Modeling of Polarization-Specific Phonon Transmission Through Interfaces

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
Zhen Huang ◽  
Jayathi Y. Murthy ◽  
Timothy S. Fisher
Keyword(s):  
Density Of States ◽  
Function Method ◽  
Bulk Material ◽  
Transmission Function ◽  
Dissimilar Materials ◽  
Bulk Materials ◽  
Phonon Branch ◽  
Self Energy ◽  
Frequency Independent ◽  
Eigenvectors And Eigenvalues

In this work, the atomistic Green’s function method is extended to compute transmission functions for each phonon polarization. The eigenvectors and eigenvalues of the overall density of states matrices are manipulated to yield a density of states matrix for each polarization. A decomposed self-energy is calculated from the density of states matrix for each polarization and used to calculate the transmission function for a particular phonon branch. In a pure bulk material such as silicon, each transmission function exhibits a frequency-independent value of unity. In heterogeneous bulk materials, the transmission function is reduced significantly due to the junction of dissimilar materials.

Modeling of Polarization-Specific Phonon Transmission Functions Through Interfaces

2008 ◽  
Author(s):  
Zhen Huang ◽  
Jayathi Murthy ◽  
Timothy Fisher
Keyword(s):  
Theoretical Prediction ◽  
Density Of States ◽  
Bulk Material ◽  
Transmission Function ◽  
Dissimilar Materials ◽  
Bulk Materials ◽  
Phonon Branch ◽  
Self Energy ◽  
Frequency Independent ◽  
Eigenvectors And Eigenvalues

The atomistic Green’s function (AGF) method has been used successfully in previous research to predict the transmission function for energy carriers at interfaces. In this work, the method is extended to capture the transmission function for each phonon polarization. The inputs for this extension are the same as for the original AGF method. Furthermore, this method does not require any complex manipulation of harmonic matrices and can be applied to different materials and geometries. The eigenvectors and eigenvalues of the overall density of states matrices are manipulated to yield the density of states matrix for each polarization. A decomposed self-energy is calculated from the density of states matrix for each polarization and used to calculate the transmission function for a particular phonon branch. In a pure bulk material such as silicon, each transmission function exhibits a frequency-independent value of unity, which matches the theoretical prediction. In heterogeneous bulk materials, the transmission function is reduced significantly due to the contact of dissimilar materials. The summation of the decomposed transmission functions is shown to reproduce the result from a direct AGF calculation in which all branches were treated together.

Influence of temperature and humidity on the angle of repose of wood bulk materials

2016 ◽  
Author(s):  
И.В. Бачериков ◽  
Б.М. Локштанов
Keyword(s):  
Field Experiments ◽  
Bulk Material ◽  
Average Particle Size ◽  
Operating Conditions ◽  
Angle Of Repose ◽  
Wood Dust ◽  
Average Particle ◽  
Bulk Materials ◽  
Technical Literature ◽  
The Impact

При проектировании открытых и закрытых хранилищ измельченных сыпучих материалов древесных материалов, таких как щепа и опилки, большое значение имеет угол естественного откоса (статический и динамический) этих материалов. В технической литературе приводятся противоречивые сведения о величине этих углов, что приводит к ошибкам при проектировании складов. В справочных данных не учитываются условия, в которых эксплуатируются емкости для хранения сыпучих материалов, свойства и состояние этих сыпучих материалов. В свою очередь, ошибки при проектировании приводят к проблемам (зависание, сводообразование, «затопление» и т. д.) и авариям при эксплуатации бункеров и силосов на производстве. В статье представлены сведения, посвященные влиянию влажности и температуры на угол естественного откоса сыпучих материалов. На основании лабораторных и натурных экспериментов, проведенных с помощью специально разработанных методик и установок, была скорректирована формула для определения углов естественного откоса (статического и динамического) для измельченных древесных материалов в зависимости от их фракционного и породного состава, влажности (абсолютной и относительной) и температуры. При помощи скорректированной формулы можно определить угол естественного откоса древесных сыпучих материалов со среднегеометрическим размером частицы от 0,5 мм до 15 мм (от древесной пыли до технологической щепы) в различных производственных условиях. Статья может быть полезна проектировщикам при расчете угла наклона граней выпускающей воронки бункеров и силосов предприятий лесной отрасли и целлюлозо-бумажной промышленности. In the design of open and closed storage warehouses chopped wood materials for bulk materials such as wood chips and sawdust, great importance has an angle of repose (static and dynamic) of these materials. In the technical literature are conflicting reports about the magnitude of these angles, which leads to errors in the design of warehouses. In the referencesdoes not take into account the conditions under which operated capacities for storage of bulk materials, and properties and condition of the bulk material. The design errors lead to problems (hanging, arching, «flooding», etc.) and accidents in the operation of hoppers and silos at the mills. The article provides information on the impact of humidity and temperature on the angle of repose of granular materials. On the basis of laboratory and field experiments, conducted with the help of specially developed techniques and facilities has been adjusted formula for determining the angle of repose (static and dynamic) for the shredded wood materials depending on their fractional and species composition, humidity (absolute and relative) and temperature. It is possible, by using the corrected formula, to determine the angle of repose of loose wood materials with average particle size of from 0.5 mm to 15 mm (wood dust to pulpchips) in various operating conditions. The article can be helpful to designers in the calculation of the angle of inclination of the funnel faces produces bunkers and silos forest industries and pulp and paper industry.

