The effects of drainage basin geomorphometry on minimum low flow discharge: the study of small watershed in Kelang River Valley in Peninsular Malaysia

This study investigate the relationships between geomorphometric properties and the minimum low flow discharge of undisturbed drainage basins in the Taman Bukit Cahaya Seri Alam Forest Reserve, Peninsular Malaysia. The drainage basins selected were third-order basins so as to facilitate a common base for sampling and performing an unbiased statistical analyses. Three levels of relationships were observed in the study. Significant relationships existed between the geomorphometric properties as shown by the correlation network analysis; secondly, individual geomorphometric properties were observed to influence minimum flow discharge; and finally, the multiple regression model set up showed that minimum flow discharge(Q min) was dependent of basin area(AU), stream length(LS), maximum relief(Hmax), average relief(HAV) and stream frequency(SF). These findings further enforced other studies of this nature that drainage basins were dynamic and functional entities whose operations were governed by complex interrelationships occurring within the basins. Changes to any of the geomorphometric properties would influence their role as basin regulators thus influencing a change in basin response. In the case of the basin’s minimum low flow, a change in any of the properties considered in the regression model influenced the “time to peak" of flow. A shorter time period would mean higher discharge, which is generally considered the prerequisite to flooding. This research also conclude that the role of geomorphometric properties to control the water supply within the stream through out the year even though during the drought and less precipitations months. Drainage basins are sensitive entities and any deteriorations involve will generate reciprocals and response to the water supply as well as the habitat within the areas.

A general multi-objective programming model for minimum ecological flow or water level of inland water bodies

Assessment of ecological flow or water level for water bodies is important for the protection of degraded or degrading ecosystems caused by water shortage in arid regions, and it has become a key issue in water resources planning. In the past several decades, many methods have been proposed to assess ecological flow for rivers and ecological water level for lakes or wetlands. To balance water uses by human and ecosystems, we proposed a general multi-objective programming model to determine minimum ecological flow or water level for inland water bodies, where two objectives are water index for human and habitat index for ecosystems, respectively. Using the weighted sum method for multi-objective optimization, minimum ecological flow or water level can be determined from the breakpoint in the water index–habitat index curve, which is similar to the slope method to determine minimum ecological flow from wetted perimeter–discharge curve. However, the general multi-objective programming model is superior to the slope method in its physical meaning and calculation method. This model provides a general analysis method for ecological water uses of different inland water bodies, and can be used to define minimum ecological flow or water level by choosing appropriate water and habitat indices. Several commonly used flow or water level assessment methods were found to be special cases of the general model, including the wetted perimeter method and the multi-objective physical habitat simulation method for ecological river flow, the inundated forest width method for regeneration flow of floodplain forest and the lake surface area method for ecological lake level. These methods were applied to determine minimum ecological flow or water level for two representative rivers and a lake in northern Xinjiang of China, including minimum ecological flow for the Ertix River, minimum regeneration flow for floodplain forest along the midstream of Kaxgar River, and minimum ecological lake level for the Ebinur Lake. The results illustrated the versatility of the general model, and can provide references for water resources planning and ecosystem protection for these rivers and lake.

Estimating the minimum in-stream flow requirements via wetted perimeter method based on curvature and slope techniques

Under the assumptions of triangular cross section channel and uniform stable flow, an analytical solution of the minimum ecological in-stream flow requirement (MEIFR) is deduced. Based on the analytical solution, the uncertainty of the wetted perimeter method is analyzed by comparing the two techniques for the determination of the critical point on the relationship curve between wetted perimeter, P and discharge, Q. It is clearly shown that the results of MEIFR based on curvature technique (corresponding to the maximum curvature) and slope technique (slope being 1) are significantly different. On the P-Q curve, the slope of the critical point with the maximum curvature is 0.39 and the MEIFR varied prominently with the change of the slope threshold. This indicates that if a certain value of the slope threshold is not available for slope technique, curvature technique may be a better choice. By applying the analytical solution of MEIFR in the losing rivers of the Western Route South-to-North Water Transfer Project in China, the MEIFR value via curvature technique is 2.5%-23.7% of the multi-year average annual discharge, while that for slope technique is 11%-105.7%. General conclusions would rely on the more detailed research for all kinds of cross-sections.

