scholarly journals Analysis of Acoustic Wave Frequency Spectrum Characters of Rock Mass under Blasting Damage Based on the HHT Method

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Haiping Yuan ◽  
Xiaole Liu ◽  
Yan Liu ◽  
Hanbing Bian ◽  
Wen Chen ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Time Lag ◽  
Three Dimensional ◽  
Blasting Vibration ◽  
Accurate Identification ◽  
Transform Method ◽  
Heisenberg Uncertainty Principle ◽  
Vibration Signals ◽  
Nonstationary Signals ◽  
Instantaneous Energy

The limitation associated with Fourier transform and wavelet analysis that they often fail to produce satisfactory resolution simultaneously in time and frequency when dealing with nonlinear and nonstationary signals is frequently encountered. Therefore, this paper aims at using the HHT (Hilbert–Huang transform) method, which is built on the basis of the EMD- (empirical mode decomposition-) based wavelet threshold denoising technique and the Hilbert transform, to analyze the blasting vibration signals in a south China lead-zinc mine. The analysis is conducted in terms of three-dimensional Hilbert spectrum, marginal spectrum, and instantaneous energy spectrum. The results indicate that the frequencies of the blasting vibration signals lie mainly within 0∼200 Hz, which consists of more than 90% of the total signal energy. At the onset of the blasting, the vibration frequency tends to be low, with the frequency that is less than 50 Hz being dominant. By using instantaneous energy spectrum, which can reveal the condition of energy release for detonator explosion, the initiation moments of detonators with 7 time-lag levels are accurately identified. This accurate identification demonstrates the superiority of the HHT method in coping with nonlinear and nonstationary signals. Additionally, the HHT method that is characterized by adaptivity, completeness, strong reconfigurability, and high accuracy provides an opportunity for reflecting signals’ change features with regard to time domain, frequency domain, and energy irrespective of the limitation of the Heisenberg uncertainty principle.

Blast-Induced Cumulative Effects in Surrounding Rock of Largespan Tunnel under Multiple Blasts

2011 ◽  
Vol 378-379 ◽  
pp. 498-501
Author(s):  
Li Feng Li ◽  
Xi Bing Li ◽  
Hai Peng Ma ◽  
Jiang Feng Xie
Keyword(s):  
Damage Evolution ◽  
Surrounding Rock ◽  
Cumulative Effects ◽  
Blasting Vibration ◽  
Transform Method ◽  
Vibration Signals ◽  
Hilbert Huang Transform ◽  
Safety Distance ◽  
Canadian Company ◽  
Instantaneous Energy

The blasting vibration derived from multiple blasts and its effects on surrounding rock in a longspan tunnel will probably give rise to cumulative damage of surrounding rock, and weaken surrounding rock’s stability. Blastmate III, made by the Canadian company Instantel, is utilized to monitor the vibration signals from multiple blasts. Blasting vibration decay law and allowed safety distance of blasting are calculated by using Sadaovsk formula. Then, cumulative effects are analyzed by Hilbert-Huang Transform method as well as consequential instantaneous energy spectrum, and UTEP is presented to indicate the change of cumulative effects and damage in surrouding rock. The research shows that during the progress of damage evolution, “strengthening” and” deteriorating” may alternately appear several times. This is a zigzag reciprocating process in damage evolution of surrounding rock.

scholarly journals A system for generating virtual seeds

1998 ◽  
Vol 55 (spe) ◽  
pp. 39-45 ◽  
Author(s):  
Y. Sako ◽  
K. Fujimura ◽  
M.B. McDonald ◽  
D. James
Keyword(s):  
Three Dimensional ◽  
Promising Method ◽  
Two Dimensional ◽  
Dimensional Representation ◽  
Accurate Identification ◽  
Computer Screen ◽  
Three Dimensional Objects ◽  
Three Dimensional Representation ◽  
Quicktime Vr

Seed analysts need to identify seeds, and seed catalogs are used as a reference to accomplish this task. Conventional seed catalogs supply two-dimensional photographs and hand-drawn diagrams. In this study, a new, three-dimensional representation of seeds is developed to supplement these traditional photographs and drawings. QuickTime VR is a promising method for viewing three-dimensional objects on a computer screen. It permits manipulation of an object by rotating and viewing it from any pre-specified angle at an interactive speed, allowing the viewer the sense of examining a hand-held object. In this study, QuickTime VR object movies of seeds were created as interactive "movies" of seeds that can be rotated and scaled to give the viewer the sensation of examining actual seeds. This approach allows the examination of virtual seeds from any angle, permitting more accurate identification of seeds by seed analysts.

