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基于变权重非线性安全度的梯级防洪库容分配方法研究

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中国农村水利水电 2024年第7期 45-52,59页

作者：劳嘉鹏李英海王永强曾志强余果三峡大学水利与环境学院湖北宜昌443002 水电工程施工与管理湖北省重点实验室(三峡大学) 湖北宜昌443002 长江科学院水资源综合利用研究所湖北武汉430010 智慧长江与水电科学湖北省重点实验室(中国长江电力股份有限公司) 湖北宜昌443000

梯级水库群防洪库容的合理分配与有效利用对汛期水库群防洪减灾和综合效益的发挥起到至关重要的作用。针对梯级水库在防洪库容分配过程中,各水库对整体防洪安全影响的重要程度差异性缺乏有效区分方法,进而导致防洪库容分配不合理的问题... 详细信息

梯级水库群防洪库容的合理分配与有效利用对汛期水库群防洪减灾和综合效益的发挥起到至关重要的作用。针对梯级水库在防洪库容分配过程中,各水库对整体防洪安全影响的重要程度差异性缺乏有效区分方法,进而导致防洪库容分配不合理的问题,将水库非线性安全度与兼顾水库入库流量、设计防洪库容大小、泄流至防洪控制站传播时间等特征的变权重相结合,提出基于变权重非线性安全度的水库防洪安全度计算方法,同时,考虑梯级各水库和下游防洪控制站的安全,以梯级整体防洪安全度最大和下游防洪控制站超标洪量最小为目标,构建基于安全度的梯级防洪库容优化分配模型,采用差分进化算法对模型进行求解,实现防洪库容的最优分配。将该方法应用于金沙江下游乌东德、白鹤滩、溪洛渡、向家坝四库梯级防洪库容分配实例,结果表明该方法相较于其他方法,可在不降低梯级整体防洪效果的前提下,描述各水库权重的动态变化过程,通过增加乌东德和白鹤滩水库防洪库容的使用,以减小溪洛渡和向家坝水库防洪库容的使用,使梯级整体在调度期的防洪安全度达到最大。该方法可反映各水库在梯级防洪中重要程度的差异性,实现水库间防洪库容的科学管理与合理分配,为水库防洪优化调度科学决策提供依据。

关键词：防洪库容分配非线性安全度变权重梯级水库金沙江下游

High Refractive Index without Absorption in a Ladder-Type System

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Chinese Physics Letters 2014年第3期31卷 58-61页

作者： zeng zhi-qiang HOU Bang-Pin LIU Fu-Ti SHAO Ju-Xiang School of Physics and Electronic Engineering Yibin University Yibin 644000 Computational Physics Key Laboratory of Sichuan Province Yibin University Yibin 644000 School of Physics and Electronic Engineering Sichuan Normal University Chengdu 610066

A three-level ladder-type system with vacuum-induced coherence and incoherent pumping is studied to obtain a high refractive index without absorption. It is shown that the enhancement of the refractive index without absorption can be accomplished by choosing the proper values of the incoherent pumping, the angle between the two dipole moments, the probe detuning and the relative phase of the two coherent fields.

关键词： Refractive index

A new way to synthesize ZnS nanoparticles

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Chinese Chemical Letters 2007年第4期18卷 483-486页

作者： Heng zhi zeng Ke qiang Qiu Yuan Yuan Du Wen Zhang Li College of Chemistry and Chemical Engineering Central South University Changsha 410083 China

ZnS nanoparticles were prepared with normal ZnO and Na2S by solid-liquid chemical reaction under ultrasonic condition and characterized by XRD, TEM, SEM, IR and TG-DTG. The results showed that these particles were good crystal cubic zinc blended with average size of 50 nm, possess good IR transmittance in the range of 400-4000 cm and good thermal stability.

