767 research outputs found
Applied methods and techniques for mechatronic systems: modelling, identification and control
No full textApplied Methods and Techniques for Mechatronic Systems brings together the relevant studies in mechatronic systems with the latest research from interdisciplinary theoretical studies, computational algorithm development and exemplary applications. Readers can easily tailor the techniques in this book to accommodate their ad hoc applications. The clear structure of each paper, background - motivation - quantitative development (equations) - case studies/illustration/tutorial (curve, table, etc.) is also helpful. It is mainly aimed at graduate students, professors and academic researchers in related fields, but it will also be helpful to engineers and scientists from industry. Lei Liu is a lecturer at Huazhong University of Science and Technology (HUST), China; Quanmin Zhu is a professor at University of the West of England, UK; Lei Cheng is an associate professor at Wuhan University of Science and Technology, China; Yongji Wang is a professor at HUST; Dongya Zhao is an associate professor at China University of Petroleum
<i>Supplementary material</i>
No full textSupplementary material belongs to article "Optimizing window size and directional parameters of GLCM texture featuresfor estimating rice AGB based on UAV multispectral imagery"(Jikai Liu, Yongji Zhu, Lijuan Song, Xiangxiang Su, Jun Li, Jing Zheng, Xueqing Zhu, Lantian Ren, Wenhui Wang, and Xinwei Li).</p
Multifactor Analysis of Landslide Mechanisms: A Case Study of Yongji Expressway, China
No full textBased on deformation monitoring and stability results obtained from geological mapping, geological drilling, macrolaboratory, and microlaboratory tests, the sliding mechanism of landslide in Guzhang County of Yongji expressway was studied. The bedding slope landslide results from cutting slope along the central white mud clay slip, and by on-site investigation and deep displacement monitoring, the clay is determined as the landslide surface. Combining the experimental results and similar geotechnical engineering experience, by back-calculation, the parameters of the soft interlayer are calculated as C(5 kPa) and ϕ (8.5°). Based on X-ray diffraction (XRD) and X-ray fluorescence spectroscopy (XRF) test, the results are concluded that the chlorite in clay interlayer is easily water softened, excavation slope after long-term heavy rainfall chlorite clay interlayer softening. Sustained rainfall and underground water levels showed a positive correlation when the slope is sliding, and the heavy rainfall continued to accelerate slope sliding. Furthermore, the slope surface displacement and profound displacement increase quickly, and rainfall and slope displacement also showed a positive correlation
Fundamentals in unsteady fluid fragmentation from drop impact
No full textThesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, February, 2021Cataloged from the official PDF of thesis.Includes bibliographical references (pages 517-527).Fluid fragmentation is ubiquitous in industrial, agricultural and natural settings. An important class of fragmentation processes is unsteady, continuously generating droplets of properties that vary over time. Yet, the dynamics of unsteady fragmentation has received little attention thus far. Common examples of unsteady fragmentation are splashes created upon drop impact on either a liquid pool or a solid surface. Upon impact, the drop is converted to a thin liquid sheet extending in the air and bounded by a thick rim. Hydrodynamic instabilities destabilize the rim: it develops corrugations that grow into ligaments which finally fragment into secondary droplets. Prior investigations of drop impacts have focused on the sheet dynamics but mostly overlooked its role on the final and most important outcome: secondary droplets and their formation. In this thesis, we study a two-dimensional unsteady fragmentation process upon drop impact on a small target.This allows us to explore the underlying fundamental physics of unsteady fragmentation. We develop experimental techniques and image processing algorithms that enable the quantification of the key unsteady physical quantities with high precision. We also establish a theoretical framework that links the dynamics of the sheet, rim, ligaments and secondary droplets, enabling the prediction of the secondary droplet statistics from the impact conditions only. We show that both the size and speed distributions of droplets ejected during the fragmentation are largely determined by the time-varying properties of the ligaments they originate from. The dynamics of the ligaments, rim and sheet are fully coupled. We show that the sheet evolution is influenced by the fluid shedding from the rim, causing mass and momentum loss, while ligament formation is controlled by both the fluid shedding and the rim deceleration, themselves governed by the sheet evolution.Using our proposed universal model of rim destabilization, we resolve this coupling and establish a closed theoretical framework that can predict the entire dynamics of the fragmentation. Our theoretical framework is fully validated by our experiments. These developments pave the way for a fundamental understanding of a wider range of unsteady fragmentation processes.by Yongji Wang.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Civil and Environmental Engineerin
Sliding mode control with self-turning law for uncertain nonlinear systems with time-delay and external disturbances
No full textThis study proposes a novel sliding mode control with self-turning law for nonlinear systems with time-delay and external disturbances possessing uncertain parameters. The adjustable control gain and a bipolar sigmoid function are online tuned to force the tracking error to approach zero. The proposed control scheme provides good transient and steady-state performance. Moreover as the proposed controller, the chatting phenomenon can be avoided and the problem of time-delay and external disturbances are solved for a class of nonlinear systems. The closed-loop control system stability is proved to use the Lyapunov method. Steady-state system performance and chattering are considerably improved. Numerical simulation results are given to illustrate the effectiveness of the proposed procedure. © Springer-Verlag Berlin Heidelberg 2014
Suboptimal mean controllers for bounded and dynamic stochastic distributions
