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Chinese Physics B 2011年第4期20卷 16-26页

作者： s.Lakshmanan P.Balasubramaniam Department of Mathematics Gandhigram Rural University

This paper studies the problem of linear matrix inequality （LMI） approach to robust stability analysis for stochastic neural networks with a time-varying delay. By developing a delay decomposition approach, the information of the delayed plant states can be taken into full consideration. Based on the new Lyapunov-Krasovskii functional, some inequality techniques and stochastic stability theory, new delay-dependent stability criteria are obtained in terms of LMIs. The proposed results prove the less conservatism, which are realized by choosing new Lyapunov matrices in the decomposed integral intervals. Finally, numerical examples are provided to demonstrate the less conservatism and effectiveness of the proposed LMI method.

关键词： delay-dependent stability linear matrix inequality Lyapunov-Krasovskii functional stochastic neural networks

Nonlinear integral resonant controller for vibration reduction in nonlinear systems

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Acta Mechanica sinica 2016年第5期32卷 925-934页

作者： Ehsan Omidi s.Nima Mahmoodi Nonlinear Intelligent structures Laboratory Department of Mechanical Engineering The University of Alabama

A new nonlinear integral resonant controller（NIrC） is introduced in this paper to suppress vibration in nonlinear oscillatory smart structures. The NIrC consists of a first-order resonant integrator that provides additional damping in a closed-loop system response to reduce highamplitude nonlinear vibration around the fundamental resonance frequency. The method of multiple scales is used to obtain an approximate solution for the closed-loop *** closed-loop system stability is investigated using the resulting modulation equation. Finally, the effects of different control system parameters are illustrated and an approximate solution response is verified via numerical simulation *** advantages and disadvantages of the proposed controller are presented and extensively discussed in the results. The controlled system via the NIrC shows no high-amplitude peaks in the neighboring frequencies of the resonant mode,unlike conventional second-order compensation *** makes the NIrC controlled system robust to excitation frequency variations.

关键词： Active vibration control Cantilever Highamplitude oscillation Method of multiple scales Nonlinear vibration Piezoelectric actuator smart structure

study of Pulsed Plasma in a Crossed Flow Dielectric Barrier Discharge reactor for Improvement of NO_x removal in raw Diesel Engine Exhaust

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Plasma science and Technology 2011年第1期13卷 82-87页

作者： sankarsan MOHAPATrO B.s.rAJANIKANTH High Voltage Lab Indian Institute of Science

Improved performance of plasma in raw engine exhaust treatment is reported. A new type of reactor referred to as of cross-flow dielectric barrier discharge （DBD） was used, in which the gas flow is perpendicular to the corona electrode. In raw exhaust environment, the cross-flow （radial-flow） reactor exhibits a superior performance with regard to NOx removal when compared to that with axial flow of gas. Experiments were conducted at different flow rates ranging from 2 L/min to 25 L/min. The plasma assisted barrier discharge reactor has shown encouraging results in NOx removal at high flow rates.

关键词： electric discharges NOx removal, non-thermal plasma, raw diesel engine exhaust

Preparation of fly ash and rice husk ash geopolymer

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International Journal of Minerals,Metallurgy and Materials 2009年第6期16卷 720-726页

作者： s. Detphan P. Chindaprasirt Department of Civil Engineering Khon Kaen University

The geopolymer of fly ash （FA） and rice husk ash （rHA） was prepared. The burning temperature of rice husk, the rHA fineness and the ratio of FA to rHA were studied. The density and strength of the geopolymer mortars with rHA/FA mass ratios of 0/100, 20/80, 40/60, and 60/40 were tested. The geopolymers were activated with sodium hydroxide （NaOH）, sodium silicate, and heat. It is revealed that the optimum burning temperature of rHA for making FA-rHA geopolymer is 690oC. The as-received FA and the ground rHA with 1%-5% retained on No.325 sieve are suitable source materials for making geopolymer, and the obtained compressive strengths are between 12.5-56.0 MPa and are dependent on the ratio of FA/rHA, the rHA fineness, and the ratio of sodium silicate to NaOH. relatively high strength FA-rHA geopolymer mortars are obtained using a sodium silicate/NaOH mass ratio of 4.0, delay time before subjecting the samples to heat for 1 h, and heat curing at 60oC for 48 h.

