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The 57th Open Seminar on Acoustics OSA'2010 Gliwice, Poland, September 20 - 24, 2010
Archives of Acoustics , 2010, DOI: 10.2478/v10168-010-0036-y
Abstract: This national Seminar, with some foreign guests, in this year is organized by Upper Silesian Division of the Polish Acoustical Society, with cooperation of Institute of Physics - Science-Didactics Center at Silesian University of Technology and Acoustics Committee of Polish Academy of Sciences. In this year OSA'10 will take place in Gliwice at the Congress-Educational Center of the Silesian University of Technology. The conference has two famous honorary patrons - the Magnificence Rector of the Silesian University of Technology, Prof. Andrzej Karbownik, and Ministry of Science and Higher Education, Prof. Barbara Kudrycka. The Seminar is a forum for all fields of acoustics. Particularly in this year, in the Seminar Program you can find the following topics: general acoustics, environmental acoustic, biomedical acoustics, acoustics in blind person's life, active noise control, acoustical emission, vibroacoustics, ultrasound, interior acoustics and others. During the Seminar, the theoretical works, experimental, measuring, technical, applied and normative ones are presented.
Acoustic Emission Monitoring and Microscopic Investigation of Cracks in ERCuNi Cladding
SPLu,OYKwon,KJLee,TBKim,
S.P.Lu
,O.Y.Kwon,K.J.Lee,T.B.Kim

材料科学技术学报 , 2003,
Abstract: A corrosion resistant CuNi cladding was deposited on SM45C (equivalent to AISI1045) substrate by DC inverse arc welding. During the welding process, a three channel acoustic emission (AE) monitoring system was applied to detect the crack signals generating from both the cladding process and after cladding. Characteristics of the welding crack signal and noise signal had been analyzed systematically. Based on the record time of the signal, the solidification crack and delayed crack were distinguished. By two-dimensional AE source location, the crack position was located, and then investigated by scanning electron microscopy (SEM). Results showed that the AE system could detect the welding crack with high sensitivity and the two-dimensional source location could accurately determine the crack position. Microstructures of the cladding and heat affected zone (HAZ) were examined. Dendrites in the cladding and coarse grains in the HAZ were found.
Determining the location of the GeV emission in powerful blazars  [PDF]
Amanda Dotson,Markos Georganopoulos,Demosthenes Kazanas,Eric Perlman
Physics , 2012,
Abstract: An issue currently under debate in the literature is how far from the black hole is the Fermi-observed GeV emission of powerful blazars emitted. Here we present a diagnostic tool for testing whether the GeV emission site is located within the sub-pc broad emission line (BLR) region or further out in the pc scale molecular torus (MT) environment. Within the BLR the scattering takes place at the onset of the Klein-Nishina regime, causing the electron cooling time to become almost energy independent and as a result, the variation of high-energy emission is expected to be achromatic. Contrarily, if the emission site is located outside the BLR, the expected GeV variability is energy-dependent and with amplitude increasing with energy. We demonstrate this using time-dependent numerical simulations of blazar variability and discuss the applicability of our method.
On the location of the gamma-ray emission region for 21 flat spectrum radio quasars with quasi-simultaneous observations  [PDF]
Gang Cao,Jiancheng Wang
Physics , 2013, DOI: 10.1093/mnras/stt1723
Abstract: We try to infer the location of the GeV emission region for 21 flat spectrum radio quasars (FSRQs) with quasi-simultaneous spectral energy distributions (SEDs), in which the SEDs of 21 FSRQs are reproduced by the one-zone leptonic model including the synchrotron-self Compton (SSC) and external Compton (EC) processes. We suggest that the X-ray emission could be produced by the SSC process and the GeV emission could come from the EC process. The EC emission could originate from the inverse Compton (IC) scattering of photons from the broad line region (BLR) and accretion disk or dust torus by the same electron population, which mainly depend on the location of the $\gamma$-ray emission region. We propose a method to constrain the location of the GeV emission region based on the spectral shapes. When the GeV emission is located within the BLR, the IC scattering could occur at the Klein-Nishina regime and produce a broken/steep spectrum in the GeV energy band. When the GeV emission is produced outside the BLR, the IC scattering could take place at the Thomson regime and the GeV spectrum would have the same spectral index as the optical-infrared spectrum. We infer that the location of the GeV emission region is inside the BLR for 5 FSRQs and beyond the BLR for 16 FSRQs. Our results show that the ratio of the magnetic field and electron energy density is close to equipartition condition for 21 FSRQs.
