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Facile synthesis of samarium and cerium doped double perovskite cobaltite with enhanced dielectric response

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Journal of Rare Earths 2024年第7期42卷 1317-1327,I0005页

作者： Yasir abbas M.kamran M.Anis-ur-Rehman Applied Thermal Physics Laboratory Department of PhysicsCOMSATS University IslamabadIslamabad 45550Pakistan

The investigation of Sm-Ce doping on structure,conduction,and dielectric response of Bi_(2)Ca_(2-2x)Sm_(x)CexCoO_(6)(x=0.000,0.025,0.050,0.075)(BCSCCO)are *** the specimens were synthesized by a facile synthesis technique named the co-precipitation route.X-ray diffraction(XRD)reveals that BCSCCO crystallizes into one phase with space group P21/*** crystallite size,dislocation density,lattice parameters,lattice strain,unit cell volume,and bulk density were determined using XRD *** structural properties of Bi_(2)Ca_(2)CoO_(6)were examined using calculations based on the density functional *** and experimental values discrepancy is less than 1%.A scanning electron microscope was used for performing a microstructural *** SEM images demonstrate the homogeneous distribution of grains with a range of sizes(0.054-0.090μm).The alternating current(ac)conductivity,dielectric permittivity,and tangent loss were also studied as a function of frequency(20 Hz-3 MHz)at different temperatures(100-500℃).All synthesized samples were examined using non-linear Debye's function to determine their spreading factor and relaxation *** specimen with the lowest crystallite size(∼23 nm)exhibits a high dielectric permittivity(∼3.80×10^(6)).The conduction mechanism was examined in the studied samples with the use of Jonscher's power *** power law indicates that the BCSCCO(x=0.000,0.025)follows correlated barrier hopping,whereas the x=0.050 and 0.075 compositions follow non-overlapping polaron *** studied specimen Bi_(2)Ca_(1.9)0Sm_(0.05)0Ce_(0.05)_(0)CoO_(6)with the highest density(∼5.65 g/cm^(3))displays a high electrical conductivity(∼46.1 S/cm).These findings correspond to those published for ceramics made from calcium cobaltite using solid-state reactions(5.0-26.0 S/cm).

关键词： Bismuth calcium samarium cerium cobaltite (BCSCCO) Spreading factor Conduction mechanism Rare earths

AI-Driven Energy Optimization in UAV-Assisted Routing for Enhanced Wireless Sensor Networks Performance

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Computers, Materials & Continua 2024年第9期80卷 4085-4110页

作者： Syed kamran Haider abbas Ahmed Noman Mujeeb Khan Ali Nauman Sung Won Kim College of Internet of Things(IoT)Engineering Hohai UniversityChangzhou213001China Department of Electrical and Electronics Engineering Beaconhouse International CollegeIslamabad44000Pakistan School of Computer Science and Engineering Yeungnam UniversityGyeongsan38428Republic of Korea

In recent advancements within wireless sensor networks(WSN),the deployment of unmanned aerial vehicles(UAVs)has emerged as a groundbreaking strategy for enhancing routing efficiency and overall network *** research introduces a sophisticated framework,driven by computational intelligence,that merges clustering techniques with UAV mobility to refine routing strategies in *** proposed approach divides the sensor field into distinct sectors and implements a novel weighting system for the selection of cluster heads(CHs).This system is primarily aimed at reducing energy consumption through meticulously planned routing and path *** a greedy algorithm for inter-cluster dialogue,our framework orchestrates CHs into an efficient communication *** comparative analysis,the proposed model demonstrates a marked improvement over traditional methods such as the cluster chain mobile agent routing(CCMAR)and the energy-efficient cluster-based dynamic algorithms(ECCRA).Specifically,it showcases an impressive 15%increase in energy conservation and a 20%reduction in data transmission time,highlighting its advanced ***,this paper investigates the impact of various network parameters on the efficiency and robustness of the WSN,emphasizing the vital role of sophisticated computational strategies in optimizing network operations.

关键词： UAV trajectory clustering next-generation wireless sensor network(NGWSN) energy efficiency mobile sink

A numerical simulation case study of the coastal currents and upwelling in the western Persian Gulf

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Journal of Ocean Engineering and Science 2020年第4期5卷 323-332页

作者： Hesameddin Mehrfar Masoud Torabi Azad kamran Lari abbas-Ali Ali-Akbari Bidokhti Department of Natural Resources and Environment Islamic Azad UniversityScience and Research BranchTehranIran Department of Marine Science and Technology Islamic Azad UniversityNorth Tehran BranchTehranIran Institute of Geophysics University of TehranTehranIran

The present study employed COHERENS model as a three-dimensional hydrodynamic model to address the coastal currents in the western Persian Gulf with a horizontal resolution of 2-minutes of latitude and *** obtained results suggested that Iranian northwestward coastal currents developed from January to April and experienced their maximum intensity from June to August when the rate of the surface inflow current increases through the Strait of Hormuz and the stability of the seasonal thermocline becomes gradually *** simulation results reflected that expansions of the thermocline area began by the arrival of the warm *** such circumstances,some stronger coastal currents were generated in *** strong coastal surface current in the vicinity of the western part of Iranian coasts flew southeastward,while the reverse current flew with a northwestern direction in the *** obtained results suggested that a consequence of the influence of salinity flux,especially on the Iranian coasts,the speed of currents *** findings of this study showed that more kinetic energy was accumulated along Iranian ***,the current vectors on Iranian coasts were greater than those on Arabian coasts,which in turn resulted in the creation of the upwelling currents along western Iranian coasts.

