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دسترسی آزاد مقاله
1 - Effects of mixed electric field on characterization of electrohydrodynamics drying system
Hamid Ghomi Pourya Seyfi Ahmad Khademi Amir HeidariIn this paper, we present a new structure of applying two electrical power supplies to generate ionic wind.In this configuration, two power supplies were applied simultaneously with a modulated voltage to anelectrohydrodynamic (EHD) system then corona discharge paramete چکیده کاملIn this paper, we present a new structure of applying two electrical power supplies to generate ionic wind.In this configuration, two power supplies were applied simultaneously with a modulated voltage to anelectrohydrodynamic (EHD) system then corona discharge parameters and EHD thrust characterizationwas investigated by a corona dryer mechanism. The EHD thrust experiments were performed with a pinto plate and SDBD arrangements. The results show that with the simultaneous application of two powersupplies the drying rate in a drop of water as a standard sample was greatly enhanced and the drying time was reduced. Thus, the total evaporation was occurred in 1 minute in the SDBD structure with a power of 7 watts and in 1.5 minutes in pin to plate structure with a power of 2.5 watts. Eventually, it was observed that the use of mixed electric fields enhances the ionic wind, hence increases the non-thermal evaporation process significantly. Furthermore, the drying rate has grown notably In SDBD configuration. پرونده مقاله -
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2 - Dielectric, electro-optical and spectroscopic properties of silver doped zinc oxide-ferroelectric liquid crystal composite system
Kaushlendra Agrahari Sanjeev Trivedi Ram Awasthi Vivek Nautiyal Rakesh Sonker Rajiv ManoharIn the present study, silver doped zinc oxide nanoparticles (NPs) have been added in the pristine ferroelectric liquid crystal (FLC). The dielectric, electro-optical and spectroscopic properties was investigated of the pristine FLC and FLC-NPs composite system. The disp چکیده کاملIn the present study, silver doped zinc oxide nanoparticles (NPs) have been added in the pristine ferroelectric liquid crystal (FLC). The dielectric, electro-optical and spectroscopic properties was investigated of the pristine FLC and FLC-NPs composite system. The dispersion of NPs into the pristine FLC material sturdily influences the various properties of composite system. Due to dispersion of NPs, a rapid increment in the dielectric permittivity and faster switching was observed for the FLC-NPs composite system. Absorbance of the UV light got diminished in the presence of silver doped zinc oxide NPs. Photoluminescence emission of the pristine FLC material has been quenched after the addition of NPs and a red shift was also detected. The possible applications of this investigation have been suggested in the letter. پرونده مقاله -
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3 - Relativistic dynamics of electrons around impurities in high-density plasmas
Said Douis Mohammed Tayeb MeftahAbstractIn this work, we focus our attention on the dynamic properties of relativistic electrons moving around an impurity in a plasma. This led us, in the first place, to compute the effective plasma potential (EPP) in which the electrons move. The EPP is built up as a چکیده کاملAbstractIn this work, we focus our attention on the dynamic properties of relativistic electrons moving around an impurity in a plasma. This led us, in the first place, to compute the effective plasma potential (EPP) in which the electrons move. The EPP is built up as a sum of three contributions. These include the potential created by the impurity, the potential due to the ions assumed to form a uniform background of positive electric charges and the potential due to all the electrons. It turns out that the last potential depends on an integral of a function of the EPP in question. This then leads to a nonlinear integral equation where the EPP is the main quantity to compute. Thanks to the EPP, we derive the electron trajectories and compute their total electric field (microfield) at the impurity. According to different plasma conditions, two dynamical properties are then calculated: the time auto-correlation function of this microfield and the dielectric constant. These properties are calculated for both the relativistic case and non-relativistic (classical) case. The comparison between the relativistic and the classical results are also done for the different plasma conditions. پرونده مقاله -
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4 - Characterization of argon/air atmospheric pressure capacitively coupled radio frequency dielectric barrier discharge regarding parasitic capacitor at 13.56 MHz
Farshad Sohbatzadeh Saeed Mirzanejhad Hoda Mahdavi Zahra OmidiAbstractIn this paper, uniform argon glow discharge at atmospheric pressure in a diffuse mode driven by a 300-W radio-frequency (13.56 MHz) power supply based on dielectric barrier discharge was investigated. In this work, the effect of the parasitic capacitor on the el چکیده کاملAbstractIn this paper, uniform argon glow discharge at atmospheric pressure in a diffuse mode driven by a 300-W radio-frequency (13.56 MHz) power supply based on dielectric barrier discharge was investigated. In this work, the effect of the parasitic capacitor on the electrical characteristics of the capacitively coupled atmospheric pressure plasma was investigated. It was revealed that more than half of the RF current is parasitic in our system as a characteristic of the capacitively coupled plasma. It was also proved that the discharge resistance and sheath capacitance increase at higher input powers while the impedance decreases. In order to recognize plasma, optical emission spectroscopy apparatus was used. Argon, oxygen, copper, and nitrogen spectrum lines were diagnosed. The plasma gas temperature and electronic excitation temperature were investigated showing a non-equilibrium discharge. پرونده مقاله -
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5 - Temperature dependence dielectric behavior of Ge-doped lead scandium tantalate single crystals
Chandra Kumar Dixit Anil Kumar SrivastavaAbstractThe doping of Pb2SeTaO6 with Ge ferroelectrics was produced by a high-temperature solution method. We measure dielectric constant, dielectric loss and conductivity in the temperature range −30°C to 200°C and frequency range 1 to 100 KHz. The value of dielectric چکیده کاملAbstractThe doping of Pb2SeTaO6 with Ge ferroelectrics was produced by a high-temperature solution method. We measure dielectric constant, dielectric loss and conductivity in the temperature range −30°C to 200°C and frequency range 1 to 100 KHz. The value of dielectric constant of the Pb2SeTaO6 (PST) crystal remained the same after thermal annealing whereas they decreased after Ge doping in the phase transition temperature range of the PST single crystal. All samples were investigated for conductivity with increasing temperature. پرونده مقاله -
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6 - Analysis of discharge parameters and optimization study of coaxial DBDs for efficient excimer light sources
Udit Narayan Pal Pooja Gulati Niraj Kumar Mahesh Kumar Vishnu Srivastava Ram PrakashAbstractIn this work, a xenon-filled quartz coaxial dielectric barrier discharge (DBD) tube (ID 6 mm, OD 12 mm) at 400-mbar pressure has been studied at different operating conditions. High-frequency sinusoidal and unipolar pulse-like voltages are applied at the dischar چکیده کاملAbstractIn this work, a xenon-filled quartz coaxial dielectric barrier discharge (DBD) tube (ID 6 mm, OD 12 mm) at 400-mbar pressure has been studied at different operating conditions. High-frequency sinusoidal and unipolar pulse-like voltages are applied at the discharge electrodes for the generation of micro-discharge plasma. Visual images of the discharge and the electrical waveform confirm the diffused-type discharge. The mechanism that is involved in the ignition, development and extinction of DBDs is quantitatively explained by dynamic processes in the discharge. An equivalent electrical model representing the DBD phenomenon has also been used to validate the characteristic discharge parameters. The relative intensity analysis of the Xe continuum peak at wavelength 172 nm in the optical emission spectra of the vacuum ultraviolet region has been carried out for different operating conditions. Approximately three times increment in the radiation is observed in pulse excitation over sinusoidal excitation. It infers that the pulsed excitation of DBD sources is advantageous for excimer light sources. پرونده مقاله -
