scholarly journals Study on Low-Frequency TEM Effect of Coal during Dynamic Rupture

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Cheng-wu Li ◽  
Chuan Wang ◽  
Bei-jing Xie ◽  
Xiao-yuan Sun ◽  
Xiao-meng Xu
Keyword(s):  
High Strain ◽  
Low Frequency ◽  
Test System ◽  
Test Results ◽  
Dynamic Rupture ◽  
Monitoring Technique ◽  
Shpb Test ◽  
Coal Rock ◽  
And Performance ◽  
Electromagnetic Monitoring

Dynamic loads provided by the SHPB test system were applied to coal specimens, and the TEM signals that emerged during coal rupture were recorded by the TMVT system. Experiments on coal-mass blasting rupture in excavating workface were also carried out, and the emerged TEM signal was analyzed. The results indicate that the low-frequency TEM signals were detected close to the coal specimens under high strain dynamic load applied by the SHPB, initially rising sharply and dropping rapidly, followed by a small tailing turbulence. And the field test results obtained during coal blasting process coincided with the results from the SHPB tests. Furthermore, its initial part shaped like a pulse cluster had a more pronounced tail and lasted even longer. And the generation mechanism of the low-frequency TEM effect was analyzed. It suggests that the low-frequency TEM effect of coal during dynamic rupture is contributed by the fractoemission mechanism and the resonance or waveguide effects. Because its wavelength is longer than the higher ones, the low-frequency TEM has a good anti-interference performance. That can expand the scope and performance of the coal-rock dynamic disaster electromagnetic monitoring technique.

Framework and performance analysis of college English testing system based on data mining technology

2021 ◽  
pp. 1-11
Author(s):  
Liu Narengerile ◽  
Li Di ◽  
Keyword(s):  
Data Mining ◽  
Test System ◽  
Test Time ◽  
Testing System ◽  
Test Results ◽  
System Software ◽  
Examination System ◽  
Mining Technology ◽  
College English ◽  
And Performance

At present, the college English testing system has become an indispensable system in many universities. However, the English test system is not highly humanized due to problems such as unreasonable framework structure. This paper combines data mining technology to build a college English test framework. The college English test system software based on data mining mainly realizes the computer program to automatically generate test papers, set the test time to automatically judge the test takers’ test results, and give out results on the spot. The test takers log in to complete the test through the test system software. The examination system software solves the functions of printing test papers, arranging invigilation classrooms, invigilating teachers, invigilating process, collecting test papers, scoring and analyzing test papers in traditional examinations. Finally, this paper analyzes the performance of this paper through experimental research. The research results show that the system constructed in this paper has certain practical effects.

Experiment Analysis about Mechanical Properties of Rubber Bushing for Suspension Telescopic Shock Absorber

2014 ◽  
Vol 670-671 ◽  
pp. 1008-1011 ◽  
Author(s):  
Li Ping Li
Keyword(s):  
High Frequency ◽  
Optimization Design ◽  
Shock Absorber ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Test System ◽  
Test Results ◽  
Static And Dynamic Characteristics ◽  
Rubber Bushing

The experiments of static and dynamic characteristics of rubber bushing for rear suspension telescopic shock absorber were carried out at four directions such as axial, radial, torsion and yaw, by MTS831 and SAGINOMIYA test system. The tests prove that: rubber bushing has great damping, and rubber bushing has obvious nonlinear characteristic; the dynamic stiffness under low frequency and large amplitude excitation is smaller, while the dynamic stiffness under high frequency and small amplitude excitation is greater; at the same amplitude, the dynamic stiffness increases with the increasing excitation frequency. The test results can provide support for the optimization design of rubber bushing.

A New Approach in Testing and Evaluating Micro-Cracking Performance of Electroplated Diamond Film (EDF)

2011 ◽  
Vol 217-218 ◽  
pp. 860-865
Author(s):  
Ying Wu ◽  
Ming Qing Sun ◽  
Zhuo Qiu Li
Keyword(s):  
Diamond Film ◽  
Test System ◽  
Test Results ◽  
New Approach ◽  
Practical Applications ◽  
Economic Method ◽  
Need To Evaluate ◽  
Cracking Performance ◽  
And Performance ◽  
Relative Hardness

Many efforts have been directed to the micro structure and performance evaluation of Electroplated Diamond Film. The indentation method has become extensively utilized in the evaluation of materials’ mechanical. Nano indentation devices, such as MTS-XP, are very useful, but on the other hand, are not affordable for many research institutions. This paper presents an effective and economic method for testing and evaluating micro-cracking performance of Electroplated Diamond Film on Instron 5848 MicroTester by considering the relative hardness values, and the need to evaluate the maximum strength for brittle materials in practical applications. The design of the test system, the evaluation methods, the test results, and the discussions are presented.

scholarly journals The Mechanical Properties of a Smart Compression-Type Isolator Based on Magnetorheological Gel and Magnetorheological Elastomer

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Guo-Jun Yu ◽  
Xi-Xi Wen ◽  
Cheng-Bin Du ◽  
Fei Guo
Keyword(s):  
High Frequency ◽  
Mechanical Model ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Building Structures ◽  
Test Results ◽  
Magnetorheological Elastomer ◽  
High Dynamic ◽  
And Performance ◽  
Compression Type

In order to control the vibration of civil building structures, a smart extrusion-type isolator was developed based on magnetorheological gel (MRG) and magnetorheological elastomer (MRE). The key technology and performance tests of the isolator were investigated as well as the identification of parameters of the mechanical model. Test results showed that the MRG cylinder has a damping characteristic at high frequency while the MRE cylinder has an isolation characteristic at low frequency. The designed isolator is therefore superior over the traditional isolator since it will show small damping and low dynamic stiffness at a high frequency and small amplitude situation, which can overcome stiffness hardening that occurs on the traditional isolator. Meanwhile, the designed isolator will also have the behavior of large isolation and high dynamic stiffness under the low frequency and large amplitude condition, which has the advantage of realizable displacement control. The uniaxial mechanical model for the MRG/MRE smart isolator was built, and the parameters of the designed vibration isolator were identified. Theoretical results obtained from the mechanical model of the MRG/MRE smart isolator agree well with the experimental results indicating that the parameter identification method is feasible and effective.

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Test System ◽  
Output Frequency ◽  
Frequency Effects ◽  
Adult Men ◽  
Frequency Responses ◽  
Significant Difference ◽  
Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

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