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Search Results: 1 - 10 of 90955 matches for " LIU Hao "
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H Finite-Time Control for Switched Linear Systems with Time-Varying Delay  [PDF]
Hao Liu, Yi Shen
Intelligent Control and Automation (ICA) , 2011, DOI: 10.4236/ica.2011.23025
Abstract: Finite-time boundedness and H finite-time boundedness of switched linear systems with time-varying delay and exogenous disturbances are addressed. Based on average dwell time (ADT) and free-weight matrix technologies, sufficient conditions which can ensure finite-time boundedness and H finite-time boundedness are given. And then in virtue of the results on finite-time boundedness, the state memory feedback controller is designed to H finite-time stabilize a time-delay switched system. These conditions are given in terms of LMIs and are delay-dependent. An example is given to illustrate the efficiency of the proposed method.
Regional Differences and Convergence Analysis of Green Energy Efficiency in China  [PDF]
Xiaoyu Liu, Hao Li
Journal of Power and Energy Engineering (JPEE) , 2018, DOI: 10.4236/jpee.2018.66004
Abstract: As an important aspect for the survival and development of human society, energy is an important factor that restricts the economic and social development of a country. This paper measured the green energy efficiency of thirty provinces of China from 2000 to 2016 by using the Super-SBM, introducing it to the spatial economic model to study the convergence of green energy efficiency. The results show that: the overall green energy efficiency of China shows a downward trend with time, and it gradually decreases from east to west. The three regions have significant differences. Among them, there is no β absolute convergence trend for the eastern, central, western regions and the country as a whole, but there is β relative convergence. The level of economic development, R & D investment, the level of technology improvement, and foreign direct investment have positive effects on the development of green energy efficiency. The industrial structure has a positive effect in the eastern but a negative effect in the western.
A Quick Classification Method of the Power Quality Disturbances  [PDF]
Yi Yi Tang, Hao Liu
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.67040
Abstract:

This paper introduces a quick classification method of the power quality disturbances. Based on analyzing the characteristics of different electrical disturbance signals in time domain, four distinctive features are extracted from electrical signals for classifying different power quality disturbances and then an automatic classifier is proposed. Using the proposed classification method,a PQ monitor of the classifying power quality disturbances is developed based on the TMS320F2812DSP micro-processor. Semi-physical simulation, lab experiment and field measurement results have verified that this proposed method can classify single or complex disturbance signals effectively.

