春季石家庄市水体浮游植物群落结构调查与分析

为探索春季石家庄市水体浮游植物群落组成与结构特点,及其主要环境影响因素,对水体中浮游植物的种类组成、细胞密度、环境因子等指标进行了调查,分析了其物种优势度、多样性指数,并对各水体的浮游植物组成与环境因子进行了聚类分析和相关性分析。结果发现:在春季的石家庄市水体中,共检出浮游植物7门47属76种,以绿藻门种类最多,约占总数的39.47%,其次为硅藻和蓝藻,裸藻、金藻、黄藻和甲藻种类很少且仅在个别采样点位出现。水体中硅藻细胞密度最高,平均为1.0×10~7 cells/L,占丰度组成的61.84%,其次为绿藻和蓝藻。值得注意的是,岗南水库是所有水体中仅有的金藻丰富型水体,它的金藻细胞密度高达4.5×10~6 cells/L。物种优势度分析和多样性指数分析显示,石家庄市水体中以中度富营养型指示藻类为优势类群,基本处于中度污染水平;水体聚类分析表明,石家庄市水体的浮游植物组成受整体水环境因素影响不明显;而单环境因子数据及其与浮游植物的相关性分析表明,石家庄市水质酸化严重(pH值低于6.0),除科大牧星湖和岗南水库外,多数水体处于劣V类水平,主要超标物为pH值、总磷、总氮和COD,而这可能是导致蓝藻、绿藻等耐污性种类大量繁殖的主要因素。因此,对石家庄市水体中浮游植物群落组成与结构变化的生物学监测,是进行石家庄市地表水水质监测及生态保护的重要途径。     

The core‐peripheral structure of international knowledge flows: evidence from patent citation data

The importance of knowledge diffusion and external knowledge is generally acknowledged for their vital role to innovation. The purpose of this study is to investigate the international knowledge diffusion structure and its evolution using patent citation networks for three periods. The analyses are carried out from overall, active cluster as well as individual connection perspectives with the help of measures from social network analysis. Results show an obvious core‐peripheral structure of international knowledge diffusion. Most of the flows happen within core group. Knowledge flows between core and peripheral numbers also widely exist but not strong, while the flows among peripheral numbers are both sparse and weak. Significant improvements widely exist among Asian countries and regions according to their knowledge absorption and influence capacities, and Chinese Taiwan and South Korea are the most outstanding new stars among them with worthwhile experiences for other catch‐ups. It also suggests that BRICS and South–South knowledge linkages play an increased role in developing and emerging economy innovation systems as they gain momentum.     

基于MA2IDDPG算法的异构多无人机协同突防方法

为了形成智能化异构多无人机协同突防策略,提出了基于多智能体异步模仿深度确定性策略梯度算法的异构多无人机协同突防方法。首先,基于典型DDPG方法,采用异步并行框架进行改进,提高经验的收集效率。其次,分别构建基于专家经验知识的牵引性奖赏函数和基于任务结果的描述性奖赏函数。再次,通过分阶段训练后,使得深度神经网络产生的协同突防策略能够快速达到专家经验知识水平后,进一步提高对抗水平。最后,在仿真实验中,构建了异构多无人机协同突防环境,对改进方法和典型DDPG方法的对抗效果进行了对比。实验结果表明,MA2IDDPG方法能够有效产生多无人机协同突防策略,并且在训练阶段表现更为稳定且对抗效果更优。所设计的创新性MA2IDDPG方法框架可有效应用于无人机群控制领域,特别是对异构无人机群的智能控制方法研究具有重要参考意义。     

Evaluation method of benefits and efficiency of grid investment in China: A case study

The existing evaluation system for power grid investment in China has not combined measures of the investment benefits and investment efficiency very well and it lacks practical reference value. This article proposes an improved evaluation index system of the benefits and efficiency of power grid investment projects. The system divides the evaluation method into indexes. This includes the basic indexes, modification indexes, and appraisal indexes that evaluate the economic and environmental benefits of the investment projects comprehensively. It considers the overall efficiency in terms of the economy, technology, and society. It combines an absolute efficiency evaluation model with a data envelope analysis relative efficiency evaluation model. Finally, the benefits and efficiency of investment of an actual power grid project are evaluated through a case study. The results show the practical value of the proposed efficiency evaluation method for evaluating investment projects in a power grid.     

伊拉克国际石油合作的机遇和风险

伊拉克探明原油储量居世界第三位,石油资源勘探开发程度相对较低,探明油气主要富集在中南部地区、西部沙漠地区和北部库尔德斯坦扎格罗斯地区.由于连年战乱,伊拉克石油工业损失严重.目前,伊拉克政府谋求重建石油工业,通过重要油田公开招标和非公开招标签约等方式,积极推进石油工业的国际合作,寻求国际资本投入,这将使外国企业在伊的石油合作机会增多.伊拉克新的石油法草案和招标合同模式已显现未来伊拉克国际石油合作的雏形.尽管面临安全风险、法律风险和国际竞争风险,对中国企业而言,现在就积极参与伊拉克石油国际合作,将有利于把握伊拉克石油动向和机遇,为以后扩大合作打下良好基础.     

公允价值课题中期汇报会召开

中国资产评估协会承担的财政部《公允价值计量——评估方法与实践》课题中期成果汇报会于2010年1月28日在京召开。会计司司长刘玉廷,课题组组长、中国资产评估协会秘书长刘萍及课题组主要成员参加了汇报会。会议由课题组副组长、中国资产评估协会副秘书长岳公侠主持。     

社区银行与关系型贷款:优势及成因分析

社区银行的比较优势突出地反映在其从事关系型贷款的能力上,此种贷款则以软信息的生产与运用为基本构成要素。与其自身在组织结构、所有权结构等方面所呈现的特点相关联,社区银行在软信息的收集、传递及使用上有着独特的优势,而此类银行在关系型贷款上之优势也正源于此。在我国,培育和发展社区银行,对于增进信息不透明的小型借款人的贷款可得性将具有现实意义。     

论内幕信息的界定

《最高人民法院、最高人民检察院关于执行<中华人民共和国刑法>确定罪名的补充规定(四)》将《刑法》第180条第4款规定为利用未公开信息交易罪。但该款规定的犯罪对象其他未公开的信息属于我国《证券法》规定的内幕信息的一种,即对该公司证券的市场价格有重大影响的尚未公开的信息。这种信息在其他国家与地区也是作为内幕信息认定的。对于违反我国《刑法》第180条第4款规定的行为,我们可以按照内幕交易罪进行处理。     

How asymmetric is U.S. stock market volatility?

This paper explores differences in the impact of equally large positive and negative surprise return shocks in the aggregate U.S. stock market on: (1) the volatility predictions of asymmetric time-series models, (2) implied volatility, and (3) realized volatility. Following large negative surprise return shocks, both asymmetric time-series models (such as the EGARCH and GJR models) and implied volatility predict an increase in volatility and, consistent with this, ex post realized volatility normally rises as predicted. Following large positive return shocks, asymmetric time-series models predict an increase in volatility (albeit a much smaller increase than following a negative shock of the same magnitude), but both implied and realized volatilities generally fall sharply. While asymmetric time-series models predict a decline in volatility following near-zero returns, both implied and realized volatility are normally little changed from levels observed prior to the stable market. The reasons for the differences are explored.