A Refined Method for Estimating the Annual Extreme Wave Heights at A Project Site

This paper presents a refined method for estimating the annual extreme wave heights at a coastal or offshore project site on the basis of the data acquired at some nearby routine hydrographic stations. This method is based on the orthogonality principle in linear mean square estimation of stochastic processes. The error of the method is analyzed and compared with that of the conventional method. It is found that the method is able to effectively reduce the error so long as some feasible measures are adopted. A simulated test of the method has been conducted in a large scale wind wave flume. The test results are in good agreement with those given by theoretical error analysis. A scheme to implement the method is proposed on the basis of error analysis. The scheme is so designed as to reduce the estimation error as far as possible. This method is also suitable to utilizing satellite wave data for the estimation.

Methods for Estimating Mean Annual Rate of Earthquakes in Moderate and Low Seismicity Regions

Two kinds of methods for determining seismic parameters are presented, that is, the potential seismic source zoning method and grid-spatially smoothing method. The Gaussian smoothing method and the modified Gaussian smoothing method are described in detail, and a comprehensive analysis of the advantages and disadvantages of these methods is made. Then, we take centrai China as the study region, and use the Gaussian smoothing method and potential seismic source zoning method to build seismic models to calculate the mean annual seismic rate. Seismic hazard is calculated using the probabilistic seismic hazard analysis method to construct the ground motion acceleration zoning maps. The differences between the maps and these models are discussed and the causes are investigated. The results show that the spatial smoothing method is suitable for estimating the seismic hazard over the moderate and low seismicity regions or the hazard caused by background seismicity; while the potential seismic source zoning method is suitable for estimating the seismic hazard in well-defined seismotectonics. Combining the spatial smoothing method and the potential seismic source zoning method with an integrated account of the seismicity and known seismotectonics is a feasible approach to estimate the seismic hazard in moderate and low seismicity regions.

Electromagnetic response function for the semi-annual variations estimated by the single-station method using the night-time values of the geomagnetic fields

The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estimate the Q1 value using the single-station Z/H method. This technique enables us to carry out regional deep gcomagnetic sounding by the method. The data used for analyses are geomagnetic night-time values for about, typically, 26 years from 5 good-quality stations and for several years from 34 stations distributed over the globe. The results indicate that the night-time values yield more reliable response estimates for half-year period compared to the usual estimates obtained from daily means. It implies that the approximation for the night-time fields holds good for the half-year period, but the daily means are not suitable for estimating the response function of the semi-annual variations by using the single-station method. Source field analyses for daily means data and night-time means data have also been carried out in this paper.

郑州市暴雨强度公式计算与对比分析

为真实客观地反映郑州市近年来暴雨特征变化,进一步优化郑州市暴雨强度公式,选取2000~2022年11个降雨历时的年最大暴雨量,采用最小二乘法、遗传算法、拟牛顿法优化了郑州市暴雨强度公式参数,并与郑州市2002年暴雨强度公式以及2023年暴雨强度公式进行对比分析。结果表明,郑州市暴雨强度公式在指数分布中采用拟牛顿法拟合误差最小,最终确定的优化参数A1为11.312、C为2.968、b为19.8、n为0.900;在不同重现期暴雨条件下,优化公式相对于2002年公式呈现出完全不同的极值分布情况,即“大的更大、小的更小”,而与2023年公式的雨强相差较小;在不同降雨情景管网水力运行特征中,优化公式与2023年公式的模拟结果高度一致,两者在预测郑州市内涝情况整体上具有相似的准确性和可靠性,对城市排水防涝具有一定的指导作用。

基于正交试验法的太阳能复合热水系统优化

为降低生活热水能耗,实现空气源热泵辅助太阳能供热水系统的高效节能运行,选取济南市某高校学生宿舍空气源热泵辅助太阳能供热水系统作为研究对象,利用瞬时系统模拟软件搭建了系统仿真模型,并采用无交互作用的正交试验法,分别以全年系统性能系数和太阳能保证率为优化目标,优化了太阳能集热器面积、集热器倾角、热泵制热功率及水箱容积,并分析其结果的经济性和节能性。结果表明:当以系统性能系数为优化目标时,最优组合中集热器面积为390 m^(2)、集热器倾角为42°、热泵制热功率为50 kW、水箱容积为23.94 m3,而动态费用年值为7.38万元,较天然气系统年节省标煤为17.12 tce;当以太阳能保证率为优化目标时,最优组合中集热器面积为342 m^(2)、集热器倾角为44°、热泵制热功率为35.5 kW、水箱容积为20.58 m3,而动态费用年值为6.56万元,较天然气系统年节省标煤为16.63 tce。

