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Structural and dielectric properties of giant dielectric Na1/2Sm1/2Cu3Ti4O12 ceramics prepared by reactive sintering methods

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Chinese Physics B 2019年第9期28卷 359-366页

作者： h Mahfoz Kotb Department of Physics College of Science King Faisal University Department of Physics Faculty of Science Assiut University

Na0.5Sm0.5Cu3Ti4O12(NSCTO) ceramics have been prepared by reactive sintering of amorphous *** plasma sintering(SPS) for 10 min at 1025℃ and conventional sintering(CS) for 10 h at 1090℃ have been employed.X-ray diffraction measurements confirmed the pure CCTO-like phase for SPS and CS NSCTO *** SPS ceramic showed an average grain size of 500 nm, which is much smaller than that of the CS(~ 5 μm) *** impedance spectroscopy measurements revealed an electrically inhomogeneous structure in the prepared *** the resistivities of grains of both ceramic samples were in the same order of magnitude, the resistivity of grain-boundaries of the CS ceramic was three orders of magnitude greater than that of the SPS *** of the samples showed giant dielectric constant(> 10^3) over wide ranges of temperatures and ***, the room-temperature dielectric loss of the SPS NSCTO(3.2 at 1.1 khz) ceramic sample was higher than that of the CS NSCTO(0.08 at 1.1 khz) ceramic sample due to the reduced grain-boundary resistivity of the *** dielectric relaxations were detected for each sample and attributed to the relaxations in grains and *** dielectric behavior of the SPS and CS NSCTO ceramics could be interpreted in terms of the internal barrier layer capacitor(IBLC) model.

关键词： ceramics sintering dielectric loss and relaxation

Compressible closure models for turbulent multifluid mixing

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Applied Mathematics and Mechanics(English Edition) 2016年第1期37卷 97-106页

作者： h.JIN Department of Mathematics Jeju National University

This paper studies governing equations describing the turbulent fluid mixing behavior effectively. The goal is to propose a closure for compressible multiphase flow models with transport and surface tension, which satisfy the boundary conditions at the mixing zone edges, the conservation requirements, and an entropy inequality constraint. Implicitness of positivity for the entropy of averaging requires entropy inequality as op- posed to conservation of entropy for microphysically adiabatic processes.

关键词： multiphase flow closure constitutive law averaged equation

A Lyapunov-based three-axis attitude intelligent control approach for unmanned aerial vehicle

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Journal of Central South University 2015年第12期22卷 4669-4678页

作者： A.h.Mazinan Department of Control Engineering Faculty of Electrical EngineeringSouth Tehran BranchIslamic Azad University (IAU)

A novel Lyapunov-based three-axis attitude intelligent control approach via allocation scheme is considered in the proposed research to deal with kinematics and dynamics regarding the unmanned aerial vehicle *** is a consensus among experts of this field that the new outcomes in the present complicated systems modeling and control are highly appreciated with respect to *** control scheme presented here is organized in line with a new integration of the linear-nonlinear control approaches,as long as the angular velocities in the three axes of the system are accurately dealt with in the inner closed loop *** the corresponding rotation angles are dealt with in the outer closed loop *** should be noted that the linear control in the present outer loop is first designed through proportional based linear quadratic regulator(PD based LQR) approach under optimum coefficients,while the nonlinear control in the corresponding inner loop is then realized through Lyapunov-based approach in the presence of uncertainties and *** order to complete the inner closed loop control,there is a pulse-width pulse-frequency(PWPF) modulator to be able to handle on-off ***,the number of these on-off thrusters may be increased with respect to the investigated control efforts to provide the overall accurate performance of the system,where the control allocation scheme is realized in the proposed *** may be shown that the dynamics and kinematics of the unmanned aerial vehicle systems have to be investigated through the quaternion matrix and its corresponding vector to avoid presenting singularity of the *** the end,the investigated outcomes are presented in comparison with a number of potential benchmarks to verify the approach performance.