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7 - Diagnostic of plasma discharge parameters in helium filled dielectric barrier discharge
Pooja Gulati Udit Narayan Pal Mahesh Kumar Ram Prakash Vishnu Srivastava Vimal VyasAbstractThis paper reports the plasma discharge analysis of a dielectric barrier discharge (DBD) source. Helium is used as a working gas. The analysis is performed at fixed working pressure and operating frequency. The investigations are carried out using sinusoidal sup چکیده کاملAbstractThis paper reports the plasma discharge analysis of a dielectric barrier discharge (DBD) source. Helium is used as a working gas. The analysis is performed at fixed working pressure and operating frequency. The investigations are carried out using sinusoidal supply for the generation of discharges where two current pulses have been observed with different polarities in one period. A homogeneous type of discharge has been observed for different operating conditions in this DBD source. Since in situ diagnostics are not possible due to the small geometries in the used DBD source, the electrical measurements and spectroscopic analysis of the discharge have been performed to analyse the plasma discharge. The electrical analysis has been carried out using equivalent electrical circuit model. The plasma density and temperature within the discharge have been estimated using line ratio technique of the observed visible neutral helium lines. The estimated electron plasma density is found to be in close proximity with the plasma simulation code ‘OOPIC Pro’. پرونده مقاله -
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8 - Investigation of the effects of pulse repetition frequency in a mixed electric field on a SDBD-like plasma jet
Amir Abbas Heidari Pourya Seyfi Ahmad Khademi Hamid GhomiIn this paper, the design, performance and characterization of a low temperature argon plasma jet with a SDBD-like structure are presented. Based on this structure, the argon plasma jet is generated in a SDBD-like structure with a mixed electric field. SDBD-like structu چکیده کاملIn this paper, the design, performance and characterization of a low temperature argon plasma jet with a SDBD-like structure are presented. Based on this structure, the argon plasma jet is generated in a SDBD-like structure with a mixed electric field. SDBD-like structure, refers to the plasma jet generated by the surface dielectric barrier discharge. The effects of high frequency electric pulse as the main igniter for plasma jet generation and low frequency sinusoidal electric field in order to modify the dynamic behavior of plasma jet are investigated in this paper. The effect of these variations on the plasma jet along with the decrease in pulse repetition frequency were recorded by Schlieren imaging method. This study revealed the important role of decreasing the pulse repetition frequency in the mixed electric field in the SDBD-like plasma jet structure. Increasing the cross-sectional area of the plasma colliding with the target surface is the most important advantage of this structure for the generation of plasma jets. Also, the trend of decreasing plasma column continuity with increasing pulse repetition frequency is another result of this study. Under these conditions, the diameter of the cross section of the plasma jet increases to 9 mm without increasing the consumption of more electrical power and with equal jet length. Finally, the surface hydrophilicity was measured after treatment by plasma jet and the operation resulted in a super-hydrophilic surface. پرونده مقاله -
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9 - Measurement of dielectric loss tangent at cryogenic temperature using superconducting film resonator
Yufang Zhang Zhenqing WangAbstractWe demonstrate that the superconducting film resonator can be used to accurately and quantitatively measure the microwave dielectric loss tangent of a variety of materials. Compared to traditional dielectric resonator loaded metal cavity method, it has advantage چکیده کاملAbstractWe demonstrate that the superconducting film resonator can be used to accurately and quantitatively measure the microwave dielectric loss tangent of a variety of materials. Compared to traditional dielectric resonator loaded metal cavity method, it has advantage of small sample size (~2–3 orders of magnitude smaller than the old method), and much higher sensitivity to measure small loss tangent values as small as 10−5 at around 7 GHz band at cryogenic temperatures. This method can be utilized widely in study of mechanism of microwave loss at cryogenic temperature range, which is extremely important in superconducting microwave application areas, such as novel super quantum computers. پرونده مقاله -
دسترسی آزاد مقاله
10 - Time-dependent one-dimensional simulation of atmospheric dielectric barrier discharge in N2/O2/H2O using COMSOL Multiphysics
F. Sohbatzadeh H. SoltaniAbstractThe results of time-dependent one-dimensional modelling of a dielectric barrier discharge (DBD) in a nitrogen–oxygen–water vapor mixture at atmospheric pressure are presented. The voltage–current characteristics curves and the production of active species are st چکیده کاملAbstractThe results of time-dependent one-dimensional modelling of a dielectric barrier discharge (DBD) in a nitrogen–oxygen–water vapor mixture at atmospheric pressure are presented. The voltage–current characteristics curves and the production of active species are studied. The discharge is driven by a sinusoidal alternating high voltage–power supply at 30 kV with frequency of 27 kHz. The electrodes and the dielectric are assumed to be copper and quartz, respectively. The current discharge consists of an electrical breakdown that occurs in each half-period. A detailed description of the electron attachment and detachment processes, surface charge accumulation, charged species recombination, conversion of negative and positive ions, ion production and losses, excitations and dissociations of molecules are taken into account. Time-dependent one-dimensional electron density, electric field, electric potential, electron temperature, densities of reactive oxygen species (ROS) and reactive nitrogen species (RNS) such as: O, O−, O+, O2-documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ { ext{O}}_{2}^{ - } $$end{document}, O2+documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ { ext{O}}_{2}^{ + } $$end{document}, O3, N,N2+documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ { ext{N}}, { ext{N}}_{2}^{ + } $$end{document}, N2s and N2-documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ { ext{N}}_{2}^{ - } $$end{document} are simulated versus time across the gas gap. The results of this work could be used in plasma-based pollutant degradation devices. پرونده مقاله -
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11 - Quantum analytical modeling and simulation of CNT on insulator (COI) and CNT on nothing (CON) FET: a comparative analysis
Sudipta Mukherjee Dipan Bandyopadhyay Pranab Kishore Dutta Subir Kumar SarkarAbstractA comprehensive performance analysis by quantum analytical modeling of CNT on insulator (COI) and CNT on nothing (CON) FET having channel length 20 nm has been proposed and investigated on the basis of 2D Poisson’s Equation and solution of 1-D Schrodinger’s Equa چکیده کاملAbstractA comprehensive performance analysis by quantum analytical modeling of CNT on insulator (COI) and CNT on nothing (CON) FET having channel length 20 nm has been proposed and investigated on the basis of 2D Poisson’s Equation and solution of 1-D Schrodinger’s Equation and validated using ATLAS 2D simulator. As classical approximations fail to describe carrier quantization, charge inversion and potential profile of a device at sub-100 nm regime, here for the first time an analytical model in quantum mechanical aspect for COI/CON devices has been derived. Effects of high-k dielectrics in place of conventional SiO2 over the device characteristics have been thoroughly discussed. Moreover, all noticeable benefits of our device to the so called SOI/SON architecture have also been vividly justified. پرونده مقاله -
