Comparison of ring bending strain with infrared bending vibrations

1969 ◽  
Vol 22 (12) ◽  
pp. 2575
Author(s):  
IJ Miller
Keyword(s):  
Force Constant ◽  
Empirical Formula ◽  
Reasonable Agreement ◽  
Bending Vibrations ◽  
Bending Force ◽  
Bending Strain ◽  
Pendulum Dynamics ◽  
Good Agreement

An empirical formula which has been shown to give good values for ring bending strain in small rings has been applied to infrared bending vibrations. The derived dynamics are of a ?pendulum? character, and reasonable agreement is obtained in calculating the C-C-C bending force constant from the empirical formula constant. Resultant anharmonicities are calculated from the ?pendulum? dynamics, and good agreement is obtained with experimentally determined levels up to the 060 level of CO2 and 040 for HCN.

scholarly journals INTERATOMIC INTERACTIONS AND ZONE CENTRE PHONONS IN MULTIFERROIC BiFeO3 CERAMICS

2013 ◽  
Vol 22 ◽  
pp. 134-139 ◽  
Author(s):  
M. M. SINHA ◽  
RUBY ◽  
H. C. GUPTA
Keyword(s):  
Force Constant ◽  
Ferroelectric Properties ◽  
Compressive Strain ◽  
Potential Energy Distribution ◽  
Bending Force ◽  
Short Range Force ◽  
Multiferroic Bifeo3 ◽  
Zone Centre ◽  
Range Force ◽  
Good Agreement

The existence of an epitaxially stabilized tetragonal-like (“T -like”) monoclinic phase in BiFeO 3 thin films with high levels of compressive strain has been reported recently. While their structural and ferroelectric properties are different from those of rhombohedral-like (“R-like”) films with lower levels of strain, little information exists on magnetic properties. In this study we have applied a short range force constant model by using normal coordinates to investigate the Raman and the infrared wavenumbers in tetragonal BiFeO 3 having space group P4mm (C4v1). The calculation of zone center phonons has been made by using three stretching and six bending force constants. The calculated Raman and infrared wavenumbers are in very good agreement with the observed ones. The potential energy distribution has also been investigated for determining the significance of contribution from each force constant toward the Raman and the infrared wavenumbers.

scholarly journals Study of Influence of Width to Thickness Ratio in Sheet Metals on Bendability under Ambient and Superimposed Hydrostatic Pressure

2021 ◽  
Vol 2 (3) ◽  
pp. 542-558
Author(s):  
Mohammadmehdi Shahzamanian ◽  
David Lloyd ◽  
Amir Partovi ◽  
Peidong Wu
Keyword(s):  
Hydrostatic Pressure ◽  
Stress Ratio ◽  
Fracture Strain ◽  
Stress Triaxiality ◽  
Volumetric Strain ◽  
Thickness Ratio ◽  
Sheet Metals ◽  
The Finite Element Method ◽  
Bending Strain ◽  
Good Agreement

The effect of the width to thickness ratio on the bendability of sheet metal is investigated using the finite element method (FEM) employing the Gurson–Tvergaard–Needleman (GTN) model. Strain path changes in the sheet with change in the width/thickness ratio. It is shown that bendability and fracture strain increase significantly by decrease in the width/thickness ratio. The stress state is almost uniaxial when the stress ratio (α) is close to zero for narrow sheets. Stress ratio is nothing but the major stress to minor stress ratio. This delays the growth and coalescence of micro-voids as the volumetric strain and stress triaxiality (pressure/effective stress) decrease. On the other hand, ductility decreases with increase in α for wider sheets. Fracture bending strain is calculated and, as expected, it increases with decrease in the width/thickness ratio. Furthermore, a brief study is performed to understand the effect of superimposed hydrostatic pressure on fracture strain for various sheet metals with different width/thickness ratios. It is found that the superimposed hydrostatic pressure increases the ductility, and that the effect of the width/thickness ratio in metals on ductility is as significant as the effect of superimposed hydrostatic pressure. Numerical results are found to be in good agreement with experimental observations.

