检索结果-南通市图书馆

Combining the 8-hydroxyquinoline intercalated layered double hydroxide film and sol-gel coating for active corrosion protection of the magnesium alloy

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2022年第3期29卷 536-546页

作者： Yahya jafari Tarzanagh Davod Seifzadeh Roghaye Samadianfard Applied Chemistry Department University of Mohaghegh ArdabiliArdabil ***Iran

8-hydroxyquinoline(8-HQ)intercalated layered double hydroxides(LDH)film as underlayer and sol-gel layer was combined for active corrosion protection of the AM60B magnesium *** LDH,LDH/sol-gel,and LDH@HQ/sol-gel coatings were analyzed using the scanning electron microscopy(SEM),field emission scanning electron microscopy(FESEM),energy dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD),atomic force microscopy(AFM),and electrochemical impedance spectroscopy(EIS)*** SEM images showed that the surface was entirely coated by the LDH film composed of vertically-grown *** same morphology was observed for the LDH/sol-gel and LDH@HQ/sol-gel ***,almost the same topography was observed for both composite coatings except that the LDH@HQ/sol-gel coating had relatively higher surface *** the LDH film had the same impedance behavior as the alloy sample in 3.5wt%NaCl solution,its corrosion resistance was much higher,which could be due to its barrier properties as well as to the trap-ping of the chloride *** to the LDH film,the corrosion resistance of the LDH/sol-gel composite diminished with increasing the ex-posure ***,its values were much higher than that of the LDH film,which was mainly related to the sealing of the solution *** LDH@HQ/sol-gel composite showed much better anti-corrosion properties than the LDH/sol-gel coating due to the adsorption of the 8-HQ on the damaged areas through the complexation.

关键词： magnesium alloy sol-gel layered double hydroxides corrosion coating

Pile end bearing capacity in rock mass using cavity expansion theory

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2020年第5期12卷 1103-1111页

作者： Haythem Gharsallaoui Mustafa jafari Alain Holeyman Department of Civil and Environmental Engineering(GCE) Institute of MechanicsMaterials and Civil engineering(iMMC)UniversitéCatholique de Louvain(UCLouvain)Louvain-la-NeuveBelgium

Much empiricism is involved in design of rock-socketed piles in rock *** light of this,an analytical solution based on the cavity expansion theory is proposed for calculating the ultimate bearing capacity at the tip of a pile embedded in rock masses obeying the Hoek-Brown failure *** ultimate end bearing capacity is evaluated by assuming that the pressure exerted at the boundaries of a pressure bulb immediately beneath the pile tip is equal to the limit pressure required to expand a spherical *** addition,a relationship is derived to predict the pile load-settlement *** demonstrate the applicability of the presented solution,the results of this study were compared to those of 91 field tests from technical *** the limitations,it is found that the end bearing resistance computed by the present work is in good agreement with the field test results.

关键词： Hoek-Brown failure criterion Spherical cavity Limit pressure End bearing capacity

Three-dimensional simulation of long-wavelength free-electron lasers with helical wiggler and ion-channel guiding

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2013年第7期22卷 183-191页

作者： F. jafari Bahman B. Maraghechi Department of Physics Amirkabir University of Technology

A three-dimensional simulation of a steady-state amplifier model of a long-wavelength free-electron laser （FEL） with realizable helical wiggler and ion-channel guiding is presented. The set of coupled nonlinear differential equations for electron orbits and fields of TE 11 mode in a cylindrical waveguide are solved numerically by the Runge–Kutta algorithm with averages calculated by the Gaussian quadrature technique. Self-fields and space-charge effects are neglected, and the electron beam is assumed to be cold and slippage is ignored. The parameters correspond to the Compton regime. Evolution of the radiation power and growth rate along the wiggler is studied. Ion-channel density is chosen to obtain optimum efficiency. Simulations are preformed for the FEL operating in the neighborhood of 35 GHz and 16.5 GHz for the electron beam energies of 250 keV and 400 keV, respectively. The result of the saturated efficiency was found to be in good agreement with the simple estimation based on the phase-trapping model.

