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Relative Dielectric Permittivity Variations during Compaction as a Mean of Compaction Quality Control: Case Study on Laterite Samples from Senegal
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作者 Mapathé Ndiaye Makhaly Ba +1 位作者 Teophile Kiendrebeogo Linda E. Gaffo Foudjo 《International Journal of Geosciences》 CAS 2023年第2期238-250,共13页
This study explores an alternative to the classical use of direct methods, as water content and dry density measurements, for compaction quality control. For this purpose, the dielectric properties of lateritic materi... This study explores an alternative to the classical use of direct methods, as water content and dry density measurements, for compaction quality control. For this purpose, the dielectric properties of lateritic materials are determined by radar method and are compared with the permittivity determined from the Topp formula and from the CRIM model. This approach allowed to establish a relationship between the geotechnical properties determined during compaction such as dry density, water content or porosity with dielectric permittivity. The obtained results made it possible to determine an optimum dielectric permittivity corresponding to the optimum dry density and the optimum water content that could be used for non-destructive in situ compaction testing. Such an approach should improve the implementation and effectiveness of in situ compaction quality control of geotechnical infrastructures. 展开更多
关键词 LATERITE Proctor Water Content Dry Density dielectric permittivity
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Enhanced dielectric permittivity of graphite oxide/polyimide composite films 被引量:3
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作者 李俊 王亚 李衡峰 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第11期2747-2753,共7页
Graphite oxide(GO) was prepared by the pressurized oxidation method and incorporated into polyimide(PI) matrix to fabricate high-k composite films by in-situ polymerization and subsequent thermal treatment. The result... Graphite oxide(GO) was prepared by the pressurized oxidation method and incorporated into polyimide(PI) matrix to fabricate high-k composite films by in-situ polymerization and subsequent thermal treatment. The results show that the as-prepared GO had good dispersion and compatibility in PI matrix due to the introduction of abundant oxygen-containing functional groups during the oxidation. The residual graphitic domains and the thermal treatment induced reduction of GO further enhanced the dielectric permittivity of the resulting GO–PI composites. The dielectric permittivity of the GO–PI composites exhibited a typical percolation behavior with a percolation threshold of 0.0347 of volume ratio and a critical exponent of 0.837. Near the percolation threshold, the dielectric permittivity of the GO–PI composite increased to 108 at 10~2 Hz and was 26 times that of the pure PI. 展开更多
关键词 graphite oxide pressurized oxidation POLYIMIDE dielectric permittivity PERCOLATION
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Dielectric Permittivity of Rigid Rapeseed Oil Polyol Polyurethane Biofoams and Petrochemical Foams at Low Frequencies 被引量:1
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作者 Ilze Beverte Vairis Shtrauss +4 位作者 Aldis Kalpinsh Uldis Lomanovskis Ugis Cabulis Irina Sevastyanova Sergejs Gaidukovs 《Journal of Renewable Materials》 SCIE EI 2020年第9期1151-1170,共20页
Early investigations of dielectric permittivity of rigid polyurethane foams at low frequencies were made on petrochemical-origin foams,mainly by means of parallel plate capacitors.In the present investigation biopolyo... Early investigations of dielectric permittivity of rigid polyurethane foams at low frequencies were made on petrochemical-origin foams,mainly by means of parallel plate capacitors.In the present investigation biopolyol was synthesized from Latvia-grown rapeseeds’oil by the transesterification method with triethanolamine,in an environmentally friendly process,without emission of harmful substances,at temperatures 175℃±5℃.Rigid,closed-cell rapeseed oil polyol polyurethane biofoams and petrochemical foams were made ensuring content of the renewable rapeseed oil polyol in ready foams 27 wt.%–29 wt.