关键词： Lyapunov based control approach PD based LQR approach control allocation scheme kinematics and dynamics unmanned aerial vehicle system on-off thrusters PWPF modulator

Application of hybrid robust three-axis attitude control approach to overactuated spacecraft——A quaternion based model

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Journal of Central South University 2016年第7期23卷 1740-1753页

作者： A.h.Mazinan Department of Control Engineering Faculty of Electrical Engineering South Tehran BranchIslamic Azad University(IAU)

A novel hybrid robust three-axis attitude control approach, namely hRTAC, is considered along with the well-known developments in the area of space systems, since there is a consensus among the related experts that the new insights may be taken into account as decision points to outperform the available materials. It is to note that the traditional control approaches may generally be upgraded, as long as a number of modifications are made with respect to state-of-the-art, in order to propose high-precision outcomes. Regarding the investigated issues, the robust sliding mode finite-time control approach is first designed to handle three-axis angular rates in the inner control loop, which consists of the pulse width pulse frequency modulations in line with the control allocation scheme and the system dynamics. The main subject to employ these modulations that is realizing in association with the control allocation scheme is to be able to handle a class of overactuated systems, in particular. The proportional derivative based linear quadratic regulator approach is then designed to handle three-axis rotational angles in the outer control loop, which consists of the system kinematics that is correspondingly concentrated to deal with the quaternion based model. The utilization of the linear and its nonlinear terms, simultaneously, are taken into real consideration as the research motivation, while the performance results are of the significance as the improved version in comparison with the recent investigated outcomes. Subsequently, there is a stability analysis to verify and guarantee the closed loop system performance in coping with the whole of nominal referenced commands. At the end, the effectiveness of the approach considered here is highlighted in line with a number of potential recent benchmarks.

关键词： three-axis angular rates and rotations sliding mode finite-time control approach proportional derivative based linearquadratic regulator approach dynamics and kinematics of overactuated spacecraft

Bio-fluid flow analysis based on heat transfer and variable viscosity

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Applied Mathematics and Mechanics(English Edition) 2019年第7期40卷 1029-1040页

作者： h.SADAF Department of Basic Sciences and humanities College of Electrical and Mechanical EngineeringNational University of Sciences and TechnologyIslamabad

This study investigates the cilia transport phenomenon from the perspectives of the heat transfer and variable viscosity in a bending channel. The rightward wall is maintained at a temperature of T0, and the leftward wall has a temperature of T1. Each wall has a metachronal wave that travels along its wall. The structures of the ciliary assemblies are calculated by the well-known simplifying suppositions of the large wavelength and the small Reynolds number approximation. The flow phenomenon for the Newtonian fluid is described as a function of cilia and a metachronal wave velocity. The pressure rise is calculated with MAThEMATICA. The theme of the cilia beating flow is inspected with scheming plots, and its features are discussed at the end of the article.

关键词： cilia-driven flow curved channel temperature dependent viscosity metachronal wave heat transfer exact solution

Two-Dimensional Linear Dependencies on the Coordinate Time-Dependent Interaction in Relativistic Non-Commutative Phase Space

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Communications in Theoretical Physics 2015年第9期64卷 263-268页

作者： h.Sobhani h.hassanabadi Physics Department University of Shahrood

In this paper, the Non-Commutative phase space and Dirac equation, time-dependent Dirac oscillator are introduced. After presenting the desire general form of a two-dimensional linear dependency on the coordinate timedependent potential, the Dirac equation is written in terms of Non-Commutative phase space parameters and solved in a general form by using Lewis–Riesenfield invariant method and the time-dependent invariant of Dirac equation with two-dimensional linear dependency on the coordinate time-dependent potential in Non-Commutative phase space has been constructed, then such latter operations are done for time-dependent Dirac oscillator. In order to solve the differential equation of wave function time evolution for Dirac equation and time-dependent Dirac oscillator which are partial differential equation some appropriate ordinary physical problems have been studied and at the end the interesting result has been achieved.

