Lei Liu

Publications

2 GPI Observer-based Tracking Control and Synchronization of Chaotic Systems

Authors: Yongji Wang, Lei Liu, Dangjun Zhao

Abstract:

Based on general proportional integral (GPI) observers and sliding mode control technique, a robust control method is proposed for the master-slave synchronization of chaotic systems in the presence of parameter uncertainty and with partially measurable output signal. By using GPI observer, the master dynamics are reconstructed by the observations from a measurable output under the differential algebraic framework. Driven by the signals provided by GPI observer, a sliding mode control technique is used for the tracking control and synchronization of the master-slave dynamics. The convincing numerical results reveal the proposed method is effective, and successfully accommodate the system uncertainties, disturbances, and noisy corruptions.

Keywords: Chaotic systems, Sliding Mode Control, GPI observer, master-slave synchronization

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1 Reentry Trajectory Optimization Based on Differential Evolution

Authors: Songtao Chang, Yongji Wang, Lei Liu, Dangjun Zhao

Abstract:

Reentry trajectory optimization is a multi-constraints optimal control problem which is hard to solve. To tackle it, we proposed a new algorithm named CDEN(Constrained Differential Evolution Newton-Raphson Algorithm) based on Differential Evolution( DE) and Newton-Raphson.We transform the infinite dimensional optimal control problem to parameter optimization which is finite dimensional by discretize control parameter. In order to simplify the problem, we figure out the control parameter-s scope by process constraints. To handle constraints, we proposed a parameterless constraints handle process. Through comprehensive analyze the problem, we use a new algorithm integrated by DE and Newton-Raphson to solve it. It is validated by a reentry vehicle X-33, simulation results indicated that the algorithm is effective and robust.

Keywords: Differential Evolution, Trajectory Optimization, reentry vehicle, constraint optimal

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Abstracts

3 Multi-Criteria Decision-Making Evaluations for Oily Waste Management of Marine Oil Spill

Authors: Lei Liu, Naznin Sultana Daisy, Mohammad Hesam Hafezi

Abstract:

Nowadays, oily solid waste management has become an important issue for many countries due to frequent oil spill accidents and the increase of industrial oily wastewater. The historical oil spill data show that marine oil spills that affect the shoreline can, in extreme cases, produce up to 30 or 40 times more waste than the volume of oil initially released. Hence, responsive authorities aim to develop the most effective oily waste management solution in a timely manner to manage and minimize the waste generated. In this study initially, we tried to develop the roadmap of oily waste management for three-tiered spill scenarios for Atlantic Canada. For that purpose, three oily waste disposal scenarios are evaluated via six criteria which are determined according to the opinions of the experts from the field. Consequently, through sustainable response strategies, the most appropriate and feasible scenario is determined. The results of this study will assist to develop an integrated oily waste management system for identifying the optimal waste-generation-allocation-disposal schemes and generating the optimal management alternatives based on the holistic consideration of environmental, technological, economic, social, and regulatory factors.

Keywords: multi-criteria decision making, oil spill response, oily waste management, marine oil spill

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2 The Rocketing Raise of Bride Price in the Rural China: Intimacy and Family Changes Brought by Rural Urban Migration

Authors: Lei Liu

Abstract:

This paper concerns on a special phenomenon of rocketing of bride’s price in rural China after the rural-urban labor migration nowadays. It provides a brief overview of three major prospective on marriage exchange, especially impose the local marriage market due to the post-migration economic environments. Then the author highlights on several factors that influence the rocketing raise of rural marriage gifts using both the primary data from census 2010 and the interviews from the field study, such as one-child policy and the unbalanced sex ratio with the familiar context parents used different strategies in raising their sons and daughters so as to best hold their own interests, causing inequality between females and males. Then this was broken by the independence of rural women and the phenomenon of cross-regional marriage after the free mobility of labor resource between rural areas and urban areas which gives women equal rights to choose their spouses together with some publicly policies that accelerate the decline of patriarchy. In the end, the author spells out a framework of migration influence on rural marriage for some theoretical and policy implications of the findings.

Keywords: marriage, rural China, rural-urban migration, gender stratification, bride price

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1 Social Inclusion of Rural Elderly Left Behind by Internal Labor Migration: A Case Study in a Chinese Rural Village in Anhui Province

Authors: Lei Liu

Abstract:

Since the famous opening up and reform strategy of China, lots of migrants have flowed from rural areas to urban areas. In this paper, the author investigates the rural elderly left behind, which are defined aged people left alone at home while their adult children have to migrant outside. This phenomenon is a quite general and serious social problem that cannot be ignored, accompanied by the process of urbanization and regional transferring of rural labor. The Chinese internal migration not only exerts great influence to China’s economy and urbanization but also obviously reduces the labor and care to rural aged people. Contrary to assumptions in some migration and aging studies, which show the inevitable negative effects of migration upon the old age care, the author highlights unique features in their daily strategies of house holding to integrate into society with the analysis of the conception of social inclusion. Through life history interviews with elderly left behind in one rural village, this article sheds light on three different factors of social inclusion, namely, economic inclusion, social identity and political inclusion and shows its necessaries to fully understand the status of the social wellbeing of rural elderly left behind.

Keywords: Social Inclusion, labor migration, elderly left behind, rural China

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