检索结果-南通市图书馆

CASCADIC MULTIGRID METHOD FOR THE MORTAR ELEMENT METHOD FOR P1 NONCONFORMING ELEMENT

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2005年第4期23卷 425-440页

作者： Chun-jia bi Dan-hui Hong Department of Mathematics Yantai University Shandong 264005 China Institute of Mathematics Fudan University Shanghai 200433 China

In this paper, we consider the cascadic multigrid method for the mortar P1 nonconforming element which is used to solve the Poisson equation and prove that the cascadic conjugate gradient method is accurate with optim... 详细信息

关键词： Mortar P1 nonconforming element Cascadic multigrid method

Pricing Variance Swaps Under Stochastic Volatility with an Ornstein-Uhlenbeck Process

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2015年第6期28卷 1412-1425页

作者： jia Zhaoli bi Xiuchun ZHANG Shuguang School of Mathematics Hefei University of Technology Department of Statistics and Finance University of Science and Technology of China

Pricing variance swaps under stochastic volatility has been an important subject pursued recently. Various approaches have been proposed, mainly due to the substantially increased trading activities of volatility-related derivatives in the past few years. In this note, the authors develop analytical method for pricing variance swaps under stochastic volatility with an Ornstein-Uhlenbeck(OU) process. By using Fourier transform algorithm, a closed-form solution for pricing variance swaps with stochastic volatility is obtained, and to give a comparison of fair strike value based on the discrete model, continuous model, and the Monte Carlo simulations.

关键词： Closed-form solution Ornstein-Uhlenbeck process stochastic volatility variance swaps

Decentralized Robust Energy Management of Multi-area Integrated Electricity-gas Systems

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2021年第6期9卷 1478-1489页

作者： Nan jia Cheng Wang Wei Wei Tianshu bi IEEE State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Department of Electrical Engineering Tsinghua University

This paper proposes a fast and decentralized solution methodology for the robust operation of multi-area integrated electricity-gas systems(M-IEGSs).A deterministic reformulation is obtained for the two-stage robust model by applying the linear decision rule based electrical reserve utilization scheme as well as regulating the distributed gas *** linear approximations are developed for the nonconvex Weymouth equation in the gas network to determine the gas flow *** penalty convex-concave procedure(P-CCP)is then adopted to refine a feasible local optimum for the nonconvex model with an acceleration *** decentralized decision-making is enabled by the alternating direction multipliers method(ADMM).The convergence as well as computation performance of the overall solution procedure can be guaranteed as only convex optimizations are *** results validate the effectiveness of the proposed methods as well as the benefits of the proposed convex programing based solution procedure.

关键词： Convex optimization decentralized robust optimization energy management linear approximation integrated electricity-gas system

Robustness analysis of underground powerhouse construction simulation based on Markov Chain Monte Carlo method

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2016年第2期59卷 252-264页

作者： ZHONG DengHua bi Lei YU jia ZHAO MengQi State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University

Scheduling is a major concern in construction planning and management, and current construction simulation research typically targets the shortest total duration. However, uncertainties are inevitable in actual construction, which may lead to discrepancies between the actual and planned schedules and increase the risk of total duration delay. Therefore, developing a robust construction scheduling technique is of vital importance for mitigating disturbance and improving completion probability. In the present study, the authors propose a robustness analysis method that involves underground powerhouse construction simulation based on the Markov Chain Monte Carlo(MCMC) method. Specifically, the MCMC method samples construction disturbances by considering the interrelationship between the states of parameters through a Markov state transition probability matrix, which is more robust and efficient than traditional sampling methods such as the Monte Carlo(MC) method. Additionally, a hierarchical simulation model coupling critical path method(CPM) and a cycle operation network(CYCLONE) is built, using which construction duration and robustness criteria can be calculated. Furthermore, a detailed measurement method is presented to quantize the robustness of underground powerhouse construction, and the setting model of the time buffer is proposed based on the MCMC method. The application of this methodology not only considers duration but also robustness, providing scientific guidance for engineering decision making. We analyzed a case study project to demonstrate the effectiveness and superiority of the proposed methodology.

关键词： underground powerhouse construction schedule simulation model MCMC method robustness

A review of single phase adaptive auto-reclosing schemes for EHV transmission lines

在线全文

学校读者我要写书评

暂无评论

Protection and Control of Modern Power Systems 2019年第1期4卷 217-226页

作者： Waqar Ahmad Khan Tianshu bi Ke jia State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing102206People’s Republic of China Faculty of Engineering Lahore Leads UniversityLahorePunjabPakistan

Statistics shows that transients produced by lightning or momentary links with external objects, have produced more than 80% of faults in overhead lines. Reclosing of circuit breaker (CB) after a pre-defined dead time is very common however reclosing onto permanent faults may damage the power system stability and aggravate severe damage to the system. Thus, adaptive single-phase auto-reclosing (ASPAR) based on investigating existing electrical signals has fascinated engineers and researchers. An ASPAR blocks CB reclosing onto permanent faults and allows reclosing permission once secondary arc is quenched. To address the subject, there have been many ASPARs techniques proposed based on the features trapped in a faulty phase. This paper presents a critical survey of adaptive auto-reclosing schemes that have hitherto been applied to EHV transmission lines.

