scholarly journals A case study of seismograph self-noise test from Trillium 120QA seismometer and Reftek 130 data logger

2019 ◽  
Vol 23 (6) ◽  
pp. 1347-1355
Author(s):  
Weiwei Xu ◽  
Songyong Yuan
Keyword(s):  
Frequency Band ◽  
Low Noise ◽  
The Self ◽  
Force Balance ◽  
Site Location ◽  
Data Logger ◽  
Noise Estimate ◽  
Alignment Correction ◽  
Correlation Analysis Method ◽  
Noise Test

Abstract Seismograph self-noise has become a de facto standard for instrument comparisons and their performance assessment and is considered as one of the most vital parameters for instrument comparison. For self-noise testing of modern force-balance feedback broadband seismometers, several factors have been thoroughly discussed and thought to be attributable to the self-noise estimate, including the data selection criteria, sensor alignment correction, timing error, correlation analysis method, and computational parameter selection during the computational process. This study focuses on some other factors, such as local site conditions, temperature insulating methods, and data logger self-noise interferences, with an aim to differentiate the self-noise contribution of these sources and their dependencies on time and frequency. A series of experiments were conducted at the Beijing National Earth Observatory using a Trillium 120QA seismometer and Reftek-130 data acquisition system at three different locations ranging from the ordinary equipment warehouse to global seismographic network level cave with a hard-rock base. Results show that noise-free site is necessary for the self-noise test in a frequency band greater than approximately 0.1 Hz. However, for a frequency band less than 0.1 Hz, the insulation method and installation procedures are far more important, although the influence of the site location cannot be neglected fully. A suitable preamp should be selected in the data logger configurations to ensure that the low-noise amplitude of the sensor signal is above the digitizer noise level.

scholarly journals A preliminary survey of the broadband seismic wavefield at Puu Oo, the active vent of Kilauea volcano, Hawaii

1996 ◽  
Vol 39 (2) ◽  
Author(s):  
D. Seidl ◽  
M. Hellweg ◽  
P. Okubo ◽  
H. Rademacher
Keyword(s):  
Frequency Band ◽  
Power Spectra ◽  
Volcanic Tremor ◽  
Digital Data ◽  
Periodic Pattern ◽  
Data Logger ◽  
Remarkable Feature ◽  
Wide Range ◽  
Active Vent ◽  
Seismic Wavefield

The seismic wavefield near an active volcanic vent consists of superimposed signals in a wide range of frequency bands from sources inside and outside the volcano. To characterize the broadband wavefield near Puu Oo, we deployed a profile of three three-component broadband sensors in a 200 m long line about 1.5 km WSW of the active vent. During this period, Puu Oo maintained a constant, but very low level of activity. The digital data logger recorded the wavefield continuously in the frequency band between 0.01 and 40 Hz between June 25 and July 9, 1994. At the same time, local wind conditions along with air temperature and pressure were monitored by a portable digital weather station. On the basis of characteristic elements, such as waveform, spatial coherence between stations, particle motion and power spectra, the wavefield can be divided into three bands. The dominant signals in the frequency band between 0.01 and 0.1 Hz are not coherent among the stations. Their ground velocities correlate with the wind speed. The signals in the 0.1 to 0.5 Hz band are coherent across the profile and most probably represent a superposition of volcanic tremor and microseisms from the Pacific Ocean. Much of the energy above 0.5 Hz can be attributed to activity at the vent. Power spectra from recordings of the transverse components show complex peaks between 0.5 and 3 Hz which vary in amplitude due to site effects and distance. On the other hand, power spectra calculated from the radial components show a clearly periodic pattern of peaks at 1 Hz intervals for some time segments. A further remarkable feature of the power spectra is that they are highly stationary.

scholarly journals Inertial Vibration Characteristics of Track Chassis Caused by Reciprocating Motion of Crank Slider

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Zhong Tang ◽  
Yu Li ◽  
Yuepeng Zhou ◽  
Haotian Zhang
Keyword(s):  
Excitation Frequency ◽  
Vertical Vibration ◽  
Vibration Characteristics ◽  
The Self ◽  
Force Balance ◽  
Inertia Force ◽  
Natural Mode ◽  
Reciprocating Motion ◽  
Measuring Point ◽  
Track Beam

The crank slider of self-propelled baling machinery is used for straw compression on the crawler chassis structure. During the reciprocating motion of the crank slider, the inertia of the piston will cause a greater shock to baling machinery. In this paper, the inertia of the crank slider piston was analyzed on crawler chassis. The model and parameter values of the inertia force balance of the crank slider were established by the complete balance method. The test mode was used to analyze the natural mode and mode shape of the piston. The vertical vibration amplitudes of the crawler chassis beam were tested and used to reflect the specific inertial vibration characteristics of the self-propelled baling machinery caused by the reciprocating motion of the piston. The inertial vibration caused by the reciprocating motion of the crank slider was eliminated by the method of weighting the tail of the track beam. Results indicated that the self-balancing counterweight of the crank slider was 261.82 kg. The six natural modal frequencies of the piston were 4.62, 17.26, 29.82, 63.85, 83.73, and 141.58 Hz, respectively. During the reciprocating motion of the piston, the first-order frequency of the piston would be excited by feeding auger excitation frequency of 3.77 Hz and may cause resonance. And, the vertical vibrates of track beam was based on the measuring point 6 as a fulcrum. Adding a counterweight of 265 kg at the end of the track chassis would completely eliminate the self-propelled baling machinery inertial vibration caused by the reciprocating motion of the crank slider.

