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Approximation of structural damping and input excitation force

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Frontiers of Structural and Civil Engineering 2017年第2期11卷 244-254页

作者： mohammad SALAVATI Institute of Structural Mechanics Faculty of Civil Engineering Bauhaus University Weimar Weimar 99423 Germany

Structural dynamic characteristics are the most significant parameters that play a decisive role in structural damage assessment. The more sensitive parameter to the damage is the damping behavior of the structure. The complexity of structural damping mechanisms has made this parameter to be one of the ongoing research topics. Despite all the difficulties in the modeling of damping, there are some approaches like as linear and nonlinear models which are described as the energy dissipation throughout viscous, material or structural hysteretic and frictional damping mechanisms. In the presence of a mathematical model of the damping mechanisms, it is possible to estimate the damping ratio from the theoretical comparison of the damped and un-damped systems. On the other hand, solving the inverse problem of the input force estimation and its distribution to each SDOFs, from the measured structural responses plays an important role in structural identification process. In this paper model-based damping approximation method and a modelless structural input estimation are considered. The effectiveness of proposed methods has been carded out through analytical and numerical simulation of the lumped mass system and the results are compared with reference data. Consequently, high convergence of the comparison results illustrates the satisfactory of proposed approximation methods.

关键词： structural modal parameters damping identification method input excitation force identification Inverse problem

Electronic and mechanical responses of two-dimensional HfS2,HfSe2,ZrS2,and ZrSe2 from first-principles

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Frontiers of Structural and Civil Engineering 2019年第2期13卷 486-494页

作者： mohammad SALAVATI Institute of Structural Mechanics Bauhaus-Universitat WeimarD-99423 WeimarGermany

During the last decade, numerous high-quality two-dimensional (2D) materials with semiconducting electronic character have been synthesized. Recent experimental study (Sci. Adv. 2017;3: el700481) nevertheless confirmed that 2D ZrSe2 and HfSe2 are among the best candidates to replace the silicon in nanoelectronics owing to their moderate band-gap. We accordingly conducted first-principles calculations to explore the mechanical and electronic responses of not only ZrSe2 and HfSe2, but also ZrS? and HfS? in their single-layer and free-standing form. We particularly studied the possibility of engineering of the electronic properties of these attractive 2D materials using the biaxial or uniaxial tensile loadings. The comprehensive insight provided concerning the intrinsic properties of HfS2, HfSe2, ZrS2, and ZrSc? can be usefiil for their future applications in nanodevices.

关键词： 2D materials mechanical electronic DFT

Predicting minimum fluidization velocities of multi-component solid mixtures

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Particuology 2013年第3期11卷 309-316页

作者： mohammad Asif Chemical Engineering Department King Saud University

Employing well-established mixing rules for mean properties, appropriate expressions are derived for predicting minimum fluidization velocities of multi-component solid mixtures in terms of mono- component values for the velocity and the bed voidage at incipient fluidization. Based on flow regime and the mixing level of constituent species, it is found that these relationships differ significantly from each other, whether related to size-different or density-different mixtures. For mixed beds of size-different mixtures, the effect of volume contraction is accounted for by the mean voidage term, which is absent for segregated beds. Incorporating the volume-change of mixing leads to values of the mixture minimum fluidization velocities even lower than corresponding values for segregated bed, thus conforming to the trend reported in the literature. Size-different mixtures exhibit flow regime dependence irrespective of whether the bed is mixed or segregated. On the other hand, the mixing of constituent species does not affect the minimum fiuidization velocity of density-different mixtures, as the difference in the expres- sions for a segregated and a mixed system is rather inconsequential. Comparison with experimental data available in the literature is made to test the efficacy of the minimum fluidization velocity expressions derived here.

关键词： Minimum fluidization velocity Multi-component solid mixtures Flow regime Bed void fraction Volume-change of mixing

A Simplified Model, Dynamic Analysis and Force Estimation for a Large-scale Orinthopter in Forward Flight Based on Flight Data

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Journal of Bionic Engineering 2020年第5期17卷 989-1008页

作者： mohammad Ali Amini Moosa Ayati mohammad Mahjoob School of Mechanical Engineering College of EngineeringUniversity of TehranNorth Kargar StreetTehranIran

Similarities and differences of a large-scale flapping-wing robot with fixed-wing UAVs in equations of motion,trim curves,and aerodynamic forces in forward flight are discussed in this paper and a simplified model for flapping flight is *** to the high Wing to Total Weight(WTW)ratio of large-scale omithopters,simple rigid body dynamics is not accurate enough for flight dynamics *** the other hand,the multi-body dynamics associated with flapping gives little insight into the behavior of the resulting model due to complexity of *** is also difficult to design proper controllers for such complicated *** this paper,the effects of different terms of multi-body equations of ornithopter on the estimated aerodynamic forces are studied via experimental flight data.A simpler but yet accurate set of equations is obtained by removing less effective terms from original *** presented model is in the form of normal aircraft equations plus some additional terms which can be used in different control and estimation *** addition,trim conditions of forward flight are extracted using several flight tests,and corresponding periodic behavior of states and forces are *** studies are applicable for identifying time-periodic models.

