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  Subjects -> PHYSICS (Total: 750 journals)
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PHYSICS (543 journals)                  1 2 3 4 5 6 | Last

Acta Acustica united with Acustica     Full-text available via subscription   (Followers: 7)
Acta Mechanica     Hybrid Journal   (Followers: 15)
Advanced Composite Materials     Hybrid Journal   (Followers: 14)
Advanced Functional Materials     Hybrid Journal   (Followers: 36)
Advanced Materials     Hybrid Journal   (Followers: 367)
Advances in Condensed Matter Physics     Open Access   (Followers: 6)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 3)
Advances in Geophysics     Full-text available via subscription   (Followers: 4)
Advances in High Energy Physics     Open Access   (Followers: 11)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 1)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 15)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 14)
Advances in OptoElectronics     Open Access   (Followers: 3)
Advances In Physics     Hybrid Journal   (Followers: 7)
Advances in Physics Theories and Applications     Open Access   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 8)
Advances in Synchrotron Radiation     Hybrid Journal   (Followers: 1)
AIP Advances     Open Access   (Followers: 4)
AIP Conference Proceedings     Full-text available via subscription   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 29)
American Journal of Condensed Matter Physics     Open Access   (Followers: 2)
American Journal of Signal Processing     Open Access   (Followers: 7)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 1)
Annalen der Physik     Hybrid Journal   (Followers: 2)
Annales Geophysicae (ANGEO)     Open Access   (Followers: 3)
Annales Henri PoincarĂ©     Hybrid Journal   (Followers: 1)
Annales UMCS, Physica     Open Access  
Annals of Nuclear Medicine     Hybrid Journal   (Followers: 3)
Annals of Physics     Hybrid Journal   (Followers: 2)
Annals of West University of Timisoara - Physics     Open Access  
Annual Reports on NMR Spectroscopy     Full-text available via subscription   (Followers: 1)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Annual Review of Condensed Matter Physics     Full-text available via subscription   (Followers: 1)
Annual Review of Materials Research     Full-text available via subscription   (Followers: 4)
APL Materials     Open Access   (Followers: 4)
Applied Composite Materials     Hybrid Journal   (Followers: 9)
Applied Physics A     Hybrid Journal   (Followers: 9)
Applied Physics Frontier     Open Access   (Followers: 1)
Applied Physics Letters     Hybrid Journal   (Followers: 25)
Applied Physics Research     Open Access   (Followers: 6)
Applied Physics Reviews     Hybrid Journal   (Followers: 7)
Applied Radiation and Isotopes     Hybrid Journal   (Followers: 5)
Applied Remote Sensing Journal     Open Access   (Followers: 9)
Applied Spectroscopy     Full-text available via subscription   (Followers: 12)
Applied Spectroscopy Reviews     Hybrid Journal   (Followers: 2)
Archive for Rational Mechanics and Analysis     Hybrid Journal   (Followers: 3)
Astronomy & Geophysics     Hybrid Journal   (Followers: 1)
Astrophysical Journal Letters     Full-text available via subscription   (Followers: 3)
Atoms     Open Access  
Attention, Perception & Psychophysics     Full-text available via subscription   (Followers: 6)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Axioms     Open Access  
Bangladesh Journal of Medical Physics     Open Access  
Bauphysik     Hybrid Journal   (Followers: 1)
Biomaterials     Hybrid Journal   (Followers: 30)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 15)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Biomedical Imaging and Intervention Journal     Open Access   (Followers: 5)
Biophysical Reviews     Hybrid Journal  
Biophysical Reviews and Letters     Hybrid Journal   (Followers: 3)
BMC Biophysics     Open Access   (Followers: 7)
BMC Nuclear Medicine     Open Access   (Followers: 5)
Brazilian Journal of Physics     Hybrid Journal  
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Bulletin of Materials Science     Open Access   (Followers: 39)
Bulletin of the Atomic Scientists     Full-text available via subscription   (Followers: 4)
Bulletin of the Lebedev Physics Institute     Hybrid Journal   (Followers: 1)
Bulletin of the Russian Academy of Sciences: Physics     Hybrid Journal  
Caderno Brasileiro de Ensino de FĂ­sica     Open Access  
Canadian Journal of Physics     Full-text available via subscription   (Followers: 1)
Cells     Open Access   (Followers: 1)
Central European Journal of Physics     Hybrid Journal   (Followers: 1)
CERN courier. International journal of high energy physics     Free  
Chinese Journal of Astronomy and Astrophysics     Full-text available via subscription   (Followers: 1)
Chinese Physics B     Full-text available via subscription  
Chinese Physics C     Full-text available via subscription  
Chinese Physics Letters     Full-text available via subscription  
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Colloid Journal     Hybrid Journal   (Followers: 2)
Communications in Mathematical Physics     Hybrid Journal   (Followers: 2)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 3)
Communications in Theoretical Physics     Full-text available via subscription   (Followers: 1)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 50)
Composites Part B : Engineering     Hybrid Journal   (Followers: 68)
Computational Materials Science     Hybrid Journal   (Followers: 19)
Computational Mathematics and Mathematical Physics     Hybrid Journal   (Followers: 1)
Computational Particle Mechanics     Hybrid Journal  
Computational Science and Discovery     Full-text available via subscription  
Computer Physics Communications     Hybrid Journal  
Contemporary Concepts of Condensed Matter Science     Full-text available via subscription  
Contemporary Physics     Hybrid Journal   (Followers: 10)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 3)
Contributions to Plasma Physics     Hybrid Journal   (Followers: 2)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 1)
Cryogenics     Hybrid Journal   (Followers: 14)
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Differential Equations and Nonlinear Mechanics     Open Access   (Followers: 4)
Doklady Physics     Hybrid Journal   (Followers: 1)
Dynamical Properties of Solids     Full-text available via subscription  

