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Frequency-domain generelaized singular peruturbation method for relative error model order reduction

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控制理论与应用（英文版） 2009年第1期7卷 57-62页

作者： hamid Reza SHAKER Section for Automation and Control Institute for Electronic SystemsAalborg University

A new mixed method for relative error model order reduction is proposed. In the proposed method the frequency domain balanced stochastic truncation method is improved by applying the generalized singular perturbation method to the frequency domain balanced system in the reduction procedure. The frequency domain balanced stochastic truncation method, which was proposed in [15] and [17] by the author, is based on two recently developed methods, namely frequency domain balanced truncation within a desired frequency bound and inner-outer factorization techniques. The proposed method in ttiis paper is a carry over of the frequency-domain balanced stochastic truncation and is of interest for practical model order reduction because in this context it shows to keep the accuracy of the approximation as high as possible without sacrificing the computational efficiency and important system properties. It is shown that some important properties of the frequency domain stochastic balanced reduction technique are extended to the proposed reduction method by using the concept and properties of the reciprocal systems. Numerical results show the accuracy, simplicity and flexibility enhancement of the method.

关键词： Large-scale systems Model reduction Balanced realization Frequency-domain Grammian

Modeling the oxidative coupling of methane: Heterogeneous chemistry coupled with 3D flow field simulation

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Journal of Natural Gas Chemistry 2009年第1期18卷 39-44页

作者： Yaghobi Nakisa Ghoreishy Mir hamid Reza Iran Polymer and Petrochemical Institute P. O. Box 14965/115 Tehran Iran

The oxidative coupling of methane （OCM） over titanate perovskite catalyst has been developed by three-dimensional numerical simulations of flow field coupled with heat transfer as well as heterogeneous kinetic model. The reaction was assumed to take place both in the gas phase and on the catalytic surface. Kinetic rate constants were experimentally obtained using a ten step kinetic model. The simulation results agree quite well with the data of OCM experiments, which were used to investigate the effect of temperature on the selectivity and conversion obtained in the methane oxidative coupling process. The conversion of methane linearly increased with temperature and the selectivity of C2 was practically constant in the temperature range of 973-1073 K. The study shows that CFD tools make it possible to implement the heterogeneous kinetic model even for high exothermic reaction such as OCM.

关键词： OCM simulation kinetics fixed bed catalytic reactor ethylene

Effect of Silica Fume on Compressive Strength of Oil-Polluted Concrete in Different Marine Environments

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China Ocean Engineering 2017年第6期31卷 716-723页

作者： hamid SHAHRABADI Sina SAYAREH Hamed SARKARDEH Department of Civil Engineering Chabahar Maritime UniversityChabaharIran Department of Civil Engineering University of Sistan&BaluchestanZahedanIran Department of Civil Engineering Faculty of EngineeringHakim Sabzevari UniversitySabzevarIran

In the present research, effect of silica fume as an additive and oil polluted sands as aggregates on compressive strength of concrete were investigated experimentally. The amount ofoil in the designed mixtures was assumed to be constant and equal to 2% of the sand weight. Silica fume accounting for 10%, 15% and 20% of the weight is added to the designed mixture. After preparation and curing, concrete specimens were placed into the three different conditions： fresh, brackish and saltwater environments （submerged in fresh water, alternation of exposed in air ＆ submerged in sea water and submerged in sea water）. The result of compressive strength tests shows that the compressive strength of the specimens consisting of silica fume increases significantly in comparison with the control specimens in all three environments. The compressive strength of the concrete with 15% silica fume content was about 30% to 50% higher than that of control specimens in all tested environments under the condition of using polluted aggregates in the designed mixture.