关键词： flapping wing robot bionic robot ornithopter trim condition analysis low-order modeling aerodynamic force estimation

Determination of hemoglobin adduct of a musk xylene metabolite in trout as biomarker of exposure by gas chromatography mass spectrometry

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Journal of Environmental Sciences 2005年第6期17卷 989-992页

作者： mohammad Abdul KARIM mohammad Rezaul Department of Chemistry and Biochemistry Baylor University P.O. Box 97348 Waco TX 76798-7348 USADepartment of Biochemistry and Molecular Biology University of Rajshahi Rajshahi 6205 Bangladesh

Musk xylene（MX） is frequently used as fragrances in formulation of personal care products. Quantification of a bound 4-amino- MX（4-AMX） as cysteine adducts in trout hemoglobin（Hb） was made by gas chromatography-ion trap-mass spectrometry（GC/MS）. The Hb samples were collected from trout after 24 h exposure to MX at 10μg/g, and or menhaden oil（control）. The formation of cysteine-Hb adduct was observed from nitroso derivative of MX, released by alkaline hydrolysis. The released 4-AMX metabolite was extracted in n- hexane. The extract was then reduced by evaporation, and analyzed by GC/MS. When similar agreement of mass spectral features and retention time of 4-AMX were obtained in both standard and sample solutions, the presence of 4-AMX metabolite in the Hb was confirmed. The concentration of 4-AMX was found to be 3.1 × 10^-6 6.9 × 10^-6 mg/g in the Hb solution. Quantitation was made based on an internal standard, a calibration plot, and response factor. In the non-hydrolyzed and laboratory blank extracts, the 4-AMX metabolite was not detected. Additionally, coeluting and interfefing ions were observed in the biological samples.

关键词： biomarkers musk xylene metabolite Hb adducts fish exposure

Leptopsylla algira costai(Siphonaptera:Leptopsyllidae):New host and new geographical record

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Journal of Coastal Life Medicine 2016年第12期4卷 953-954页

作者： Ali Yousefi mohammad Naser Ghorbani sadegh Salehi-Guilandeh Young Researchers and Elites Club Science and Research BranchIslamic Azad UniversityTehranIran Department of Microbiology Science and Research BranchIslamic Azad UniversityTehranIran Department of Pathobiology School of Veterinary ScienceBu-Ali Sina UniversityHamedanIran

Objective:To access the emerging ectoparasites associated with shrews in Hamedan Province of ***:We have captured bicoloured white-toothed shrews[Crocidura leucodon(***)]using the live traps in April *** collected by brushing the skins were removed and preserved in 70%ethanol containing 5%glycerin,and subsequently they were sent to the parasitology laboratory and *** fleas isolated from infested specimen were cleared in 10%aqueous potassium hydroxide,dehydrated in ethanol,cleared in xylene,mounted in Canada balsam and identified using reliable ***:In general,eight fleas(one male,seven females)were collected from *** in Hamedan Province,Western *** fleas were identified as Leptopsylla algira costai Smit,***:Fleas are medically important because they transmit a wide variety of diseases to their *** addition,this aricle reports Leptopsylla algira costai for the first time in new host(***)and new geographical region(Iran).

关键词： Flea Siphonaptera Parasite Crocidura leucodon Iran

Experimental investigation of different brines imbibition influences on co-and counter-current oil flows in carbonate reservoirs

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Chinese Journal of Chemical Engineering 2021年第5期34卷 17-29页

作者： Pouyan Ahmadi mohammad Reza Aghajanzadeh Masoud Riazi mohammad Reza Malayeri mohammad Sharifi Enhanced Oil Recovery(EOR)Research Centre IOR/EOR Research InstituteShiraz UniversityShirazIran Helmholtz Centre for Environmental Research-UFZ LeipzigGermany Department of Petroleum Engineering Amirkabir University of TechnologyTehranIran Institut für Verfahrenstechnik und Umwelttechnik Technische Universität DresdenGermany

Imbibition of water,as wetting phase in oil-wet fractured carbonate reservoirs,plays a key role in fluid flow between matrix and fracture *** type of injected seawater and its chemistry would profoundly influence the imbibition *** this study,the impact of smart water(a brine that its ions have been adjusted to facilitate oil recovery)and low salinity water on co-and counter-current imbibition processes for oil-wet carbonate cores has been experimentally *** results show an increase of about 10% in oil recovery for co-and counter-currents for smart seawater imbibition compared to that of low salinity *** addition,as a result of the influence of co-and counter-current on each other,by co-current removal from one core face,the countercurrent in the other face would be intensified by as much as about 75%.A close examination of different lengths(5,7 and 9 cm)of carbonate cores with the same permeability revealed that by decreasing porous medium length,the amount of counter-current producing oil would be decreased so that in the 5 cm core,counter current oil production will not *** similar core lengths by increasing permeability,the share of counter current flow would be decreased approximately 18% since the capillary pressure could not overcome non-wetting phase viscous *** the role of matrix length along with a modified brine(which is designed according to the matrix mixture)strengthen the relevant mechanisms to have more oil production so that the higher thickness of matrix causes the higher amount of co-current oil producing and consequently more total recovery.

