武汉市区近59 a降水变化趋势分析

以武汉市区为例,采用Mann-Kendall趋势分析法与R/S分析法研究了1951～2009年月降水序列、年降水序列特征及趋势检验,并预测了未来降水量.结果表明,月降水序列中1、2、7、11月呈上升趋势,仅1、3月变化趋势显著;年降水序列上升趋势不明显,降水时间序列具有分形特征和长程相关性,可为降水中长期预测和水资源合理利用提供参考.     

基于EEMD-ANN的水库年径流预测

以三峡水库为例,基于集合经验模态分解(EEMD)及人工神经网络方法对水库年径流进行预测。首先利用Mann-Kendall和Pettitt法对水库年径流序列进行突变检测,获得平稳径流序列,然后采取EEMD方法分解径流序列,得到固有模态函数(IMF)和残差,最后对不同IMFs和残差分别建立人工神经网络预测模型,叠加所有模型预测结果得到年径流预测值。结果表明,基于EEMD-ANN的年径流预测模型优于自回归模型和人工神经网络模型,其预测结果与实测值的相关性更强,预测误差分别减少了11.4%、8.7%。同时,构建EEMD-ANN预测模型时需考虑径流序列的突变特征,采取平稳径流序列的预测效果更优。     

基于EMD分解的AR模型在年径流预测中的应用

为提高年径流中长期预测的精度,提出了一种新的时间序列预测方法——基于EMD分解的AR模型,以汾河上游上静游、汾河水库、寨上和兰村四座水文站1956~2000年的年径流序列为例,首先利用经验模态分解(EMD)方法将四座水文站的年径流序列分解为若干个固有模态函数(IMF)分量和一个残余项分量,然后运用自回归(AR)模型分别对各阶IMF进行预测,最后将各阶预测值重构得到年径流量预测值与单独运用AR模型的预测结果进行比较。结果表明,运用基于EMD分解的AR模型对汾河上游年径流进行预测,其预测精度比单独运用AR模型的预测精度有明显提高,表明该方法可行、有效。     

水文时间序列变点分析的贝叶斯方法

建立了用于时间序列变点分析的贝叶斯数学模型，以此来研究随机水文时间序列均值的突变。该模型的核心部分是根据观测到的资料，通过蒙特卡洛马尔科夫链随机抽样的方法来估计变点位置的后验概率分布。对应着最大后验概率的位置被认为是发生变点的最可能位置。该方法在长江宜昌站的年径流资料系列上进行了应用。结果发现，在过去120a，长江宜昌站的年最小流量系列和年均流量系列的均值都极有可能存在着突变，而且其变化趋势都是均值明显减少。     

黑龙江流域气温突变诊断及极值重现期分析

以黑龙江流域44个站点1954~2012年共59年的日气温资料为基础,应用Mann-Kendall法和启发式分割算法,分别对44个站点的年平均气温做气温突变诊断。根据气温突变诊断结果对比分析,选取启发式分割算法结果对年极值序列进行分割,并检验前、后子序列是否服从同一分布。由此应用GEV函数拟合黑龙江流域6个子区域年极值序列,研究其年极值的变化特征。结果表明,随着气温突变,黑龙江流域中部及西北部年最高气温产生明显增长;黑龙江流域中部年最低气温产生明显增长;黑龙江东部年极端气温受气候变化影响较小,无明显变化。     

Fourier analysis of climatological data series in a tropical environment

Monthly-averaged 10-year climatological data series of global solar irradiation, average ambient temperature and mean relative humidity in Ibadan (lat. 7.43° N, long. 3.90° E), Nigeria, have been analysed using the Fourier series method. The pertinent amplitudes, phase angles, and harmonic angles have been obtained for each year of the series and for each variable. The study reveals that only the annual harmonic contributes in any significant way to explain the variance of the average temperature and the mean relative humitidy series, with percentages ranging between 57% and 91% for temperature and between 75% and 93% for the relative humidity. In the case of global solar irradiation, both the first and the second harmonics contribute almost equally to the total variance, with about 40% each. Typical annual time function parameters are provided for each of the three climatological variables.     