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12 - Inactivation of Aspergillus flavus spores in a sealed package by cold plasma streamers
F. Sohbatzadeh S. Mirzanejhad H. Shokri M. NikpourAbstractThe main objective of this study is to investigate the inactivation efficacy of cold streamers in a sealed package on pathogenic fungi Aspergillus flavus (A. flavus) spores that artificially contaminated pistachio surface. To produce penetrating cold streamers, چکیده کاملAbstractThe main objective of this study is to investigate the inactivation efficacy of cold streamers in a sealed package on pathogenic fungi Aspergillus flavus (A. flavus) spores that artificially contaminated pistachio surface. To produce penetrating cold streamers, electric power supply was adapted to deposit adequate power into the package. The plasma streamers were generated by an alternating high voltage with carrier frequency of 12.5 kHz which was suppressed by a modulated pulsed signal at frequency of 110 Hz. The plasma exposition time was varied from 8 to 18 min to show the effect of the plasma treatment on fungal clearance while the electrode and sample remained at room temperature. This proved a positive effect of the cold streamers treatment on fungal clearance. Benefits of deactivation of fungal spores by streamers inside the package include no heating, short treatment time and adaptability to existing processes. Given its ability to ensure the safety and longevity of food products, this technology has great potential for utilization in food packaging and processing industry. In this study, moisture and pH changes of pistachio samples after plasma streamers treatment were also investigated. پرونده مقاله -
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13 - Estimation of photo-degradation of dielectrics surrounding the narrow channel due to PD activity
Alireza A. GanjoviAbstractPartial discharge (PD) taking place within narrow channels produces a large number of charged particles, causing degradation of the polymer. Additionally, PD pulses also produce UV photons due to decay of excited states (radiative states) in air. These may have چکیده کاملAbstractPartial discharge (PD) taking place within narrow channels produces a large number of charged particles, causing degradation of the polymer. Additionally, PD pulses also produce UV photons due to decay of excited states (radiative states) in air. These may have enough energy to break C–C bonds and thereby add to the degradation of the dielectrics surrounding the narrow channel. In this paper, a radiation transport (RT) model has been developed and integrated with a Particle-in-Cell/Monte Carlo collision (PIC-MCC) model to study the behavior of excited (radiative) states of air within discharge in the narrow channel. The radiative state atoms are described by a fluid model combined with the Holstein–Biberman equation. This model has the ablation to follow the spatial evolution of the radiative excited-state density throughout narrow channel. The effect of applied electric field, narrow channel dimensions, gas pressure on the extent of degradation of dielectrics surrounding the narrow channel is studied. پرونده مقاله -
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14 - Start current and growth rate in Smith–Purcell free-electron laser with dielectric-loaded cylindrical grating
Zahra Rezaei Bizhan FarokhiAbstractWe present an analytic theory for Smith–Purcell device in which a cylindrical metal–dielectric grating was derived by an annular electron beam propagating along the grating axis. A dispersion relation is obtained for azimuthally symmetric modes. Also, the first- چکیده کاملAbstractWe present an analytic theory for Smith–Purcell device in which a cylindrical metal–dielectric grating was derived by an annular electron beam propagating along the grating axis. A dispersion relation is obtained for azimuthally symmetric modes. Also, the first-order and second-order growth rates of the modes which are in phase with the beam are compared. It is shown that the second-order growth rate gives a more accurate description of beam–wave interaction for beams with larger thicknesses, as well as grating slots, with smaller depths and greater lengths. The start current for BWO operation of the SP-FEL is presented too. The importance of the minimum value of start current is that above it, the SP-FEL will operate as an oscillator, even in the absence of external feedback. In this case, the group velocity of the synchronous evanescent wave is negative, while the electron beam travels in the forward direction. It is shown in this paper that the dielectric and grating parameters affect the value of start current. So, by changing these parameters, the minimum value for the start current can be obtained. پرونده مقاله -
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15 - The effects of applying different bias voltages and phase differences on performance of an asymmetric surface dielectric barrier discharge; an experimental investigation
H. Mahdavi F. SohbatzadehAbstractIn the present research, the performance of the electrohydrodynamic force in an asymmetric surface dielectric barrier discharge actuator has been investigated at different bias voltages. The effects of DC, AC plus DC (DC-offset), and sinusoidal bias voltages on چکیده کاملAbstractIn the present research, the performance of the electrohydrodynamic force in an asymmetric surface dielectric barrier discharge actuator has been investigated at different bias voltages. The effects of DC, AC plus DC (DC-offset), and sinusoidal bias voltages on the force generation have been studied through measuring the electric wind velocity profiles, surface potential, and electric field. The results showed that applying DC and DC-offset biases to the lower electrode instead of connecting it to the ground in a typical case increased the charge deposition on the dielectric surface and consequently reduced the electrohydrodynamic force generation. This effect was also observed in case of exchanging these voltages with AC sinusoidal voltage of the upper electrode. In addition, as a new idea, two-phase shifted AC voltage was applied to the electrodes and the resulting changes have been studied. The obtained results at 180∘documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$180^{^circ }$$end{document} phase difference were very noticeable and showed 46% improvement in the maximum velocity of the induced flow relative to the grounded electrode with the same input power. Using this technique, a certain wind velocity can be obtained at relatively lower voltages and input powers compared to the conventional case of grounding the lower electrode. Such a capability is significant in aerodynamic applications, where applying large values of the high voltages may disturb the operational systems. پرونده مقاله -
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16 - Thermal and electro-optic properties of graphene oxide-doped hexylcyanobiphenyl liquid crystal
Şükrü Özgan Hasan Eskalen Yusuf TapkıranlıAbstractHexylcyanobiphenyl liquid crystal was doped with graphene oxide at ratios %0.25GO, %0.5GO, %1GO and %2GO, and the change in physical properties of pristine and the doped liquid crystals has been investigated. The phase transitions of prepared samples were studie چکیده کاملAbstractHexylcyanobiphenyl liquid crystal was doped with graphene oxide at ratios %0.25GO, %0.5GO, %1GO and %2GO, and the change in physical properties of pristine and the doped liquid crystals has been investigated. The phase transitions of prepared samples were studied by differential scanning calorimeter and polarized optical microscopy. The differential scanning calorimeter and polarized optical microscopy results are in good agreement when examining the nematic–isotropic liquid phase transition temperatures of the hexylcyanobiphenyl. The liquid crystal texture images obtained with polarized optical microscopy reveals that thermal stability of sample changed with graphene oxide concentration, i.e., increased with graphene oxide concentration. Impedance, capacitance, conductivity and real and imaginary dielectric constants of the pure and doped liquid crystals were obtained depending on frequency and voltage at the room temperature by using impedance analyzer. These electrical properties of the pure and the graphene oxide-doped samples showed an increase with increasing the graphene oxide ratio. The voltage-dependent light transmittance experiment revealed that threshold voltage of LC cells decreased for %0.25GO- and % 1GO-dispersed samples, but it was increased at %0.5GO- and %2GO-dispersed samples. پرونده مقاله -
