Acoustic methods for locating fire spread paths in old buildings

It has been well known for a long time that many fires in old buildings spread rapidly. The cause of this is often the penetration of smoke gas through ducts or unknown cracks or cavities in the building structure. In order to describe and analyse this problem, a number of non-destructive methods, which could be used to identify such possible smoke distribution paths in walls and floor structures, have been studied. It was found that an acoustical method showed promising results. This method was used in a couple of experiments at the Royal Palace in Stockholm and later on in laboratory experiments. The results from these experiments show that the use of standardised sound insulation measurements, together with listening tests, has the potential to locate possible fire distribution paths. Furthermore, some properties of a path, e.g. a crack length, can be deduced, a fact which can used as an additional help to locate the path.     

Conduction paths of backbones for thermal enhancement of nanocomposite phase change materials

Thermal energy storage (TES) based on phase change materials (PCMs) has become a research hot spot due to its high energy storage density and maintained operating temperature during the phase change. However, as PCM has a poor thermal conductivity that can be as low as 0.2~0.5 W/m· K, the charging/discharging processes of PCM modules are significantly restrained, which severely affects the application of the TES technology in industrial sectors. This study concerns the improvement of the effective thermal conductivity of composite PCM formed by adding nanoparticles with high thermal conductivity into different PCMs. A theoretical model is established to reveal the intrinsic mechanism for the promotion of thermal conductivity of composite PCM consisting of nanoparticles. The results show that aggregation and interfacial thermal resistance are the main reasons for the change of the thermal conductivity. By forming effective conduction paths composed of backbones in the composite PCM, the average thermal conductivity can be improved significantly, which can be as high as 10~50 W/m· K with a wide range of volume fraction of the additives.     

铝土矿正浮选精矿过滤助滤剂的研究及应用

实验室研究了铝土矿正浮选精矿过滤的助滤剂,工业应用证明有效地解决了由于铝土矿品位的下降,铝土矿正浮选精矿过滤困难,过滤设备产能低下的难题.     

Direct Observation of Ag Filamentary Paths in Organic Resistive Memory Devices

We demonstrate bipolar switching of organic resistive memory devices consisting of Ag/polymer/heavily‐doped p‐type poly Si junctions in an 8 × 8 cross‐bar array structure. The bistable switching mechanism appears to be related to the formation and rupture of highly conductive paths, as shown by a direct observation of Ag metallic bridges using transmission electron microscopy and energy‐dispersive X‐ray spectroscopy. Current images of high‐ and low‐conducting states acquired by conducting atomic force microscopy also support this filamentary switching mechanism. The filamentary formation can be described by an electrochemical redox reaction model of Ag. Our results may also be applied to other kinds of organic materials presenting similar switching properties, contributing to the optimization of device scaling or memory performance improvement.     

Optimization of aeromedical base locations in New Mexico using a model that considers crash nodes and paths

In a recent paper, Tokar Erdemir et al. (2008) introduce models for service systems with service requests originating from both nodes and paths. We demonstrate how to apply and extend their approach to an aeromedical base location application, with specific focus on the state of New Mexico (NM). The current aeromedical base locations of NM are selected without considering motor vehicle crash paths. Crash paths are the roads on which crashes occur, where each road segment has a weight signifying relative crash occurrence. We analyze the loss in accident coverage and location error for current aeromedical base locations. We also provide insights on the relevance of considering crash paths when selecting aeromedical base locations. Additionally, we look briefly at some of the tradeoff issues in locating additional trauma centers vs. additional aeromedical bases in the current aeromedical system of NM. Not surprisingly, tradeoff analysis shows that by locating additional aeromedical bases, we always attain the required coverage level with a lower cost than with locating additional trauma centers.     

造纸生产线测控系统主要干扰及抗干扰措施

本文以造纸生产线中自动控制系统的干扰问题作为研究对象,分析给系统带来干扰的主要形式、耦合途径和危害性,并提出有效的抗干扰措施.     

Search for minimal paths in modified networks

The problem of searching for all minimal paths (MPs) in a network obtained by modifying the original network, e.g. for network expansion or reinforcement, is discussed and solved in this study. The existing best-known method to solve this problem was a straightforward approach. It needed extensive comparison and verification, and failed to solve some special but important cases. Therefore, a more efficient, intuitive and generalized method to search for all MPs without an extensive research procedure is proposed. In this presentation, first we develop an intuitive algorithm based upon the reformation of all MPs in the original network to search for all MPs in a modified network. Next, the computational complexity of the proposed algorithm is analyzed and compared with the existing methods. Finally, examples illustrate how all MPs are generated in a modified network based upon the reformation of all of the MPs in the corresponding original network.     

大孔树脂精制竹蔗烟熏液的工艺研究

对6种大孔树脂精制竹蔗烟熏液的效果进行比较,以烟熏液中的代表成分酚类物质和3,4-幕并芘为考察指标,对大孔树脂精制烟熏液的工艺进行筛选.结果表明:6种树脂对羰基化合物基本不吸附,静态吸附过程中,温度对树脂吸附酚类物质和3,4-幕并芘影响不大,烟熏液原液10mL,加入2g的树脂对3,4-苯并芘吸附效果最好,采用30mL体积分数95％乙醇进行解析,酚类物质和3,4-苯并芘的解析率最高,其中,XAD-4树脂精制烟熏液效果最佳.     

建筑的体验——浅析阿尔瓦罗·西扎的三个建筑作品

阿尔瓦罗·西扎是一个注重建筑体验的建筑师,漫步在他设计的建筑中,我们可以感受到内部的漫步路径与建筑的表现形态、周边的景观都有很大关系.通过解析他近年完成的三个作品来了解它们之间的相互关系,从而了解西扎在建筑设计中的侧重点.     

基于D-K算法的煤矿水灾多最优路径研究

矿井水灾时选择合理的逃生路线,需要考虑水及巷道其他因素的影响,引入当量长度来求解到达逃生地点用时最短最安全的路径。Dijkstra算法可求解从源节点到目标节点的最短路径,K则最优路径算法可求解从源节点到某一目标节点的前N条最优路径,矿井水灾时,为了避免拥挤,同一地点工作的人员可选择多个逃生井口进行逃生,但从源节点到某一目标节点的前N条最优路径并不一定是到其他逃生井口的前N条最优路径,基于这种思路,在Dijkstra算法的基础上,提出一种从源节点到其他所有逃生节点的前N条最优路径的新方法,并结合矿井具体实例,与Dijkstra算法和K则最优路径算法比较,用MATLAB仿真实现。