%.Dielectric permittivity of the polyurethane foams and the underlying monolithic petrochemical-origin polyurethane and biopolyurethane was measured with a non-destructive dielectric spectrometer equipped with a capacitive sensor of one-side access type at 16 discrete frequencies distributed geometrically over the band 10 Hz,…,330 kHz.Permittivity value of the gaseous phase in the closed-cells was estimated to beεg≈1.001 that corresponds to the values,characteristic for the most of gases.Dielectric permittivity of petrochemical polyurethane foams and the mentioned biofoams was compared with permittivity of polyurethane foams from industrial producers Sika JSC and General Plastics Manufacturing Co.Polyurethane foams of the developed formulation exhibit competitive,low dielectric permittivity,not exceeding that of the foams from industrial producers:petrochemical foams up to 550 kg/m^(3) and the mentioned biofoams,comprising the renewable rapeseed oil polyol,up to densities 230–250 kg/m^(3).Considering petrochemical-origin polyurethane foams as a heterogeneous media“Polymer—gaseous phase”,the applicability of the rule of mixture and Maxwell–Garnett equation to model mathematically the dependence of effective dielectric permittivity on the volume fraction of phases was showed. 展开更多
关键词 Polyurethane foams rapeseed oil polyol biofoams dielectric permittivity capacitive sensor one-side access low frequencies
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A new equation for dielectric permittivity of saturated soils based on polarization mechanics
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作者 Ren-peng CHEN Yun-min CHEN +2 位作者 Wei XU Zhi-gang LIANG Wei FENG 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第3期293-302,共10页
Based on polarization mechanisms, such as electronic, ionic and orientational polarizations, a new equation for dielectric permittivity of soil is proposed to interpret the dielectric behavior of a mixture like soil, ... Based on polarization mechanisms, such as electronic, ionic and orientational polarizations, a new equation for dielectric permittivity of soil is proposed to interpret the dielectric behavior of a mixture like soil, in terms of polarization process of its components and the interactions between its components. The dielectric permittivity is expressed in terms of a fre-quency-dependent part and a frequency-independent part. These two parts correspond to polarizations occurred at different fre-quency range. It is a new volumetric mixing model with theoretical background. Based on time domain reflectometry (TDR) measurements of saturated soil samples and test data from literature, comparisons of this model with some well established mixing models show that the curves for saturated sand soils and slurries resulted from the new equation, which agree well with TDR measurements, are close to those calculated from Birchak's model. 展开更多
关键词 dielectric permittivity Saturated soils POLARIZATION Time domain reflectometry (TDR)
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Wide-Temperature-Range Dielectric Permittivity Measurement under High Pressure
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作者 Zhen Yuan Jin-Long Zhu +4 位作者 Shao-Min Feng Chang-Chun Wang Li-Juan Wang Qing-Qing Liu Chang-Qing Jin 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第4期13-17,共5页
Two measurement systems are developed for in-situ dielectric property measurement under high pressure in a wide-temperature range from 77K to 1273 K. The high-temperature system ranging from room temperature up to 127... Two measurement systems are developed for in-situ dielectric property measurement under high pressure in a wide-temperature range from 77K to 1273 K. The high-temperature system ranging from room temperature up to 1273K is equipped with a hexahedron anvils press, while the low-temperature system ranging from liquid nitrogen temperature to normal condition is equipped using the piston cylinder setup with a specially designed sample chamber. Using these configurations, the dielectric property measurement of ferroelectrie BaTiO3 and multiferroie Tm0.5Gd0.5MnO3 compounds are demonstrated, which proves the validity of the systems through the tuning of the polarization and phase transition boundary by high pressure. These two systems will be equally applicable to a wide variety of electronic and transport property measurements of insulators, semiconductors, as well as battery materials. 展开更多