A Parametric Approach to the Bi-criteria Minimum Cost Dynamic Flow Problem

This paper presents an algorithm for solving Bi-criteria Minimum Cost Dynamic Flow (BiCMCDF) problem with continuous flow variables. The approach is to transform a bi-criteria problem into a parametric one by building a single parametric linear cost out of the two initial cost functions. The algorithm consecutively finds efficient extreme points in the decision space by solving a series of minimum parametric cost flow problems with different objective functions. On each of the iterations, the flow is augmented along a cheapest path from the source node to the sink node in the time-space network avoiding the explicit time expansion of the network.

Determination of minimum flood flow for regeneration of floodplain forest from inundated forest width-stage curve

Floods are essential for the regeneration and growth of floodplain forests in arid and semiarid regions.However,river flows,and especially flood flows,have decreased greatly with the increase of water diversion from rivers and/or reservoir regulation,resulting in severe deterioration of floodplain ecosystems.Estimation of the flood stage that will inundate the floodplain forest is necessary for the forest's restoration or protection.To balance water use for economic purposes and floodplain forest protection,the inundated forest width method is proposed for estimating the minimum flood stage for floodplain forests from the inundated forest width-stage curve.The minimum flood stage is defined as the breakpoint of the inundated forest width-stage curve,and is determined directly or analytically from the curve.For the analytical approach,the problem under consideration is described by a multi-objective optimization model,which can be solved by the ideal point method.Then,the flood flow at the minimum flood stage(minimum flood flow),which is useful for flow regulation,can be calculated from the stage-discharge curve.In order to protect the forest in a river floodplain in a semiarid area in Xinjiang subject to reservoir regulation upstream,the proposed method was used to determine the minimum flood stage and flow for the forest.Field survey of hydrology,topography,and forest distribution was carried out at typical cross sections in the floodplain.Based on the survey results,minimum flood flows for six typical cross sections were estimated to be between 306 m3/s and 393 m3/s.Their maximum,393 m3/s,was considered the minimum flood flow for the study river reach.This provides an appropriate flood flow for the protection of floodplain forest and can be used in the regulation of the upstream reservoir.

Calculation and Evaluation of Ecological Flow of Hydropower Station Based on Fuzzy Evaluation Model

The reasonable determination of ecological flow is of great significance for the efforts to promote the transformation of water ecological environmental protection from pollution management to synergistic management of water resources,water ecology and water environment,and to promote them in an integrated manner.This paper analyzed and calculated the ecological flow process of the Bangsha River diversion power station using the minimum ecological flow method,the annual spreading method,the improved annual spreading method,the NGPRP method,and the month-by-month frequency method,and evaluated the reasonableness of the process and results of the ecological flow calculations by using the fuzzy evaluation model established.The study showed that the minimum ecological flow rate determined by improving the coupling of the spreading method and the NGPRP method was the best,and the suitable ecological flow rate determined by the month-by-month frequency method was the best;the minimum ecological flow rate of the Bangsha River diversion power station was at 0.43-4.21 m 3/s,and the suitable ecological flow rate was at 0.56-4.94 m 3/s,and the trend of its change showed the trend of first increasing and then decreasing,and the trend of change from January to July showed the trend of first increasing and then decreasing.Its trend of change showed an increasing and then decreasing trend,from January to July showed a gradually increasing trend,from August to December showed a gradually decreasing trend.It aimed to provide a theoretical basis for the reasonable determination of the ecological flow of the river hydropower station.

