Development of River Rating Curves for Simple to Complex Hydraulic Structure Based on Calibrated HEC-RAS Hydraulic Model, in Kwale, Coastal Kenya

Accurate and reliable river flow information is critical to planning and management for sustainable water resources utilization. Most of engineering activities related to hydrologic designs, flood, drought, reservoirs and their operations are heavily dependent on the river flow information derived from river rating curve. The rating curve for a given river section is normally developed from a set of direct stage-discharge measurements for different periods. This involves considerable labour, risk and resources, and presupposes a complex and extensive measuring survey. Extrapolating the rating curve beyond the measured range, as common in many cases, is fraught with errors and uncertainties, due to the complex hydraulic behaviour of the surface water profile in transition from section, channel, downstream and flood plain controls which are often poorly understood with direct measurements. Hydraulic modeling has recently emerged as one of the more promising methods to efficiently develop accurate rating curves for a river section with simple or complex hydraulic structures and conditions. This paper explores the use of a Hydraulic Engineering Center-River Analysis System (HEC-RAS) model to review and develop river rating curves for three hydrometric stations on two rivers in Kwale, coastal Kenya. The HEC-RAS models were set up based on topographical (cross section and longitudinal) survey data for the reaches and engineering drawings for the hydraulic structures commonly used as section controls for flow measurement. The model was calibrated under unsteady state conditions against measured stage-discharge data which were captured using a Velocity Current Meter (Valeport) and an Acoustic Doppler Current Profiler (ADCP) for both low and high flow. The rating curves were extracted from model results and the uncertainty associated with each rating curve analyzed. The results obtained by the HEC-RAS model were satisfactory and deemed acceptable for predicting discharge across the stage range at each river section.

Fragility Curves of Existing RC Buildings Based on Specific Structural Performance Levels

In seismic risk mitigation policies, fragility functions of existing buildings play a fundamental role. In this paper, a procedure to develop analytical fragility curves for Moment Resisting Frame Reinforced Concrete buildings is presented. The design of the selected building typologies was performed according to the codes at the time of construction using force-based methods and the state of the practice at the time of construction. A total of 216 building classes were defined, considering different ages, number of storeys, infill panels, plan dimensions, beam stiffness, and concrete strength. The investigated buildings can be considered low-engineered buildings, using no seismic codes or old seismic codes. The seismic capacity of the selected models representing the existing RC buildings has been evaluated through non-linear dynamic simulations. Seismic response has been analyzed, considering various peak and integral intensity measures and various response parameters, such as ductility demands and Interstorey Drift Ratio (IDR). A new relationship among structural performance, damage levels and interstorey drift ratios for each studied type is introduced, which is calibrated using the damage levels described in EMS98. It is important to highlight that in this study, different thresholds of IDR have been associated with different typologies, considering their different ductility member levels after their different structural responses. Fragility Curves (FCs) for the studied structural types are set up, developed and discussed.

A Review of Geothermal Type-Curves with Damage Effect: A Case of Practical Apply to a Mexican Geothermal Field

A review of the art state was developed about the inflow relationships and their application for reservoir characterization. The theoretical development of the methodology for determining the damage effect using type-curves of the inflow relationships was shown. We show the process followed for achieve the geothermal type-curve affected with damage for reservoirs with mean salinities of 30000 ppm and temperatures up to 350℃. This type-curve was applied using measurement production data in a Mexican geothermal field. According with the obtained results is shown that the methodology for determining the damage effect using production measurements is a sure alternative for the damage effect calculation. It was used an alternative methodology in order to validate the damage presence and the obtained results were consistent. Last thing shows that both methodologies can be combined as a confident manner.

