Biomass for Fuel Cells: A Technical and Economic Assessment

Fuel cells can be highly efficient energy conversion devices. However, the environmental benefit of utilising fuel cells for energy conversion is completely dependent on the source of the fuel. Hydrogen is the ideal fuel for fuel cells but the current most economical methods of producing hydrogen also result in the production of significant amounts of carbon dioxide. Utilising biomass to produce the fuel for fuel cell systems offers an option that is technically feasible, potentially economically attractive and greenhouse gas neutral. High-temperature fuel cells that are able to operate with carbon monoxide in the feed are well suited to these applications. Furthermore, because they do not require noble metal catalysts, the cost of high-temperature fuel cells has the greatest potential to become competitive in the near future compared to other types of fuel cells. It is, however, extremely difficult to assess the economic feasibility of biomass-fuelled fuel cell systems because of a lack of published cost information and uncertainty in the predicted cost per kW of the various types of fuel cells for large volume production methods. From the scant information available it appears that the current cost for fuel-cell systems operating on anaerobic digester gas is about US$2,500 per kW compared to a target price of US$1,200 required to compete with conventional technologies.     

基于MODIS的雅鲁藏布江流域干旱动态监测及对植被胁迫作用的研究

基于MODIS数据利用垂直干旱指数模型和重心模型分析了2011年4月~2012年4月的雅鲁藏布江流域干旱动态变化,并就干旱对植被的胁迫作用做了进一步探讨。研究发现：（1）干旱强度减弱区主要分布于雅鲁藏布江流域的中部,而干旱强度增强区则主要集中于该流域的上游及下游地区;（2）2012年4月份雅鲁藏布江流域的总体干旱强度相比2011年4月有所加重,轻度干旱、重度干旱区均有所增长,而湿润区则有一定减小。干旱强度加重较大的区域主要分布于拉萨河流域及＞3 000～4 000 m、＞4 000～5 000 m高度带;（3）雅鲁藏布江流域的NDVI与PDI的重心迁移具有很好的负相关性,说明其干旱动态变化对植被具有较明显的胁迫作用     

气象干旱诊断评估方法及其在长江中下游地区的应用

干旱是具有一定持续时间和影响范围双重特性的气候异常事件,为客观反映干旱事件的综合影响及演变特征,借鉴“时间-面积”函数的概念,基于综合气象干旱指数建立了气象干旱评估指标和模式,对干旱的时空特征进行了系统的量化表征和可视化表达,并以长江中下游地区为例进行了应用检验。结果表明提出的指标方法能够客观识别和反映出历史典型干旱事件及其强度,对干旱时空分布细节特征的诊断直观具体,对干旱过程起止时间、发展速度、烈度、强度的诊断准确合理。该方法操作简便且物理意义清晰,对省市级、流域及国家级干旱监测评估业务具有良好的应用价值。     

湖北省旱涝灾害的若干统计特征及对农业生产的影响

着重分析了湖北省４０多年来旱涝灾害的若干统计特征及其对农业生产的影响，指出了旱涝灾害的演变趋势，以及人类活动对灾害加剧的主导作用，为防、抗旱涝灾害提供参考。     

湖北省畜禽粪便温室气体减排潜力分析

畜禽粪便是农业温室气体的重要排放源.合理的粪便管理方式可有效降低温室气体排放,同时减少环境污染.为明确不同养殖模式下适宜的粪便管理方式对温室气体减排的有效性,以湖北省为案例地,针对不同畜禽的粪便特征、区域自然条件和畜禽养殖模式等,筛选适宜的粪便管理方式;运用政府间气候变化专门委员会提出的畜禽粪便温室气体排放因子测算模型,在优化管理方式的基础上进行排放因子预测,估算由粪便管理方式改进所带来的减排潜力.结果表明,粪便管理经优化后畜禽粪便温室气体排放减少1.98~357.82 kg·头-1·a-1(以CO2当量计).根据养殖规模发展趋势预测,至2020年全省畜禽粪便优化管理所带来的减排潜力可达322.78万t(以CO2当量计).不同地区间减排效果则与当地养殖规模、养殖结构、养殖模式及适宜的畜禽粪便管理方式密切相关;畜禽种类间粪便特性的不同是其CH4和N2O减排效率迥异的主要原因;规模化养殖粪便管理方式优化是实现区域温室气体减排的重点.结合区域自然条件和畜禽养殖特征等,筛选适宜的粪便管理方式是实现区域温室气体减排的有效措施.     

