S195连杆螺钉的冷挤压工艺研究

在分析了S195连杆螺钉传统的热模锻存在问题的基础上,指出该螺钉冷挤压加工的必要性。对该螺钉的冷挤压工艺进行了深入地研究,从而提出了切实可行的冷挤压工艺。     

多目标、多水源和多用户水资源系统管理的专家系统决策模型

几乎所有的水资源系统都是以多目标、多水源和多用户等为特征，因此其开发与管理过程中的各种决策也都必须坚持这些原则。本文利用现代专家系统技术建立了一种水资源系统管理的专家系统决策模型。该水资源系统包含一个地面水库供水系统、两个城镇市政供水系统、３个农区灌溉系统以及一个沼泽生态系统。它最早源于英国７０年代初所提出的灌溉系统对策仿真的设想，后经国外其他学者的不断完善，最后形成一种接近于现实的简单而综合的水资源系统管理原型，并以对策仿真的形式建立了其ＬＯＴＵＳ模拟模型。该对策仿真模拟模型中的对策者是地面水源管理者（ＷＡＭ）、市政供水管理者（ＰＷＳＭ）以及三组不同农户（ＦＡＲＭＥＲＳ）。为了使该系统更趋完善且更符合我国国情，本文又另外引入了一个称之为系统总管的对策者（ＭＡＮＡＧＥＲ）。他主要负责该系统的全面运行，解决系统中各对策者之间的矛盾冲突，监控全系统的环境质量，尽可能使整个系统获得最佳的社会、经济与环境效益。这种对策仿真模拟模型的主要目的是培养参加对策仿真的各位对策者，或者说水资源系统中的有关各方，即不同角色，更加熟悉一般水资源系统运行与管理过程中的各个方面。本文利用应用于微机的ＶＰ－专家系统外壳建立了这种对策仿     

高校艺术教育在素质教育中的积极作用

各国的教学实践已充分证明了艺术教育在提高学生人文素质，促进社会全面发展等方面发挥着积极而重要的作用。本文从高校艺术教育中遭遇尴尬现象的原因入手，浅略地分析了艺术教育对提高学生素质的重要作用及其对素质教育正面促进功能，并认为在加强素质教育的过程中我国高校艺术教育的建设任重道远。     

Sonochemical degradation of organophosphorus pesticide in dilute aqueous solutions

Ultrasonic irradiation was found to accelerate the rate of hydrolysis of omethoate in aqueous solution over the pH range of 2—12. Process parameters studied include pH, steady-state temperature, concentration, and the type of gases, Greater than 96% hydrolysis was observed in 30 minutes through this process and the rate of destruction increased with the help of more soluble and low thermal inert gas. So with Krypton, omethoate was found to undergo rapid destruction as compared with Argon. In the presence of ultrasound, the observed first-order rate of hydrolysis of omethoate is found to be independent of pH. The formation of transient supercritical water(SCW) appears to be an important factor in the acceleration of chemical reactions in the presence of ultrasound. A detaiied chemical reaction mechanism for omethoatedestruction in water was formulated. Experimental results and theoretical kinetic mechanism demonstrated that the most of the omethoate undergo destruction inside the cavitating holes. A very less effect of temperature on the degradation of omethoate within a temperature range of 20——70℃ proves that a small quantity of omethoate undergoes secondary destruction in the bulk liquid.     

论政府在环境保护中的作用

在理想市场状态下,个体利益最大化能够导致资源的有效配置,但当存在能影响价格的市场势力、外部性、公共物品及不完全信息时,就会出现资源配置的扭曲,即市场失灵.市场失灵为政府干预提供了机会和理由.环境保护政府干预的必要性,政府在环境保护中的作用,但政府干预也并不总是有效的,指出了政府履行环境保护服务职能存在的问题,分析环境保护中政府"失灵"的原因:决策判断失误、利益集团影响、决策信息不全、体制不健全等,提出了充分发挥政府在环境保护中作用的对策措施.     

乘子法在求解拥挤交通问题中的应用

笔者讨论了具有能力约束 ,带拥挤排队现象的城市交通配流问题 ,包括静态的UE配流模型和动态的用户最优配流模型 ,并建立了相应的数学规划模型来进行描述 ,说明了模型的解与用户平衡条件之间的等价性 ,在给出了乘子法的理论依据的基础上 ,分别设计了基于乘子法的求解带有路段能力限制的静态UE和动态用户最优模型的算法 ,并给出了算法的具体步骤。     

浅谈我国电力工业在节能减排中的作用

本文阐述了电力工业在节能减排中存在的问题,提出了电力工业解决节能减排问题的建议和意见,其中加强电力行业有关法律法规政策的建设是节能减排的保障,自动化技术的提高及广泛应用是实现节能减排的关键,如能按此实施,我国的节能减排工作一定前景美好,为世界环保作出应有的贡献。     

Global trends in research output by zoos and aquariums

Zoos and aquaria, often regarded as preservation-cum-entertainment enterprises, are also actors in the effort to curb the biodiversity crisis: raising awareness, supporting conservation, and conducting research. We assessed trends in zoo and aquaria research topics and study organisms over time worldwide. For the zoos and aquaria registered in the Species360's Zoological Information Management System and the World Association of Zoos and Aquariums, we compiled metadata on their research published in the peer-reviewed literature indexed in Scopus and carried out a keyword frequency analysis. The production of scientific papers by zoos increased at a much faster rate than the average accrual of scientific papers in the literature. Evolution of research themes ran parallel to that of biological sciences (e.g., development of molecular genetics or increased awareness about conservation). The focus of 48.5% of zoo-led research was on vertebrates, of which mammal research was 33.7%. Whether zoos are effectively contributing to conservation may still be debatable, but our results highlight their institutional efforts to increase knowledge about the species in their care.     

Gender-role alternation in the simultaneously hermaphroditic freshwater snail <Emphasis Type="Italic">Physa acuta</Emphasis>: not with the same partner

In simultaneous hermaphrodites, gender conflicts that arise from two potential mates sharing the same gender preference may be solved through conditional reciprocity (or gamete trading). Conditional reciprocity had initially been considered widespread, but recent studies suggest that its real occurrence may have been overestimated, possibly because most mating observations have been performed on isolated pairs of individuals. Some resulting patterns (e.g., non-random alternation of sexual roles) were indeed compatible with conditional reciprocity but could also have stemmed from the two partners independently executing their own mating strategy and being experimentally enforced to do so with the same partner. Non-random alternation of gender roles was recently documented in the simultaneously hermaphroditic freshwater snail Physa acuta. To distinguish between conditional and unconditional gender alternations, we observed copulations of individually marked snails reared at three contrasted densities. We showed that density affected the overall frequency of copulations during the first 2 days of the experiment with high-density boxes showing more copulations than low density boxes, but it did not affect gender alternation patterns. A change in gender role was observed more often than expected by chance over two successive copulations by the same individual, confirming previous studies. However, gender switches did not preferentially occur with the same partner. We conclude that gender alternation is not due to conditional reciprocity in P. acuta. It may rather stem from each individual having a preference for gender alternation. We finally discuss the mechanisms and the potential extent of this unconditional reciprocity.