关键词： Smart water Co-current Counter current Wettability alteration Oil recovery

Mineralogical and sink-float studies of Jajarm low-grade bauxite

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International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 251-256页

作者： mohammad Zarbayani Esmaeil Jorjani Mirsaleh Mirmohammadi mohammad Taghi Shadloo mohammad Noaparast Science and Research Branch Islamic Azad University School of Mining Engineering University of Tehran Jajarm Alumina Company

Jajarm＇s bauxite deposits are mainly diasporic, and they have a low mass ratio of Al2O3/SiO2. It is necessary to increase the run-of-mine mass ratio before feeding the material to the Bayer process. Chemical analysis indicated that the low-grade bauxite sample from Jajarm contained 43.9wt% Al2O3 and 13.35wt% SiO2, resulting in a mass ratio of 3.29. According to mineralogical studies, the presence of aluminosilicate minerals such as kaolinite, illite, and quartz was the main reason for the decrease of the mass ratio. Microscopic observations revealed that, with the size reduction from -1000＋710 to -38 μm, the liberation degree of diaspore increased from 10% to 60%, and that of aluminosilicates increased from 20% to 85%. Heavy liquids with the densities of 2.8, 3.0, 3.2, and 3.4 g/cm3 were used to evaluate the heavy media separation in three sizes, i.e., -3350＋710, -710＋212, and -212＋125 μm. Laboratory studies confirm that the density of 3.2 g/cm3 can produce the concentrates （in sunk fractions） with recoveries of 89.09%, 91.24%, and 84.68% with the Al2O3/SiO2 mass ratios of 5.03, 5.16, and 5.15 for the -3350＋710, -710＋212, and -212＋ 125 μ m sizes, respectively.

关键词： bauxite diaspore aluminosilicate mass ratio heavy media

Carbon mineralization in subtropical alluvial arable soils amended with sugarcane bagasse and rice husk biochars

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Pedosphere 2022年第3期32卷 475-486页

作者： mohammad Arifur RAHMAN mohammad Abdul KADER mohammad JAHIRUDDIN mohammad Rafiqul ISLAM Zakaria mohammad SOLAIMAN Regional Agricultural Research Station(RARS) Bangladesh Agricultural Research Institute(BARI)Jamalpur 2000(Bangladesh) School of Agriculture GeographyEnvironmentOcean and Natural SciencesUniversity of South PacificApia 1343(Samoa) Department of Soil Science Bangladesh Agricultural University(BAU)Mymensingh 2202(Bangladesh) UWA School of Agriculture&Environment and the UWA Institute of Agriculture PerthWA 6009(Australia) School of Veterinary and Life Science Murdoch UniversityMurdochWA 6150(Australia)

Subtropical recent alluvial soils are low in organic carbon(C).Thus,increasing organic C is a major challenge to sustain soil *** amendment could be an option as biochar is a C-rich pyrolyzed material,which is slowly decomposed in *** investigated C mineralization(CO_(2)-C evolution)in two types of soils(recent and old alluvial soils)amended with two feedstocks(sugarcane bagasse and rice husk)(1%,weight/weight),as well as their biochars and aged biochars under a controlled environment(25±2℃)over 85 *** the recent alluvial soil(charland soil),the highest absolute cumulative CO_(2)-C evolution was observed in the sugarcane bagasse treatment(1140 mg CO_(2)-C kg^(-1)soil)followed by the rice husk treatment(1090 mg CO_(2)-C kg^(-1)soil);the lowest amount(150 mg CO_(2)-C kg^(-1)soil)was observed in the aged rice husk biochar ***,for the old alluvial soil(farmland soil),the highest absolute cumulative CO_(2)-C evolution(1290 mg CO_(2)-C kg^(-1)soil)was observed in the sugarcane bagasse treatment and then in the rice husk treatment(1270 mg CO_(2)-C kg^(-1)soil);the lowest amount(200 mg CO_(2)-C kg^(-1)soil)was in the aged rice husk biochar *** sugarcane bagasse and rice husk biochar treatments reduced absolute cumulative CO_(2)-C evolution by 10%and 36%,respectively,compared with unamended recent alluvial soil,and by 10%and 18%,respectively,compared with unamended old alluvial *** absolute and normalized C mineralization were similar between the sugarcane bagasse and rice husk treatments,between the biochar treatments,and between the aged biochar *** both soils,the feedstock treatments resulted in the highest cumulative CO_(2)-C evolution,followed by the biochar treatments and then the aged biochar *** absolute and normalized CO_(2)-C evolution and the mineralization rate constant of the stable C pool(K_(s))were lower in the recent alluvial soil compared with those in the old alluvial *** biochar

关键词： aged biochar biochar amendment charland CO_(2)emission CO_(2)-C evolution recent alluvial soil soil organic carboon soil organic matter