Study on the Internal Relationship between Porter Hypothesis and Environmental Kuznets Curve

Based on theoretical derivation,this paper aims to analyse the internal relationship between Porter Hypothesis and Environmental Kuznets Curve.Conclusions were made:(1)In terms of theoretical analysis and empirical researches,the existence of inverted U-shaped EKC and U-shaped Porter Curve has its rationality,most of the controversy come from the misuse and diversity of empirical methods;(2)The progress of Porter Hypothesis also relys on economic growth,which is compatible with EKC;(3)Similar to EKC,a threshold effect exist in the process of technological progress.Environmental regulation is a driving force to promote the widespread use of green technology and reach the threshold.(4)In the process of speeding up economic development,government should gradually increase the intensity of environmental regulation.

基于多特征符号聚合近似和层次聚类的户变关系识别方法

针对低压配电台区拓扑档案中可能存在的户变关系异常问题,文中提出了一种基于多特征符号聚合近似(MF-SAX)和层次聚类的户变关系识别方法。首先,运用符号聚合近似表达方法将用户电压时间序列转化为字符串序列,并引入电压波动系数和电压变化趋势两个附加参数对其特征表达进行强化。然后,基于编辑距离生成用户电压曲线相似性矩阵,并结合层次聚类算法实现户变关系的识别。最后,实际算例结果表明,提出的方法相比于现有方法准确率更高,误报更少,能直接应对数据缺失的情况,且具有更高的效率。

基于典型计量统计的农业灌溉地下水用水量评估

【目的】利用现有计量统计机井数据准确评估典型地区灌溉农业地下水实际用水量。【方法】基于唐山市不同种植结构典型井灌区地下水计量统计数据,通过典型区域实地调查,结合降水量、农业种植结构、统计年鉴等数据,绘制不同种植结构下降水量与灌溉定额的关系曲线,评估2010年唐山地下水实际用水量。【结果】①水浇地、水田的灌溉定额与降水量的关系曲线分别为y=1.167×10^(7)x^(-1.2773)、y=378796x^(-0.6366),拟合R^(2)分别为0.8990、0.8833。②唐山市2010年降水量条件下不同种植结构作物灌溉定额表现为水田灌溉定额(5763~7649 m^(3)/hm^(2))>大棚灌溉定额(4950 m^(3)/hm^(2))>水浇地灌溉定额(2633~4647 m^(3)/hm^(2))。③唐山市2010年灌溉农业地下水实际开采量评估结果为13.08亿m^(3),与《唐山市水资源公报》数据相差9.42%。【结论】水田灌溉定额要大于大棚和水浇地,利用计量统计数据评估得到的农业地下水开采量可在一定程度上评估北方地区农业地下水实际开采量。

CEO谦卑对企业绩效的非线性影响机制研究

基于高阶理论和社会信息加工理论,通过138家企业的多源多时点数据,探讨了CEO谦卑与企业绩效的非线性关系、作用机制及边界条件。研究结果表明,CEO谦卑与企业绩效之间存在倒U形曲线关系;容错氛围与企业绩效之间存在倒U形曲线关系,容错氛围中介了CEO谦卑和企业绩效之间的倒U形关系;高绩效要求负向调节CEO谦卑和容错氛围与企业绩效的倒U形关系,当企业高绩效要求越低时,倒U形关系越强。

白芥子穴位给药配伍对延胡索乙素药效动力学影响的研究

目的:探讨“冬病夏治”全方配伍和无白芥子配伍延胡索乙素在模型家兔“肺俞”穴皮下药代动力学特征及药代动力学-药效动力学(PK-PD)模型的相关性。方法:支气管哮喘模型家兔随机分成延胡索单方组、缺白芥子组、全方组,微透析技术收集14 h穴位皮下透析液,液相色谱-质谱法(Liquid Chromatography Mass Spectrometry,LCMS)法检测方中君药延胡索主要成分延胡索乙素浓度,获得药代动力学参数;酶联免疫吸附试验(ELISA)法检测对应时间点模型动物血清中IgE水平,获得药效学参数;对药动学、药效学参数进行PK-PD模型拟合。结果:白芥子配伍后的药峰浓度(C_(max))、药时曲线下面积(AUC_(0-t))、平均滞留时间(MRT_(0-t))均显著增加(P<0.01,P<0.01,P<0.05),达峰时间(T_(max))提前(P<0.01);“浓度-时间-效应”三维曲线表明,方中有白芥子配伍时,药效出现更快、消退更慢,起效时间晚于峰浓度,具有一定滞后性。结论:动力学参数、PK-PD模型结果表明,白芥子配伍能够改变“方中君药”——延胡索的主要成分延胡索乙素穴位局部的皮下分布,促进方中君药有效成分快速吸收,延长滞留时间,在方剂中起到主药、改善其他药物分布的“双重”作用。

