基于DDAM的中间轴承甩油盘抗冲击性能分析

  目的   基座结构作为连接潜艇设备与舰体结构的重要构件,其抗冲击性能对于舰艇生命力具有重要影响。使用等效静力载荷进行基座—设备抗冲击考核流程简便、计算效率较高,但其仅在低阶响应为主要破坏模式时精度较高。  方法   为此,以空气瓶—基座结构为分析对象,研究基座结构低阶模态质量占比不同时,等效静载荷考核与DDAM设计谱考核方式之间结构应力的相对误差,对比2种考核方式的应力分布关系,明确静G法抗冲击考核计算的具体适用范围。以潜艇结构实际冲击环境为输入载荷,对比分析动力学设计分析方法（DDAM）设计谱抗冲击考核计算结果与时间历程法考核结果的相对误差。  结果   结果显示,当舰艇设备结构的单阶模态质量占比较大时,使用静G法相较于DDAM谱分析方法具有较高的精度。对于安装于潜艇甲板部位的设备,GJB 1060抗冲击标准中规定的冲击载荷可基本等效为冲击因子0.7工况下且爆源均与基座结构在潜艇同一横截面上时的结构冲击环境。  结论   研究结果可为舰载设备抗冲击考核方法的选择提供一定的参考价值。     

关于人员承受爆炸冲击与振动耐受限标准划分的探讨

  目的  为有效保护水面舰船舰员免受水下非接触爆炸所引起的冲击损伤,  方法  在分析水面舰船人员冲击环境和安全限值的基础上,提出舰员抗冲击防护地板设计方法,设计一种具有非线性变刚度力学特性的新型抗冲击弹性地板。在模拟舰船典型中、重度冲击环境的冲击台试验中,对抗冲击弹性地板的防护效果进行验证和评估。  结果  结果表明,抗冲击弹性地板可以衰减88%以上的冲击载荷,能有效降低对舰员的冲击损伤程度。  结论  所做研究可为舰船冲击环境恶劣的部位提供有效的舰员抗冲击防护。     

科学认识与合理利用海洋环境

针对海洋环境状况以及面临的主要问题,在充分认识按照科学发展观的要求开发利用海洋环境的基础上,提出合理利用海洋环境的思路和自觉保护海洋环境的措施,对促进经济社会的可持续发展具有重要的意义．     

吸收法分离CO2的吸收液试验研究

在小型试验装置上,利用模拟烟气针对不同浓度下MEA（一乙醇胺）、iDEA（甲基二乙醇胺））和脚（氨基乙酸钾）吸收剂的水溶液进行分离CO2试验,考察了三种吸收液对CO2吸收和解吸能力。试验结果表明：三种吸收液在吸收CO2时,其碳化度都随时间的增加而上升,MEA和AAAP吸收液的吸收能力要远远好于MDEA吸收液;对于三种吸收液的解吸,MDEA吸收液在较短的时间内,其解吸就达到了一个稳定状态,表现出良好的解吸效果,而MgA和脚吸收液解吸所需时间较长,解吸效果弱于MDEA吸收液。     

舰船环境下射频对电爆装置的危害

电爆装置作为舰载武器系统中最为敏感的元器件,可能因吸取周围环境的射频能而产生误动作,进而对舰船的战场生存能力构成威胁.为把握其耦合方式和特性,对舰船复杂的射频环境进行了综合分析,同时阐述了电爆装置的射频耦合致损机理.根据天线理论和基于保守估计的两个基本假设,在多个场源同时作用时,对舰船环境的射频能对电爆装置的危害进行了分析与理论计算,结果表明,舰船环境下的射频能可以对电爆装置产生严重的危害.     

The relationship between segment-level built environment attributes and pedestrian activity around Bogota’s BRT stations

Few studies have examined the relationship between micro-scale features of the built environment and street segment usage. Micro-scale features of the built environment include the width of the sidewalk, the presence of amenities such as benches and trash bins, and the presence of crossing aids such as stoplights and crosswalks. This study employs segment-level primary data collected for 338 street segments in close proximity to one of 71 bus rapid transit stations in Bogotá, Colombia. We also use secondary data to control for area-level characteristics such as density, socio-economic stratum, unemployment, and crime. Factor and regression analyses are to use identify two dimensions of the built environment that are associated with higher levels of pedestrian activity: pedestrian-friendly amenities, comprised of wider and higher quality sidewalks and the presence of amenities such as benches, garbage cans, and bike paths; and connectivity, comprised of higher levels of road density, three- and four-way intersections, and density. In addition, we find greater pedestrian activity on segments with higher development intensity, with more mix of land uses, and with more crossing aids. Although the relationships identified are not causal, they are suggestive in terms of planning successful built environment interventions.     

