scholarly journals A Semi-empirical Model of Air Waves Induced by Falling Rock in a Closed Goaf

2017 ◽  
Author(s):  
Fengyu Ren ◽  
Yang Liu ◽  
Jianli Cao ◽  
Rongxing He ◽  
Yuan Xu ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Phase Velocity ◽  
Empirical Model ◽  
Close Agreement ◽  
Experimental Results ◽  
Uniform Motion ◽  
Protective Measures ◽  
Series Of Experiments ◽  
Semi Empirical ◽  
Wave Induced

In this paper, a semi-empirical model of air waves induced by falling rock is described. The model is composed of a uniform motion phase (velocity close to 0 m·s-1) and an acceleration movement phase. The uniform motion phase was determined based on experimentally and the acceleration movement phase was derived by theoretical analysis. A series of experiments were performed to verify the semi-empirical model and elucidated the law of the uniform motion phase. The acceleration movement phase accounted for a larger portion with a greater height of the falling rock. Experimental results of different falling heights of the goaf showed close agreement with theoretical analysis values. The semi-empirical model could accurately and conveniently estimate the velocity of air wave induced by falling rock. Thus, the semi-empirical model can provide a reference and basis for estimating the speed of air waves and designing protective measures in mines.

scholarly journals A Two-Phase Model of Air Shock Wave Induced by Rock-Fall in Closed Goaf

2017 ◽  
Author(s):  
Fengyu Ren ◽  
Yang Liu ◽  
Jianli Cao ◽  
Rongxing He ◽  
Yuan Xu ◽  
...  
Keyword(s):  
Shock Wave ◽  
Theoretical Analysis ◽  
Phase Model ◽  
Rock Fall ◽  
Uniform Motion ◽  
Two Phase ◽  
Protective Measures ◽  
Computational Fluid Dynamics Cfd ◽  
Series Of Experiments ◽  
Wave Induced

In this paper, a two-phase model of air shock wave induced by rock-fall was described. The model was made up of the uniform motion phase (velocity was close to 0 m·s-1) and the acceleration movement phase. The uniform motion phase was determined by experience, meanwhile the acceleration movement phase was derived by the theoretical analysis. A series of experiments were performed to verify the two-phase model and obtained the law of the uniform motion phase. The acceleration movement phase was taking a larger portion when height of rock-fall was higher with the observations. Experimental results of different falling heights showed good agreements with theoretical analysis values. Computational fluid dynamics (CFD) numerical simulation had been carried out to study the variation velocity with different falling height. As a result of this, the two-phase model could accurately and convenient estimating the velocity of air shock wave induced by rock-fall. The two-phase model could provide a reference and basis for estimating the air shock waves' velocity and designing the protective measures.

scholarly journals A Two-phase Model of Air Shock Wave Induced by Rock-fall in Closed Goaf

2016 ◽  
Author(s):  
Fengyu Ren ◽  
Yang Liu ◽  
Jianli Cao ◽  
Rongxing He ◽  
Yuan Xu ◽  
...  
Keyword(s):  
Shock Wave ◽  
Theoretical Analysis ◽  
Phase Model ◽  
Rock Fall ◽  
Uniform Motion ◽  
Two Phase ◽  
Protective Measures ◽  
Computational Fluid Dynamics Cfd ◽  
Series Of Experiments ◽  
Wave Induced

In this paper, a two-phase model of air shock wave induced by rock-fall in closed goaf was proposed. The model was made up of the uniform motion phase (velocity was close to 0 m•s-1) and the acceleration movement phase. The uniform motion phase was determined by experience and the acceleration movement phase was derived by the theoretical analysis. After this, a series of experiments were performed to verify the two-phase model and obtained the law of the uniform motion phase. By observing, the acceleration movement phase was taking a larger portion and the uniform motion phase was smaller when height of rock-fall was higher. By comparison, experimental results of different falling heights showed good agreements with theoretical analysis, which verifies the effectiveness of the two-phase model. Finally, the model was tested with computational fluid dynamics (CFD) numerical simulation by three groups of different falling height. The two-phase model could provide a reference and basis for estimating the air shock waves' velocity and design the protective measures.