基于决策曲线分析血清铁蛋白检测在肺炎支原体肺炎中的诊断价值

目的 基于决策曲线(DCA)和剂量反应关系分析血清铁蛋白(SF)在肺炎支原体肺炎(MPP)早期诊断中的价值。方法 选取2016年10月至2021年10月于泰州市人民医院就诊的MPP患者104例为MPP组,另选取同期于泰州市人民医院体检的健康成人90例为健康组。比较两组临床资料,筛选发生MPP的影响因素。分析SF对发生MPP的诊断价值,寻求最佳临界值,并评估SF对MPP的临床预测价值。结果 白细胞计数、C反应蛋白、肿瘤坏死因子-α、乳酸脱氢酶、SF是患者发生MPP的独立危险因素,25-羟维生素D是其保护因素(P<0.05)。剂量反应关系分析结果显示,SF的连续变化与MPP的关联强度呈非线性剂量反应关系(P<0.05),当SF>127.68 ng/mL时,随着SF水平的升高,MPP发生风险越大;DCA分析结果显示,SF对MPP早期预测有重要临床价值。结论 SF具有较高的MPP早期诊断价值,与MPP发生大致呈非线性剂量反应关系,当SF>127.68 ng/mL时,随着SF水平的升高,MPP发生风险越大。

基于混凝土20 h内强度龄期关系曲线确定调压井滑模滑升时间研究

水利水电工程调压井滑模施工中的混凝土强度是一个非常重要的技术参数,且是控制滑模滑升速度的依据,也是滑模能否提升的前提条件。阐述了通过对现场混凝土试件进行抗压强度检测,采用线性回归分析方法得出了该配合比混凝土在20 h内的时间与抗压强度关系曲线,依据该关系式推出了调压井20 h内混凝土随时间增长的连续强度,从而判断出滑模是否满足提升要求,进而确定出滑模的滑升时间。该方法的采用减少了取样频次、检测时间与检测成本,能够更加便捷、快速地在施工现场计算出混凝土强度是否满足滑模滑升要求。

汉江兴隆—蔡甸段2000吨级航道整治工程设计最低通航水位分析

随着兴隆枢纽蓄水运用后,枢纽下游河段的河床发生沿程冲刷,同流量下水位产生不同程度的下降。为确定汉江兴隆—蔡甸段2000吨级航道整治工程设计最低通航水位,采用综合历时曲线法计算航道设计通航流量,通过近期水位-流量关系、枯水期水面比降等确定航道设计最低通航水位。结合通航水位的变化趋势,提出后期根据冲淤变化调整后的地形、设计流量、水位-流量关系等对设计最低通航水位进行实时复核调整,以确保水位下降后设计水位的合理性。

莱芜水文站测验断面水位流量关系定线分析

临时曲线法是水文测站在确定水位流量关系时的常用方法,在采用临时曲线法定线时,经常会出现反曲现象,以及确定多条临时曲线时,相邻曲线流量不接头的问题。本文以莱芜水文站为例,根据2022年实测水位、流量资料,提出了消除反曲以及使相邻曲线流量接头的一些思路和方法。

