检索结果-南通市图书馆

Fault ride-through capability improvement in a DFIG-based wind turbine using modified ADRC

在线全文

学校读者我要写书评

暂无评论

Protection and Control of Modern Power Systems 2022年第1期7卷 751-787页

作者： Seyed reza Mosayyebi Seyed hamid Shahalami Hamed Mojallali Electrical Engineering Department Faculty of EngineeringUniversity of GuilanRashtIran

In this paper,an overview of several strategies for fault ride-through(FRT)capability improvement of a doubly-fed induction generator(DFIG)-based wind turbine is *** and parameter variations have adverse effects on the performance of these *** is desirable to use a control method that is robust to such *** disturbance rejection control(ADRC)is one of the most common methods for eliminating the effects of *** improve the performance of the conventional ADRC,a modified ADRC is introduced that is more robust to disturbances and offers better *** non-derivability of the fal function used in the conventional ADRC degrades its efficiency,so the modified ADRC uses alternative functions that are derivable at all points,i.e.,the odd trigonometric and hyperbolic functions(arcsinh,arctan,and tanh).To improve the effciency of the proposed ADRC,fuzzy logic and fractional-order functions are used *** fuzzy fractional-order ADRC(FFOADRC),all disturbances are evaluated using a nonlinear fractional-order extended state observer(NFESO).The performance of the suggested structure is investigated in MATLAB/*** simulation results show that during disturbances such as network voltage sag/swell,using the modified ADRCs leads to smaller fluctuations in stator flux amplitude and DC-link voltage,lower variations in DFIG velocity,and lower total harmonic distortion(THD)of the stator *** demonstrates the superiority over conventional ADRC and a proportional-integral(PI)***,by chang-ing the crowbar resistance and using the modified ADRCs,the peak values of the waveforms(torque and currents)can be controlled at the moment of fault occurrence with no significant distortion.

关键词： Doubly-fed induction generator(DFIG) Auto disturbance rejection control(ADRC) Fault ride-through(FRT) Wind turbine Nonlinear fractional-order extended state observer(NFESO)

The kinetic of mass loss of grades A and B of melted TNT by isothermal and non-isothermal gravimetric methods

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2018年第2期14卷 126-131页

作者： hamid reza Pouretedal Sajjad Damiri Parvaneh Nosrati Ehsan Forati Ghaemi Faculty of Applied Chemistry Malek-ashtar University of Technology

The kintic and activation energy of mass loss of two grades of melted TNT explosive, grade A and grade B, with freezing points of 80.57 and 78.15 ℃, respectively, were studied by isothermal and nonisothermal gravimetric methods. In isothermal method, the mass loss of samples in containers of glass and aluminum was followed in temperatures of 80, 90 and 100 ℃. The kinetic of the mass loss of the samples in the aluminum container was higher than the kinetic of it in the glass container that can be related to the effects of heat transfer and catalytic of aluminm metal. Also, the presence of impurities in grade B was due to increasing of kinetic of mass loss of it versus grade A. The non-isothermal curves were obtained in range of 30-330 ℃ at heating rates of 10,15 and 20 ℃·min^(-1).The TG/DTG data were used for determination of activation energy(E_a) of mass loss of TNT samples upon degradation by using Ozawa, Kissinger, Ozawa-Flynn-Wall(OFW) and Kissinger-Akahira-Sunose(KAS) methods as model free methods. The activation energies of grades of A and B of TNT was obtained 99-120 and 66-70 kJ mol^(-1)respectively. The lower values of activation energy of the degradation reaction of grade B confirm the effect of impurities in the kinetics of mass loss of this grade.

关键词： TNT Isothermal Non-isothermal Kinetic Mass loss

Multi-scale analysis of flow structures in fluidized beds with immersed tubes

在线全文

学校读者我要写书评

暂无评论

Particuology 2015年第4期13卷 99-106页

作者： hamid R.Norouzi Maryam Tahmasebpoor reza Zarghami Navid Mostoufi Multiphase Systems Research Lab.School of Chemical Engineering College of EngineeringUniversity of Tehran Department of Chemical and Petroleum Engineering University of Tabriz

Multi-scale analysis and non-linear analysis were combined to investigate the hydrodynamics of fluidized beds with and without horizontal tubes. Pressure fluctuations were measured and analyzed employing discrete wavelet analysis, recurrence plot analysis, and recurrence quantification analysis. A systematic procedure was followed to determine wavelet parameters. At low gas velocities, the energy of macro-structures reduces with the addition of the first tube and then increases with the addition of a second tube. However, there is no notable difference at high gas velocities. Determinism is high for the bed without tubes, which can be attributed to the periodic behavior of bubbles. Determinism decreases with the addition of tubes because the breakage of bubbles results in less periodic behavior. The three methods of analysis used in this study captured the effects of immersed tubes on the hydrodynamics of fluidized beds. Recurrence quantitative analysis was found to be a powerful and easy-to-use method that can capture the nonlinear characteristics of fluidized beds much more quickly than conventional methods of nonlinear analysis. This method can thus be effectively used for the online monitoring of hydrodynamic changes in fluidized beds.