        1 2 3 4 5 6 | Last

Journal Cover Advances in Condensed Matter Physics
   [8 followers]  Follow    
  This is an Open Access Journal Open Access journal
     ISSN (Print) 1687-8108 - ISSN (Online) 1687-8124
     Published by Hindawi Publishing Corporation Homepage  [366 journals]   [SJR: 0.6]   [H-I: 7]
  • Is There a Metamaterial Route to High Temperature Superconductivity?

    • Abstract: Superconducting properties of a material such as electron-electron interactions and the critical temperature of superconducting transition can be expressed via the effective dielectric response function () of the material. Such a description is valid on the spatial scales below the superconducting coherence length (the size of the Cooper pair), which equals ∼100 nm in a typical BCS superconductor. Searching for natural materials exhibiting larger electron-electron interactions constitutes a traditional approach to high temperature superconductivity research. Here we point out that recently developed field of electromagnetic metamaterials deals with somewhat related task of dielectric response engineering on sub-100 nm scale. We argue that the metamaterial approach to dielectric response engineering may considerably increase the critical temperature of a composite superconductor-dielectric metamaterial.
      PubDate: Thu, 04 Dec 2014 00:10:10 +000
       
  • Numerical Study of Membrane Configurations

    • Abstract: We studied biological membranes of spherical topology within the framework of the spontaneous curvature model. Both Monte Carlo simulations and the numerical minimization of the curvature energy were used to obtain the shapes of the vesicles. The shapes of the vesicles and their energy were calculated for different values of the reduced volume. The vesicles which exhibit in-plane ordering were also studied. Minimal models have been developed in order to study the orientational ordering in colloids coated with a thin sheet of nematic liquid crystal (nematic shells). The topological defects are always present on the surfaces with the topology of a sphere. The location of the topological defects depends strongly on the curvature of the surface. We studied the nematic ordering and the formation of topological defects on vesicles obtained by the minimization of the spontaneous curvature energy.
      PubDate: Sun, 30 Nov 2014 00:10:21 +000
       
