Prediction of wave parameters by using fuzzy inference system and the parametric models along the south coasts of the Black Sea

Forecasting of sea-state characteristics has a great importance in coastal and ocean engineering studies. Therefore, the purpose of this study was to investigate performances of Adaptive-Network-Based Fuzzy Inference System (ANFIS) and several parametric methods in the Black Sea. For this purpose, different fuzzy models with different input combinations were developed for two different wind data sources (TSMS and ECMWF) at two offshore buoy stations. It also aimed to apply several approaches to event-based data sets for wave predictions. Generally, in literature the tendency is to use time series data for wave predictions. In this kind of prediction approach, lagged time series data are taken as inputs and current or future variables are taken as output. In this study, event-based data for each independent storm were extracted from time series data. Simultaneous or concurrent data of wind speed, blowing duration, fetch length and wave characteristics were detected for each single storm. These event data were then used to set up models. The hindcast results were validated with significant wave height and mean wave period data recorded in Hopa and Sinop buoy stations. The performance of developed fuzzy models were also compared with that of four different parametric methods (Wilson, SPM, Jonswap, and CEM methods) applied for two wind data sources at both buoy stations. Finally, it was determined that in the prediction of both wave parameters (H _s and T _z) the ANFIS models (R = 0.66, squared correlation coefficient, and MAE = 0.37 m, mean absolute error, for the best model in prediction of H _s) were more accurate than the parametric methods (R = 0.63 and MAE = 0.75 m for the best model in prediction of H _s).     

飞机降落冲击荷载作用下高铁隧道动力响应及疲劳损伤研究北大核心CSCD

针对运营期高铁隧道衬砌结构在飞机降落冲击荷载作用下的动力响应规律及疲劳损伤问题,以成自高铁下穿天府机场东二跑道区间隧道为工程背景,采用有限元分析的方法研究隧道动力响应及疲劳损伤规律。结果表明:B747-400型飞机在粗暴着陆后0.05 s时刻动力载荷达到最大值,约为500 kN;在单次粗暴着陆工况下,拱顶位移和受力最大,位移最大峰值为1.58 mm,拉应力最大峰值为437.79 kPa,压应力最大峰值为556.24 kPa,衬砌结构未出现塑性损伤;飞机荷载长期作用下,随着循环次数的增加,结构损伤部位和程度也随之增加,拱顶损伤最突出,其次为边墙,隧道衬砌在上方飞机长期粗暴着陆作用下的疲劳寿命大致为25 a。     

Vehicle detection system design based on stereo vision sensors

Vehicle detection is a crucial issue for driver assistance system as well as for autonomous vehicle guidance function and it has to be performed with high reliability to avoid any potential collision. The vision-based vehicle detection systems are regarded promising for this purpose because they require little infrastructure on a highway. However, the feasibility of these systems in passenger car requires accurate and robust sensing performance. In this paper, a vehicle detection system using stereo vision sensors is developed. This system utilizes feature extraction, epipoplar constraint and feature matching in order to robustly detect the initial corresponding pairs. The proposed system can detect a leading vehicle in front and can estimate its position parameters such as the distance and heading angle. After the initial detection, the system executes the tracking algorithm for the vehicles in the lane. The proposed vehicle detection system is implemented on a passenger car and its performances are verified experimentally.     

Analysis of a regenerative braking system for Hybrid Electric Vehicles using an Electro-Mechanical Brake

The regenerative braking system of the Hybrid Electric Vehicle (HEV) is a key technology that can improve fuel efficiency by 20∼50%, depending on motor size. In the regenerative braking system, the electronically controlled brake subsystem that directs the braking forces into four wheels independently is indispensable. This technology is currently found in the Electronic Stability Program (ESP) and in Vehicle Dynamic Control (VDC). As braking technologies progress toward brake-by-wire systems, the development of Electro-Mechanical Brake (EMB) systems will be very important in the improvement of both fuel consumption and vehicle safety. This paper investigates the modeling and simulation of EMB systems for HEVs. The HEV powertrain was modeled to include the internal combustion engine, electric motor, battery and transmission. The performance simulation for the regenerative braking system of the HEV was performed using MATLAB/Simulink. The control performance of the EMB system was evaluated via the simulation of the regenerative braking of the HEV during various driving conditions.     

Grain refinement in bearing steels using a double-quenching heat-treatment process

A double-quenching (D/Q) process is proposed for heat-treating high carbon-chromium bearing steels to improve the fatigue properties through refinement of the microstructure. The new heat treatment method has two steps: The first step is a nitrocarburizing process that results in high surface hardness and lowers the transformation temperature. The second step is the same as in the conventional quenching process but can be conducted at a considerably lower temperature than in conventional quenching. The microstructure in the material that is caused by the D/Q heat treatment is much finer than in the conventional Q/T (quenching and tempering) process. In order to quantify the performance of the proposed heat-treatment process, various mechanical property tests are carried out. The rolling contact fatigue life of double-quenched bearing steels was eight times higher than in bearing steels that were treated by conventional Q/T.     

A Novel Image Encryption Technique Based on Inter Block Difference

Data security plays a vital role in the current scenario due to the advanced and sophisticated data access techniques.Present development in data access is alwa...     

On incentives and optimal effort to improve bus transit performance

ABSTRACT

This paper studies incentive-based subsidy to transit systems to improve performance. It derives a formula for optimal effort that equalizes marginal cost and marginal benefit and derives some principles from it among which is that the larger the value of a transit system’s performance criterion the larger the effort it will exert to improve it. Next, using a constrained cost minimization approach it derives a nonlinear cost function that includes optimal effort and estimates it using an unbalanced panel data of single mode U.S. bus transit systems. The results show that optimal effort is the equivalent of seven full-time employees (15,243 labor hours) per year and in real terms it results in 0.6% cost saving (US$198,331) and US$836,796 in incentive subsidy per observation. The implications of these findings are examined.     

Freight generation and geographical effects: modelling freight needs of establishments in developing economies and analyzing their geographical disparities

Transportation - Freight generation (FG) models are important to transportation authorities and planning agencies as they can be used to forecast local/regional/state/national freight movements for...     

On the beaten track: a view of US West-Coast container port competition

More than a century ago far-sighted railroad builders and steamship operators were seeking the shortest intermodal itineraries between the eastern United States and the Orient. A combination of locational fact and the factual outcomes of 19th century railroad building left Chicago roughly equidistant in railway mileage from what became the four great US West-Coast port complexes in the Los Angeles, San Francisco, Portland and Seattle regions. Their nearly equivalent rail access to Chicago and points east has renewed significance in the container era.

This paper concerns the efforts of US Pacific seaboard ports to stay 'on the beaten track' with respect to container shipments between Asia and the eastern United States. The West-Coast ports are transit points dividing the transcontinental and transoceanic segments of long intercontinental journeys. From origins to destinations there are, in fact, many possibly feasible itineraries, including all-water routes.

The West-Coast ports have considerable control over their own site improvements. On the other hand, with respect to transiting container traffic, the ports may influence, but are unlikely to control, their own situations. Since the major container port facilities are very often on long-term lease to large intermodal carriers, the latter are making the important shipping and routeing decisions. The carriers tend in fact to set the tone and level of port competition.

What is the nature of the competition between container ports? Is it a figment of the publicist's imagination and perpetuated by irrelevant statistical boasting? Is it perhaps something forced on the ports by carriers eager to play one port off against another in a 'lowest bid' game? At what geographical scale might port competition be most useful or, maybe, least wasteful?