关键词 der Wide-Temperature-Range dielectric permittivity Measurement under High Pressure BTO
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A New Numerical Method for Calculation of Complex Dielectric Permittivity
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作者 Long Yunliang & Jiang Hongyan(Dept. of Electronics, Zhongshan University, Guangzhou 510275, P. R. China) (This project was supported partly by the National Natural Science Foundation of China (49604058) andpartly by the Natural Science Foundation of Guang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1998年第4期41-44,共4页
In this paper, a new numerical method-Kuhn algorithm with contour integral-is intrroduced and used to calculate the complex dielectric permittivities of materials from the short-circuitedwaveguide measurements. Some n... In this paper, a new numerical method-Kuhn algorithm with contour integral-is intrroduced and used to calculate the complex dielectric permittivities of materials from the short-circuitedwaveguide measurements. Some numerical results are given to verify the validity and efficiency ofthe new numerical method and the complex dielectric permittivities of materials calculated by thenew numerical method are quite identical with the results given by other works. 展开更多
关键词 Complex dielectric permittivity Kuhn algorithm Contour integral
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Dielectric permittivity of dusty plasma in the Earth's mesosphere
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作者 Hui Li Jian Wu 《Earth and Planetary Physics》 CSCD 2021年第1期117-120,共4页
This paper deals with the dielectric permittivity of dusty plasma in the earth’s mesosphere.We give expressions for the complex dielectric permittivity of dusty plasma,taking into account the effects of the dust char... This paper deals with the dielectric permittivity of dusty plasma in the earth’s mesosphere.We give expressions for the complex dielectric permittivity of dusty plasma,taking into account the effects of the dust charging process and magnetic field.We discuss the dielectric permittivity of dusty plasma in several cases,such as high frequency approximation,parallel propagation in MF/HF band,and effects of plasma movement.Finally,the expressions are employed to study the phenomenon of radar echoes from the polar summer mesosphere.We report that dielectric permittivity caused by the dust charging process gives a radar cross section proportional to ω–4 and produces a number density of charged dust that agrees with measurements of mesopheric radar echoes. 展开更多
关键词 dusty plasma dielectric permittivity polar summer mesosphere
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Low temperature sintered giant dielectric permittivity CaCu_(3)Ti_(4)O_(12) sol-gel synthesized nanoparticle capacitors
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作者 Venkata Sreenivas Puli Shiva Adireddy +2 位作者 Manish Kothakonda Ravinder Elupula Douglas B.Chrisey 《Journal of Advanced Dielectrics》 CAS 2017年第3期14-23,共10页
This paper reports on synthesis of polycrystalline complex perovskite CaCu_(3)Ti_(4)O_(12)(as CCTO)ceramic powders prepared by a sol–gel auto combustion method at different sintering temperatures and sintering times,... This paper reports on synthesis of polycrystalline complex perovskite CaCu_(3)Ti_(4)O_(12)(as CCTO)ceramic powders prepared by a sol–gel auto combustion method at different sintering temperatures and sintering times,respectively.The effect of sintering time on the structure,morphology,dielectric and electrical properties of CCTO ceramics is investigated.Tuning the electrical properties via different sintering times is demonstrated for ceramic samples.X-ray diffraction(XRD)studies confirm perovskite-like structure at room temperature.Abnormal grain growth is observed for ceramic samples.Giant dielectric permittivity was realized for CCTO ceramics.High dielectric permittivity was attributed to the internal barrier layer capacitance(IBLC)model associated with the Maxwell–Wagner(MW)polarization mechanism. 展开更多
关键词 CCTO CUBIC giant dielectric permittivity IBLC grain growth.