  • Field Induced Memory Effects in Random Nematics

    • Abstract: We studied numerically external field induced memory effects in randomly perturbed nematic liquid crystals. Random anisotropy nematic-type lattice model was used. The impurities imposing orientational disorder were randomly spatially distributed with the concentration below the percolation threshold. Simulations were carried for finite temperatures, where we varied , interaction strength between LC molecules, and impurities and external field . In the plane we determined lines separating short range—quasi long range and quasi long range—long range order. Furthermore, crossover regime separating external field and random field dominated regime was estimated. We calculated remanent nematic ordering in samples at as a function of the previously experienced external field strength .
      PubDate: Sun, 30 Nov 2014 00:10:19 +000
       
  • Investigations on Growth, Optical and Thermal Properties of Sulphamic Acid
           Single Crystals

    • Abstract: Single crystals of sulphamic acid of 11 × 7 × 3 mm3 dimension were successfully grown by slow evaporation technique. The crystal structure of grown crystals was confirmed by single crystal X-ray diffraction analysis. The presence of functional groups in the crystal lattice has been qualitatively determined by FT-IR and FT-Raman analyses. Theoretical group factor analysis predicts the possible modes of vibrations. The optical transmission spectroscopy (UV-Vis) clearly evidences the suitability of this material for optical application. The thermal behaviour of the crystal was studied by thermogravimetric (TG) and differential scanning calorimetric (DSC) studies. The nonlinear optical (NLO) characteristic of this material was explored by the second harmonic generation (SHG) conversion efficiency.
      PubDate: Tue, 25 Nov 2014 00:00:00 +000
       
  • Investigation of Structural, Magnetic, and Optical Properties of ZnO
           Codoped with Co and Cd

    • Abstract: Co and Cd have been codoped in ZnO using a simple solid state reaction technique to synthesize dilute magnetic oxide semiconductors of composition Zn0.9Co0.1−xCdxO ( with an increment of 0.02). Hexagonal wurtzite structure has been obtained for samples up to , using X-ray diffractometry. However, at and 0.1, secondary peak of CdO is observed. Raman spectra of the samples have been obtained in 200–800 cm−1 range. UV-VIS spectrophotometer is used to study the optical properties, which shows that band gap energy decreases with the increase in Cd concentration. A weak ferromagnetic behavior was evident which decreased further by adding Cd in the series. Room temperature resistivity measurements performed using four-point probe technique showed that their values lie in the semiconductor range. Structural morphology of the samples has been investigated by a scanning electron microscope and grain size has been determined. Raman spectra and Fourier transform infrared spectroscopy revealed the successful incorporation of Co and Cd ions into the host ZnO lattice.
      PubDate: Mon, 24 Nov 2014 06:32:12 +000
       
  • The Gap and the Upper Critical Field as Function of Doping for High-
           Cuprates

    • Abstract: The relation between the -wave superconducting gap and the specific heat obtained with the Volovik effect is used to determine the upper critical field as doping function, for high-temperature superconductors. A two-components model with -wave symmetry, within the BCS framework, is introduced to describe the superconducting state. Generalized Fermi surface topologies are used in order to increase the density of states at the Fermi level, allowing the high- values observed. The electron-phonon interaction is considered the most relevant mechanism for the high- cuprates, where the available phonon energy is provided by the half-breathing modes. The energy gap values calculated with this model are introduced to describe the variation of the upper critical field as function of doping, for .
      PubDate: Mon, 24 Nov 2014 00:00:00 +000
       
  • Composite Operator Method Analysis of the Underdoped Cuprates Puzzle

    • Abstract: The microscopical analysis of the unconventional and puzzling physics of the underdoped cuprates, as carried out lately by means of the composite operator method (COM) applied to the 2D Hubbard model, is reviewed and systematized. The 2D Hubbard model has been adopted as it has been considered the minimal model capable of describing the most peculiar features of cuprates held responsible for their anomalous behavior. COM is designed to endorse, since its foundation, the systematic emergence in any SCS of new elementary excitations described by composite operators obeying noncanonical algebras. In this case (underdoped cuprates—2D Hubbard model), the residual interactions—beyond a 2-pole approximation—between the new elementary electronic excitations, dictated by the strong local Coulomb repulsion and well described by the two Hubbard composite operators, have been treated within the noncrossing approximation. Given this recipe and exploiting the few unknowns to enforce the Pauli principle content in the solution, it is possible to qualitatively describe some of the anomalous features of high-Tc cuprate superconductors such as large versus small Fermi surface dichotomy, Fermi surface deconstruction (appearance of Fermi arcs), nodal versus antinodal physics, pseudogap(s), and kinks in the electronic dispersion. The resulting scenario envisages a smooth crossover between an ordinary weakly interacting metal sustaining weak, short-range antiferromagnetic correlations in the overdoped regime to an unconventional poor metal characterized by very strong, long-but-finite-range antiferromagnetic correlations leading to momentum-selective non-Fermi liquid features as well as to the opening of a pseudogap and to the striking differences between the nodal and the antinodal dynamics in the underdoped regime.
      PubDate: Mon, 10 Nov 2014 12:29:05 +000
       
