明清时期雷州地区的学校教育与“风水工程”

明清时期,雷州地区兴建了不少"风水工程"。这些"风水工程"大多数与学校教育或科举考试有关。这些"风水工程"能给落后地区的人们(尤其是士人)带来莫大的心理慰藉。古代雷州士人最迫切的愿望是科举及第,平步青云;而官员们营建的一项项"风水工程",正是赠送给每位士人甜美的"心灵鸡汤"、丰盛的"精神宴席",同时也是封建官员争取士民支持的"民心工程"。

Effects of windbreak width in wind direction on wind velocity reduction

The variations of drag force acting on the windbreak and the bulk drag coefficients for different windbreak widths were studied experimentally in the Eiffel-type non-circulating wind tunnel at the Hydraulic Engineering Laboratory, Saitama University, Japan, to elucidate the effects of windbreak width in the wind direction on wind velocity reduction behind a windbreak. The variations of flow field for different windbreak widths were studied numerically by using the two-dimensional Reynolds-averaged Navier-Stokes （RANS） equation with a k-c turbulence closure model. Results show that the total drag force to wind increased with increasing windbreak width, but the bulk drag coefficient decreased slightly. The relationship between the bulk drag coefficient Cd and the windbreak width W and height H can be presented by the equation of Ca= kd （W/H）^-b （kd, b： constants）. The result of the numerical simulation shows that the windbreak width greatly affects the location and the value of the minimum wind velocity. The wind velocity decreased by 15%-22% as the windbreak width increased.

The planning and comprehensive utilization of Three Gorges Project

As the most significant water project,the Three Gorges Project (TGP) was designed to take care of multiple objectives for water utilization such as flood control,power generation and navigation.The implementation of the project improved the flood safety level of Jingjiang reach to more than 100-year return period,which reduced greatly the flood risk at the mid-lower reaches of Changjiang River,produce huge quantity of energy for the central,east and south China,and improved significantly the navigation conditions of Chuanjiang River.Meanwhile,the operation of the TGP in dry season which compensate the downstream water resources,will as well deepen the navigation channel and thus improve the navigation conditions in the middle river reach.With the increasing demands raised from various aspects of the society,new requirements will be made for the TGP for the purpose of harnessing,development and protection of the Yangtze River Basin.Therefore,it will be a long-term task for the operation of TGP on how to optimize the water resources utilization and implement an effective operation.

Operation safety risk analysis method of hydropower project considering time-dependent effect

In order to consider the time-dependent characteristic of risk factors of hydropower project,the method of stochastic process simulating structure resistance and load effect is adopted.On the basis of analyzing the structure characteristics and mode of operation,the operation safety risk rate assessment model of hydropower project is established on the comprehensive application of the improved analytic hierarchy process,the time-dependent reliability theory and the risk rate threshold.A scheme to demonstrate the time-dependent risk rate assessment method for an example of the earth-rock dam is particularly implemented by the proposed approach.The example shows that operation safety risk rate is closely related to both the service period and design standard;considering the effect of time-dependent,the risk rate increases with time and the intersection of them reflects the technical service life of structures.It could provide scientific basis for the operation safety and risk decision of the hydropower project by predicting the trend of risk rate via this model.

Insurance ratemaking method for risk of construction diversion project

Based on analyzing risk factors of diversion project,synthetic risk rate and engineering insurance period,the frequency and distribution law of loss are researched on the grounds that foundation pit is submerged after diversion project ceases to be effective.And then,the standpoint that these total loss is subject to non-homogeneous compound Poisson processes is put forward.Furthermore,the collective risk model of the total loss about engineering insurance is established on the basis of construction diversion project risk.Ultimately,insurance ratemaking method for construction engineering risk and its mathematical expression are presented,which provides theoretical method for the insurance ratemaking of hydropower engineering to some extent.

Assessment of Risk of TBM Jamming during Construction of Hydro Tunnel in Belgrade

A hydro tunnel in Serbia＇s capitol Belgrade is currently constructed using EPB TBM （earth pressure balance tunneling machine）. To assess the risk of TBM jamming, an analysis is made including calculation of expected ground pressures on the machine and critical frictions and pressures along the route, which could stop the advance due to limitations of the machine. The ground pressures were calculated using 2D plain strain analytical and numerical methods, and using 2D＋ plain strain axisymmetrical numerical method to simulate effects of TBM advance, effects of deformations in front of TBM and effects of rigidity changes in area of TBM shield tail where ground abruptly looses contact with the shield and could additionally deform toward the concrete liner. Calculated deformations and stresses varied along the TBM and concrete liner, with prominent concentrations around the cutter head and TBM shield tail. The results of analytical and numerical calculations were compared and combined to construct diagrams of expected ground pressures on TBM along the tunnel route, and diagrams of critical frictions that may cause the jamming. Based on this analysis and ongoing measurements of ground pressures on TBM, recommendations have been made on excavation regimes, and additional investigations in front of TBM. So far a relatively fair match of the predicted and measured ground pressures on TBM is observed.

State Modeling Based Prediction of Torsional Resonances for Horizontal-Axis Drive Train Wind Turbine

This paper focuses on the state space modeling approach and output torques prediction of torsional vibrations for variable speed wind turbines. The multi-body system model under study is mainly comprised of a wind turbine, a three stage planetary gear box and an induction generator. The masses-springs approach of shaft system differential equations is developed from Newton＇s law and Lagrange formulas. For an easy comprehension for electrical engineers and tutorial purpose, an electrical equivalent circuit of the system is proposed by using mechanical and electrical components similarities. Extensive numerical simulations are performed to investigate system mechanical resonances and impacts of damping factors on the system dynamic and stability.

The Evaluation of the Integrated Risk for the South-to-North Water Transfer Project Using the Bayesian Network Theory

南水北调工程是目前我国最大的调水工程。随着工程的建设和运行,由不确定性问题引起的风险问题越来越受到关注,工程运行的风险分析也摆在管理者的面前,如何识别、评估、降低和控制风险的发生成为南水北调工程运行中的一个重要问题。本文首次将贝叶斯网络理论引入到南水北调综合风险分析中,选取东线工程宝应抽水泵站为研究对象,利用贝叶斯网络推理功能得出宝应站运行综合风险发生的概率为0.025%,风险发生的等级为"较低"。利用情景分析的方法,得出在影响综合风险的因素中,泵站的管理维护状况条件改变时,综合风险变化最大,因此需要予以重点关注。