关键词： Coastal Currents COHERENS Model Numerical Simulation Persian Gulf(PG) Upwelling

Design and Optimization of 3D Radial Slot Grain Configuration

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Chinese Journal of Aeronautics 2010年第4期23卷 409-414页

作者： Ali kamran School of Astronautics Beijing University of Aeronautics and Astronautics

Upper stage solid rocket motors （SRMS） for launch vehicles require a highly efficient propulsion system. Grain design proves to be vital in terms of minimizing inert mass by adopting a high volumetric efficiency with minimum possible sliver. In this arti- cle, a methodology has been presented for designing three-dimensional （3D） grain configuration of radial slot for upper stage solid rocket motors. The design process involves parametric modeling of the geometry in computer aided design （CAD） software through dynamic variables that define the complex configuration. Grain bum back is achieved by making new surfaces at each web increment and calculating geometrical properties at each step. Geometrical calculations are based on volume and change-in-volume calculations. Equilibrium pressure method is used to calculate the internal ballistics. Genetic algorithm （GA） has been used as the optimizer because of its robustness and efficient capacity to explore the design space for global optimum solution and eliminate the requirement of an initial guess. Average thrust maximization under design constraints is the objective function.

关键词： solid rocket motors 3D grains radial slot configuration internal ballistics computer aided design heuristic optimization genetic algorithm

Electro-optomechanical switch via tunable bistability and four-wave mixing

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Chinese Physics B 2019年第11期28卷 193-203页

作者： kamran Ullah Department of Physics Quaid-i-Azam University

We investigate the tunable bistable behavior of a hybrid nano-electro-optomechanical system(NEOMS) composed of S-shaped in the presence of two-level atoms, trapped inside a Fabry–Pérot cavity, and driven by a strong driving field and a weak probe field. The bistable behavior of the steady-state photon number and the mechanical steady-state positions are discussed. Further, we tune bistability by tuning all the coupling frequencies involved in the system and amplitude of the driving field. The present study provides the possibility of realization of a controllable optical switch depending on atom-field coupling, optomechanical coupling, electrostatic Coulomb coupling, and threshold power. In addition, we discuss that the non-linear effect of the hybrid NEOMS generates the four-wave mixing(FWM) process. Moreover, we show that the FWM process can be suppressed by the atom-field detuning and cavity-field detuning, which exhibits low photon transmission.

关键词： nano-electro-optomechanics nano-resonators two-level atom optical switch optical bistability four-wave mixing

Estimation of the water productivity of different varieties of wheat and rice in the context of agronomic, physiological and nutritional attributes

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International Journal of Agricultural and Biological Engineering 2024年第5期17卷 200-205页

作者： Moneeza abbas Sadia Nawaz Ammara Fatima Muhammad kamran Fakhra Aslam Saima Atif Fatima Younas Department of Environmental Science Lahore College for Women UniversityLahore 54000Pakistan Institute of Biochemistry and Biotechnology University of Vetrinary&Animal SciencesLahore 54000Pakistan Department of Agronomy Faculty of AgricultureUniversity of SargodhaSargodha 40100Pakistan

Water shortage is a global concern, and it poses a particularly severe threat in Pakistan. It is estimated that over 60% of irrigation water is not efficiently applied or not efficiently utilized by crop depending upon genetic variability. The pot study was conducted to evaluate the water efficiency of various wheat varieties (Millat 2011, Galaxy 2013, Faisalabad 2008, and Gandum-1) and rice varieties (Punjab Basmati, Chenab Basmati, B-515, and PS-2) based on their photosynthetic efficiency and nutritional quality by measuring their protein and chlorophyll contents. The highest concentrations of protein and chlorophyll were observed in plants of both crops that were watered and cultivated with 50 mL of water. For wheat, the greatest leaf length (cm), net assimilation rate [g/(d∙m2)], and photosynthetic efficiency were achieved when 80 mL of water was applied. Similarly, rice varieties (Punjab Basmati, Chenab Basmati, B-515, and PS-2) exhibited the highest photosynthetic efficiency, leaf length, net assimilation rate, and chlorophyll content when grown with 80 mL of water. Therefore, a conservative cultivation of wheat and rice is possible by selecting efficient varieties and by improving the technological approach of water saving through irrigation level and wise scheduling. The judicious use of water not only limits losses but also improves productivity, particularly in scenarios of water scarcity.