Reduced-order analysis of an oil-fuel furnace vibration and comparison with the finite element method

2018 ◽  
Vol 25 (2) ◽  
pp. 298-309
Author(s):  
Hao Zhou ◽  
Sheng Meng ◽  
Chunhong Mo ◽  
Lujun Wang ◽  
Xiukui Hu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Gas Turbines ◽  
Time Lag ◽  
Three Dimensional ◽  
Longitudinal Mode ◽  
Reduced Order ◽  
Separation Plate ◽  
Oil Fuel ◽  
Element Method

Thermoacoustic oscillation occurs in modern industrial furnaces, gas turbines, and liquid rockets. However, the thermoacoustic prediction tools for furnaces vibration are less developed. This paper presents a one-dimensional (1D) linear acoustic approach to analyze the three-dimensional acoustic modes of a 660 MWe oil-fuel furnace. The interaction between the flame and acoustic field is described with the flame transfer function. The global time delay is evaluated through a Reynolds averaged simulation. The results of the 1D acoustic approach are compared with real furnace test data. The unstable modes are close to the natural modes of the furnace, and the 30 Hz in the longitudinal mode is the strongest vibration frequency. The effects of inlet length reduction and separation plate removal are also examined. When the separation plates are removed, the time lag of flame in response to inlet flow decreases from 52.5 milliseconds (ms) to 43.8 ms. The results of the 1D approach and finite element method (FEM) show a same safe operation window. The reduced-order procedure and FEM adopted in this study give us a solution to mitigate the vibration in the furnace.

scholarly journals Construction of potential functions associated with a given energy spectrum — An inverse problem

2020 ◽  
Vol 35 (20) ◽  
pp. 2050104
Author(s):  
A. D. Alhaidari
Keyword(s):  
Energy Spectrum ◽  
Three Dimensional ◽  
Logarithmic Potential ◽  
Potential Functions ◽  
Physical Parameters ◽  
Linear Potential ◽  
Hahn Polynomial ◽  
Exactly Solvable ◽  
The One ◽  
Solvable Problems

Using a formulation of quantum mechanics based on orthogonal polynomials in the energy and physical parameters, we present a method that gives the class of potential functions for exactly solvable problems corresponding to a given energy spectrum. In this work, we study the class of problems associated with the continuous dual Hahn polynomial. These include the one-dimensional logarithmic potential and the three-dimensional Coulomb plus linear potential.

scholarly journals Klein–Gordon particle near RN black hole, generalized sl(2) algebra and harmonic oscillator energy

2019 ◽  
Vol 34 (31) ◽  
pp. 1950196
Author(s):  
J. Sadeghi ◽  
M. R. Alipour
Keyword(s):  
Differential Equation ◽  
Information Theory ◽  
Black Hole ◽  
Energy Spectrum ◽  
Harmonic Oscillator ◽  
Three Dimensional ◽  
The Other ◽  
Thermodynamical Properties ◽  
Heun Functions ◽  
Klein Gordon

In this paper, we consider Klein–Gordon particle near Reissner–Nordström black hole. The symmetry of such a background led us to compare the corresponding Laplace equation with the generalized Heun functions. Such relations help us achieve the generalized [Formula: see text] algebra and some suitable results for describing the above-mentioned symmetry. On the other hand, in case of [Formula: see text], which is near the proximity black hole, we obtain the energy spectrum. When we compare the equation of RN background with Laguerre differential equation, we show that the obtained energy spectrum is same as the three-dimensional harmonic oscillator. So, finally we take advantage of harmonic oscillator energy and make suitable partition function. Such function help us to obtain all thermodynamical properties of black hole. Also, the structure of obtained entropy lead us to have some bit and information theory in the RN black hole.

scholarly journals Experimental and Theoretical Study on Influence of Different Charging Structures on Blasting Vibration Energy

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Wenbin Gu ◽  
Zhenxiong Wang ◽  
Jianghai Chen ◽  
Jianqing Liu ◽  
Ming Lu
Keyword(s):  
Theoretical Study ◽  
Impedance Matching ◽  
Rock Fragmentation ◽  
Vibration Energy ◽  
Blasting Vibration ◽  
High Impedance ◽  
Coupling Structure ◽  
Decoupling Coefficient ◽  
Instantaneous Energy ◽  
Relationship Equation

As an important parameter in blasting design, charging structure directly influences blasting effect. Due to complex conditions of this blasting and excavating engineering in Jiangsu, China, the authors carried out comparative researches with coupling structure, air-decoupling structure, and water-decoupling structure. After collecting, comparing, and analyzing produced signals on blasting vibration, the authors summarized that when proportional distances are the same, water-decoupling structure can reduce instantaneous energy of blasting vibration more effectively with more average rock fragmentation and less harm of dust. From the perspective of impedance matching, the present paper analyzed influence of charging structure on blasting vibration energy, demonstrating that impedance matching relationship between explosive and rock changes because of different charging structures. Through deducing relationship equation that meets the impedance matching of explosive and rock under different charging structures, the research concludes that when blasting rocks with high impedance, explosive with high impedance can better transmits blasting energy. Besides, when employing decoupling charging, there exists a reasonable decoupling coefficient helping realize impedance matching of explosive and rock.

