Beijing, China
Beijing, China

Tsinghua University is a research university located in Beijing, People's Republic of China , and is one of the nine members in the C9 League. The institution was originally established in 1911 under the name "Tsinghua College" and had been renamed several times since then: from "Tsinghua School" which was used one year after its establishment, to "National Tsinghua University" which was adopted three years after the foundation of its university section in 1925. With its motto of Self-Discipline and Social Commitment, Tsinghua University describes itself as being dedicated to academic excellence, the well-being of Chinese society and to global development. It has consistently received top rankings in both domestic and international university rankings, alongside Peking University, which is the top elite higher learning institution in the mainland People's Republic of China .Tsinghua University in the People's Republic of China is a separate institution from the Taiwanese National Tsing Hua University located in Hsinchu city in the high-tech democratic industrialized developed country of the Republic of China . After the Chinese Civil War and the subsequent split of China into the two present-day separate sovereign independent countries of the Republic of China and the People's Republic of China , some academics and staff from the original Tsinghua University in the mainland People's Republic of China left and created the National Tsing Hua Institute of Nuclear Technology in 1955 in Hsinchu, Republic of China , which later became the National Tsing Hua University of island nation of Taiwan.The two Tsinghua universities are not affiliated with each other, but both claim to be successors of the original Tsinghua University. As a result of this dispute, the universities claimed to be the rightful recipient of the funds from the Boxer Rebellion indemnity that was used to start Tsinghua University. This indemnity was transferred to the university in Taiwan after the democratic Republic of China retreated to the island of Taiwan following the invasions and take over of mainland China by the communist People's Republic of China . Wikipedia.

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Zhou H.,Beijing University of Technology | Shi G.,Tsinghua University | Wang Y.,Tsinghua University | Chen H.,Beijing University of Technology | De Roeck G.,Catholic University of Leuven
Journal of Constructional Steel Research | Year: 2016

An enhanced fatigue assessment of critical welded details in a steel-concrete composite railway bridge was carried out by fatigue crack propagation analysis based on linear elastic fracture mechanics (LEFM). The most fatigue critical connections concerned in this study were identified by the preliminary fatigue assessment based on the S-N method in the previous research of the authors Zhou et al. (2013). Three-dimensional crack models of the critical connections were incorporated into the global-local finite element model of the bridge. The stress intensity factor (SIF) histories of the cracks were calculated through dynamic analysis of the bridge due to the high-speed train passages, which validated the applicability and the accuracy of the empirical SIF formulas for the concerned bridge details. The fatigue crack growth curve, represented by crack size versus number of train passages, was obtained through crack propagation analysis based on the Paris law and LEFM, and fatigue propagation life was predicted for each critical connection. The proposed crack propagation analysis method provides a general and alternative approach to evaluate the fatigue life of welded details in steel bridges. © 2016 Elsevier Ltd. All rights reserved.

Document Keywords (matching the query): railroad cars, crack propagation analysis.

Ahmed W.,Tsinghua University | Wu Y.W.,Tsinghua University
Journal of Computer and System Sciences | Year: 2013

Software's reliability in distributed systems has always been a major concern for all stake holders especially for application's vendors and its users. Various models have been produced to assess or predict reliability of large scale distributed applications including e-government, e-commerce, multimedia services, and end-to-end automotive solutions, but reliability issues with these systems still exists. Ensuring distributed system's reliability in turns requires examining reliability of each individual component or factors involved in enterprise distributed applications before predicting or assessing reliability of whole system, and Implementing transparent fault detection and fault recovery scheme to provide seamless interaction to end users. For this reason we have analyzed in detail existing reliability methodologies from viewpoint of examining reliability of individual component and explained why we still need a comprehensive reliability model for applications running in distributed system. In this paper we have described detailed technical overview of research done in recent years in analyzing and predicting reliability of large scale distributed applications in four parts. We first described some pragmatic requirements for highly reliable systems and highlighted significance and various issues of reliability in different computing environment such as Cloud Computing, Grid Computing, and Service Oriented Architecture. Then we elucidated certain possible factors and various challenges that are nontrivial for highly reliable distributed systems, including fault detection, recovery and removal through testing or various replication techniques. Later we scrutinize various research models which synthesize significant solutions to tackle possible factors and various challenges in predicting as well as measuring reliability of software applications in distributed systems. At the end of this paper we have discussed limitations of existing models and proposed future work for predicting and analyzing reliability of distributed applications in real environment in the light of our analysis. © 2013 Elsevier Inc.

Document Keywords (matching the query): reliability analysis.

