Demonstration of a high throughput on-board hydrogen generation reactor system using aluminum coil as fuel for a vehicle

A novel on-board hydrogen generation concept using Al coil with NaOH was investigated. The reaction rate was successfully controlled by introducing a pumping system for the NaOH solution. The time for the flow to develop fully was mainly dependent on the solution temperature, and the fastest start time recorded was 60 sec at a solution temperature of 70°C. The maximum H₂ generation rate was 200 L min^–1 with a prototype design of the on-board hydrogen generation system 1/8 times the size of a full-size reactor. The H₂ generation process coupled with the solution pumping system was simulated with three-dimensional fluid dynamic software, and the calculated H₂ flow and temperature rise of the system were validated with experimental data.     

Optimisation algorithms for spatially constrained forest planning

We compared genetic algorithms, simulated annealing and hill climbing algorithms on spatially constrained, integrated forest planning problems. There has been growing interest in algorithms that mimic natural processes, such as genetic algorithms and simulated annealing. These algorithms use random moves to generate new solutions, and employ a probabilistic acceptance/rejection criterion that allows inferior moves within the search space. Algorithms for a genetic algorithm, simulated annealing, and random hill climbing are formulated and tested on a same-sample forest-planning problem where the adjacency rule is strictly enforced. Each method was randomly started 20 times and allowed to run for 10,000 iterations. All three algorithms identified good solutions (within 3% of the highest found), however, simulated annealing consistently produced superior solutions. Simulated annealing and random hill climbing were approximately 10 times faster than the genetic algorithm because only one solution needs to be modified at each iteration. Performance of simulated annealing was essentially independent of the starting point, giving it an important advantage over random hill climbing. The genetic algorithm was not well suited to the strict adjacency problem because considerable computation time was necessary to repair the damage caused during crossover.     

Study of chest injuries to 3-year-old child occupants seated in impact shield and 5-point harness CRSs

Objective: The objective of this study was to investigate whether the 5-point harness or the impact shield child restraint system (CRS) or both have the potential to cause chest injuries to children. This is determined by examining whether the loading to the chest reaches the internal organ injury threshold for children.

Method: The chest injury risk to a child occupant in a CRS was investigated using Q3 dummy tests, finite element (FE) simulations (Q3 dummy and human models), and animal tests. The investigation was done for 2 types of CRSs (i.e., the impact shield CRS and 5-point harness CRS) based on the UN R44 dynamic test specifications.

Results: The tests using a Q3 dummy indicated that although the chest deflection of the dummy in the impact shield CRS was large, it was less than the injury threshold (40 mm). Computational biomechanics simulations (using finite element FE analysis) showed that the Q3 dummy's chest is loaded by the shield and deforms substantially under this load. To clarify whether chest injuries due to chest compression can occur with an impact shield or with the 5-point harness CRS, 7 experiments were performed using Tibetan miniature pigs with weights ranging from 9.7 to 13 kg. Severe chest and abdominal injuries (lung contusion, coronary artery laceration, liver laceration) were found in the tests using the impact shield CRS. No chest injuries were present when using the 5-point harness CRS.

Conclusion: When using the impact shield CRS, the chest deformed substantially in dummy tests and FE simulations, and chest and abdominal injuries were observed in pig tests. It is possible that these chest injuries could also occur to child occupants sitting in the impact shield CRS.     

Antecedents and consequences of satisfaction with work–family balance: A moderating role of perceived insider status

This study developed a moderated mediation model to investigate how family‐supportive paid leave and supervision affect employees' satisfaction with work–family balance and in turn their affective organizational commitment and supervisor‐directed organizational citizenship behavior depending on their perceived insider status in the organization. Our analysis of data collected from 118 employee–supervisor dyads in Korean organizations revealed that satisfaction with work–family balance mediated the linkages from family‐supportive supervision to affective organizational commitment and supervisor‐directed organizational citizenship behavior, and the linkage from family‐supportive paid leave to affective organizational commitment. Results further showed that the entire mediational process for family‐supportive supervision was more pronounced for those who perceived themselves to be an insider of their organizations, while the same pattern was not found for the meditational process related to family‐supportive paid leave. Our findings provide theoretical implications for work–family balance research and offer practical suggestions to make employees satisfied with work–family balance.     

N-甲基羟胺盐酸盐的热分解机理的理论研究

为深入研究N-甲基羟胺盐酸盐(NMHH)热分解的反应特征,应用密度泛函理论,在w B97xd/6-311++g(2df,2pd)水平下,对NMHH的初步分解产物N-甲基羟胺(NMHA)及质子化的NMHA热分解反应中涉及的反应物、过渡态、中间体、产物的几何结构和能量情况进行了优化计算,提出了可能的热分解路径。结果表明,NMHA与质子化NMHA均存在两种热分解路径。NMHA在两条路径下分解需越过的能垒为250.75 k J/mol与428.64 k J/mol,而质子化NMHA在对应分解路径下需要越过的能垒分别为217.19 k J/mol与286.77k J/mol。在对应路径下质子化NMHA分解需越过的能垒明显低于NMHA的直接分解,并且随着反应的持续进行,质子化的NMHA的形成和分解将越来越容易发生。这表明NMHH的分解具有自催化特征,与试验结果吻合。     

