scholarly journals Numerical Investigations of the Single-Mode Microwave Treatment Effects on Rock Breakage

2019 ◽  
Author(s):  
Khashayar Teimoori ◽  
Ferri Hassani ◽  
Agus Pulung Sasmito ◽  
Ali Ghoreishi Madiseh
Keyword(s):  
Mechanical Stress ◽  
Power Level ◽  
Single Mode ◽  
Microwave Treatment ◽  
The Finite Element Method ◽  
Rock Breakage ◽  
Rock Model ◽  
Stress Damage ◽  
Breakage Mechanism ◽  
Efficient Selection

In this study, a rock model which consists of a conceptual block (host rock and ore sample) is numerically modeled by using the finite element method. The rock model is subjected to several single-mode microwave treatments with different power levels, distances from the antenna, and exposure times in order to calculate and compare the corresponding effects including temperature distribution and mechanical stress/damage profiles. The main objective of the present study is to analyze the distribution of temperature and mechanical stress at the boundary of two different attached rocks when exposed to microwaves. This enables comparing the intensity of the distribution with respect to the applied microwave input operating parameters and, consequently, understanding rock preconditioning. The results of the present study verify that an increase in temperature by microwave treatment facilitates the rock weakening process. Also, a more efficient selection of the distance from the antenna and the power level can maximize the overall impact of the microwave treatment on rock preconditioning which ultimately helps with the rock breakage mechanism. 

scholarly journals Experimental Investigations of Microwave Effects on Rock Breakage Using SEM Analysis

2019 ◽  
Author(s):  
Khashayar Teimoori ◽  
Ferri Hassani ◽  
Agus Pulung Sasmito ◽  
Ali Ghoreishi Madiseh
Keyword(s):  
Crack Density ◽  
Mechanical Damage ◽  
Single Mode ◽  
Microwave Treatment ◽  
Crack Size ◽  
Sem Analysis ◽  
Experimental Investigations ◽  
Operating Parameters ◽  
Rock Breakage ◽  
Microscopy Imaging

Preconditioning of hard rocks by microwave energy has recently been considered a potentially effective technology in mechanical rock breakage for civil and mining engineering. To obtain the amount of mechanical damage that a single-mode microwave treatment produces in rocks, it is necessary to analyze and evaluate the thermal cracking process by microwave heating at different power levels, exposure times, and distances from the antenna. The current study employs the scanning electron microscopy imaging technique to capture images from surfaces of irradiated rock specimens and to compare them with a nontreated specimen. To evaluate and quantify the amount of cracking (i.e. crack density, crack size, etc.) in a rock specimen after microwave irradiation with different microwave input operating parameters, the following steps were evaluated. First, several experiments of single-mode microwave treatments with different operating parameters were performed on rectangular specimens of basalt. Then, cylindrical core samples with a dimension of r = 0.5 cm, h = 2cm, were drilled from the center of the irradiated specimens and prepared for image processing. The results of the present study show that there are significant differences between the number of microcracks present in samples irradiated at different power levels and distances from the antenna. Also, longer exposure times result in more severe cracks.

Vibration of Nonuniform Beams Under Moving Point Loads: An Approximate Analytical Solution in Time Domain

2017 ◽  
Vol 17 (03) ◽  
pp. 1750035 ◽  
Author(s):  
C. P. Sudheesh Kumar ◽  
C. Sujatha ◽  
K. Shankar
Keyword(s):  
Approximate Analytical Solution ◽  
Time Integration ◽  
Single Mode ◽  
Mode Analysis ◽  
Moving Loads ◽  
The Finite Element Method ◽  
Require Time ◽  
Analytical Formulae ◽  
Clamped Beams ◽  
Forced Responses

The forced-free responses of nonuniform beams under moving point loads are analyzed in this paper. Simple approximate analytical formulae for the forced responses of undamped nonuniform beams, derived using the fundamental mode by the Rayleigh–Ritz (R–R) method, are presented. The responses of both simply supported and clamped–clamped beams are analyzed. The responses are also determined by the finite element method (FEM) in which nonuniform elements are used for fast convergence. It is found that the present method yields results that are very close to those obtained by the FEM. As this method does not require time integration, it is faster and computationally more efficient. Though the single-mode analysis of forced vibration of uniform beams under moving loads has been done by several researchers, its application to nonuniform beams has not been reported.