  • Atomistic Simulation of Intrinsic Defects and Trivalent and Tetravalent
           Ion Doping in Hydroxyapatite

    • Abstract: Atomistic simulation techniques have been employed in order to investigate key issues related to intrinsic defects and a variety of dopants from trivalent and tetravalent ions. The most favorable intrinsic defect is determined to be a scheme involving calcium and hydroxyl vacancies. It is found that trivalent ions have an energetic preference for the Ca site, while tetravalent ions can enter P sites. Charge compensation is predicted to occur basically via three schemes. In general, the charge compensation via the formation of calcium vacancies is more favorable. Trivalent dopant ions are more stable than tetravalent dopants.
      PubDate: Sun, 12 Oct 2014 12:12:08 +000
       
  • The Origin and Coupling Mechanism of the Magnetoelectric Effect in
           TMCl2-4SC(NH2)2 (TM = Ni and Co)

    • Abstract: Most research on multiferroics and magnetoelectric effects to date has focused on inorganic oxides. Molecule-based materials are a relatively new field in which to search for magnetoelectric multiferroics and to explore new coupling mechanisms between electric and magnetic order. We present magnetoelectric behavior in NiCl2-4SC(NH2)2 (DTN) and CoCl2-4SC(NH2)2 (DTC). These compounds form tetragonal structures where the transition metal ion (Ni or Co) is surrounded by four electrically polar thiourea molecules [SC(NH2)2]. By tracking the magnetic and electric properties of these compounds as a function of magnetic field, we gain insights into the coupling mechanism by observing that, in DTN, the electric polarization tracks the magnetic ordering, whereas in DTC it does not. For DTN, all electrically polar thiourea molecules tilt in the same direction along the c-axis, breaking spatial-inversion symmetry, whereas, for DTC, two thiourea molecules tilt up and two tilt down with respect to c-axis, perfectly canceling the net electrical polarization. Thus, the magnetoelectric coupling mechanism in DTN is likely a magnetostrictive adjustment of the thiourea molecule orientation in response to magnetic order.
      PubDate: Mon, 08 Sep 2014 00:00:00 +000
       
  • Spatially Resolved Cathodoluminescence in the Vicinity of Defects in the
           High-Efficiency InGaN/GaN Blue Light Emitting Diodes

    • Abstract: In addition to the standard 447 nm blue emission from the InGaN/GaN multiple quantum wells, a high-energy shoulder is clearly observed in cathodoluminescence spectra of the high-efficiency InGaN/GaN blue light emitting diodes grown on sapphire substrates by metalorganic chemical vapor deposition. Monochromatic cathodoluminescence images of the samples measured at low temperature reveal a competition between the two emissions in the vicinity of the dislocations. The high-energy emission is dominant at the regions near the dislocation cores, while the blue emission is enhanced around the dislocation edges. The high-energy emission region is considered as a potential barrier that prevents the carriers for the blue emission from nonradiatively recombining at the dislocations.
      PubDate: Mon, 01 Sep 2014 07:47:49 +000
       
  • Influence of Codoping on the Optical Properties of ZnO Thin Films
           Synthesized on Glass Substrate by Chemical Bath Deposition Method

