检索结果-南通市图书馆

Frontiers of Environmental Science & Engineering 2017年第5期11卷 125-134页

作者： Jian li zhen Wang Bao Jiang College of Economics Ocean University of China Qingdao 266100 China Marine Development Studies Institute Ocean University of China Qingdao 266100 China

In addition to maximizing economic benefits, reverse supply chains should further seek to maximize social benefits by increasing the quantity of waste electrical and electronic equipment （WEEE）. The paper investigates cooperative models with different parties in a three-echelon reverse supply chain for WEEE consisting of a single collector, a single remanufacturer, and two retailers based on complete information. In acldition, the optimal decisions of four cooperative models and the effect of the market demand of remanufactured WEEE products and the market share of two retailers on the optimal decisions are discussed. The results indicate that optimal total channel profit and recycle quantity in a reverse supply chain are maximized in a centralized model. The optimal total channel profit and recycle quantity increase with an increase in the market demand of remanufactured WEEE products. The three-echelon reverse supply chain consisting of duopolistic retailers maximizes total channel profit and recycle quantity in a reverse supply chain fbr WEEE.

关键词： Waste electrical and electronic equipment(WEEE)Reverse supply chains Recycle quantitySocial benefit Cooperative models Duopolistic retailers

Experiment of heat transfer in oscillating turbulent flow in a pipe with constant heat flux

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

航空动力学报 2013年第9期28卷 1949-1955页

作者： li Ming-zhen DONG Jin-zhong School of Energy and Power Engineering Beijing University of Aeronautics and Astronautics

Heat transfer characteristics of oscillating turbulent air flow in a pipe heated with constant heat flux were experimentally *** experiments were performed over a range of 245.7 to 902 of the kinetic Reynolds number and 25 to 175 of the dimensionless oscillation *** effects of these two dimensionless parameters were *** results show that the cycle-averaged local Nusselt number increases with both the kinetic Reynolds number and the dimensionless oscillation *** space-cycle averaged Nusselt number also effectively increases with the kinetic Reynolds number and the dimensionless oscillation *** on the experimental data,a correlation equation of the space-cycle averaged Nusselt number for air in terms of these two dimensionless parameters has been obtained.

关键词： oscillating turbulent flow heat transfer kinetic Reynolds number Nusselt number constant heat flux

Identifi cation of a novel male sterile wheat mutant dms conferring dwarf status and multi-pistils

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2015年第9期14卷 1706-1714页

作者： DUAN zong-biao SHEN Chun-cai li Qiao-yun Lü Gui-zhen NI Yong-jing YU Dong-yan NIU Ji-shan National Centre of Engineering and Technological Research for Wheat Henan Agricultural University Shangqiu Academy of Agricultural and Forestry Sciences

Plant height and fertility are two important traits of wheat (Triticum aestivum L.), whose mutants are ideal materials for studies on molecular mechanisms of stem and lforal organ development. In this study, we identiifed a dwarf, multi-pistil and male sterile (dms hereafter) wheat mutant from Zhoumai 18. Simple sequence repeat (SSR) marker assay with 181 primer pairs showed that only one locus of GWM148-2B was divergent between Zhoumai 18 and dms. There were three typical phenotypes in the progeny of dms, tal (T;ca. 0.8 m), semi-dwarf (M;ca. 0.6 m) and dwarf (D;under 0.3 m) plants. Morphological investigation indicated that the internode length of M was shortened by about 20–50 mm each;the internode number of D was 2 less than that of T and Zhoumai 18, and its internode length was shorter also. The pol en vigor and hybridization test demonstrated that dms mutant was male sterility. Segregated phenotypes in progeny of M suggested that the multi-pistils and sterility were control ed by one recessive gene locus which was designated as dms temporarily, and the plant height was control ed by a semi-dominant gene locus Dms. Therefore, progeny individuals of the dms had three genotypes, DmsDms for tal plants, Dmsdms for semi-dwarf plants and dmsdms for dwarf plants. The mutant progenies were individual y selected and propagated for more than 6 generations, thus a set of near isogenic lines of T, M and D for dms were developed. This study provides a set germplasms for studies on molecular mechanisms of wheat stem and spike development.

