Cycle-simulation turbulence modelling of IC engines

Numerical simulations of IC engines are of high interest for automotive engineers worldwide. The simulation models should be as fast as possible, low-computational effort and predictive tool. The correct prediction of turbulence level inside the combustion chamber of spark ignition engines is the most important factor influencing to the engine working cycle. This paper presents a development of the k-ε turbulence model applied to the commercial cycle-simulation software with the high emphasis on the intake part. The validation was performed on two engine geometries with the variation of engine speed and load comparing the cycle-simulation results of the turbulent kinetic energy and in-cylinder temperature with 3-D CFD results. In order to apply the cycle-simulation turbulence model for the simulation of entire engine map, the parameterization model of turbulence constants was proposed. The parameterized turbulence model was optimized using NLPQL optimization algorithm where the single set of turbulence model parameters for each engine was found. A good agreement of the turbulent kinetic energy during the expansion was achieved when the turbulence affects the flame front propagation and combustion rate as well.     

Modelling and control of a new differential steering concept

This paper presents a new steer-by-wire concept using an all-wheel drive vehicle layout with in-wheel motors while completely omitting the application of any dedicated steering device. Steering is based on the so-called differential steering principle which generates the necessary steering moment about the kingpins by a traction force difference between left and right sides of the vehicle. In order to investigate the behaviour of the vehicle and to design the underlying control algorithms, a planar vehicle model is presented, where the vehicle is described as constrained non-holonomic system requiring a special treatment. A state feedback linear controller for controlling of the lateral dynamics of the vehicle at higher speeds and a simple PI angle controller for low-speed manoeuvring are developed. The resulting behaviour of the system is investigated by various simulation experiments demonstrating a comparable steering performance of the new steering concept as that of conventional passenger cars.     

3D brush model to predict longitudinal tyre characteristics

A 3D tyre brush model, which aims to predict the longitudinal tyre characteristic under steady-state conditions by modelling the occurring physical effects in the tyre–road contact patch, is presented. The model includes an analytical method to describe the tyre footprint geometry, the pressure distribution, the slip due to the lateral tyre contour, the slip due to braking or traction and the longitudinal as well as the lateral shear stresses on a flattened tyre. The presented development tool offers a method to investigate different rubber friction data (caused by different tread compounds and/or surface textures) and to analyse its influence on longitudinal tyre characteristics. The tyre design is fixed (same casing, dimension and pattern). The results include the shear stresses as well as the different sliding velocities in the contact patch for different slip conditions. The model was developed for a standard summer pattern design and a standard tyre dimension (205/55R16). It can also be adapted to other tread designs and tyre dimensions. To offer a good comparability between model results and test bench measurements, the surface curvature of an internal test rig is considered.     

Estimation of the effects of aircraft noise on residential satisfaction

This study assesses the effects of aircraft noise on residential satisfaction, an important indicator of subjective well-being. A structural equation model is specified that estimates the relationships between objective variables, noise annoyance variables and residential satisfaction. Secondary data-analysis is used to estimate the model. The survey was conducted in 1996/1997 among the population living within a 25-km radius of Amsterdam Schiphol, the largest airport in the Netherlands. The effect of aircraft noise annoyance is found to be relatively small. In addition, the objective level of aircraft noise exposure is found to be a better predictor of residential satisfaction than its subjective counterpart. The most important determinants of residential satisfaction are found to be road traffic noise annoyance, age and neighbor noise annoyance.     

Methodology for the accuracy improvement of FEM beam type T-junctions of buses and coaches structures

The analysis of structures with finite elements methods (FEM) represents a widely spread technique. For large tubular structures similar to the buses and coaches upper structures, beam type elements are utilized due to the fact that these elements provide satisfactory results at relatively reduced computational performances. However the beam type elements have a main disadvantage determined by the fact that the modeled joints have an infinite rigid behavior. This shortcoming determines a stiffer behavior of the modeled structures which translates into an error source for the structural simulations (up to 45%). To overcome this problem, a simple methodology was conceived and an alternative optimized equivalent beam model obtained. The methodology studies the behavioral characteristics of beam modeled T-junctions determining their limitations and comparing them to equivalent T-junctions modeled with shell and volume elements. This way an improved Tjunction has been obtained, in which the behavioral error was reduced to less than 5%. Furthermore the FEM obtained results were validated with real T-junctions.     