Ma C.,Tsinghua University | Hu J.,Tsinghua University | Zhang J.,Tsinghua University | Huang S.,Tsinghua University
Qinghua Daxue Xuebao/Journal of Tsinghua University | Year: 2010

The sub-structure method plays an important role in occupant restraint system optimization design in automotive side impact. This paper analyzed restraint system optimization using the sub-structure method for side impacts. The finite element model for the entire vehicle and the sub-structure for the side impact were developed using the software PAM-CRASH. Analysis of the predicted dummy responses of the entire vehicle and the sub-structure model with different occupant restraint system parameters shows that the sub-structure method is suitable for optimization of the bolster, door trim, and door shapes. This study provides a reference for the application of the sub-structure method for side impact simulations.

Document Keywords (matching the query): automotive safety.

Gao P.,Yanshan University | Du Y.,Tsinghua University | Wang Y.,Tsinghua University
Conference Proceedings of the Society for Experimental Mechanics Series | Year: 2015

Disc brake squeal remains an elusive problem in the automotive industry and developing a model that will predict unstable squeal-noise dynamics with reasonable accuracy is in urgent need. In this paper, a two stage validation method of closed-loop coupling disc brake model for squeal analysis using complex eigenvalue analysis is presented. At component level, finite element (FE) models are verified through the comparison of FE calculation and modal test results. At the system level, optimization method is adopted. Experiment modal analysis of stationary disc brake system with brake line pressure and brake torques applied is conducted. Then an optimization process is initiated to minimize the differences between modal frequencies predicted by the stationary model and those from test. Thus model parameters more close to real situation are found. Unstable mode prediction results of validated model are compared with those from brake noise bench test. The validated model can predict most of the squeal frequencies and the real part represent the occurrences of squeal. The method presented in this paper is proven to be valid and effective. © The Society for Experimental Mechanics, Inc. 2015.

Document Keywords (matching the query): automotive industry, modal analysis, experiment modal analysis, complex eigenvalue analysis.

Shi J.,Tsinghua University | Bai Y.,Tsinghua University | Tao L.,Tsinghua University | Atchley P.,University of Kansas
Accident Analysis and Prevention | Year: 2011

A major, but unstudied, cause of crashes in China is drivers that "scramble" to gain the right of way in violation of traffic regulations. The motivation of this study is to explore the features of drivers' scrambling behaviors and the attitudes and driving skills that influence them. In this study, we established a scrambling behavior scale, and developed a driving attitude scale and a driving skill scale using factor analysis of an Internet survey of 486 drivers in Beijing. A structural equation model of scrambling behavior toward cars and pedestrians/cyclists was developed with attitudes and skills as predictors of behavior. Skills and attitudes of approval toward violations of traffic rules did not predict scrambling behaviors, while the motivation for safety and attitudes against violating traffic rules led to reduced scrambling behaviors. The current work highlights this peculiar aspect of Chinese roads and suggests methods to reduce the behavior. © 2011 Elsevier Ltd.

Document Keywords (matching the query): car driving, factor analysis, factor analysis statistical, automobile driving, factorial analysis.

Eben Li S.,Tsinghua University | Li K.,Tsinghua University | Wang J.,Tsinghua University
Vehicle System Dynamics | Year: 2013

A recent design issue of adaptive cruise control systems is how to reduce fuel consumption when following a preceding vehicle. High fuel economy is achievable through reducing acceleration level, however, it is also significantly restrained by two other functional demands, track capability and driver desired response. In the framework of multi-objective coordination, this paper develops and experimentally validates an economy-oriented headway control algorithm for a passenger car with internal combustion engine. The control algorithm is synthesised in a hierarchical structure. The upper controller, undertaking a major coordinating task, is designed based on the model predictive control theory. Fuel economy, tracking capability, and the driver desired response are formulated as its cost function and constraints in a finite prediction horizon. As further analysis indicated, such a design inevitably results in infeasible control inputs in some extreme cases, e.g. urgent situations involving rapid acceleration/deceleration. A constraint softening method is adopted to enlarge the feasible region in the cost of somewhat sacrificing the optimality of the original cost function. Finally, a prototyping controller is developed based on xPC toolbox and equipped in a passenger car. The followed field tests show that, compared to a linear quadratic controller, such an algorithm improves both fuel economy and tracking capability while also being more responsive to driver car-following behaviours. © 2013 Copyright Taylor and Francis Group, LLC.

Document Keywords (matching the query): automobiles, predictive control systems, model predictive control, car following.

