Traffic planning of Kejetia: The piccadilly circus of Kumasi,Ghana

This article derives from a study concerned with the traffic implications of a proposed redevelopment of the Central Market in Ghana's second largest city, Kumasi, which is situated almost in the geographic centre of the country. The market adjoins a big roundabout which is located at the point of intersection not only of north-south national routes but also at a point on which most of the city's main roads carrying cross-town traffic converge. The problem of traffic in terms of accessibility and environment is described in relation to the functions of the market. This is compared with a similar situation in London's Piccadilly Circus. Based on the results of traffic surveys and an analysis of the urban structure, alternative solutions to the problem in Kumasi are examined and tested using traffic assignment techniques. Consequently, on the basis of accessibility and environmental requirements, proposals are made as to the best line of action to take. The article ends with some lessons of the study.     

Optimal Control of a Vehicle Suspension Incorporating the Time Delay between Front and Rear Wheel Inputs

An optimal control law for a vehicle suspension is developed using a discrete linear quadratic regulator framework. The time delay between the disturbance due to the road at the front and rear wheels is incorporated into the model, and it is shown that the optimal control law requires information gathered at the front wheels. A comparison is made between the optimal control law and a suboptimal one which does not incorporate front wheel road information.     

Research on the Mechanical Properties of Transparent Sand Based on Triaxial TestEI北大核心

Research purposes: Transparent sand is a new type of geotechnical engineering material, which is made of fused silica sand and porous liquid with the same refractive index. In order to understand its mechanical properties, the CU and CD tests of fused silica sand with a particle size of 0.5~1.0 mm and 1.0~3.0 mm are carried out by triaxial apparatus, and the stress-strain curves, pore water pressure changes and effective stress ratio of the two are compared and analyzed. In addition, E-μ model parameters of coarse and fine sand are calculated respectively, which provide corresponding parameters for further numerical calculations. Research conclusions:(1) The loose sample's stress-strain curve shows hardening characteristics. (2) The coarse particle specimen with steeper stress-strain curve comes to the peak at faster velocity than fine particle specimen. (3)The pore pressure value of the coarse particle specimen is greater than the fine particle, the pore water pressure coefficient of the two shows a decreasing trend with the increase of the confining pressure. (4) Transparent sand can be used to simulate natural sand and the change of diameter can represent different soils. (5) The research results can provide reference for model tests based on transparent soil technique. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Motion cueing in high-performance vehicle simulators

The majority of motion cueing algorithms have been developed for passenger car applications, with correspondingly less research dedicated to race-car and high-performance vehicle simulators. In the high-performance context, the focus is on cueing the vehicle's behavioural and handling characteristics, particularly when driving near the limits of performance. In race-car simulators the cueing requirements are therefore quite different, with the problem made all the more challenging by the presence of large accelerations. To understand the drivers' cueing needs, the vehicle's stability and handling response characteristics must be examined near the performance boundary. Frozen-time eigenvalue analyses are used to determine stability and response characteristics across all vehicle operating conditions, including accelerating and braking under cornering, with the results used to determine motion cueing algorithm requirements. Lateral acceleration and yaw cueing filters are designed in order to retain information critical to understanding the vehicle's behaviour on its performance boundary. Cueing filters are then tested, with the help of a professional race-car driver, and are found to provide the cues necessary for the driver to control the vehicle on the limit of performance.     

Gain scheduled linear quadratic tracking system tuned optimally by covariance matrix adaption evolutionary strategy for automotive engine coldstart control

In this paper, a gain scheduled linear quadratic tracking system (LQTS) tuned optimally by an evolutionary strategy (ES) is devised to reduce the total tailpipe hydrocarbon (HC) emissions of an automotive engine over the coldstart period. As the engine’s behavior during coldstart operations is nonlinear, the system dynamics is clearly analyzed and represented by a number of separate linear models generated based on a coldstart model verified by experimental data. An independent LQTS is then implemented for each of these linear models. In this way, several control laws are created, and the corresponding gains are calculated for each of the independent control laws. ES is then used to tune the adjustable parameters of LQTSs to calculate the control inputs, namely air/fuel ratio (AFR) and spark timing (Δ), such that the resulting exhaust gas temperature (T _exh) and engine-out HC emissions (HC _raw) be close to a set of optimum profiles. This enables the controller reduce the cumulative tailpipe hydrocarbon emissions (HC _cum) to the highest possible extent. To demonstrate the acceptable performance of the proposed controller, an optimal controller derived from the Pontryagin’s minimum principle (PMP) is also taken into account. Based on the results of the conducted comparative study, it is shown that the proposed control technique has a very good performance, and also, can be easily used for real-time applications, as it consumes a remarkably trivial computational time for calculating the controlling commands.     

Self-Excited Vibrations of Railway Vehicle with Dry Friction Units

Some results obtained during developing a new approach to analysis of conditions of self-excitation of lateral vibrations of railway vehicles as systems of variable structure are given in this article. Structure variability is conditioned by the state of constraints with dry friction. An idea of the replacement of a nonlinear multibody system by a number of subsystems, which are linearized in a certain way, is worked out. The efficiency of the method suggested for the determination of the characteristics of self-excited vibrations of active multibody systems with dry friction is illustrated by way of an example of the investigation of the dynamic behaviour of a freight car.     