Microwave-Assisted Grinding of Bolkardag (Nigde, Turkey) Gold Ore and Enhanced Cyanide Leachability

2018 ◽  
Vol 115 (5) ◽  
pp. 508 ◽  
Author(s):  
Cemaliye Seflek ◽  
Oktay Bayat
Keyword(s):  
Particle Size ◽  
Power Level ◽  
Microwave Treatment ◽  
Cyanide Leaching ◽  
Gold Ore ◽  
Work Index ◽  
Significant Difference ◽  
Bond Work Index ◽  
Pre Treatment ◽  
Silver Extraction

This experimental work aims at studying the effect of particle size on the microwave pre-treatment for the grindability of Bolkardag (Nigde, Turkey) gold ore for cyanide leaching. Three different particle size batches (−8 + 4.7 mm, −4.75 + 2 mm and −2 + 1 mm) were used for microwave treatment. Each sub-samples were exposed to four different power levels of microwave energy (0.09, 0.18, 0.36 and 0.6 kW) at exposure times of 5, 10, 15 and 30 minutes and then grindability characteristic of the treated samples were investigated with Berry and Bruce comparative grindability method. It was clearly seen that increasing power level and exposure time caused a reduction in comparative Bond Work index. A maximum reduction in Bond Work index (73.54%) was achieved by 0.6 kW at 30 minutes of microwave treatment. Compared to the untreated sample’s results, gold and silver extraction rates increased, using microwave-treated samples, about 7% and 9% after 77 hours cyanide leaching, respectively. Additionally, the hydrated lime added samples (after 0.6 kW at 30 minutes of microwave treatment) were used in the cyanide leaching tests to determine the possible effect. It was observed that there was no significant difference on leaching extraction rates using lime free or lime added samples. Applying microwave pre-treatment before cyanide leaching, the gold and silver extraction rates could be increased and also the cost of communition could be reduced due to easier breakage of the ore due to a significant decrease in Bond Work index.

scholarly journals Microdrilled tapers to enhance optical fiber lasers for sensing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. A. Perez-Herrera ◽  
M. Bravo ◽  
P. Roldan-Varona ◽  
D. Leandro ◽  
L. Rodriguez-Cobo ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Fiber Lasers ◽  
Signal To Noise Ratio ◽  
Power Level ◽  
Single Mode ◽  
Optical Signal ◽  
Single Mode Fiber ◽  
Output Power Level ◽  
Linear Cavity

AbstractIn this work, an experimental analysis of the performance of different types of quasi-randomly distributed reflectors inscribed into a single-mode fiber as a sensing mirror is presented. These artificially-controlled backscattering fiber reflectors are used in short linear cavity fiber lasers. In particular, laser emission and sensor application features are analyzed when employing optical tapered fibers, micro-drilled optical fibers and 50 μm-waist or 100 μm-waist micro-drilled tapered fibers (MDTF). Single-wavelength laser with an output power level of about 8.2 dBm and an optical signal-to-noise ratio of 45 dB were measured when employing a 50 μm-waist micro-drilled tapered optical fiber. The achieved temperature sensitivities were similar to those of FBGs; however, the strain sensitivity improved more than one order of magnitude in comparison with FBG sensors, attaining slope sensitivities as good as 18.1 pm/με when using a 50 μm-waist MDTF as distributed reflector.

scholarly journals Stress Analysis of Polarization Maintaining Optical Fibers by the Finite Element Method

1970 ◽  
Vol 1 (1) ◽  
Author(s):  
M. H. Aly A. S. Farahat, M. S. Helmi and M. Farhoud
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Optical Fibers ◽  
Radial Distance ◽  
Single Mode ◽  
The Finite Element Method ◽  
Modal Birefringence ◽  
Polarization Maintaining ◽  
External Forces ◽  
Element Method