关键词： geopolymer fly ash rice husk ash sodium hydroxide sodium silicate

Output only modal identification and structural damage detection using time frequency & wavelet techniques

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Earthquake Engineering and Engineering Vibration 2009年第4期8卷 583-605页

作者： s.Nagarajaiah B.Basu Dept.of Civil & Environmental Eng.and Dept.of Mechanical Eng.& Material sc. Rice University Dept.of Civil Structural& Environmental Eng.Trinity College Dublin

The primary objective of this paper is to develop output only modal identification and structural damage detection. Identification of multi-degree of freedom （MDOF） linear time invariant （LTI） and linear time variant （LTV--due to damage） systems based on Time-frequency （TF） techniques--such as short-time Fourier transform （sTFT）, empirical mode decomposition （EMD）, and wavelets--is proposed. sTFT, EMD, and wavelet methods developed to date are reviewed in detail. In addition a Hilbert transform （HT） approach to determine frequency and damping is also presented. In this paper, sTFT, EMD, HT and wavelet techniques are developed for decomposition of free vibration response of MDOF systems into their modal components. Once the modal components are obtained, each one is processed using Hilbert transform to obtain the modal frequency and damping ratios. In addition, the ratio of modal components at different degrees of freedom facilitate determination of mode shape. In cases with output only modal identification using ambient/random response, the random decrement technique is used to obtain free vibration response. The advantage of TF techniques is that they arc signal based; hence, can be used for output only modal identification. A three degree of freedom 1：10 scale model test structure is used to validate the proposed output only modal identification techniques based on sTFT, EMD, HT, wavelets. Both measured free vibration and forced vibration （white noise） response are considered. The secondary objective of this paper is to show the relative ease with which the TF techniques can be used for modal identification and their potential for real world applications where output only identification is essential. recorded ambient vibration data processed using techniques such as the random decrement technique can be used to obtain the free vibration response, so that further processing using TF based modal identification can be performed.

关键词： Time-frequency methods short time Fourier transform Hilbert transform wavelets modal identification:output only structural health monitoring damage detection

Effects of γ-irradiation and Deformation Temperature on Tensile Properties of Pb-2 mass% sb Alloy

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Journal of Iron and steel research International 2016年第7期23卷 733-738页

作者： Gh MOHAMMED s.EI-GAMAL Physics Department Faculty of ScienceNorthern Borders University Physics Department Faculty of EducationAin Shams University

Effects ofγ-irradiation and deformation temperature（T）on the tensile properties of Pb-2mass% sb alloys were *** samples were annealed at 458 Kfor 2hin air,then water quenched after they wereγ-irradiated（the different doses were 0.5,1.0,1.5,and 2.0 MGy）.The tensile properties were performed using stress-strain measurements at a constant strain rate（1.2×10^（-3） s^（-1））and at different T（303-393K）.It was found that at constant dose,the fracture stress（σF）decreases while the fracture strain（εF）increases as *** particular T,σFincreases whileεFdecreases with increasing *** strain-hardening exponent（n）,which is the slope of the relation between ln（σ）and ln（ε）of the parabolic part of the stress-strain curve,was determined and its values increase as Tincreases and decrease as the dose *** value of the activation energy increases as the dose increases from 0.07 eV for un-irradiated sample to 0.1eV for the 2 MGy-irradiated *** values are in accordance with that needed for dislocation movement and ordering *** interpretation of the results was given,based on the creation of point and line defects due toγ-irradiation,and that results in a distribution of beta phase（sb-phase）,leading to a difficulty in the movement of dislocations,so there is an increase in alloy hardness.

关键词： γ-irradiation deformation temperature tensile property Pb-2 mass% sb alloy

repetitive Thermomechanical Processing towards Ultra Fine Grain structure in 301,304 and 304L stainless steels

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Journal of Materials science & Technology 2011年第4期27卷 338-343页

作者： A.Momeni s.M.Abbasi Department of Mining and Metallurgical Engineering Amirkabir University of Technology KNT University of Technology

Thermomechanical processing as a combination of cold rolling and annealing was performed on austenitic stainless steels 301,304 and 304L. Two cold rolling steps each one up to a reduction of 75% were combined with an intermediate annealing at 800℃ for 20 min. The final annealing was performed *** same temperature and time. Cold rolling contributed to martensite formation at the expense of metastable austenite in the studied materials. Austenite in 301 was found to be less stable than that in 304 and 304L. Hence, higher strength characteristics in the as-quenched 301 stainless steels were attributed to the higher volume fraction of martensite. Both α′-martensite and ε-martensite were found to form as induced by deformation. However, the intensity of ε-martensite increased as the stability of austenite decreased. Annealing after cold rolling led to the reversion of austenite with an ultra fine grained structure in the order of 0.5-1 μm from the strain induced martensite. The final grain size was found to be an inverse function of the amount of strain induced martensite. The thermomechanical processing considerably improved the strength characteristics while the simultaneous decrease of elongation was rather low.