On the Mechanics of Wire Drawing

1961 ◽  
Vol 83 (4) ◽  
pp. 523-529 ◽  
Author(s):  
C. T. Yang
Keyword(s):  
Theoretical Analysis ◽  
Shear Deformation ◽  
Coefficient Of Friction ◽  
Close Agreement ◽  
Wire Drawing ◽  
Experimental Results ◽  
Strain Gages ◽  
Drawing Force ◽  
The Coefficient Of Friction ◽  
Wire Resistance

Split-die technique was adopted to find the coefficient of friction in wire drawing directly from experiment. Simple dynamometers with wire resistance strain gages were used for measuring separating force and drawing force instead of cumbersome equipment used by former researchers. Reasonably good results were obtained. The effect of the land or parallel portion in the die on the coefficient of friction was indicated in the results. Its importance was emphasized. A theoretical equation of the drawing stress with the effect of land considered was derived. Using the coefficient of friction obtained by the split-die method, drawing stresses were calculated from the derived equation. A comparison of the theoretical and experimental drawing stresses was made. Results were tabulated and plotted. It was concluded that including the land in the analysis of wire drawing is important and further research in analyzing the shear deformation must be pursued in order to get a close agreement between theoretical analysis and experimental results.

Displacement damage effects in InGaAs detectors: experimental results and semi-empirical model prediction

2000 ◽  
Vol 47 (6) ◽  
pp. 2466-2472 ◽  
Author(s):  
S. Barde ◽  
R. Ecoffet ◽  
J. Costeraste ◽  
A. Meygret ◽  
X. Hugon
Keyword(s):  
Model Prediction ◽  
Empirical Model ◽  
Experimental Results ◽  
Displacement Damage ◽  
Semi Empirical

Semi-empirical modeling and optimization of process parameters on overcut during MFAPM-EDM of Al6061 alloy

2021 ◽  
pp. 095440892110158
Author(s):  
Arun Kumar Rouniyar ◽  
Pragya Shandilya
Keyword(s):  
Magnetic Field ◽  
Process Parameters ◽  
Empirical Model ◽  
Discharge Current ◽  
Desirability Function ◽  
Experimental Results ◽  
Empirical Modeling ◽  
Machining Process ◽  
Optimum Process ◽  
Semi Empirical

Magnetic field assisted powder mixed electrical discharge machining (MFAPM-EDM) process is a hybrid process machining process which improves the machining characteristics and stability of process using assistive magnetic field and dielectric admixed powder. In this article, study on overcut has been performed on MFAPM-EDM machined Aluminium 6061 alloy. Discharge current, powder concentration, pulse on duration, pulse off duration, and magnetic field strength as process parameters have been varied during experimentation. Box Behnken design approach was employed for experimental design to carry out the experiments. Suitable Semi-empirical model was formulated using dimensional analysis for predicting the overcut. The empirical model developed was also compared with RSM model and was found better in predicting the response. Optimum process parameters for minimal overcut was conducted desirability function approach of RSM. Experimental results divulged discharge current as the most important parameters for overcut as compared to other process parameters on account of higher F-value. Confirmatory experiments revealed good correlation between optimum and experimental results.

scholarly journals Experimental Study for Wave-Induced Pore-Water Pressures in a Porous Seabed around a Mono-Pile

2019 ◽  
Vol 7 (7) ◽  
pp. 237 ◽  
Author(s):  
Shaohua Wang ◽  
Pandi Wang ◽  
Hualing Zhai ◽  
Qibo Zhang ◽  
Linya Chen ◽  
...  
Keyword(s):  
Experimental Study ◽  
Spatial Distribution ◽  
Pore Pressure ◽  
Pore Water ◽  
Wave Height ◽  
Experimental Results ◽  
Period Increase ◽  
Pore Water Pressures ◽  
Series Of Experiments ◽  
Wave Induced

