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.

Toward Developing a Conceptual Framework to explain Positive Thinking Based on Islamic View

2016 ◽  
Vol 2 ◽  
Author(s):  
Mohammad Kodayarifard ◽  
Bagher GhobariBonab ◽  
Saeed Akbari ZardKhaneh ◽  
Enayatollah Zamanpour ◽  
Saeid Zandi ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Cultural Values ◽  
Attachment Theory ◽  
Relational Theory ◽  
The Self ◽  
Automatic Thoughts ◽  
Thinking Styles ◽  
Positive Thinking ◽  
Future Expectations ◽  
Islamic View

The aim of the present study was to critically review theories and approaches related to positive thinking and to develop a theoretical model based on Islamic view, which is compatible with cultural values in Iran. To fulfill the stated aim, philosophical and historical foundations of positive thinking in different schools of thought including Leibnitz, Sadra, Kant, Freud and James were critically reviewed. In addition, the theoretical constructs associated with positive thinking including hope, positive automatic thoughts and paradigms of Seligman, Scheier and Carver in this regard were critically studied. Finally, based on the attachment theory of Bowlby, positive thinking was established on and its applications were explained for individuals' thinking styles about past events, present interpretations of events and future expectations. Since the attachment theory is a relational theory, positive thinking in this paradigm was discussed in a way that included individuals' relationship with transcendental being, others, nature, and the self.

Noise source location and scaling of subsonic upper-surface blowing

2020 ◽  
Vol 19 (3-5) ◽  
pp. 191-206
Author(s):  
Trae L Jennette ◽  
Krish K Ahuja
Keyword(s):  
Strouhal Number ◽  
Noise Source ◽  
Low Frequency ◽  
Directivity Pattern ◽  
Source Location ◽  
Dipole Source ◽  
Frequency Noise ◽  
Noise Sources ◽  
Trailing Edge ◽  
Trailing Edge Noise

This paper deals with the topic of upper surface blowing noise. Using a model-scale rectangular nozzle of an aspect ratio of 10 and a sharp trailing edge, detailed noise contours were acquired with and without a subsonic jet blowing over a flat surface to determine the noise source location as a function of frequency. Additionally, velocity scaling of the upper surface blowing noise was carried out. It was found that the upper surface blowing increases the noise significantly. This is a result of both the trailing edge noise and turbulence downstream of the trailing edge, referred to as wake noise in the paper. It was found that low-frequency noise with a peak Strouhal number of 0.02 originates from the trailing edge whereas the high-frequency noise with the peak in the vicinity of Strouhal number of 0.2 originates near the nozzle exit. Low frequency (low Strouhal number) follows a velocity scaling corresponding to a dipole source where as the high Strouhal numbers as quadrupole sources. The culmination of these two effects is a cardioid-shaped directivity pattern. On the shielded side, the most dominant noise sources were at the trailing edge and in the near wake. The trailing edge mounting geometry also created anomalous acoustic diffraction indicating that not only is the geometry of the edge itself important, but also all geometry near the trailing edge.

scholarly journals Innovative techniques for the improvement of industrial noise sources identification by beamforming

Noise Mapping ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 129-137
Author(s):  
Giorgio Baldinelli ◽  
Francesco Bianchi ◽  
Danilo Costarelli ◽  
Francesco D’Alessandro ◽  
Flavio Scrucca ◽  
...  
Keyword(s):  
Image Processing ◽  
Noise Source ◽  
Focal Length ◽  
Noise Sources ◽  
Geometric Information ◽  
Industrial Noise ◽  
Sources Identification ◽  
Innovative Technique ◽  
Innovative Techniques

Abstract An innovative technique based on beamforming is implemented, at the aim of detecting the distances from the observer and the relative positions among the noise sources themselves in multisource noise scenarios. By means of preliminary activities to assess the optical camera focal length and stereoscopic measurements followed by image processing, the geometric information in the source-microphone direction is retrieved, a parameter generally missed in classic beamforming applications. A corollary of the method consists of the possibility of obtaining also the distance among different noise sources which could be present in a multisource environment. A loss of precision is found when the effect of the high acoustic reflectivity ground interferes with the noise source.

scholarly journals Uncertainty Avoidance as a Moderating Factor to the Self-Congruity Concept: The Development of a Conceptual Framework

SAGE Open ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 215824402110018
Author(s):  
Shaohua Yang ◽  
Salmi Mohd Isa ◽  
T. Ramayah
Keyword(s):  
Theoretical Model ◽  
Conceptual Framework ◽  
Significant Contribution ◽  
Integrated Model ◽  
Uncertainty Avoidance ◽  
The Self ◽  
Destination Marketing ◽  
Tourism Research ◽  
Revisit Intention ◽  
Conceptual Paper

