Hierarchical Scheme of Vehicle Detection and Tracking in Nighttime Urban Environment

In this paper, we propose a novel hierarchical scheme for detection and tracking of vehicles using a vehicle-mounted camera in nighttime under urban environment, where a vehicle can be represented by a pair of taillights and various types of lights are commonplace. The proposed scheme, therefore, mainly focuses on devising robust detection and pairing of taillights in spite of their inherent diversity and continuous transformation in appearance. Thus the appearance symmetry, which many conventional methods rely on, for paring is not guaranteed to be available all the times. Each of the three layers in the scheme is devised to identify a vehicle from individual lights and clutters detected in a hierarchical manner. Robust detection of a pair of taillights, which can be regarded as a vehicle, is sought by successive groupings of the components in a layer and checking not only the intra-layer but the inter-layer relations between them. A structural Kalman filter is employed to maintain the temporal consistency in the motion of the components and their relations as well. Exploiting such relational information increases accuracy in tracking of individual components by reducing effects from fluctuation in positions and shapes, and eventually compensating possible failures in detection of them. As a result, the proposed scheme achieves enhancement in detection and tracking of vehicles in nighttime as proven by experiments on videos including crowded urban traffic scenes.     

Active response control of an offshore structure under wave loads using a modified probabilistic neural network

Offshore structures are subjected to wave, wind, and earthquake loads. The failure of offshore structures can cause sea pollution as well as loss of property and life. Therefore, the safety of such structures is an important issue. The reduction of the dynamic response of an offshore structure subjected to wind-generated random ocean waves is another critical problem with regard to the serviceability, fatigue life, and safety of the structure. In this article, the responses of offshore structures under random ocean waves are controlled using a modified probabilistic neural network (MPNN). As a more advanced method, it uses the global probability density function (PDF) produced by summing the heterogeneous local PDFs automatically determined from the individual standard deviation of each variable. The state vectors in a state-space model of a structure and the resulting control forces made by a linear quadratic regulator algorithm were used to generate the training patterns for the MPNN and a conventional multilayer perceptron (MLP). The results were compared with those produced by back-propagation based on the MLP. The proposed MPNN method shows good results not only in controlling the responses but also in terms of the computation time.     

A two‐leveled multi‐objective symbiotic evolutionary algorithm for the hub and spoke location problem

We consider a hub and spoke location problem (HSLP) with multiple scenarios. The HSLP consists of four subproblems: hub location, spoke location, spoke allocation, and customer allocation Under multiple scenarios, we aim to provide a set of well‐distributed solutions, close to the true Pareto optimal solutions, for decision makers. We present a novel multi‐objective symbiotic evolutionary algorithm to solve the HSLP under multiple scenarios. The algorithm is modeled as a two‐leveled structure, which we call the two‐leveled multi‐objective symbiotic evolutionary algorithm (TMSEA). In TMSEA, two main processes imitating symbiotic evolution and endosymbiotic evolution are introduced to promote the diversity and convergence of solutions. The evolutionary components suitable for each sub‐problem are defined. TMSEA is tested on a variety of test‐bed problems and compared with existing multi‐objective evolutionary algorithms. The experimental results show that TMSEA is promising in solution convergence and diversity.     

Conceptual design of high-speed semi-low-floor bogie for train-tram

Train-tram railway vehicles implement the connection between urban tramlines and the surrounding railway network. Train-tram railway vehicles, which use existing infrastructure, can help to avoid large investments in new railways or tramlines and make interchanges between city center and surrounding cities unnecessary. However, present train-tram rail vehicle cannot carry out the integration of operating by means of high speed in intercity railways with operating on small radius of curvature in inner city tramlines. This paper aims to develop a new model for solid wheelsets train-tram railway vehicles, which will not only pass the curve of 25mR radius of curvature traveling on inner city tramlines with the speed of 18 km/h, but also can travel on straight railway with 200 km/h high speed between intercity. In this paper, a new train-tram model, including five car-body and five motor bogies with ten traction motors, is addressed. Expect as a real rail vehicle testing, this study prefer virtual simulation, which is an effective way to show the rail vehicle performance, such as ride stability, ride comfort and ride safety, by means of evaluating the dynamic characteristics of rail vehicle. Moreover, Design of Experiment (DOE) method is used to optimize solid wheelsets bogie system on improving passenger comfort, safety and stability of train-tram. Parameters of components of bogie system are tuned to minimize the derailment coefficient and the ride comfort index. The results shows that the best comfort index for passenger and minimum derailment coefficient are found. The results also show that this optimized new train-tram model is reliable and practical enough to be applied on real rail vehicle design.     

Schedule construction under precedence constraints in flexray in-vehicle networks

As embedded time-triggered applications have widely replaced mechanical systems in modern automobiles, holistic scheduling of tasks and messages of such applications on in-vehicle networks has become a critical issue. For offering QoS (Quality of Service) guarantees, the holistic schedule must satisfy numerous constraints such as protocol specifications, delay constraints and precedence constraints between tasks schedules and messages transmissions. Existing approaches to this problem search through a vast design space of all possible joint task and message schedules. This leads to a high complexity and limits the scalability of such approaches for scheduling the large scale systems. To cope with this problem, we propose an approach that divides the holistic scheduling problem to two sub-problems: the sub-problem of message scheduling and the sub-problem of task scheduling, while precedence relations and end-to-end information passing between task instances and messages are preserved and the end-to-end deadlines are guaranteed. This helps to reduce the workload on the problem solvers and improves efficiency and scalability. In the first sub-problem, our approach optimizes scheduling the set of messages and allocates time windows for scheduling each task with respect to precedence constraints, end-to-end deadlines and FlexRay protocol specifications. The length of each time window helps to preserve the respective tasks schedulability and to provide flexibility for both task and message scheduling. The objective is defined with respect to extensibility issues. In the second sub-problem, our approach optimizes schedule of the set of tasks with respect to their allocated time windows and timing constraints. The objective is defined with respect to latency issues. We optimize the solution to each sub-problem using Mixed Integer Linear Programming optimization framework. Performance evaluations show that, compared with existing holistic scheduling approaches, our approach is more scalable and obtains better solutions in a reasonable amount of time.     