    • Abstract: Fe and K simultaneously doped ZnO thin films Zn0.99 K0.01 (Fe)x O (, 2, 3, and 4%) were synthesized by chemical bath deposition method. The XRD investigation reveals that all the doped ZnO thin films are in hexagonal wurtzite crystal structure without impurity phases. With increase in Fe concentration, the growth of thin films along c axis is evident from the XRD which indicates the increase in intensity along (002) direction. The same is visible from the surface morphology which shows the formation of hexagonal structure for higher Fe concentration. The topography shows gradual variation with Fe incorporation. The optical energy band gap obtained from the transmittance spectrum decreases from 3.42 to 3.06 eV with increase in Fe concentration indicating the red shift and this trend is consistent with the earlier experimental results. The UV emission is centered around 3.59 eV. The optical constants such as refractive index, extinction coefficient, and absorption coefficient which are essential for the optoelectronic applications were also determined.
      PubDate: Sun, 31 Aug 2014 12:07:12 +000
       
  • Structural, Electronic, and Optical Properties of Functional Metal Oxides

    • PubDate: Sun, 31 Aug 2014 08:52:34 +000
       
  • The Low Temperature Specific Heat of Pr0.65Ca0.35MnO3

    • Abstract: The low temperature specific heat of polycrystalline perovskite-type Pr0.65Ca0.35MnO3 manganese oxide has been investigated experimentally. It is found that the low temperature electron specific heat in zero magnetic field is obviously larger than that of ordinary rare-earth manganites oxide. To get the contribution of phonon to the specific heat precisely, the lattice specific heat is calculated by Debye model fitting. Results confirm that the low temperature specific heat of Pr0.65Ca0.35MnO3 is related to the itinerant electrons in ferromagnetic clusters and the disorder in the sample.
      PubDate: Mon, 25 Aug 2014 08:05:05 +000
       
  • Laser-Induced Point Defects in Fused Silica Irradiated by UV Laser in
           Vacuum

    • Abstract: High-purity fused silica irradiated by third harmonic of the Nd:YAG laser in vacuum with different laser pulse parameters was studied experimentally. Laser-induced defects are investigated by UV spectroscopy, and fluorescence spectra and correlated to the structural modifications in the glass matrix through Raman spectroscopy. Results show that, for laser fluence below laser-induced damage threshold (LIDT), the absorbance and intensity of fluorescence bands increase with laser energies and/or number of laser pulses, which indicates that laser-induced defects are enhanced by laser energies and/or number of laser pulses in vacuum. The optical properties of these point defects were discussed in detail.
      PubDate: Sun, 17 Aug 2014 12:27:55 +000
       
  • Cracking Tendency Prediction of High-Performance Cementitious Materials

    • Abstract: The constraint ring test is widely used to assess the cracking potential for early-age cementitious materials. In this paper, the analytical expressions based on elastic mechanism are presented to estimate the residual stresses of the restrained mortar ring by considering the comprehensive effects of hydration heat, autogenous and drying shrinkage, creeping, and restraint. In the present analytical method, the stress field of the restrained ring is treated as the superposition of those caused by hydration heat, external restraint, autogenous and drying shrinkage, and creep. The factors including the properties of materials, environmental parameters such as relative humidity and temperature, the geometry effect of specimen, and the relative constraint effects of steel ring to mortar ring, are taken into account to predict the strain development with age of mortar. The temperature of the ring, the elastic modulus, the creep strain, and the split tensile strength are measured to validate the model. The age of cracking is predicted by comparing the estimated maximum tensile stress of the restrained mortar ring with the measured split tensile strength of specimen. The suitability of the present analytical method is assessed by comparing with the restraint ring test and a soundly good agreement is observed.
      PubDate: Tue, 05 Aug 2014 09:50:29 +000
       
  • Dynamics and Matter-Wave Solitons in Bose-Einstein Condensates with Two-
           and Three-Body Interactions

    • Abstract: By means of similarity transformation, this paper proposes the matter-wave soliton solutions and dynamics of the variable coefficient cubic-quintic nonlinear Schrödinger equation arising from Bose-Einstein condensates with time-dependent two- and three-body interactions. It is found that, under the effect of time-dependent two- and three-body interaction and harmonic potential with time-dependent frequency, the density of atom condensates will gradually diminish and finally collapse.
      PubDate: Tue, 05 Aug 2014 08:15:41 +000
       
