A new functional optimization method applied to the pitch distribution of a marine propeller

Based on Hilbert space theory, an infinite-dimensional optimization method to find the optimal pitch distribution of marine propellers was developed. Thereby, the three-dimensional effect of induced velocity could effectively be controlled in an optimal way; i.e., an investigation was carried out to learn whether the present method is applicable to the design of marine propellers, especially pitch distributions, by maximizing the propeller efficiency functional. In addition, with the help of Hilbert space theory, it was successfully shown that the optimization method developed has a unique mathematical solution. In this work, only the pitch distribution was optimized, while other parameters such as the camber and thickness of the trial propeller remained as in the original. With a numerical study, it is shown that the present optimization method gives an optimal pitch distribution, the open-water characteristic curve being superior to the original curve. Received: August 24, 2000 / Accepted: July 16, 2001     

海洋结构物沉箱吸附力的试验模拟

吸附力是海洋和港口工程中常见的一种力,一般是指位于海底软粘土中的沉箱或其他坐底式结构等建筑物,在起浮过程中,底面与软土之间相互作用所产生的力。吸附力是影响结构物起吊的主要阻力,研究吸附力可为合理选用起浮设备提供依据,对实际工程有着重要意义。     

基于μC/OS-Ⅱ的汽车CAN总线智能节点的设计

在将嵌入式操作系统μC/OS-Ⅱ成功移植到LPC2129的基础上,给出了基于ARM7内核的LPC2129汽车CAN总线硬件电路,详细阐述了基于嵌入式操作系统μC/OS-Ⅱ的智能节点软件设计方法.     

Prediction of steel plate deformation due to triangle heating using the inherent strain method

In a shipyard, line heating and triangle heating are two major processes carried out by skilled workers to form curved plates in various shapes under various heating conditions. There have been many studies on line heating, but triangle heating has rarely been studied owing to its complicated heating process with irregular multiheating paths and highly concentrated heat input. Triangle heating is the most labor-intensive job. Hence, it is essential for most shipyards to study the automation, as well as the improvement, of the triangle heating process in order to increase hull-forming productivity. In this study, a pioneering attempt to simulate triangle heating was made. A circular disk-spring model is proposed as an analysis model for the elastoplastic procedure of triangle heating, and the inherent strain method is also used to analyze the deformation of plates. The results of the simulation were compared with those of experiments and showed good agreement. It is shown that the present approach and the model used in this study are effective and efficient for simulating triangle heating for the steel plate forming process in shipbuilding.     

Driving Pattern Recognition for Control of Hybrid Electric Trucks

The design procedure for an adaptive power management control strategy, based on a driving pattern recognition algorithm is proposed. The design goal of the control strategy is to minimize fuel consumption and engine-out NOx and PM emissions on a set of diversified driving schedules. Six representative driving patterns (RDP) are designed to represent different driving scenarios. For each RDP, the Dynamic Programming (DP) technique is used to find the global optimal control actions. Implementable, sub-optimal control algorithms are then extracted by analyzing the behavior of the DP control actions. A driving pattern recognition (DPR) algorithm is subsequently developed and used to classify the current driving pattern into one of the RDPs; thus, the most appropriate control algorithm is selected adaptively. This 'multi-mode' control scheme was tested on several driving cycles and was found to work satisfactorily.     

女性下生殖道尖锐湿疣322例临床分析

本文对322例女性下生殖道尖锐湿疣的临床特点作了分析,指出激光辅以用药是较理想的治疗方法,一次治愈率为78.37%。本文讨论了妊娠合并尖锐湿疣与癌的关系,322例中癌变6例,重度非典型增生1例,癌变率为1.86%。     

On the nonlinear and time-varying acoustic modeling of the simplified intake or exhaust silencing system

