Study of a hybrid modular exhaust turbocharging system and its application on an 8-cylinder marine diesel engine

Journal of Mechanical Science and Technology - For turbocharging engines, the structure of the exhaust system directly affects the flow and energy transfer process of the exhaust gas, which has a...     

轿车车门关闭力自动测试评价系统开发

应用力与位移传感器和计算机技术,研制了轿车车门关闭力一位移自动测量系统。该系统能够同时采集关门过程中车门的关门力和位移。实测结果表明,该测量系统结构简单、操作方便,测量精度满足实际要求。     

A novel approach for the prediction of bend allowance in air bending and comparison with other methods

Air-bending is a major sheet-metal forming operation, where precise prediction of the developed shape is a key factor for the accuracy assessment of the final shape for the part after bending. To predict the blank shape, accurate estimation of the bend-allowance (BA) is necessary, which can be defined as the length of the un-stretched fiber at the bent state of shape. There are several different approaches to find the BA values depending on either experience-based or knowledge-based techniques. In this paper, a brief summary is provided for different approaches to find the BA values by comparing their advantages as well as, their drawbacks. They are evaluated in terms of accuracy, efficiency and ease of implementation for integrated CAD/CAM environment. Then, a novel approach; by using higher order response surface (RS) fitting for the prediction of BA during air-bending is demonstrated. This technique is in general found very promising as an integrated tool for both CAD interfaces, as well as CNC machine tools. The RS predictions, which are generated from over 1,000 bending experiments using combinations of bending radius, bending angle and material thickness, are built for different orders and are compared to Artificial Neural Network (ANN) models that are also trained by using the same experimental data.     

Nonlinear system identification of automotive dampers: A time and frequency-domain analysis

This paper provides an overview of a number of nonlinear system identification methods as applied to the analysis of nonlinear automotive dampers. The motivation for illustrating a number of approaches is that each method provides different insights into the behavior of the systems and therefore the methods are complementary. The background for each of the methods is given and each is demonstrated through an experimental case study.     

Effects of gap between impeller and volute tongue on a pressure fluctuation in double-suction pump

Journal of Mechanical Science and Technology - The pump is a machine that receives power through a rotating shaft and converts the mechanical energy into pressure and kinetic energy of fluid....     

A software-based measurement system for testing and analysis of automotive brake squeal

A software-based measurement system using both analogue data acquisition and digital communication via a general-purpose interface bus (GPIB) board has been developed for analysis and evaluation of disc brake squeal. The system is built around a computer and based on commercial software. Brake pressure and torque, rotational speed, five different temperatures, and sound emission are logged once a second. If the sound is characterised as a squeal it is saved to file together with the other parameters. The measurement system is very flexible, allowing for different types of instruments and sensors to be used by adapting the software. Furthermore, the same software is used for evaluation of the collected data. Mechanically, the equipment consists of a complete front wheel suspension where the original brake disc and caliper are mounted in a steel tube chassis. The brake disc is driven by a DC electric motor, while a hydraulic system provides the brake pressure. Brake pressure and rotational speed can be controlled independently.     

A novel shape-based coding-decoding technique for an industrial visual inspection system

This paper describes a unique single camera-based dimension storage method for image-based measurement. The system has been designed and implemented in one of the integrated steel plants of India. The purpose of the system is to encode the frontal cross-sectional area of an ingot. The encoded data will be stored in a database to facilitate the future manufacturing diagnostic process. The compression efficiency and reconstruction error of the lossy encoding technique have been reported and found to be quite encouraging.     

A new algorithm and multi-response Taguchi method to solve line balancing problem in an automotive industry

One of the most important issues in an assembly line balancing problem is to control a flow of production and manufacturing to provide continuous flow to balance the production line. For this purpose, a line balancing problem was considered for a special assembly line in an automotive factory. A new algorithm was required to deal with balancing an assembly line which consisted of the same job which must be performed by more than one worker at the same time. In this way, the new algorithm was expected to be effective in such a case that jobs were simultaneously completed in a parallel way. In order to measure effectiveness of the proposed algorithm, performance criteria were identified as total number of assembly station, total number of workers, and line productivity. As a result of the application of the proposed algorithm with taking into consideration factors such as cycle time, an allowable number of workers in an assembly station, and an allowable idle time of a worker, alternative solutions were determined in order to measure these criteria. However, these alternative solutions do not give any information about which of the solutions provide not only minimization of the number of assembly station and number of workers on the line but also maximize the line productivity at the same time. Hereby, a multi-response Taguchi method was applied in order to investigate levels of factors which directly affected system performance criteria.     