  • First Principles Study of Cerium Monochalcogenides

    • Abstract: A theoretical investigation of structural, magnetic, electronic, and lattice dynamical properties of cerium monochalcogenides using the generalized gradient approximation (GGA) + U within ultrasoft pseudopotentials and a plane-wave basis is presented. All the calculated quantities, except the local magnetic moments, are found to be in good agreement with the experimental data. The lattice dynamical results indicate a strong chalcogenide dependence for the anomalous features of the phonon dispersions.
      PubDate: Mon, 21 Jul 2014 09:40:30 +000
       
  • Full Aperture CO2 Laser Process to Improve Laser Damage Resistance of
           Fused Silica Optical Surface

    • Abstract: An improved method is presented to scan the full-aperture optical surface rapidly by using galvanometer steering mirrors. In contrast to the previous studies, the scanning velocity is faster by several orders of magnitude. The velocity is chosen to allow little thermodeposition thus providing small and uniform residual stress. An appropriate power density is set to obtain a lower processing temperature. The proper parameters can help to prevent optical surface from fracturing during operation at high laser flux. S-on-1 damage test results show that the damage threshold of scanned area is approximately 40% higher than that of untreated area.
      PubDate: Thu, 17 Jul 2014 00:00:00 +000
       
  • Laser-Induced Damage Initiation and Growth of Optical Materials

    • Abstract: The lifetime of optical components is determined by the combination of laser-induced damage initiation probability and damage propagation rate during subsequent laser shots. This paper reviews both theoretical and experimental investigations on laser-induced damage initiation and growth at the surface of optics. The damage mechanism is generally considered as thermal absorption and electron avalanche, which play dominant roles for the different laser pulse durations. The typical damage morphology in the surface of components observed in experiments is also closely related to the damage mechanism. The damage crater in thermal absorption process, which can be estimated by thermal diffusion model, is typical distortion, melting, and ablation debris often with an elevated rim caused by melted material flow and resolidification. However, damage initiated by electron avalanche is often accompanied by generation of plasma, crush, and fracture, which can be explained by thermal explosion model. Damage growth at rear surface of components is extremely severe which can be explained by several models, such as fireball growth, impact crater, brittle fracture, and electric field enhancement. All the physical effects are not independent but mutually coupling. Developing theoretical models of multiphysics coupling are an important trend for future theoretical research. Meanwhile, more attention should be paid to integrated analysis both in theory and experiment.
      PubDate: Wed, 16 Jul 2014 10:26:02 +000
       
  • Electrical and Dielectric Characterization of Bi12GeO20 Prepared by
           Modified Pechini Method

    • Abstract: Bismuth germanate () ceramics were produced using modified Pechini route, and the synthesis parameters, crystalline phases, microstructure, and sintering conditions were investigated. powders with submicrometric particle sizes were investigated for calcination temperatures from 400 to 600°C, with soaking times of 1 h and 5 h. Controlling the synthesis parameters, dense ceramics with two different grain sizes of 3.4 ± 0.5 µm and 5.7 ± 0.8 µm could be produced after sintering at 750°C/1 h. The electric and dielectric properties of these ceramics were determined by impedance spectroscopy (IS). From the results, it was concluded that the dielectric permittivity measured at high frequencies is insensitive to the grain size, while the AC dark conductivity presents a noticeable dependency on this feature. This behaviour was discussed on the basis of a Maxwell-Wagner interfacial relaxation, whose intensity depends directly on the volume fraction of grain boundaries in the sample.
      PubDate: Tue, 15 Jul 2014 10:15:27 +000
       
  • Study on Macroscopic and Microscopic Mechanical Behavior of
           Magnetorheological Elastomers by Representative Volume Element Approach

