水下锚系动基座发射系统动力学数学建模

深入研究了水下动基座发射导弹在海流作用下和发射过程中动力学系统的动力学问题。建立了水下锚系发射导弹动力学系统在海流作用下点火发射过程完整的数学模型。最后的算例表明开盖过程对导弹发射前的初始状态有影响,海流的作用将会引起发射平台发射前初始姿态和位置的改变。     

A robust optimization approach for dynamic traffic signal control with emission considerations

We consider an analytical signal control problem on a signalized network whose traffic flow dynamic is described by the Lighthill–Whitham–Richards (LWR) model (Lighthill and Whitham, 1955; Richards, 1956). This problem explicitly addresses traffic-derived emissions as constraints or objectives. We seek to tackle this problem using a mixed integer mathematical programming approach. Such class of problems, which we call LWR-Emission (LWR-E), has been analyzed before to certain extent. Since mixed integer programs are practically efficient to solve in many cases (Bertsimas et al., 2011b), the mere fact of having integer variables is not the most significant challenge to solving LWR-E problems; rather, it is the presence of the potentially nonlinear and nonconvex emission-related constraints/objectives that render the program computationally expensive.To address this computational challenge, we proposed a novel reformulation of the LWR-E problem as a mixed integer linear program (MILP). This approach relies on the existence of a statistically valid macroscopic relationship between the aggregate emission rate and the vehicle occupancy on the same link. This relationship is approximated with certain functional forms and the associated uncertainties are handled explicitly using robust optimization (RO) techniques. The RO allows emissions-related constraints and/or objectives to be reformulated as linear forms under mild conditions. To further reduce the computational cost, we employ a link-based LWR model to describe traffic dynamics with the benefit of fewer (integer) variables and less potential traffic holding. The proposed MILP explicitly captures vehicle spillback, avoids traffic holding, and simultaneously minimizes travel delay and addresses emission-related concerns.     

Accounting for traffic speed dynamics when calculating COPERT and PHEM pollutant emissions at the urban scale

Coupling a traffic microsimulation with an emission model is a means of assessing fuel consumptions and pollutant emissions at the urban scale. Dealing with congested states requires the efficient capture of traffic dynamics and their conditioning for the emission model. Two emission models are investigated here: COPERT IV and PHEM v11. Emission calculations were performed at road segments over 6 min periods for an area of Paris covering 3 km². The resulting network fuel consumption (FC) and nitrogen oxide (NOx) emissions are then compared. This article investigates: (i) the sensitivity of COPERT to the mean speed definition, and (ii) how COPERT emission functions can be adapted to cope with vehicle dynamics related to congestion. In addition, emissions are evaluated using detailed traffic output (vehicle trajectories) paired with the instantaneous emission model, PHEM.COPERT emissions are very sensitive to mean speed definition. Using a degraded speed definition leads to an underestimation ranging from −13% to −25% for fuel consumption during congested periods (from −17% to −36% respectively for NOx emissions). Including speed distribution with COPERT leads to higher emissions, especially under congested conditions (+13% for FC and +16% for NOx). Finally, both these implementations are compared to the instantaneous modeling chain results. Performance indicators are introduced to quantify the sensitivity of the coupling to traffic dynamics. Using speed distributions, performance indicators are more or less doubled compared to traditional implementation, but remain lower than when relying on trajectories paired with the PHEM emission model.     