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Dipole relaxation process and giant dielectric permittivity in Eu3þdoped CdMoO_(4) single crystal
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作者 B.Sawicki E.Tomaszewicz +5 位作者 T.Gron M.Berkowski M.Głowacki M.Oboz J.Kusz S.Pawlus 《Journal of Materiomics》 SCIE EI 2021年第4期845-857,共13页
Single crystal of Eu3þ-doped cadmium molybdate(Cd0.9268M0.0244Eu0.0488MoO_(4),where M denotes cationic vacancies)has been successfully grown by the Czochralski method in air and under 1 MPa.X-ray diffraction anal... Single crystal of Eu3þ-doped cadmium molybdate(Cd0.9268M0.0244Eu0.0488MoO_(4),where M denotes cationic vacancies)has been successfully grown by the Czochralski method in air and under 1 MPa.X-ray diffraction analysis indicates that as-grown single crystal exhibits tetragonal scheelite-type structure(a=b=5.16188(14)Å;c=11.2080(5)Å;space group I41/a).Eu^(3+) þions do not show long-range order and they are randomly distributed in CdMoO_(4) framework substituting Cd^(2+ )þones.UVevis diffuse reflectance measurements revealed very close optical band gap(Eg)values,i.e.-1.74 eV along[100]and[001]crystallographic directions that are twice smaller than Eg of microcrystalline pure CdMoO_(4) as well as powder Eu3þ-doped single crystal.Magnetic and electrical studies of Eu3þ-doped cadmium molybdate single crystal showed a paramagnetic and n-type semiconducting behaviour with the metal-insulator transition above 350 K along both crystallographic directions.Dielectric results analysis using the Cole-Cole fit function revealed that the dipole relaxation process has different time scale depending on the crystallographic direction and exhibits Arrhenius temperature dependence for both studied directions.This fact is accompanied by the colossal dielectric permittivity withεr>8,103.The above results are considered in the framework of narrow europium multiplets of energy comparable to thermal energy. 展开更多
关键词 SCHEELITE Single crystal Solid solution Paramagnetic behaviour Relaxation process Giant dielectric permittivity
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CONTRIBUTION OF THE INTERPHASE INTERACTION TO THE DIELECTRIC PERMITTIVITY OF COLLOID SYSTEMS
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作者 V.S.BORISOV 《Journal of Advanced Dielectrics》 CAS 2011年第2期169-178,共10页
Specific features of the dielectric response of colloid systems with electrically interacting com-ponents(polar liquid matrix and solid spherical inclusions)have been revealed.A theory was developed to describe dielec... Specific features of the dielectric response of colloid systems with electrically interacting com-ponents(polar liquid matrix and solid spherical inclusions)have been revealed.A theory was developed to describe dielectric dispersion and anisotropy of the liquid phase caused by the electric field of surface charges on the solid particles.It was found that the local dielectric permittivity in diferent directions can vary over a wide range and strongly depends on the strength of the inner field.The existence of the interphase interaction leads to the formation of thin structured liquid layers in the contact area of two phases and,therefore,to a decrease in the average dielectric permittivity of the considered system.Nonuniform structure of the polar liquid was taken into account while the derivation of a mixing formula which clearly demonstrates the contribution of the interphase interaction to the dielectric response of the investigated colloid system. 展开更多
关键词 COLLOIDS interphase interaction dielectric permittivity mixing formula
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Temperature characterization of dielectric permittivity and AC conductivity of nano copper oxide-doped polyaniline composite
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作者 L.N.Shubha P.Madhusudana Rao 《Journal of Advanced Dielectrics》 CAS 2016年第3期27-33,共7页
The polyaniline/copper oxide(PANI/CuO)nanocomposite was prepared by mixing solutions of polyaniline and copper oxide nanoparticles in dimethyl sulfoxide(DMSO).The synthesized polymer nanocomposites were characterized ... The polyaniline/copper oxide(PANI/CuO)nanocomposite was prepared by mixing solutions of polyaniline and copper oxide nanoparticles in dimethyl sulfoxide(DMSO).The synthesized polymer nanocomposites were characterized by X-ray powder diffraction(XRD),scanning electron microscope(SEM)and UV-visible spectroscopy.The characteristic peaks in XRD and UV-visible spectra confirmed the presence of CuO in the polymer structure.SEM images indicated morphological changes in the composite matrix as compared to the pristine PANI.The DC conductivity measurements were performed using two-probe method for various temperatures.AC conductivity and dielectric response of the composites were investigated in the frequency range of 10^(2)-10^(6)Hz using LCR meter.Dielectric permittivityε′(w)and dielectric loss factorε″(w)were investigated.It was observed thatε′(w)andε″(w)decrease with increase in frequency at all temperatures.At a particular frequency it is observed that bothε′(w)andε″(w)increase with increase in temperature.It was also observed that AC conductivity increased with increase in frequency and temperature. 展开更多
