基于突变理论的盾构下穿危旧房屋及河流段风险评价与控制方法研究

为了综合评价盾构下穿危旧房屋及河流段风险,结合软土土质特点,在对已有评价模型分析的基础上,针对风险评价普遍存在的问题,借鉴突变理论,确定盾构施工风险突变评价法步骤,将各因素归纳为工程地质、勘察设计施工、周边环境和水文地质四大指标,并对其进行分解,构建风险评价指标体系及等级标准,利用突变理论对工程实例进行评价,得到该区间盾构施工风险等级为极高风险,评估的结果较好地反映了工程的实际情况。基于风险评价结果,在盾构下穿过程,采取合理设定土压力、调节盾构推进速度和注浆压力等措施,实时动态监控地表沉降的变化和盾构施工关键参数,所得成果验证了突变理论风险评价的实用性和有效性。     

灾害与经济增长关系的定量分析

本文以哈罗德－多马经济增长模型为基础，初步估计了灾害直接损失对经济增长率的影响。并由此导出了一个计算灾害间接经济损失的方法，为从宏观的角度分析灾害损失与经济增长的关系提供了一种思路。     

地震灾害产业关联间接经济损失评估

地震灾害破坏了一个城市或地区的经济体系的均衡运行状态,震后“残余”的生产能力资源必须经过一段时间的重新调整,才能达到某一新的、较低程度的均衡水平。本文利用投入产出分析法,从机会成本的观点,对调整阶段的生产能力资源“呆滞”损失即产业关联损失进行了评估。     

Risk of amniocentesis in women screened positive for Down syndrome with second trimester maternal serum markers

In routine obstetrical practice, prior to offering invasive prenatal diagnosis, it is crucial to weigh the risks attendant on amniocentesis against the individual's risk of aneuploidy. We took advantage of a policy of follow-up of patients undergoing Down syndrome maternal serum screening to compare the rates of fetal loss before 24 weeks and of early premature delivery at 24–28 weeks between women who underwent amniocentesis and women who did not. A total of 54 902 patients entered the study, of whom 4039 (7.35%) were lost to follow-up and 387 were excluded because of a severe fetal abnormality. Of the 50 476 remaining patients, 3472 had an amniocentesis whereas 47 004 had not and served as controls. In the amniocentesis group, the fetal loss rate before 24 weeks was 1.12% (95% CI=1.08–1.15) and the 24–28 weeks premature delivery rate was 0.40% (95% CI=0.39–0.41) which was significantly higher than in controls (0.42% with 95% CI 0.41–0.43 and 0.24% with 95% CI 0.23–0.25, respectively). The 0.86% difference in adverse outcome rates between the amniocentesis and control groups may be attributable to amniocentesis and compares favourably with the positive predictive value of maternal serum markers (1.70%) observed in the present study. Copyright © 2002 John Wiley & Sons, Ltd.     

Groundwaters at Risk: Wetland Loss Changes Sources,Lengthens Pathways,and Decelerates Rejuvenation of Groundwater Resources

Wetland loss alters the hydrology of wetlandscapes in poorly understood ways. To quantify the effects of wetland loss on subsurface hydrology, a physically based hydrologic model that simulates the timing and pathways of subsurface hydrologic connections was coupled with wetland inventories over a 50‐year period during which substantial wetland loss occurred. The model revealed, based on vertical variations in saturated hydraulic conductivities, wetland loss of different degrees led to a contraction of catchment contributing areas to local surface waters but an expansion of contributing areas to the regional surface water body. This shift in groundwater contributing areas reflected (1) a decrease in baseflow contribution to the local surface water bodies, and (2) an increase in the transit time and length of subsurface hydrologic connections with an associated increase in the magnitude and age of baseflow discharging to the regional surface water body. The model also showed regions with thick permeable aquifers were particularly sensitive to the loss of wetlands. Our ability to predict these changes in hydrology of the watershed provides important support for designing science‐based policies to promote sustainable water resource management.     

邻避设施导致的资产损失评估研究——以南京市为例

随着居民环境和公众维权意识的提高,邻避冲突会逐步从感性的情绪表达过渡到理性的利益诉求。选择房地产作为度量邻避设施导致的资产损失的媒介,基于双重差分模型构建了邻避设施导致的资产损失评估方法。以南京市为例,选择55个有效住宅社区1980个样本作为处理组,选择25个商圈住宅社区900个样本作为对照组,研究了化工厂、污水处理厂、公墓和监狱四种典型邻避设施对周边资产价格的影响。研究发现:不同邻避设施对周边资产影响不同;化工厂、监狱、公墓和污水处理厂的影响程度依次为302、284、194和180;区域繁华因素等可以消除邻避设施的部分影响;邻避设施周边资产的市场表现仅满足"上涨时涨得少",而不满足"下跌时跌得多"的特点。     

基于径向线损的DG对配电网安全的影响研究

分布式电源并网对配电网有很大影响,包括电压水平、故障水平、线损、安全性、网络可靠性等方面,且其影响程度与分布式电源的容量和安装位置密切相关。本文基于径向式配电网、分布式电源的功率模型和恒功率静态负荷模型,分析和评估当两个等效的分布式电源系统同时并入简单径向配电网时,配电网线损的变化情况。文中,通过搭建理想模型,得出量化线损变化率的具体计算公式并对模型结果进行评述和讨论,将对未来提高线路输电效率的研究和保障配电网安全运行发挥重要作用。     

低成本复合材料在小型飞艇吊舱上的应用

目的研究低成本复合材料在小型飞艇吊舱上的工程应用。方法通过材料选型、吊舱结构设计、铺层设计、强度分析和试验试飞等途径。结果实现了低成本复合材料在中小型飞艇吊舱上的应用。结论相比传统铝合金吊舱,复合材料吊舱质量减轻约40%、外形更美观、装配强度降低、成本相当。     

管道消声器测试系统

研制了完全符合ISO7135-2003和GB/T 25516-2010新标准的管道消声器测试系统。为噪声控制、气动声学、声隐身、环境声学研究工作提供科研支撑和保障条件。解决目前国内管道消声器测试系统不标准、测量不确定度偏大,测试结果难以比对的问题。该测试系统可满足较大气流(≤16.5m3/s)、较大尺度消声器的以下测试功能:——有气流和无气流状态下,管道消声器的频带插入损失;——消声器的气流再生噪声的频带声功率级;——有气流通过时,管道消声器的全压损失;——风道末端单元的频带传声损失。