关键词： Immersed tube Non-linear analysis Pressure fluctuations Recurrence plot Wavelet transform

Kinetics and mechanism of titanium hydride powder and aluminum melt reaction

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2012年第2期19卷 165-172页

作者： Ali Rasooli Mehdi Divandari hamid reza Shahverdi Mohammad Ali Boutorabi School of Metallurgy and Materials Engineering Member of Center of Excellence for Advanced Material and Processing (CEAMP) Iran University of Science and Technology Tehran 16844 Iran Department of Materials Faculty of Engineering Tarbiat Modaress University Tehran 14115-143 Iran

Based on the measurement of the released hydrogen gas pressure （PH2）, the reaction kinetics between TiH2 powder and pure aluminum melt was studied at various temperatures. After cooling the samples, the interface of TiH2 powder and aluminum melt was studied. The results show that the-time curves have three regions; in the first and second regions, the rate of reaction conforms zero and one order, respectively; in the third region, the hydrogen gas pressure remains constant and the rate of reaction reaches zero. The main factors that control the rate of reaction in the first and second regions are the penetration of hydrogen atoms in the titanium lattice and the chemical reaction between molten aluminum and titanium, respectively. According to the main factors that control the rate of reaction, three temperature ranges are considered for the reaction mechanism：（a） 700-750°C, （b） 750-800°C, and （c） 800-1000°C. In the first temperature range, the reaction is mostly under the control of chemical reaction; at the temperature range of 750 to 800°C, the reaction is controlled by the diffusion and chemical reaction; at the third temperature range （800-1000°C）, the dominant controlling mechanism is diffusion.

关键词： titanium hydride aluminum reaction kinetics reaction rate constants

Geostatistical Assessment of the Spatial Distribution of Some Chemical Properties in Calcareous Soils

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2012年第10期11卷 1729-1737页

作者： Asma Najafian Mahmood Dayani hamid reza Motaghian Habibolah Nadian Department of Soil Sciences College of Agriculture Shiraz University Shiraz *** 1ran Department of Soil Sciences Khouzestan Ramin University of Agriculture and Natural Resources Ahwaz *** Iran Department of Soil Science Faculty of Agriculture Shahrekord University Shahrekord *** Iran

Spatial patterns of soil fertility parameters and other extrinsic factors need to be identified to develop farming practices that match agricultural inputs with local crop needs. Little is known about the spatial structure of nutrition in Iran. The present study was conducted in a 132-ha field located in central Iran. Soil samples were collected at 0-30 cm depth and were then analyzed for total nitrogen （N）, available phosphorus （P）, available potassium （K）, available copper （Cu）, available zinc （Zn）, available iron （Fe） and available manganese （Mn）. The results showed that the contents of soil organic matter, Cu and Zn in Marvdasht＇s farms were low. The spatial distribution model and spatial dependence level for soil chemical properties varied in the field. N, K, carbonate calcium equivalent （CaCO3） and electrical conductivity （EC） data indicated the existence of moderate spatial dependence. The variograms for other variables revealed stronger spatial structure. The results showed a longer range value for available P （480 m）, followed by total N （429 m）. The value of other chemical properties values showed a shorter range （128 to 174 m）. Clear patchy distribution of N, P, K, Fe, Mn, Cu and Zn were found from their spatial distribution maps. This proved that sampling strategy for estimating variability should be adapted to the different soil chemical properties and field management. Therefore, the spatial variability of soil chemical properties with strong spatial dependence could be readily managed and a site-specific fertilization scheme for precision farming could be easily developed.

关键词： geostatistics kriging spatial variability precision farming

Effects of chelating agents on the sol-gel synthesis of nano-zirconia:Comparison of the Pechini and sugar-based methods

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 693-702页

作者： Faramarz Kazemi Farzin Arianpour Mahdiar Taheri Ali Saberi hamid reza rezaie Department of Mining and Metallurgy Amirkabir University of TechnologyTehranIran Research and Application Center Kastamonu UniversityKastamonuTurkey College of Engineering and Computer Science The Australian National UniversityCanberraAustralia Materials Processing Faculty of Engineering ScienceUniversity of BayreuthBayreuthGermany School of Metallurgy and Materials Engineering Iran University of Science and TechnologyTehranIran

This study focused on the comparison of the Pechini and sugar-based combustion synthesis methods to produce nano-zirconia. Zirconium hydroxide was utilized as metal precursor and citric acid, sucrose, and fructose were used as chelating agents, followed by calcination at 500, 600, and 700°C in air, respectively. Characterization was conducted by thermal analysis, specific surface area measurement, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning and transmission electron microscopy. When sucrose and citric acid were used as chelating agents during synthesis, mixtures of monoclinic and tetragonal phases were formed after calcination at 600 and 700°C. In the fructose samples, the tetragonal structure was the unique characterized phase. The tetragonal parameters in the fructose samples were determined using the diffraction data and the lattice parameter ratio was proven to increase with the temperature increase. Compared with the citrate and sucrose samples, the largest specific surface area(27 m2·g-1) and smallest particle size(39.1 nm) were obtained for the fructose sample after calcination at 700°C. The study revealed the formation of single-phase stabilized tetragonal zirconia using fructose as chelating agent after calcination at 500°C, and the presence and formation mechanism of stabilized tetragonal phase were also discussed on the basis of the X-ray and electron diffraction studies.