The Robust Pole Assignment Problem for Second-Order Systems
Hao Liu
Mathematical Problems in Engineering , 2010, DOI: 10.1155/2010/796143
Abstract: Pole assignment problems are special algebraic inverse eigenvalue problems. In this paper, we research numerical methods of the robust pole assignment problem for second-order systems. The problem is formulated as an optimization problem. Depending upon whether the prescribed eigenvalues are real or complex, we separate the discussion into two cases and propose two algorithms for solving this problem. Numerical examples show that the problem of the robust eigenvalue assignment for the quadratic pencil can be solved effectively. 1. Introduction Pole assignment problems are special algebraic inverse eigenvalue problems [1, 2]. The nature model for the vibrating systems, arising in a wide range of applications, especially in the design and analysis of vibration structures, such as bridges, buildings, and airplanes, can be described by the second-order differential equation. The properties of systems of second-order differential equation are governed by its associated quadratic eigenvalue problem (QEP). To avoid unwanted oscillations of the vibratory system, pole assignment can change the poles of the system by choosing a control force and improve its stability. Consider the following second-order matrix differential equation: where the dots denote differentiation with respect to time, and and are real symmetric matrices; is positive definite (denoted by ). Separation of variables where , is a constant vector, in (1.1), leads to the following quadratic eigenvalue problem: where is quadratic pencil. In general, the eigenvalues of are named poles of system (1.1). In engineering, the dynamics of equation (1.1) can be modified by applying a control force , where . The relation (1.1) now becomes The special choice where and are real matrices, is called state feedback control, and (1.1) becomes The associated quadratic eigenvalue problem becomes where is a closed-loop pencil. The quadratic eigenvalue assignment problem is stated explicitly as follows. Problem QEA Given real matrices and , and a set of complex numbers , closed under complex conjugation, find real matrices such that the eigenvalues of are equal to . Conditions for the existence of solutions to problem QEA are known as in the following theorem. Theorem 1.1 (see [3]). Solutions to problem QEA exist for every set of self-conjugate complex numbers if and only if the system (1.1) is completely controllable, that is In a realistic situation, it is desirable to choose the feedback to ensure that the eigenstructure of closed-loop system is as robust, or insensitive to perturbation in the system matrices
Effects of Tongbi Mixture 2 on expressions of CD28 and CD152 and content of tumor necrosis factor-alpha in peripheral blood in rats with collagen-induced arthritis
Hao LIU
Zhong Xi Yi Jie He Xue Bao , 2008,
Abstract: Objective: To study the effects of Tongbi Mixture 2, a compound traditional Chinese herbal medicine for treating rheumatoid arthritis (RA), on immunoregulation of T lymphocytes in rats with collagen-induced arthritis (CIA).Methods: Forty Wistar rats were randomly divided into normal control group, untreated group, Tongbi Mixture 2-treated group, methotrexate (MTX)-treated group and Tripterygium wilfordii polyglycoside (TWP)-treated group. Except for the rats of the normal control group (injection with normal saline), rats of the other four groups were subcutaneouly multipoint-injected with collagen protein Ⅱ to induce CIA. The rats were treated with normal saline, Tongbi Mixture 2, MTX tablets and TWP tablets respectively for 36 days. The expressions of CD28 and CD152 were detected by flow cytometry, while the content of tumor necrosis factor-alpha (TNF-α) was analyzed by enzyme-linked immunosorbent assay.Results: The expression of CD28 among the three drug treated groups had no statistical difference (P>0.05), while significantly higher than that of the normal control group (P<0.01) and lower than that of the untreated group (P<0.01). The expression of CD152 in the Tongbi Mixture 2 treated-group was lower than those of the MTX- and TWP-treated groups (P<0.05, P<0.01), but had no statistical difference as compared with the normal control group (P>0.05). There were no statistical differences in content of TNF-α between the drug treated groups and the normal control group (P>0.05), but the content of TNF-α of the drug treated groups was lower than that of the untreated group (P<0.05 or P<0.01).Conclusion: Tongbi Mixture 2 can inhibit T lymphocytes through down-regulating the expressions of CD28 and CD152 and the content of TNF-α, which may be the major mechanisms in treating RA
Evidence of s-channel Single Top Quark Production in Events with one Charged Lepton and Bottom Quark Jets at CDF
Hao Liu
Physics , 2013,
Abstract: We report an evidence of \textit{s}-channel single top quark production in $p\bar{p}$ collision at $\sqrt{s}= 1.96 \mathrm{TeV}$ using data with integrated luminosity of $9.4 \mathrm{fb}^{-1}$ collected by the Collider Detector at Fermilab (CDF). We select events with one charged lepton, large missing transverse energy and two bottom quark jets. The observed significance of the result is 3.8 standard deviation from background only prediction. We measure the inclusive cross section to be $1.41^{+0.44}_{-0.42}\mathrm{(stat+syst)} \mathrm{pb}$ assuming $m_t = 172.5 \mathrm{GeV}/c^2$.
A Velocity-Adaptive Handover Scheme for Mobile WiMAX  [PDF]
Caiyong HAO, Hongli LIU, Jie ZHAN
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.29101
Abstract: Mobile WiMAX is a wireless networking system based on the IEEE 802.16e standard. In order to support mobile, some kinds of handover schemes must be adopted, and the hard handover is defined as mandatory. Since the data transmission should be paused during the hard handover process, it causes handover delay in mobile communication. The handover delay makes severe degradation in system performance when implemented in real-time applications such as IPTV and VoIP. The existing draft standard considers only the received signal strength when deciding handover initiation. However, the velocity factor also has an important influence on handover initiation and can not be neglected. To deal with these problems, this article proposes a velocity-adaptive handover scheme. This scheme adopts dynamic handover threshold according to different velocity to skip some unnecessary handover stages, reduces handover delay and enhances the network resource utilization. The simulation result and performance analysis validate the efficiency of the proposed scheme.
A Wideband Circularly Polarized Patch Antenna for 60 GHz Wireless Communications  [PDF]
Rongguo Zhou, Duixian Liu, Hao Xin
Wireless Engineering and Technology (WET) , 2012, DOI: 10.4236/wet.2012.33016
Abstract: This paper presents the design of a fully packaged 60 GHz wideband patch antenna incorporating an air cavity and a fused silica superstrate. Circular polarization (CP) is realized by introducing a diagonal slot at the center of the square patch. By optimizing the patch and the slot dimensions, a high efficiency (>90%) microstrip fed CP antenna with an impedance bandwidth of 24% and a 6 dB axial ratio bandwidth of 21.5% is designed. A coplanar waveguide (CPW) to microstrip transition with λ/4-open-ended stubs are then designed to match the antenna to the CPW packaging interface. The experimental results of the final packaged antenna agree reasonably with the simulation results, demonstrating an impedance bandwidth of more than 26% and a 6 dB axial ratio bandwidth of 22.7%.
Primary and secondary school mental health teachers in professional identity of intervention programs  [PDF]
Hao Lei, Cheng Guo, Yanling Liu
Health (Health) , 2012, DOI: 10.4236/health.2012.412191
Abstract: To explore the impact of teacher training on the professional identity of primary and secondary school mental health teachers, this study conducted a half-month professional development training program to 54 primary and secondary school mental health teachers, and performed measurement on the professional identity of the teachers in the experimental group and the control group with “Teachers’ Professional Identity Questionnaire”. The result shows that after the training there is a significant improvement in the professional identity of the teachers in the experimental group, and the teachers’ scores on the four dimensions of profession identity: the sense of role, the professional behavioral tendency, the occupational values, and the sense of belonging, all increased significantly. This indicates that the curriculum intervention for the primary and secondary school mental health teachers could effectively improve the teachers’ professional identity.
Research for Merger and Acquisition of Petrochemical Industries Based on Value Chain  [PDF]
Qing Li, Hao Cheng, Yanjun Liu
Open Journal of Applied Sciences (OJAppS) , 2013, DOI: 10.4236/ojapps.2013.31011
Abstract:

Based on the analysis of the theories of value chain and multinational merger and acquisition, we research the merger and acquisition of petrochemical industries based on value chain, according to the trait of the value chain of the petrochemical industries. And we propose the implementation process and the integration method for the merger and acquisition of petrochemical industries based on value chain.

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