scholarly journals Vibrational Spectroscopy of Boron Nitride at High Temperatures and Pressures

1989 ◽  
Vol 162 ◽  
Author(s):  
Gregory Y. Exarhos ◽  
Nancy J. Hess
Keyword(s):  
Boron Nitride ◽  
Bulk Material ◽  
Hexagonal Phase ◽  
Bulk Materials ◽  
Lattice Thermal Expansion ◽  
Line Frequency ◽  
Nitride Coatings ◽  
Scattering Measurements ◽  
Sputter Deposited ◽  
Inherent Strain

ABSTRACTRaman scattering measurements are used to distinguish between amorphous and crystalline phases in sputter deposited boron nitride coatings and bulk materials. Changes in vibrational line frequency and linewidth can be attributed to differences in particle size or inherent strain which can be quantified from pressure-dependent measurements of the bulk material. The response of the Raman-allowed E2g modes (hexagonal phase) to temperature is described by a forced dampeg harmonic oscillator model from which the intra- and interplanar lattice thermal expansion can be estimated.

Structures and magnetic properties of Sm-Fe-N bulk magnets produced by the spark plasma sintering method

2007 ◽  
Vol 22 (11) ◽  
pp. 3130-3136 ◽  
Author(s):  
Tetsuji Saito
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Bulk Material ◽  
Decomposition Temperature ◽  
High Coercivity ◽  
Bulk Materials ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method ◽  
N Powder

Sm-Fe-N powders were successfully consolidated at 873 K and below by the spark plasma sintering (SPS) method. Although the decomposition temperature of the hard magnetic Sm2Fe17N3 phase has been reported to be 873 K, partial decomposition of the Sm2Fe17N3 phase was noted in the bulk materials obtained by sintering at below that temperature. The resultant bulk materials showed a coercivity of around 0.24 MAm−1, significantly lower than that of the original Sm-Fe-N powder. It was found that decomposition of the Sm2Fe17N3 phase in the SPS method was significantly lowered by the addition of a small amount of Zn powder to the Sm-Fe-N powder. The bulk material obtained by sintering a mixture of Sm-Fe-N and Zn powder (10%Zn) at 723 K exhibited high coercivity, comparable with that of the original Sm-Fe-N powder.

scholarly journals Programming function into mechanical forms by directed assembly of silk bulk materials

2016 ◽  
Vol 114 (3) ◽  
pp. 451-456 ◽  
Author(s):  
Benedetto Marelli ◽  
Nereus Patel ◽  
Thomas Duggan ◽  
Giovanni Perotto ◽  
Elijah Shirman ◽  
...  
Keyword(s):  
Self Assembly ◽  
Biological Function ◽  
Bulk Material ◽  
Directed Assembly ◽  
Water Soluble ◽  
Infrared Light ◽  
Bulk Materials ◽  
Protein Matrix ◽  
On Demand ◽  
Water Based

