斜拉桥钢混结合部位力学性能分析

钢混结合部位的设计是混合梁斜拉桥设计中最为关键的环节之一,该部分结构构造复杂,材料的差异性使得应力集中现象极易产生,是结构的薄弱部位。根据工程实例简单介绍斜拉桥钢混结合部位的设计要点及传力途径,并采用有限元分析方法对其局部力学性能进行分析,真实反映结合部位混凝土梁和钢箱梁的应力分布情况。     

青岛高新区雨水利用研究

在水资源急缺以及雨水利用技术大规模应用下,对青岛高新区提出了雨水利用的开源模式,并进行雨水利用试点,可促进该区域的水资源持续利用。     

浅谈调蓄池在大定海低标排水系统改造工程中的应用

上海中心城区的合流制强排系统雨天放江,已成为上海城区水体污染的主要原因之一,设置调蓄池可以减少排入黄浦江的污染物总量,减轻对黄浦江的污染。该文介绍了调蓄池在大定海低标排水系统改造工程中的作用、设置形式、调蓄容积计算、运行模式和防沉砂设计。     

乔列斯基分解应用于偏相干问题的可行性研究

在应用传统的偏相干方法进行噪声源识别时,计算条件输入和耦合较为繁琐、复杂。文章首先通过对偏相干和乔列斯基分解的分析,得到两者之间的关系;进一步运用数学归纳法,从理论上证明了乔列斯基分解应用于偏相干问题的可行性;然后指出对归一化互谱矩阵进行乔列斯基分解,可直接得到各源的贡献比大小;最后给出了应用乔列斯基分解解决偏相干问题的一般步骤。舱段试验验证了该方法的可行性和实时性。     

出行者特征要素对公交服务模式的影响分析

公共交通是面向大众的服务,公共交通服务模式的制定与完善需要重点考虑出行者的出行需求,才能从根本上提高公共交通的竞争力。借鉴服务经济学的理论将公共交通服务模式分为公交服务标准、出行者界面、公交服务环境和技术4个维度。基于攀枝花市居民出行调查与公交专项调查数据,应用SPSS定量分析出行者特征要素与公交服务选择的相关性,以考察研究出行者对于公交服务的需求,并提出改善策略。通过研究表明,出行目的、出行时间、职业和年龄与公交服务模式的相关性较大。     

8170型柴油机应用可变几何排气管增压系统的计算研究

为了实现8缸柴油机高低负荷兼顾,提出新的可变几何排气管增压系统,通过安装在排气管上的可控阀门来实现增压方式的转换。对可变几何排气管增压系统进行稳态和瞬态计算研究。稳态计算结果表明,与原机MPC增压系统相比,在25%、50%、75%和100%负荷时,可变几何排气管增压系统的平均扫气系数均大于MPC系统的平均扫气系数,油耗均小于MPC增压系统的油耗。瞬态计算结果表明,可控阀门关闭以后,压气机后进气压力增加的程度较大。     

水下爆炸载荷作用下舰船总体毁伤模式研究

建立舰船三维有限元模型,采用数值仿真方法计算舰船总体在水下爆炸载荷作用下的动响应,讨论船体主要构件破坏模式以及舰船鞭状运动对船体总纵强度的影响,总结舰船总体在冲击波阶段与气泡脉动阶段舰船毁伤模式及规律。     

Competition and disruption in a dynamic urban supply chain

Rapid changes and complexities in business environments have stressed the importance of interactions between partners and competitors, leading supply chains to become the most important element of contemporary business environments. There is a concomitant need for foresight in describing supply chain performance in all operating environments, including those involving punctuated disruptions. Furthermore, the urban metropolis is now widely recognized to be an environment which is especially vulnerable to supply chain disruptions and for which integrated supply chain decisions can produce very substantial net benefits. Accordingly, this paper presents a dynamic supply chain network model formulated as a differential variational inequality; the model is fashioned to allow consideration of supply chain disruption threats to producers, freight carriers, and retail enterprises. The DVI is solved using a fixed-point algorithm, and a simple numerical example, introduced to illustrate how the impacts of supply chain disruptions may be quantified, is presented.     

Approximate network loading and dual-time-scale dynamic user equilibrium

In this paper we present a dual-time-scale formulation of dynamic user equilibrium (DUE) with demand evolution. Our formulation belongs to the problem class that Pang and Stewart (2008) refer to as differential variational inequalities. It combines the within-day time scale for which route and departure time choices fluctuate in continuous time with the day-to-day time scale for which demand evolves in discrete time steps. Our formulation is consistent with the often told story that drivers adjust their travel demands at the end of every day based on their congestion experience during one or more previous days. We show that analysis of the within-day assignment model is tremendously simplified by expressing dynamic user equilibrium as a differential variational inequality. We also show there is a class of day-to-day demand growth models that allow the dual-time-scale formulation to be decomposed by time-stepping to yield a sequence of continuous time, single-day, dynamic user equilibrium problems. To solve the single-day DUE problems arising during time-stepping, it is necessary to repeatedly solve a dynamic network loading problem. We observe that the network loading phase of DUE computation generally constitutes a differential algebraic equation (DAE) system, and we show that the DAE system for network loading based on the link delay model (LDM) of Friesz et al. (1993) may be approximated by a system of ordinary differential equations (ODEs). That system of ODEs, as we demonstrate, may be efficiently solved using traditional numerical methods for such problems. To compute an actual dynamic user equilibrium, we introduce a continuous time fixed-point algorithm and prove its convergence for effective path delay operators that allow a limited type of nonmonotone path delay. We show that our DUE algorithm is compatible with network loading based on the LDM and the cell transmission model (CTM) due to Daganzo (1995). We provide a numerical example based on the much studied Sioux Falls network.     

基于出行方式链的城市轨道交通客流分析方法

传统"四阶段"法预测流程无法准确预测与轨道交通接驳的交通方式及换乘客流.借鉴基于活动的交通需求模型中利用出行链来解释人的出行行为的方法,提出了基于出行方式链的轨道交通客流分析方法.使用三层的Nested-Logit模型来模拟出行者选择轨道交通为主要出行方式接驳其他交通方式和预测各种方式的客流,建立了轨道交通出行方式链模...