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Browsing Research Articles (University of Pretoria) by UP Author "Zhang, Jiangfeng"
Now showing items 1-20 of 22
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Liang, Xiyin; Zhang, Jiangfeng; Xia, Xiaohua (Institute of Electrical and Electronics Engineers, 2008-08)In literature it is conjectured that the states of the generalized Lorenz system with an unknown parameter can not be estimated by adaptive observers. In this paper we show that this unknown parameter and the states can ...
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Xia, Xiaohua; Zhang, Jiangfeng; Elaiw, A.M. (Elsevier, 2011-06)Two formulations exist for the problem of the optimal power dispatch of generators with ramp rate constraints: the optimal control dynamic dispatch (OCDD) formulation based on control system models, and the dynamic economic ...
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Ye, Yuxiang; Koch, Steven F.; Zhang, Jiangfeng (Elsevier, 2018-09)Little is known about residential electricity demand in developing countries. In order to shed some light on this topic, this study combines data from South Africa's recent Income and Expenditure Survey with data from the ...
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Qu, Shaocheng; Xia, Xiaohua; Zhang, Jiangfeng (Institute of Electrical and Electronics Engineers, 2014-09)The dynamical behaviors of an Euler discretized slidingmode control (SMC) systems based on equivalent control strategy are studied. A periodic-2 orbit in steady state is found for the switching function of the Euler ...
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Qu, Shaocheng; Xia, Xiaohua; Zhang, Jiangfeng (Institute of Electrical and Electronics Engineers, 2014-07)In this paper, dynamical behaviors of the discretetime sliding-mode-control (DSMC) uncertain systems are studied. First, a discrete reaching law with a disturbance compensator is presented, and a sliding-mode controller ...
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Ye, Xianming; Xia, Xiaohua; Zhang, Jiangfeng; Chen, Yangquan (Institution of Engineering and Technology, 2013)Long-range dependence (LRD) is discovered in time series arising from different fields, especially in network traffic and econometrics. Detecting the presence and the intensity of LRD plays a crucial role in time-series ...
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Xia, Xiaohua; Zhang, Jiangfeng; Cass, William (Energy Research Insitute, University of Cape Town, 2012-02)This paper aims at analyzing the energy management activities for commercial buildings of a financial service company in South Africa by energy efficiency in terms of performance, operation, equipment and technology ...
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Xia, Xiaohua; Zhang, Jiangfeng (Institute of Electrical and Electronics Engineers, 2010-06)The analytic concept of steady states for nonlinear systems was introduced by Isidori and Byrnes, and its geometric properties were also given implicitly mixed with the solvability of the output regulation problem for ...
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Ekpenyong, Uduakobong Edet; Zhang, Jiangfeng; Xia, Xiaohua (Elsevier, 2015-12)The expected savings from energy efficiency projects are divided into two, direct savings and indirect savings. Direct savings refer to savings obtained through the personal effort of an individual implemen-ting some ...
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Improving energy efficiency of cyclone circuits in coal beneficiation plants by pump-storage systems Zhang, Lijun; Xia, Xiaohua; Zhang, Jiangfeng (Elsevier, 2014-04)A pump storage system (PSS) is introduced to the coal preparation dense medium cyclone (DMC) plants to improve their energy efficiency while maintaining the required medium supply. The DMC processes are very energy ...
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Liang, Xiyin; Zhang, Jiangfeng; Xia, Xiaohua (IEEE, 2008-07)A secure chaos-based communication with a ∆-modulated chaotic cryptographic technique is developed in this paper. We prove that a ∆-modulated feedback control of a 1-D discrete-time control system gives rise to a chaotic ...
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Ekpenyong, Uduakobong Edet; Zhang, Jiangfeng; Xia, Xiaohua (Elsevier, 2014-12)In this paper, a mathematical model is formulated to quantify the social im- pact an individual has on his/her community when he/she performs any energy e ciency project and transmits that information to his/her neighbours. ...
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Zhang, Lijun; Xia, Xiaohua; Zhang, Jiangfeng (Institute of Electrical and Electronics Engineers, 2015-05)The dense medium cyclone (DMC) process used in coal beneficiation plants is studied from a control system perspective. Employing the dynamic model of the DMC process derived from mass flow balance, a model based control ...
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Tazvinga, Henerica; Xia, Xiaohua; Zhang, Jiangfeng (Elsevier, 2013)Hybrid systems present a new dimension to the time correlation of intermittent renewable energy sources. The paper considers the daily energy consumption variations for winter and summer weekdays and weekends in order to ...
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Zhang, Jiangfeng; Xia, Xiaohua (Elsevier, 2011-02)This paper proposes a model predictive control (MPC) approach to the periodic implementation of the optimal solutions of a class of resource allocation problems in which the allocation requirements and conditions repeat ...
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Xia, Xiaohua; Zhang, Jiangfeng (Institute of Electrical and Electronics Engineers, 2011-08)No abstract available.
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Wang, Bo; Xia, Xiaohua; Zhang, Jiangfeng (Elsevier, 2014-07)The building sector contributes a large proportion of the world’s total final energy consumption. As aresult, considerable attention has been paid to energy efficiency in the building sector. At the current stage,building ...
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Malatji, Esrom Mahlatsi; Zhang, Jiangfeng; Xia, Xiaohua (Elsevier, 2013-06)A multiple objective optimisation model is formulated to help decision makers to make an optimal decision when investing in energy-efficient building retrofitting. The objectives are to maximise the energy savings and ...
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Badenhorst, Werner; Zhang, Jiangfeng; Xia, Xiaohua (Elsevier, 2011)This paper presents a near optimal hoist scheduling and control program for rock winders found in South African deep level mines in the context of demand side management and time-of-use (TOU) tariffs. The objective is to ...
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Ye, Xianming; Xia, Xiaohua; Zhang, Jiangfeng (Elsevier, 2013)Clean development mechanism (CDM) project developers are always interested in achieving required measurement accuracies with the least metering cost. In this paper, a metering cost minimisation model is proposed for the ...
Now showing items 1-20 of 22