利用短序列高密度台站资料推算暴雨重现期方法研究及应用

暴雨重现期是城市排水防涝设计的重要基础,通常基于长年代观测数据进行推算。但在无降水观测或观测时间较短的情况下,如何进行重现期推算和暴雨强度评估是目前亟需解决的科学问题。基于重庆市近14年高密度台站降水观测资料,建立各站逐年日降水极值抽样数据集,以“空间换时间”的思想,对日降水极值样本进行空间抽样,通过与国家级气象站长序列观测数据(>60 a)进行交叉检验,构建试验区目标点最佳百分位合成序列,该方法简称为空间抽样合成法(SBS)。通过重庆地区34个测站长年代观测资料计算重现期降水量“真值”与SBS、邻近点替换、克雷斯曼(Cressman)空间插值、年多个样法等推算结果进行对比检验,就平均而言,SBS的相对误差最小,其中含目标点样本的SBS相对误差最小为7.2%,邻近点替代法相对误差最大(13.2%),表明SBS可以较好地用于中国复杂地形的重庆地区,利用短序列高密度台站降水资料构建无有效降水观测资料目标点处的长序列极值降水样本,从而开展概率拟合优选及暴雨重现期推算。在对上述方法验证基础上,实现重庆地区2062个高密度气象观测站多年(50 a)一遇重现期降水量推算,提高了日尺度极端降水的空间精细化水平,结果能更好反映山区地形对降水的影响。SBS可以充分利用短序列高密度台站降水观测资料,实现区域内任意目标点重现期降水量推算。

考虑时段校核和季节性储能的多区互联电力系统年度发电计划

随着新能源发电量占比的提高,新能源发电量季节性波动引起的年度电力电量平衡问题更加明显。建立年度发电计划模型,提出一种典型时段校核方法;在年度发电计划制定的过程中引入季节性储能设备,建立季节性储氢模型和考虑水头位置的季节性抽水蓄能线性化模型;为了应对新能源出力的不确定性,提出考虑时段校核和季节性储能的年度发电计划三阶段建模方法。算例结果验证了所提模型的有效性。

赣江流域水文干旱事件重现期计算方法

针对以径流相对亏缺状态表征的水文干旱事件,采用3种常用的概率分布函数Log-normal、Gamma和Normal,拟合了赣江外洲站实测年径流资料;利用外洲站年径流的统计特征,推导了干旱历时和干旱强度2种典型干旱特征变量的理论概率分布函数的参数;计算了期望间隔时间定义下干旱历时内累积干旱强度达到某一阈值的干旱事件的重现期,并采用Monte Carlo随机模拟技术进行了验证。结果表明:根据年径流统计信息解析推求水文干旱事件的重现期,具有较强的统计基础和可信的精度,能够一定程度克服依靠有限观测水文序列进行干旱事件重现期推断的样本偏差,可为定量评估流域干旱风险,支撑流域水安全保障提供新的思路。

基于物元可拓法的高潜水位煤矿区土地损毁程度评价

高潜水位煤矿区井工开采造成了地面塌陷积水、农田减产等情况,但积水农田的损毁程度、损毁范围较难获取;加之高潜水位煤矿区采煤沉陷土地具有典型的不确定性和模糊性,因此,科学进行土地损毁程度评定成为矿区土地复垦方案编制和受损农民补偿标准制定的理论基础。采用熵权法确定积水时长、下沉深度、倾斜变形(东西方向,南北方向)、曲率(东西方向,南北方向)、水平变形(东西方向,南北方向)和水平移动(东西方向,南北方向)10种指标的权重,将极限条件法和可拓评价方法相结合,对芡实地、水稻玉米田和莲藕池共计34个评价单元的土地损毁程度进行评价。研究结果表明:芡实地总面积为444.7hm^(2),中度损毁面积为135.7hm^(2),占比30.51%;水稻玉米田总面积为747.2hm^(2),整体属于轻度损毁状态;莲藕池总损毁面积为562.6 hm^(2),中度损毁面积为151.8 hm^(2),占比26.98%;研究区整体土地损毁程度较好。研究结论为科学确定土地损毁程度及范围提供理论支撑,对地区土地复垦方案编制及损毁补偿标准制定具有重要意义。

吴川市暴雨强度公式的推导及评估

为进一步做好城市排水系统的科学性和实用性,采用吴川市国家气象观测站1980—2021年逐分钟雨量数据资料,利用年最大值法、数值逼近和最小二乘法等,推导吴川市暴雨强度公式,结果表明:湛江市暴雨强度公式理论值与吴川市实际值误差太大,不能达到室外排水规范的要求,而推导的暴雨强度区间参数公式和暴雨强度综合公式精度均符合精度要求,可作为相关部门设计吴川市排水基础设施的相关参考依据,且暴雨强度区间参数公式精度明显优于暴雨强度综合公式。