江苏省里下河地区降雨变化特性分析

利用江苏省里下河地区14个代表性控制站的降雨资料,通过M-K趋势检验法、有序聚类法、秩和检验法及小波分析法分析了年降雨系列的趋势性、跳跃性及周期性规律。结果表明,该地区年降雨系列存在微弱的减少趋势,1965年发生了不明显跳跃性变异,年降雨量存在21年时间尺度的主周期和5年时间尺度的次周期,2013~2014年年降雨量将处于偏丰阶段,随后将进入约10年的偏枯期。     

基于HHT变换的雅鲁藏布江径流多时间尺度分析

采用HHT变换对雅鲁藏布江流域拉孜等4个典型水文站1956~2000年年径流量进行了多时间尺度分析。结果表明,雅鲁藏布江全流域范围内存在3、6~8、14~16 a的近似周期,与采用小波分析法所得结果吻合,验证了HHT变换有效、可行。该法为水文序列多时间尺度分析提供了一种新途径,值得推广。     

Direct heat utilization of geothermal resources

Direct utilization of geothermal energy consists of various forms for heating and cooling instead of converting the energy for electric power generation. The major areas of direct utilization are (1) swimming, bathing and balneology, (2) space heating and cooling including district heating, (3) agriculture applications, (4) aquaculture applications, (5) industrial processes, and (6) heat pumps. Major direct utilization projects exploiting geothermal energy exist in about 38 countries, and the estimated installed thermal power is almost 9,000 MWt utilizing 37,000 kg/s of fluid. The world-wide thermal energy used is estimated to be at least 108,100 TJ/yr (30,000 GWh/yr) - saving 3.65 million TOE/yr. The majority of this energy use is for space heating (33%), and swimming and bathing (19%). In the USA the installed thermal power is 1874 MWt, and the annual energy use is 13,890 TJ (3,860 GWh). The majority of the use (59 %) is for heat pumps (both ground coupled and water source), with space heating, bathing and swimming, and fish and animal farming each supplying about 10%.     

Is per capita electricity consumption stationary? Time series evidence from OECD countries

This study examines the stationary properties of per capita electricity consumption in which the endogenously determined break points are incorporated in 23 high income OECD countries by using annual data over 1960-2005 period. We utilize Lagrange Multiplier (LM) unit root test that endogenously determines structural breaks in level and/or trend. We find that 21 country series reject the unit root null hypothesis at the 5% significance level, except for 2 country series. Thus, our empirical findings provide significant evidence that per capita electricity consumption is stationary in almost all countries considered in the study. The stationarity of per capita electricity consumption indicates that it should be possible for the series to forecast future movements in the energy consumption based on the past behaviors of the series. Important policy implications emerge from our empirical results of the unit root test with multiple structural breaks.     

百色市区近70年降雨演变规律分析

为研究百色市区降雨演变规律,基于百色气象观测站1951?2019年的降雨资料,采用Mann-Kendall趋势检验法分析了该地区年降雨量的演变趋势,采用R/S分析法分析降雨量演变趋势的持续性,采用小波分析法对百色市区降雨时间序列进行多时间尺度分析,分析出该地区年降雨量的变化周期,采用滑动平均差检测法、累积距平法和Man...     

Techno-economic study of off-grid hybrid photovoltaic/battery and photovoltaic/battery/fuel cell power systems in Kunming,China

The objective of this study is to evaluate the technical and economic feasibility of stand-alone hybrid photovoltaic (PV)/battery and PV/battery/fuel cell (FC) power systems for a community center comprising 100 households in Kunming by using the Hybrid Optimization Model for Electric Renewable (HOMER) software. HOMER is used to define the optimum sizing and techno-economic feasibility of the system equipment based on the geographical and meteorological data of the study region. In this study, different hybrid power systems are analyzed to select the optimum energy system while considering total net present cost (NPC) and levelized cost of energy (COE). The results showed that the optimal hybrid PV/battery system comprised 500 kW PV modules, 1200 7.6-kWh battery units, and 500 kW power converters. The proposed system has an initial cost of $6,670,000, an annual operating cost of $82,763/yr, a total NPC of $7,727,992, and a levelized COE of $1.536/kWh. While the PV/battery/FC power system is possible, the cost increases were due to the investment cost of the FC system. The optimal PV/battery/FC system has an initial cost of $6,763,000, an annual operating cost of $82,312/yr, a total NPC of $7,815,223, and a levelized COE of $1.553/kWh.     

An analysis of wind power potential in Greece

In this paper an analysis of the available wind data for the Aegean Sea region of Greece is carried out to ascertain its potential for wind energy development. The effect of the limited number of daily observations available on the accuracy of the mean wind speed and annual wind energy estimates is ascertained. The applicability of the Weibull distribution is then examined and plots of the Weibull parameters are given. The annual average wind energy flux is calculated and found to be quite high (in excess of 600 W/m² per yr at 10 m) which makes the Aegean Islands likely candidates for wind power utilization.     

