内流式锥阀流场的数值模拟与结构优化

锥阀具有密封性能好、过流能力强、响应快、抗污染能力强等特点,在流体输送中得到了广泛的应用。应用PHOENICS流体计算软件及k-ε湍流计算模型,对内流式锥阀的内部流场进行了模拟仿真,研究了流量变化、开度变化对锥阀流场特性的影响。研究结果对分析锥阀的性能、进行流道的结构优化和实际工程应用都具有一定的指导作用。     

分段扫砂模式在造船厂的推广应用

为了满足环保对造船厂VOCs排放总量的限制,并实现降低涂装制造成本降低之目的,如何减少油漆使用总量成为了一条关键探索路径.扫砂作业模式的推广正是打通这一路径的最有效方式之一.通过对分段扫砂与冲砂作业模式的深入对比研究,总结出扫砂作业模式所特有的经济效益,并提供了一套建立扫砂作业基准的基本程序.     

油水分离器技术及设计

机舱设置油水分离装置和油分浓度监视器是国际防污公约规定之一,综合本人在船工作经历,设计一套实用性较强、准确性较高的带反冲洗的真空式油水分离器,它采用双电极自动排油控制、激光油分浓度监视器,满足油水分离的要求。     

电动汽车用锂离子电池单体温度场分析

文章通过实验测得了锂离子电池内阻在常温下随soc的变化情况.实验显示放电时soc在0.2到1之间时内阻变化不大,soc小于0.2时内阻急剧升高,且充电内阻明显大于放电内阻.之后进行了锂离子电池单体在常温下,0.8C和1C的充放电温升试验.获得了温升随时间变化的数据.并通过fluent对电池单体进行了与实验对应的仿真,仿...     

华蓥山隧道排水的生态环境问题及效应

基于两次现场咨询工作经历及收集的资料,探讨了华蓥山隧道排水造成地下水资源流失,煤系质水入侵及水文徨环失衡等生态环境问题及形成机理,以及同此带来的岩溶入泉枯竭,地下水水质恶化,地表水体污染,地表水土流失等一系列负效应,分析结果表明,隧道长期排水将形成较大规模的降位漏斗,由于该漏斗的扩展,导致在疏干带内较强烈的水文地球化学作用,进而威胁隧道衬砌的稳定性。     

寒区老旧铁路隧道改造方案研究

近年来,随着环境污染问题及能源短缺问题的日益突出,结合运量增长需要,我国老旧铁路电气化改造工程日益增多。受净空条件限制,隧道工程往往成为电气化改造工程中控制节点,是土建工程改造的重点和难点。改建方案的合理性对整个工程的施工风险和工程投资有着重大的影响。长图线长春至吉林段共有3座既有隧道,分别修建于1912年,1978年和2002年,修建时间跨度大,隧道限界、材料标准及施工工艺相差迥异,衬砌缺陷及病害较为典型,在我国东北严寒地区老旧隧道中具有一定的代表性。以长图线电气化改造工程为例,通过对工程改造方案的研究和比选,提出严寒地区老旧铁路隧道电气化改造设计的原则及方法。     

An analytical model to conduct a person-based evaluation of transit preferential treatments on signalized arterials

The complexities of urban transportation networks where multiple modes with different characteristics and needs travel in combination with constraints on space and funding make the sustainable management of these systems a challenge. In order to improve transit service, space (e.g., dedicated bus lanes) and time (e.g., transit signal priority strategies) Transit Preferential Treatments (TPT) are deployed to improve transit operations. The objective of this paper is to develop an analytical model that allows for a person-based evaluation of alternative TPTs when considered individually and in combination. In particular, the analytical model is developed to assess person delay and person discharge flow at any intersection that is part of a signalized arterial, where auto arrivals are in platoons. The performance of TPTs is evaluated using both the analytical model and through microsimulation tests on two intersections of San Pablo Avenue in Berkeley, CA. Space TPTs such as dedicated bus lanes and queue jumper lanes are beneficial in reducing bus person delay when provided in addition to the existing lanes; however, the effectiveness of time TPTs such as green extension depends on the level of auto demand in combination with signal settings. Changes in person discharge flow are not significant for any of the treatments tested with the exception of the bus lane substitution with and without green extension, which led to a significant decrease in person discharge flow. Increased bus frequency increases the effectiveness of transit signal priority in reducing total and bus person delay. The analytical model results produce ranking outcomes that are comparable with the microsimulation ones and therefore, the model may be used for a quantitative evaluation of TPTs without the need for data intensive and time consuming calibration efforts required for microsimulation models. The developed model can be used to guide infrastructure and investment decisions on where such TPTs should be implemented and under what conditions space TPTs should be combined with time TPTs to improve person mobility.     

铁路隧道凸壳型防排水板通水能力研究

文章基于我国铁路隧道防排水体系的技术现状及铁路隧道防排水领域存在的主要问题,介绍了凸壳型防排水板的基本特征,并对凸壳型防排水板的等效管径、通水量等进行了理论计算和研究。结果表明:单位幅宽(隧道纵向延长米)凸壳型防排水板的最小等效管径为0.0626 m,不同工况下其通水量为376~2138 m^3/d;凸壳型防排水板的通水能力是环向盲管的18~38倍;提高凸壳型防排水板凸壳体的抗压强度是确保其通水能力的有效措施;凸壳型防排水板可全面替代传统的防水板与环向排水盲管设置。     

三峡水库常年回水区和尚滩汛期航道条件变化分析*

收集三峡水库常年回水区洪水急流滩——和尚滩大量的实测地形、水文及过往船舶航行资料,建立了数学模型,分析汛期的航道条件变化,并得到和尚滩的船舶自航上滩临界流量条件。结果表明：175 m试验性蓄水后,和尚滩航道条件有所改善,流速、比降减缓,水深、航宽增加,万吨级船队及3 000吨船舶自航上滩临界流量有所提升,航运效益明显提高。     

船舶污水排放面临的问题及解决措施

主要介绍了船舶污水的种类及其所含污染物,船舶排放的污水对水体及人类健康造成的危害.通过国内外各地方污水排放指标与国际防污公约的对比,指出船舶污水排放面临的挑战,提出船舶适应各种污水排放要求的技术措施.