支持协同设计的船舶设计过程模型研究

船舶设计过程模型是在网络环境下开展船舶并行和协同设计系统的基础.本文根据船舶设计的特点,提出了将船舶设计过程按照项目、设计任务和设计活动三个层次进行分解的方法,并给出了船舶设计过程模型形式化定义.该模型明确了设计任务间的并行、顺序和协同关系,可以直接按设计任务构成活动网络图进行规划、分析、管理等工作,使设计过程具有良好的可变更性和可控性.     

固定化高效微生物滤池法处理焦化废水试验研究

采用固定化高效微生物滤池法处理钢铁焦化废水,试验确定了该工艺运行的最佳条件。试验运行工况在：流量为4～6.0 m^3/h、生化处理停留时间25～50h,其中厌氧13～22 h,好氧20～28 h、曝气量40∶1时,处理效果最佳,系统对CODcr的平均去除率达到95.4%、对氨氮平均去除率达到96.1%、对氰化物平均去除率达到99.1%。结果表明,焦化废水经该工艺处理后,满足GB8978—1996二级标准排放要求。     

Time windows in workers' activity patterns: Empirical evidence from the Netherlands

This paper assumes that activities at the home and work location are important determinants of individuals' paths through time and space. Fixed activities at these locations determine to a large extent the duration and timing of time windows – blocks of time available for participation in travel and out-of-home non-work activities. Taking the time spent at home and at the workplace as a starting point, this paper classifies activity patterns on workdays into six groups with distinct home- and work-stay patterns. For this, data are used from the 1998 Netherlands National Travel Survey. The six clusters vary in terms of the duration and timing of time windows and some of the differences can be explained by commute characteristics, types of non-work activities performed, workers' sociodemographic attributes, and their spatiotemporal environment. However, the impact of sociodemographic and spatiotemporal variables on cluster membership is shown to be weak.     

An Exploration of the Relationship between Timing and Duration of Maintenance Activities

The timing and duration of an activity episode are two important temporal aspects of activity-travel behavior. Understanding the causal relationship between these two variables would be useful in the development of activity-based travel demand modeling systems. This paper investigates the relationship between these two variables by considering two different causal structures – one structure in which time-of-day choice is determined first and influences duration and a second structure in which activity duration is determined first and affects time-of-day choice. These two structures are estimated within a discrete-continuous simultaneous equations framework employing a full-information maximum likelihood methodology that allows error covariance. The estimation is performed separately for commuter and non-commuter samples drawn from a 1996 household travel survey data set from the Tampa Bay area in Florida. The results of the model estimation effort show that the causal structure in which activity duration precedes or affects activity timing (time of day choice) performs better for the non-commuter sample. For the commuter sample, the findings were less conclusive with both causal structures offering equally good statistical measures of fit. In addition, for the commuter sample, all error correlations were found to be zero. These two findings suggest that time of day choice and activity episode duration are only loosely related for the commuter sample, possibly due to the relatively non-discretionary and inflexible work activity and travel.     

Residential built environment and walking activity: Empirical evidence of Jane Jacobs’ urban vitality

This study intends to empirically verify Jacobs’ urban vitality theory, which was based on the observations of her New York City neighborhood in the mid-20th century. To examine the relationship between the residential built environment and walking activity, we used telephone survey data consisting of 1823 valid samples from across Seoul, a city characterized by a high population density and a well-established public transportation system. Respondents were asked questions about their residential location, their demographic and socioeconomic characteristics, and their walking activities. This study then used geographic information systems to measure objective indicators of built environment variables within 500-meter buffer areas based on the home addresses of the respondents. Then, this study constructed multilevel regression models with walking activity as the dependent variable. Our results indicated that walking activity is associated with Jacobs’ six conditions for urban vitality, including land use mix, density, block size, building age, accessibility, and border vacuums.     

柴油发动机掺烧生物柴油的经济性研究

为了更好地评价柴油机燃用生物柴油的经济性,分析了生物柴油和0#石化柴油的理化性质,分别对生物柴油的体积分数为0.2,0.5,1的B20、B50、B100 3种燃料和0#柴油在495Q3柴油机上进行了试验。试验结果显示燃用3种燃料的燃油消耗率比0#柴油在中小负荷时平均增加5.30%,9.65%,19.04%,大负荷时平均增加2.86%,4.75%,9.64%;能量等值折合油耗率在中小负荷时平均增加2.65%,2.63%,5.74%,大负荷时平均降低0.26%,1.97%,4.80%。     

二灰冷再生沥青路面基层路用性能研究

通过对原路材料进行材料组成分析,并且通过对几种不同配合比的冷再生材料的无侧限抗压强度、劈裂强度、冲刷性能的初步研究,对二灰冷再生材料的性能做出了初步评价.二灰冷再生材料基本可以满足规范对沥青路面的半刚性基层的要求.     

As2O3诱导人卵巢癌细胞株HO8910凋亡和端粒酶活性的关系

目的探讨As2O3诱导HO8910细胞凋亡和端粒酶活性变化的关系。方法用不同浓度的As2O3溶液作用卵巢癌细胞株HO8910,于不同时间点收集细胞,MTT法检测细胞生长抑制率;FCM检测细胞凋亡率;TRAP-银染法观察端粒酶活性的变化。结果As2O3溶液对HO8910有生长抑制和诱导凋亡的作用,与药物浓度和作用时间相关。不同浓度As2O3作用HO8910细胞,其端粒酶活性在24h无明显改变,随着作用时间的延长,端粒酶活性逐渐下降,随着药物浓度的升高端粒酶活性也呈不断下降趋势,以致消失。结论As2O3可以诱导卵巢癌细胞株HO8910发生凋亡,其机制可能不是通过端粒酶活性下降直接调控的,但端粒酶调控与凋亡调控有一定相关性。     

动脉粥样硬化发病的炎症机制的研究进展

动脉粥样硬化是临床常见疾病,是缺血性心脑血管病的主要病理基础。迄今为止,其发病机制尚未完全清楚,因而临床尚无有效而特异性的药物治疗。大量基础和临床研究表明,动脉粥样硬化是一种慢性炎症性疾病,是血管壁对各种损伤的一种异常反应,具有经典炎症变性、渗出及增生的特点。炎症反应贯穿动脉粥样硬化发病的各个阶段,可能是多种致动脉粥样硬化因素致病机制的共同环节或通路。炎症机制不但与动脉粥样硬化的发生发展有关,而且与动脉粥样硬化的多种并发症的发生密切相关。动脉粥样硬化的炎症类型包括生物性炎症、免疫性炎症和化学性炎症。动脉粥样硬化发病初期主要表现为急性渗出性炎症,而在进展期主要表现出慢性增生性炎症的特点。炎症反应中涉及多种炎症细胞、炎性细胞因子、炎性介质、黏附分子、趋化因子、生长因子等。现已证明,多种抗动脉粥样硬化药物具有抗炎作用,抗炎治疗已成为防治动脉粥样硬化的一种新途径。     

牛仔布水洗废水的处理及回用

该文介绍了采用混凝沉淀+生物接触氧化法处理牛仔布水洗废水的处理工艺以及经过深度处理后回用于生产用水的方法,并对其进行了经济分析。