关键词： compressive strength water environments oil polluted sands silica fume marine concrete structures

Stabilization of switched systems with all unstable modes:application to the aircraft team problem

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Journal of Systems Engineering and Electronics 2019年第4期30卷 792-798页

作者： TAVAKOLIFAR Dariush KHALOOzadEH hamid AMJADIFARD Roya Department of Electrical Engineering Science and Research BranchIslamic Azad UniversityTehran ***Iran Department of Systems and Control K.N.Toosi University of TechnologyTehran ***Iran Department of Electrical&Computer Engineering Kharazmi UniversityTehran ***Iran

The method of stabilizing switched systems based on the optimal control is applied,with all modes unstable,for a typical example of the multi-agent ***,the optimal control method for stabilizing switched systems is *** this purpose,a switching table rule procedure is *** procedure is inspired by the optimal control that identifies the optimal trajectory for the switched *** the next step,the stability of a multi-agent system is studied,considering different unstable connection ***,the optimal control method is successfully applied to an aircraft team,as an example of the multi-agent *** results evaluate and confirm the successful application of this method in the aircraft team example.

关键词： switched system multi-agent system stabilization optimal control unstable modes aircraft team

Effects of cathodic component of current on porosity and hardness characteristics of micro plasma oxidation(MPO) coatings on aluminum alloy

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中国有色金属学会会刊：英文版 2005年第1期15卷 113-118页

作者： Samir hamid Awad 钱翰城 School of Mechanical Engineering Chongqing University Chongqing 400044 China

Micro plasma oxidation(MPO) has recently been investigated as a novel, rapid and effective means to provide modified surfaces with improved properties of load bearing and wear resistance on light alloys particularly aluminum alloys. MPO is a multifactor-controlled process, these factors must be controlled to produce high quality coatings. The main research emphasis in MPO coating development over the past years seems to be the attainment of higher hardness levels and thick coatings. The porosity of MPO coating is the most complex phenomenon affecting the distribution, levels and the measurements of the hardness; and it is controlled by suitable selection of important parameters such as the electrical conditions. Ceramics coatings were synthesized on Al substrate by MPO to examine the effects of adding a cathodic phase alternated with anodic-cathodic current on the porosity and hardness characteristics of coatings by X-ray diffraction(XRD), scanning electron microscopy(SEM), and microhardness tester. The coatings produced by the combined mode are more dense and less porous than that by the anodic-cathodic mode. (Microhardness) test shows that the coatings produced by the combined mode exhibit both the highest hardness, and less reduction percentage in hardness with increasing the coatings thickness. These improvements become more significant for the polished and thicker coatings.

关键词：微观等离子体氧化铝合金硬度多孔材料

INFORMATION SHARING AND STRATEGIC SIGNALING IN SUPPLY CHAINS

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Journal of Systems Science and Systems Engineering 2009年第2期18卷 129-158页

作者： Robert J.KAUFFMAN hamid MOHTADI W.P.Carey School of Business and School of Computing and InformaticsArizona State University TempeAZ85287 USA Department of Economics University of WisconsinMilwaukeeWI53201 and Credit Risk AssessmentUSBankMinneapolisMN55402USA

Information sharing in procurement occurs in rich and varied industry contexts in which managerial decisions are made and organizational strategy is formulated. We explore how information sharing ought to work in procurement contexts that involve investments in inter-organizational information systems （IOS） and collaborative planning, forecasting and replenishment （CPFR） practices. How and under what circumstances does a firm that plays the role of a supply chain buyer decide to share information on key variables, such as point-of-sale consumer demand data with its supplier, up the supply chain？ This is a key issue that crosses the boundary between supply chain management and information systems （IS） management. The answers that we provide are based on our use of a game-theoretic signaling model of buyer and supplier strategy in the presence of uncertainties about final consumer demand. We also explore the connection between operational costs that are associated with the firm＇s information sharing and information withholding strategies. Our results provide normative guidance to supply chain buyers about how to interpret different demand uncertainty scenarios to improve their decisions and generate high value. From the IS management perspective, we show the impacts on the firm of different information sharing approaches that are made possible by present day technologies.