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17 - Effect of ion trapping behavior of TiO2 nanoparticles on different parameters of weakly polar nematic liquid crystal
Geeta Yadav Rohit Katiyar Govind Pathak Rajiv ManoharAbstractIn the present investigation, TiO2-doped weakly polar nematic liquid crystal (NLC) has been studied. This study mainly focuses on dielectric, electro-optical and optical properties of pure NLC and doped systems. Variation in different parameters like dielectric چکیده کاملAbstractIn the present investigation, TiO2-doped weakly polar nematic liquid crystal (NLC) has been studied. This study mainly focuses on dielectric, electro-optical and optical properties of pure NLC and doped systems. Variation in different parameters like dielectric permittivity, dielectric loss, dielectric anisotropy and conductivity has been noticed. Permittivity of the doped system is almost the same as undoped system. With doping concentration, the ionic contribution to the dielectric loss as observed in low-frequency region has been suppressed and the shift in relaxation frequency toward higher frequency side has also been observed. The electrical conductivity and threshold voltage have been decreased with increasing concentration of nanoparticles (NPs). The continuous increase in dielectric anisotropy with increasing the concentration of NPs has also been observed. These results have been attributed to the trapping capability of free ions by TiO2 NPs. Further, we focused on the study of photoluminescence (PL), UV absorbance and Fourier transformed infrared spectroscopy (FTIR) of pure and doped systems. The continuous increase in PL intensity without any shift in emission peak has been observed for doped systems. Enhancement in UV absorbance with increasing concentration of NPs has also been observed. The effect of NPs doping on molecular dynamics of NLC can be clearly seen by FTIR study. The results suggest that the TiO2 NP-doped weakly polar NLC can have significant improved dielectric, electro-optical and optical properties. This makes the weakly polar NLC to be a potential candidate for many applications. پرونده مقاله -
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18 - Silver nanoparticles dispersed in nematic liquid crystal: an impact on dielectric and electro-optical parameters
Rohit Katiyar Kaushlendra Agrahari Govind Pathak Tripti Vimal Geeta Yadav Kamal Kumar Pandey Abhishek Kumar Misra Atul Srivastava Rajiv ManoharAbstractIn the present study, nematic liquid crystal (NLC) 4′-(Octyloxy)-4-biphenylcarbonitrile dispersed with three different concentrations of silver nanoparticles (Ag NPs) is characterized by electro-optical and dielectric spectroscopy method. The dispersion of Ag NP چکیده کاملAbstractIn the present study, nematic liquid crystal (NLC) 4′-(Octyloxy)-4-biphenylcarbonitrile dispersed with three different concentrations of silver nanoparticles (Ag NPs) is characterized by electro-optical and dielectric spectroscopy method. The dispersion of Ag NPs into NLC material leads to the change in physical parameters such as dielectric permittivity, photoluminescence, threshold voltage, response time and splay elastic constant. The AC conductivity and threshold voltage of Ag NPs-dispersed composite system have increased significantly. The increase in the AC conductivity for the composite system is attributed to the Ag NPs-assisted induced charge transfer mechanism in the system. Moreover, the increase in AC conductivity value for Ag NPs/NLC composite system discloses its importance in photovoltaic solar cell. پرونده مقاله -
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19 - Study of an argon dielectric barrier discharge reactor with atmospheric pressure for material treatment
Maryam Hosseinpour Akbar ZendehnamAbstractIn this study, effects of the variation in the dielectric barrier discharge’s (DBD) gap distance and the nature of dielectric layers which cover both of the reactor electrodes on the electron density, mass fraction of excited argon atoms across the discharge gap چکیده کاملAbstractIn this study, effects of the variation in the dielectric barrier discharge’s (DBD) gap distance and the nature of dielectric layers which cover both of the reactor electrodes on the electron density, mass fraction of excited argon atoms across the discharge gap, mean electron energy, ion and electron current density, and electron temperature are investigated at atmospheric pressure. In order to find the optimal reactor gap, the DBD’s average power consumption is studied. The achievements show that when the value of dielectric constant is increased from 7.6 to 10, discharge gap of 1 mm still demonstrates the maximum power consumption, which can be considered as the optimum discharge gap. To optimize the characteristics of one-dimensional modeling of DBD system for material treatment, various types of materials with different values of the permittivity [aluminum, glass (quartz) and silicon] are embedded in the discharge gap between the two electrodes. In this case, the reactor gap is changed from 0.5 mm to 2 mm, while the dielectric constant of the dielectric layers which cover both of the metallic electrodes is assumed to be 10. Compared to the other examined materials, our numerical results illustrate that the treated material with higher value of the relative permittivity (silicon) has greater influences on the variations in the electron density, argon ion density and also total plasma current density than in the values of excited argon atom density, mass fraction of excited argon atoms and also average power consumption. پرونده مقاله -
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20 - Comparative study of behavior of electrical conductivity in KI‒Al2O3 and KI‒TiO2 heterostructure composites
Suhail Iqbal Wani Nazli Zeeshan RafiuddinAbstractThe present work reports development of binary KI–Al2O3 and KI–TiO2-based nanocomposites using simple solid-state reaction method and is characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and impedance spect چکیده کاملAbstractThe present work reports development of binary KI–Al2O3 and KI–TiO2-based nanocomposites using simple solid-state reaction method and is characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and impedance spectroscopy. The results show the effect of heterogeneously doped Al2O3 and TiO2 on the ionic conductivity of pure KI which is moderately conductive. The results supported the composite development in which the interface layer portrays a significant part in governing the bulk properties of the compound. Improvement in electrical conductivity is seen in the incorporation of Al2O3 and TiO2 dispersoid into the matrix of KI. With temperature, electrical conductivity increased and the activation energies were found to be decreasing. The activation energies for KI–Al2O3 and KI–TiO2 systems were 0.22 eV and 0.21 eV, respectively, in the temperature range 20‒400 °C. Dielectric constant increases with the increase in temperature in the entire temperature range studied attributed to the phenomenon of distortion of electric charges. پرونده مقاله -
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21 - Theoretical Investigation of Solvent Effects on The Structural Changes of I - Pentadeeanoyl - 2 - Docosahexaenoyl - Sn - Glycerol -3 -Phosphoeholin
