负荷历时曲线法在东辽河流域最大日负荷量中的应用

根据东辽河王奔水文站2000～2009年的水文、水质数据,构建了主要污染物氨氮和化学需氧量负荷历时曲线,计算了东辽河流域氨氮和化学需氧量的最大日负荷量,分析了各污染物最大日负荷的年内变化特征及各类污染源的贡献。结果表明,在25%、50%、75%和90%的保证率下,负荷历时曲线法计算得到的氨氮最大日负荷分别为368.9、153.8、31.8、0.35kg/d,化学需氧量最大日负荷分别为7 378.6、3 058.6、635.9、6.91kg/d;东辽河在6～9月的丰水期具有较高的纳污能力,1、2月纳污能力最弱;污染物的超标点主要集中于保证率10%～70%之间,削减目标主要为非点源。     

Empirical correlations for the climate data in the Kingdom of Bahrain

The Average yearly recorded weather data in the Kingdom of Bahrain over an extended period ranging from 1902 to 2002 for the temperature and from 1962 to 2002 for the atmospheric pressure, the relative humidity, the wind speed and the sunshine duration (i.e. long-term data), is statistically analyzed and empirically modeled. Regression methods, including polynomial and sinusoidal models, are used to fit the data. Polynomial fits are used in modeling the average yearly variations. The obtained coefficients of determination (R²) of these fits are tabulated. In addition, we empirically modeled the monthly variations of the climate parameters using both polynomial as well as sinusoidal regression models. Our results were compared with similar studies for nearby countries, i.e. Oman and Kuwait. The values of R² for both fits are also tabulated.     

基于最大内接的圆曲线拟合算法编程

圆曲线拟合方法有多种,如机械元件配合的需要,必须对圆形件的测量样本点进行“最大内接圆”（或“最小外接圆”）进行拟合。目前解决这一问题多为近似算法。笔者通过论证以说明“最大内接圆”必含于特殊圆的集合之中,该集合由所有过三点的内接圆（含内切圆）构成。通过逐步逼近的方法,遍寻满足条件的内接圆,构成内接圆集合。最后通过半径比较,找出符合“最大内接”的圆拟合曲线。     

辅助弃风消纳的IVMD-LSTM电网典型时段负荷曲线拟合方法

准确地拟合负荷数据是表征负荷特性的关键环节。文章以电力网建设为背景,提出一种改进变分模态分解(Improved Variational Mode Decomposition,IVMD)和长短期记忆网络(Long Short-Term Memory,LSTM)结合的电网中长期典型时段负荷曲线拟合方法。该方法首先将曲率作为量化指标,减小常规VMD方法中K值的不确定性;其次,考虑高渗透率灵活负荷并网条件,精细化拟合特殊时段电网负荷,给出IVMD-LSTM的自适应电网负荷降噪及曲线拟合方法,提高负荷曲线拟合精度和效率;最后,通过实际算例证明了所提方法可有效减小电网典型时段负荷曲线拟合误差,辅助弃风消纳。     

Feed-in tariff structure development for photovoltaic electricity and the associated benefits for the Kingdom of Bahrain

In this study, the feed-in tariff (FIT) scheme was considered to facilitate an effective introduction of renewable energy in the Kingdom of Bahrain. An economic model was developed for the estimation of feasible FIT rates for photovoltaic (PV) electricity on a residential scale. The calculations of FIT rates were based mainly on the local solar radiation, the cost of a grid-connected PV system, the operation and maintenance cost, and the provided financial support. The net present value and internal rate of return methods were selected for model evaluation with the guide of simple payback period to determine the cost of energy and feasible FIT rates under several scenarios involving different capital rebate percentages, loan down payment percentages, and PV system costs. Moreover, to capitalise on the FIT benefits, its impact on the stakeholders beyond the households was investigated in terms of natural gas savings, emissions cutback, job creation, and PV-electricity contribution towards the energy demand growth. The study recommended the introduction of the FIT scheme in the Kingdom of Bahrain due to its considerable benefits through a setup where each household would purchase the PV system through a loan, with the government and the electricity customers sharing the FIT cost.     