A numerical study on the effect of the flow control using bleeding systems in a bump-type inlet

In many supersonic inlets, several oblique shock waves are followed by a terminal normal shock wave. The normal shock-wave/turbulent boundary-layer interaction is critical with respect to its influence on the development of boundary layer throughout the subsonic diffuser and the total pressure recovery at the engine face. In the current study, the bump-type inlet was designed for two oblique shock waves and a normal shock wave. In addition, a porous surface was installed underneath the root of the normal shock wave. The effect of flow control on the interaction between the normal shock wave and turbulent boundary layer in supersonic inlets by using the bleeding system was investigated numerically and was evaluated with respect to the inlet performance parameters.

     

A novel nanofluid manufacturing process using a cylindrical flow cooling method in an induction heating system

The main purpose of this study is to develop a cylindrical flow cooling method in an induction heating system that is capable of producing the nanofluid. The system consists of a high frequency induction heating system, vacuum system, temperature control system, and a cylindrical curtain collector. The raw material Zn is evaporated by the high frequency induction heating system. The gas phase Zn is condensed and collected by a water cylindrical curtain collector. During the process, the gas phase Zn is oxidized. The ZnO nanoparticles were collected and suspended in de-ionized water. Through transmission electron microscopy (TEM), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and particle size analyzer (PSA), a set of applicable parameters size can be obtained. Results show that the lower the collecting liquid temperature and the shorter the collecting distance, the smaller the nanoparticle size obtained. An aspect of UV/V is absorbency, the produced ZnO nanofluid absorbed UV when the wavelength is 360 nm to 380 nm.     

An efficient method to predict the heat transfer performance of a louver fin radiator in an automotive power system

A numerical method to efficiently predict heat transfer phenomena of a louver fin radiator was presented — multi-scale semimicroscopic heat exchange (SHE) method. This method consists of microscopic analysis and semimicroscopic analysis. To predict heat transfer characteristics of a louver fin element, the microscopic analysis employs modeling of the detailed geometry of a fin element. Numerical models for the heat transfer rate and flow friction derived from the microscopic analysis are then used for simulations of the full radiator model in semimicroscopic analysis. In the semimicroscopic analysis, conjugate heat transfer is analyzed for the domain with the radiator whose louver fin area is replaced by a porous media. The results with the proposed method show a good agreement with the experimental data. The proposed method can be used to predict flow and heat transfer characteristics of a realistic louver fin radiator with a reduced cost and sufficient accuracy.     

A numerical study on the unsteady flow behavior and the performance of an automotive sirocco fan

An automotive sirocco fan has been widely used in air-conditioning devices. It is essential to understand the flow characteristics of an automotive sirocco fan to satisfy the trends for more efficient and less noise. In this study, numerical calculations were conducted to explain the three-dimensional unsteady, incompressible flow characteristics and performance of the sirocco fan using FLUENT. Reynolds-averaged Navier-Stokes equations with the standard k - ɛ turbulence model were used for the numerical analysis. The sliding mesh was used to simulate the relative transient motion of impeller against scroll. It was found that the inactive zone and the secondary flow reduce efficiency because they cause internal losses. A parametric study was performed to improve efficiency of the sirocco fan, using two geometric variables. Reducing the width of impeller could decrease the relative size of inactive zone and secondary flow. Changing the position of cut-off had little influence on the efficiency. Thus an improvement of efficiency could be achieved by reducing the width of impeller. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.     

An exploration of green supply chain practices and performances in an automotive industry

During recent years, the natural environment has become a challenging topic that business organizations must consider due to the economic and ecological impacts and increasing awareness of environment protection. Globalization and the increased number of countries entering the World Trade Organization (WTO) have promoted green supply chain management (GSCM) practices in manufacturing organizations. GSCM has emerged as an important organizational philosophy and a proactive approach to reduce environmental risks. Increasing pressures such as stricter regulations, increased community, and consumer pressures, and the developing country’s aim to enter the WTO have caused automotive supply chain managers to consider and to implement GSCM practices to improve both their economic and environmental performances. This paper explores the practices and performances of the GSCM based on the GSCM literature, and it considers the relationship between green supply chain practices (initiatives) and performance outcomes. In this paper, two questionnaires were developed and a survey conducted to assess the importance of GSCM practices and performances in an automotive company in a developing country using a fuzzy multiple criteria decision-making method. The result of this paper presents practical guidance for managers in performing GSCM practices by ranking GSCM practices according to their importance which leads to improving GSCM performances.     