scholarly journals Normal spectral emissivity of liquid Al-Ti binary alloys

2020 ◽  
Vol 48 (5-6) ◽  
pp. 423-438
Author(s):  
JUERGEN BRILLO ◽  
JOHANNA J. WESSING ◽  
HIDEKAZU KOBATAKE ◽  
HIROYUKI FUKUYAMA
Keyword(s):  
Temperature Dependence ◽  
Reasonable Agreement ◽  
Spectral Emissivity ◽  
Liquid System ◽  
Normal Spectral Emissivity ◽  
Binary Liquid System ◽  
Binary Liquid ◽  
Electrical Resistivities ◽  
Existing Data ◽  
Good Agreement

The normal spectral emissivity ε of four compositions in the Al-Ti binary liquid system was measured in dependence of the wavelength and temperature. It was found that all compositions show negligible temperature dependence. At a wavelength of 940 nm, the emissivity amounts to 0.37, 0.40, 0.32, and 0.31 for Ti, Al20Ti80, Al50Ti50, and Al70Ti30, respectively. The dependence of the emissivity on composition is in good agreement with literature data of binary and multi-component Al-Ti-based alloys. Using the classical Drude model, electrical resistivities are predicted for the Al-Ti system from the measured emissivities. Comparison with existing data from literature for Al show reasonable agreement.

Modeling the flow around and the hydrodynamic drag on net meshes using REEF3D

2021 ◽  
pp. 1-21
Author(s):  
Gang Wang ◽  
Tobias Martin ◽  
Liuyi Huang ◽  
Hans Bihs
Keyword(s):  
Open Source ◽  
Empirical Formula ◽  
Hydrodynamic Forces ◽  
Hydrodynamic Drag ◽  
Hydrodynamic Coefficients ◽  
Flume Experiments ◽  
Simulation Accuracy ◽  
Flow Interactions ◽  
Fluid Properties ◽  
Good Agreement

Abstract The hydrodynamics and flow around net meshes has recently drawn more and more attention because it is closely related to the expected forces on aquaculture. In terms of modelling the hydrodynamic forces on nets, Morison or screen force models are ordinarily. However, they mainly rely on empirical, experimental or cylindrical hydrodynamic coefficients, neglecting the flow interactions between adjacent net twines. In this study, the open-source hydrodynamic toolbox REEF3D is adopted to analyze the flow around net meshes and investigate the hydrodynamic drag on the structure. The simulation accuracy is in good agreement with flume experiments and previous research. The results demonstrate that 2 × 2 or 3 × 3 mesh cases are more reliable for studying the flow around net meshes including the flow interactions around adjacent twines. It is further shown that controlling the solidity of the net through changing net bar diameters has different effects on the flow around meshes than controlling it by the twine length. This paper presents a first step in the aim to derive a new empirical formula for the drag coefficients depending on the solidity and fluid properties which is more appropriate for to the physics involved in offshore conditions.

The Mixing Length Derived from Kármán’s Similarity Hypothesis

1973 ◽  
Vol 24 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Michio Nishioka ◽  
Shūsuke Iida
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Reasonable Agreement ◽  
Diffusion Constant ◽  
Turbulent Shear ◽  
Appreciable Effect ◽  
Mixing Length ◽  
Similarity Hypothesis ◽  
Turbulent Shear Stress ◽  
Good Agreement

SummaryFrom Kármán’s similarity hypothesis, we derive the equation which describes the mixing length in terms of the turbulent shear stress. For a boundary layer with linear stress distribution, the equation is in reasonable agreement with Bradshaw’s measurements. For a boundary layer with injection, it is shown that injection has an appreciable effect upon the mixing length when (vw/2) /(τ/ρ)1/2becomes comparable to the Kármán constant. Close similarity is also pointed out between the hypotheses due to Kármán and Townsend. Moreover, the diffusion constant in Townsend’s hypothesis is determined to be 0.25, which is in good agreement with the value 0.2 obtained by Townsend from one experiment.