Identification of Prorocentrum minimum and Takayama pulchella by fluorescence in situ hybridization through epifluorescence microscopy and flow cytometry

Partial rDNA sequences of Prorocentrum minimum and Takayama pulchella were amplified, cloned and sequenced, and these sequence data were deposited in the GenBank. Eight oligonucleotide probes (DNA probes) were designed based on the sequence analysis. The probes were employed to detect and identify P. minimum and T. pulchella in unialgal and mixed algal samples with a fluorescence in situ hybridization method using flow cytometry. Epifluorescence micrographs showed that these specific probes labeled with fluorescein isothiocyanate entered the algal cells and bound to target sequences, and the fluorescence signal resulting from whole-cell hybridization varied from probe to probe. These DNA probes and the hybridization protocol we developed were specific and effective for P. minimum and T. pulchella, without any specific binding to other algal species. The hybridization efficiency of different probes specific to P. minimum was in the order: PM18S02 > PM28S02 > PM28S01 > PM18S01, and that of the probes specific to T. pulchella was TP18S02 > TP28S01 > TP28S02 > TP18S01. The different hybridization efficiency of the DNA probes could also be shown in the fluorescent signals between the labeled and unlabeled cells demonstrated using flow cytometry. The DNA probes PM18S02, PM28S02, TP18S02 and TP28S01, and the protocol, were also useful for the detection of algae in natural samples.

认知物联网中继传感节点最小功耗布置方法研究

物联网数据传输过程中,中继传感节点能量不足或者能量消耗过多将导致部分节点失效,降低物联网的使用寿命。为解决这一问题,提出认知物联网中继传感节点最小功耗布置方法。根据中继节点结构特征、有向加权图,建立数据传输功耗的数学模型;以最小功耗布置为目的,制定数据流向、通信容量、数据最大传输次数的约束条件,阻止中继节点逆向传输,使节点满足通信容量范围的同时,避免出现逐条传输数据的事件;引入贪婪算法布置中继传感节点,实现中继传感节点最小功耗布置。仿真结果表明,所提方法的中继传感节点布置最大功耗为17.58 J;在传感节点分布密度为370个/m^(3)时,中继节点布置数量为126个;在11.9 s内即可完成150个中继节点的布置。

THE ENTROPY-FLOW METHOD FOR DETERMINING THE MINIMUM WORK IN AN AIR-EXHAUSTING PROCESS

The thermodynamic system consists of the entropy flow and entropy product.This paper is to define the entropy flow and to apply it to determinig the minimal work in air-exhausting processes.It is found that the minimum work depends only on the pressure at the negative-pressure space.

基于组合流量法的城市供水系统小区漏损诊断和预警

近年来,城市供水管网漏损问题频发,小区供水管网作为供水管网的最后一公里,降低小区管网漏损已成为供水企业的重要工作内容。文章针对夜间最小流量移动平均隔差法诊断不及时等问题,提出了一种基于全天流量的判别阈值矩阵分析的漏损诊断预警方法,利用全天流量趋势构建判别阈值矩阵诊断漏损,还将基于全天流量的判别阈值矩阵分析法与夜间最小流量移动平均隔差法结合,提出了一种基于全天流量和夜间最小流量的组合型漏损诊断预警法。将夜间最小流量移动平均隔差法、基于全天流量的判别阈值矩阵分析法和组合流量法分别应用于S市的30个DMA小区,识别准确率分别可以达到73.52%、78.19%和91.28%。结果表明,文章提出的基于全天流量的判别阈值矩阵分析法以及组合型漏损诊断预警法在解决小区供水管网漏损问题方面具有较好的应用前景和实际效果。