汉江中下游流域降水时空规律分析及干旱预测

近年来汉江中下游流域连续发生干旱,随着越来越多跨流域调水工程的实施,势必加剧该流域的旱情。所以,研究汉江中下游流域降水序列及干旱预测显得尤为重要。应用汉江中下游12个站点50年(1963—2012年)降水资料,通过克里金插值法和一元线性回归方程分析其降水的空间分布及时间变化规律。选取1963—2006年的数据建立灾变预测模型GM(1,1),预测该区域未来一定时期内可能发生干旱的年份。经过多种检验,模型精度较高,预测结果也基本与实际相符。     

Exploratory field trial of motorcycle autonomous emergency braking (MAEB): Considerations on the acceptability of unexpected automatic decelerations

Objective: Autonomous emergency braking (AEB) acts to slow down a vehicle when an unavoidable impending collision is detected. In addition to documented benefits when applied to passenger cars, AEB has also shown potential when applied to motorcycles (MAEB). However, the feasibility of MAEB as practically applied to motorcycles in the real world is not well understood.

Methods: In this study we performed a field trial involving 16 riders on a test motorcycle subjected to automatic decelerations, thus simulating MAEB activation. The tests were conducted along a rectilinear path at nominal speed of 40 km/h and with mean deceleration of 0.15 g (15% of full braking) deployed at random times. Riders were also exposed to one final undeclared brake activation with the aim of providing genuinely unexpected automatic braking events.

Results: Participants were consistently able to manage automatic decelerations of the vehicle with minor to moderate effort. Results of undeclared activations were consistent with those of standard runs.

Conclusions: This study demonstrated the feasibility of a moderate automatic deceleration in a scenario of motorcycle travelling in a straight path, supporting the notion that the application of AEB on motorcycles is practicable. Furthermore, the proposed field trial can be used as a reference for future regulation or consumer tests in order to address safety and acceptability of unexpected automatic decelerations on a motorcycle.     

云南省马鞍山沟泥石流危险度评价

为了保证金沙江某码头工程的顺利进行,特对马鞍山沟泥石流做危险度评价。根据对马鞍山沟泥石流的调查与分析,结合前人的研究成果,选取了一次泥石流最大冲出量、松散固体物质储量、最大漂砾粒径、最大容重、最大12小时暴雨量、流域最大相对高差、泥石流发生频率、流域面积等8个危险因子。采用模糊综合评判法,建立评价因子隶属函数与模糊矩阵;依据最大隶属度原则得出所属危险度;结果显示:马鞍山沟泥石流的危险度为中度危险,在强降雨激发下有可能发生泥石流灾害。     

基于地震易损性的连续梁桥减隔震方案研究

减隔震措施的合理配置是高速铁路地震经济性目标控制的关键。为了对采用不同减隔震装置的高速铁路连续梁桥抗震性能进行量化研究,基于桥梁系统地震易损性分析,选用4种减隔震方案进行对比分析。4种方案分别为:全桥抗震设计方案（方案1）、全桥双曲面球型隔震支座+粘滞阻尼器方案（方案2）、中墩摩擦摆+边墩普通支座与阻尼器配合方案（方案3）和全桥摩擦摆+边墩阻尼器方案（方案4）。结果表明:高烈度高速铁路桥梁须通过减隔震设计才能满足抗震设防目标,综合经济性和抗震性能2方面因素,方案4有效降低了结构内力响应和位移响应,为所列方案中的最优方案。     

Agricultural Adaptation to Drought for Different Cropping Systems in Southern China under Climate Change

This study investigates agricultural adaptation to drought for different cropping systems in southern China. The study area was divided into three regions: South China (SC), South of the Yangtze River (SYR), and Southwest China (SWC). An index of agricultural adaptation to drought (D) was established. Our findings indicated that the average total crop water demand varied greatly among the regions from 1961 to 2010 in southern China. The maximum value was found in the SC region, followed by the SYR and SWC regions. The effects of droughts on different crops were noticeable. Frequent droughts were recorded in late rice than in early rice in the SC and SYR regions. Droughts in the SWC region mainly affected winter wheat. Moreover, the effects of droughts on crops varied during different growth stages. More frequent and serious droughts occurred during the crop critical flowering stage. Particularly, the frequency of moderate and severe droughts for late rice in the SYR region was 62% during the critical flowering stage. For the SC and SYR regions, the D values of early rice (0.29 and 0.29) were lower than that of late rice (0.31 and 0.33), respectively. For the SWC region, the D values of winter wheat and rice were both low, with averages of 0.16 and 0.29, respectively. Our study provides interesting insights for improving the drought defense abilities for different cropping systems by changing crop planting proportion on a regional scale in China.