Stress-induced birefringence in single mode polarization maintaining optical fibers has been investigated using the finite element method. The modal birefringence caused by external forces in the Panda and the Side Tunnel fibers are calculated. It is found that the modal birefringence is directly proportional to the radial distance from the fiber center. As expected, the modal birefringence vanishes with the variation in the magnitude of the applied external loads.Key Words: Birefringence, Polarization, Panda Fiber, Side-Pit Fiber, Finite Element Method.

scholarly journals Dual Polarization-Based Transmitter Configuration Improving Q-Factor for a Single-Mode Fiber Link

2020 ◽  
Vol 8 (5) ◽  
pp. 4286-4289
Keyword(s):  
Optical Fibers ◽  
Power Level ◽  
Phase Variation ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Spectrum Efficiency ◽  
Q Factor ◽  
Nonlinear Optical Effect ◽  
Communication Range ◽  
Fiber Link

The requirement of the modern application is to transmit wide bandwidth of signal with the low latency. The optical fibers provide wide transmission bandwidth along with very little delay as well as choice on choosing transmission medium for high data rate. However, Stimulated Brillouin Scattering (SBS) is a nonlinear optical effect that restricts power level into a fiber to few milliwatts. It degrades the Q-factor and consequently the bit error rate of an optical fiber link. For suppression of SBS, various approaches have been used previously such as PSK, ASK, FSK, CSRZ-DQPSK etc. Among all the previous techniques, CSRZ-DQPSK transmitter is considered as the most efficient one for suppression of SBS. However, it consists of some drawbacks such as low spectrum efficiency, susceptibility to phase variation and short communication range, due to which requirement arises of upgrading the previous work. Therefore, in the proposed work (i.e. CSRZ-DP-QPSK), DP-QPSK scheme is used which makes the system more efficient as it has high spectrum efficiency and improved sensitivity. Also, the communication range is elongated in present work. The performance evaluation of CSRZ-DP-QPSK approach has been performed in terms of Q-Factor, BER, and threshold. Also, the comparative analysis of the proposed approach with conventional approaches has been performed and from the obtained results it has been demonstrated that proposed work is more efficient than conventional one as it has better SBS tolerance and improved BER.

scholarly journals Study on Mesoscale Damage Evolution Characteristics of Irregular Sandstone Particles Based on Digital Images and Fractal Theory

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Lujing Zheng ◽  
Lulin Zheng ◽  
Yujun Zuo ◽  
Hao Liu ◽  
Bin Chen ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Failure Mode ◽  
Damage Evolution ◽  
Fractal Theory ◽  
Rock Breaking ◽  
Rock Breakage ◽  
Damage Degree ◽  
Final Failure ◽  
Fracture Damage ◽  
Breakage Mechanism

To study the mesoscale damage evolution law of irregular sandstone particles, based on RFPA2D and digital image processing technology, a real mesostructure numerical model of irregular sandstone particles is established to simulate the breakage process of particles, the effects of loading conditions and mesoscale heterogeneity on irregular sandstone particle damage are studied, and the calculation method of fractal dimension of irregular rock particles mesoscale fracture is proposed. The results show that the fracture damage degree (ω) and fractal dimension (D) maximum values of the constrained particles are 0.733 and 1.466, respectively, and the unconstrained particles are 0.577 and 1.153, respectively. The final failure mode of constrained particles is more complicated than unconstrained particles, the damage is more serious, and the fracture is more complete. Thus, the larger values of D yield a more complicated final failure mode of the particles. Consequently, with the larger ω, the final damage is more serious, and the breakage effect is comparatively better. The study is of great significance for exploring the laws of rock particle breakage and energy consumption, rock breakage mechanism, and searching for efficient and energy-saving rock-breaking methods.

