Machine-learning paradigms for selecting ecologically significant input variables

Harmful algal blooms, which are considered a serious environmental problem nowadays, occur in coastal waters in many parts of the world. They cause acute ecological damage and ensuing economic losses, due to fish kills and shellfish poisoning as well as public health threats posed by toxic blooms. Recently, data-driven models including machine-learning (ML) techniques have been employed to mimic dynamics of algal blooms. One of the most important steps in the application of a ML technique is the selection of significant model input variables. In the present paper, we use two extensively used ML techniques, artificial neural networks (ANN) and genetic programming (GP) for selecting the significant input variables. The efficacy of these techniques is first demonstrated on a test problem with known dependence and then they are applied to a real-world case study of water quality data from Tolo Harbour, Hong Kong. These ML techniques overcome some of the limitations of the currently used techniques for input variable selection, a review of which is also presented. The interpretation of the weights of the trained ANN and the GP evolved equations demonstrate their ability to identify the ecologically significant variables precisely. The significant variables suggested by the ML techniques also indicate chlorophyll-a (Chl-a) itself to be the most significant input in predicting the algal blooms, suggesting an auto-regressive nature or persistence in the algal bloom dynamics, which may be related to the long flushing time in the semi-enclosed coastal waters. The study also confirms the previous understanding that the algal blooms in coastal waters of Hong Kong often occur with a life cycle of the order of 1–2 weeks.     

Dynamic equivalent method of interconnected power systems with consideration of motor loads

The existing equivalent methods usually only deal with static load models and neglect the dynamic characteristics of loads such as induction motors.This paper presents a dynamic equivalent method which considers motor dynamics.At first,the clustering criterion of motor loads is given.The motors with similar dynamic characteristics are classified into one group.Then,reduction of motors in the same group is carried out.Finally,parameters of the equivalent motor are calculated and the equivalent system is thus...     

Study on early warning index of spatial deformation for high concrete dam

Owing to the deficiency in early warning for high concrete dam,a formula was established to characterize the deformation behavior of high concrete dam as a whole.The early warning index of spatial deformation was calculated by low probability principle on the basis of the deformation entropy formula proposed.The steps were as follows.Firstly,the probability method was utilized to define the degree of order and degree of chaos for each survey point.Secondly,the weight distribution among the survey points was...     

泡沫铝负载氧化铈的制备及其除氟性能研究

以六水合硝酸铈为铈源、六次甲基四胺为沉淀剂,通过水热法制备了氧化铈(CeO2)粉末和泡沫铝负载氧化铈复合体。环境扫描电镜(ESEM)观察表明成功实现了泡沫铝负载氧化铈,且氧化铈在泡沫金属上不易脱落。透射电子显微镜(TEM)观察表明氧化铈(CeO2)粉末颗粒的粒径为5～10nm,呈立方块状,选区电子衍射为多晶环。研究了pH值和时间对氧化铈及泡沫铝负载氧化铈复合体除氟性能的影响,经理论计算及实验数据拟合,结果表明CeO2及复合体除氟是在其表面的羟基同氟离子发生可逆交换吸附去除氟离子,属于交换吸附模型。     

Application of strength reduction method to dynamic anti-sliding stability analysis of high gravity dam with complex dam foundation

Considering that there are some limitations in analyzing the anti-sliding seismic stability of dam-foundation systems with the traditional pseudo-static method and response spectrum method,the dynamic strength reduction method was used to study the deep anti-sliding stability of a high gravity dam with a complex dam foundation in response to strong earthquake-induced ground action.Based on static anti-sliding stability analysis of the dam foundation undertaken by decreasing the shear strength parameters of ...     

电力系统混合优化的模拟进化方法

电力系统中有许多混合优化问题,采用常用方法求解难以奏效,而模拟进化方法是一种新型有效的优化方法,文中提出模拟进化方法中处理混合优化问题的两种办法,即离散变量连续化及连续变量离散化,并将其应用电力系统功率,电容器组的优化问题,结果表明所提方法是可行的。     

Optimal allocation of water resources in large river basins: I. Theory

The major purpose of this paper is to present the useful techniques in the optimal allocation of water resources (OAWR) and to demonstrate using water resources applications how these methods can be conveniently employed in practice for systematically studying both simple and complex water resources problems. Formal modelling techniques in multiobjective decision-making provide many benefits to professionals working in water resources and elsewhere. A new Large-system Hierarchical Dynamic Programming (LHDP) method to solve the model can be carried out to ascertain the consequences of meaningful parameter changes upon the optimal or compromise solution.As a case study, the techniques and methods are applied to the OAWR of the Yellow River Basin (YRB) of China. The next paper shares with the reader recent research results on the OAWRYRB.Notation L _i inflows from the trunk stream in the subregioni. - S _i run-off volume of the river sectioni. - Q _i net inflows of intervals in the subregioni. - W _i volumes of water drawn the trunk stream ofi into subdistricti. - H _i volumes of water returning to the trunk stream in the subdistricti. - B _i(W _i) the maximum net benefits (in hundred million yuan) from the annual-water consumption ofW _iin subregioni. - W _ik the annual-water consumption (in hundred million m³) of sectorK in subregioni, k = 1, 2, 3, 4. - B _ik(W _ik the maximum net benefits (in hundred million yuan) from the annual consumptionW _ikof sectork in subregioni. - BS _i(S _i) the maximum net benefits (in hundred million yuan) obtained from the optimal allocation of the run-off volumeS _iof river trunki among different sectors within the months of a year.     

浅谈信息科技化在农村社会管理的作用

随着社会的进步和时代的发展,信息科技化已经渗透进人们生活的方方面面。在农村社会管理方面,信息科技化同样能够起到重要的作用。农村社会管理应该时时刻刻保持先进性,要与社会发展同时进步,甚至可以在一定程度上推进社会的发展。加强信息科技化在农村社会管理中的作用,可以很好的将社会管理提高到一个新的发展层面。本文重点探究信息科技化在农村社会管理的作用和发展应用效果,希望能够为推进农村社会管理提供参考。     

论洪灾保险

洪灾保险是非工程防洪措施中的一项重要内容，对维护受灾地区经济的可持续发展和生活保障有着重要的意义，在我国这样一人洪涝灾害频繁、防洪能力偏低的国家，迫切需要依照我国国情，开展洪灾保险业务。洪灾保险应遵循风险大量原则、风险分散原则和保费合理原则，现一般采用危险区域法、期望损失法或洪灾损失法进行保险费用计算，危险区域法是一种比较科学、符合洪灾保险特点的计算方法，应用中可以针地其缺点，改用保险费率代替保险