We report simple, water-based fabrication methods based on protein self-assembly to generate 3D silk fibroin bulk materials that can be easily hybridized with water-soluble molecules to obtain multiple solid formats with predesigned functions. Controlling self-assembly leads to robust, machinable formats that exhibit thermoplastic behavior consenting material reshaping at the nanoscale, microscale, and macroscale. We illustrate the versatility of the approach by realizing demonstrator devices where large silk monoliths can be generated, polished, and reshaped into functional mechanical components that can be nanopatterned, embed optical function, heated on demand in response to infrared light, or can visualize mechanical failure through colorimetric chemistries embedded in the assembled (bulk) protein matrix. Finally, we show an enzyme-loaded solid mechanical part, illustrating the ability to incorporate biological function within the bulk material with possible utility for sustained release in robust, programmably shapeable mechanical formats.

Simulation of Phonon Transmission at Semiconductor Interfaces Using an Atomistic Green’s Function Method

2008 ◽  
Author(s):  
Lin Sun ◽  
Jayathi Y. Murthy ◽  
Zhen Huang
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Function Method ◽  
Local Density ◽  
Cutoff Frequency ◽  
Transmission Function ◽  
Phonon Transport ◽  
Atomic Scale ◽  
Rough Interface ◽  
Green’S Function Method

An atomistic Green’s function method is applied to study phonon transport across interfaces between two semi-infinite semiconductors. We investigate the dependence of phonon transmission function on interface atomic configuration, roughness layer thickness and phonon frequency. The transmission function is obtained for a number of interface configurations, including Si/Ge/Si confined structures and a single Si/Ge interface. An interface with a regularly-patterned roughness is investigated to illustrate how the rough interface influences phonon transmission. The results show that the cutoff frequency and the local density of states are modified due to the rough interface. The transmission function is found to strongly dependent on the presence of atomic-scale roughness.

scholarly journals Renovation of Interest in the Magnetoelectric Effect in Nanoferroics

2018 ◽  
Vol 63 (11) ◽  
pp. 1006 ◽  
Author(s):  
M. D. Glinchuk ◽  
V. V. Khist
Keyword(s):  
Size Effects ◽  
Magnetoelectric Effect ◽  
Bulk Material ◽  
Bismuth Ferrite ◽  
Phenomenological Theory ◽  
Magnetoelectric Coupling ◽  
Theoretical Studies ◽  
Coupling Coefficients ◽  
Bulk Materials ◽  
Magnetoelectric Properties

Recent theoretical studies of the influence of the magnetoelectric effect on the physical properties of nanosized ferroics and multiferroics have been reviewed. Special attention is focused on the description of piezomagnetic, piezoelectric, and linear magnetoelectric effects near the ferroid surface in the framework of the Landau–Ginzburg–Devonshire phenomenological theory, where they are considered to be a result of the spontaneous surface-induced symmetry reduction. Therefore, nanosized particles and thin films can manifest pronounced piezomagnetic, piezoelectric, and magnetoelectric properties, which are absent for the corresponding bulk materials. In particular, the giant magnetoelectric effect induced in nanowires by the surface tension is possible. A considerable influence of size effects and external fields on the magnetoelectric coupling coefficients and the dielectric, magnetic, and magnetoelectric susceptibilities in nanoferroics is analyzed. Particular attention is paid to the influence of a misfit deformation on the magnetoelectric coupling in thin ferroic films and their phase diagrams, including the appearance of new phases absent in the bulk material. In the framework of the Landau–Ginzburg–Devonshire theory, the linear magnetoelectric and flexomagnetoelectric effects induced in nanoferroics by the flexomagnetic coupling are considered, and a significant influence of the flexomagnetic effect on the nanoferroic susceptibility is marked. The manifestations of size effects in the polarization and magnetoelectric properties of semiellipsoidal bismuth ferrite nanoparticles are discussed.

scholarly journals ANALYTICAL DESCRIPTION OF THE MIXER PERFORMANCE FOR BULK MATERIALS WITH SCREW BLADES

2019 ◽  
pp. 69-78 ◽  
Author(s):  
Марина Борисова ◽  
Marina Borisova ◽  
Владимир Новиков ◽  
Vladimir Novikov ◽  
Владимир Коновалов ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Animal Feed ◽  
Bulk Material ◽  
Specific Energy Consumption ◽  
Analytical Description ◽  
Bulk Materials ◽  
Rotating Shaft ◽  
Discharge Opening ◽  
Horizontal Shaft ◽  
Blade Mixer