Primary production and rain use efficiency across a precipitation gradient on the Mongolia Plateau

Understanding how the aboveground net primary production (ANPP) of arid and semiarid ecosystems of the world responds to variations in precipitation is crucial for assessing the impacts of climate change on terrestrial ecosystems. Rain-use efficiency (RUE) is an important measure for acquiring this understanding. However, little is known about the response pattern of RUE for the largest contiguous natural grassland region of the world, the Eurasian Steppe. Here we investigated the spatial and temporal patterns of ANPP and RUE and their key driving factors based on a long-term data set from 21 natural arid and semiarid ecosystem sites across the Inner Mongolia steppe region in northern China. Our results showed that, with increasing mean annual precipitation (MAP), (1) ANPP increased while the interannual variability of ANPP declined, (2) plant species richness increased and the relative abundance of key functional groups shifted predictably, and (3) RUE increased in space across different ecosystems but decreased with increasing annual precipitation within a given ecosystem. These results clearly indicate that the patterns of both ANPP and RUE are scale dependent, and the seemingly conflicting patterns of RUE in space vs. time suggest distinctive underlying mechanisms, involving interactions among precipitation, soil N, and biotic factors. Also, while our results supported the existence of a common maximum RUE, they also indicated that its value could be substantially increased by altering resource availability, such as adding nitrogen. Our findings have important implications for understanding and predicting ecological impacts of global climate change and for management practices in arid and semiarid ecosystems in the Inner Mongolia steppe region and beyond.     

Temporal analysis of population genetic composition in the overexploited Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis>

The Japanese eel has dramatically declined in Asia since the 1970s. Over the past two decades, glass eel productivity in Taiwan has decreased, but is highly variable among each year catch, though the cause for this is unknown. The impact of both population decline and instability on genetic diversity, however, is unknown. In this study, we investigated changes in allele frequencies of Japanese eel recruitment events over the past 20 years using six polymorphic microsatellite DNA loci. Specimens of glass eels were collected yearly from a single location in northern Taiwan from 1986 to 2007. Overall genetic differentiation among all samples was very low but significant (F_ST = 0.002, P = 0.002), and only 2 out of 120 pairwise tests were significant. The relationship between genetic and temporal distance showed a slight but insignificant correlation (R² = 0.03, P = 0.0504). There were no overall significant differences in allelic richness (P = 0.35) or genetic heterozygosity (P = 0.73) among annual recruitment events. No apparent loss of genetic diversity and occurrence of a genetic bottleneck for eel populations were observed. Estimates of the effective population size (N_e) generally exceeded 500, although confidence intervals were very wide. While El Niño /Southern Oscillation (ENSO) events had little impact on genetic diversity, they may account for the annual fluctuation in glass eel catch. These results indicate long-term stability of genetic diversity in the Japanese eel with little evidence for sweepstakes recruitment.     

城市地表灰尘颗粒体积分形特征及其吸附性

以地表灰尘颗粒分析数据为基础,运用分形模型,分析了芜湖市高新技术开发区地表灰尘颗粒的分维数.结果表明:19个地表灰尘样品的粒径较粗,粒径的平均值多出现在140～230 gm之间,峰值多出现在200～400 μm之间;分维数为2.5392～2.7408.平均值为2.665 7,pH值为7.97～12.36,平均值为10.22,呈较强的碱性.分维数与pH值之间的相关系数r=-0.221 0,相关性不明显;地表灰尘分维数对吸附性的影响效果不明显.     

泥石流V型排导槽防淤设计方法及其应用研究

排导槽是泥石流治理常用的工程措施,泥石流若在槽内淤积,将极大影响排导槽防治效果。目前国内现行规范中没有关于排导槽淤积情况计算的相关条款,导致排导槽被泥石流淤埋的工程事故时有发生。鉴于此,分析了排导槽淤堵的常见原因,对现有的一些排导槽淤积验算公式进行了分析和整理,提出了一套基于槽宽验算、槽内泥深及流速验算等公式的排导槽防淤设计验算方法。该方法在雅(安)泸(沽)高速公路沿线某泥石流沟V型排导槽淤埋事故的处理中进行了应用,重建的排导槽经受了2011年6月17日特大暴雨形成的泥石流的考验,说明该方法实施效果良好,可供相关研究与设计参考。     

装配式综合管廊光纤智能螺栓受力原型试验研究

掌握装配式综合管廊的螺栓节点在土体回填、加载、卸载等工况中所承受的应力变化,对于准确评价管廊施工和运营期的稳定性有着重要的作用。针对常规的监测手段难以满足综合管廊在施工及运营期间安全监测要求的瓶颈,基于开发的光纤光栅(FBG)智能螺栓应力计,对南京江北新区某综合管廊的建设过程进行原型试验研究。现场监测结果表明:FBG螺栓应力计监测数据与管廊的连接位置、施工工况、堆载大小及位置等有关。在管廊上部堆载从0增加至4 000 kN的过程中,FBG螺栓应力计测试数据处于安全阈值,表明其具有足够的螺栓预紧度;根据相关规范,螺栓所受的最大应力满足设计使用要求,保证了管廊结构的承载力处于安全范围。本研究充分验证了光纤传感技术在装配式综合管廊受力变形监测中的有效性,未来值得推广应用。