关键词 AC conductivity dielectric permittivity dielectric loss factor polyaniline composite
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A Short Review on Copper Calcium Titanate(CCTO) Electroceramic;Synthesis,Dielectric Properties,Film Deposition,and Sensing Application 被引量:2
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作者 Mohsen Ahmadipour Mohd Fadzil Ain Zainal Arifin Ahmad 《Nano-Micro Letters》 SCIE EI CAS 2016年第4期291-311,共21页
Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities(e) of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestab... Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities(e) of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestablished and emerging applications such as resonator,capacitor,and sensor.These applications take advantage of the unique properties achieved through the structure and properties of CCTO.This review comprehensively focuses on the primary processing routes,effect of impurity,dielectric permittivity,and deposition technique used for the processing of electroceramics along with their chemical composition and micro and nanostructures.Emphasis is given to versatile and basic approaches that allow one to control the microstructural features that ultimately determine the properties of the CCTO ceramic.Despite the intensive research in this area,none of the studies available in the literature provides all the possible relevant information about CCTO fabrication,structure,the factors influencing its dielectric properties,CCTO immobilization,and sensing applications. 展开更多
关键词 CCTO Chemical synthesis dielectric permittivity Loss factor DEPOSITION Sensitivity
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Microstructural,magnetic and dielectric performance of rare earth ion(Sm^(3+))-doped MgCd ferrites
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作者 Dandan Wen Xia Chen +4 位作者 Dasen Luo Yi Lu Yixin Chen Renpu Li Wei Cui 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第7期643-647,共5页
The combined effects of Sm^(3+)substitution together with the addition of 3 wt%Bi_(2)O_(3)endow Mg Cd ferrites with excellent magnetic permeability and dielectric permittivity.Various concentrations of Sm^(3+)(x=0,0.0... The combined effects of Sm^(3+)substitution together with the addition of 3 wt%Bi_(2)O_(3)endow Mg Cd ferrites with excellent magnetic permeability and dielectric permittivity.Various concentrations of Sm^(3+)(x=0,0.03,0.06,0.09,0.12and 0.15)were employed to modify the permeability(μ)and permittivity(ε)of the Mg Cd ferrites.X-ray diffraction,scanning electron microscopy(SEM),vibrating sample magnetometry and vector network analysis techniques were used to characterize the samples.The measurement results reveal that the ferrites processed a saturation magnetization of up to 36.8 emu/g and coercivity of up to 29.2 Oe via the conventional solid-state reaction method.The surface morphology SEM confirms that with increasing Sm^(3+)concentration,the grain shape changes from a polygon to a circle.Moreover,the dielectric permittivity can reach a value of 23.The excellent properties obtained in Sm^(3+)-substituted Mg ferrites suggest that they could be promising candidates for modern high-frequency antenna substrates or multilayer devices. 展开更多
关键词 ferrites Sm^(3+)ions SUBSTITUTION magnetic permeability dielectric permittivity
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Comprehensive studies on dielectric properties of p-methoxy benzylidene p-decyl aniline with function of temperature and frequency in planar geometry: A potential nematic liquid crystal for display devices
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作者 Pankaj Kumar Tripathi Kunwar Vikram +1 位作者 Mithlesh Tiwari Ajay Shriram 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第6期329-333,共5页
The dielectric properties of the nematic mesophase, p-methoxy benzylidene p-decyl aniline(MBDA), measured in planar geometry with a function of frequency and temperature are investigated in detail. The complex dielect... The dielectric properties of the nematic mesophase, p-methoxy benzylidene p-decyl aniline(MBDA), measured in planar geometry with a function of frequency and temperature are investigated in detail. The complex dielectric permittivity(ε' and ε'') is also studied at a bias voltage of 10 V for planar aligned sample cell of nematic mesophase. The dielectric permittivity with bias voltage attains a higher(> 2 times) value than that without bias voltage at a temperature of 56℃,which is due to the fact that the linking group of nematic molecules is internally interacted with an applied bias voltage.This is supported by observing an enhanced dielectric permittivity of nematic liquid crystal(LC) in the presence of bias voltage, which can be fully explained as the increasing of the corresponding dipole moment. The dielectric relaxation behaviors of nematic LC are also demonstrated for planar aligned sample cell. The remarkable results are observed that the relaxation frequency shifts into low frequency region with the increase of the bias voltage applied to the planar aligned sample cells. The dielectric relaxation spectra are fitted by Cole–Cole nonlinear curve fitting for nematic mesophase in order to determine the dielectric strength. 展开更多
