国内外学前儿童计算思维研究述评

人工智能时代,计算思维已成为21世纪个体的必备素养。近年来,人们开始逐渐意识到从儿童早期培养计算思维的重要性,从小开始培养儿童的计算思维已成为世界各国的共识。然而,当前尚未对学前儿童计算思维的研究进行全面系统地梳理。因此,本研究结合文献计量法与内容分析法,对来自国内外核心数据库中的30篇实证研究进行了系统梳理,以此全面地了解国内外学前儿童计算思维培养的研究现状与发展趋势。与此同时,立足现状提出了对策与展望。     

On the difficulty of making social choices

The difficulty of making social choices seems to take on two forms: one that is related to both preferences and the method used in aggregating them and one which is related to the preferences only. In the former type the difficulty has to do with the discrepancies of outcomes resulting from various preference aggregation methods and the computation of winners in elections. Some approaches and results which take their motivation from the computability theory are discussed. The latter institution-free type of difficulty pertains to solution theory of the voting games. We discuss the relationships between various solution concepts, e.g. uncovered set, Banks set, Copeland winners. Finally rough sets are utilized in an effort to measure the difficulty of making social choices.     

The Evolution of Knowledge and the Dynamics of an Industry Network

The paper moves a step forward in the direction of establishing a connection between the structure and evolution of knowledge bases and the structure and evolution of organizational forms in innovative activities in a science-intensive industry. The paper has an explicit focus on the dynamics of the network of collaborative agreements in R&D in the pharma/biotech industry after the “molecular biology revolution”. Using a comprehensive dataset, built by the authors integrating several sources in the industry, the dynamics of the network over time is extensively analyzed. With regards to network structure, it is found that, while the size of the network increases over time due to net flows of entry, its topological properties remain relatively unchanged. The evolution of the network has occurred without relevant deformations in the core-periphery profile. With regards to age-dependent propensity to collaborate, the paper finds that the extent of inter-generational collaboration is much more significant than intra-generational collaboration. In addition, the propensity of firms of a given generation to enter into collaboration with firms of a different generation increases with the distance between the two, while the total number of intra-generational collaborations decreases over time and, moreover, tends to decrease for most recent generations. In the paper a unitary and coherent explanation of the evidence is developed, coming to reveal the existence of a striking isomorphism between structural properties of the dynamics of knowledge and of the evolution of network structure. This revised version was published online in July 2006 with corrections to the Cover Date.     

Adaptive Build-up and Breakdown of Trust: An Agent Based Computational Approach

This article employs Agent-Based Computational Economics (ACE) to investigate whether, and under what conditions, trust is viable in markets. The emergence and breakdown of trust is modeled in a context of multiple buyers and suppliers. Agents develop trust in a partner as a function of observed loyalty. They select partners on the basis of their trust in the partner and potential profit, with adaptive weights. On the basis of realized profits, they adapt the weight they attach to trust relative to profitability, and their own trustworthiness, modeled as a threshold of defection. Trust and loyalty turn out to be viable under fairly general conditions.     

Minimal Tetrahedralizations of a Class of Polyhedra

Given a simple polyhedron P in the three dimensional Euclidean space, different tetrahedralizations of P may contain different numbers of tetrahedra. The minimal tetrahedralization is a tetrahedralization with the minimum number of tetrahedra. In this paper, we present some properties of the graph of polyhedra. Then we identify a class of polyhedra and show that this kind of polyhedra can be minimally tetrahedralized in O(n ²) time.     

一种新的高分辨定位去噪方法

高分辨定位技术在近几年得到人们的广泛注意,在这方面的研究工作相当活跃。本文提出一种新的多目标阵列接收信号协方差矩阵的去噪方法,并对结果进行了计算机模拟。     

社会网络对民间金融风险的作用——基于社会网络结构的理论与实证分析

社会网络对民间金融风险的影响已被广泛认可,但是,究竟什么样的网络结构有抑制风险的作用,什么样的网络结构有扩增风险的作用？以资金互助会为例,将互助会涉及的社会网络按结构特征分为单个会的会内网络和多个会的会间网络,研究可知：（1）越紧密的会内网络结构以及越大的网络规模越有利于民间金融风险的控制。（2）跨会网络具有抑制和扩增风险两种作用,它是协同监督和惩罚机制生效的基础,因而对风险具有控制作用,但这种作用只在中介成员为会首时才显著;同时,它也构成了风险传播的通道,导致资金被分散到多个会中,因而提升了系统性风险。     

论鲜卑段部的源流和兴衰

段部出于东部鲜卑,其远祖为先秦时期的屠何,早期活动于徒河地区,北朝时段部与慕容部、乌桓又同称为徒何。段部的兴衰与晋末十六国时期的政局变化有着密切关系,段部与司马越、王浚结援,在司马越当政之时而走向强盛,随着司马越集团的败亡及临敌石赵、慕容燕的崛起而逐渐走向衰亡。同时,段部的兴衰也对晋末十六国政局产生了很大影响。     

城镇化背景下大遗址管理体制的突破与困境

对大遗址管理而言,我国正稳步推进的城镇化既是机遇,也是挑战。为回应这些机遇或挑战,“十一五”前后我国从中央到地方采取了一系列措施,以寻求大遗址管理体制中管理架构和机构的部分突破。这些突破对大遗址保护已经或正在产生积极影响,但也面临着政策不具普适性、无法根除原管理框架痼疾等困境。促成大遗址保护需求与规划的衔接、引入社会力量参与大遗址管理,是突破困境的重要手段。     

民国商业出版与左翼文学潮流的兴起——兼以1930年代良友图书印刷公司的转变为例

将1930年代左翼文学潮流的兴起置于＂民国＂这一社会历史的政治经济研究框架中,可以看到其与民国时期商业出版的经济环境有着十分密切的关系。从此视角出发并结合相关史料,兼以良友图书印刷公司的转变为实例,探寻在与出版业广泛互动的条件下,一度风行文坛进而成为声势浩大＂主潮＂的左翼文学潮流的生成机制。