Liu C.,Tsinghua University | Gray A.,University of California at Berkeley | Lee C.,University of California at Berkeley | Hedrick J.K.,University of California at Berkeley | Pan J.,Tsinghua University
Proceedings of the American Control Conference | Year: 2014

This paper presents a novel predictive control approach based on the unscented transformation with recursive feasibility analysis and an experimental validation for lane keeping of semi-autonomous vehicles. The optimization problem to be solved is nonlinear with stochastic disturbances and probability constraints on states. The unscented transformation is utilized to calculate the propagation of disturbed states over the prediction horizon, and the probability constraints are transformed into constraint functions with Chebyshev's inequality. A sufficient condition for recursive feasibility is proved by considering the worst case of the disturbance realization. Experiments on the lane keeping system with an uncertain driver model validate the effectiveness of the proposed approach. © 2014 American Automatic Control Council.

Document Keywords (matching the query): automotive, predictive control, predictive control for nonlinear systems.

Song H.,Tsinghua University | Wang H.,Tsinghua University
EVS 2010 - Sustainable Mobility Revolution: 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium and Exhibition | Year: 2010

During the history of the automotive development, there are two key factors, which have the significant impact on the fuel consumption. First of all, vehicle technologies influence the fuel efficiency directly. Secondly, the market shares restrict the overall average vehicle fuel consumption. China is being in rapid development both automotive technology and vehicle market. Under such situation, the technology and market share will be changing continuously. In a certain extent, China is likely undergoing the pattern of U.S. 20 years ago, who is promulgating the regulations and policies. Lesson learned from U.S vehicles' history of fuel consumption, which focus on the change trends as well as the impact factors using statistical analysis and DIVASA method, the paper studies and optimizes the development of China's automotive technology pattern, meanwhile, predicts the development of automobile fuel consumption. In addition, the paper also suggests some recommendations that would decrease the fuel consumption from China's passenger vehicles in the coming years.

Document Keywords (matching the query): automotive technology, automotive development.

Wang L.R.,CAS Shenzhen Institutes of Advanced Technology | Lu Z.H.,Tsinghua University | Hagiwara I.,Tokyo Institute of Technology
International Journal of Automotive Technology | Year: 2010

Hydraulically damped rubber mount (HDM) can effectively attenuate vibrations transmitted between an automotive powertrain and body/chassis and reduce interior noise in the car compartment. Predicting the dynamic characteristics of a HDM faces challenges due to fluid-structure interactions between the rubber spring and fluid in the chambers, nonlinear material properties of the rubber parts and turbulent flow in the chambers and fluid track linking chambers. In this paper, an experimental analysis and hydrostatic finite element (FE) modeling technique are integrated in a numerical simulation approach to modeling the dynamic characteristics of a HDM with a lumped-parameter HDM model. The dynamic characteristics of a typical HDM with a fixed decoupler are predicted and compared with experimental results, which verify the effectiveness of the proposed approach. Moreover, a parametric effect analysis is performed to demonstrate parameter influence on dynamic characteristic, which provides a concise design guideline for the parameter adjustments necessary for a HDM to meet the vibration isolation requirements of a powertrain mount system. © 2010 The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg.

Document Keywords (matching the query): automobile parts and equipment, finite element analysis, experimental analysis, vibration analysis, dynamic analysis.

PubMed | HIGH-TECH, Tsinghua University and Suzhou INVO Automotive Electronics Co.
Type: Journal Article | Journal: Sensors (Basel, Switzerland) | Year: 2014

Preceding vehicle detection and tracking at nighttime are challenging problems due to the disturbance of other extraneous illuminant sources coexisting with the vehicle lights. To improve the detection accuracy and robustness of vehicle detection, a novel method for vehicle detection and tracking at nighttime is proposed in this paper. The characteristics of taillights in the gray level are applied to determine the lower boundary of the threshold for taillights segmentation, and the optimal threshold for taillight segmentation is calculated using the OTSU algorithm between the lower boundary and the highest grayscale of the region of interest. The candidate taillight pairs are extracted based on the similarity between left and right taillights, and the non-vehicle taillight pairs are removed based on the relevance analysis of vehicle location between frames. To reduce the false negative rate of vehicle detection, a vehicle tracking method based on taillights estimation is applied. The taillight spot candidate is sought in the region predicted by Kalman filtering, and the disturbed taillight is estimated based on the symmetry and location of the other taillight of the same vehicle. Vehicle tracking is completed after estimating its location according to the two taillight spots. The results of experiments on a vehicle platform indicate that the proposed method could detect vehicles quickly, correctly and robustly in the actual traffic environments with illumination variation.

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