气温对浙江电网用电量影响的研究

针对近年来浙江电网迎峰度夏期间电力供应短缺较严重的严峻情况,以浙江省1999~2002年的用电量和气温数据为基础,从中分离出与气温敏感的气温电量,分析了电量与气温的相关关系,重点研究了气温电量随气温变化的规律,最后提出了完善与改进相关模型的几点建议。由此气温对用电量影响的特点及规律可作为供电调度工作人员的参考信息。     

Ampacity of cables in single open-top cable trays

A mathematical thermal model that can predict the operating temperatures for cables when there is load diversity in single, horizontal, open-top cable trays is presented. The model accommodates two different loading scenarios-one in which the heat load is distributed evenly across the cable tray cross-section and a second one which concentrates the heavily loaded cables along the center-line and surrounds them with more lightly loaded cables. The second model is designed to yield a maximum cable temperature and to account for the load diversity that exists in a realistically operated tray. Temperature predictions provided by the model are compared with previous laboratory cable tray experiments and with data collected during a four year study in which cable temperatures were measured in an operating nuclear plant. Reasons for differences between the field data and the computer results are discussed. The model is used to evaluate the conservatism in the ICEA P54-440 as a result of load diversity     

Temperature and current dependences of reliability degradation of buried heterostructure semiconductor lasers

Failure times of semiconductor lasers are usually lengthy under normal aging conditions. Determination of failure times typically involves extrapolation using a sublinear or linear model. It becomes increasingly difficult to experimentally determine activation energy and current exponent since data based on lower temperatures and lower stress currents are required. In this paper, the temperature and current dependences of 1310-nm buried heterostructure (BH) InP lasers were studied. We show that the activation energy of 1310-nm BH lasers based on life test data at 70/spl deg/C-100/spl deg/C is higher than the value of 0.4 eV suggested by Telcordia. The activation energies estimated by sublinear and linear models were 0.87 and 0.55 eV, respectively. We also show that the current exponents are 1.4 and 1.0, respectively, for sublinear and linear models. We discuss the implications of the reliability results in field reliability predictions.     

Integrative science: place and future of the model-based information processing

This article examines some of the open issues that should be addressed regarding physiological modeling and information processing to make them central in the future. Coupling model and data through multiple scales and organization levels, multimodal signal and image processing represents a major step in this respect. The capability to bridge physiological models and homogeneous data leads to identification of the systems at hand. However, it is not enough to address a given property of any living system because it has multiple biophysical expressions, all consisting of interdependent or coordinated functions. Structure and function types cannot be easily separated, they are both distinct (large variety and heterogeneity, highly variable behaviors) and connected (with constraints, redundancies, and strong dependency). These issues are examined here together with some more practical considerations.     

Complementary characterization methods for Lithium-ion Polymer secondary battery modeling

This paper deals with the electrical modeling of Lithium-ion Polymer battery, from complementary characterization tests. The first aim of this work is to understand the electrical behavior of this battery through experimentations in the same environmental conditions as the final application’s ones. The second goal of this work is to identify battery models with different precision levels and to implement them in specific models of the considered aircraft electrical network. In this paper, two equivalent electrical circuit models are presented: a quasi-static model, which is functional and sufficient for the electrical energy management in the aircraft; a dynamic model, which is behavioral and necessary for the analysis of the embedded network quality. The identification of their parameters is carried out with adapted characterization tests, such as chronopotentiometry at constant current and Electrochemical Impedance Spectroscopy at different temperatures. The complementarity of these tests is particularly underlined in this paper because it is useful for the parameter identification. The results from model simulation and from experimentation are compared through a mission profile and are analyzed. Eventually, this paper presents complete experimental data for a commercial 4.8 Ah Lithium-ion Polymer battery including the temperature influence.     

基于自组织映射支持向量机的日前电价预测

针对电力市场中日前24点电价特性差异较大、采用单一模型很难描述的特点,建立多个模型分别对其进行预测,将数据空间按时点划分成24个子空间,然后根据这些子空间的相似性通过自组织映射对其进行自动聚类,并在不同类别的子空间分别建立支持向量机模型进行训练和预测。应用上述方法对PJM电力市场2005年8月的31天日前24点电价进行预测,结果表明该方法能够有效提高预测精度。     

Integrated access to heterogeneous data from NCBI

The National Center for Biotechnology Information (NCBI) was created by Congress in 1988 to provide a stable government entity with a leadership role in coping with the information issues associated with this field. The NCBI Software Toolkit permits software tools to be developed in a heterogeneous environment. The use of abstract syntax notation (ASN.I) allows one to specify and exchange data across systems, and to reach biologists in whatever system they choose to work. However, the relevant data are still accumulated by different groups with different data models, different quality standards, in different subject domains, and with different time courses. NCBI has designed a data model to define a number of key data elements for molecular biology, including bibliographic data, nucleic acid sequence, protein sequence, genetic and physical maps, and the information about them. The model was constructed in as much detail as possible to accommodate the data contained in the heterogeneous sources, while still maintaining a common model     