榆林黄河东线马镇引水工程取水口水位流量关系曲线复核分析

榆林黄河东线马镇引水工程取水口水位流量关系曲线直接影响取水口建筑物的设计,对供水保证率和防洪安全具有重要影响。根据取水口及上下游新测的6处河道大断面,采用恒定非均匀流能量方程推求水面线的方法 ,通过推求不同流量对应的水面线,得到取水口断面水位流量关系曲线。根据复核的水位流量关系曲线和实测的水位流量资料与可行性研究阶段成果综合对比分析,可为取水口工程设计提供更准确合理的依据。

基于ADAMS的小型森林越野车前悬架仿真研究与优化

随着小型森林越野车在复杂地形中应用的广泛性,其前悬架系统的性能对车辆的通过性和稳定性起着决定性作用。文章以动力学仿真软件ADAMS为工具,对小型森林越野车的前悬架系统进行了深入的研究与优化。首先,通过UG软件实体建模,确定小型森林越野车前悬架各个硬点参数,然后Adamas-car构建了前悬架系统的虚拟样机模型,仿真分析车轮上下跳动参数与外倾角、主销后倾角、主销内倾角、前束角变化曲线关系,在此基础上,采用ADAMS-Insight进行优化设计,外倾角的变化量减小了1.22°,主销内倾角的变化量减小了0.7°,主销后倾角的变化量减小了8.04°,其性能均得到了一定的优化改善;前束角的变化量略有增加,增加了0.03°,通过优化前后数据对比,优化后的每项参数值都得到了一定的改善,提升了小型森林越野车的稳定性和操控性。文章的研究成果不仅提升了小型森林越野车的性能,也为类似车辆的悬架系统设计提供了理论参考和工程指导意义。

钢轨铣磨技术在高速铁路小半径曲线的应用

为解决高速铁路进出站或临近管界的小半径曲线钢轨表面疲劳伤损问题,修复钢轨廓形,结合现场调查数据,分析了小半径曲线地段钢轨廓形质量、轨面状态、钢轨廓形偏差和轮轨接触关系。从轮轨关系角度分析了轨面疲劳伤损产生原因,提出了利用钢轨铣磨车和道岔打磨车的综合整治方案。结果表明:铣磨打磨作业后钢轨廓形质量和轨面状态得到明显改善;轮轨接触点分布位置更加合理,分布范围更加均匀,有效避免了轨面应力集中问题;动检车横向加速度明显减小,轮轨接触关系得到改善。

凉山烟区土壤钾素形态变化和供应特征分析

关注土壤钾素有效性及其供给能力,可以为合理施用钾肥,提高作物产量与品质提供科学依据。分别于凉山会东(湿润季风气候区)和德昌(高原季风气候区)2个生态区,选取主要植烟土壤类型(紫色土和红壤),采集0~20 cm、>20~40 cm和>40~60 cm深度土壤,分析了土壤钾素形态以及容量/强度(Q/I)关系曲线参数变化。结果表明:紫色土速效钾含量变化较大,以德昌地区相对较高,会东地区则相对较低;红壤速效钾含量在会东和德昌2个地区差异不大。相对而言,德昌地区植烟紫色土和红壤0~20 cm土层速效钾/全钾较高,分别为1.99%和1.42%。德昌地区紫色土0~20 cm土层钾素Q/I关系曲线的供钾强度指标(AR_(e)^(0K))、非专性吸附钾(-ΔK_(0))、专性吸附钾(K_(x))、活性钾(K_(L))均为最高,分别为57.23×10^(-3)(mol/L)^(1/2)、1.55 cmol/kg、0.56 cmol/kg和2.11 cmol/kg。会东地区紫色土钾素Q/I关系曲线的钾位缓冲容量(PBC^(K))最大,可达104.65 cmol/[kg·(mol/L)^(1/2)](>40~60 cm土层);钾离子交换自由能(-ΔG)则以会东地区红壤>20~40 cm土层的数值最大,为19.86 kJ/mol。综上所述,在烟草生产过程中,德昌地区紫色土区域需要减少钾肥用量,而会东地区紫色土区域则需要持续加大供给钾肥。