The aim of this article was to propose a framework based on the theory of self-congruity and on Hofstede’s uncertainty avoidance. The framework was to combine destination personality, self-congruity, uncertainty avoidance, and tourists’ revisit intention. The present conceptual paper proposed an integrated model of self-congruity which incorporates the effect of uncertainty avoidance. More importantly, the uncertainty avoidance was introduced as a moderator between self-congruity and revisit intention. Based on the theoretical framework proposed in this article, the estimated results affirmed the applicability of the theory of self-congruity for tourism research. Moreover, by extending the theoretical model through the incorporation of a variable of uncertainty avoidance in the context of tourism, this article offers a significant contribution to the tourism literature. It is important to understand how the theory of self-congruity applies across a broad cultural spectrum. This article also offers several implications for destination marketing organizations from a practical perspective.

scholarly journals Statistical analysis of Stromboli VLP tremor in the band [0.1–0.5] Hz: some consequences for vibrating structures

2006 ◽  
Vol 13 (4) ◽  
pp. 393-400 ◽  
Author(s):  
E. De Lauro ◽  
S. De Martino ◽  
M. Falanga ◽  
M. Palo
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Noise Source ◽  
Volcanic Tremor ◽  
Large Data ◽  
Musical Instruments ◽  
Data Set ◽  
Long Period ◽  
Vibrating Structures ◽  
Analyze Time Series

Abstract. We analyze time series of Strombolian volcanic tremor, focusing our attention on the frequency band [0.1–0.5] Hz (very long period (VLP) tremor). Although this frequency band is largely affected by noise, we evidence two significant components by using Independent Component Analysis with the frequencies, respectively, of ~0.2 and ~0.4 Hz. We show that these components display wavefield features similar to those of the high frequency Strombolian signals (>0.5 Hz). In fact, they are radially polarised and located within the crater area. This characterization is lost when an enhancement of energy appears. In this case, the presence of microseismic noise becomes relevant. Investigating the entire large data set available, we determine how microseismic noise influences the signals. We ascribe the microseismic noise source to Scirocco wind. Moreover, our analysis allows one to evidence that the Strombolian conduit vibrates like the asymmetric cavity associated with musical instruments generating self-sustained tones.

scholarly journals Modeling and Mapping of Combined Noise Annoyance for Aircraft and Road Traffic Based on a Partial Loudness Model

2021 ◽  
Vol 18 (16) ◽  
pp. 8724
Author(s):  
Wonhee Lee ◽  
Chanil Chun ◽  
Dongwook Kim ◽  
Soogab Lee
Keyword(s):  
Background Noise ◽  
Road Traffic ◽  
Noise Source ◽  
Transportation Systems ◽  
Masking Effect ◽  
Noise Sources ◽  
Noise Annoyance ◽  
Short And Long Term ◽  
Loudness Model

Complex transportation systems often produce combined exposure to aircraft and road noise. Depending on the noise source, the annoyance response is different, and a masking effect occurs between the noise sources within the combined noise. Considering these characteristics, partial loudness was adopted to evaluate noise annoyance. First, a partial loudness model incorporating binaural inhibition was proposed and validated. Second, short- and long-term annoyance models were developed using partial loudness. Finally, the annoyance of combined noise was visualized as a map. These models can evaluate the annoyance by considering both the intensity and frequency characteristics of the noise. In addition, it is possible to quantify the masking effect that occurs between noise sources. Combined noise annoyance maps depict the degree of annoyance of residents and show the background noise effect, which is not seen on general noise maps.

A Method for Noise Source Levels Inversion with Underwater Ambient Noise Generated by Typhoon in Deep Ocean

2018 ◽  
Vol 26 (02) ◽  
pp. 1850007 ◽  
Author(s):  
Qiulong Yang ◽  
Kunde Yang ◽  
Shunli Duan
Keyword(s):  
Ambient Noise ◽  
Noise Source ◽  
Surface Wind ◽  
Deep Ocean ◽  
Noise Sources ◽  
Noise Field ◽  
Sea Surface Wind ◽  
Source Level ◽  
The Western Pacific ◽  
Good Agreement