基于动态规划法的水库优化调度研究

水库的调度优化受到许多因素的影响,需从全局的角度出发,对水库系统进行优化。为了提高水库的发电效率,建立水库的动态规划模型,并对调度方案进行优化。结果显示,优化调度方案在丰水年对发电量的提升效果较为明显,常规调度方案与优化调度方案之间的年均发电量差值为288×10^(4)kW·h;优化调度方案对平水年的发电量提升效果次之,两种方案之间的年均发电量差值为209×10^(4)kW·h;优化调度方案对枯水年的发电量提升较不显著,二者间的年均发电量差值仅为23×10^(4)kW·h。研究表明,在丰水年,采用动态规划模型得出的优化调度方案的实施效果较好,而在枯水年,采用优化调度方案对发电量的提升效果较不明显。当流量较大时,水头损失增长量较小,为了提高发电效率,可提高尾水位高度,以达到增大流量及发电量同时控制水头损失的目的。

基于不同选样方法的雨潮遭遇风险分析

感潮地区内涝灾害的发生同时受涝区暴雨与承泄区潮位2个致灾因子影响,在雨潮遭遇风险分析过程中,不同的选样方法将对分析结果造成影响。以中(山)珠(海)联围感潮地区为例,基于年最值选样法与超阈值选样法并结合Copula函数,对研究区雨潮遭遇风险进行分析,结果表明:①超阈值1 d降雨样本序列具有更大的样本容量,其包含更多降雨量较大的暴雨事件,同时这些较大的暴雨事件往往会与高潮位相遭遇;②由于超阈值样本序列包含了更多有效的雨潮事件数据信息,从防洪排涝规划设计的角度考虑,采用超阈值选样法得到的雨潮边缘分布更为安全,且具有更高的准确性;③基于超阈值选样法得到的雨潮联合分布具有更高的拟合优度,同时在年最值样本序列遗漏掉一些较大的暴雨信息的情况下,由超阈值样本序列计算得到的非期望雨潮组合事件发生的概率要较大一些。

贺州市2018—2023年农田灌溉水有效利用系数年间变化分析

农田灌溉水有效利用系数是农作物利用的净灌溉水量与水源渠首处总灌溉引水量的比值,它反映灌区渠系输水和田间用水状况,能综合反映灌区灌溉工程状况、用水管理水平、灌溉技术水平等。贺州市选择了18个样点灌区,采用“首尾测定法”计算各样点灌区灌溉水有效利用系数并推算得全市农田灌溉水有效利用系数,通过对2018—2023年贺州市灌溉水有效利用系数年间变化对比分析,发现贺州市农田灌溉水有效利用系数逐年上升,预计在未来一段时间内仍将保持平缓增长态势。

ANNUAL PRODUCTION OF FIVE SPECIES OF CHIRONOMIDAE (DIPTERA)IN HOUHU LAKE,A TYPICAL ALGAL LAKE(WUHAN,CHINA)

Annual production and life cycle of five dominant species of Chironomidae (Chironomus plumosus, Cryptochironomus sp.,Tokunagayusurika akamusi, Procladius sp.,Clinotanypus sp.) were studied with samples collected monthly from April, 1996 to March, 1997 in Houhu Lake at four stations. Based on instar-frequency data,C. plumosus was univoltine, while the other four were bivoltine. Production rates in grams wet weight m?2a?1 calculated by the size-frequency method wereC. plumosus, 2.170;Cryptochironomus sp., 0.602;T. akamusi, 3.160;Procladius sp., 0.964;Clinotanypus sp., 0.390. Their P/B ratios were 3.9, 4.9, 4.4, 5.3 and 6.6, respectively.

Quantitative research of annual runoff distribution characteristics in the Dagujia River basin,Yantai,China

Mann-Kendall method and minimum variance method are used in this study to analyze the mean value variable-point of the runoff data observed by Fushan Hydrological Station in the Dagujia River basin from 1966 to 2004. Based on the results, the runoff time is divided into four periods with the similar hydrological variation character. The annual runoff distribution characters in the Dagujia River basin are discussed by using the non-uniform coefficients, concentration degree and concentration period, variation range, etc. The results indicate that: (1) River runoff is very unevenly distributed throughout the year in Dagujia River. About 90% of runoff is in the period from June to October, while the runoff from November to April of the next year is lower. (2) The annual runoff distribution characters during 1966-1971 are very similar to that of 1982-1996, and the runoff of 1972-1981 is almost similar to that of 1997-2004. (3) The annual runoff distribution characters have changed obviously during 1997-2004 compared with the other periods, which makes it more difficult to exploit and use the water resource in the future.