中国水库年最高水位统计特性分析（英）

对中国 1 60个水库年最高水位纪录资料的统计特性进行了分析 .研究结果表明 ,水库年最高水位为独立随机变量 ,可用三参数 (均值、Cv 和 Cs)对数正态分布描述 ,其参数与水库特性和水文地区有关 ,宜采用概率权重矩法估计。建立的多元回归方程对工程应用是有益的。在设计标准期内 ,水库年最高水位的分布可近似表示为正态分布 ,这对水库大坝结构安全设计的可靠性估计是十分有用的     

辽宁省年最大24h降水时空特征

为分析辽宁省最大24h降水时空特征,选取辽宁省46个雨量站1964~2013年的年最大24h降水量资料,利用EOF和REOF方法分析了辽宁省年最大24h降水量空间分布和时间变化。结果表明,辽宁省年最大24h降水量多年均值由东南部向西北部递减,总体呈带状分布,最大24h降水量的历史极值也大体由东南向西北递减;最大24h降水量在全省一致偏多或偏少,不同区域反向变化;辽宁省8个分区的最大24h降水量变化过程无相关性,区域特征明显。     

基于阶跃响应曲线拟合的链条锅炉快速建模方法

以20 t/h链条炉排工业锅炉为对象,采用阶跃响应法获取现场试验数据,再通过阶跃响应曲线求出锅炉对象的传递函数.对阶跃响应曲线先采用"两点法"得出模型参数,再采用"曲线拟合法"对模型参数进行修正,从而实现系统动态特性建模.着重讨论了针对阶跃响应曲线,在"两点法"建模的基础上,进一步采用在MATLAB/SIMULINK软件环境下"曲线拟合法"对模型进行修正,发现"两点法"与"曲线拟合法"相结合的方法可以更准确地对系统进行建模.此方法可为锅炉燃烧优化设计、热力系统仿真研究提供热工对象理论模型,也可用于控制系统调试时控制参数的预选择.     

SGT5-4000F(4)燃气轮机夏季最大负荷研究及应用

为了更好地编制发电计划,须准确掌握燃气轮机在各种工况下的最大负荷。燃气轮机的最大负荷受到环境因素的影响很大,特别是夏季最大负荷非常重要却难以预测。利用Matlab分析了SGT5-4000F(4)燃气轮机夏季运行的大量参数,通过数据模拟得到了联合循环机组夏季最大负荷的性能特点,可以准确预测机组夏季各种工况的最大负荷。将预测结果应用于全厂AGC动态上限控制,可提高机组自动化水平,实现机组经济运行。     

District heating: Estimation of a standard load duration curve

District heating projects are planned with the help of a standard heat load duration curve, being the representation of the most likely load pattern the system will have to meet. A systematic procedure to estimate the standard curve is set up: the daily average outside temperature density function is transformed with a relationship between this temperature and the daily average heat load, resulting in a density over the heat loads. the cumulative distribution of the latter is the day load duration curve. Because the result has to be used for capacity planning, the unitary time interval has to be small, e.g. 1 hour. Therefore, the day curve is refined by incorporating the fluctuations over the day. The hour load duration pattern is approximated analytically using the collocation polynomial technique of Lagrange. Results are in agreement with the postulated standard patterns of the literature. the paper adds to the state of the art primarily by presenting a systematic procedure to derive the curve and by expressing the curve analytically. the systematic approach allows a clear interpretation and an extension of the varous steps of the load analysis.     

Direction Dependence of Savings on Cooling and Heating Loads by Energy Efficient Windows

The energy saving performance of energy efficient windows has strong dependence on window direction. Transmitted insolation level definitely affected the cooling and heating load. Simple simulation on the decrement of cooling load and the increment of heating load of a shading window compared with those of a transparent window show the prospect of energy saving effect clearly.From southeastward to southwestward, shading window even enlarges total heating and cooling loads when the thermal transmission is the same. However, if the shading coefficient of window is switched between summer and winter, total cooling and heating load can be reduced. This result clarifies the importance of ＂smart window＂.     