关键词： Adaptive auto-reclosing Protection EHV transmission lines Temporary faults Permanent faults

Tunable Luminescence Properties and Elucidating the Electronic Structures of Single-Phase Spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)Phosphors for Warm-White-Lighting

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Renewable Materials 2022年第2期10卷 431-451页

作者： Zun bi Ke jia Yunfei Liu Yinong Lyu State Key Laboratory of Materials–Orient Chemical Engineering College of Materials Science and EngineeringNanjing Tech UniversityNanjingChina jiangsu National Synergetic Innovation Center for Advanced Materials(SICAM) NanjingChina jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites NanjingChina

A series of uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors were prepared via a microwave hydrothermal method by using trisodium citrate dehydrate as *** phase structure,morphology and photoluminescence properties were measured by powder X-ray diffraction,scanning electron microscope and fluorescence spectrometer,*** results show that uniform spherical microcrystals with diameters in the range of 2–4μm are *** the phase and morphology of samples are not significantly changed by doping rare earth(RE^(3+))*** the excitation wavelength of 356 and 365 nm,the samples BaWO 4:0.03Dy^(3+),yTm^(3+)can emit cold white *** order to lower the correlated color temperature(CCT)to get a warm white light,the Eu^(3+)ions were doped into BaWO 4:0.03Dy^(3+),0.01Tm^(3+).Especially,under the excitation of 365 nm,BaWO 4:0.03Dy^(3+),0.01Tm^(3+),0.03Eu^(3+)phosphor shew a bright warm white light with color coordi-nate of(0.4013,0.3629)and CCT of 3288 ***,in the BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors,the energy transfer mechanism among Dy^(3+),Tm^(3+)and Eu^(3+)ions have been discussed and the change of electron structures have been calculated by first-principles *** results shew that the uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors could be favorable candidates in warm white LEDs.

关键词： Barium tungstate microwave hydrothermal method spherical warm white lighting electron structures

HYDRODYNAMIC CHARACTERISTICS AND SEISMIC ANALYSIS OF OFFSHORE CYLINDRICAL STRUCTURE-FLUID-SOIL SYSTEMS

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1991年第3期3卷 79-87页

作者： jia-ju, bi Hong, Zhuang Xiu-ling, Weng Tongi Univ Shangkai China

An analytical method is developed to solve the coupled vibration problem of a vertical elastic circular cylindrical structure founded on homogeneous elastic soil with surrounding fluid. An improved mathematical model is adopted by which not only the structure-fluid interaction but also the influence of soil are considered. The frequency-dependent radiation added mass and hydrodynamic radiation damping are expressed in closed form, and are compared with generalized mass and damping respectively. Their variations with the exciting frequency are studied as well. A discussion of the influences of structure fluid interaction and structure-soil interaction upon hydrodynamic loading is given.

关键词： Computers Applications Fluid Mechanics Foundations Soil Structure Interaction Hydrodynamics Mathematical Models

A voltage resonance-based single-ended online fault location algorithm for DC distribution networks

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2016年第5期59卷 721-729页

作者： jia Ke LI Meng bi Tian Shu YANG Qi Xun State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University

A novel single-ended online fault location algorithm is investigated for DC distribution networks. The proposed algorithm calculates the fault distance based on the characteristics of the voltage resonance. The Prony's method is introduced to extract the characteristics. A novel method is proposed to solve the pseudo dual-root problem in the calculation process. The multiple data windows are adopted to enhance the robustness of the proposed algorithm. An index is proposed to evaluate the accuracy and validity of the results derived from the various data windows. The performances of the proposed algorithm in different fault scenarios were evaluated using the PSCAD/EMTDC simulations. The results show that the algorithm can locate the faults with transient resistance using the 1.6 ms data of the DC-side voltage after a fault inception and offers a good precision.

关键词： protection fault location DC distribution VSC voltage resonance Prony's method

Insight into the ammonia torrefaction and pyrolysis system of cellulose:Unraveling the evolution of chemical structure and nitrogen migration mechanism

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2023年第3期78卷 135-147,I0005页

作者： Shanjian Liu An Zhao jia Liu Mengqian Yin Fupeng Huang Dongmei bi School of Agricultural Engineering and Food Science Shandong University of TechnologyZibo 255000ShandongChina

This study aimed to investigate the mechanism of nitrogen doping,migration,and conversion during ammonia torrefaction and also explore the evolution law of the chemical structure of *** results showed that the ammonia torrefaction pretreatment could significantly optimize the distribution of nitrogen and oxygen elements in *** carbon skeleton first captured the active nitrogenous radicals to form-NHn-N,and pyridine-N and pyrrole-N originated from the conversion *** existence of C=O played a major role in the immobilization of *** nitrogen in bio-oil exists mainly in the form of five-and six-membered *** correlation analysis showed that the main precursors for the formation of nitrogenous heterocyclic compounds were five-membered Oheterocyclic ***,the product distribution characteristics in the torrefaction-pyrolysis systems were summarized,and the nitrogen doping and conversion mechanisms were *** study expanded the boundaries of cellulose pretreatment and the production of high-value chemicals.

关键词： Ammonia torrefaction Cellulose Nitrogenous compounds Structure evolution Nitrogen migration