Finite element modeling of static tire enveloping characteristics

To investigate static tire enveloping characteristics, a three dimensional (3-D) finite element model is proposed. The vertical stiffness of the tire is studied on a flat surface with and without cleat. Tire rubber materials and cord layers are represented independently using “rebar” elements available in MSC Marc Mentat. Comparisons of numerical and experimental results are given to show the validity of the proposed model. It is shown that after a certain displacement, the results of the proposed model agree well with experimental results. In addition, the model results show that regardless of the type of the cleat placed under the rim center (hub center), all vertical force curves intersect after a certain displacement, which indicates typical static enveloping characteristics. Moreover, another typical characteristic of the radial tires that is unlike those of bias-ply constructions confirms that the contact patch does not expand laterally after a level vertical load is applied to the tire, which is directly related to fuel consumption and tire tread life.     

Global supply chain and port/terminal: integration and competitiveness

Much has been said of the importance of port and terminal integration in the supply chain. Authors have stressed the importance of agility to the port environment, which involves being proactive along supply chains, facilitation of intermodal integration, as well as organizational integration and partnership between ports and users. Despite the well articulated importance of the issues, little has been offered in terms of conceptualizations and empirical evidence of what really is meant by port/terminal integration in the supply chain, how such integration can be measured and quantified as well as the extent to which different ports/terminals in the world are integrated in the supply chain and competitive performance implications arising thereof. This paper aims to make a contribution in this respect by (i) reviewing the relevant literature on supply chain integration and port integration in the supply chain, (ii) conceptualizing measures for port/terminal integration in the supply chain, (iii) empirically testing the influence of port/terminal integration in the supply chain on port competitiveness and (iv) outlining the significance and value of the study for port operators, shipping lines, transport providers and for further research.     

Ship, port and supply chain security concepts interlinking maritime with hinterland transport chains

As maritime processes do no stop at sea ports, hinterland operations have to be considered and addressed as well. This becomes obviously on designing and managing seamless cargo and information flows from/to hinterland regions via sea ports from/to transcontinental markets. Nowadays, also security-related aspects need to be tackled in order to enable continuous flows corresponding to security legislations and technical requirements set up in the field of maritime and intermodal hinterland transport. Ensuring transport security within the European transport market requires both adequate security legislations and innovative concepts. While for the maritime sector, including sea ports, security regulations are already in force, hinterland operations (road, rail and Inland Waterway Transport) are only indirectly affected today, either on carrying out transports from/to sea ports or exporting commodities to overseas territories. This results in the need for innovative security strategies and concepts combining maritime with hinterland transport enabling seamless security processes.     

中国与海事经济：下一阶段

以时间和船只数目来量度，航运市场正处于两百年来最兴旺的时期。中国是这段兴旺时期的最大功臣，它的贡献已被广泛讨论。经过10年的快速增长，中国对海事行业的影响正进入一个新阶段，演变中的中国经济对整个世界海事行业和中国造船业带来新挑战。     

Development of hot stamped center pillar using form die with channel type indirect blank holder

The hot stamping process has been used in the automotive industry to reduce the weight of the body-in-white and to increase passenger safety via improved crashworthiness. However, defects such as fracture and wrinkle occur when hot stamping is performed using a conventional drawing or forming method. In this study, a channel-type indirect blank holder (CIBH) is proposed to develop a high-strength center pillar in form-type hot stamping, so that the aforementioned drawbacks are overcome. This type of blank holder plays an important role in reducing severe wrinkling at the flange; such wrinkling leads to folding after the completion of form-type hot-stamping. First, we investigated the effect of the channel shape on the indirect blank holding force by using a simplified two-dimensional plane-strain stamping process. Second, we selected the slope angle and corner radius of the channel as the main shape parameters by finite element analysis and artificial neural network (ANN). It is known that fracture at the hot formed wall and wrinkle at the flange are significantly affected by the slope angle of the channel, and the appropriate value for eliminating fracture and wrinkle is determined to be 99°. By performing hot stamping using a form die with the selected channel, we can manufacture a high-strength center pillar without wrinkle and fracture.