uncertainty and generating unit derated states are illustrated by application to the IEEE-RTS (reliability test system)     

电力数据网络柔性安全体系

针对电力系统引进的安全工具不能根据系统安全状况灵活调整安全配置，系统各部间也不进行通信协调工作的问题，设计了基于简单网络管理协议（SNMP）的电力数据网络柔性安全体系。它通过管理器（Managers)集中管理网络中的传感器（Sensors)和动作器（Operators)。传感器负责检测安全险情，并将检测结果报告给管理器，管理器则根据检测结果指挥动作器进行相应的安全策略调整。     

Grid-free interactive and automated data processing for MR chemical shift imaging data

Purpose  

Today’s available chemical shift imaging (CSI) analysis tools are based on Fourier transform of the entire data set prior to interactive display. This strategy is associated with limitations particularly when arbitrary voxel positions within a 3D spatial volume are needed by the user. In this work, we propose and demonstrate a processing-resource-efficient alternative strategy for both interactive and automated CSI data processing up to three spatial dimensions.     

Integrated framework for dynamic security analysis

Ever increasing power transfers over long distances have pushed the operating conditions of the power systems closer to the stability limits. The various special control schemes to deal with the resulting security problems have allowed the operation of the power systems even closer to the security limits of the system. Transient stability simulation is an important tool used extensively in planning and operating power systems which face such stressed conditions. This paper describes an integrated framework for dynamic security analysis in both the on-line and the off-line modes. In the on-line mode, the framework allows for the use of efficient techniques for the pre-selection, screening and ranking of contingencies and the calculation of relevant operating limits. In the off-line mode, this framework can help the operations planner by: providing a friendly graphical user interface; guiding a systematic progression in the decision making process; preparing relevant combinations of available options and adverse system operating conditions; minimizing inadvertant omissions; performing routine data manipulation; archiving and retrieving information; checking the input data for completeness, consistency and reasonability; and organizing the output results from various cases. The computational capabilities of modern workstations along with innovative software technologies have been exploited to develop a software system that can capture and apply the knowledge of operations planners so as to minimize or eliminate the tedious tasks associated with the system operational planning process     

智能配用电大数据存储架构设计

针对智能配用电数据海量、高维度、多源异构等特点,提出一种大数据存储的三层管理框架设计方案。首先,对智能配用电数据组成进行分类划分。然后,提出智能配用电数据存储的资源层、元数据层和实际数据层的三层管理框架,在资源管理层,应用虚拟化技术、负载均衡和资源调度完成对物理资源的管理;在元数据管理层,使用数据预处理技术对智能配用电的元数据进行分类,采用中间件技术完成XML元数据仓库管理;在实际数据管理层,利用NoSQL技术,通过Map和Reduce的有效结合,完成海量数据的分层分区快速存储。最后,在实验室环境下对该设计方案进行初步的应用,验证了所设计方案能够对结构化、半结构化和非结构化数据进行统一存储,可为智能配用电大数据技术的应用提供基础支撑作用。     

基于SpringBatch框架的数据批量处理

通常企业决策分析系统需要对关键业务信息进行批处理操作,而这些业务的批处理操作是在没有用户进行交互的情况下对大量复杂的信息进行自动处理.为了解决批处理数据操作效率低下的问题,本文在对SpringBatch框架进行深入的研究和分析的基础上,选用SpringBatch框架,开源作业调度库Quartz以及关系型数据库MySQL和非关系型数据库Cassandra,设计并实现了高效批处理的决策分析系统.同时本文还对该系统进行相关性能测试,测试结果证明使用SpringBatch框架的决策分析系统批数据处理能力得到了极大的提升.     

A unifying framework for the analysis of proportionate NLMS algorithms

Despite being a de facto standard in sparse adaptive filtering, the two most important members of the class of proportionate normalised least mean square (PNLMS) algorithms are introduced empirically. Our aim is to provide a unifying framework for the derivation of PNLMS algorithms and their variants with an adaptive step‐size. These include algorithms with gradient adaptive learning rates and algorithms with adaptive regularisation parameters. Convergence analysis is provided for the proportionate least mean square (PLMS) algorithm in both the mean and mean square sense and bounds on its parameters are derived. An alternative, more insightful approach to the convergence analysis is also presented and is shown to provide an estimate of the optimal step‐size of the PLMS. Incorporating the so obtained step‐size into the PLMS gives the standard PNLMS together with a unified framework for introducing other adaptive learning rates. Simulations on benchmark sparse impulse responses support the approach. Copyright © 2014 John Wiley & Sons, Ltd.     

