Resilience Assessment of Water Resources System

The resilience perspective, which emphasizes the integrated, systemic concept of human and nature interactions, is increasingly used as an approach for understanding the dynamic of social-ecological system. As the water resources system (WRS) is a social-ecological system, resilience thinking such as Holling??s adaptive cycle has been adopted as a fundamental unit for understanding the water resources system dynamics in this paper. In the adaptive cycle of WRS, the likelihood shift among different phases largely depends on resilience value; and a quantitative method for estimating the resilience of WRS is proposed. The method is related to the degree of change and characteristics of the WRS, and has been applied to identify the phase of WRS in every city in Zhejiang province, China. The results of resilience assessment have also been discussed in terms of adaptive cycle.     

Configuration and Recent Field installations of LV-Converter Based Energy Storage System

Energy storage plays an increasingly important role in modem power systems. It can add value to power systems in various aspects. This paper discusses possible energy storage system （ESS） applications and their benefits to power systems. The system configuration, converter design, and recent field installations of an LV converter based ESS are presented.     

Agent-Based Knowledge Analysis Framework in Disaster Management

Disaster Management (DM) is a complex set of interrelated activities. The activities are often knowledge-intensive and time sensitive. Timely sharing of the required knowledge is critical for DM. For recurring disasters (e.g. floods), developed countries tend to have dedicated document repositories of Disaster Management Plans (DISPLANs) that can be accessed as needs arise. However, accessing the appropriate plan in a timely manner, and sharing activities between plans, often requires significant domain knowledge and intimate understanding of the plans in the first place. This paper introduces an Agent-Based (AB) knowledge analysis method to convert DISPLANs into a collection of knowledge units that can be stored into a unified repository. The repository of DM actions then enables the mixing and matching of knowledge between different plans. The repository is structured as a layered abstraction according to Meta Object Facility (MOF). We use the flood DISPLANs plans used by SES (State Emergency Service), an authoritative DM agency in New South Wales (NSW) State of Australia (hereinafter referred to as SES NSW) to illustrate and give a preliminary validation of the approach. It is illustrated by using displans along the flood-prone Murrumbidgee river in central NSW.     

Comparative Study of Three Updating Procedures for Real-Time Flood Forecasting

Accurate real-time flood forecasting is essential for flood control and warning system, reservoir operation and other relevant water resources management activities. The objective of this study is to investigate and compare the capability of three updating procedures, namely autoregressive (AR) model, recursive least-squares (RLS) model and hydrologic uncertainty processor (HUP) in the real-time flood forecasting. The Baiyunshan reservoir basin located in southern China was selected as a case study. These three procedures were employed to update outputs of the established Xinanjiang flood forecasting model. The Nash-Sutcliffe efficiency (NSE) and Relative Error (RE) are used as model evaluation criteria. It is found that all of these three updating procedures significantly improve the accuracy of Xinanjiang model when operating in real-time forecasting mode. Comparison results also indicated that the HUP performed better than the AR and RLS models, while RLS model was slightly superior to AR model. In addition, the HUP implemented in the probabilistic form can quantify the uncertainty of the actual discharge to be forecasted and provide a posterior distribution as well as interval estimation, which offer more useful information than two other deterministic updating procedures. Thus, the HUP updating procedure is more promising and recommended for real-time flood forecasting in practice.     

水电站发电对河流水环境容量的影响分析

清理水库(水电站)对河流水环境容量的影响,对实施排污权交易、环境补偿和保护水环境等方面有重要作用,根据常用的零维、一维水环境容量计算模型和能量守恒定律,推导出水电站修建前后对河流水环境容量影响的定量判别关系式,并以广东省东江干流的12个梯级水电站和3座水库为研究对象,分析了各水库、水电站发电对东江流域水环境容量的影响。结果表明,除龙潭、枕头寨和柳城3个梯级水电站外,其余9个水库、水电站均增加了东江流域水环境容量。     

