检索结果-南通市图书馆

Journal of Systems Science & Complexity 2016年第6期29卷 1658-1682页

作者： gu Ailing LI Zhongfei School of Applied Mathematics Guangdong University of Technology Sun Yat-Sen Business School Sun Yat-Sen University

This paper considers a proportional reinsurance-investment problem and an excess-of-loss reinsurance-investment problem for an insurer,where price processes of the risky assets and wealth process of the insurer are both described by Markovian regime *** target of the insurer is assumed to maximize the expected exponential utility from her terminal wealth with a state-dependent utility *** employing the dynamic programming approach,the optimal value functions and the optimal reinsurance-investment strategies are *** addition,the impact of some parameters on the optimal strategies and the optimal value functions is analyzed,and lots of interesting results are discovered,such as the conclusion that excess-of-loss reinsurance is better than proportional reinsurance is not held in the regime-switching jump-diffusion model.

关键词： Excess-of-loss reinsurance optimal investment strategy proportional reinsurance regime-switching state-dependent utility function.

Kinetics of stripping of gold loaded in DBC organic phase by sodium sulfite

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第1期25卷 1-6页

作者： ZHU Ping gu guobang College of Envirotunent Science and Engineering Shanghai University Shanghai 200072 China Department of Applied Chemistry South China University of Technology Guangzhou 510640 China

The kinetics of stripping of gold loaded in dibutyl carbito （DBC） organic phase by sodittm sulfite was investigated in a Lewis cell. After the stirring speed reached 400 r·min^-1, the reaction of gold stripping conformed with the pseudo-first-order reaction. The stripping rate of gold was in direct proportion to interracial area, concentration of sodittm sulfite and reaction temperature. The experimental results showed that the process of stripping gold was controlled by interfacial chemical reaction, and its activation energy was 36.06 kJ·mol^-1. The kinetics equation was put forward for gold stripping by sodium sulfite.

关键词： kinetics stripping gold Lewis cell

Flow around three rectangular cylinders arranged in connected and separated Y-shape

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2005年第4期21卷 336-341页

作者： Zhifu gu Yan Li Department of Mechanics and Engineering Science Peking UniversityBeijing 100871 China

Characteristics of cross flow around three rectangular cylinders with two aspect ratios of breadth to width arranged in connected and separated Y-shape at various angles of incident flow were studied by means of force measurement in a wind tunnel. Flow visualizations with smoke-wire technique for typical cases were also given. Different types of flow patterns were formed for individual models at different angles of incident flow. From the results of fluctuating velocity measurement in the wake, features of vibration were determined. It shows that as the wind blows along the lines of one limb or rectangular cylinder of the model, oscillation is weak, whereas when the wind blows along the bisector lines of two limbs or cylinders, strong vibration is observed. It is associated with the regular vortex shedding.

关键词： Rectangular cylinders. Vortex-induced vibration Flow visualization Y-shape

Efficient enhancing scheme for TCP performance over satellite-based internet

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2007年第1期18卷 177-182页

作者： Wang Lina gu Xuemai Information Engineering School Beijing Univ. of Science and Technology Beijing 100083 E R. China Communication Research Center Harbin Inst. of Technology Harbin 150001 P. R. China

Satellite link characteristics drastically degrade transport control protocol （TCP） performance. An efficient performance enhancing scheme is proposed. The improvement of TCP performance over satellite-based Interuet is accomplished by protocol transition gateways at each end of a satellite link. The protocol which runs over a satellite link executes the receiver-driven flow control and acknowledgements- and timeouts-based error control strategies. The validity of this TCP performance enhancing scheme is verified by a series of simulation experiments. Results show that the proposed scheme can efficiently enhance the TCP performance over satellite-based Internet and ensure that the available bandwidth resources of the satellite link are fully utilized.

关键词： Geostationary satellites Protocol transition gateway Transport control protocol

A new tool for quantum chaos could be powerful for other problems： an inspiring application to many-body localization

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2017年第10期62卷 669-670页

作者： Yingfei gu Department of Physics Stanford University Stanford CA 94305-4060 USA

Chaos,popularly referred to as the butterfly effect,widely exists in familiar systems such as fluid and *** defining feature of the chaos is the high sensitivity on the initial *** example,in classical mechanics,given... 详细信息

关键词：量子混沌定位应用工具蝴蝶效应经典力学敏感性相空间

Thermophoresis effects on gas-particle phases flow behaviors in entrained flow coal gasifier using Eulerian model

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2017年第6期25卷 712-721页

作者： Chao Dai Fan gu School of Energy and Environment Southeast University Nanjing 210096 China

A numerical model based on the Eulerian–Eulerian two-fluid approach is used to simulate the gasification of coal char inside an entrained flow gasifier. In this model, effects of thermophoresis of coal char particles are thoroughly investigated. The thermophoresis is due to the gas temperature gradient caused by absorpted heat of coal char gasification. This work, firstly, calculates the gas temperature gradient and thermophoretic force at1100 °C,1200 °C,1300 °C and 1400 °C wall temperatures. Then, the changes of particle volume fraction and velocity in the gasifier are studied in the simulation with thermophoresis or not. The results indicate that considering the particle thermophoresis has some effects on the calculation of particle volume fraction in the gasifier, especially at wall temperature of 1400 °C, and the maximum particle volume fraction variance ratio reaches up to 1.38% on wall surface of the gasifier. These effects are mainly caused by large gas temperature gradient along the radial direction of the gasifier. For the particle velocity, the changes are small but can be observable along radial direction of the gasifier, which has good agreement with the distributions of radial gas temperature gradient and thermophoretic force. These changes above may have certain effects on gasification reaction rates in this Eulerian model. So the change of gasification reaction rates in the simulation with thermophoresis or not is studied finally.