基于区块链的用能数据完整性保护框架

终端设备的分布式拓扑结构和节点有限的计算资源给区块链和用能信息采集系统集成带来很大阻碍,为此,提出基于区块链的多层互连数据保护框架(HBDF),用于能源互联网下的用能数据安全采集.HBDF以分散方式对终端设备进行身份认证来克服单点故障问题以及提高系统的可扩展性.利用基于截断式哈希消息认证码(HMAC)的承诺方案构建轻量级数据完整性验证方案,该方案利用反向哈希链表对验证密钥进行更新来减轻受限节点的计算负担.对框架安全性的分析表明,其可对通信实体和内容进行有效认证.实验验证了该框架的可行性.     

A novel approach to computationally efficient algorithms for transmission loss and line flow formulations

This paper presents a novel approach to powerful, effective and computationally efficient algorithms for formulation and evaluation of transmission loss and line flow through efficient loss coefficients and distribution factors, respectively which are uniquely suitable for real term application. These loss coefficients and distribution factors are generated extremely elegantly and efficiently from the hidden treasures of an available load flow solution with trivial computational burden. Results on few IEEE Test systems are extremely exciting which reveal that the loss coefficients evaluated at the normal operating conditions are quite robust and for all practical purposes need not be re-evaluated for wide changes in system operating conditions for evaluation of transmission loss or economic load dispatch solution.     

A unified framework for it security - analysis - [IT security]

IN IT security, the nature of the threat landscape is ever changing, ever volatile. Incidents of cyber crime are rising steadily, as is the cost and complexity of protecting enterprise systems and information from hackers, viruses, and other strains of malware. Cases of phishing and identity theft are also escalating. Social networking sites have, arguably, introduced additional vulnerabilities into the picture, as has the threat of criminal activity from imposters posing as legitimate users.     

基于spark框架的能源互联网电力能源大数据清洗模型

对能源大数据清洗可提高能源大数据质量的正确性、完整性、一致性、可靠性。针对能源大数据清洗过程中的提取统一异常检测模式困难、异常数据修正连续性及准确性低下等问题,提出了一种基于Spark框架的能源能源大数据清洗模型。首先基于改进CURE聚类算法获取正常簇;其次,实现了正常簇的边界样本获取方法,并设计了基于边界样本的异常识别算法;最后通过指数加权移动平均数实现了异常数据修正。通过对某风电场风力发电监测数据进行了数据清洗实验分析,验证了清洗模型的高效性、准确性。     

Design and analysis framework for linear permanent-magnet machines

This paper presents a design and analysis framework for the general class of permanent magnet electric machines. In the authors' analysis, surface-mounted linear motors consisting of permanent magnets and ironless current-carrying coils are treated in a uniform way via the magnetic vector potential. This analysis is developed to design novel linear magnetic levitators for driving precision motion control stages such as those used in wafer steppers. For one such motor structure, they give analytical formulae for its magnetic field, force, flux linkage, inductance of the winding, and back electromotive force. They provide experimental results with a six degree-of-freedom magnetic levitator. These results are in good agreement with analytical estimations. The levitator uses a permanent-magnet Halbach array in order to improve its power efficiency. By analogy, there also exists an electromagnetic dual of the Halbach array. One such dual utilizes a triangular winding pattern in order to achieve a primarily single-sided magnetic field     

A PC-based workstation for processing and analysis of MRI data

The present work demonstrates that a low cost, flexible and user-friendly workstation for the MRI laboratory can be implemented by using a personal computer and public-domain software. The workstation is based on a Pentium^® personal computer, operating under the Linux operative system, and uses the software Khoros^® (Khoral Research, Albuquerque, NM). This software is a general purpose package for handling signals and we here report its suitability for MR images analysis. Khoros^® allows to create workspaces where different procedures (also written by the users) can be combined for implementing more complex procedures. We created workspaces for obtaining 2D and 3D images from time domain data which also allow for apodization and zero-filling. The time required for a 3D-FFT (matrix size 128×128×128) is about 12 min with the presently used microprocessor. We have also created workspaces for calculating apparent diffusion coefficient maps and for segmentation of MR images. Our results demonstrate that a personal computer equipped with public-domain software can represent a powerful tool to fulfil the MRI laboratory common needs.