Transient Thermoelastic Stress Fields in a Half-Space

2002 ◽  
Vol 125 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Shuangbiao Liu ◽  
Qian Wang
Keyword(s):  
Stress Field ◽  
Half Space ◽  
Frictional Heating ◽  
Three Dimensional ◽  
Thermoelastic Stress ◽  
Parabolic Type ◽  
Elastic Half Space ◽  
Transform Method ◽  
Rough Surface Contact ◽  
Thermoelastic Stress Field

Computing the thermoelastic stress field of a material subjected to frictional heating is essential for component failure prevention and life prediction. However, the analysis for three-dimensional thermoelastic stress field for tribological problems is not well developed. Furthermore, the pressure distribution due to rough surface contact is irregular; hence the frictional heating can hardly be described by an analytical expression. This paper presents a novel set of frequency-domain expressions (frequency response functions) of the thermoelastic stress field of a uniformly moving three-dimensional elastic half-space subjected to arbitrary transient frictional heating, where the velocity of the half-space, its magnitude and direction, can be an arbitrary function of time. General formulas are expressed in the form of time integrals, and important expressions for constant velocities are given for the transient-instantaneous, transient-continuous, and steady-state cases. The thermoelastic stress field inside a translating half-space with constant velocities are illustrated and discussed by using the discrete convolution and fast Fourier transform method when a parabolic type or an irregularly distributed heat source is applied.

Stationarity test of vibration signals with surrogate data and time–frequency analysis

2016 ◽  
Vol 20 (8) ◽  
pp. 1143-1154
Author(s):  
Zuo-Cai Wang ◽  
Feng Wu ◽  
Wei-Xin Ren
Keyword(s):  
Frequency Analysis ◽  
Surrogate Data ◽  
Transform Method ◽  
Vibration Signals ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Analysis Methods ◽  
Stationarity Test ◽  
Modulated Signals ◽  
Short Time

The stationarity test of vibration signals is critical for the extraction of the signal features. In this article, the surrogate data with various time–frequency analysis methods are proposed for stationary test of vibration signals. The surrogate data are first generated from the Fourier spectrum of the original signal with keeping the magnitude of the spectrum unchanged and replacing its phase by a random sequence. The local and global spectra of the original signal and the surrogate data are then estimated by four time–frequency analysis methods, which are short-time Fourier transform, multitaper spectrograms, wavelet transform, and S-transform methods. The index of nonstationarity is then defined based on the distances between the local and global spectra. Three kinds of synthetic signals, which are stationary signals, frequency-modulated signals, and amplitude-modulated signals, are tested to compare the efficiency of the four time–frequency analysis methods as mentioned. The results show that with a certain observation scale value, the index of nonstationarity based on the short-time Fourier transform or wavelet transform method may fail to test the stationarity of the signal. The parametric studies and sensitivity analysis of the observation scale and noise-level effect are also extensively conducted. The results show that the index of nonstationarity calculated using the multitaper spectrograms’ method is more suitable for stationarity test of frequency-modulated signals, while the index of nonstationarity calculated using the S-transform method is more suitable for stationarity test of amplitude-modulated signals. The results also show that the noise has a significant effect on the stationarity test results. Finally, the stationarity of a real vibration signal measured from a cable is tested, and the results show that the proposed index of nonstationarity can effectively test the stationarity of real vibration signals.

Three-Dimensional Periodic Fully Nonlinear Potential Waves

2013 ◽  
Author(s):  
Dmitry Chalikov ◽  
Alexander V. Babanin
Keyword(s):  
Wave Field ◽  
Degrees Of Freedom ◽  
Velocity Potential ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Transform Method ◽  
Fully Nonlinear ◽  
Stokes Waves ◽  
Nonlinear Potential ◽  
The Fourier Transform

An exact numerical scheme for a long-term simulation of three-dimensional potential fully-nonlinear periodic gravity waves is suggested. The scheme is based on a surface-following non-orthogonal curvilinear coordinate system and does not use the technique based on expansion of the velocity potential. The Poisson equation for the velocity potential is solved iteratively. The Fourier transform method, the second-order accuracy approximation of the vertical derivatives on a stretched vertical grid and the fourth-order Runge-Kutta time stepping are used. The scheme is validated by simulation of steep Stokes waves. The model requires considerable computer resources, but the one-processor version of the model for PC allows us to simulate an evolution of a wave field with thousands degrees of freedom for hundreds of wave periods. The scheme is designed for investigation of the nonlinear two-dimensional surface waves, for generation of extreme waves as well as for the direct calculations of a nonlinear interaction rate. After implementation of the wave breaking parameterization and wind input, the model can be used for the direct simulation of a two-dimensional wave field evolution under the action of wind, nonlinear wave-wave interactions and dissipation. The model can be used for verification of different types of simplified models.

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