关键词： . Solid-liquid chemical reaction Nano-ZnS Crystal

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基于向量集约简的精简支持向量机

软件学报 2007年第11期18卷 2719-2727页

作者：曾志强高济浙江大学计算机科学与技术学院浙江杭州310027

目前的支持向量集约简法在寻找约简向量的过程中需要求解一个无约束的多参数优化问题,这样,像其他非线性优化问题一样,求解过程需要面对数值不稳定或局部最小值问题.为此,提出了一种基于核聚类的SVM(support vector machine)简化方法.... 详细信息

目前的支持向量集约简法在寻找约简向量的过程中需要求解一个无约束的多参数优化问题,这样,像其他非线性优化问题一样,求解过程需要面对数值不稳定或局部最小值问题.为此,提出了一种基于核聚类的SVM(support vector machine)简化方法.此方法首先在特征空间中对支持向量进行聚类,然后寻找特征空间中的聚类中心在输入空间中的原像以形成约简向量集.该方法概念简单,在简化过程中只需求解线性代数问题,从而解决了现存方法存在的瓶颈问题.实验结果表明,该简化法能够在基本保持SVM泛化性能的情况下极大地约简支持向量,从而提高SVM的分类速度.

关键词：支持向量机约简向量集核聚类原像最佳权值

Radical involved reactive wetting and retarding mechanism of alumina refractory ceramic by molten slags under weak static magnetic field

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Journal of Iron and Steel Research International 2024年第6期31卷 1355-1366页

作者： Sheng-hao Li Ao Huang Fan-bo zeng Hui Peng Hao-ran Wei Xue-chun Huang Sheng-qiang Song Hua-zhi Gu The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

High alumina slag will cause severe corrosion at the interface of alumina refractory,and the wetting behavior of slag is a key factor influencing the corrosion resistance of refractory *** static magnetic field is a promising solution for improvement in the slag resistance of *** wetting of alumina refractory ceramics with different basicities of high alumina slags under a weak static magnetic field was analyzed,given that a weak static magnetic field can affect the corrosion behavior of refractory *** slag S_(3) as an example,when there was an external static magnetic field of 1.0 mT at 1600 ℃,the thickness of calcium aluminate reaction layer at the interface decreased by 36.7%,the denting depth of interface decreased by 35.6%,and the apparent wetting angle increased by 20%.The living radicals and their formation path in oxide melts were verified by first-principles calculation combined with electron paramagnetic resonance spectroscopy *** influence of the flux density of a weak static magnetic field on the wetting behavior of slags was also *** contact angle of the slags increased owing to the inhibitory effect of magnetic field on the radicalinvolved reaction at the interface of the slag and the alumina refractory *** relationships between the magnetic flux density,diffusion coefficient,slag microstructure(hyperfine coupling constant),and contact angle were *** provides a theoretical basis for the field control of radical involved reactive wetting between inorganic oxide slags and solid oxide ceramics.

关键词： Alumina refractory ceramic Molten slag Weak magnetic field effect Reactive wetting Free radical

A comprehensive review on microchannel heat sinks for electronics cooling

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International Journal of Extreme Manufacturing 2024年第2期6卷 133-162页

作者： zhi-qiang Yu Mo-Tong Li Bing-Yang Cao Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084People’s Republic of China

The heat generation of electronic devices is increasing dramatically,which causes a serious bottleneck in the thermal management of electronics,and overheating will result in performance deterioration and even device *** the development of micro-machining technologies,the microchannel heat sink(MCHS)has become one of the best ways to remove the considerable amount of heat generated by high-power *** has the advantages of large specific surface area,small size,coolant saving and high heat transfer *** paper comprehensively takes an overview of the research progress in MCHSs and generalizes the hotspots and bottlenecks of this *** heat transfer mechanisms and performances of different channel structures,coolants,channel materials and some other influencing factors are ***,this paper classifies the heat transfer enhancement technology and reviews the related studies on both the single-phase and phase-change flow and heat *** comprehensive review is expected to provide a theoretical reference and technical guidance for further research and application of MCHSs in the future.