scholarly journals Hubungan Konsep Diri Akademik dengan Motivasi Berprestasi pada Remaja Awal yang Tinggal di Panti Asuhan di Denpasar

2014 ◽  
Vol 1 (2) ◽  
Author(s):  
Komang Diah Laxmy Prabadewi ◽  
Putu Nugrahaeni Widiasavitri
Keyword(s):  
Achievement Motivation ◽  
Quantitative Research ◽  
Early Adolescents ◽  
Simple Random Sampling ◽  
The Self ◽  
Self Concept ◽  
Moderate Intensity ◽  
P Value ◽  
Quantitative Research Methods ◽  
Correlation Analysis Method

  Early adolescence is a period for self-concept formation. The self concept is a set of beliefs and feelings of the individual about their own, including physical characteristics, social, emotional, aspiration and achievement (Hurlock, 1999). Concerned with the need of achievement, adolescents need to develop their self-concept specially their academic self-concept as a particular provision in order to face a competition in the work world later. The self concept is not an innate factor, but it is learned and shaped by individual experience in dealing with others. That is equal with the academic self-concept. When a person living in a different situation with the general one, such as live in an orphanage, it can affect early adolescents in shaping their self-concept, at last it can affect their desire to achieve their achievement. According to these conditions, the researchers wanted to see whether there are relationships between academic self-concept and achievement motivation in early adolescents who lives in an orphanage. This study uses quantitative research methods which is correlation analysis method using product moment that involving 120 early adolescents orphanages as subjects that obtained by using sample taking technique simple random sampling . The result found in this research, there is a positive and significant relationship between academic self-concept and achievement motivation in early adolescents who lives in orphanages in Denpasar, which is indicated by the correlation coefficient (r) between the variables of self-concept and achievement motivation is 0.588 with p value 0.000 (p< 0.05), which means that the variable of academic self-concept and achievement motivation variables correlated significantly and positively and both of those are at moderate intensity   Keywords: self concept, academic self-concept, achievement motivation, orphanages, early adolescents

Low noise amplifier for 180 GHz frequency band

2008 ◽  
Author(s):  
Pekka Kangaslahti ◽  
David Pukala ◽  
Todd Gaier ◽  
William Deal ◽  
Xiaobing Mei ◽  
...  
Keyword(s):  
Frequency Band ◽  
Low Noise ◽  
Low Noise Amplifier ◽  
Noise Amplifier

Design of a Two Stage Low Noise System in the Frequency Band 1.8 2.2GHz

2014 ◽  
Author(s):  
Xiaorong Zhao ◽  
Honghui Fan ◽  
Feiyue Ye ◽  
Xiufang Qian ◽  
Dan Chen ◽  
...  
Keyword(s):  
Frequency Band ◽  
Low Noise ◽  
Two Stage

Design of a Two Stage Low Noise System in the Frequency Band 1.8-2.2GHz for Wireless System

2015 ◽  
Vol 8 (3) ◽  
pp. 111-122 ◽  
Author(s):  
Xiaorong Zhao ◽  
Honghui Fan ◽  
Feiyue Ye ◽  
Xiufang Qian ◽  
Dan Chen ◽  
...  
Keyword(s):  
Frequency Band ◽  
Low Noise ◽  
Wireless System ◽  
Two Stage

A Theoretical Model for the Self-Noise of a Velocity-Broadband Seismometer

2021 ◽  
Author(s):  
Zhan Lin ◽  
Bing Xue ◽  
Xinxin Ma ◽  
Hongyuan Wang ◽  
Lijuan Li
Keyword(s):  
Theoretical Model ◽  
Frequency Band ◽  
Feedback Loop ◽  
Noise Source ◽  
Feedback System ◽  
The Self ◽  
Noise Sources ◽  
Broadband Seismometer ◽  
Forward Path ◽  
Feedback Seismometer

ABSTRACT A theoretical model of the seismometer self-noise can be used to predict the self-noise. Its inputs are mechanical and electrical parameters of the seismometer. In this article, we studied the theoretical model of the self-noise of the velocity-broadband seismometer, using the CS60 seismometer as an example. Velocity-broadband seismometer is a type of feedback seismometer. The previous theoretical model of the self-noise of the feedback seismometer only involved noise sources in the forward path of the feedback system. Our model involved not only noise sources in the forward path, but also noise sources in the feedback path and external to the feedback loop. We introduced noise sources in the feedback system of the seismometer and the method of calculating their levels with mechanical and electrical parameters, developed expressions for referring all noise sources to the input terminal of the feedback system, and finally established the model. We compared the CS60 seismometer’s predicted self-noise calculated using this model with the measured self-noise, and we found good agreement between them. The contribution of each noise source to the total noise was studied, and it was found that the dominant noise source in CS60 is different over different frequency bands. Over the frequency band below 0.0095 Hz, the noise of the integrator (in the feedback path) is the dominant noise source. Over the frequency band from 0.0095 to 0.21 Hz, suspension noise is the dominant noise source. Over the frequency band from 0.21 to 39 Hz, the noise of the differential driver (external to the feedback loop) is the dominant noise source. Over the frequency band above 39 Hz, the noise of the preamplifier (in the forward path) is the dominant noise source. In addition, some viewpoints about the low-noise design of seismometers were proposed.

Sign in / Sign up

Export Citation Format

Share Document