关键词： water productiviy wheat rice agronomy physiology nutrition

The impact of climatic variables on the population dynamics of the main malaria vector, Anopheles stephensi Liston(Diptera: Culicidae), in southern Iran

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Asian Pacific Journal of Tropical Medicine 2020年第10期13卷 448-455页

作者： Madineh abbasi abbas Rahimi Foroushani Tohid Jafari-Koshki kamran Pakdad Hassan Vatandoost Ahmad Ali Hanafi-Bojd Deparment of Medical Entomology&Vector Control School of Public HealthTehran University of Medical SciencesTehranIran Infectious and Tropical Diseases Research Center Tabriz University of Medical SciencesTabrizIran Department of Epidemiology and Biostatistics School of Public HealthTehran University of Medical SciencesTehranIran Molecular Medicine Research Center Tabriz University of Medical SciencesTabrizIran Department of Statistics and Epidemiology Faculty of HealthTabriz University of Medical SciencesTabrizIran Department of Parasitology&Mycology Paramedical SchoolShahid Beheshti University of Medical SciencesTehranIran

Objective:To determine the significance of temperature,rainfall and humidity in the seasonal abundance of Anopheles stephensi in southern ***:Data on the monthly abundance of Anopheles stephensi larvae and adults were gathered from earlier studies conducted between 2002 and 2019 in malaria prone areas of southeastern *** data for the studied counties were obtained from climatology *** estimating equations method was used for cluster correlation of data for each study site in different ***:A significant relationship was found between monthly density of adult and larvae of Anopheles stephensi and precipitation,max temperature and mean temperature,both with simple and multiple generalized estimating equations analysis(P<0.05).But when analysis was done with one month lag,only relationship between monthly density of adults and larvae of Anopheles stephensi and max temperature was significant(P<0.05).Conclusions:This study provides a basis for developing multivariate time series models,which can be used to develop improved appropriate epidemic prediction systems for these ***-term entomological study in the studied sites by expert teams is recommended to compare the abundance of malaria vectors in the different areas and their association with climatic variables.

关键词： Anopheles stephensi Climatic variables Monthly activity Iran

An improved porous media model for nuclear reactor analysis

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Nuclear Science and Techniques 2016年第1期27卷 117-140页

作者： Roozbeh Vadi kamran Sepanloo Schools of Nuclear Safety Research and Radiation Protection Nuclear Science and Technology Research InstituteEnd of North Karegar Ave.P.O.Box:14359-836TehranIran

In this study, two modifications are proposed to mitigate drawbacks of the conventional approach of using the ‘‘Porous Media Model''(PMM) for nuclear reactor analysis. In the conventional approach, whole reactor core simplifies to a single porous medium and also, the resistance coefficients that are essential to using this model are constant values. These conditions impose significant errors and restrict the applications of the model for many cases,including accident analysis. In this article, the procedures for calculating the coefficients are modified by introducing a practical algorithm. Using this algorithm will result in obtaining each coefficient as a function of mass flow ***, the method of applying these coefficients to the reactor core is modified by dividing the core into several porous media instead of one. In this method, each porous medium comprises a single fuel assembly. PMM with these two modifications is termed ‘‘multi-region PMM'' in this study. Then, the multi-region PMM is introduced to a new CFD-based thermo-hydraulic code that is specifically devised for combining with neutronic *** CITVAP code, which solves multi-group diffusion equations, is the selected as the neutronic part for this study. The resulting coupled code is used for simulation of natural circulation in a MTR. A new semi-analytic method,based on steady-state CFD analysis is developed to verify the results of this case. Results demonstrate considerable improvement, compared to the conventional approach.

关键词：多孔介质模型模型分析反应器传统方法应用程序流体力学分析稳态计算 PMM

Microstructural Evolution of NiTi47.7Cu6.3 Alloy during Hot Deformation

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Journal of Materials Science & Technology 2011年第10期27卷 951-960页

作者： Amir Etaati kamran Dehghani Mining and Metallurgical Eng.Dept. Amirkabir Univ.Tech.

In the present work, the hot workability and microstructural evolution of ***6.3 （at.%） shape memory alloy were investigated by using wedge-rolling test. The wedge specimens were subjected to hot rolling at the temperatures of 700-1000℃. The microstructural evolutions at the strains of 0.05, 0.15, 0.2, 0.25 and 0.3 were then characterized by optical microscopy and scanning electron microscopy （SEM） as well as energy dispersive spectrometry （EDS） technique. Depending on the deformation temperature and strain, the dynamic recrystallization （DRX） could occur, leading to the refining of the microstructure. At low temperatures of 700 and 800℃ there was no sign of DRX at all studied strains. At these temperatures, the formed fine needle-like precipitates pinned the grain boundaries and prevented them from bulging/migration. By contrast, at higher temperatures of 900 and 1000℃, the DRX took place at the critical strains lower than 0.25 and 0.15, respectively. However, at higher temperatures, strain-induced-boundary-migration （SIBM） mechanism resulted in the formation of DRX grains.

关键词： Deformation Wedge rolling test Dynamic recrystallization Ni-rich Nitinol NiTiCu