The aim of the study is to reduce the energy consumption of the blade mixer for bulk materials in regard to its de-sign parameters. Preparation of feed mixtures is carried out mainly by mixers of various designs, as well as extrud-ers and other auger equipment. Widespread horizontal mixers with blades mounted on a rotating shaft are wide-spread and used. They are distinguished by the ability to achieve the necessary smooth mixture within short oper-ating time. The main purpose of the proposed mixer is the preparation of dry mixtures of bulk feed components. The intended use of the mixer is the preparation of concentrated animal feed n agricultural production. In Samara SAA, the design of the blade mixer with screw blades was developed based on the literature review and analysis of the technological process of mixers. The mixer consists of a body with a horizontal shaft with radial trapezoidal screw blades. The proposed blades allow to direct forces in such a way that the total (resulting) projection of the resistant force of the material along the shaft will tend to zero due to the changing angle of the profile and width of the blades. At the same time, an axial force will be created at the edge of the blade at a certain radius, which facili-tates to unload mixer through the discharge opening. The expressions of specific energy consumption for mixing, as well as the work duration of the mixer cycle are given. An expression allowing estimation of an average flow rate of bulk material from the discharge opening of the mixer is obtained. It is established that the position of the gate regulating the area of the discharge opening can affect the volume of the portion simultaneously processed by the mixer, filling volume of mixer and the quality of the mixture.

scholarly journals TO THE SUBSTANTIATION OF THE STORAGE BUNKER DESIGN FOR A HIGH-ACCURACY VOLUMETRIC DOSING DEVICE

2020 ◽  
Vol 2 ◽  
pp. 173-179
Author(s):  
Guil Nam Khan ◽  
Evgeny P. Rusin
Keyword(s):  
Discrete Element Method ◽  
High Precision ◽  
Structural Design ◽  
Material Flow ◽  
Bulk Material ◽  
High Accuracy ◽  
Axially Symmetric ◽  
Bulk Materials ◽  
Main Components ◽  
Storage Hopper

The paper substantiates the design of one of the main components of a high-precision volumetric dosing device for bulk materials - its storage hopper. It is determined that hopper structural design should avoid possible hang-ups of the product processed and maintain rather uniform dense packing of the material on its way to the dosing area. The process of bulk material flow in a storage hopper was studied numerically by discrete element method. It is concluded that hopper design should be axially symmetric, with defect-free walls, and expanding at an angle of 2-4° to its base.

scholarly journals INVESTIGATION OF MEASUREMENT ACCURACY IN DETERMINING THE MASS OF BULK MATERIALS

2020 ◽  
Vol 8 (2) ◽  
pp. 42-48
Author(s):  
Galina V. Simonova
Keyword(s):  
Bulk Density ◽  
Fractional Composition ◽  
Bulk Material ◽  
Indirect Measurement ◽  
Bulk Materials ◽  
Technological Processes ◽  
Measurement Results ◽  
Accuracy Of Measurement ◽  
Fractional Control

The article is devoted to the assessment the error in determining the mass of a sample bulk materials when using the values of their bulk density. Precisely the accuracy of measurement results is necessary in many fields of activity to ensure the efficiency and safety of technological processes, as well as improving product quality. The relevance of this work is associated with the assessment of the inevitable deviations of the bulk density the same material in a given volume as a result of an uncontrolled fractional composition of a sample of bulk material. As a consequence of these deviations, an error arises in determining the mass of a sample of a given volume, even if this volume is an uniquely determined quantity. The paper presents the results of studies of the influence of the fractional composition of bulk materials on the determination of their mass in the indirect measurement method. A significant effect of the fractional composition of bulk materials on the error of the indirect method for determining the mass of the sample was revealed. It is shown, that there is a need for fractional control of the composition of bulk materials in the development of control operations of technological processes, as well as restrictions on the use of bulk density with increased requirements for the accuracy of determining the mass of a sample.

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