AN EMPIRICAL FORMULA FOR Q STATE POTTS MODEL IN D DIMENSIONS

1994 ◽  
Vol 08 (17) ◽  
pp. 1059-1064
Author(s):  
C. Y. PAN
Keyword(s):  
Renormalization Group ◽  
Critical Points ◽  
Potts Model ◽  
Critical Exponents ◽  
Empirical Formula ◽  
Group Method ◽  
Critical Properties ◽  
Renormalization Group Method ◽  
Primary Reference ◽  
Good Agreement

Based upon the known results of the critical properties of the q state Potts ferromagnets obtained by different methods, we proposed an empirical formula of the model. It gives the critical points and the critical exponents for general Potts spin value q in any d dimensions which are in good agreement with all the available results. It improves the results given by Migdal–Kadanoff renormalization group method. It gives more accurate results than Hajdukovic conjecture to the problem of interest. This empirical formula may serve as the primary reference to the problem of interest.

Etude par spectrométrie de vibration des composés d'addition formés entre le chlorure ou le bromure d'aluminium et le dimethylsulfoxyde

1972 ◽  
Vol 50 (8) ◽  
pp. 1157-1166 ◽  
Author(s):  
J. Meunier ◽  
M. T. Forel
Keyword(s):  
Force Constant ◽  
Strong Interaction ◽  
Coordination Compounds ◽  
Methyl Groups ◽  
Compound I ◽  
Vibration Spectra ◽  
Complete Assignment ◽  
Solid Compounds ◽  
Compound Ii ◽  
Good Agreement

Coordination compounds between AlCl3 or AlBr3 and (CH3)2SO or (CD3)2SO have been prepared. Two different solid compounds (AlX3)• (dmso)1.5 and AlX3• (dmso)6 have been characterized. The vibration spectra show that they are ionic, [Formula: see text] (I) and [Al(dmso)6]3+•3X− (II). A complete assignment is proposed. Results are in good agreement with a D3d symmetry for the cation of compound (I) and C2h for the cation of compound (II). Strong interaction between the X− ions and the methyl groups of the form (II) exist.The (Al—O) bond force constant is close to 1.8 × 105 dynes cm−1.

ANHARMONIC EFFECTIVE POTENTIAL, LOCAL FORCE CONSTANT AND EXAFS OF HCP CRYSTALS: THEORY AND COMPARISON TO EXPERIMENT

2008 ◽  
Vol 22 (29) ◽  
pp. 5155-5166 ◽  
Author(s):  
NGUYEN VAN HUNG ◽  
TONG SY TIEN ◽  
LE HAI HUNG ◽  
RONALD R. FRAHM
Keyword(s):  
Thermal Expansion ◽  
Fine Structure ◽  
Thermal Expansion Coefficient ◽  
Force Constant ◽  
Expansion Coefficient ◽  
Effective Potential ◽  
X Ray ◽  
X Ray Absorption ◽  
Analytical Expressions ◽  
Good Agreement

Anharmonic effective potential, Extended X-ray Absorption Fine Structure (EXAFS) and its parameters of hcp crystals have been theoretically and experimentally studied. Analytical expressions for the anharmonic effective potential, effective local force constant, three first cumulants, a novel anharmonic factor, thermal expansion coefficient and anhamonic contributions to EXAFS amplitude and phase have been derived. This anharmonic theory is applied to analyze the EXAFS of Zn and Cd at 77 K and 300 K, measured at HASYLAB (DESY, Germany). Numerical results are found to be in good agreement with experiment, where unnegligible anharmonic effects have been shown in the considered theoretical and experimental quantities.

A new empirical formula for cross-sections of (n,nα) reactions

2020 ◽  
Vol 29 (08) ◽  
pp. 2050062
Author(s):  
Mustafa Yiğit
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Empirical Formula ◽  
Nuclear Reactions ◽  
Measured Cross Section ◽  
Future Studies ◽  
Present Formalism ◽  
The Cross ◽  
Neutron Cross Sections ◽  
Good Agreement

Studies on the cross-sections of (n,n[Formula: see text]) reactions which are energetically possible, about 14 MeV neutrons are quite scarce. In this paper, the cross-sections of (n,n[Formula: see text] nuclear reactions at [Formula: see text]14–15 MeV are analyzed by using a new empirical formula based on the statistical theory. We show that neutron cross-sections are closely related to the [Formula: see text]-value of nuclear reaction, in particular for (n,n[Formula: see text]) channels. Results obtained with this empirical formula show good agreement with the available measured cross-section values. We hope that the estimations on the cross-sections using the present formalism may be helpful in future studies in this field.

Sign in / Sign up

Export Citation Format

Share Document