短期负荷预测的实用数据挖掘模型

基于数据挖掘决策树算法和通用的决策支持对象(DSO)建模工具,结合区域电网气象负荷数据库设计与实现了决策树形式的数据挖掘模型并运用于日负荷预测。首先描述了决策树分类方法,分析研究了日负荷预测数据挖掘模型的决策树构造过程,给出了基于DSO的程序化实现,并给出用决策树算法的日负荷预测过程以及实际的预测结果情况。统计分析结果表明该数据挖掘模型完全满足实用标准,具有智能自适应、自学习和全过程自动化、通用可靠以及准确率高等特性。     

A contribution to the study of aging of XLPE insulated cables

The electrical, thermal, and multiple-stress (thermal and electrical) aging of cross-linked polyethylene (XLPE) cable models has been investigated in order to get information on aging effects and mechanisms. After endurance tests, XLPE cable models have been subjected to chemical, physical, electrical, and microstructural characterization. Thermal aging results reveal that bulk degradation occurs in the cables at temperatures higher than the melting point. Multiple-stress aging data emphasize a synergistic effect of electric field and temperature. Significant microstructural changes detected in the cables aged under multiple stress are evidence of this effect and can partly explain the time behavior of the electric strength     

Estimating the parameters of neural mass models including time delay and nonlinearity using a particle filter: a preliminary study toward model‐based EEG analysis

Electroencephalogram (EEG ) and local field potential (LFP ) signals are measured for both experimental and clinical purposes which include sleep stage analyses, brain–computer interfaces, and disease diagnosis. EEG and LFP data analyses are typically based on models assuming that the measured data is generated from a biological system and estimate the model parameter values that most accurately reproduce the measured data. Thus, use of a biologically plausible model is important for a model‐based analysis. However, analyses using models that include time delay and nonlinearity have not been reported, even though they are biologically important for EEG generation mechanisms. In this study, we developed a parameter estimation method that uses a particle filter for models with time delay and nonlinearity, which was evaluated with simulations. Simulated EEG data were generated from neural mass models (NMMs ). The NMM parameters were estimated from the generated data. Furthermore, parameters for modeling EEG features of patients with Alzheimer's disease were included in the NMM ; the disease parameters were estimated from the simulated EEG data. We observed that NMM parameters, as well as the disease parameters, were accurately estimated from the simulated data. We conclude that the validity of our method for estimating parameters of NMMs including time delay and nonlinearity is confirmed for simulated EEG data, and these results show the possibility of using our method for model‐based analysis with real EEG data. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Reliable reduced cost modeling and design optimization of microwave filters using co‐kriging

A reliable methodology for accurate modeling of microwave filter is presented. Our approach exploits co‐kriging that utilizes low‐fidelity and high‐fidelity electromagnetic simulation data and combines them into a single surrogate model. Densely sampled low‐fidelity data determine a trend function, which is further corrected by sparsely sampled high‐fidelity simulations. Low‐fidelity electromagnetic data are also enhanced by using a frequency scaling to reduce its misalignment with the high‐fidelity model. With our method, accurate models can be obtained at a fraction of the cost required by conventional approximation models that are exclusively based on high‐fidelity simulations. Three examples of microstrip filters are considered for verification purposes. We also provide comparisons with conventional approximation models and include an application of co‐kriging models for filter design optimization. Copyright © 2013 John Wiley & Sons, Ltd.     

硅和碳化硅二极管在脉冲功率源中的对比研究

碳化硅功率器件近年来发展很快,具有高击穿电压、高热导率等优点。通过仿真和实验研究了碳化硅二极管作为续流二极管应用在脉冲形成网络中的表现,并与硅二极管作对比。实验结果表明,碳化硅二极管在常温下抗浪涌电流能力不如硅二极管。在高温下两者抗浪涌电流能力均有所减弱,但硅超快恢复二极管的抗浪涌电流能力下降更多。可以预见在更高的温度下,碳化硅肖特基二极管的抗浪涌电流能力将超过硅快恢复二极管。     

聚类算法在锅炉运行参数基准值分析中的应用

大型火力发电厂的实时控制过程中，许多数据之间呈现复杂的非线性关系，而数据挖掘技术能从数据中发现知识或规则，及时分析、调整参数。该文利用数据挖掘方法确定监控参数的基准值，为火电机组耗差分析提供重要依据。介绍了数据挖掘方法的相关理论，研究并应用聚类算法确定热力设备监控参数的基准值模型。采用k-means法分析实时运行数据，分别挖掘再热器压损和锅炉排烟温度的基准值，所得锅炉运行主要监控参数的基准值模型经样本图证实效果良好。为基准值模型的确定提供了一个新的思路和有效方法。     

基于PSpice的品闸管电热模型研究

建立了一种新型的晶闸管PSpice电热模型,包含热模型和电模型,能提供发热和电气参数之间的动态关系,预测晶闸管结温的变化.该模型中所需要的热阻抗参数可以通过有限元方法得到,电气参数可通过数据于册和Matlab等工具得到.PSpice仿真结果与数据于册信息和实际情况相吻合,验证了该模型的实用性.     