No full textBased on the recently developed algorithms for the modelling and control of bounded dynamic stochastic systems (H. Wang, J. Zhang, Bounded stochastic distributions control for pseudo ARMAX stochastic systems, IEEE Transactions on Automatic control, 486-490), this paper presents the design of a subotpimal nonlinear mean controller for bounded dynamic stochastic systems with guaranteed stability. The B-spline functional expansion based square root model is used to represent the output probability density function of the system. This is then followed by the design of a mean controller of the output distribution of the system using nonlinear output tracking concept. A nonlinear quadratic optimization is performed using the well known Hamilton-Jacobi-Bellman equation. This leads to a controller which consists of a static unit, a state feedback part and an equivalent output feedback loop. In order to achieve high precision for the output tracking, the output feedback gain is determined by a learning process, where the Lyapunov stability analysis is performed to show the asymptotic stability of the closed loop system under some conditions. A simulation example is included to demonstrate the use of the algorithm and encouraging results have been obtained. © 2002 Elsevier Science Ltd. All rights reserved
Pattern recognition for MEMS images of surface topography using wavelets
No full textMicro-Electro-Mechanical Systems (MEMS) have been growing in interest in recent years. Due to the small size of the MEMS, the traditional method of metrology measurement seriously affects the parameter of the object being measured, and high accuracy metrology cannot be acquired. MEMS microstructure images of surface are most composed of a number of steps, grooves and slots. Pattern analysis and recognition of these microstructures with linear feature is one of the key problems in metrology and testing technology of Micro-Electro-Mechanical-System (MEMS). Effective detections of these components play an important role in simplifying feature model in pattern recognition and pattern match. Traditional Linear feature detectors based on pixel processing each by each may fail to detect out lines in image with low SNR. A fast discrete beamlet transform and a novel method of linear feature detection are proposed, which can detect lines with any orientation, location and length. Experiment results prove the efficiency of the method proposed even in image with very low SNR.</p
Regional Sustainable Development of Rural Areas Based on HDI - a case of Jilin Province, China
No full textThis paper introduces the connotation of Human Development Index (HDI) and its dimensional indices, as well as the HDI comprehensive evaluation method based on entropy weight. And the specific formula and steps for calculation are put forward. This paper also selects the HDI dimensional indices (life expectancy index, education index and GDP index), and constructs the evaluation index system of regional sustainable development. Based on the field investigation on Yushu, Jiutai and Yongji in Jilin Province, relevant data of HDI dimensional indices are collected. According to the comprehensive evaluation method based on entropy weight, sustainable development levels of the three typical rural areas in Jilin Province are evaluated. Result shows that the descending order of the sustainable development status of rural areas is Yongji, Jiutai and Yushu, indicating that the sustainable development levels are relatively backward. Educational levels of the three areas (counties) have a relatively large gap; and the quality of secondary education in rural areas remains to be improved. Ageing of population is growing in Jilin Province, and life expectancy of the three areas (counties) rises sharply. There are small differences among the national economic development of the three areas (counties) with the descending order of per capita GDP index being Yongji, Yushu and Jiutai. Based on this, relevant policy recommendations are put forward. Firstly, improve the continued investment in basic and secondary education in rural areas with practical measures. Secondly, strengthen the rural health care and welfare protection in rural areas in order to improve the living standard of rural residents. Thirdly, while maintaining rapid economic growth, we should pay attention to the population factors and strive to the steady growth of per capita economic level
Regional Sustainable Development of Rural Areas Based on HDI - a case of Jilin Province, China
No full textThis paper introduces the connotation of Human Development Index (HDI) and its dimensional indices, as well as the HDI comprehensive evaluation method based on entropy weight. And the specific formula and steps for calculation are put forward. This paper also selects the HDI dimensional indices (life expectancy index, education index and GDP index), and constructs the evaluation index system of regional sustainable development. Based on the field investigation on Yushu, Jiutai and Yongji in Jilin Province, relevant data of HDI dimensional indices are collected. According to the comprehensive evaluation method based on entropy weight, sustainable development levels of the three typical rural areas in Jilin Province are evaluated. Result shows that the descending order of the sustainable development status of rural areas is Yongji, Jiutai and Yushu, indicating that the sustainable development levels are relatively backward. Educational levels of the three areas (counties) have a relatively large gap; and the quality of secondary education in rural areas remains to be improved. Ageing of population is growing in Jilin Province, and life expectancy of the three areas (counties) rises sharply. There are small differences among the national economic development of the three areas (counties) with the descending order of per capita GDP index being Yongji, Yushu and Jiutai. Based on this, relevant policy recommendations are put forward. Firstly, improve the continued investment in basic and secondary education in rural areas with practical measures. Secondly, strengthen the rural health care and welfare protection in rural areas in order to improve the living standard of rural residents. Thirdly, while maintaining rapid economic growth, we should pay attention to the population factors and strive to the steady growth of per capita economic level.Human development index (HDI), Rural area, Sustainable development, Entropy weight, China, Community/Rural/Urban Development, Research Methods/ Statistical Methods, Resource /Energy Economics and Policy,
- …