Modal analysis of real-time,real world vehicular exhaust emissions under heterogeneous traffic conditions

This study presents the characteristics of real world, real time, on-road vehicular exhaust emission namely, carbon monoxide (CO), nitric oxide (NO), hydrocarbons (HC), and carbon dioxide (CO₂) emitted under heterogeneous traffic conditions. Field experiments were performed on major category of vehicles in developing countries, i.e. two-wheelers, auto-rickshaws, cars and buses. The on-board monitoring was carried out on different corridors with varying road geometry. Results revealed that the driving cycle was dependent on the road geometry, with two lane mixed flow corridor having lot of short term events compared to that of arterial road. Vehicular emissions during idling and cruising were generally low compared to emissions during acceleration. It was also found that emissions were significantly dependent on short term events such as rapid acceleration and braking during a trip. Also, the standard emission models like COPERT and CMEM under predicted the real world emissions by 30–200% depending upon different driving modes. The on-road emissions measurements were able to capture the emission characteristics during the micro events of real world driving scenarios which were not represented by standard vehicle emission measured at laboratory conditions.     

Urban roadside monitoring and prediction of CO,NO2 and SO2 dispersion from on-road vehicles in megacity Delhi

The study inspects the traffic-induced gaseous emission dispersion characteristics from the urban roadside sites in Delhi, India. The concentration of pollutants viz. CO, NO₂ and SO₂ along with traffic and ambient atmospheric conditions at five selected local urban road sites were simultaneously measured. A developed General Finite Line Source Model (GFLSM) was used to predict the local roadside CO, NO₂ and SO₂ concentrations. A comparison of the observed and predicted values emission parameters using GFLS model has shown that the predicted values for SO₂, CO and NO₂ at all the selected local urban roadside locations are found to lie within the error bands of 5%, 6%, and 7% respectively. A high level of agreement was found between the monitored and estimated CO, NO₂ and SO₂ concentration data. From the study, it has also been established that the developed model exhibits the capability of reasonably predicting the characteristics of gaseous pollutants dispersion from on-road vehicles for the urban city air quality.     

基于模块化软件的船用乏汽冷却监控系统研制

为提高冷却船舶蒸汽动力装置在运行过程中产生乏汽的速度,设计一套基于模块化程序库和数据库软件的乏汽冷却监控系统,并搭建陆上试验平台进行试验验证。试验结果表明:该系统工作稳定,性能优良,特别是在液位控制和温度控制2项核心指标上表现优异,能达到预期的设计目标,具有广阔的应用前景。     

集卡调度方式对集装箱港区碳排放的影响

集卡已成为集装箱港区内的主要碳排放源,尤其两艘大型集装箱船舶同时作业时,港区内集卡碳排放问题严重。针对该情况下集卡调度模式的特征,基于智能体仿真技术构建集装箱码头生产作业微观仿真模型,定量分析传统先卸后装、双船一装一卸、同贝同步装卸工艺下集卡调度方式与集卡配置数量对船舶在港时间、集卡碳排放量的影响。实例表明,采用同贝同步装卸作业方案可保证装卸效率,并有效减少集卡碳排放,而集卡配置数量只对集卡怠速行驶产生的碳排产生影响。     

基于喷水降温冷却的舷侧排气系统声学性能分析

对于船舶动力装置喷水冷却式舷侧排气系统,喷水降温装置的开启会使系统内温度发生剧烈变化,因此排气系统内烟气属性会发生改变,进而影响舷侧排气消声系统的性能。文章首先通过Fluent获得喷淋冷却前后舷侧排气系统的流体动力学计算结果,改变冷却水流量后又得到消声系统在不同喷水流量下的温度场;再将CFD计算结果作为求解排气系统传递损失的计算输入,得到了冷却水喷淋前后舷侧排气系统的声学性能,从而获得喷水降温冷却可以提高整个系统在低频段的消声性能的结论。该结果可为今后舷侧排气系统紧凑化设计提供参考。     

西秦岭隧道TBM施工节能减排措施应用研讨

兰渝铁路西秦岭隧道是目前中国铁路建筑史上TBM掘进最长的隧道,工期紧,能源、资源投入大。项目根据TBM工法的实际特点,进一步夯实管理体制基础,紧绕"四节一环保"开展系列措施,同时依托科技创新,突出技术节能措施,并提出节能减排建议,在实现"高产低耗"方面取得了显著成效。