关键词： free-electron laser helical wiggler ion-channel guiding

BANACH SPACES AND INEQUALITIES ASSOCIATED WITH NEW GENERALIZATION OF CESàRO MATRIX

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2023年第4期43卷 1518-1536页

作者： Feyzi BASAR hadi ROOPAEI Department of Primary Mathematics Teacher Education Inonu University44280–MalatyaTurkiye Department of Mathematics and Statistics University of VictoriaVictoriaCanada

Let the triangle matrix A^(ru)be a generalization of the Cesàro matrix and U∈{c_(0),c,l_(∞)}.In this study,we essentially deal with the space U(A^(ru))defined by the domain of A^(ru)in the space U and give the bases,and determine the Kothe-Toeplitz,generalized K?theToeplitz and bounded-duals of the space U(A^(ru)).We characterize the classes(l_(∞)(A^(ru)):l_(∞)),(l_(∞)(A^(ru)):c),(c(A^(ru)):c),and(U:V(A^(ru)))of infinite matrices,where V denotes any given sequence ***,we also present a Steinhaus type *** an another result of this study,we investigate the l_(p)-norm of the matrix A^(ru)and as a result obtaining a generalized version of Hardy's inequality,and some inclusion ***,we compute the norm of well-known operators on the matrix domain l_(p)(A^(ru)).

关键词： matrix domain normed sequence space duals and matrix transformations

Laser-Plasma Interaction in Presence of an Obliquely External Magnetic Field:Application to Laser Fusion without Radioactivity

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2016年第8期65卷 237-243页

作者： M.Mobaraki S.jafari Department of Physics University of Guilan

In this paper, the nonlinear interaction of ultra-high power laser beam with fusion plasma at relativistic regime in the presence of obliquely external magnetic field has been studied. Imposing an external magnetic field on plasma can modify the density profile of the plasma so that the thermal conductivity of electrons reduces which is considered to be the decrease of the threshold energy for ignition. To achieve the fusion of Hydrogen–Boron(HB) fuel,the block acceleration model of plasma is employed. Energy production by HB isotopes can be of interest, since its reaction does not generate radioactive tritium. By using the inhibit factor in the block model acceleration of plasma and Maxwell's as well as the momentum transfer equations, the electron density distribution and dielectric permittivity of the plasma medium are obtained. Numerical results indicate that with increasing the intensity of the external magnetic field, the oscillation of the laser magnetic field decreases, while the dielectric permittivity increases. Moreover, the amplitude of the electron density becomes highly peaked and the plasma electrons are strongly bunched with increasing the intensity of external magnetic field. Therefore, the magnetized plasma can act as a positive focusing lens to enhance the fusion process. Besides, we find that with increasing θ-angle(from oblique external magnetic field) between 0 and 90°, the dielectric permittivity increases, while for θ between 90° and 180°, the dielectric permittivity decreases with increasing θ.

关键词： laser-plasma interaction external magnetic field laser fusion HB fuel

New ordered MAX phase Mo_2 TiAlC_2: Elastic and electronic properties from first-principles

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第10期25卷 323-329页

作者： M A hadi M S Ali Department of Physics University of Rajshahi Department of Physics Pabna University of Science and Technology

First-principles computation on the basis of density functional theory(DFT) is executed with the CASTEP code to explore the structural, elastic, and electronic properties along with Debye temperature and theoretical Vickers’ hardness of newly discovered ordered MAX phase carbide Mo2TiAlC2. The computed structural parameters are very reasonable compared with the experimental results. The mechanical stability is verified by using the computed elastic constants. The brittleness of the compound is indicated by both the Poisson’s and Pugh’s ratios. The new MAX phase is capable of resisting the pressure and tension and also has the clear directional bonding between atoms. The compound shows significant elastic anisotropy. The Debye temperature estimated from elastic moduli(B, G) is found to be 413.6 K. The electronic structure indicates that the bonding nature of Mo2TiAlC2is a mixture of covalent and metallic with few ionic characters. The electron charge density map shows a strong directional Mo–C–Mo covalent bonding associated with a relatively weak Ti–C *** calculated Fermi surface is due to the low-dispersive Mo 4d-like bands, which makes the compound a conductive *** hardness of the compound is also evaluated and a high value of 9.01 GPa is an indication of its strong covalent bonding.