关键词： Non-Commutative phase space Dirac equation time-de

Perception of dental appearance and aesthetic analysis among patients,laypersons and dentists

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World Journal of Clinical Cases 2024年第23期12卷 5354-5365页

作者： Alhanoof Aldegheishem hadeel Mohammed Alfayadh Munirah AlDossary Shahad Asaad Elzahraa Eldwakhly Nour AL huda AL Refaei Dana Alsenan Mai Soliman Department of Clinical Dental Sciences College of DentistryPrincess Nourah Bint Abdulrahman UniversityRiyadh 11671Saudi Arabia Department of Oral Medicine and Pathology Ministry of HealthRiyadh 11176Saudi Arabia Department of Prosthodontics Ministry of HealthRiyadh 11176Saudi Arabia Department of Pediatric Ministry of HealthRiyadh 11176Saudi Arabia

BACKGROUND Current concepts of beauty are increasingly subjective,influenced by the viewpoints of *** aim of the study was to evaluate divergences in the perception of dental appearance and smile esthetics among patients,laypersons and dental *** study goals were to evaluate the influence of age,sex,education and dental specialty on the participants’judgment and to identify the values of different esthetic *** sample included 50 patients who responded to a dental appearance questionnaire(DAQ).Two frontal photographs were taken,one during a smile and one with retracted *** and dentists were asked to evaluate both photographs using a Linear Scale from(0-10),where 0 represent(absolutely unaesthetic)and 10 represent(absolutely aesthetic).One-way analysis of variance(ANOVA)and t-test analysis were measured for each *** patients in the sample expressed satisfaction with most aspects of their smiles and dental *** laypersons(including 488 participants),47 pictures“with lips”out of 50 had higher mean aesthetic scores compared to pictures“without lips”.Among the dentist sample,90 dentists’perception towards the esthetic smile and dental appearance for photos“with lips”and“without lips”were the same for 23 out of 50 *** of smile aesthetics differed between patients,laypersons and *** factors can contribute to shape the perception of smile *** To compare the perception of dental aesthetic among patients,laypersons,and professional dentists,to evaluate the impact of age,sex,educational background,and income on the judgments made by laypersons,to assess the variations in experience,specialty,age,and sex on professional dentists’judgment,and to evaluate the role of lips,skin shade and tooth shade in different participants’*** Patients sample included 50 patients who responded to *** frontal photographs were taken:one during a smile and one with retracted lip

关键词： Aesthetic perception Laypersons Dental appearance Dentists Smile analysis Dental aesthetic

Fore-aft asymmetry of the ~2h(n,γ)~3h at very low energies

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Chinese Physics C 2013年第9期37卷 13-18页

作者： h.Khalili h.Sadeghi Department of Physics Faculty of ScienceArak University

We have used the recent effective field theory （EFT） which is constructed from two- and three-nucleon interactions, using minimal substitution in the momentum dependence of these interactions. We present the calcula- tions of the fore-aft asymmetry of γ-rays in the reaction 2h（n,γ）3h which are based on EFT up to next-to-next-to leading order （N2LO）. The results are compared with the recently reported calculations and measurements of the fore-aft asymmetry of T-rays from neutron-deuteron radiative capture. The calculated fore-aft asymmetry of the nd radiative capture process above deuteron breakup threshold is in good agreement with the available experimental data up to 20 MeV.

关键词： effective field theory neutron-deuteron radiative capture photonuclear observables fore-aft asymmetry

Relations between SMBh Parameters and Jet Generation and Efficiency in Blazars

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Research in Astronomy and Astrophysics 2023年第11期23卷 67-83页

作者： h.Zhang h.J.Zhang Department of Physics Yunnan Normal UniversityKunming 650092China

We analyzed the relationship between several basic parameters describing supermassive black holes such as jet power,black hole spin,accretion disk magnetic field,black hole mass,*** found that there is a general correlation between these parameters,such as jet power is significantly positively correlated with black hole spin,while black hole mass is significantly negatively correlated with black hole *** apprehend these relationships,we consider the Blandford–Znajek model to be superior to the Blandford–Payne *** is also found that the intrinsic gamma luminosity of the FSRQs has a positive correlation with the accretion disk magnetic field,while the intrinsic gamma luminosity of the BL Lacs has a negative correlation with the accretion disk magnetic field.A feedback effect may exist between accretion disk accretion rate and magnetic field,which may be the key to the evolution between BL Lacs and *** is no significant difference in the jet power and jet generation efficiency of FSRQs and BL Lacs,which suggests that the jets are generated by the same *** contribution rate of accretion rate to jet generation efficiency is high,while the contribution rate of accretion rate to jet power is very low.

关键词： galaxies:evolution galaxies:fundamental parameters galaxies:jets