关键词： microchannel heat sink thermal management of electronics microscale heat transfer heat transfer enhancement

Influence of Vanes and Blades on Ingress in Axial Rim Seal for Turbine Stages

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Journal of Thermal Science 2024年第3期33卷 833-846页

作者： REN Ran DU qiang LIU Guang zeng Yanlian XIE Lei Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China National Key Laboratory of Science and Technology on Advanced Light-duty Gas-turbine Beijing100190China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing100190China

Hot gas ingestion refers to the phenomenon of mainstream hot gas flowing into the space cavity of a turbine *** studies have found that mainstream annulus pressure distribution plays an important role in hot gas ingestion,but due to its complexity,the mechanism of the interaction between mainstream flow and hot gas ingestion remains *** paper adopts the URANS method,and three sealing flow rates are considered,named C_(w)=0,C_(w)=500,and C_(w)=*** time-averaged annulus pressure distribution shows that an increase in the sealing flow decreases the pressure value,and the effects of the sealing flow on the pressure distribution of the leading edge of the blade are much more influential than that of the trailing edge of the *** unsteady pressure time-space distribution in the annulus indicates that a time-space tilted distribution of pressure at the rim exits when the sealing flow *** phenomenon is mainly due to the strong feedback mechanism of the sealing flow to the annulus pressure field.A comparison of the pressure and mean radial velocity distribution of the mainstream shows that the ingestion mainly occurs on the blade side,where the pressure is lower than on the vane *** flow characteristics at the wheel rim are analyzed with a sealing flow rate C_(w)=5000,and under these conditions,both pressure-induced ingestion and ingestion caused by a passage vortex can be *** three-dimensional and inertial effects of the mainstream at the wheel rim lead to the generation of separation vortices on the blade side,and the presence of separation vortices leads to ingestion along the blade *** the same time,pressure on the blade side will cause the fluid to have a radial inward flow tendency,which will promote the formation of separation vortices,leading to more serious ingestion in the high-pressure region on the blade *** blade pressure field can be more significant than the vane trailing pressure field in the rim sea

关键词： separation vortex unsteady rim seal the effect of blade on ingestion

Switching,explosion,and chaos of multi-wavelength soliton states in ultrafast fiber lasers

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 82-90页

作者： zhi-zeng Si Yue-Yue Wang Chao-Qing Dai College of Optical Mechanical and Electrical EngineeringZhejiang A&F UniversityLin’an 311300China

Because of the complexity and difficulty of realizing a multi-wavelength soliton state,reports on its internal dynamic characteristics are *** this study,the switching and periodic soliton explosion processes of the multi-wavelength soliton state in a negative dispersion passively mode-locked fiber laser are *** generation of the multi-wavelength soliton state undergoes the process of noise,oscillation,and stable mode-locking,and the splitting and annihilation of solitons with different group velocities directly impact the generation and disappearance of three *** and negative dispersion lead to different group velocities of *** presence and displacement of solitons with different group velocities cause soliton collisions,which lead to soliton explosions.A soliton experiences relative phase oscillation,chaos,and oscillation,as well as convergence and separation before and after an *** an increase in parameters related to pump power,single-soliton oscillation,multi-wavelength solitons,and chaos are found in experiments and simulations,proving the relevance and reliability between simulation and experimental *** work promotes the dynamical study of multi-soliton collisions in nonlinear science and the development of chaos theory in multi-comb lasers.

关键词： multi-wavelength fiber laser soliton explosion chaos state switching real-time dynamics

Precise Asymptotics in Limit Theorems for a Supercritical Branching Process with Immigration in a Random Environment

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Acta Mathematica Sinica,English Series 2024年第8期40卷 1850-1874页

作者： Chun Mao HUANG Rui ZHANG zhi qiang GAO Department of Mathematics Harbin Institute of Technology(Weihai)Weihai 264209P.R.China School of Mathematical Sciences Beijing Normal UniversityBeijing 100875P.R.China

Let(Zn)be a supercritical branching process with immigration in an independent and identically distributed random *** necessary moment conditions,we show the exact convergence rate in the central limit theorem on log Zn and establish the corresponding local limit theorem by using the moments of the natural submartingale and the convergence rates of its *** similar approach and with the help of a change of measure,we also present the so-called integrolocal theorem and integral large deviation theorem to characterize the precise asymptotics of the upper large deviations.

关键词： Branching process with immigration random environment central limit theorem large deviation