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A GIS‐based method to identify cost‐effective routes for rural deviated fixed route transit

Deviated fixed route transit (DFRT) service connecting rural and urban areas is a growing transportation mode in the USA. Little research has been done to develop frameworks for route design. A methodology to explore the most cost‐effective DFRT route is presented in this paper. The inputs include potential DFRT demand distribution and a road network. A heuristic is used to build possible routes by starting at urban cores and extending in all network directions in certain length increments. All the DFRT routes falling in the length range desired by the users are selected. The cost effectiveness of those routes, defined by operating cost per passenger trip, is compared. The most cost‐effective route is selected and presented in a GIS map. A case study illustrates the methodology in several Tennessee metropolitan regions. The most cost‐effective route length is case specific; some routes (e.g. those out of our Nashville case) are most cost effective when short, while others (e.g. those out of Memphis) are most cost effective when long. Government agencies could use the method to identify routes with the lowest operating cost per passenger given a route length or an operating cost budget. Copyright © 2016 John Wiley & Sons, Ltd.     

Dual objective active suspension system based on a novel nonlinear disturbance compensator

This paper proposes an active suspension system to fulfil the dual objective of improving ride comfort while trying to keep the suspension deflection within the limits of the rattle space. The scheme is based on a novel nonlinear disturbance compensator which employs a nonlinear function of the suspension deflection. The scheme is analysed and validated by simulation and experimentation on a laboratory setup. The performance is compared with a passive suspension system for a variety of road profiles.     

Robust inspection technique for detection of flatness defects of oil pans

This paper discusses two different methods for the detection of flatness defects present on the mounting surfaces of oil pans using laser-scanned point clouds. The first method involves registration, which is a widely used method in the field of 3D data inspection: scanned point clouds are registered with CAD data and the iterative closest point (ICP) algorithm is used for further comparison. The second method is our proposed method, a simple yet effective method for measuring the flatness of an oil pan mounting surface. The process is based on the construction of a reference plane on the scanned surface. The oil pan mounting surface is scanned by a 3D laser scanner, obtaining point cloud data that is then further processed to reduce noise. Using this processed data, a reference plane parallel to the direction of the mounting surface is defined at the mean position of the mounting surface. The direction of the reference plane is determined by the normal vector of the mounting surface. Construction of the reference plane is carried out by the singular value decomposition (SVD) technique. The deviation of the surface from the reference plane is measured by calculating the error distance between the points of the surface to the reference plane using the least-squares method.     

Design process to minimize roof surface defects using a flexural function and Finite Element analysis

The appearance and exterior precision of passenger cars aesthetics has become an important factor in the automotive industry. During vehicle assembly, the curvature of the roof can change slightly and create cosmetic defects that affect the exterior appearance. The critical factor causing curvature change on the roof is the thermally driven expansion of an elastomer-based mastic sealer which is applied between the exterior roof panel and support rail during the frame assembly process. Therefore the expansion of the mastic sealer was modeled to predict the curvature change in the roof panel. In order to evaluate the causes and predict the curvature change quantitatively, a Finite Element (FE) simulation of the oven heating and mastic curing was performed. Validation of the simulation model was performed by comparing the local deformation and amount of the curvature change on the roof obtained from the actual process. In order to minimize the curvature change, the Taguchi method was used in conjunction with the FE model where a total of eight factors were chosen to perform a sensitivity analysis. In order to exclude the deformation due to residual stress resulting from the oven process, it was selected as a noise factor. Response was taken as the maximum curvature change calculated by a flexural function which was used to distinguish absolute curvature that is not affected by the horizontal or vertical movement of roof panel. A total of 18 cases were analyzed with length of each sealer, pitch of sealer, and rail location being identified as the most influential factors affecting the curvature change. Using the optimum values, the amount of curvature change in the roof panel was reduced by 12 percent.     