N. Khodayari B. Honarparvar M. Monajjemi K. ParivarTheoretically predictionq of the solvent effects of I - pentadecanoyl - 2 -docosahexaennyl - Sn - glycerol3 - phosphocholin have been studied using 'Jamey-lock quantiun chemical approximation and STD - 30basis set within the Onsager Self-Consistent Reaction field (SCRS' چکیده کاملTheoretically predictionq of the solvent effects of I - pentadecanoyl - 2 -docosahexaennyl - Sn - glycerol3 - phosphocholin have been studied using 'Jamey-lock quantiun chemical approximation and STD - 30basis set within the Onsager Self-Consistent Reaction field (SCRS') model All optimized conformers of I -pentadecanoyl - 2 -docosahexaenoyI - Sn - glycerol 3 - phosphocholin as well as their total relativeenergies in terms of the most stable conformer in as phase and different solvent media such as water.ethanol. methanol and IMISO have been calculated. According to the obtained resulLz the I - pentadecanoyl- 2 - docosahexaeneyl - Sn - glycerol - 3 - phosphocholin configuration has the most neeative energyvalues and then has been found to be the most stable conformer. In this aspect the gaph of relative energyvalues versus dielectric. constants (c) as well as Ln (I /c) of employed solvents has been plotted and theobserved trend has been analyzed.For further investigation, the effect of solvent's polarity on the dipole moments of 1-pentadecanoyl - 2 -docosahexaenoyl - Sn - glycerol - 3 - phosphocholin in various solvent media have been reported andcompared with the gas phase. We would like to note that the dipole moment variations revealed that thevalues or the computed dipole moment seems to he solvent - dependent because this property is closelyrelated to the en viromnental effects the greatest dipole moment brings more stability which is underinfluence of solvation پرونده مقاله -
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22 - Thermodynamics of the solubility of potassium nitrate in the mixed solvent, Ethanol+Water, and the related Ion-association
M. Aghaie F. Ghaemi Amiri M. GiahiUsing the evaporating method, the solubility of potassium Nitrate was determined in various mixtures containing Water and Ethanol at 25°C. The results show that the solubility of KNo3 decreases with increasing the mass percent of Ethanol in the mixtures. This trend چکیده کاملUsing the evaporating method, the solubility of potassium Nitrate was determined in various mixtures containing Water and Ethanol at 25°C. The results show that the solubility of KNo3 decreases with increasing the mass percent of Ethanol in the mixtures. This trend is along with decreasing the dielectric constant of Water+Ethanol mixtures. Moreover, it can be concluded that the totqal solubility of KNO3 may be regarded as the sum of two contributions; one referring to the free ions in the solution and the other to K+NO3-ion-pairs which are formed in the saturated solution. Estimating the formation constant, KAm for the reaction K+(soln) + NO3-(soln) AK+NO3- (ion-pair) , upon Bjerrum or fuoss models, then it is quite easy to evaluate the contributions of free ions and K+NO3-(ion-pair) to the total solubility. پرونده مقاله -
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23 - The effect of dielectric constant and ionic strength on the solubility of lithium carbonate at 25.0 °C in thermodynamic view
M. Aghaie S. Ghafoorian B. Sh. Broojeni H. AghaieUsing the Solvent Evaporating and Atomic Emission Spectrophotometric methods, the solubilitiesof Li2CO3 were determined in various mixed- solvent "water + ethanol" with various mass percentof ethanol, and in the presence of NaNO3 in various molarities at 25.0°C . Th چکیده کاملUsing the Solvent Evaporating and Atomic Emission Spectrophotometric methods, the solubilitiesof Li2CO3 were determined in various mixed- solvent "water + ethanol" with various mass percentof ethanol, and in the presence of NaNO3 in various molarities at 25.0°C . The results wereinterpreted in terms of mean ionic activity coefficient and ion association phenomenon. پرونده مقاله -
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24 - The investigation of ionic association in the CdF2 solution with the mixed solvent (water +ethanol +propanol) at 25°C
M. Aghaie T. JaliliUsing the mixed solvents, (water +ethanol + propanol), the solubility of CdF2 was determined byevaporating method at 25° C. The results showed that the sollbility, s, of CdF2 decreases bydecreasing the dielectric constant of the mixed solvent .Once the solubility of چکیده کاملUsing the mixed solvents, (water +ethanol + propanol), the solubility of CdF2 was determined byevaporating method at 25° C. The results showed that the sollbility, s, of CdF2 decreases bydecreasing the dielectric constant of the mixed solvent .Once the solubility of CdF2 was determined,the concentration solubility product, Ksp(c)=4s3, was calculated .Furthermore ,by estimating the meanactivity coefficient, f± , of CdF2 in the solution upon the extended Debye-Hückel theory, the modelsolubility Product constant of the salt, Ksp(m)=4s3 f±3 was calculated .On the other hand we concludedthe equilibrium constant of ion pair formation , KIP, on the basis of Fuoss contact ion pair model andwe obtained the value of ion pair concentration in the mixed solvents, (water 85% +ethanol l5% +propanol 10%). The value of thermodynamic solubility product constant, Ksp(th), of CdF2 in the mixedsolvent was evaluated at zero ionic strength upon the extrapolation method and the value of ion pairconcentration was calculated in the considered solution and compared by fuoss model. پرونده مقاله -
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25 - بررسی عوامل موثر در تصفیه اکسیدهای نیتروژن در یک راکتور پلاسمای سرد
رسول یاراحمدی سید باقر مرتضوی محمدرضا امید خواه حسن اصیلیان علی خوانینهدف از این تحقیق تصفیه و حذف اکسیدهای نیتروژن در راکتور پلاسما در شرایط اتمسفریک و غیر حرارتی است. این فن آوری علاوه بر قابلیت کاهش مصرف انرژی در فرایند حذف آلاینده ها، دارای انعطاف پذیری ویژه در تصفیه و تقلیل آلاینده های فرعی به طور هم زمان است. در این تحقیق به منظور چکیده کاملهدف از این تحقیق تصفیه و حذف اکسیدهای نیتروژن در راکتور پلاسما در شرایط اتمسفریک و غیر حرارتی است. این فن آوری علاوه بر قابلیت کاهش مصرف انرژی در فرایند حذف آلاینده ها، دارای انعطاف پذیری ویژه در تصفیه و تقلیل آلاینده های فرعی به طور هم زمان است. در این تحقیق به منظور تبدیل موثر اکسید های نیتروژن(NOX)، از فرایند پلاسمای نوع تخلیه با مانع دی الکتریک[1](DBD) استفاده شده است. در اثر برخورد الکترون ها با جریان هوای حاوی اکسید های نیتروژن، رادیکال ها و مولکول های فعال در یک حجم محدود وتحت کنترل (راکتور پلاسما) تولید و سپس در حضور هیدرو کربن احیا کننده عمل تبدیل و تصفیه انجام می شود. در این تحقیق از بین عوامل موثر بر تبدیل NOx در محیط پلاسما متغیرهای دما، سرعت فضایی، نسبت مولی گاز پروپان به اکسید های نیتروژن و ولتاژ مورد بررسی قرار گرفت. اهمیت تاثیر عامل دما، اختلاف ولتاژ و گاز احیا کنند به ترتیب مشخص شد. سرعت فضایی در محدودهh-123000-11500 تاثیر معنی داری بر تبدیل آلودگی NOx نشان نداد. بررسی نتایج نشان می دهد که شرایط بهینه به منظور تبدیل NO به N2 ، O2 و NO2 عبارتند از، دمای C °180، نسبت مولی برابر پروپان و اکسید های نیتروژن و ولتاژ 10 کیلو ولت که در این حالت درجه تبدیل بهینه 78/0 با انحراف معیار 12/0 حاصل شد . در حالی که شرایط بهینه برای تبدیل و تصفیه NOx دمای C ° 180 ، نسبت مولی گاز پرو پان به اکسید های نیتروژن برابر 3/0 با ولتاز 5 کیلو ولت می باشد . در این حالت درجه تبدیل بهینه برابر53/0 با انحراف معیاری معادل 15/0 به دست آمد. پرونده مقاله -
دسترسی آزاد مقاله
26 - Microstructural Investigation of BaTiO3 Plasma Sprayed Coating Deposited by Splash and Disk-Like Splats