A Flexible Model for Moisture-Suction Relationship for Unsaturated Soils and Its Application

The mathematical equation for the moisture-suction relationship also known as soil water characteristic curve (SWCC) is one of the constitutive relations necessary for the computational modeling of deformation and flow problems of unsaturated soil using the finite element method. In this paper, a new empirical equa-tion for the SWCC is developed that incorporates the actual airentry suction and the maximum possible suction of the soil as input parameters. The capability of the new model is investigated by fitting the experimental data for twelve different soils that includes sands, silts, and clays. The model fits the experimental data well including in high suction range which is one of the difficulties observed in other commonly used models such as the Brooks and Corey, van Genuchten, and Fredlund and Xing models. The numerical stability and the performance of the new model at low and high degrees of saturations in finite element simulation are investigated by simulating the dynamic response of a compacted embankment and the results are compared with similar predictions made using widely used SWCC models.

STUDY ON PCT CURVE FOR Zr-Ni HYDROGEN STORAGE AMORPHOUS ALLOY

Based on the comprehensive analysis of hydrogen storageexperimental results for Zr-Ni amor- phous alloy, the quantitativerelationship of PCT curve was established, the calculated results areconsistent with experimental ones.

From Pressure-Volume Relationship to Volume-Energy Relationship: A Thermo-Statistical Model for Alveolar Micromechanics

The connective tissue fiber system and the surfactant system are essential and interdependent components of lung elasticity. Despite considerable efforts over the last decades, we are still far from understanding the quantitative roles of either the connective tissue fiber or the surfactant systems. Through thermo-statistic considerations of alveolar micromechanics, the author introduced a thermo-statistic state function “entropy” to analyze the elastic property of pulmonary parenchyma based on the origami model of alveolar polyhedron. By use of the entropy for alveolar micromechanics, from the logistic equation for the static pressure (P)-volume (V) curves including parameters a, b, c, and k (V - a = b/[1+ exp{-k (P - c)}]), a set of equations was obtained to define the internal energy of lungs (UL) and its corresponding lung volume (VL). Then, by use of parameters a, b, c, and k, an individual volume-internal energy (VL - UL) diagram was constructed from reported data in patients on mechanical ventilation. Each VL - UL diagram constructed was discussed that its minimal value Uo = c (a + b/2) and its shape parameter b/k represent quantitatively the energy of tissue force and the energy of surface force. Furthermore, by use of the VL - UL relationship, the hysteresis of lungs estimated by entropy production was discussed as dependent on the difference in the number of contributing pulmonary lobules. That is, entropy production might be a novel quantitative indicator to estimate the dynamics of the bronchial tree. These values obtained by combinations of parameters of the logistic P-V curve seem useful indicators to optimize setting a mechanical ventilator. Thus, it is necessary to develop easy tools for fitting the individual sigmoid pressure-volume curve measured in the intensive care unit to the logistic equation.

三相不平衡对配电变压器效率影响数学建模与分析

为提高配电变压器效率,找到与低压配电网相匹配的三相负荷不平衡度算法,以及探究三相不平衡对配电变压器效率影响关系,选用常用的配电变压器进行分析。采用数理推导、试验建模、案例与仿真分析的方法进行推究分析,通过建立低压配电系统三相不平衡对铁损、铜损、线损影响的模型进而推导出三相不平衡对配电变压器效率的影响关系。提出了可以有效反映三相不平衡对低压配电网影响关系的三相幅值不平衡度算法、三相功率因数不平衡度算法以及三相负荷不平衡度算法,得到三相负荷不平衡对总损耗、附加损耗以及对配电变压器效率影响的关系曲线,为三相不平衡的治理和节能降损提供了参考依据。