设计洪水计算中年最大选样法与超定量选样法的比较

利用宜昌站实测径流资料,对年最大选样法和超定量选样法进行比较,两种选样方法简便易算,超定量选样法可从有限的洪水资料中利用更多的洪水信息。在进行洪水频率分析前,检验样本系列的独立性,并利用常用的线型优选方法选择合适的频率线型。结果表明,超定量选样法在设计洪水计算中的结果是可靠的。     

变化环境下黄浦江年最高潮位频率分析

受气候变化及人类活动的影响,近三十多年来黄浦江频繁出现高潮位,以往潮位设计值的可靠性值得商榷。基于吴淞站、黄浦公园站的实测年最高潮位资料,分别选取1912~2010年、1913~2010年的潮位序列,在对潮位资料进行一致性检验、一致性修正的基础上,采用P-Ⅲ和EV-Ⅰ分布进行频率分析。结果表明,仅吴淞站的年最高潮位序列通过一致性检验,而黄浦公园站的潮位序列则需进行一致性修正;两种频率分布曲线对黄浦江年最高潮位设计值的估计相差不大,且千年一遇的设计值均比上海市区目前采用的1985年经水利部批准的千年一遇的设防标准要高,更符合变化环境下实际潮位的上升趋势。研究结果可为上海市防洪规划提供重要依据。     

基于人工神经网络的长江三峡年最大洪峰流量长期预报

将统计相关性分析与模糊方法相结合,识别出影响宜昌站年最大洪峰流量的前期流域降水、大气环流形势等预报因子。比较了LMBP算法、自适应BP算法、变步长BP算法、加动量BP算法等几种常见改进BP算法的优缺点,探讨了BP网络建模过程中存在的问题,建立了LMBP算法和自适应BP算法相耦合的中长期水文预报模型。预报实践表明,所建模型合理、预报效果好、精度高、具有较高的推广和应用价值。     

Discovery of the Maximum Principle

A short history of the discovery of the maximum principle in optimal control theory by L. S. Pontryagin and his associates is presented.     

广东省主要江河年最大洪峰流量与大洋海温的关系分析

针对海温对年最大洪峰的影响,采用相关分析法分析了太平洋区域多年逐月的286个海温格点与广东省四大江河控制站年最大流量系列资料,获得了相关性最为明显的特定时间和特定区域的海温,为年最大洪峰预报提供了理论依据。     

我国各省能源消费与其省会城市年平均温度的相关性研究

本文以国家统计数据为依据,用能源消费走势图、年平均气温走势图以及能源消费—气温散点图的方法对典型能耗大省进行了研究。计算出我国具有相关统计数据的30个省的能源消费及其省会城市的温度变化的Pearson相关系数并将其列表,对表中的数据进行分析并对别的省份进行能源走势图和温度走势图的对照分析。研究结果表明1978年～2008年间各个省份的能源消费与省会城市的温度变化呈现出普遍的较强相关性(以下简称"能温相关性"),而且这种相关性的强弱受着样本省市能源消费量的影响。     

汽轮机循环水系统的稳态仿真数学建模

汽轮机循环水系统是一个冷水与高温水蒸气的热交换系统,其水温与水压的机理数学模型十分复杂,不适用于计算机实时仿真系统。作者利用电厂实测数据,通过一种超曲面拟合的方法,建立了该系统水温与水压的仿真数学模型,该模型计算量较小。仿真结果验证了这种拟合建模方法具有较高的精确度。     

工业热负荷最佳热化系数的计算

最佳热化系数是反映热电联产系统热源最佳结构的一个再要参数。本文通过对实际工业热负荷特性的分析整理得到有代表性的几种热负荷特性,以此为基础,以热电联产系统单位供热能力节能量为优化目标,建立了适用于业热负荷的最佳热化系数计算公式。