In this paper, the results of a series of experiments on wave-induced pore-water pressures around a mono-pile are presented. Unlike the previous study, in which the mono-pile was fully buried, the mono-pile in this study was installed at 0.6 m below the seabed surface. In this study, we focus on the pore-water pressures around the mono-pile and beneath the pile. The experimental results lead to the following conclusions: (1) the seabed response is more pronounced near the surface (in the region above 30 cm deep), and the rate of pore pressure attenuation gradually slows down. For the region below 0.3 m, the response is much smaller; (2) in general, along the surface of the pile, pore pressures increase as the wave height and wave period increase; (3) the spatial distribution of pore pressure near the pile will vary with different wave periods, while the wave height only has a significant effect on the amplitude; and (4) At z = −0.15 m, the pore pressure in front of the pile is the largest, while at the point 0.1 m below the bottom of the pile, the largest pore pressure occurs behind the pile.

Viscoelastic Boundary Damping of Beams and Plates

1964 ◽  
Vol 31 (1) ◽  
pp. 61-71 ◽  
Author(s):  
T. J. Mentel
Keyword(s):  
Energy Dissipation ◽  
Theoretical Analysis ◽  
Experimental Results ◽  
Elementary Level ◽  
Circular Plates ◽  
Principal Characteristics ◽  
Boundary Damping ◽  
Series Of Experiments

A series of experiments on boundary, damped beams are described which identify separately the effectiveness of axial and transverse motions of the embedded beam ends in producing energy dissipation. A comparatively elementary level of theoretical analysis is shown to be adequate in explaining most of the experimental results. A subsequent series of experiments is then described which tests the damping effectiveness of a small inset of viscoelastic adhesive at the supports of beams and plates, the inset design being motivated by the results of the first experiments. The principal characteristics of the inset design are determined experimentally and a supporting theory (for beams and circular plates) is outlined.

Thermal Contact Conductance of Non-Flat, Rough, Metallic Coated Metals

2002 ◽  
Vol 124 (3) ◽  
pp. 405-412 ◽  
Author(s):  
M. A. Lambert ◽  
L. S. Fletcher
Keyword(s):  
Empirical Model ◽  
Nuclear Reactor ◽  
Combustion Engine ◽  
Thermal Contact ◽  
Theoretical Models ◽  
Thermal Control ◽  
Experimental Results ◽  
Thermal Contact Conductance ◽  
Contact Conductance ◽  
Semi Empirical

Thermal contact conductance is an important consideration in such applications as nuclear reactor cooling, electronics packaging, spacecraft thermal control, and gas turbine and internal combustion engine cooling. In many instances, the highest possible thermal contact conductance is desired. For this reason, soft, high conductivity, metallic coatings are sometimes applied to contacting surfaces (often metallic) to increase thermal contact conductance. O’Callaghan et al. (1981) as well as Antonetti and Yovanovich (1985, 1988) developed theoretical models for thermal contact conductance of metallic coated metals, both of which have proven accurate for flat, rough surfaces. However, these theories often substantially overpredict the conductance of non-flat, rough, metallic coated metals. In the present investigation, a semi-empirical model for flat and non-flat, rough, uncoated metals, previously developed by Lambert and Fletcher (1996), is employed in predicting the conductance of flat and non-flat, rough, metallic coated metals. The models of Antonetti and Yovanovich (1985, 1988) and Lambert and Fletcher (1996) are compared to experimental data from a number of investigations in the literature. This entailed analyzing the results for a number of metallic coating/substrate combinations on surfaces with widely varying flatness and roughness. Both models agree well with experimental results for flat, rough, metallic coated metals. However, the semi-empirical model by Lambert and Fletcher (1996) is more conservative than the theoretical model by Antonetti and Yovanovich (1985, 1988) when compared to the majority of experimental results for non-flat, rough, metallic coated metals.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

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