浑河干流径流变化及其驱动力分析

根据浑河干流大伙房水库、沈阳和邢家窝棚3个水文控制站1964~2011年的逐月径流资料和逐月降雨资料,运用数理统计、Kendall秩次检验、R/S分析法和M-K突变检验等方法,计算分析了浑河流域径流的年际变化、代际变化、年内分配和径流变化趋势等多种特征,并利用降水—径流双累积曲线法研究了浑河流域降水和人类活动对径流变化的贡献率。结果表明,浑河流域径流的年际变化剧烈,下游的变差系数与极值比大于上游,说明下游更不利于水资源综合利用和管理;浑河干流丰水期历时短,枯水期历时长,大部分年份处于枯水期;浑河干流径流的代际变化不明显,但径流年内分配很不均匀,主要集中在5~10月,约占全年径流量的75%;浑河流域的径流序列呈现出丰枯交替变化,处于不显著递减状态;影响浑河干流径流变化的主要因素是人类活动,其次是降水变化。     

怒江中上游流域降水趋势和周期变化分析

基于怒江贡山水文站以上流域1958～2008年降水资料,运用M-K检验法及Morlet小波函数方法,分别对该流域的年降水和四季降水序列进行了趋势和周期分析,揭示了该流域各降水系列均有增加的趋势,其中年降水系列和春季、冬季降水系列增加趋势明显,并确定了各降水系列的震荡主周期。由此预测未来3～5年内怒江中上游流域年降水和夏季、秋季降水处于偏枯期,春季、冬季降水处于偏丰期。     

基于一致性修正的宁波市甬江口设计高潮位研究

以位于宁波市甬江口的镇海站1951~2013年的年最高潮位序列为例,分别采用Spearman秩次相关检验、M-K检验方法分析其趋势变化,采用滑动秩和检验、Pettitt检验方法检查其变异点,发现该站年最高潮位存在显著上升趋势,且先后在1981、1996年发生跳跃,不同时期的样本并非来自同一总体。因此,选邻近的湖头渡为参证站,划分为1951~1980、1981~1995、1996~2013年三个阶段,建立了镇海站与湖头渡站的高潮位相关关系,以1996~2013年代表现状,对1951~1980、1981~1995年的实测年最高潮位进行修正,使修正后的序列满足频率分析的一致性要求。分别对经修正和未经修正的序列进行频率计算,表明同等频率下前者求出的设计值均大于后者,从而为甬江口涉水工程的规划建设和运行等提供更合理的依据。     

岩溶区流域降雨径流趋势变异分析

为了识别变化环境下岩溶区流域水文序列趋势发生的变异及变异程度并预估未来变化趋势,采用趋势分析法和变异分析法分析了澄碧河水库流域降雨径流序列在3个时间尺度下的趋势性及变异性,并结合相关函数法预估其变化趋势。实例研究表明,流域内降雨序列在不同时间尺度下总体上均呈持续下降趋势(倾向率为-13.6~-32.2mm/10a),相应发生了不同程度的变异(h=0.512~0.956),其中百炼站发生了巨变异,变异强度大致以全年—雨季—枯季尺度递减;年径流与雨季径流呈同步微弱下降趋势,而枯季径流则呈微弱上升趋势,但均处于弱变异(h=0.675)状态;未来一定时期内,水库流域3个时间尺度下降雨序列呈显著下降趋势,而径流则呈微弱减少趋势。     

金沙江上游流域水文循环要素变化特征分析

基于金沙江上游攀枝花和直门达两个水文站及49个气象站1956～2009年的水文气象资料,分析了气温、降水和径流的时空变化特征,并采用Mann-Kendall检验法对各要素的时间变化趋势进行了显著性检验。结果表明,金沙江上游年平均气温和月平均气温均显著升高;年降水量显著增加,但年径流量增加趋势并不显著;月径流量除在春末夏初显著增加外,其他各月均无明显变化。     

Energy efficiency in chinese apartment buildings: Parametric analysis with the DOE-2.1A computer program

Using an uninsulated Beijing apartment house of standard design as a base case, the DOE-2.1A energy analysis program is used to study the cost-effectiveness of more energy-efficient designs. Two measures have attractive simple payback times; reduced infiltration (1–2 yr payback) and insulation of the north wall (6 yr). The cost of conserved coal for the insulation measure is less than half the international price of coal. This insulation adds only 0.6% to the first cost of the building, yet, combined with more attention to infiltration, it reduces annual heat load from 230 to 130 MJ/m². Furthermore, the first cost of these two measures may be offset by savings from downsizing the heating plant. In Shanghai, reduced infiltration and insulation are justified not on the basis of saving fuel, but because they make dwellings more comfortable.     

大伙房水库流域降水变化特征分析

采用五点滑动平均法、趋势系数法、Mann-Kendall趋势检验法和方差分析法对大伙房水库流城1951～2006年的降水资料进行了分析.结果表明,1980年前年降水序列明显下降,1980年后微弱上升;季降水序列中夏季降水与年降水变化基本一致,秋季降水明显下降,春,冬两季降水变化趋势不明显;年降水和季降水序列均具有明显的周期变化规律.这些规律可为大伙房水库流域降水的中长期变化趋势估报提供参考.