关键词 dielectric permittivity dielectric loss relaxation frequency nematic mesogen
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Theoretical Study of Antiferrodistortive Phase Transition in Strontium Titanate
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作者 蔡玉平 韩代朝 宁如云 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2010年第2期237-240,I0002,共5页
At 105 K, strontium titanate is known to undergo an antiferrodistortive transition transform-ing from cubic to tetragonal structure as a result of the rotation of the oxygen octahedral around a cubic axe. Based on the... At 105 K, strontium titanate is known to undergo an antiferrodistortive transition transform-ing from cubic to tetragonal structure as a result of the rotation of the oxygen octahedral around a cubic axe. Based on the Curie principle, the order parameter is determined to be a third-order complete symmetry polarization tensor. To take into account of quantum effects,the dielectric permittivity is measured from Landau free energy, and the Curie Weiss-type behavior is analyzed. From crystallization chemistry viewpoint, the dielectric behavior at low temperature is connected to small radius of Sr^2+, which is much easier to move around the oxygen octahedral than Ba^2+ in BaTiO3 or Pb^2+ in PbTiO3. 展开更多
关键词 Spontaneous polarization dielectric permittivity Free energy Antiferrodis-tortive phase transition
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Evaluating some factors that affect feasility of using ground penetrating radar for landmine detection 被引量:2
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作者 Mohamed Metwaly Ahmed Ismail Jun Matsushima 《Applied Geophysics》 SCIE CSCD 2007年第3期221-230,共10页
Ground penetrating radar (GPR) is one of the promising technologies that can be used to detect landmines. Many factors may affect the ability of GPR to detect landmines. Among those factors are: 1) the type of lan... Ground penetrating radar (GPR) is one of the promising technologies that can be used to detect landmines. Many factors may affect the ability of GPR to detect landmines. Among those factors are: 1) the type of landmine material (metallic or plastic), 2) conditions of the host soil (soil texture and soil moisture), and 3) the radar frequency utilized. The impact of these factors on the ability of GPR to detect landmines is investigated by studying their effect on the dielectric permittivity contrast between the landmine and the host soil, as well as on the attenuation of the radar waves. The impact of each factor was theoretically reviewed and modeled using the Matlab and Mathcad software packages. Results of the computer modeling were correlated with GPR data acquired for metallic and plastic landmine types. It was found that the ability of GPR to detect landmines depends to a great extent on the landmine type, water content of the host soil, utilized radar frequency, and soil texture. The landmines are much easier to detect than plastic landmines for any soil conditions and any radar frequency. Increasing the soil's moisture content, regardless of soil texture, eases the detection of the plastic landmine and worsens the detection of the metallic mines. Increasing the percentage of clay in the soil causes the same effect as the moisture content. However, higher radar frequency delivers better results for landmine detection as long as the percentage of clay and the moisture content in the soil remains low. The results of this study are expected to help in selecting optimum radar antennae and data acquisition parameters depending on the landmine type and environmental conditions. 展开更多
关键词 LANDMINE dielectric permittivity GPR
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Electrical Relaxation in Mixed Alkali Bi_2O_3-K_2O-Li_2O-Fe_2O_3 Glasses 被引量:1
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作者 E.E.Shaisha Sh.F.El-Desouki +1 位作者 I.Shaltout A.A.Bahgat 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2006年第5期701-707,共7页