Drowsy behavior detection based on driving information

Drowsy behavior is more likely to occur in sleep-deprived drivers. Individuals’ drowsy behavior detection technology should be developed to prevent drowsiness related crashes. Driving information such as acceleration, steering angle and velocity, and physiological signals of drivers such as electroencephalogram (EEG), and eye tracking are adopted in present drowsy behavior detection technologies. However, it is difficult to measure physiological signal, and eye tracking requires complex experiment equipment. As a result, driving information is adopted for drowsy driving detection. In order to achieve this purpose, driving experiment is performed for obtaining driving information through driving simulator. Moreover, this paper investigates effects of using different input parameter combinations, which is consisted of lateral acceleration, longitudinal acceleration, and steering angles with different time window sizes (i.e. 4 s, 10 s, 20 s, 30 s, 60 s), on drowsy driving detection using random forest algorithm. 20 s-size datasets using parameter combination of accelerations in lateral and longitudinal directions, compared to the other combination cases of driving information such as steering angles combined with lateral and longitudinal acceleration, steering angles only, longitudinal acceleration only, and lateral acceleration only, is considered the most effective information for drivers’ drowsy behavior detection. Moreover, comparing to ANN algorithm, RF algorithm performs better on processing complex input data for drowsy behavior detection. The results, which reveal high accuracy 84.8 % on drowsy driving behavior detection, can be applied on condition of operating real vehicles.     

Effects of air supply diffusers and air return grilles layout on contaminants concentration in bus passenger compartment

Ventilation system in a bus is employed to provide good indoor air quality and thermal comfort for passengers. Poor ventilation system will increase the concentration level of air contaminants which could affect the passenger’s health. The presence mixing ventilation system used in many buses is not efficient in removing the air contaminants from the passenger compartments. This article presents a study on the effects of using different ventilation setups on the concentration level of gases and particulate matters inside a passenger compartment of a university’s shuttle bus. The goal is to find a suitable layout of the air supply diffusers and air return grilles that would lower the concentration level of contaminants inside the passenger compartment. Field measurements were carried out to quantify the concentration of gases (carbon monoxide, carbon dioxide and formaldehyde) and particulate matters (PM1, PM2.5 and PM10). The measurements were done at the front section of the bus compartment, close to the front door. The data were acquired in the morning, afternoon and evening hours during a clear and sunny day. The bus travelled along an in-campus road with no passengers. A simplified three-dimensional model of the bus compartment was developed using computational fluid dynamics software. Flow analyses were carried out to predict distribution of gases and particulate matters concentration. The concentrations of carbon dioxide, carbon monoxide, formaldehyde and particulate matters obtained from the field measurements were used as boundary conditions and for validating the computational model. A parametric study was carried out to identify a suitable layout of air supply diffusers and air return grilles that would lower the concentration level of the air contaminants. Two types of ventilation systems were considered namely a displacement ventilation and an underfloor air distribution. Results show that the underfloor air distribution system is more effective in reducing the concentration level of gases and particulate matters inside the passenger compartment compared to the displacement ventilation system.     

Swimming for survival: A role of phytoplankton motility in a stratified turbulent environment

We investigate a role for vertical migration in stratified coastal water, where the swimming speed is generally significantly less than the typical turbulent fluctuations in a tidally-mixed bottom layer. In our modelling approach we use a k- turbulence model to describe the physical forcing, a Lagrangian random walk model to describe the vertical displacement of individual cells in response to turbulence and due to cell motility, and a phytoplankton growth model to direct the swimming behaviour of the phytoplankton according to their light and nutrient requirements. The model results show how the cells form a stable subsurface chlorophyll maximum (SCM) at the base of the thermocline where episodic tidal turbulence causes erosion of part of the SCM biomass into the bottom mixed layer (BML). We then focus on the question of whether an ability to swim (weakly, compared to typical bottom layer turbulent intensities) provides any advantage by allowing return to the SCM. Our results show that tidal turbulence in the BML helps both motile and neutrally-buoyant cells by periodically pushing them into the base of the thermocline. Motile cells then have the advantage that they can swim further into the thermocline towards higher light which also reduces the likelihood of being re-mixed back into the BML.     

Neural network model for designing automotive devices using SMD LED

The advantages offered by the electronic component LED (Light Emitting Diode) have resulted in a quick and extensive application of this device in the replacement of incandescent lights. In this combined application, however, the relationship between the design variables and the desired effect or result is very complex and renders it difficult to model using conventional techniques. This paper consists of the development of a technique using artificial neural networks that makes it possible to obtain the luminous intensity values of brake lights using SMD (Surface Mounted Device) LEDs from design data. This technique can be utilized to design any automotive device that uses groups of SMD LEDs. The results of industrial applications using SMD LED are presented to validate the proposed technique.