Expansion of the US wildland–urban interface

For at least two decades, expansion of low-density residential development at the wildland–urban interface has been widely recognized as a primary factor influencing the management of US national forests. We estimate the location, extent, and trends in expansion of the wildland–urban interface (WUI) in the continental United States. We mapped the WUI by determining the intersection of housing density classes computed from refined US Census data with a map of wildfire hazards based on broad forest types using definitions of WUI from the Federal Register. Our methods allowed us to provide a more spatially precise estimation of the WUI that better reflects development patterns of interest to forest land managers. We defined three wildfire hazard classes based on vegetation type. “High” severity applies to vegetation types in which stand-replacing fires dominate both historical and recent fire regimes, e.g., lodgepole pine forest. “Low” severity applies where fuels and climate foster mostly low-intensity fires, e.g., aspen-birch forest. “High (historically low or variable)” applies to vegetation types in which fires historically were of low or variable intensity, but recently have often burned at high intensity because of a century of fire exclusion, e.g., southwestern ponderosa pine forest. In 2000, the WUI that includes a 3.2 km community protection zone occupied 465,614 km², and contained over 12.5 million housing units. This is an expansion of over 52% from 1970, and by 2030 the WUI is likely to expand to at least 513,670 km² with the greatest expansion occurring in the intermountain west states. Roughly 89% of the WUI is privately owned land and about 65% of the WUI occurs in high or high (historically low or variable) severity fire regime classes.     

Probabilistic Modelling in the Water Industry

The water authorities in England and Wales, which have now become water companies, recently had to provide anticipated costs for maintaining the water supply and sewerage systems over the next 20 years. Probabilistic models and statistical inference provide an opportunity to quantify the uncertainty in such exercises. Their use in a study undertaken by a water authority in the north-east of England is described and illustrated with interim data which were available at an early stage in the exercise.     

12Cr17Ni7不锈钢中大型夹杂物的分析

对12Cr17Ni7(ASTM/301)不锈钢连铸坯中大型夹杂物的形貌和化学成分进行分析。结果表明:该夹杂物是由Fe、Cr、Ni、Mn等金属组成,且有一定的韧性。分析认为该夹杂物是在连铸过程中,在结晶器上较长时间凝结的钢液滴在表面受到氧化后被钢水冲入钢液,这种没有上浮的半凝固态的钢液滴,在连铸后进入铸坯中形成外来的金属夹杂物;对此提出具体的控制措施。     

一种林间自装卸粉碎机底盘设计与分析

针对目前移动式林间粉碎设备存在的问题,提出了一种林间自装卸粉碎机底盘.介绍了其行走系统、车架、支撑系统、液压系统、制动系统、转向系统等.通过CATIA软件对该底盘进行了主要部件的三维建模和装配,并对底盘进行了强度分析.     

地铁明挖区间废水泵房破除改造方案研究

已投入运营的武汉地铁4号线明挖区间右线废水泵房侵入拟建5号线盾构区间限界,需对其进行破除改造。通过对1 m、3 m及5 m破除进尺长度时各施工工况进行数值模拟分析,获得不同破除进尺长度时各施工工况下明挖区间结构及土体变形情况。分析结果表明:采用5 m进尺长度的破除施工方案是可靠的、合理的;破除所引起的结构变形主要集中在4号线区间右线结构顶、底板,破除结构前应于紧邻破除区5.0 m范围内设置水平、垂直向临时钢管支撑。数值分析所得数据和结论不仅为破除改造时的支护体系设计提供依据,也可为类似工程提供有益的借鉴。     

Whole model empirical validation on a full-scale building

This paper describes an empirical validation study undertaken on two identical full-size buildings within the scope of the IEA ECB Annex 58 project. Details of the experimental configuration and monitoring are included, together with results from measurements and from predictions made by 21 modelling teams using commercial and research simulation programmes. The two-month, side-by-side experiment was undertaken on buildings with high levels of thermal mass and in a period with high solar gains. The detailed specification and associated measurement data provide a useful empirical validation dataset for programme testing. Results from the modelling demonstrate good agreement between measured data and predictions for a number of programmes, in both absolute predictions of temperatures and heat inputs as well as dynamic response. On the other hand, a significant number of user input errors resulted in poor agreement for other programmes, especially in the blind validation phase of the modelling methodology.     

基于CREAM的航天发射场人因可靠性定量分析方法研究

以我国航天发射场安全评估为背景,基于认知可靠性和失误分析方法(CREAM),开展航天发射场人因可靠性(HRA)定量分析方法研究。首先结合航天发射场特点对共同绩效条件(CPC)进行改进,之后采用模糊方法处理CPC到控制模式之间的映射关系,提出了环境影响因子值的概念,提出了航天发射场HRA定量分析流程,最后针对火箭吊装过程进行了实例分析。     

基于空间分析的城市火灾风险评估与应用——以西安为例

城市消防是城市中重要的安全保障体系之一,本文从消防重点地区、人口密度、高层建筑分布、大型人流密集的地下空间等风险要素的空间分析入手,探索城市火灾风险评估的方法及其应用,旨在为编制城市消防专项规划、城市消防设施建设和城市消防安全管理提供扎实、科学的依据。     

磨损随机过程建模及实例分析

针对磨损过程的动态性和随机性,提出一种构件磨损随机过程建模方法,为磨损构件的可靠性分析和寿命预测提供基础。基于平稳随机过程,给出了磨损随机过程建模基本流程;以Ar-chard磨损公式为例,推导了任意时刻磨损量的分布函数,从而能够评估磨损构件的动态可靠度和概率失效时间;结合活塞气环的实测数据,建立磨损随机过程模型,并给出抗磨损可靠度随行驶里程的变化规律。通过算例发现,磨损随机过程模型与实际相符,而考虑稳态磨损过程的磨损率为随机变量,计算结果偏保守。这样,为工程构件磨损的定量评估探索新的途径。     

锂离子电池负极浆料稳定性测试

利用流变仪在相同频率下测试相同设备和配方以及不同工艺制备的石墨体系负极浆料的线性黏弹区(LVR)长度和内聚能(CE),以评价浆料的稳定性。该方法耗时短(不超过15 min)、范围广,结果准确,实验的重现性和实用性好。对相同负极浆料平行测试3次,LVR长度和CE的标准偏差分别为1.108%和0.009%,可取代传统的负极浆料稳定性的测试方法。