Business mobile - Subject - Off the hook

Things are about to change for mobile network operators, although they don't yet know whether it will be for better or worse. What the operators do know is that, unless they find a way to adjust their business models, they risk becoming nothing more than providers of low-cost mobile data connections that carry other people's money- making services. Mobile operators have always thrived on introducing disruptive technologies that were then marketed as vital products and services. They are now becoming victims of their own success. People all over the world behave as if not having a mobile phone is like being deprived of running water. While global subscriber numbers are still growing, saturation and fierce competition in the more mature markets are leading to the inevitable commoditisation of mobile telephony.     

基于SOFM和支持向量机回归的短期负荷预测方法

提出了一种基于自组织特征映射(SOFM)的聚类分析和支持向量机(SVM)的电力系统短期负荷预测方法。该方法首先利用自组织特征映射网络,通过无监督学习策略对训练样本集进行聚类分析,将其分为若干相似子类,再针对每一子类构造一个支持向量机回归模型;使用基于SVM的回归估计算法建立了回归估计函数表达式,给出了基于SOFM和SVM的网络结构;采用河北省某市的实际负荷数据选择样本进行预测。算例表明该方法能够缩短训练时间,提高预测精度。     

等效热网络法和有限元法在轮毂电机温度场计算中的应用

轮毂电机温度场的准确计算对于轮毂电机的安全运行和性能提升至关重要。根据一般电动汽车用轮毂电机样机的结构,建立了等效热网络温度场分析模型和3D有限元模型。基于等效热网络法,编写了轮毂电机温度场计算程序,计算了额定工况下的稳态节点温度。通过有限元法,计算了轮毂电机额定工况下的稳态温度场分布和瞬态温升曲线。根据轮毂电机的温升实验,对比分析了两种方法的计算结果,验证了等效热网络分析模型和3D有限元模型的有效性,说明了等效热网络法和有限元法对于轮毂电机温度场计算的适应性和兼容性。     

600MW机组运行可靠性数据的数学建模与分析

目前,国内积累了大量关于火电机组的可靠性数据,但对它们的统计分析还远远不够。作者对600MW机组的某些可靠性数据进行了统计分析并应用最小二乘法建立了数学模型,同时对该模型进行了分析和应用,发现600MW机组的非计划停运小时、强迫停运小时、降低出力等效停运小时和等效强迫停运率EFOR基本上是按逐年递减的规律变化的,而其等效可用系数则是逐年递增的。     

The brick wall: NP completeness

For over 40 years, artificial intelligence (AI) has not fulfilled its promise of truly intelligent machines for general use. As early as the 1950s and 1960s, scientists developed computational models of intelligence. They then excitedly coded these models into the best computers of the day. At first the scientists were puzzled by the machines' inability to produce reasoned output. Bewilderment became frustration when they realized they had banged into an unforeseen brick wall. This wall had stopped them in their tracks and continues to do so today. AI also has stymied scientists and engineers in other fields such as operations research (the field concerned with determining efficient manufacturing and scheduling protocols), VLSI chip design and testing, and database management. The brick wall exists because many combinatorial problems that are fundamentally important are NP complete. (NP stands for nondeterministic polynomial time.) We illustrate the problem NP completeness causes with an example taken from manufacturing. A general purpose welding device is to be used on an assembly line. It will make numerous welds at predetermined positions on a particular kind of part. The positions will be welded in a specific sequence called a schedule. This schedule is programmed into the welder before a “run”     

Effects of ambient temperature on the performance of bent tubefluorescent lamps

The effects of ambient temperature on the system performance characteristics of bent-tube fluorescent lamps for diameters ranging from T5 to T12 are discussed. Measurements were made from +40°F to +120°F ambient temperature with lamp currents ranging from 0.25 to 0.45 A. Results show that the light output and lamp efficacy peak at higher ambient temperatures for the smaller-diameter T5 biaxial lamp types as compared to the larger T8 and T12 diameter lamps. These data are important from a luminaire design standpoint because they indicate how the thermal characteristics of the fixture affect the system performance. It is concluded that be designing the luminaire geometry to give optimal bulb-wall temperatures improved system performance characteristics can be achieved