关键词： wheat mutant dwarf multi-pistil male sterility

Synthesis Mechanism and Material Characterization of C4AF Obtained by the Self-propagating Combustion Reaction Method

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2018年第5期33卷 1099-1107页

作者： HE zhen li Yang Shaanxi Key Laboratory of Safety and Durability of Concrete Structure Xoing UniversityXi＇an 710123China State Key Laboratory of Water Resources ＆ Hydropower Engineering Science Wuhan UniversityWuhan 430072China

To investigate the influence of preparation process on the properties of synthesized C4AF,the powder was prepared via the self-propagating combustion reaction（SPCR）method using urea as fuel and metal nitrates as cation *** mechanism of the SPCR method,calculation and adjusting principles of urea dosage were detailedly *** characterization of synthesized C4AF was performed with the aid of X-ray diffractometry,Fourier transform infrared spectrometry,scanning electron microscopy,energydispersive X-ray spectroscopy,^27Al nuclear magnetic resonance and isothermal microcalorimetric *** content of transition phase of calcium carbonate in synthesized C4AF was determined by quantitative analysis of X-ray *** was found that there was no difference in the hydration behavior of C4AF synthesized by the SPCR method and the traditional solid-state reaction（SSR）method.C3AH6 and amorphous iron（III）hydroxide（Fe（OH）3）would be formed during the hydration of C4AF while CH *** size of synthesized C4AF was 16.1 A and the apparent activation energy was 36.2 kJ/*** condition of Al in C4AF can be detected by ^27Al NMR technique,but the peaks were broadened and the intensities were relatively low,supporting the use of ^27Al NMR for the quantitative analysis of C3A in Portland cements.

关键词： C4AF self-propagating SPCR urea ^27Al NMR apparent activation energy

Optimization of thermal processing parameters of Ti555211 alloy using processing maps based on Murty criterion

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2016年第2期35卷 154-161页

作者： zhen An Jin-Shan li Yong Feng State Key Laboratory of Solidification Processing Northwestern Polytechnical University

Isothermal compression testing of Ti555211 titanium alloys was carried out at deformation temperatures from 750 to 950 °C in 50 °C intervals with a strain rate of0.001-1.000 s^（-1）. The high-temperature deformation behavior of the Ti555211 alloy was characterized by analysis of stress-strain behavior, kinetics and processing maps. A constitutive equation was formulated to describe the flow stress as a function of deformation temperature and strain rate, and the calculated apparent activation energies are found to be 454.50 and 207.52 k J mol^（-1）in the a b-phase and b-phase regions, respectively. A processing map based on the Murty instability criterion was developed at a strain of 0.7. The maps exhibit two domains of peak efficiency from 750 to 950 °C. A ＊60 % peak efficiency occurs at 800-850 °C/0.001-0.010 s^（-1）. The other peak efficiency of ＊60 % occurs at C950 °C/0.001-0.010 s^（-1）, which can be considered to be the optimum condition for high-temperature working of this ***, at strain rates of higher than 1.000 s^（-1）and deformation temperatures of 750 and 950 °C, clear process flow lines and bands of flow localization occur in the hightemperature deformation process, which should be avoided in Ti555211 alloy hot processing. The mechanism in stability domain and instability domain was also discussed.

关键词： Ti555211 titanium alloy High temperature Deformation behavior Processing maps

Mobility Analysis of Altmann Overconstrained linkages by Modified Grübler-Kutzbach Criterion

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2011年第4期24卷 638-646页

作者： liU Jingfang li Yanwen HUANG zhen College of Mechanical Engineering andApplied Electronics Technology Beijing University of Technology Beijing 100124 China Robotics Research Center Yanshan University Qinhuangdao 066004 China

Developing a general mobility method/formula is a hot topic lasting for more than 150 years in kinematics. It is necessary to apply any mobility method to puzzling overconstrained mechanisms for verification of its generality. Altmann linkages are such recognized puzzling mechanisms that their mobility analysis is of important significance. A necessary condition for judging a general mobility method is that the method can be fit for Altmann linkages. Firstly, this study classes Altmann linkages into 17 types in terms of the numbers and types of kinematic pairs, and then Altmann overconstrained linkages are further classified into 4 types. Secondly, the mobility of Altmann overconstrained linkages is systematically analyzed by the Modified Grübler-Kutzbach criterion based on screw theory, where passive freedoms are defined as limb passive freedoms and mechanism passive freedoms. In addition, the full-cycle mobility is judged, which overcomes the shortcoming of instantaneous property of screw theory. It is shown that Modified Grübler-Kutzbach criterion not only obtains the correct numerical mobility, but also gives the mobility character by resolving reciprocal screws for the constraint system. This study lays the foundation of verification for the generality of Modified Grübler-Kutzbach criterion. Besides, Altmann overconstrained linkages almost comprise all kinds of modern parallel mechanisms and some classical mechanisms, which provides an important reference for mechanism mobility calculation.