An Empirical Analysis of the Annual Report Effect of High Market Capitalization Companies in China

In this paper,we study the abnormal stock price returns of the top 10 stocks in the Chinese stock market in terms of total market capitalization before and after the release of their annual reports in the past 10 years,using the event study method implemented by the Event Study package of the Alpha Library under Python,using a market model to estimate normal returns.The results find that and most of the events have insider phenomenon.

An Advanced Simple Method for Generating Synthetic Average Instant Hourly Solar Energy

The main objective of this study is to generate accurate synthetic hourly solar radiation data by using an easily accessible open source data.In this regard,a new approach is proposed for estimation of synthetic hourly global solar radiation during the day by utilizing only annual solar energy data.First time in literature,a model has been developed for prediction hourly and daily solar radiation based on annual solar energy parameter in this study.Parameters of the model were generated and tested for Turkey and one of them was presented as a case study within this paper.Long term measured hourly horizontal solar irradiance data from a network of Turkish meteorological stations was used to calibrate the model function.The predictions are compared with the solar data available in literature for Turkey.The advanced simple new model is utilized in open source computer program and has the potential to be adapted to other countries.

城市年用水量聚类分析

一年内城市用水量变化既有周期性又有变化性,为总体掌握一年内城市用水量的变化规律,利用K均值聚类算法进行分析。K均值聚类算法具有模式识别和异常值诊断功能,为获得接近全局最优结果,通常需要针对不同的分类质心初始值进行计算。考虑到类别数K值不是预先指定的,需要尝试采用不同的K值进行分析。以华东某城市的某年各日用水量作为原始数据,首先,针对小时用水量变化的上凸或下凹特性,引入加权方法修正异常值;然后,根据计算结果,分析了生成各类别用水的特点。其中,典型特征包括春节前后的用水量较低,“五一”和“十一”两个小长假用水具有相似性。分析结果对于城市用水量管理和供水运行调度具有重要参考价值。

基于蝴蝶优化的配电线路双层迭代降损方法研究

为解决10 kV长配电线路损耗大、电压质量差及降损设备年投资回报率低等问题,提出一种结合蝴蝶优化的配电线路双层迭代降损增效方法。首先,考虑线路负荷三相不平衡,应用电力系统仿真软件Open DSS建立目标配电线路分相潮流仿真模型。其次,增加10 kV线路无功补偿装置容量与位置以及调压器分接头挡位与位置为控制变量,建立以考虑全寿命周期成本(lifecyclecost,LCC)的年投资回报率最大为目标的外层规划模型,以年有功损耗及年平均电压偏移量最小的多目标为内层运行模型。然后,利用蝴蝶算法通过Python调用Open DSS潮流计算模型仿真,得到潮流结果和理论线损并求解降损模型。最后,以某供电公司线路为算例进行验证,结果表明该方法能为线路降损提供实用的实施方案。

麦玉复种连作田土壤性状及周年产量对耕作与施肥的响应

保护性耕作与有机肥施用是黄土高原旱作农业区缓解生态脆弱问题的有效解决手段之一,合理的耕作与施肥措施对山西中部旱区实现麦玉一年两熟具有重要意义。以黄土高原旱作农田为研究对象,采用裂区试验设计,主区为3种耕作方式(深翻(DT)、深松(SS)、免耕(NT)),副区为4种施肥水平(不施肥对照(CK)、全量化肥(CF)、50%化肥+50%有机肥(OF)、全量有机肥(OM)),探究不同耕作与施肥方式下土壤容重、速效养分及麦玉周年产量的变化特征。结果表明,有机肥施用后SS、NT处理0~20 cm土壤容重较DT处理有所下降,其中小麦季SS+OF处理下耕层土壤容重为1.13 g/cm^(3),显著低于DT+OF处理。整个周年复种连作体系中,以NT+OM处理土壤质量含水量最高,较其他施肥处理平均升高7.88百分点;SS+OM处理下土壤的三相比更为理想,三相比偏离值偏低。3种耕作方式下,碱解氮与有效磷含量大小总体呈现OM>OF>CF>CK的趋势,速效钾含量与施肥方式存在极显著关系,其中CF处理下含量最高;玉米季增施有机肥较单施化肥显著提高了糯玉米鲜穗产量,但有机肥施用比例间的差异并不显著,SS+OM处理下麦玉周年产量最高,达19145 kg/hm 2。综上,该试验条件下,SS、NT耕作方式与有机肥施用结合可明显改善土壤的物理性状,碱解氮与有效磷含量也有一定程度的提升,其中,SS+OM处理更有利于黄土高原地区麦玉周年复种连作田产量的提升。