    • Abstract: By using a representative volume element (RVE) approach, this paper investigates the effective mechanical properties of anisotropic magnetorheological elastomers (MREs) in which particles are aligned and form chain-like structure under magnetic field during curing. Firstly, a three-dimensional RVE in zero magnetic field is presented in ABAQUS/Standard to calculate the macroscopic mechanical properties of MREs. It is shown that the initial shear modulus of MREs increases by 56% with a 20% volume fraction of particles compared to that of pure rubber. Then by introducing the Maxwell stress tensor, a two-dimensional plane stress RVE for the MRE is developed in COMSOL Multiphysics to study its response under a magnetic field. The influences of magnetic field intensity, radius of particles, and distance between two adjacent particles on the macroscopic mechanical properties of MRE are also investigated. The results show that the shear modulus increases with the increase of the applied magnetic field intensity and the radius of particles and the decrease of the distance between two adjacent particles in a chain. The predicted numerical results are consistent with theoretical results from Mori-Tanaka model, double inclusion model, and dipole model.
      PubDate: Thu, 10 Jul 2014 07:04:32 +000
       
  • Effect of Concurrent ZnO Addition and AlF3 Reduction on the Elastic
           Properties of Tellurite Based Glass System

    • Abstract: New ternary zinc oxyfluorotellurite (ZOFT) with the composition --, where ; ; , has been successfully prepared by the conventional rapid melt quenching technique. Density, molar volume, and glass transition temperature have been assessed for each ZOFT glass sample. The longitudinal and transverse ultrasonic waves propagated in each glass sample were measured using a MBS8020 ultrasonic data acquisition system at 5 MHz frequency and room temperature. The longitudinal modulus (), shear modulus (), Young’s modulus (), bulk modulus (), and Poisson’s ratio () are assessed from both velocity data and their respective density. The compositional dependence of the ultrasonic velocities and related parameters are discussed to understand the rigidity and compactness of the glass system studied.
      PubDate: Tue, 08 Jul 2014 12:03:26 +000
       
  • Advanced Catalysis and Nanostructure Design for Solar Energy Conversion

    • PubDate: Mon, 07 Jul 2014 07:49:41 +000
       
  • A Contamination Sensor Based on an Array of Microfibers with
           Nanoscale-Structured Film

    • Abstract: A contamination sensor based on an array of microfibers with nanoscale-structured film using evanescent field is proposed and demonstrated theoretically and experimentally. When the molecular contaminants deposit on the nanoscale-structured film, the refractive index of the film will change and the additional loss will be produced due to the disturbance of evanescent field. The possibility of the sensor is demonstrated theoretically by using three-dimensional finite-difference time domain (3D-FDTD). The corresponding experiments have also been carried out in order to demonstrate the theoretical results. Microfibers are fabricated by using hydrogen-oxygen flame-heated scanning fiber drawing method and the nanoscale-structured film coated on the surface of microfibers is deposited by using dip coating process. Then an array of microfibers is assembled to demonstrate the feasibility of the device. The experimental results show that contaminants detection with the device can agree well with the results measured by the laser-scattering particle counter, which demonstrates the feasibility of the new type of contaminant sensor. The device can be used to monitor contaminants on-line in the high-power laser system.
      PubDate: Tue, 01 Jul 2014 07:51:26 +000
       
  • Surface Contaminant Control Technologies to Improve Laser Damage
           Resistance of Optics

    • Abstract: The large high-power solid lasers, such as the National Ignition Facility (NIF) of America and the Shenguang-III (SG-III) laser facility of China, can output over 2.1 MJ laser pulse for the inertial confinement fusion (ICF) experiments. Because of the enhancement of operating flux and the expansion of laser driver scale, the problem of contamination seriously influences their construction period and operation life. During irradiation by intense laser beams, the contaminants on the metallic surface of beam tubes can be transmitted to the optical surfaces and lead to damage of optical components. For the high-power solid-state laser facilities, contamination control focuses on the slab amplifiers, spatial filters, and final-optical assemblies. In this paper, an effective solution to control contaminations including the whole process of the laser driver is put forward to provide the safe operation of laser facilities, and the detailed technical methods of contamination control such as washing, cleanliness metrology, and cleanliness protecting are also introduced to reduce the probability of laser-induced damage of optics. The experimental results show that the cleanliness level of SG-III laser facility is much better to ensure that the laser facility can safely operate at high energy flux.
      PubDate: Sun, 29 Jun 2014 11:41:07 +000
       