关键词： mobility analysis overconstrained linkage screw theory

Real-world traffic analysis and joint caching and scheduling for in-RAN caching networks

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2017年第6期60卷 176-190页

作者： Zejue WANG Hongjia li zhen XU State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of Sciences

This paper analyzes the traffic of a current LTE network in China and investigates the joint optimization of content object caching and scheduling for in-radio access network(RAN) caches. Cooperative caching has been well recognized as a way of unleashing the ultimate potential of in-RAN caches, yet its feasibility is still unexplored. Moreover, content object caching and scheduling are two key issues for cache deployment,which are usually jointly considered and resolved. However, they are triggered by different events with different time granularities. Therefore, on the basis of the real-world dataset, the feasibility of in-RAN cooperative caching is proved from aspects of network topology, traffic load difference among small base stations(SBSs)and correlation analysis of content objects requested at different SBSs. Then, it is verified that different time scales should be considered in making content object caching and scheduling decisions. To exploit in-RAN cooperative caching while meeting the time scale requirement in making caching and scheduling decisions, an optimization problem is constructed considering practical transmission constraints in wireless and backhaul. It is proved to be a quadratic assignment problem, and then, a joint caching, and wireless and backhaul scheduling algorithm is proposed based on Lagrangian relaxation and decomposition, and hastening branch and *** performance of the proposed algorithm is evaluated based on the real-world dataset. Results depict the relationship among the cache capacity, the number of SBSs, the connection probability of SBSs and the objective performance, and show that the proposed algorithm can achieve better performance, compared with the existing algorithms.

关键词： 5G mobile edge caching mobile traffic analysis optimization cooperative caching

PRICING AND HEDGING PROBLEM OF FOREIGN CURRENCY OPTION WITH HIGHER BORROWING RATE

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2013年第3期26卷 407-418页

作者： CHEN li HUANG zongyuan WU zhen Department of Mathematics China University of Mining Technology School of Mathematics Shandong University

The pricing and hedging problem of foreign currency option with higher borrowing rate is *** method to obtain the price and hedging portfolio of currency option is based on backward stochastic differential equations(BSDE for short) theory and Malliavin calculus *** sensitivity of the model parameters is also considered and some numerical simulations are given to illustrate our conclusion.

关键词： Backward stochastic differential equation Malliavin calculus portfolio strategy pricing.

An aero-engine life-cycle maintenance policy optimization algorithm: Reinforcement learning approach

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2019年第9期32卷 2133-2150页

作者： zhen li Shisheng ZHONG lin liN School of Mechatronics Engineering Harbin Institute of Technology

An aero-engine maintenance policy plays a crucial role in reasonably reducing maintenance cost. An aero-engine is a type of complex equipment with long service-life. In engineering,a hybrid maintenance strategy is adopted to improve the aero-engine operational reliability. Thus,the long service-life and the hybrid maintenance strategy should be considered synchronously in aero-engine maintenance policy optimization. This paper proposes an aero-engine life-cycle maintenance policy optimization algorithm that synchronously considers the long service-life and the hybrid maintenance strategy. The reinforcement learning approach was adopted to illustrate the optimization framework, in which maintenance policy optimization was formulated as a Markov decision process. In the reinforcement learning framework, the Gauss–Seidel value iteration algorithm was adopted to optimize the maintenance policy. Compared with traditional aero-engine maintenance policy optimization methods, the long service-life and the hybrid maintenance strategy could be addressed synchronously by the proposed algorithm. Two numerical experiments and algorithm analyses were performed to illustrate the optimization algorithm in detail.

关键词： Aero-engine Hybrid strategy Maintenance policy Optimization algorithm Reinforcement learning

THE OPTIMAL CONVERGENCE ORDER OF THE DISCONTINUOUS FINITE ELEMENT METHODS FOR FIRST ORDER HYPERBOliC SYSTEMS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2008年第5期26卷 689-701页

作者： Tie Zhang Datao Shi zhen li Department of Mathematics and School of Information Science and Engineering Northeastern University Shenyang 110004 China

In this paper, a discontinuous finite element method for the positive and symmetric, first-order hyperbolic systems （steady and nonsteady state） is constructed and analyzed by using linear triangle elements, and the O（h^2）-order optimal error estimates are derived under the assumption of strongly regular triangulation and the Ha-regularity for the exact solutions. The convergence analysis is based on some superclose estimates of the interpolation approximation. Finally, we discuss the Maxwell equations in a two-dimensional domain, and numerical experiments are given to validate the theoretical results.

关键词： First order hyperbolic systems Discontinuous finite element method Convergence order estimate.