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61.
国家(地区)间总产出波动存在相互影响是全球化时代的普遍现象,但缺少其相互影响强度的定量研究.基于冲击在非对称的区域间产业网络上的传播,分析了区域间总产出波动相互影响的机理,并依据区域间产品关联,构建了以区域为节点的度量区域间总产出波动相互影响的区域赋权影响网络.通过对网络度关联结构、基础关联结构、核关联结构及非对称结构四个维度的分析,定量描述了区域间总产出波动相互影响的强度.实例分析表明,该模型及相关度量维度能够量化不同区域间总产出波动的相互影响,定量描述某个国家(地区)在多区域经济大系统中的作用,在区域经济合作、贸易规则制定以及全球价值链构建等方面具有重要的理论和实际意义. 相似文献
62.
A newly proposed distributed dynamic state estimation algorithm based on the maximum a posteriori (MAP) technique is generalised and studied for power systems. The system model involves linear time-varying load dynamics and nonlinear measurements. The main contribution of this paper is to compare the performance and feasibility of this distributed algorithm with several existing distributed state estimation algorithms in the literature. Simulations are tested on the IEEE 39-bus and 118-bus systems under various operating conditions. The results show that this distributed algorithm performs better than distributed quasi-steady state estimation algorithms which do not use the load dynamic model. The results also show that the performance of this distributed method is very close to that by the centralized state estimation method. The merits of this algorithm over the centralized method lie in its low computational complexity and low communication load. Hence, the analysis supports the efficiency and benefits of the distributed algorithm in applications to large-scale power systems. 相似文献
63.
Product diffusion refers to the phenomenon that the later demand is dependent on the early sales. To investigate how a firm’s advance selling strategy is affected by the effect of product diffusion, we consider a monopolist seller who sells a fashionable product in a market that comprises of myopic and strategic consumers over two periods (i.e., the advance selling season and the regular selling season). For a linear product diffusion effect we find that, when the effect of product diffusion is positive, the seller may set an extremely high advance selling price to induce the strategic consumers to purchase in the regular selling season, which is counter-intuitive. Moreover, the optimal procurement quantity for the seller may increase in the negative effect of product diffusion and decrease in the amount of strategic consumers. When we extend our model to consider a concave quadratic product diffusion effect, however, the optimal procurement quantity is concave in the amount of strategic consumers. Numerical studies are further presented to discuss the managerial insights. 相似文献
64.
65.
NECESSARY AND SUFFICIENT CONDITION FOR GLOBAL CONTROLLABILITY OF A CLASS OF AFFINE NONLINEAR SYSTEMS
Yimin SUN Shengwei MEI Qiang LU 《系统科学与复杂性》2007,20(4):492-500
In this paper, we investigate the global controllability of a class of n-dimensional affine nonlinear systems with n- 1 controls and constant control matrix. A necessary and sufficient condition for its global controllability has been obtained by using the methods recently developed. Furthermore, we generalize the above result to a class of affine nonlinear systems with a block-triangular-like structure. Finally, we will give three examples to show the applications of our results. 相似文献
66.
《特种建筑材料》双语教学的探索与实践 总被引:1,自引:0,他引:1
就《特种建筑材料》采用双语教学的教材、课件、教学形式、作业、考试等问题进行了探讨,并对《特种建筑材料》开展双语教学一年多来的成效进行了分析,希望对其他课程的双语教学开设有一定借鉴作用。 相似文献
67.
We developed a parallel object-relational DBMS named PORLES. It uses BSP model as its parallel computing model, and monoid calculus as its basis of data model. In this paper, we introduce its data model, parallel query optimization, transaction processing system and parallel access method in detail. 相似文献
68.
69.
2011年6月22日-9月1日,香山科学会议先后召开了主题为:“音乐声学”、“老龄健康影响因素与保障机制的综合交叉研究”、“空间引力波探测”、“物质科学综合极端条件”的第401-404次学术讨论会。 相似文献
70.
Rasmussen SG DeVree BT Zou Y Kruse AC Chung KY Kobilka TS Thian FS Chae PS Pardon E Calinski D Mathiesen JM Shah ST Lyons JA Caffrey M Gellman SH Steyaert J Skiniotis G Weis WI Sunahara RK Kobilka BK 《Nature》2011,477(7366):549-555
G protein-coupled receptors (GPCRs) are responsible for the majority of cellular responses to hormones and neurotransmitters as well as the senses of sight, olfaction and taste. The paradigm of GPCR signalling is the activation of a heterotrimeric GTP binding protein (G protein) by an agonist-occupied receptor. The β(2) adrenergic receptor (β(2)AR) activation of Gs, the stimulatory G protein for adenylyl cyclase, has long been a model system for GPCR signalling. Here we present the crystal structure of the active state ternary complex composed of agonist-occupied monomeric β(2)AR and nucleotide-free Gs heterotrimer. The principal interactions between the β(2)AR and Gs involve the amino- and carboxy-terminal α-helices of Gs, with conformational changes propagating to the nucleotide-binding pocket. The largest conformational changes in the β(2)AR include a 14 ? outward movement at the cytoplasmic end of transmembrane segment 6 (TM6) and an α-helical extension of the cytoplasmic end of TM5. The most surprising observation is a major displacement of the α-helical domain of Gαs relative to the Ras-like GTPase domain. This crystal structure represents the first high-resolution view of transmembrane signalling by a GPCR. 相似文献