A.H. PaksereshtIn the thermal spray process, particulate materials can be melted by plasma atmosphere due to its high local temperature from 8700 ◦C to 15,000 ◦C. Therefore, the material powders turn into droplets after being melted by injection into the hot flame. Molten droplets are چکیده کاملIn the thermal spray process, particulate materials can be melted by plasma atmosphere due to its high local temperature from 8700 ◦C to 15,000 ◦C. Therefore, the material powders turn into droplets after being melted by injection into the hot flame. Molten droplets are accelerated toward a substrate and form the splats which quickly solidify; finally, the film is formed by pile-up splats. Splat morphology and post treatment can determine the microstructure, mechanical and physical properties of the coating. In this study, BaTiO3 films were deposited onto a mirror polished stainless steel substrates kept at room temperature and 500 ◦C. At the elevated temperatures, the desorbtion of adsorbates and condensate at the substrate surface are the most important factor which change the morphology of the splats, from irregular- splash morphology to disk-like shape. Splat morphology can determine sprayed film microstructure and effect on the coating properties. The morphology of individual splats and the post treated films were studied using scanning electron microscopy. Results indicated that the porosity in the film produced at room temperature was higher than that in the film deposited on the heated substrates. Also, results show post heat treatment can improve physical and mechanical properties of the sprayed coating. پرونده مقاله -
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27 - بررسی الگوریتم آنالیز انتشار شعاع نوری با تفاضل محدود
آیت اکبری محسن کامیار نوشین ربیعی علی بکترهدف ما در این مقاله ارائه ی روشهایی برای بدست آوردن توزیع میدان در نوک فیبر دو هسته ای باریک شده می باشد. از مهمترین این روشها، روش تفاضل محدود می باشد. برای استفاده از روش تفاضل محدود، دو آنالیز پیش رو داریم یکی آنالیز انتشار شعاع نوری می باشد که هر دو از معادلات موج م چکیده کاملهدف ما در این مقاله ارائه ی روشهایی برای بدست آوردن توزیع میدان در نوک فیبر دو هسته ای باریک شده می باشد. از مهمترین این روشها، روش تفاضل محدود می باشد. برای استفاده از روش تفاضل محدود، دو آنالیز پیش رو داریم یکی آنالیز انتشار شعاع نوری می باشد که هر دو از معادلات موج ماکسول استفاده می کنند. پرونده مقاله -
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28 - بررسی آنتنهای مسطح بر روی زیرلایههای کریستال فوتونیک و دوقطبی مسطح
محبوبه بحرینیدر حالت کلی، فوتونیک کریستال ها ساختارهایی از مواد هستند که نفوذپذیری الکتریکی و مغناطیسی آن ها به طور تناوبی در یک، دو و یا سه بعد تغییر می کند. هنگامی که یک اینچنین ساختارهایی در معرض تابش یک اشعه که دارای طول موجی قابل مقایسه با دوره ی تناوب فضایی کریستال است قرار می چکیده کاملدر حالت کلی، فوتونیک کریستال ها ساختارهایی از مواد هستند که نفوذپذیری الکتریکی و مغناطیسی آن ها به طور تناوبی در یک، دو و یا سه بعد تغییر می کند. هنگامی که یک اینچنین ساختارهایی در معرض تابش یک اشعه که دارای طول موجی قابل مقایسه با دوره ی تناوب فضایی کریستال است قرار می گیرد، دو حالت رخ می دهد ، می باشددراین مقاله بررسی آنتن های مسطح بر روی زیرلایه های کریستال فوتونیک و دوقطبی مسطح بر روی زیرلایه فوتونیک کریستال پرداخته شده است. پرونده مقاله -
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29 - بررسی مدول حجمی, فشار گذار وویژگیهای اپتیکی کلسیم کربنات درفاز اورتورومبیک بااستفاده ازروش شبه پتانسیل
حمداله صالحی امین شنبدیدر این مقاله مدول حجمی,مشتق آن , تراکم پذیری , فشار گذاروخواص اپتیکی کلسیم کربنات، در فاز ارتورومبیک (واتریت) مورد بررسی قرار میگیرد. محاسبات با استفاده از روش شبهپتانسیل در چارچوب نظریۀ تابعی چگالی باتقریب های مختلف و با استفاده از نرمافزار کوانتوم اسپرسو صورت گرفته چکیده کاملدر این مقاله مدول حجمی,مشتق آن , تراکم پذیری , فشار گذاروخواص اپتیکی کلسیم کربنات، در فاز ارتورومبیک (واتریت) مورد بررسی قرار میگیرد. محاسبات با استفاده از روش شبهپتانسیل در چارچوب نظریۀ تابعی چگالی باتقریب های مختلف و با استفاده از نرمافزار کوانتوم اسپرسو صورت گرفته است. نتایج ناشی از پایداری و فشار گذار بیانگر این است که نتایج حاصل ازتقریب نسبت به دو تقریب دیگر مطابقت بیشتری با مقادیر فشار گذار تجربی دارند. ضریب شکست بهدست آمده برای فاز ارتورومبیک(واتریت) در راستا های و به ترتیب 273/1، 274/1 و 433/1 میباشند، همچنین مقدار گاف اپتیکی برای فاز ارتورومبیک در راستاهای و محاسبه شدهاند.نتایج به دست آمده با دیگر داده های موجود سازگاری خوبی دارد. پرونده مقاله -
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30 - بررسی ویژگیهای اپتیکی فازهای فشار بالای HgTe با استفاده از نظریۀ تابعی چگالی
حمداله صالحی زینب ایزدیدر این مقاله خواص اپتیکی ترکیب تلوراید جیوه نظیر تابع دیالکتریک ؛ ضرایب شکست و ضریب خاموشی استفاده از تقریبهای مختلف در سه فاز بلند روی، هگزاگونال و اورتورومبیک مورد بررسی قرار گرفته است. محاسبات با استفاده از روش شبه پتانسیل در چارچوب نظریۀتابعی چگالی و با استفاده از چکیده کاملدر این مقاله خواص اپتیکی ترکیب تلوراید جیوه نظیر تابع دیالکتریک ؛ ضرایب شکست و ضریب خاموشی استفاده از تقریبهای مختلف در سه فاز بلند روی، هگزاگونال و اورتورومبیک مورد بررسی قرار گرفته است. محاسبات با استفاده از روش شبه پتانسیل در چارچوب نظریۀتابعی چگالی و با استفاده از نرمافزار کوانتوم اسپرسو صورت گرفته است. نتایج حاصل از سهم موهومی تابع دی الکتریک نشان دهندۀ مطابقت گاف اپتیکی با گاف نواری می باشد. هم چنین نتایج حاصل از پارامترهای اپتیکی برای دو فاز بلندروی و هگزاگونال ترکیب تلورایدجیوه نشان دهندۀ این مطلب است که این ترکیب در فاز بلندروی دارای ضریب شکست 413/3 و در فاز هگزاگونال در راستای و به ترتیب دارای ضریب شکست 192/3 و 339/3 می باشد. دلیل بیشتر بودن ضریب شکست در فاز بلندروی به هگزاگونال را می توان به خاصیت شبه فلزی این ترکیب نسبت داد. در این مقاله خواص اپتیکی ترکیب تلوراید جیوه نظیر تابع دیالکتریک ؛ ضرایب شکست و ضریب خاموشی استفاده از تقریبهای مختلف در سه فاز بلند روی، هگزاگونال و اورتورومبیک مورد بررسی قرار گرفته است. محاسبات با استفاده از روش شبه پتانسیل در چارچوب نظریۀتابعی چگالی و با استفاده از نرمافزار کوانتوم اسپرسو صورت گرفته است. نتایج حاصل از سهم پرونده مقاله -
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31 - Dynamic Modelling and Control of a Dielectric Elastomer Actuator with Two Degrees of Freedom
Yaser Hesari Shahram Etemadi HaghighiDielectric elastomer actuators are capable of creating multi degrees of freedom in a single joint. In this paper, a double-cone dielectric elastomer actuator is assumed as a planar joint with two degrees of freedom. Because of theoretical complexities, mathematical form چکیده کاملDielectric elastomer actuators are capable of creating multi degrees of freedom in a single joint. In this paper, a double-cone dielectric elastomer actuator is assumed as a planar joint with two degrees of freedom. Because of theoretical complexities, mathematical formulation of dynamic equations is too complicated. To obtain the dynamic equations of motion, at first, experimental charts are used. At this stage forms of relations between displacements, voltages, forces and moments are proposed, and coefficients are optimized to keep the difference between experimental and estimated charts in minimum. Then dynamic equations of motion are derived based on Newton-Euler method, and state-space form of equations of the joint are obtained. As a second objective, joint stabilization around working point is considered. To stabilize the joint against external loads, or initial dislocations, a regulator controller is designed. The joint is over actuated. So using constraint equations, control rule is extracted and simulated. Simulations show successful performance around the working point. پرونده مقاله -
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32 - Electrical Discharges: An Emerging Modality in Sterilization, Disinfection, and Therapeutics
Soumyadeep Sarkar Niharika Verma Pawan TiwariElectrical discharges are the key mechanism to the generation of atmospheric pressure plasmas which are further classified as equilibrium and non-equilibrium plasmas, also referred to as thermal and non-thermal plasmas. The technological advancement of non-thermal plasm چکیده کاملElectrical discharges are the key mechanism to the generation of atmospheric pressure plasmas which are further classified as equilibrium and non-equilibrium plasmas, also referred to as thermal and non-thermal plasmas. The technological advancement of non-thermal plasma has extended its potential clinical non-invasive applications in a multitude of disciplines such as dermatology, ophthalmology and oncology, etc. to bolster tissue generation, refraction error correction and necrosis of the cancerous cells in the domain of plasma medicine, respectively. A fundamental on the various types of discharges and their mechanism is investigated. A perspective on the application of non-thermal plasmas in the domains such as sterilization and disinfection is presented in this review. We have focused on the plasma therapeutics and its significance as a clean and dry therapy to treat superficial skin diseases via the mechanism of proliferation of basal skin cells and prothrombin stimulation to cauterize the blood through Argon Plasma generated by Argon Plasma Coagulator. We propose to fabricate atmospheric pressure plasma devices and understanding of the associated plasma radicals that aids in the activation of biochemical and biomolecular reactions to treat the cutaneous and sub-cutaneous diseases. پرونده مقاله -
