开敞空间可燃气云爆炸冲击波超压及灾害动力响应研究评述

为了进一步梳理和分析开敞空间可燃云爆炸冲击波超压传播规律及灾害动力响应方面的各项研究成果,推进可燃气体爆炸安全防控,减少人员伤亡和经济损失。在分析现有研究的基础上,总结开敞空间可燃气云爆炸冲击波超压传播规律及灾害动力响应研究等方面存在的不足,提出开敞空间多元混合气体爆炸冲击波超压传播规律研究、多影响参数下可燃气云爆炸冲击波超压传播规律定量分析、基于可燃气云爆炸冲击波超压作用下的承载体动力响应等未来研究的关键技术问题。     

Law of variation for low density polyethylene dust explosion with different inert gases

To reveal the effects of different inert gases on explosion characteristics during low density polyethylene (LDPE) dust explosion and optimize the explosion-proof process, eight N₂ (CO₂)/air mixed inerting conditions were experimentally studied. Typical inerting conditions with 12 L cylindrical explosive tank were used to study the characteristics on the flame propagation. The thermogravimetric analysis with related theories were used to further explain the mechanism and quantities in low density polyethylene (LDPE) dust explosion with different inert gases. The results showed that the reduction of O₂ concentration could effectively delay the progress of flame growth process and weaken the effect of dust combustion reaction. The flame growth process of condition (N₂/air (18% O₂)) was 2.05 times slower than that of the non-inert condition. The explosion strength was obviously reduced, and the characteristic parameters such as explosion pressure and flame propagation speed were also affected by the decrease of O₂ concentration. For LDPE powder, the smaller the median diameter, the greater the explosion intensity and the lower the limiting oxygen content (LOC). The LOC with CO₂ was usually higher than that with N₂ and the effect of CO₂ was significantly better than N₂ in inerting.     

植物离体快繁中若干关键技术的预防措施

菌类污染，褐变现象和玻璃化现象，是植物离体快繁中的三大难题，现已严重影响植物离体培养与快繁体系的建立．本文较详细地论述了这三大难题出现的原因，进而提出预防及控制的措施。     

Hough变换在PCB在线检测系统的应用

在印刷电路板(PCB)视觉检测系统中,图象边缘提取的质量和对瑕疵图象边缘的快速而准确的识别是达到实时检测的关键因素,Hough变换是一种应用非常广泛的图像边缘检测技术,运用快速的Hough变换方法,来完成PCB检测的圆心定位和半径测定,并通过针时PCB在线检测的具体应用情况加以改进并应用,实验分析表明,该算法在PCB在线检测的可行性和优越性.图5,参5.     

实数编码遗传算法的评述

遗传算法是一种基于自然选择和遗传变异等生物进化机制的全局优化搜索算法．使用实数表示基因的实数编码遗传算法常用于求解连续函数优化等问题．本文阐述了实数编码遗传算法研究的有关工作进展，讨论了算法框架及特点，对实数编码遗传算法中常用的选择、交叉和变异算子进行了比较全面的形式化描述，并介绍了其未来研究方向．     

River water quality management model using genetic algorithm

Conventional mathematical programming methods, such as linear programming, non linear programming, dynamic programming and integer programming have been used to solve the cost optimization problem for regional wastewater treatment systems. In this study, a river water quality management model was developed through the integration of a genetic algorithm (GA). This model was applied to a river system contaminated by three determined discharge sources to achieve the water quality goals and wastewater treatment cost optimization in the river basin. The genetic algorithm solution, described the treatment plant efficiency, such that the cost of wastewater treatment for the entire river basin is minimized while the water quality constraints in each reach are satisfied. This study showed that genetic algorithm can be applied for river water quality modeling studies as an alternative to the present methods.     

The Value of Biodiversity in Reserve Selection: Representation, Species Weighting, and Benefit Functions

Abstract:  The limited availability of resources for conservation has led to the development of many quantitative methods for selecting reserves that aim to maximize the biodiversity value of reserve networks. In published analyses, species are often considered equal, although some are in much greater need of protection than others. Furthermore, representation is usually treated as a threshold: a species is either represented or not, but varying levels of representation over or under a given target level are not valued differently. We propose that a higher representation level should also have higher value. We introduce a framework for reserve selection that includes species weights and benefit functions for under- and overrepresentation (number of locations for each species). We applied the method to conservation planning for herb-rich forests in southern Finland. Our use of benefit functions and weighting changed the identity of about 50% of the selected sites at different funding levels and improved the representation of rare and threatened species. We also identified a small area of additional land that would substantially enhance the existing reserve network. We suggest that benefit functions and species weighting should be considered as standard options in reserve-selection applications.     

Propagation of olfactory information within the honeybee hive

Transfer of information about food source characteristics within insect societies is essential to colony-foraging success. The food odor communicated within honeybee hives has been shown to be important for food source exploitation. When successful foragers return to the nest and transfer the collected nectar to hive mates through mouth-to-mouth contacts (trophallaxis), potential recruits receiving these samples learn the food odor by associative learning. The food then becomes rapidly distributed among colony members, which is mainly a consequence of the numerous trophallaxes between hive-mates of all ages during food processing. We tested whether the distribution of food among hive mates causes a propagation of olfactory information within the hive. Using the proboscis extension response paradigm, we show that large proportions of bees of the age groups representing the main worker castes, 4 to 9-day-old bees (nurse-aged bees), 12 to 16-day-old bees (food processor-aged bees), and actual foragers (about 17+ day old bees) associatively learn the food odor in the course of processing food that has been collected by only a few foragers. Results further suggest that the information is shared more or less equally between bees of the three age groups. This shows that olfactory information about the flower species exploited by foragers is distributed within the entire colony and is acquired by bees of all age groups, which may influence many behaviors inside and outside the hive.     

地面运动转动分量的合成方法

假设近场地面运动由体波产生（忽略面波的影响）,根据弹性半空间的平面谐波理论,提出了利用平动分量加速度记录合成地面转动加速时程的方法。该方法考虑了由于实际介质的不均匀性而产生的地震波频散现象。     

三维铝型材挤压模多参数优化

以一个导流组合模为例,利用神经网络建立模具参数的数学模型,用遗传算法对参数优化。其中由正交法设计得到实验样本,由软试模提取模具的SDV值,将其作为优化目标。最终实验结果与优化值吻合,为建立和控制挤压模参数提供了一种行之有效的手段。