Sea-surface wind agitation can be considered the dominant noise sources whose intensity relies on local wind speed during typhoon period. Noise source levels in previous researches may be unappreciated for all oceanic regions and should be corrected for modeling typhoon-generated ambient noise fields in deep ocean. This work describes the inversion of wind-driven noise source level based on a noise field model and experimental measurements, and the verification of the inverted noise source levels with experimental results during typhoon period. A method based on ray approach is presented for modeling underwater ambient noise fields generated by typhoons in deep ocean. Besides, acoustic field reciprocity is utilized to decrease the calculation amount in modeling ambient noise field. What is more, the depth dependence and the vertical directionality of noise field based on the modeling method and the Holland typhoon model are evaluated and analyzed in deep ocean. Furthermore, typhoons named “Soulik” in 2013 and “Nida” in 2016 passed by the receivers deployed in the western Pacific (WP) and the South China Sea (SCS). Variations in sound speed profile, bathymetry, and the related oceanic meteorological parameters are analyzed and taken into consideration for modeling noise field. Boundary constraint simulated annealing (SA) method is utilized to invert the three parameters of noise source levels and to minimize the objective function value. The prediction results with the inverted noise source levels exhibit good agreement with the measured experiment data and are compared with predicted results with other noise sources levels derived in previous researches.

scholarly journals Source Contribution Analysis for Exterior Noise of a High-Speed Train: Experiments and Simulations

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Jie Zhang ◽  
Xinbiao Xiao ◽  
Dewei Wang ◽  
Yan Yang ◽  
Jing Fan
Keyword(s):  
High Speed ◽  
Noise Source ◽  
High Speed Train ◽  
Noise Sources ◽  
Sound Sources ◽  
Lower Region ◽  
Source Contribution ◽  
Array Measurements ◽  
Noise Characteristics ◽  
Train Speed

This paper presents a detailed investigation into the contributions of different sound sources to the exterior noise of a high-speed train both experimentally and by simulations. The in situ exterior noise measurements of the high-speed train, including pass-by noise and noise source identification, are carried out on a viaduct. Pass-by noise characteristics, noise source localizations, noise source contributions of different regions, and noise source vertical distributions are considered in the data analysis, and it is shown how they are affected by the train speed. An exterior noise simulation model of the high-speed train is established based on the method of ray acoustics, and the inputs come from the array measurements. The predicted results are generally in good agreement with the measurements. The results show that for the high-speed train investigated in this paper, the sources with the highest levels are located at bogie and pantograph regions. The contributions of the noise sources in the carbody region on the pass-by noise increase with an increasing distance, while those in the bogie and train head decrease. The source contribution rates of the bogie and the lower region decrease with increasing train speed, while those of the coach centre increase. At a distance of 25 m, the effect of the different sound sources control on the pass-by noise is analysed, namely, the lower region, bogie, coach centre, roof region, and pantograph. This study can provide a basis for exterior noise control of high-speed trains.

A micromechanistic model of the combustion synthesis process: Part II. Numerical simulation

1994 ◽  
Vol 9 (10) ◽  
pp. 2605-2619 ◽  
Author(s):  
Yangsheng Zhang ◽  
Gregory C. Stangle
Keyword(s):  
Theoretical Model ◽  
Combustion Synthesis ◽  
Quantitative Description ◽  
Computer Experiments ◽  
The Self ◽  
Synthesis Process ◽  
Energy Redistribution ◽  
Precise Control ◽  
Physical And Chemical ◽  
Proper Balance

A series of computer experiments was conducted for the self-propagating combustion synthesis process in the Nb-C system, based on the general theoretical model that was developed previously.1 A detailed and quantitative description was given for the various physical and chemical processes that take place during the combustion synthesis process. The results are presented at various length scales in order to provide an insight into understanding the mechanisms that are responsible for the self-propagating behavior. It was shown that a fundamental understanding and precise control of the process require a strong emphasis on the joint contributions of the rates of the various mass and energy redistribution processes that occur during the combustion synthesis process. A proper balance of each of the elementary process rates must be achieved to give rise to self-propagating behavior. This paper illustrates some of the capabilities of the general theoretical model in quantitatively describing the self-propagating combustion synthesis process.

Identification of Noise Source Based on Partial Coherence Analysis

2012 ◽  
Vol 239-240 ◽  
pp. 482-486
Author(s):  
Hai Ping Wu ◽  
Jing Jun Lou ◽  
Wen Wu Liu
Keyword(s):  
Analytic Hierarchy Process ◽  
Source Identification ◽  
Noise Source ◽  
Partial Coherence ◽  
Coherence Analysis ◽  
Noise Sources ◽  
Analytic Hierarchy ◽  
Noise Source Identification ◽  
Source Excitation ◽  
Hierarchy Process

Noise source identification is the precondition and foundation of the noise reduction. There are some limitations while using some common method to analyze noise sources, so on the basis of partial coherence analysis and analytic hierarchy process, a method was proposed which can sort noise source contribution. When noise in the multi-source excitation system is coherent，this method can identify and sort noise source.

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