Pressure model based coordinated control of VGT and dual-loop EGR in a diesel engine air-path system

This paper describes a pressure-model-based coordinated control method of a variable geometry turbine (VGT) and dual-loop exhaust gas recirculation (EGR) in a diesel engine air-path system. Conventionally, air fraction or burnt gas fraction states are controlled for the control of dual-loop EGR systems, but fraction control is not practical since sensors for fractions are not available on production engines. In fact, there is still great controversy over how best to select control outputs for dual-loop EGR systems. In this paper, pressure and mass flow states are chosen as control outputs without fraction states considering the availability and reliability of sensors. A coordinated controller based on the simple control-oriented model is designed with practical aspects, which is applicable for simultaneous operations of high pressure (HP) EGR, low pressure (LP) EGR, and VGT. In addition, the controller adopts the method of input-output linearization using back-stepping to solve the chronic problems of conventional pressure-based controllers such as coupling effects between operations of HP EGR, and VGT. The control performance is verified by simulation based on the proven GT-POWER model of a heavy-duty 6000cc diesel engine air-path.     

Automobile aerodynamics influenced by airfoil-shaped rear wing

Computational model is developed to analyze aerodynamic loads and flow characteristics for an automobile, when the rear wing is placed above the trunk of the vehicle. The focus is on effects of the rear wing height that is investigated in four different positions. The relative wind incidence angle of the rear wing is equal in all configurations. Hence, the discrepancies in the results are only due to an influence of the rear wing position. Computations are performed by using the Reynolds-averaged Navier-Stokes equations along with the standard k-ε turbulence model and standard wall functions assuming the steady viscous fluid flow. While the lift force is positive (upforce) for the automobile without the rear wing, negative lift force (downforce) is obtained for all configurations with the rear wing in place. At the same time, the rear wing increases the automobile drag that is not favorable with respect to the automobile fuel consumption. However, this drawback is not that significant, as the rear wing considerably benefits the automobile traction and stability. An optimal automobile downforce-to-drag ratio is obtained for the rear wing placed at 39 % of the height between the upper surface of the automobile trunk and the automobile roof. Two characteristic large vortices develop in the automobile wake in configuration without the rear wing. They vanish with the rear wing placed close to the trunk, while they gradually restore with an increase in the wing mounting height.     

Degree of fault isolability and active fault diagnosis for redundantly actuated vehicle system

This paper proposes á degree of fault isolability concept and active fault diagnosis method for redundantly actuated vehicle systems. Fault isolability is a structural property related to system dynamics and composition of actuators and sensors. Existing research on testing fault isolability has involved checking whether the system is isolable, i.e., binary in nature. A continuous value rather than a binary metric is needed to evaluate how isolable a given system fault is based on a specific measurement set. After fault components are isolated, the fault type and magnitude are estimated by analyzing residual vectors. In a redundantly actuated system, the number of controls/actuators is greater than the system mobility. Thus, the control input distribution to achieve a given control objective is not unique. In the case of a fault, the active fault diagnosis system adjusts the control input distribution to diagnose the fault. Thus, much more system information can be identified by additional excitation through a redundantly actuated system, which improves the fault diagnosis performance. Simulation results of a four-wheel independently driven and steered vehicle model validated the proposed degree of fault isolability and the effectiveness of the proposed active fault diagnosis method.     

隧道三维激光扫描测算一体化技术方案与实践北大核心CSCD

三维激光扫描技术已在隧道工程中得到广泛应用,但其内外业脱节、人工操作过多、实时性不足等问题日益凸显。文章结合工程实践,提出三维激光隧道扫描测算一体化技术方案,通过隧道设计模型录入、坐标里程解算、点云自动过滤、点云降采样与地物分离等,对点云进行特征值提取,得到兼顾规模、精度、效率的点云数据模型;通过点云与设计、点云与点云的对比解算,得到隧道工程质量安全相关成果。该技术方案在某铁路隧道工程中进行实践,可将内外业工作总时间缩短至20 min以内,自动化程度高,成果精度好,具有很好的推广价值。     

电力牵引系统用优化的传动机组

原边能源是电动汽车牵引系统中易造成故障的一个组件,力争对应用了成熟技术的发动机组进行优化.