基于分子动力学方法的致密砂岩储层CO_(2)驱油研究进展

随着致密砂岩储层CO_(2)-EOR项目的不断增加,亟需对CO_(2)与致密砂岩储层流体在孔隙介质中的相互作用机理进行研究,但室内实验难以观察到CO_(2)与流体在孔隙通道中的动态过程,而分子动力学模拟则可以弥补传统实验和数值方法的不足。为此,围绕该方法在CO_(2)-EOR研究中的2大重点——界面行为与受限空间运移行为,对包括萃取、溶胀、降黏、降低界面张力、最小混相压力、润湿性等6个方面界面行为的相关研究成果进行了系统梳理,结合前人对CO_(2)与致密砂岩储层流体在受限空间中运移行为的研究成果,提出了分子动力学在致密砂岩储层CO_(2)-EOR研究中的关键科学问题。研究结果表明:①分子动力学能够很好地将CO_(2)萃取原油中—轻烃组分的过程进行可视化,建议根据原油实际组分构成分析CO_(2)的萃取能力,从而弄清CO_(2)萃取原油中各组分的优先顺序及效率;②有关CO_(2)分子对原油溶胀降黏作用的研究,大多数成果中的原油组分体系较为单一,建议根据实际储层的原油组分,系统探讨高温高压条件下CO_(2)的溶胀降黏作用;③对于CO_(2)与油水两相之间界面张力的研究更多是在体相中进行展开,而在纳米受限空间界面行为的研究还有待完善;④有关地层水在孔隙壁面的润湿性研究,对不同因素之间的协同效应影响润湿性的机理尚不明确。结论认为,随着量子力学研究的不断深入以及计算性能的日益强大,该方法可以在更大尺度上进行复杂体系的计算,以其为基础的油藏、页岩油气藏CO_(2)-EOR机理等研究将会取得较大的突破。

自适应分块的改进最小费用网络流解缠算法

相位解缠是进行精确差分干涉测绘的关键步骤,在相位解缠算法中,最小费用网络流(MCF)是当前常用的算法,该算法具有精度高、限制残差点误差扩散、优先将误差限制在低相干区域的优点,但随着残差点数量的增多,其计算效率也随之降低。改进的MCF算法通过对其做分块,有效提升了算法效率,但块尺寸的选取影响最后的准确度与效率。本文提出一种自适应分块的改进MCF解缠算法,通过自适应寻优的方式选取合适的分割块,将相干性较高的点集中在同一块内,使得在准确度不受过多影响的情况下有效地提升算法效率。

多功能泵保护阀旁路设计

离心泵的最小流量控制通常使用手动阀门操作控制或限流孔板控制,手动操作控制流量误差大,而且耗时费力;限流孔板控制流量不能实现关断,造成资源浪费;设计成自动调节控制,需要增加一套自动控制回路和调节阀,造价成本较高。然而,集四种功能于一体的多功能泵保护阀,不仅克服了前三种控制方式的不足,而且兼顾了止回阀和流量调节的功能。本文详细介绍了多功能泵保护阀在各种工况下的良性运行,以及它的使用方法、工作原理、使用功能、汽蚀的产生和消除。通过流体仿真分析、重难点计算和静密封试验,充分验证了用多功能泵保护阀替代离心泵最小流量控制的可行性和可靠性。

基于低频采集数据的城市道路车辆轨迹重构

在进行城市道路交通流量调查及部分重要路网节点、交叉口交通数据采集时,采用低频数据收集方式会使车辆轨迹匹配精度低、交通流量数据误差大。通过研究隐式马尔可夫理论及最小费用最大流模型,提出一种车辆轨迹重构方法。该方法利用多源数据融合技术以及地理信息定位匹配技术,对无检测器路段缺失的各项交通基础数据进行合理的演进推算,为车辆轨迹重构研究提供重要的数据支撑。利用成都市某区域出租车的高频轨迹点位数据集进行验证。结果表明,利用车辆低频轨迹点位进行轨迹重构的完全覆盖率达到了89.4%,验证了所提出的车辆轨迹重构方法的有效性及可行性。

基于最小分支剩余容量的矿井通风网络极值流算法

为计算矿井最大通风量,针对最短增广链算法随机选取增广链,造成增广链缺失和极值流偏小的问题,提出一种基于最小分支剩余容量的矿井通风网络极值流算法。该算法在选取增广链时,选择中间分支剩余容量最小的增广链进行增广;每次增广完毕后,优先选择与增广完毕的增广链包含相同分支的增广链进行下一次增广。利用Excel Solver解算模型与BA无标度随机网络进行仿真实验,结果表明该算法比最短增广链算法解算时间短,且避免了增广链缺失。研究结论为矿井最大通风量的计算提供理论参考。

Relationship between Formation Water Rate,Equivalent Penetration Rate and Volume Flow Rate of Air in Air Drilling

Formation water invasion is the most troublesome problem associated with air drilling. However,it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during air drilling. Formation water could be circulated out of the wellbore through increasing the gas injection rate. In this paper,the Angel model was modified by introducing Nikurade friction factor for the flow in coarse open holes and translating formation water rate into equivalent penetration rate. Thus the distribution of annular pressure and the relationship between minimum air injection rate and formation water rate were obtained. Real data verification indicated that the modified model is more accurate than the Angel model and can provide useful information for air drilling.