鞍山地区铁矿石选矿厂技术改造的探讨

介绍了鞍山地区铁矿选矿厂的现状及其与国外先进水平的差距,并对其 改造及发展提出了建议。     

两种瑞利衰落信道模型的研究

信道建模和仿真是研究移动无线通信中各种技术和网络规划的基础和关键.在给出的移动无线信道建模的数学参考模型基础上,分析了传统Jakes模型中存在的不足.后人因此提出了两种改进型的模型:Pop模型和Zheng模型.将两种改进型模型进行了理论上的对比,区分两者是如何分别引入随机相位来改善原有模型的,还对两种模型进行了MATLAB仿真研究,对比两种模型的性能.研究表明两种模型都能通过随机相位的引入解决Jakes模型中的稳定性问题,但是Zheng模型的性能更好且更容易实现.Zheng模型对于瑞利衰落信道的建模具有更大的价值.     

Optimal Operation of Multi-reservoir Systems Considering Time-lags of Flood Routing

Operations of multi-reservoir systems are nonlinear and high-dimensional problems, which are difficult to find the optimal or near-optimal solution owing to the heavy computation burden. This study focuses on flood control operation of multi-reservoir systems considering time-lags caused by Muskingum flood routing of river channels. An optimal model is established to jointly minimize the flood peak on the downstream flood control station for the multi-reservoir systems. A hybrid algorithm, Progressive Optimality Algorithm and Successive Approximation (POA-SA), is improved to solve the multi-reservoir operation model by modifying the POA. The POA-SA uses the DPSA to reduce the spatial dimensionality due to the multiple reservoirs, and adopts an improved POA to alleviate the temporal dimensionality caused by the time-lags of the Muskingum flood routing. Linear programming is then implemented to verify the solution of the POA-SA method with a linear approximation of the discharge capacity curve. The multi-reservoir systems of China’s Xijiang River is selected for a case study. Results show that the flood peak of Wuzhou station can be averagely decreased by 6730 m³/s (12.8 %) for the 100-year return period floods, indicating that the proposed method is efficient to operate the multi-reservoir systems and resolve the time-lags issues.     

DC-DC低功耗限流电路的设计

设计了一种用于升压型DC-DC转换器的限流电路,可以防止芯片内部的功率开关管遭受大电流的冲击。该电路把电流流过开关管产生的压降与参考电流流过参考管产生的压降相比较,输出电流限制信号,克服了传统限流电路功耗大等缺陷。还设计了一种低功耗的动态参考电流源,其软启动功能能够减小输出电压的过冲。Spectre仿真结果表明,限流电路有效限制了开关管的最大电流,满足设计要求。     

Uncertainty Analysis of Bivariate Design Flood Estimation and its Impacts on Reservoir Routing

The bivariate hydrological quantile estimation may inevitably induce large sampling uncertainty due to short sample size. It is crucial to quantify such uncertainty and its impacts on reservoir routing. In this study, a copula-based parametric bootstrapping uncertainty (C-PBU) method is proposed to characterize the bivariate quantile estimation uncertainty and the impact of such uncertainty on the highest reservoir water level is also investigated. The Geheyan reservoir in China is selected as a case study. Four evaluation indexes, i.e. area of confidence region, mean horizontal deviation, mean vertical deviation and average Euclidean distance, are adopted to quantify the quantile estimation uncertainty. The results indicate that the uncertainty of quantile estimation and the highest reservoir water level increases with larger return period. The 90% confidence interval (CI) of highest reservoir water level reaches 1.56 m and 2.52 m under 20-year and 50-year JRP respectively for the sample size of 100. It is also indicated that the peak over threshold (POT) sampling method contribute to uncertainty reduction comparing with the annual maximum (AM) method. This study could provide not only the point estimator of design floods and corresponding design water level, but also the rich uncertainty information (e.g. 90% confidence interval) for the references of reservoir flood risk assessment, scheduling and management.