On the ontological expressiveness of information systems analysis and design grammars

Abstract. Information systems analysis and design (ISAD) methodologies provide facilities for describing existing or conceived real-world systems. These facilities are ontologically expressive if they are capable of describing all real-world phenomena completely and clearly. In this paper we formally examine the notion of the ontological expressiveness of a grammar and discuss some of its implications for the design and use of ISAD methodologies. We identify some generic ways in which ontological expressiveness may be undermined in a grammar and some potential consequences of these violations. We also examine ontological expressiveness within the context of some other desirable features that might be considered in the design of ISAD methodologies.     

伺服元件的生产应用及发展趋势

本文概括地介绍了我国自70年代以来伺服元件的生产发展状况、元件的性能特点和应用情况，并分析了今后发展的趋势。     

定向能武器技术发展的回顾与展望

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汽车自动传动液的研制

介绍了自动传统液的分类规格、自动传动液的特性和相关的评定方法；研制了无锌和低锌配方的两种产品，经评定试验和实机使用，符合ＤｅｘｒｏｎⅡＤ、Ｍｅｒｃｏｎ和ＡｌｌｉｓｏｎＣ－４的规格要求，达到了国外同类产品的质量水平。     

Can Fusion and Fission Breeding Help Civilization Survive?

As apparent from the title, this author feels that civilization faces a real threat, one which will become obvious and serious within the lifetimes of many readers of this article. This threat is not global warming, but lack of affordable energy. We take for granted turning on a light, or adjusting our thermostats in winter or summer, or filling our cars gas tank; and lose sight of the fact that there are huge and complicated industrial systems which make this possible. But as we run out of petroleum and natural gas, and worry about the environmental and climatic effects of burning coal on the required scale, how can this continue? This paper makes the case that breeding nuclear fuel, by both fusion and fission, is the only way our civilization as we know it, can continue beyond the next half century or so.     

通过室内实验及同位素测井技术评价高分子聚合物驱油效果

2500万超高分聚合物室内驱油实验研究了聚合物分子量、浓度、粘度、聚用量、段塞组合等各项性能指标对驱油效果的影响。本文根据室内实验结果,在北一区断西注聚后期开展矿场试验,取得了较好的开发效果。试验前后对比,注入粘度明显增大,月含水上升速度得到有效控制,吸入剖面有了新的动用,有63.1%的油井出现了明显的二次受效特征,取得了显著的经济效益。同时对驱油效果进行系统分析。驱油效果表明:应用2500万超高分聚合物是进一步提高聚驱采收率的有效途径。     

大井眼卡簧式铅封防砂封隔器的研制

为保证大井眼防砂井正常生产,研制了卡簧式铅封防砂封隔器。该封隔器主要由坐封机构、丢手装置、复合铅封组件及导向系统组成。卡簧式坐封机构的设计增大了坐封锁紧力,同时保证坐封安全可靠;滑块式丢手装置有效避免了刚体伤害;另外复合铅封组件采用内带刚性结构的高密度柔性石墨结构,耐温达350℃,适应稠油热采要求。室内试验和现场应用表明,该工具创新性强,综合性能安全可靠,能很好地满足φ244.5 mm(95/8英寸)套管完井生产的需要。     

岩石爆破中爆炸能量分布规律的研究现状

根据岩石爆破中破岩机理的发展状况,分类概括了爆炸能量分布规律的研究现状,指出存在的问题,提出了进一步发展的方向和前景。     

影响有线数字电视机顶盒发展的因素

从用户需求、节目源、价格、资金、行业体制等方面论述了影响有线数字电视机顶盒发展的因素。     

水资源综合利用与管理规划初步研究

通过对水资源可持续利用规划进行的宏观、中观、微观三个层次的研究提出了管理规划的模型．利用该模型，可通过对环境经济的评价促进我国社会经济可持续发展目标的实现．本研究从加强水资源管理，重点要从水资源产权管理、水资源开发利用规划以及水资源合理配置几方面着手，提出应建立健全水资源管理的法律、政策和协调机制，加大水价改革力度，提高水价对促进水资源合理利用的经济杠杆作用，促进水资源的可持续利用．