国外海上浮动核电站的产业发展现状

  目的  浮动堆经过在军用舰船上几十年的发展和运行经验积累,反应堆的安全性得到了很大提高,在民用领域的推广应用逐渐被认可,目前亟需解决反应堆装船的适配性问题。安全壳是浮动堆与船体结合的接口,是反应堆装船的船体舱室,其设计不仅要适应船舶的海洋环境条件,还要满足反应堆运行的核安全要求。  方法  首先,从浮动堆安全壳的适应性要求出发,分析安全壳压力与船舶主尺度和重量之间的主要矛盾关系,提出一种浮动堆安全壳分析设计流程。然后,参考陆上核电站和核动力舰船安全壳的特点,以及国外核动力船舶和民用核设施设计规范要求,从安全壳构型与压力控制维度的角度出发,提出一种方形双层抑压安全壳方案。  结果  对安全壳压力特性以及结构强度的分析显示,在设计基准事故工况下,安全壳结构安全,重量和空间指标可控,安全壳的船堆适配性较好。  结论  参考工程经验表明,基于该方案的浮动堆总体指标较好,可为工程人员设计提供参考。     

Multi-agent simulation of individual mobility behavior in carpooling

Carpooling is an emerging alternative transportation mode that is eco-friendly and sustainable as it enables commuters to save time, travel resource, reduce emission and traffic congestion. The procedure of carpooling consists of a number of steps namely; (i) create a motive to carpool, (ii) communicate this motive with other agents, (iii) negotiate a plan with the interested agents, (iv) execute the agreed plans, and (v) provide a feedback to all concerned agents. In this paper, we present a conceptual design of an agent-based model (ABM) for the carpooling a that serves as a proof of concept. Our model for the carpooling application is a computational model that is used for simulating the interactions of autonomous agents and to analyze the effects of change in factors related to the infrastructure, behavior and cost. In our carpooling application, we use agent profiles and social networks to initiate our agent communication model and then employ a route matching algorithm, and a utility function to trigger the negotiation process between agents. We developed a prototype of our agent-based carpooling application based on the work presented in this paper and carried out a validation study of our results with real data collected in Flanders, Belgium.     

Effect of built environment measures on trip distance and mode choice decision of non-workers from a city of a developing country,India

This paper investigates the influence of built environment measures on trip distance and walking decision of non-workers by segmenting the populace based on trip purpose, vehicle ownership, and the presence of school-going children in households. The built environment measures of home zone of individuals considered for the present analysis include zonal population density, zonal school enrolment, land use mix diversity index, and an indicator variable that captures if neighbourhoods have footpaths of adequate width available. Statistical analyses conducted on home-based trips indicate that an increase in the land use diversity of a zone has its strongest negative effect on distance travelled for participating in personal/household business activities. The non-vehicle owning group exhibit a higher tendency to walk than the vehicle-owning group for an increase in the land use diversity of zones. Further, the study suggests that school-enrolment in a zone also influences the travel decisions of non-workers in families with school-going children.     

Development of destination choice models for pedestrian travel

Most research on walking behavior has focused on mode choice or walk trip frequency. In contrast, this study is one of the first to analyze and model the destination choice behaviors of pedestrians within an entire region. Using about 4500 walk trips from a 2011 household travel survey in the Portland, Oregon, region, we estimated multinomial logit pedestrian destination choice models for six trip purposes. Independent variables included terms for impedance (walk trip distance), size (employment by type, households), supportive pedestrian environments (parks, a pedestrian index of the environment variable called PIE), barriers to walking (terrain, industrial-type employment), and traveler characteristics. Unique to this study was the use of small-scale destination zone alternatives. Distance was a significant deterrent to pedestrian destination choice, and people in carless or childless households were less sensitive to distance for some purposes. Employment (especially retail) was a strong attractor: doubling the number of jobs nearly doubled the odds of choosing a destination for home-based shopping walk trips. More attractive pedestrian environments were also positively associated with pedestrian destination choice after controlling for other factors. These results shed light on determinants of pedestrian destination choice behaviors, and sensitivities in the models highlight potential policy-levers to increase walking activity. In addition, the destination choice models can be applied in practice within existing regional travel demand models or as pedestrian planning tools to evaluate land use and transportation policy and investment scenarios.