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33 - Evaluation of Breast Tumor with Antipodal Vivaldi Antenna
Emine AVŞAR AYDINSubsurface scanning problems, which both it is one of microwave imaging techniques and there are applications in various fields, has become a very interesting topic today. Many methods have been developed to detect cancer cells. The electrical properties of malignant ca چکیده کاملSubsurface scanning problems, which both it is one of microwave imaging techniques and there are applications in various fields, has become a very interesting topic today. Many methods have been developed to detect cancer cells. The electrical properties of malignant cancer cells compared to normal cells indicate significant differences at microwave frequencies. Since breast tissue according to such as brain and muscle tissues is permeable than these tissues, this case supports the idea of imaging of cancerous cells in the microwave range. Various techniques such as mammography for breast cancer diagnosis are inadequate in detecting malignant cells, have high cost, and also patients are exposed harmful rays. Because of these, it is not a desirable situation. Therefore, non-ionizing electromagnetic waves used to detect cancerous cells in the human body has been widely used in biomedical applications nowadays. In this paper, both an antipodal Vivaldi antenna with enhanced bandwidth and a 3D breast structure which has different permittivity and conductivity is modelled in CST software simulation tool to solve electromagnetic field values. Return loss, VSWR, and radiation pattern characteristics which are significant antenna parameters are simulated and obtained whether the antenna possess an efficient characteristic or not. Also, electric field values over the breast tissue with tumor and without tumor are evaluated. پرونده مقاله -
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34 - اثر پلاسمای سرد اتمسفری بر میزان رشد و قدرت تشکیل بیوفیلم در استافیلوکوکوس اورئوسهای جداشده از شیر گاو مبتلا به ورم پستان
فرهاد جهاندیده جلال شایق سمیه حسین زادهاستافیلوکوکوس اورئوس بهعنوان یکی از باکتری های مهم بیماری زا در صنعایع شیر است که قادر به تولید بیوفیلم می باشد. بیوفیلم تولید شده توسط این باکتری باعث مقاومت آن در برابر عوامل ضدمیکروبی میگردد. غیرفعال کردن میکروارگانیسم ها با استفاده از پلاسمای سرد اتمسفری یکی از رو چکیده کاملاستافیلوکوکوس اورئوس بهعنوان یکی از باکتری های مهم بیماری زا در صنعایع شیر است که قادر به تولید بیوفیلم می باشد. بیوفیلم تولید شده توسط این باکتری باعث مقاومت آن در برابر عوامل ضدمیکروبی میگردد. غیرفعال کردن میکروارگانیسم ها با استفاده از پلاسمای سرد اتمسفری یکی از روش های جدید در صنعایع غذایی می باشد. در این مطالعه جهت بررسی اثر ضدباکتریایی و ضدبیوفیلمی پلاسمای سرد اتمسفری، از دستگاه تخلیه سد دیالکتریک استفاده شد. تعداد 20 جدایه استافیلوکوکوس اورئوس بهدستآمده از شیر گاوهای مبتلا به ورمپستان بالینی، در بازه های زمانی 5 تا 20 ثانیه در معرض پلاسما قرارگرفت و اثر ضدباکتریایی آن با اندازه گیری قطر هاله مهار رشد محاسبه شد. برای ارزیابی اثرات ضدبیوفیلمی، جدایه ها بهمدت 5 ثانیه تحت تیمار با پلاسما قرار گرفتند و پس از 24 ساعت میزان تشکیل بیوفیلم بررسی شد. نتایج نشان داد که با افزایش زمان شارش پلاسما بر جدایه ها، کاهش قابلتوجهی در میزان رشد باکتری ها مشاهده میشود. همچنین آنالیز آماری نتایج حاصل از الایزا ریدر نشان داد که در معرض قرارگیری جدایه ها با پلاسما بهطور معنی داری (p < 0.05)باعث کاهش تولید بیوفیلم شده است. این نتایج حاکی از آن است که پلاسما می تواند جایگزین مناسبی برای روش های آلودگی زدایی حرارتی باشد. با اینحال، کاربرد آن مستلزم انجام مطالعات بیشتر با هدف تعیین شدت و مدتزمان مواجهه میکروارگانیسم ها با پلاسما است. پرونده مقاله -
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35 - Effect of morphology and nonbounded interface on dielectric properties of plasma sprayed BaTiO3 Coating
Amirhossein Pakseresht Mohamadreza Rahimipour Mohamadreza Vaezi Mehdi SalehiIn this research, BaTiO3 thick deposit has been successfully sprayed by air plasma spray. The microstructure and dielectric properties of thick films were investigated by secondary electron microscopy (SEM) and LCR meter respectively. XRD measurement was carried out on چکیده کاملIn this research, BaTiO3 thick deposit has been successfully sprayed by air plasma spray. The microstructure and dielectric properties of thick films were investigated by secondary electron microscopy (SEM) and LCR meter respectively. XRD measurement was carried out on plasma sprayed BaTiO3. The results illustrate differences in the crystal structure between plasma sprayed coatings and feed stock powders. The as deposited films were mainly crystalline with small amount of an amorphous second phase. The amount of crystalline to amorphous phases was found to be critically dependent upon the degree of melting of feed stock powders. The as-deposited BaTiO3 films had maximum dielectric constant as high as 85 at room temperature. Upon annealing in air at 1050 oC, the dielectric constant increased to165. Increasing in dielectric constant was attributed to the crystallization of the amorphous phase. The dielectric constant of BaTiO3 thick films produced by plasma spray was lower than that of sintering ceramic. Reduction in dielectric properties of deposited films was related to splats interface and lamellar structure of plasma sprayed coatings. پرونده مقاله -
دسترسی آزاد مقاله
36 - Influence analysis of dielectric pocket on ambipolar behavior and high-frequency performance of dual material gate oxide stack -double gate Nano-Scale TFET
Melisa Ebrahimnia Seyed Ali Sedigh Ziabari Azadeh Kiani-sarkalehIn this paper, a new Nano-Scale structure of dual material gate oxide stack-double gate TFET (DMGOS-DG TFET) with the inclusion of the dielectric pocket (DP) in the drain region is proposed. Hence the gate consists of three parts, named M1, M2, and M3 with work function چکیده کاملIn this paper, a new Nano-Scale structure of dual material gate oxide stack-double gate TFET (DMGOS-DG TFET) with the inclusion of the dielectric pocket (DP) in the drain region is proposed. Hence the gate consists of three parts, named M1, M2, and M3 with work functions ϕM1, ϕM2, and ϕM3 respectively. The work function engineering with the gate oxide stack (SiO2 as the bottom layer and HfO2 as the top layer) improves ON current, leakage current, and ambipolar behavior. In addition, the dielectric pocket (DP) has been used in the drain region to achieve better ambipolar performance. Moreover, it is found that in comparison with the low-k DP (SiO2), the presence of the high-k DP (HfO2) provides a lower ambipolar current due to the greater depletion width in the drain region. Furthermore, the ambipolar behavior of the DP-DMGOS-DG TFET structure has been investigated by changing the length and thickness of the high-k DP. Finally, the comparative analysis of DMGOS-DGTFET and high-k DP-DMGOS-DG TFET on high-frequency performance reveals that DP inclusion reduces the gate-to-drain capacitance, which leads to the improved cut-off frequency. پرونده مقاله -
دسترسی آزاد مقاله
37 - شناسایی خواص تشدیدگرهای دیالکتریک با استفاده از روش انتگرال کانتور چندمدی
علی هاشمی علی بناییروش انتگرال کانتور چندمدی یکی از روشهای تحلیل و طراحی مدارهای موجبری صفحهH- است. این روش تأثیر مدهای مرتبه بالاتر غیرانتشاری را که به دلیل وجود ناپیوستگی در ساختار موجبری ایجاد شده و در نزدیکی ناپیوستگی انرژی قابل ملاحظهای دارند، در نظر میگیرد. این ویژگی موجب بالا رفت چکیده کاملروش انتگرال کانتور چندمدی یکی از روشهای تحلیل و طراحی مدارهای موجبری صفحهH- است. این روش تأثیر مدهای مرتبه بالاتر غیرانتشاری را که به دلیل وجود ناپیوستگی در ساختار موجبری ایجاد شده و در نزدیکی ناپیوستگی انرژی قابل ملاحظهای دارند، در نظر میگیرد. این ویژگی موجب بالا رفتن دقت روش در تحلیل و یا طراحی مدارهای موجبری با ساختار پیچیده میشود.در این مقاله قصد داریم از توانمندی این روش در شناسایی خواص تشدیدگرهای دیالکتریک مانند فرکانس تشدید و ثابت دیالکتریک استفاده کنیم تا طراحی فیلترهای DR با دقت بالاتری انجام گرفته و نیاز به بهینهسازی و تنظیمات نهایی فیلتر را به حداقل برساند. مقایسه نتایج روش پیشنهادی با نتایج حاصل از سایر روشها، دقت روش پیشنهادی را ارزیابی خواهد کرد. پرونده مقاله -
دسترسی آزاد مقاله