Optimum design for a novel large mode area fiber with triangle-platform-index core

2019 ◽  
Vol 33 (18) ◽  
pp. 1950207 ◽  
Author(s):  
Xiaofang Miao ◽  
Peng Wu ◽  
Baoyin Zhao
Keyword(s):  
Power Level ◽  
Single Mode ◽  
Output Power Level ◽  
Nonlinear Phenomenon ◽  
Industrial Processing ◽  
Mode Field ◽  
Index Distribution ◽  
Core Fiber ◽  
Mode Area ◽  
Field Area

A triangle-platform-index core fiber is proposed, in which the refractive index distribution in the cross-section of the fiber core is composed of several closely connected triangles and a platform at the outermost layer. The simulation results show that the proposed fiber possesses an extremely large mode field area of [Formula: see text] at the wavelength of [Formula: see text], and achieves single-mode operation state near a bend radius of 17 cm. Furthermore, several different mode field distributions, including Gauss-like distribution, flatten distribution and hollow distribution, are achieved. The proposed fiber can benefit suppressing nonlinear phenomenon to increase the output power level of fiber laser, and promoting special industrial processing.

scholarly journals Theoretical and Numerical Estimation of Vibroacoustic Behavior of Clamped Free Parabolic Tapered Annular Circular Plate with Different Arrangement of Stiffener Patches

2018 ◽  
Vol 8 (12) ◽  
pp. 2542 ◽  
Author(s):  
Abhijeet Chatterjee ◽  
Vinayak Ranjan ◽  
Mohammad Azam ◽  
Mohan Rao
Keyword(s):  
Circular Plate ◽  
Acoustic Radiation ◽  
Power Level ◽  
Radiation Efficiency ◽  
Thickness Variation ◽  
Sound Power ◽  
The Finite Element Method ◽  
Acoustic Response ◽  
Sound Power Level ◽  
Design Options

This paper compares the vibroacoustic behavior of a tapered annular circular plate having different parabolic varying thickness with different combinations of rectangular and concentric stiffener patches keeping the mass of the plate and the patch constant for a clamped-free boundary condition. Both numerical and analytical methods are used to solve the plate. The finite element method (FEM) is used to determine the vibration characteristic and both Rayleigh integral and FEM is used to determine the acoustic behavior of the plate. It is observed that a Case II plate with parabolic decreasing–increasing thickness variation for a plate with different stiffener patches shows reduction in frequency parameter in comparison to other cases. For acoustic response, the variation of peak sound power level for different combinations of stiffener patches is investigated with different taper ratios. It is investigated that Case II plate with parabolic decreasing–increasing thickness variation for an unloaded tapered plate as well as case II plate with 2 rectangular and 4 concentric stiffeners patches shows the maximum sound power level among all variations. However, it is shown that the Case III plate with parabolically increasing–decreasing thickness variation with different combinations of rectangular and concentric stiffeners patches is least prone to acoustic radiation. Furthermore, it is shown that at low forcing frequency, average radiation efficiency with different combinations of stiffeners patches remains the same, but at higher forcing frequency a higher taper ratio causes higher radiation efficiency, and the radiation peak shifts towards the lower frequency and alters its stiffness as the taper ratio increases. Finally, the design options for peak sound power actuation and reduction for different combinations of stiffener patches with different taper ratios are suggested.

Finite Element-Integral Acoustic Simulation of JT15D Turbofan Engine

1984 ◽  
Vol 106 (3) ◽  
pp. 405-413 ◽  
Author(s):  
K. J. Baumeister ◽  
S. J. Horowitz
Keyword(s):  
Finite Element ◽  
Sound Field ◽  
Single Mode ◽  
Solution Technique ◽  
Acoustic Wave Equation ◽  
The Finite Element Method ◽  
Static Test ◽  
Potential Formulation ◽  
Field Radiation ◽  
Good Agreement

An iterative finite element-integral technique is used to predict the sound field radiated from the JT15D turbofan inlet. The sound field is divided into two regions: the sound field within and near the inlet which is computed using the finite element method, and the radiation field beyond the inlet which is calculated using an integral solution technique. The velocity potential formulation of the acoustic wave equation was employed in the program. For some single mode JT15D data, the theory and experiment are in good agreement for the far field radiation pattern as well as suppressor attenuation. Also, the computer program is used to simulate flight effects that cannot be performed on a ground static test stand.

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