A new glass system (Bi2O3)50(Fe2O3)10(Li2O)x(K2O)40-x, where x changes in steps of 5 mole fraction between 0 and 40, was selected to study the electrical relaxation and the mixed alkali effect (MAE) phenomen... A new glass system (Bi2O3)50(Fe2O3)10(Li2O)x(K2O)40-x, where x changes in steps of 5 mole fraction between 0 and 40, was selected to study the electrical relaxation and the mixed alkali effect (MAE) phenomena. Measurements of ac conductivity σac, dielectric permittivity ε′ and loss factor tanδ in the frequency range of 0.12~10^2 kHz and in the temperature range of 300~650 K were carried out. The temperature dependence of the ac conductivity shows a slow increasing rate at low temperature and high frequency and a rapid increase at high temperature and low frequency. At constant temperature, the ac conductivity is found to be proportional to ω^8, where s is the frequency exponent, which is less than 1. Analysis of the conductivity data and the frequency exponent shows that the overlapping large polaron tunnelling (OLPT) model of ions is the most favorable mechanism for the ac conduction in the present glass system. The ac response, the dc conductivity and dielectric relaxation have the same activation energy and they originate from the same basic transport mechanism. The results of the dielectric permittivity show no maximum peak in the temperature and frequency range studied. This absence of maximum peak is an indication of non-ferroelectric behavior of all the studied samples. The MAE has been detected in the ac conductivity, which is the same as the classical MAE in the dc conductivity. The electrical parameters such as dielectric permittivity ε′ and real dielectric modulus M′ show a typical minimum deviation from linearity by about two orders of magnitude. The loss factor tanδ and the imaginary dielectric modulus M″ are insignificantly dependent on composition even at the same transition temperature Tg. 展开更多
关键词 dielectric permittivity dielectric modulus Loss factor Conduction mechanism MAE (mixed alkali effect)
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Novel attributes and design considerations of effective oxide thickness in nano DG MOSFETs
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作者 Morteza Charmi 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第4期387-393,共7页
Impacts of effective oxide thickness on a symmetric double-gate MOSFET with 9-nm gate length are studied, using full quantum simulation. The simulations are based on a self-consistent solution of the two-dimensional ... Impacts of effective oxide thickness on a symmetric double-gate MOSFET with 9-nm gate length are studied, using full quantum simulation. The simulations are based on a self-consistent solution of the two-dimensional (2D) Poisson equation and the Schr6dinger equation within the non-equilibrium Green's function formalism. Oxide thickness and gate dielectric are investigated in terms of drain current, on-off current ratio, off current, sub-threshold swing, drain induced barrier lowering, transconductance, drain conductance, and voltage. Simulation results illustrate that we can improve the device performance by proper selection of the effective oxide thickness. 展开更多
关键词 DG-MOSFET effective oxide thickness non-equilibrium Green's function oxide thickness gate dielectric permittivity
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Lattice dynamics properties of chalcopyrite ZnSnP_2:Density-functional calculations by using a linear response theory
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作者 虞游 董玉静 +3 位作者 沈艳红 赵国栋 郑小林 盛佳南 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第4期307-312,共6页
We present a first-principles study of the structural,dielectric,and lattice dynamical properties for chalcopyrite semiconductor ZnSnP2.The structural properties are calculated using a plane-wave pseudopotential metho... We present a first-principles study of the structural,dielectric,and lattice dynamical properties for chalcopyrite semiconductor ZnSnP2.The structural properties are calculated using a plane-wave pseudopotential method of densityfunctional theory.A linear response theory is used to derive Born effective charge tensors for each atom,dielectric constants in low and high frequency limits,and phonon frequencies.We calculate all zone-center phonon modes,identify Raman and infrared active modes,and report LO-TO splitting of the infrared modes.The results show an excellent agreement with experiment and propose several predictive behaviors. 展开更多
关键词 PHONON Born effective charge dielectric permittivity linear response theory
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PROPAGATION OF ELECTROMAGNETIC WAVE IN THE THREE PHASES SOIL MEDIA
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作者 陈云敏 边学成 +1 位作者 陈仁朋 梁志刚 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2003年第6期691-699,共9页
The fundamental parameters such as dielectric permittivity and magnetic permeability are required to solve the propagation of electromagnetic wave (EM Wave) in the soil. Based on Maxwell equations, the equivalent m... The fundamental parameters such as dielectric permittivity and magnetic permeability are required to solve the propagation of electromagnetic wave (EM Wave) in the soil. Based on Maxwell equations, the equivalent model is proposed to calculate the dielectric permittivity of mixed soil. The results of calculation fit the test data well and will provide solid foundation for the application of EM wave in the soil moisture testing,CT analyzing of soil and the inspecting of geoenvironment. 展开更多
关键词 electromagnetic wave dielectric permittivity SOIL wave propagation
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