38 - Effect of Impulse Voltage on Partial Discharge of Oil and Paper - Oil Insulators Containing Air Cavity
Seyed Mohammad Hassan Hosseini Roya ShmsaliIn power systems, usually by lightning strikes or switching operation, impulse voltage is produced. This paper reviews the effect of high impulse voltage on the PD parameters. In recent years, numerous studies on PD in the insulation, under the impulse has been done. De چکیده کاملIn power systems, usually by lightning strikes or switching operation, impulse voltage is produced. This paper reviews the effect of high impulse voltage on the PD parameters. In recent years, numerous studies on PD in the insulation, under the impulse has been done. Despite the use of power equipment and tools, switching impulse is created in the system. So, studies on PD activity with the initiation and end voltage PD in insulators have been investigated. However, the combination of PD characteristics with AC and impulse has not been studied in many studies so far. Unlike previous studies, in this paper, along with the impulse voltage, the AC voltage effects are also considered. On the other hand, dielectric characteristics show the quality of insulation in terms of the soundness or deterioration of equipment over time. The deterioration and aging of equipment can be due to electrical stresses such as alternating current PDs or transient stresses or due to environmental pressures and temperature or mechanical pressures. At this point, the effect of the PD alternating current (AC) on paper combination insulation oil dielectric frequency response equipment is investigated. In this review, a brief history of the performance of insulation against partial electrical discharge is addressed, and the finite element method software (Maxwell) is used to simulate partial electrical discharge for objects that are particularly sharp. پرونده مقاله -
دسترسی آزاد مقاله
39 - EFFECT OF ELECTRIC FIELD ON PD ACTIVITY AND DAMAGE INTO SOLID DIELECTRIC MATERIALS
Alireza GanjoviAbstract– In this paper, the effect of applied electric field on the damage due to partial discharges activity into the surroundings dielectrics of a narrow channel encapsulated within the volume of a dielectric material is evaluated using a kinetic model based on چکیده کاملAbstract– In this paper, the effect of applied electric field on the damage due to partial discharges activity into the surroundings dielectrics of a narrow channel encapsulated within the volume of a dielectric material is evaluated using a kinetic model based on Particle in Cell - Monte Carlo Collision (PIC-MCC) model. After application of an electric field across a dielectric material which contains a narrow channel, repeated ionization process starts in the gaseous medium of narrow channel. Charged particles, especially electrons, gain energy from the electric field across narrow channel and cause damage into dielectric surfaces of narrow channel on impact. The dependence of the electron energy distribution function (EEDF) on the applied electric field is studied. It isseen that, during PD activity within narrow channel, the damage to the surrounding dielectrics and consequently the surface conductivity increases. These estimations are performed based on the number of C-H bond-scissions produced by the impacting electrons of a single PD pulse. Based on this technique, the consequent damage into the solid dielectric and the time required to increase surface conductivity is computed. The formation of acid molecules due to interaction of PD pulse with polymer surface in presence of air and humidity causes changes in the surface conductivity of the surrounding dielectrics of the narrow channels. پرونده مقاله -
دسترسی آزاد مقاله
40 - Optical and Dielectric studies in zirconium(IV) tungstate nanoparticles prepared by chemical coprecipitation method
Beena Bhaskaran Manoj Sadanandan,Nanoparticles of zirconium(IV) tungstate are prepared by chemical co-precipitation method. Thecharacterizations have been carried out by TG/DTA, DSC, AFM, XRD, FTIR and UV-Vis spectrum. PLspectrum shows two emission bands at 350 nm and at 477 nm. The effects of frequenc چکیده کاملNanoparticles of zirconium(IV) tungstate are prepared by chemical co-precipitation method. Thecharacterizations have been carried out by TG/DTA, DSC, AFM, XRD, FTIR and UV-Vis spectrum. PLspectrum shows two emission bands at 350 nm and at 477 nm. The effects of frequency on the dielectricbehavior and ac electrical conductivity have been studied. The dielectric constant is found to be 119.43 at1MHz. The ac conductivity is 7.29x10-8S/cm. پرونده مقاله -
دسترسی آزاد مقاله
41 - بررسی تأثیر دوپنت WO3 بر رفتار سینتر، ریز ساختار و فاکتور اتلاف دیالکتریکهای Ba(〖Co〗_(1⁄3) 〖Nb〗_(2⁄3))O_3
نگین مزروعی احمد صیادی شهرکیدر پژوهش حاضر اثر افزودن WO3 بر روی سینتر، ریزساختار و اتلاف مایکروویو دیالکتریک ترکیبهای Ba(Co1/3Nb2/3)O3 بررسی شد. سرامیکها(1-x) Ba(Co1/3Nb2/3)O3 – (x) WO3 که 02/0-0=x، به روش مرسوم حالت جامد با سینتر در دمای ºC 1300-1450 به مدت 10 ساعت تهیه شدند. حد حلا چکیده کاملدر پژوهش حاضر اثر افزودن WO3 بر روی سینتر، ریزساختار و اتلاف مایکروویو دیالکتریک ترکیبهای Ba(Co1/3Nb2/3)O3 بررسی شد. سرامیکها(1-x) Ba(Co1/3Nb2/3)O3 – (x) WO3 که 02/0-0=x، به روش مرسوم حالت جامد با سینتر در دمای ºC 1300-1450 به مدت 10 ساعت تهیه شدند. حد حلالیت WO3 در ساختار پروسکایتی Ba(Co1/3Nb2/3)O3 و تشکیل نوع فازهای ثانویه توسط پراش اشعه ایکس (XRD) مطالعه شد. همچنین تغییرات درجه نظم کاتیونی 1:2 با دوپ کردن WO3 با روش پالایش ریتویلد به طور دقیق ارزیابی شد. علاوه براین مطالعات ریزساختاری به کمک میکروسکوپ الکترونی روبشی انجام شد. نتایج به دست آمده توسط آنالیز XRD حد حلالیت WO3 در شبکه Ba(Co1/3Nb2/3)O3 را مقدار 02/0=x نشان داد ولی ارزیابیهای SEM نشان داد که حتی اضافه کردن مقدار 002/0=x نیز باعث ایجاد فازهای ثانویه با ترکیبهای شیمیایی BaWO4 و Ba9CoNb14O45 در این سرامیکها میشود. از طرف دیگر، محاسبات پالایش ریتویلد کاهش درجه نظم کاتیونی 1:2 را با افزایش مقدار دوپنت WO3 نشان داد، بهطوری که درجه نظم کاتیونی با افزایش x از 0 تا 02/0 از مقدار % 95 به % 59 کاهش یافت. فاکتور کیفیت (عکس اتلاف دیاکتریک) سرامیکهای دوپ شده با استفاده از روش تشدید دیالکتریک تعیین شد و مشاهده شد که فاکتور کیفیت سرامیکهای (1-x) Ba(Co1/3Nb2/3)O3 – (x) WO3با افزایش مقدار x به شدت کاهش یافته بهطوری که برای سرامیک دوپ نشده مقدار Q×f برابر با GHz 61000 بوده ولی سرامیکها با ترکیب 02/0=x از خود پیک رزونانس نشان ندادند که به معنی افزایش بسیار زیاد اتلاف مایکروویو دیالکتریک این ترکیبها میباشد. پرونده مقاله -
دسترسی آزاد مقاله
42 - بهینهسازی خواص مکانیکی و دیالکتریک بوسیله کنترل تراکمپذیری و ریزساختار در سرامیکهای نیترید سیلیسیم تهیه شده به روش پرس داغ
سیدسلمان سیدافقهی امیرحسین کوچکی فروشانی پوریا دهقانی فرهود حیدریسرامیکهای نیترید سیلیسیم موادی با خواص مکانیکی، دیالکتریک و حرارتی عالی هستند که با دارا بودن چنین ویژگیهایی یکی از کاندیدهای اصلی جهت کاربرد در شرایط محیطی دما بالا است. در این پژوهش اثر دمای تفجوشی بر کنترل ریزساختار و تراکم پذیری و بهینهسازی خواص مکانیکی و دیا چکیده کاملسرامیکهای نیترید سیلیسیم موادی با خواص مکانیکی، دیالکتریک و حرارتی عالی هستند که با دارا بودن چنین ویژگیهایی یکی از کاندیدهای اصلی جهت کاربرد در شرایط محیطی دما بالا است. در این پژوهش اثر دمای تفجوشی بر کنترل ریزساختار و تراکم پذیری و بهینهسازی خواص مکانیکی و دیالکتریک سرامیکهای نیترید سیلیسیم تهیه شده به روش پرس داغ در دماهای مختلف 1500، 1600، 1700 و 1800 درجه سانتیگراد بررسی شده است. از دستگاه میکروسکوپ الکترونی روبشی و پراش اشعه ایکس به ترتیب جهت بررسی ریزساختار و آنالیز فازهای تشکیل شده استفاده شده است. طبق الگوی پراش حاصل از پرتو ایکس و رابطه گازارا-مسیر، در نمونههای سینتر شده در دمای 1600 و1700 درجه سانتیگراد همه فاز آلفا به بتا تبدیل شده و در نمونه سینتر شده در دمای 1500 درجه سانتیگراد میزان تبدیل 95.45% بوده است. نتایج حاکی از آن است که افزایش دمای تفجوشی از1500 به 1800 درجه سانتیگراد منجر به درشتتر شدن دانههای میلهای شکل و دستیابی به ریزساختار دوگانه شده و قطر متوسط دانهها از 0.7 میکرومتر به 1.34 میکرومتر افزایش یافته است. نمونه سینتر شده در دمای 1500درجه سانتیگراد با دارا بودن کمترین مقدار قطر متوسط ( 0.7 میکرومتر) در بین سایر نمونهها، بیشترین مقدار استحکام خمشی 9.5 ± 550 مگاپاسکال را به خود اختصاص داده است. با افزایش اندازه متوسط دانهها و کاهش نسبت فازی α/β در اثر افزایش دمای تفجوشی، میانگین ثابت دیالکتریک و تانژانت اتلاف نمونهها به ترتیب از 4.5 به 9.2 و از 0.099 به 0.22 افزایش یافته است. پرونده مقاله
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