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Safe Arm Using Compliant Hybrid Joints for Mobile Manipulators in Human-Symbiotic Environments
Zhijun Li,Aiguo Ming,Ning Xi,Jiangong Gu,Makoto Shimojo 한국과학기술원 인간친화 복지 로봇 시스템 연구센터 2005 International Journal of Assistive Robotics and Me Vol.6 No.1
In this paper, a safe arm with compliant hybrid joints for human-friendly service robots is presented, which realizes human safety, absorbing impact force, and task fulfillment. The robot is composed of links covered with soft materials and hybrid joints, which can be put into active or passive mode as needed. In an unexpected or expected collision with human, the arising impulse force is attenuated effectively by the physical model, which is developed with hybrid joints and soft covering. Owing to the displacement of the links when the joint is passive, a recovery control algorithm has been developed for the end-effector to maintain its desired task position after the collision. The force attenuation property has been verified through collision experiments in that the capability of the proposed passive arm in overcoming the limitations of active compliance control has been demonstrated. Simulation results also showed that the proposed control method is useful for robot"s task fulfillment as well.
Hyperspectral Image Classification based on Co-training
Zhijun Zheng,Yanbin Peng 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.12
The abundant information available in hyperspectral image has provided important opportunities for land-cover classification and recognition. However, “Curse of dimensionality” and small training sample set are two difficulties which hinder the improvement of computational efficiency and classification precision. In this paper, we present a co-training based method on hyperspectral image classification. Firstly, two views of samples are generated through two kinds of dimensionality reduction methods. After that, the co-training process is viewed as combinative label propagation over two independent views. Experimental results on real hyperspectral image show that the proposed method has better performance than the other state-of-the-art methods.
Top-emitting organic light-emitting devices based on silicon substrate using Delta -doping technique
Zhijun Wu,Hengqun Guo,Jiaxian Wang 한국물리학회 2011 Current Applied Physics Vol.11 No.2
We have fabricated a Top-emitting organic light-emitting device on silicon substrate Delta -doping technique. Using ultrathin quinacridone as emitting layer, the performance of Top-emitting organic lightemitting device is improved obviously. However, when increasing the thickness of the anode, the performance of device is enhanced dramatically. The max power efficiency of device is 5.9 Lm/W at 5 V corresponding to the current efficiency of 9.3 cd/A. The max current efficiency of device is also increases to 11 cd/A at 7 V.
Two-stage layoutesize optimization method for prow stiffeners
Zhijun Liu,Shingo Cho,Akihiro Takezawa,Xiaopeng Zhang,Mitsuru Kitamura 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1
Designing sophisticate ship structures that satisfy several design criteria simultaneously with minimum weight and cost is an important engineering issue. For a ship structure composed of a shell and stiffeners, this issue is more serious because their mutual effect has to be addressed. In this study, a two-stage optimization method is proposed for the conceptual design of stiffeners in a ship's prow. In the first stage, a topology optimization method is used to determine a potential stiffener distribution based on the optimal results, whereupon stiffeners are constructed according to stiffener generative theory and the material distribution. In the second stage, size optimization is conducted to optimize the plate and stiffener sections simultaneously based on a parametric model. A final analysis model of the ship-prow structure is presented to assess the validity of this method. The analysis results show that the two-stage optimization method is effective for stiffener conceptual design, which provides a reference for designing actual stiffeners for ship hulls.
The structured multiparameter eigenvalue problems in finite element model updating problems
Zhijun Wang,Bo Dong,Yan Yu,Xinzhu Zhao,Yizhou Fang 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.5
The multiparameter eigenvalue method can be used to solve the damped finite element model updating problems. This method transforms the original problems into multiparameter eigenvalue problems. Comparing with the numerical methods based on various optimization methods, a big advantage of this method is that it can provide all possible choices of physical parameters. However, when solving the transformed singular multiparameter eigenvalue problem, the proposed method based on the generalised inverse of a singular matrix has some computational challenges and may fail. In this paper, more details on the transformation from the dynamic model updating problem to the multiparameter eigenvalue problem are presented and the structure of the transformed problem is also exposed. Based on this structure, the rigorous mathematical deduction gives the upper bound of the number of possible choices of the physical parameters, which confirms the singularity of the transformed multiparameter eigenvalue problem. More importantly, we present a row and column compression method to overcome the defect of the proposed numerical method based on the generalised inverse of a singular matrix. Also, two numerical experiments are presented to validate the feasibility and effectiveness of our method.
EXISTENCE OF PERIODIC SOLUTION OF SOME ECO-EPIDEMIOLOGICAL SYSTEMS
Zhijun Liu,Sahabuddin Sarwardi 한국전산응용수학회 2010 Journal of applied mathematics & informatics Vol.28 No.5
The effect of impulse in the ecological models makes them more realistic. Recently, the eco-epidemiological models have become an important field of study from the both mathematical and ecological view points. In this article, we consider some eco-epidemiological systems under the influence of impulsive force. A set of sufficient conditions for the permanence of the system are derived. Stability of the trivial solution and at least one strictly positive periodic solution are obtained. Numerical examples are given in support to our analytical findings. Finally, a short discussion concludes the paper.
An Efficient Framework for Computation Offloading In Mobile Cloud Computing
Zhijun Zhang,HyoTaek Lim,Hoon Jae Lee 한국정보통신학회 2014 2016 INTERNATIONAL CONFERENCE Vol.6 No.1
With the emergence of mobile cloud computing (MCC), Mobile applications are becoming increasingly, there is a significant increase of mobile subscriptions, the drives need a strong demand for mobile cloud applications and services for mobile device users. However, mobile terminals are resource-constrained and therefore, running these applications directly on it is not satisfactory given a user’s expectations. This paper proposes a novel offloading service that can seamlessly offload some of the tasks of a mobile application from mobile terminals to cloud. Offloading computation to the cloud effectively expands the usability of mobile terminals beyond their physical limits, and also greatly extends their battery charging intervals through potential energy savings. The system architecture and key components of the proposed offloading service are presented, prototyped, and evaluated. The results of experiments and simulations have demonstrated the effectiveness and efficiency of this offloading service for mobile applications.