The intake or exhaust noise of an internal combustion engine is usually predicted by the linear, time-invariant source model in frequency domain with reasonable precision. However, the actual finite amplitude pulsation involves the nonlinear, time-varying characteristics that are prominent in time-domain. To overcome the discrepancy between two source models, an approximate nonlinear and time-varying frequency domain source model can be employed by appending the nonlinear or time-varying terms to the linear, time-invariant source model. Proper selection of the nonlinear describing terms varying with time is important for the realistic and precise prediction of the radiated sound. For the selection of such terms, flow and motional characteristics in the valve and orifice of a simplified fluid machine comprised of very large reservoir, valve, and duct is considered. Effects of each describing term and the combined terms are investigated by comparing the sound spectrum predicted from nonlinear source model to that from linear source model. In the comparison, the sound spectrum calculated by the method of characteristics is used as a reference. It is found that the source model using only the velocityrelated terms yields the best result among all the models using various combinations of the terms with different characteristics. The best model yields a difference from the linear source model within ±5 dB in overall sound level. Change of acoustic loads results in a difference of 20–27 dB in linear source model from the reference data; however, maximum 10–22 dB deviations are observed in using the various nonlinear source models. It is concluded that more than 4 describing terms should be employed in the nonlinear model to obtain a realistic result of the radiated sound from the intake or exhaust system.     

Development of an electric active rollcontrol (ARC) algorithm for a SUV

Cornering maneuvers with reduced body roll and without loss in comfort are leading requirements for car manufacturers. An electric active roll control (ARC) system controls body roll angle with motor-driven actuators installed in the centers of the front and rear stabilizer bars. A vehicle analysis model developed using a CarSim S/W was validated using vehicle test data. Two ARC algorithms for a sports utility vehicle (SUV) were designed using a sliding-mode control algorithm based on a nonlinear roll model and an estimated lateral acceleration based on a linearized roll model. Co-simulation with the Matlab simulink controller model and the CarSim vehicle model were conducted to evaluate the performance of two ARC control algorithms. To validate the ARC performance in a real vehicle, vehicle tests were conducted at KATECH proving ground using a small SUV equipped with two ARC actuators, upper and lower controllers and a few subsystems. From the simulation and vehicle validation test results, the proposed ARC control algorithm for the developed ARC actuator prototypes improves the vehicle’s dynamic performance.     

Optimum SUV bumper system design considering pedestrian performance

Until recently, passenger cars have primarily interested in pedestrian protection performance. Nowadays, however, it is important for a sport-utility vehicle (SUV) to meet the bumper system standards for pedestrian safety. For a SUV bumper system, there are some difficulties in attaining a high level of pedestrian performance for the lower legform. An SUV has a high bumper position from the ground level, and the bumper approach angle must also be secured, which has an effect on car insurance fees. Due to these reasons, it is difficult to meet the pedestrian performance of the lower legform for an SUV. In this paper, a comparative study was performed on various SUV bumper systems, and a concept model for a SUV bumper system was developed, which is expected to meet the pedestrian performance by using the Pugh method. The design control factors were defined to affect the bumper pedestrian performance through the experiences of tests and analyses. For the noise factor to affect the pedestrian performance, the deviation of the impactor position was selected at the moment of impact. The design control factors were optimized by using the Taguchi optimization technique. For the Taguchi method, an L18 orthogonal array table of design control factors was used in the optimization process. Particularly, for the optimization of the bumper corner region, an optimization analysis was performed three times to meet pedestrian performance. Based on the results of the Taguchi optimization method, the sensitivity of the bumper design parameters was studied, and a new SUV bumper system is proposed that satisfies the pedestrian performance of the lower legform. The optimized bumper system should obtain a full Euro-NCAP score of 6 points for the bumper test. The pedestrian performance of the optimized bumper system is validated by using a CAE (Computer Aided Engineering) analysis, which has been proven to be in accurate. A comparison between the test and analysis results is shown for the validation of accuracy. By using the optimized bumper system, the tests and development costs of a bumper can be reduced.     

Application of rack type motor driven power steering control system for heavy vehicles

The Electric Power Steering (EPS) or Motor Driven Power Steering (MDPS) mechanism proves to be a bright prospect among passenger vehicles ensuring better vehicle safety and fuel economy. The car manufacturers are focusing on the production of Rack type EPS system (REPS). This paper describes the development of concurrent simulation technique using TruckSim and control strategy for analysing RMDPS control system with a dynamic vehicle system. A full Truck vehicle model interacting with RMDPS control algorithm was concurrently simulated on a sinusoidal steering input. The dynamic responses of vehicle chassis and steering system resulting were evaluated and compared with proving ground experimental data. The comparisons show reasonable agreement on steering wheel torque, lateral acceleration and yaw rate. This concurrent simulation research leads the possibility of RMDPS performance evaluation of Truck and Semi-bonnet cars.