Travelers' preferences for in-vehicle information systems: An exploratory analysis

A sample of travelers' preferences toward in-vehicle traffic information systems was undertaken and appropriate statistical models were estimated. Specifically, ordered logit and regression analyses were conducted to quantify travelers' ratings of the importance of in-vehicle system attributes, and the distance ahead that they prefer to be notified of various types of information provided by in-vehicle systems. Model estimation results show that travelers' socio-economics, habitual travel patterns, commute congestion levels and attitudes toward in-vehicle technologies are significant determinants of travelers' importance ratings and the preferred distance ahead of in-vehicle system information. These model results provide important information for both marketing and design of in-vehicle information systems.     

Estimation of valve spring surge amplitude using the variable natural frequency and the damping ratio

Internal vibration of the valve spring is a critical factor in determining the dynamic characteristics of high-speed valve train systems. Because precise prediction of the spring surge amplitude is a difficult problem, especially for nonlinear variable-pitch springs, the development stage requires a process of trial and error. In the present study, a new method that considers the variable natural frequency and variable damping ratio is proposed to predict the spring surge amplitude. First, the change in the natural frequency and damping ratio caused by compression is predicted from the initially given pitch curve at the free height. Second, the spring surge amplitude is estimated by solving the wave equation with nonlinear variable coefficients. The surge amplitudes of typical valve springs are also measured using a motoring test rig and are compared with theoretical results predicted by the spring drawing and cam profile data.     

Measurement of the disc-pad friction coefficient for mechanical brakes using direct and indirect methods

It is necessary to guarantee the proper brake force to stop a train safely in a limited distance and o adjust its speed. Currently, most trains are run by electrical power and have a combined electrical and mechanical (friction) braking system. The mechanical brake force is determined by many parameters, such as the friction coefficient of the brake disc and pad, the pressure in the brake cylinder, the brake cylinder’s cross sectional area and the brake linkage ratio. In general, the friction coefficient data of the brake disc and pad have been taken through a dynamo-test in a laboratory, but these data might not be well matched with real data under operating conditions because of the difference in data acquisition conditions. The present study examined two methodologies that can measure the friction coefficient of the brake pad and disc based on a train’s real operating conditions. The first method was the direct method, which measured the brake force and clamping force applied on the mechanical brake by using strain gauges installed on the brake to calculate the friction coefficient. The second was an indirect method that obtained the friction coefficient by using the weight of the train and the equivalent brake force. Those variables were calculated from the longitudinal dynamic characteristics, such as resistance to motion, gradient resistance and curved resistance. These two methodologies were used to obtain the disc-pad friction coefficient for the mechanical brakes of a Korean high-speed train (HSR350x).     

Effect of a 2-stage injection strategy on the combustion and flame characteristics in a PCCI engine

Recently, to reduce environmental pollution and the waste of limited energy resources, there is an increasing requirement for higher engine efficiency and lower levels of harmful emissions. A premixed charge compression ignition (PCCI) engine, which uses a 2-stage type injection, has drawn attention because this combustion system can simultaneously reduce the amount of NOx and PM exhausted from diesel engines. It is well known that the fuel injection timing and the spray angle in a PCCI engine affect the mixture formation and the combustion. To acquire two optimal injection timings, the combustion and emission characteristics of the PCCI engine were analyzed with various injection conditions. The flame visualization was performed to validate the result obtained from the engine test. This study reveals that the optimum injection timings are BTDC 60° for the first injection and ATDC 5° for the second injection. In addition, the injection ratio of 3 to 7 showed the best NOx and PM emission results.     

Development of a telematics evaluation environment based on a driving simulator and its application

For developing telematics devices, traditional development methods include the unit function test, compatibility test and T-Car, which have some limitations. Telematics devices have various functions that require accounting for the interactions among three major elements of automotive electronics: the vehicle, the device unit and driver. The KAAS (KATECH Advanced Automotive Simulator) system is a virtual-reality-based test environment designed to test and analyze the three elements in one place. One of the difficult functions when constructing such VR (Virtual Reality)-based telematics test environment is to develop a test method for the LBS (Location-Based Service) function such as a car navigation demanding the GPS (Global Positioning System) satellite signals because KAAS is in a fixed laboratory. To overcome these problems, a real-time GPS simulation system, which can be integrated with KAAS, is needed because the location of the vehicle in virtual space is determined purely by the driver’s personal intention while driving virtually. This paper presents new concepts needed to construct a VR-based telematics test environment to generate a GPS RF signal, which reflects the continuously changing vehicle location during virtual driving in real-time. To construct this system, the coordinate transform must be conducted from a rectangular coordinate system that is compatible with a virtual 3D DB that is used to construct a 3D image for KAAS using a WGS84 and a longitude-latitude coordinate system compatible with a GPS simulator. Moreover, the real-time HILS (Hardware In Loop Simulation) systems and the CDMA (Code Division Multiple Access) simulation system are developed to evaluate telematics devices. Finally, we show its applications and results.