关键词： Anticipated over-supply collaborative planning forecasting and replenishment (CPFR) demand forecasting economic analysis information sharing information systems (IS) signaling supply chain management

Adaptive H_∞ Synchronization of Master-slave Systems with Mixed Time-varying Delays and Nonlinear Perturbations: An LMI Approach

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International Journal of Automation and computing 2011年第4期8卷 381-390页

作者： hamid Reza Karimi Department of Engineering Faculty of Engineering and Science University of Agder N-4898 Grimstad Norway

This paper proposes an adaptive synchronization problem for the master and slave structure of linear systems with nonlinear perturbations and mixed time-varying delays comprising different discrete and distributed time delays. Using an appropriate Lyapunov-Krasovskii functional, some delay-dependent sufficient conditions and an adaptation law including the master-slave parame- ters are established for designing a delayed synchronization law in terms of linear matrix inequalities（LMIs）. The time-varying controller guarantees the H ∞ synchronization of the two coupled master and slave systems regardless of their initial states. Particularly, it is shown that the synchronization speed can be controlled by adjusting the updated gain of the synchronization signal. Two numerical examples are given to demonstrate the effectiveness of the method.

关键词： Adaptive synchronization master-slave systems delay H ∞ performance nonlinear perturbations.

Influences of adsorptions of some inorganic molecules on electronic, optical, and thermodynamic properties of Mg_(12)O_(12) nanocage: A computational approach

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Chinese Physics B 2018年第8期27卷 280-289页

作者： Asghar Mohammadi Hesari hamid Reza Shamlouei Chemistry Department Lorestan UniversityI(horram AbadLorestanIraa

According to density functional theory, we investigate the effects of BF3, BF4, BCI3, A1F3, AICI3, A1Br3, 13eF3, GaF3, GaC13, GaBr3, NO3, BS2, BSO, BO2, F2, PFs, PC15, and ASF5 molecules on the geometric, electronic, linear, and nonlinear optical properties of an Mg12012 nanocage. The thermodynamic stability and feasibility of the adsorption process are investigated by analyzing the free energy. It is shown that the adsorptions of almost all molecules on the Mg12OI2 surface are exothermic. The calculations of the polarizability of these nanoclusters show that among the studied molecules, BeF3 has the largest influence on the polarizability value （a≈315 a.u., the unit a.u. is short for atomic unit）. The static first hyperpolarizability （β0） value is increased in the presence of these superhalogens. This increase is greatest for BeF3 and BF4 of which the highest value of the first hyperpolarizability （βO≈ 5775 a.u.） is related to a BeF3_c（e@Mgl2Ol2） nanocluster. The adsorption position is a key to estimating the value of increasing the first hyperpolarizability.

关键词： Mg1201 polarizability hyperpolarizability binding energy nanocage DFT calculation

Effect of CNTs and nano ZnO on physical and mechanical properties of polyaniline composites applicable in energy devices

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Progress in Natural Science:Materials International 2016年第6期26卷 517-522页

作者： Vahid Saadattalab Alireza Shakeri hamid Gholami School of Chemistry University College of Science University of Tehran

Polyaniline was synthesized chemically in an acidic medium in the presence of Ammonium Peroxydisulphate(APS) as an oxidizing agent. PANI(Polyaniline) nanocomposites were prepared in the presence of various amount of carbon nanotube and zinc oxide(from 1 to 5 wt%) by solution casting method. The free-standing film of polyaniline and its nanocomposites were obtained by vaporization of solvent content. The composition,morphology and structure of the polymer and the nanocomposites were characterized by Fourier transform infrared spectroscopy FT-IR spectra, scanning electron microscopy(SEM) image and XRD pattern. In addition,thermal stability was studied by TGA analysis, electrical conductivity was measured by four-point probe technique and mechanical properties were studied by tensile strength test. The characteristic FTIR peaks of PANI were found to shift to lower wave number in nanocomposites due to the formation of H-bonding. XRD results revealed that the crystallinity of PANI was more noticeable after addition of nano-ZnO, while the intensity of the peaks increased by the addition of ZnO nanoparticles. Furthermore, TGA results showed that the decomposition of the nanocomposite was less than that of pure polyaniline which confirms the successful fabrication of products. Young's modulus and strength at break point were increased in the case of the nanocomposite, in addition, the electrical conductivity of the PANI/ZnO nanocomposite film was found to be smaller than that of the PANI film while CNTs increase the conductivity of polyaniline.

关键词： Conductive polymer Polyaniline Nanocomposite Zinc oxide CNT