  • One-Dimensional Nonequilibrium Radiation-Transport Equation under
           Diffusion Approximation and Its Discrete Scheme

    • Abstract: Based on the nonlocal thermodynamic equilibrium state and large optical thickness of plasma, we establish one-dimensional nonequilibrium radiation-transport equation from diffusion approximation. Through finite volume method, the discrete scheme of radiation-transport equation and the conditions for its definite solution are proposed. The reliability of radiation-transport equation and its discrete scheme is validated.
      PubDate: Tue, 24 Jun 2014 12:16:03 +000
       
  • Evolution of Helium with Temperature in Neutron-Irradiated 10B-Doped
           Aluminum by Small-Angle X-Ray Scattering

    • Abstract: Helium status is the primary effect of material properties under radiation. 10B-doped aluminum samples were prepared via arc melting technique and rapidly cooled with liquid nitrogen to increase the boron concentration during the formation of compounds. An accumulated helium concentration of ~6.2 × 1025 m−3 was obtained via reactor neutron irradiation with the reaction of 10B(n, α)7Li. Temperature-stimulated helium evolution was observed via small-angle X-ray scattering (SAXS) and was confirmed via transmission electron microscopy (TEM). The SAXS results show that the volume fraction of helium bubbles significantly increased with temperature. The amount of helium bubbles reached its maximum at 600°C, and the most probable diameter of the helium bubbles increased with temperature until 14.6 nm at 700°C. A similar size distribution of helium bubbles was obtained via TEM after in situ SAXS measurement at 700°C, except that the most probable diameter was 3.9 nm smaller.
      PubDate: Sun, 22 Jun 2014 13:41:02 +000
       
  • Influence of Ambient Temperature on Nanosecond and Picosecond
           Laser-Induced Bulk Damage of Fused Silica

    • Abstract: The nanosecond (ns) and picosecond (ps) pulsed laser-induced damage behaviors of fused silica under cryogenic and room temperature have been investigated. The laser-induced damage threshold (LIDT) and damage probability are used to understand the damage behavior at different ambient temperatures. The results show that the LIDTs for both ns and ps slightly increased at cryogenic temperature compared to that at room temperature. Meanwhile, the damage probability has an inverse trend; that is, the damage probability at low temperature is smaller than that at room temperature. A theoretical model based on heated crystal lattice is well consistent with the experimental results.
      PubDate: Thu, 19 Jun 2014 12:04:47 +000
       
  • Effect of UV Laser Conditioning on the Structure of KDP Crystal

    • Abstract: Multiparametric raster scanning experiments for KDP crystals are carried out to study the laser conditioning efficiency as a function of laser fluence, fluence step, and pulse sequence by using ultraviolet (UV) laser irradiation with pulse duration of approximately 7 ns. It indicates that damage resistance of KDP can be enhanced after conditioning process. And laser conditioning efficiency depends on the maximal fluence which is below the damage threshold. Raman spectra and photothermal absorption have also been studied on KDP crystals before and after multiparametric laser conditioning. Photothermal absorption data reveal that absorbance of conditioned KDP crystal decreases with the increase of laser fluence and the damage threshold of low absorption area is higher. Raman analysis reveals that the effectiveness of laser conditioning relies mainly on the individual mode of PO4 molecule.
      PubDate: Wed, 18 Jun 2014 07:15:47 +000
       
  • Effect of Heating Method on Hydrogen Production by Biomass Gasification in
           Supercritical Water

    • Abstract: The glucose as a test sample of biomass is gasified in supercritical water with different heating methods driven by renewable solar energy. The performance comparisons of hydrogen production of glucose gasification are investigated. The relations between temperature raising speed of reactant fluid, variation of volume fraction, combustion enthalpy, and chemical exergy of H2 of the product gases with reactant solution concentration are presented, respectively. The results show that the energy quality of product gases with preheating process is higher than that with no preheating unit for hydrogen production. Hydrogen production quantity and gasification rate of glucose decrease obviously with the increase of concentration of material in no preheating system.
      PubDate: Tue, 17 Jun 2014 09:09:43 +000
       
 
 
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