关键词： Gasification Thermophoresis Eulerian model Two-phase flow

Influences of interphase on dynamic effective properties of composites reinforced by dispersed spherical particles

在线全文

学校读者我要写书评

暂无评论

Journal of University of Science and Technology Beijing 2006年第3期13卷 256-262页

作者： Peijun Wei Lili gu Applied Sciences School University of Sciences and Technology Beijing Beijing 100083 China Tangshan Iron ＆ Steel Group Co. Ltd Tangshan 063016 China

The influences of interphase on dynamic effective properties of composites reinforced by randomly dispersed spherical particles were studied. A thin homogeneous elastic interphase with different shear and bulk moduli, located between the reinforced particle and the host matrix, was introduced to model the interfacial bonding state. The effects of such an interphase on the coherent plane waves were studied numerically. Numerical simulations were carried out for SiC-Al composites with four typical cases of interphase. It was found that the property of interphase has significant influences on the effective propagation constants of coherent waves and the dynamic effective elastic moduli of the composites. The influences on the coherent longitudinal wave and the coherent shear waves were different and dependent upon the frequency range. Moreover, several imperfect interface models, i.e., the spring model, mass model, and spring-mass model, were studied numerically and compared with the interphase model, It was found that the spring model is a more suitable model than the mass model for the light and weak interphase whereas the mass model is a more suitable model than the spring model for the heavy and strong interphase.

关键词： composites effective property coherent wave interface model interphase multiple scattering

Urbanization: positive and negative effects

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2019年第5期64卷 281-283页

作者： Chaolin gu School of Architecture Tsinghua University

Urbanization is a sign of modernization,and both developed and developing countries attach great importance to this *** is also a process in which the population continues to flow in urban areas,the non-agricultural industries(manufacturing and seivice industries)concentrate and develop,and the structure of human society gradually *** drives economic *** the urban form,and in fluences production technologies,citizen lifestyles,and societal ***,urbanization can have negative impacts on social equity,public health,and the natural *** the positive effects of urbanization while mitigating the negative effects is necessary for sustaining urban progress and improving human ***,the"urban disease"and regional inequalities caused by urbanization will become increasingly severe,especially in rapidly urbanizing countries.

关键词： Urbanization positive negative effects

Digitalized Accurate Modeling of SPCB with Multi-spiral Surface Based on CPC Algorithm

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2015年第5期28卷 1039-1047页

作者： HUANG Yanhua gu Lizhi College of Mechanical Engineering and Automation Huaqiao University

The main methods of the existing multi-spiral surface geometry modeling include spatial analytic geometry algorithms, graphical method, interpolation and approximation algorithms. However, there are some shortcomings in these modeling methods, such as large amount of calculation, complex process, visible errors, and so on. The above methods have, to some extent, restricted the design and manufacture of the premium and high-precision products with spiral surface considerably. This paper introduces the concepts of the spatially parallel coupling with multi-spiral surface and spatially parallel coupling body. The typical geometry and topological features of each spiral surface forming the multi-spiral surface body are determined, by using the extraction principle of datum point cluster, the algorithm of coupling point cluster by removing singular point, and the ＂spatially parallel coupling＂ principle based on the non-uniform B-spline for each spiral surface. The orientation and quantitative relationships of datum point cluster and coupling point cluster in Euclidean space are determined accurately and in digital description and expression, coupling coalescence of the surfaces with multi-coupling point clusters under the Pro/E environment. The digitally accurate modeling of spatially parallel coupling body with multi-spiral surface is realized. The smooth and fairing processing is done to the three-blade end-milling cutter＇s end section area by applying the principle of spatially parallel coupling with multi-spiral surface, and the alternative entity model is processed in the four axis machining center after the end mill is disposed. And the algorithm is verified and then applied effectively to the transition area among the multi-spiral surface. The proposed model and algorithms may be used in design and manufacture of the multi-spiral surface body products, as well as in solving essentially the problems of considerable modeling errors in computer graphics and engineeri

关键词： coupling point cluster algorithm topological features multi-spiral surface coupling spatially parallel coupling body datum point cluster

Low-Temperature Optical Spectra and Zero-Phonon Transitions of Color Centers in γ-Rayed Sodium Fluoride Crystals

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1993年第9期10卷 543-546页

作者： gu Hongen Department of Physics TUuijin UniversityTianjin 300072

A lot of narrow *** R_(2),R^(+),N_(1),N^(-) and some other un kowll centers have been observed in γ-raycd pure and doped sodium fuoride crystals in the temperature range of 9-77 *** proper laser irradiation was used for strengthening the zero-phonon lines and the relative explanation was *** spectral properties and thermosta-bilities of the lines were in vestigated systematically at difcrent temperatures.

关键词： Transition narrow explanation