关键词： Austenitic stainless steel Cold rolling Ultra fine grain Deformation induced martensite

Host-parasite interactions under extreme climatic conditions

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Current Zoology 2011年第3期57卷 390-405页

作者： J. MArTINEZ s. MErINO Departamento de Microbiologfa y Parasitologfa Facultad de Farmacia Universidad de Alcala Alcala de Henares Madrid Spain Departamento de Ecologfa Evolutiva Museo Nacional de Ciencias Naturales Consejo Superior de Investigaciones Cientfficas Madrid Spain

The effect that climatic changes can exert on parasitic interactions represents a multifactor problem whose results are difficult to predict. The actual impact of changes will depend on their magnitude and the physiological tolerance of affected organisms. When the change is considered extreme （i.e. unusual weather events that are at the extremes of the historical distribution for a given area）, the probability of an alteration in an organisms＇ homeostasis increases dramatically. However, factors determining the altered dynamics of host-parasite interactions due to an extreme change are the same as those acting in response to changes of lower magnitude. Only a deep knowledge of these factors will help to produce more accurate predictive models for the effects of extreme changes on parasitic interactions. Extreme environmental conditions may affect pathogens directly when they include free-living stages in their life-cycles and indirectly through reduced resource availability for hosts and thus reduced ability to produce efficient anti-parasite defenses, or by effects on host density affecting transmission dynamics of diseases or the frequency of intraspecific contact. What are the consequences for host-parasite interactions？ Here we summarize the present knowledge on three principal factors in determining host-parasite associations; biodiversity, population density and immunocompetence In addition, we analyzed examples of the effects of environmental alteration of anthropogenic origin on parasitic systems because the effects are analogous to that exerted by an extreme climatic change [Current Zoology 57 （3）： 390405, 2011].

关键词： Biodiversity Climate change Immunocompetence Parasite-host interactions Pollution Population density

G-type dispersion equation under suppressed rigid boundary:analytic approach

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Applied Mathematics and Mechanics(English Edition) 2016年第4期37卷 501-512页

作者： s.K.VIsHWAKArMA runzhang XU College of Automation Harbin Engineering University Department of Mathematics Birla Institute of Technology and Science (BITS)Pilani Hyderabad Campus College of science Harbin Engineering University

This paper studies dispersion of a G-type earthquake wave under the influence of a suppressed rigid boundary. Inside the Earth, the density and rigidity of the crustal layer and the mantle of the Earth vary exponentially and periodically along the depth. The displacements of the wave are found in the individual medium followed by a dispersion equation using a suitable analytic approach and a boundary condition. The prominent effect of inhomogeneity contained in the media, the rigid boundary plane, and the initial stress on the phase and group velocities is shown graphically.

关键词： G-type wave analytic approach dispersion equation group velocity rigid boundary

BEsT WEIGHT PATTErN EVALUATION BAsED sECUrITY CONsTrAINED POWEr DIsPATCH ALGOrITHM

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Journal of systems science and systems Engineering 2007年第3期16卷 287-307页

作者： Lakhwinder sINGH J.s. DHILLON Baba Banda singh Bahadur Engineering College Fatehgarh Sahib- 140407 Punjab India sant Longowal Institute of Engineering & Technology Longowa1-148 106 Punjab India

This paper presents a methodology which determines the allocation of power demand among the committed generating units while minimizes number of objectives as well as meets physical and technological system constraints. The procedure considers two decoupled problems based upon the dependency of their goals on either active power or reactive power generation. Both the problems have been solved sequentially to achieve optimal allocation of active and reactive power generation while minimizes operating cost, gaseous pollutants emission objectives and active power transmission loss with consideration of system operating constraints along with generators prohibited operating zones and transmission line flow limits. The active and reactive power line flows are obtained with the help of generalized generation shift distribution factors （GGDF） and generalized Z-bus distribution factors （GZBDF）, respectively. First problem is solved in multi-objective framework in which the best weights assigned to objectives are determined while employing weighting method and in second problem, active power loss of the system is minimized subject to system constraints. The validity of the proposed method is demonstrated on 30-bus IEEE power system.

关键词： Multi-objective optimization best weight pattern evaluation fuzzy decision making membership function generalized generation shift distribution factors generalised Z-bus distribution factors