Supersonic Two-Dimensional Minimum Length Nozzle Design at High Temperature. Application for Air

When the stagnation temperature of a perfect gas increases, the specific heat ratio does not remain constant any more, and start to vary with this temperature. The gas remains perfect, its state equation remains always valid, except it will name in more calorically im-perfect gas or gas at High Temperature. The goal of this work is to trace the profiles of the supersonic Minimum Length Nozzle with centered expansion when the stagnation temperature is taken into account, lower than the threshold of dissociation of the molecules and to have for each exit Mach number several nozzles shapes by changing the value of the temperature. The method of characteristics is used with a new form of the Prandtl Meyer function at high temperature. The resolution of the obtained equations is done by the second order of finite differences method by using the predictor corrector algorithm. A study on the error given by the perfect gas model com-pared to our model is presented. The comparison is made with a calorically perfect gas for goal to give a limit of application of this model. The application is for the air.

Minimum Cost of Capacity Expansion for Time-Limited Transportation Problem On-Demand

The minimum cost of capacity expansion for time-limited transportation problem on-demand (MCCETLTPD) is to find such a practicable capacity expansion transportation scheme satisfying the time-limited T along with all origins’ supply and all destinations’ demands as well as the expanding cost is minimum. Actually, MCCETLTPD is a balance transportation problem and a variant problem of minimum cost maximum flow problem. In this paper, by creating a mathematical model and constructing a network with lower and upper arc capacities, MCCETLTPD is transformed into searching feasible flow in the constructed network, and consequently, an algorithm MCCETLTPD-A is developed as MCCETLTPD’s solution method basing minimum cost maximum flow algorithm. Computational study validates that the MCCETLTPD-A algorithm is an efficient approach to solving the MCCETLTPD.

多主体博弈共赢的电动汽车充电桩共享方法

充电桩共享是缓解车桩配置不平衡的一种可行方案。该文综合考虑配电网、电动汽车(EV)用户、充电桩、聚合商四方主体利益,提出一种基于主从博弈的充电桩共享方法。给出了基于车桩匹配中心的充电桩共享多主体博弈框架,并分别建立四个主体的成本和效益函数;提出考虑节点边际电价的车-桩-网三阶段主从博弈经济调度模型,并给出基于静态不完全信息博弈的充电桩及其聚合商最优报价策略和基于最小费用最大流的车桩匹配策略;结合图论最短路最大流理论,提出基于Ford-Fulkerson最大流算法的主从博弈双层迭代求解方法。算例分析表明,该文所提方法能有效提升四方主体经济效益、车桩匹配成功数和充电桩使用率。

Performance Analysis of Multi-Hop Wireless Link under Maximum Flow Algorithm

To enhance link capacity of a wireless link one or more repeater is used between the sender and the receiver. Recent literature deals with multiple parallel links to enhance throughput instead of conventional single path. In case of a multidirectional and multi-hop wireless network, the selection of link of maximum signal to noise ratio (SNR) does not guarantee the maximum throughput. In this paper, we use augmenting path of Ford-Fulkerson algorithm in detection of maximum flow from sender to receiver. To reduce the process time at the sending node, minimum-cut theorem is used to determine maximum flow like power flow of previous work. Using the maximum flow algorithm, we obtain the capacity of multi-hop wireless link higher than the conventional theorem. The concept of the paper is applicable in MANET (Mobile Ad-hoc Network), WSN (Wireless Sensor Network) and CRN (Cognitive Radio Network).