基于PEMS测量的机动车尾气预测研究

为了实现对机动车尾气排放的控制,解决现有预测模型未能通过燃油消耗来研究污染物排放以及未能建立起油耗及其车外可观测影响因素之间的关系问题,对油耗数据及其理论模型进行了研究,提出了微观综合预测模型,它是根据便携式尾气测量系统(PEMS)实际工况下测量的机动车油耗与各污染物排放数据,并结合油耗的理论模型建立起的综合预测模型;最后,通过实验对综合预测模型进行了实例分析与验证;实验结果表明,综合预测模型首次对污染物CO和NO的预测模拟值和实测值之间的平均误差分别为14.3%和12.8%,实现了较好的预测效果,为进一步研究燃油消耗和排放的关系奠定了很好的基础。     

RWA方法对WDM网络P圈优化性能的影响

研究不同的路由和波长分配（RWA）方法对无波长变换WDM网络P圈优化性能的影响.提出了用负载均衡的方法对各波长层的工作容量进行均衡,以降低网络总容量.分别研究了动态分层通用RWA（DL-GRWA）、最短路径RWA（SP-RWA）、动态分层负载均衡（DL-LB）、最短路径负载均衡（SP-LB）、固定波长负载均衡（FW-LB）5种方法对网络总容量的影响.仿真发现,无论何种RWA方法,随着圈最大跳数限制的变大,网络总容量都逐渐降低,其中SP-LB方法所需要的网络总容量最小.     

车载自组织网络中基于蚁群算法的簇路由协议

由于车辆的高速移动及拓扑动态变化,构建稳定的传输路径是车载自组织网络VANETs(Vehicular ad hoc Networks)应用的关键。而簇技术建立稳定传输路径的有效技术之一。为此,提出基于蚁群算法的簇路由ACCR(Ant Colony algorithm based cluster routing)协议。蚁群系统是典型的启发性算法,能够解决簇划分问题。据此,ACCR协议利用蚁群算法选择簇头,提高簇的稳定性和数据传输性能。仿真结果表明,与ACO-CR协议相比,提出的ACCR协议的簇头寿命提高了近20%,数据传输率提高了近45%。     

AUV双基地合成孔径声呐成像实验*

单基地合成孔径声呐成像通常基于点目标假设,其相干积累处理不能克服分布型目标散射模式的起伏效应。收发异置的双基地声呐可以从不同角度观察目标,充分挖掘目标散射模式的角度依赖特性,在对水下目标(尤其人造目标)检测与定位方面,相对仅仅观测后向散射的单基地声呐有潜在的优势。该文 介绍一种基于自主水下航行器的双基地合成孔径声呐系统,重点介绍湖试成像的结果,验证双基地合成孔径声呐的可行性。同时通过引入目标散射模式建模的宽角度合成孔径声呐处理,实现了对目标探测性能的提升。     

A Petrov－Galerkin Method Based on Symmetrization for Parabolic Convection－Diffusion Problems

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New lower bounds for the Symmetric Travelling Salesman Problem

In this paper new lower bounds for the Symmetric Travelling Salesman Problem are proposed and combined in additive bounding procedures. Efficient implementations of the algorithms are given; in particular, fast procedures for computing the linear programming reduced costs of the Shortest Spanning Tree (SST) Problem and for finding all ther-SST of a given graph, are presented. Computational results on randomly generated test problems are reported.     

Pressure and time treatment for Chebyshev spectral solution of a Stokes problem

To investigate the influences of time scheme, pressure treatment and initial conditions in incompressible fluid dynamics, a Stokes problem is solved numerically on a slab geometry within the framework of spectral approximation in space. Four algorithms are examined: splitting schemes, influence matrix method, penalty formulation and pseudo-spectral space-time technique. It is shown that splitting schemes are less accurate than the other processes. Furthermore, the initial field should respect a compatibility condition to avoid singularities at the initial time. If it is not possible to build such a compatible field, the numerical procedure has to present good damping properties at the first steps of the time integration.     

Collision avoidance strategies and coordinated control of passenger vehicles

Recent research has demonstrated the efficaciousness of the coordinated control of platoons of vehicles in order to homogenize the traffic flows and improve the exploitation of the capacity of road networks. Yet, taking into account the necessity of reducing, in the next years, the number of accidents involving pedestrians or other vulnerable road users (VRUs), like cyclists and motorcyclists, it seems useful to provide the control systems of the vehicles of the platoon with some collision detection and avoidance capability. This issue is investigated in this paper. The control system presented in this paper allows to maintain cruise conditions, and, as a novelty with respect to consolidated proposals, to avoid the collision with possible VRUs present on the road. The proposed control system is realized by means of vehicle supervisors, which, on the basis of the data acquired by the sensors, make the decision on which is the appropriate current control mode for each controlled vehicle, and manage the switches among low-level controllers. These are designed relying on a simple bicycle model, and according to a sliding mode control methodology. This choice is motivated by the robustness features of the sliding mode design, which appears particularly appropriate dealing with the automotive context.     

Next-generation NATO reference mobility model complex terramechanics – Part 1: Definition and literature review

The US army along with NATO member and partner nations’ militaries need an accurate software tool for predicting ground vehicle mobility (such as speed-made-good and fuel-consumption) on world-wide terrains where military vehicles may be required to operate. Currently, the NATO Reference Mobility Model (NRMM) is the only NATO recognized tool for assessing ground vehicle mobility. NRMM was developed from the 1960s to the 1980s and relies on steady-state empirical formulas which may not be accurate for new military ground vehicles. A NATO research task group (RTG-248) was established from 2016 to 2018 to develop the NG-NRMM (next-generation NRMM) software tool requirements and an NG-NRMM prototype which uses high-fidelity “simple” or “complex” terramechanics models for the terrain/soil along with modern 3D multibody dynamics software tools for modeling the vehicle. NG-NRMM Complex Terramechanics (CT) models are those that utilize full 3D soil models capable of predicting the 3D soil reaction forces on the vehicle surfaces (including tires, tracks, legs, and under body) and the 3D flow and deformation of the soil including both elastic and plastic deformation under any 3D loading condition. In Part 1 of this paper, an overview of the full spectrum of terramechanics models from the highest fidelity to the lowest fidelity is presented along with a literature review of CT ground vehicle mobility models.