关键词： new ordered MAX phase density functional theory calculations Debye temperature Vickers hardness

An automatic subdigraph renovation plan for failure recovery of composite semantic Web services

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2013年第6期7卷 894-913页

作者： hadi SABOOHI Sameem ABDUL KAREEM Department of Artificial Intelligence Faculty of Computer Science and Information Technology University of Malaya Kuala Lumpur 50603 Malaysia

A Web service-based system never fulfills a user＇s goal unless a failure recovery approach exists. It is inevitable that several Web services may either perish or fail before or during transactions. The completion of a composite process relies on the smooth execution of all constituent Web services. A mediator acts as an intermediary between providers and consumers to monitor the execution of these services. If a service fails, the mediator has to recover the whole composite process or else jeopardize achieving the intended goals. The atomic replacement of a perished Web service usually does not apply because the process of locating a matched Web service is unreliable. Even the system cannot depend on the replacement of the dead service with a com- posite service. In this paper, we propose an automatic renova- tion plan for failure recovery of composite semantic services based on an approach of subdigraph replacement. A replacement subdigraph is posed in lieu of an original subdigraph, which includes the failed service. The replacement is done in two separate phases, ofltine and online, to make the recovery faster. The ofitine phase foresees all possible subdigraphs, pre-calculates them, and ranks several possible replacements. The online phase compensates the unwanted effects and executes the replacement subdigraph in lieu of the original subdigraph. We have evaluated our approach during an experiment and have found that we could recover more than half of the simulated failures. These achievements show a significant improvement compared to current approaches

关键词： semantic Web service composite services fail- ure recovery subdigraph replacement

Nonlinear vibration analysis of laminated composite Mindlin micro/nano-plates resting on orthotropic Pasternak medium using DQM

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2015年第8期36卷 1033-1044页

作者： A.G.ARANI G.S.jafari Faculty of Mechanical Engineering University of Kashan Institute of Nanoscience & Nanotechnology University of Kashan

The nonlocal nonlinear vibration analysis of embedded laminated micro- plates resting on an elastic matrix as an orthotropic Pasternak medium is investigated. The small size effects of micro/nano-plate are considered based on the Eringen nonlocal theory. Based on the orthotropic Mindlin plate theory along with the von Kármán geo- metric nonlinearity and Hamilton＇s principle, the governing equations are derived. The differential quadrature method （DQM） is applied for obtaining the nonlinear frequency of system. The effects of different parameters such as nonlocal parameters, elastic me- dia, aspect ratios, and boundary conditions are considered on the nonlinear vibration of the micro-plate. Results show that considering elastic medium increases the nonlinear frequency of system. F^lrthermore, the effect of boundary conditions becomes lower at higher nonlocal parameters.

关键词： nonlinear vibration laminated micro-plate orthotropic Pasternak medium,differential quadrature method

A novel model-based multivariable framework for aircraft gas turbine engine limit protection control

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2021年第12期34卷 57-72页

作者： Shuwei PANG Soheil jafari Theoklis NIKOLAIDIS Qiuhong LI Jiangsu Province Key Laboratory of Aerospace Power System Nanjing University of Aeronautics and AstronauticsNanjing 210016China Propulsion Engineering Center School of AerospaceTransport and ManufacturingCranfield UniversityBedford MK43 OALUK

Control technologies are innovated to satisfy increasingly complicated control demands of gas turbine *** terms of limit protection control,a novel model-based multivariable limit protection control method,which is achieved by adaptive command reconstruction and multiplecontrol loop selection and switch logic,is proposed in this paper to address the problem of balancing smaller thrust loss and safe operations by comparing with widely-used Min-Max *** different combination modes of control loops,which represent the online control loop of last time instant and that of current time instant,is *** command reconstructions are designed for these modes,which is based on static gain conversion of amplitude beyond limits by using an onboard *** double-prediction based control loop selection and switch logic is developed to choose a control loop appropriately by comparing converted amplitude beyond limits regardless of one or more parameters tending to exceed *** proposed method is implemented in a twin-spool turbofan engine to achieve limit protection with direct thrust control,and the loss of thrust is improved by about 30% in comparison with the loss of thrust caused by Min-Max logic when limit protection control is activated,which demonstrates the effectiveness of the proposed method.

关键词： Amplitude conversion Command reconstruction Gas turbine engine Limit protection control Multivariable control Onboard prediction