关键词： zirconia nanopowder sol-gel sugar Pechini chelation

Statistical functions used for spatial modelling due to assessment of landslide distribution and landscape-interaction factors in Iran

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2020年第4期11卷 1257-1269页

作者： hamid reza Pourghasemi Narges Kariminejad Amiya Gayen Marko Komac Department of Natural Resources and Environmental Engineering College of AgricultureShiraz UniversityShirazIran Gorgan University of Agricultural Sciences and Natural Resources Dept.of Watershed&Arid Zone ManagementGorganIran Department of Geography University of CalcuttaKolkataIndia Faculty of Civil and Geodetic Engineering University of LjubljanaSlovenia

Landslides influence the capacity for safe and sustainable development of mountainous *** study explores the spatial distribution of and the interactions between landslides that are mapped using global positioning system(GPS) and extensive field surveys in Mazandaran Province,***-pattern assessment is undertaken using several univariate summary statistical functions,including pair correlation,spherical-contact distribution,nearest-neighbor analysis,and O-ring analysis,as well as bivariate summary statistics,and a markcorrelation *** maximum entropy method was applied to prioritize the factors controlling the incidence of landslides and the landslides susceptibility *** validation processes were considered for separated 30%data applying the ROC curves,fourfold plot,and Cohen’s kappa *** results show that pair correlation and O-ring analyses satisfactorily predicted landslides at scales from 1 to 150 *** smaller scales,from 150 to 400 m,landslides were randomly *** nearest-neighbor distribution function show that the highest distance to the nearest landslide occurred in the 355 *** spherical-contact distribution revealed that the patterns were random up to a spatial scale of 80 *** bivariate correlation functions revealed that landslides were positively linked to several linear features(including faults,roads,and rivers) at all spatial *** mark-correlation function showed that aggregated fields of landslides were positively correlated with measures of land use,lithology,drainage density,plan curvature,and aspect,when the numbers of landslides in the groups were greater than the overall average *** results of analysis of factor importance have showed that elevation(topography map scale:1:25,000),distance to roads,and distance to rivers are the most important factors in the occurrence of *** susceptibility model of landslides indicates an excellent accuracy,i.e.,the AUC value of lands

关键词： Landslide Spatial point pattern Summary statistic GIS Iran

Modeling and Analysis of Mechanization Projects of Wheat Production by GERT Networks

在线全文

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2010年第7期9卷 1078-1083页

作者： reza Abdi hamid reza Ghasemzadeh Shamsollah Abdollahpour Majid Sabzeparvar Adel Dabbag Mohamadi Nasab Faculty of Agriculture University of Tabriz Faculty of Industrial University of Science and Industry(Iran)

In crop production systems,all operations such as seed bed preparation,etc.,must be accomplished on time,if yield reduction and low quality product are to be *** all operations in mechanized cropping projects require precise scheduling,planning and *** basic approach in all scheduling techniques is to form a network of activities and events relationships that graphically portrays the sequential relations between the tasks in a *** a network would as a powerful tool available a farm manager to plan,schedule,monitor and control a *** GERT（Graphical Evaluation and Review Technique） networks have most of advantages associated with networks and available system analyst in exact evaluation of certain types of networks,in this research it was used and mechanized wheat production system was simulated,modeled and *** activities,events and path were *** showed that the network model was able to answer any statistic questions concerning with the *** models,particularly GERT networks are increasingly powerful tool for modeling,scheduling,planning,controlling,and analyzing of agricultural mechanization projects.

关键词： GERT networks mechanization project scheduling wheat

COVID-19 international outbreak and the need for a suitable estimation model: A second-order polynomial equation with constant coefficients based on imported infected cases seems inadequate

在线全文

学校读者我要写书评

暂无评论

Asian Pacific Journal of Tropical Medicine 2020年第4期13卷 185-186页

作者： hamid reza Niazkar Majid Niazkar Student Research Committee Gonabad University of Medical SciencesGonabadIran Department of Civil and Environmental Engineering Shiraz UniversityShirazIran

COVID-19 due to infections with the 2019 novel coronavirus(SARS-CoV-2)was first reported in Wuhan,Hubei Province,China in December *** to 2 March 2020,it has already spread to more than 55 countries,infected more than 85000 individuals,and yielded to about 3000 death cases[1].Due to the vigorous outbreak of COVID-19,it has become a global *** management and controlling of this worldwide threat inevitably relies on the preparedness and precise risk assessment of the future,particularly in countries that new cases have been *** this regard,estimation of new probable confirmed and death cases in the near future is crucial to health care systems of each *** a result,some researches have been conducted to address this new concern[2-4].

关键词： estimation cases precise