Theory of Acoustic Emission for Micro-Cracks Appeared Under the Surface Layer Machining by Compressed Abrasive  [PDF]
A. K. Aringazin,V. D. Krevchik,V. A. Skryabin,M. B. Semenov,G. V. Tarabrin
Physics , 2007,
Abstract: One of the possible mechanisms for acoustic emission of growing micro-cracks under conditions of the material machining by com-pressed abrasive has been theoretically studied. Physical ground of this mechanism is the dislocation creep in the field of instant contact temperature on stage of micro-cutting with appearance of the wedge-shaped cavity. It has been shown that the energy density for radiated acoustic wave at the moment when the cavity is opened essentially depends on parameters of the material abrasive machining.
The Location of the Nucleus and the Morphology of Emission-Line Regions in NGC 1068  [PDF]
Rodger I. Thompson,Ranga-Ram Chary,Michael R. Corbin,Harland Epps
Physics , 2001, DOI: 10.1086/323637
Abstract: This paper presents NICMOS images of the nucleus and emission line regions in NGC 1068. The location of the nucleus relative to the emission line features is established and the physics underlying the morphology is discussed.
The influence of surface stress on dislocation emission from sharp and blunt cracks in f.c.c. metals  [PDF]
J. Schiotz,A. E. Carlsson
Physics , 1997,
Abstract: We use computer simulations to study the behavior of atomically sharp and blunted cracks in various f.c.c. metals. The simulations use effective medium potentials which contain many-body interactions. We find that when using potentials representing platinum and gold a sharp crack is stable with respect to the emission of a dislocation from the crack tip, whereas for all other metals studied the sharp crack is unstable. This result cannot be explained by existing criteria for the intrinsic ductile/brittle behavior of crack tips, but is probably caused by surface stresses. When the crack is no longer atomically sharp dislocation emission becomes easier in all the studied metals. The effect is relatively strong; the critical stress intensity factor for emission to occur is reduced by up to 20%. This behavior appears to be caused by the surface stress near the crack tip. The surface stress is a consequence of the many-body nature of the interatomic interactions. The enhanced dislocation emission can cause an order-of-magnitude increase in the fracture toughness of certain materials, in which a sharp crack would propagate by cleavage. Collisions with already existing dislocations will blunt the crack, if this prevents further propagation of the crack the toughness of the material is dramatically increased.
A Role of Chaotic Phenomenon and the Central Place System in a Firm’s Location Selections  [PDF]
Toshiharu Ishikawa
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.21019
Abstract: When a manufacturing firm has a plan to build a factory, the determination of the factory’s location site is one of the most important elements in the plan. Since the manufacturer does not have enough information of economic conditions of all potential location sites, the manufacturer cannot determine immediately its location site. A series of steps are taken to determine the location place. The firm makes range of searching area small step by step toward the site deter-mination; 1) Determination of a prospective region in a large space, 2) Selection of a potential area in that region, 3) Choice of an urban district in that area, 4) Decision of a site in the district. This paper proposes that chaotic phenome-non, which is appeared in the calculation processes to specify the optimal location site, may be used to identify a pro-spective region. And then, it is shown in the paper that the central place systems laid in the region play a role in the se-lection of a potential area for the factory location. This paper elucidates how a firm searches step by step an appropriate factory’s location within a large geographical area.
Intelligent location of simultaneously active acoustic emission sources: Part I  [PDF]
T. Kosel,I. Grabec
Computer Science , 2007,
Abstract: The intelligent acoustic emission locator is described in Part I, while Part II discusses blind source separation, time delay estimation and location of two simultaneously active continuous acoustic emission sources. The location of acoustic emission on complicated aircraft frame structures is a difficult problem of non-destructive testing. This article describes an intelligent acoustic emission source locator. The intelligent locator comprises a sensor antenna and a general regression neural network, which solves the location problem based on learning from examples. Locator performance was tested on different test specimens. Tests have shown that the accuracy of location depends on sound velocity and attenuation in the specimen, the dimensions of the tested area, and the properties of stored data. The location accuracy achieved by the intelligent locator is comparable to that obtained by the conventional triangulation method, while the applicability of the intelligent locator is more general since analysis of sonic ray paths is avoided. This is a promising method for non-destructive testing of aircraft frame structures by the acoustic emission method.
Intelligent location of simultaneously active acoustic emission sources: Part II  [PDF]
T. Kosel,I. Grabec
Computer Science , 2007,
Abstract: Part I describes an intelligent acoustic emission locator, while Part II discusses blind source separation, time delay estimation and location of two continuous acoustic emission sources. Acoustic emission (AE) analysis is used for characterization and location of developing defects in materials. AE sources often generate a mixture of various statistically independent signals. A difficult problem of AE analysis is separation and characterization of signal components when the signals from various sources and the mode of mixing are unknown. Recently, blind source separation (BSS) by independent component analysis (ICA) has been used to solve these problems. The purpose of this paper is to demonstrate the applicability of ICA to locate two independent simultaneously active acoustic emission sources on an aluminum band specimen. The method is promising for non-destructive testing of aircraft frame structures by acoustic emission analysis.
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