A DMA interface between a Biomation 8100 and an Intel MDS-800 microcomputer development system

An interface is described which permits high-speed data transfer between a Biomation 8100 transient recorder and an Intel MDS-800 microcomputer system equipped with an MDS-501 DMA (direct memory access) channel controller. The interface is especially useful for data acquisition situations in which many successive traces must be recorded. For example, signal averaging can be performed within the microcomputer system.     

一种新型高性能价格比数控系统

介绍了当前工业发达国家数控技术的研究方向和我国数控技术发展的现状,提出了一种新型高性能价格比的数控系统,并介绍了该系统的原理与结构,为国内研究数控技术提出了一条新途径。     

Application of a data-driven monitoring technique to diagnose air leaks in an automotive diesel engine: A case study

This paper presents a case study of the application of a data-driven monitoring technique to diagnose air leaks in an automotive diesel engine. Using measurement signals taken from the sensors/actuators which are present in a modern automotive vehicle, a data-driven diagnostic model is built for condition monitoring purposes. Detailed investigations have shown that measured signals taken from the experimental test-bed often contain redundant information and noise due to the nature of the process. In order to deliver a clear interpretation of these measured signals, they therefore need to undergo a ‘compression’ and an ‘extraction’ stage in the modelling process. It is at this stage that the proposed data-driven monitoring technique plays a significant role by taking only the important information of the original measured signals for fault diagnosis purposes. The status of the engine's performance is then monitored using this diagnostic model. This condition monitoring process involves two separate stages of fault detection and root-cause diagnosis.The effectiveness of this diagnostic model was validated using an experimental automotive 1.9 L four-cylinder diesel engine embedded in a chassis dynamometer in an engine test-bed. Two joint diagnostics plots were used to provide an accurate and sensitive fault detection process. Using the proposed model, small air leaks in the inlet manifold plenum chamber with a diameter size of 2–6 mm were accurately detected. Further analyses using contribution to T² and Q statistics show the effect of these air leaks on fuel consumption. It was later discovered that these air leaks may contribute to emissions fault.In comparison to the existing model-based approaches, the proposed method has several benefits: (i) it makes no simplifying assumptions, as the model is built entirely from the measured signals; (ii) it is simple and straight-forward; (iii) there is no additional hardware required for modelling; (iv) it is a time and cost-efficient way to deliver condition monitoring (i.e. fault diagnosis application); (v) it is capable of pin-pointing the root-cause and the effect of the problem; and (vi) it is feasible to be implemented in practice.     

一种新的可变窗长的FMT同步算法

在FMT(Filtered Multitone)系统中,为实现同步需要构造训练序列,但由于原型滤波滤波器长度远大于子载波数,导致训l练序列周期过长,训练符号数过多,同步位置的确定存在模糊性,而且载波频偏估计范围过小.为了克服以上缺陷,提出了一种新的可变窗长FMT同步算法,通过调节同步窗口大小调整载波频偏捕获范围,该算法可以精确确定同步位置,并且训练序列只需要一个FMT符号.     

考虑产品服务组合效应的产品服务系统方案评价方法

针对由产品和服务模块组成的产品服务系统方案评价问题,考虑到传统多属性决策方法难以处理产品和服务的组合效应,研究了一种融合模块评价和模块组合效应评价的产品服务系统方案评价方法。采用二元语义表达模型处理专家不确定性评价信息,提出多粒度二元语义评价信息统一方法,考虑专家的客观权重获取方案模块的集成评价值,结合模块的主客观权重计算产品服务系统方案的初始评价值;通过获取产品模块和服务模块间的组合效应矩阵信息,修正产品服务系统方案的初始评价值。以某企业挖掘机PSS配置方案评价为例,验证了所提方法的有效性。     

A novel disturbance-observer based friction compensation scheme for ball and plate system

Friction is often ignored when designing a controller for the ball and plate system, which can lead to steady-error and stick-slip phenomena, especially for the small amplitude command. It is difficult to achieve high-precision control performance for the ball and plate system because of its friction. A novel reference compensation strategy is presented to attenuate the aftereffects caused by the friction. To realize this strategy, a linear control law is proposed based on a reduced-order observer. Neither the accurate friction model nor the estimation of specific characteristic parameters is needed in this design. Moreover, the describing function method illustrates that the limit cycle can be avoided. Finally, the comparative mathematical simulations and the practical experiments are used to validate the effectiveness of the proposed method.