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Acoustic Emission (AE) signals, which are electrical version of acoustic emissions, are usually analysed using a set of signal
parameters. The major objective of signal analysis is to study the characteristics of the sources of emissions. Peak amplitude(P
a
) and rise time(R
t
) are two such parameters used for source characterization. In this paper, we theoretically investigate the efficiency ofP
a
andR
t
to classify and characterize AE sources by modelling the input stress pulse and transducer. Analytical expressions obtained
forP
a
andR
t
clearly indicate their use and efficiency for source characterization. It is believed that these results may be of use to
investigators in areas like control systems and signal processing also 相似文献
4.
Acoustic emission technique for leak detection in an end shield of a pressurised heavy water reactor
P. Kalyanasundaram T. Jayakumar B. Raj C.R.L. Murthy A. Krishnan 《Nuclear Engineering and Design》1989,116(2)
This paper discusses the successful application of the Acoustic Emission Technique (AET) for detection and location of leak paths present on the inaccessible side of an end shield of a Pressurised Heavy Water Reactor (PHWR). The methodology was based on the fact that air and water leak AE signals have different characteristic features. Baseline data was generated from a sound end-shield of a PHWR for characterizing the background noise. A mock up end-shield system with saw cut leak paths was used to verify the validity of the methodology. It was found that air leak signals under pressurisation (as low as 3 psi) could be detected by frequency domain analysis. Signals due to air leaks from various locations of a defective end-shield were acquired and analysed. It was possible to detect and locate leak paths. Presence of detected leak paths were further confirmed by alternate test. 相似文献
5.
Real-time implementation of an order-statistic filter (OSF) or ranked order filter requires the computation of the order statistic (ranked order) of the samples in a window which gets periodically updated with the arrival of a new sample(s). The authors give an algorithm for the computation of the running order statistic. A highly parallel architecture suitable for VLSI implementation is presented. The architecture is very versatile, with programmable window size and rank order. An expansion algorithm and its VLSI architecture, which permit the usage of two r -bit OSFs to implement an (r +1)-bit OSF, where r is the resolution of the input signal samples, are given. In a special case where one is satisfied with at most one LSB error, the hardware complexity of the proposed architecture can be reduced by almost one half. It is further shown how a VLSI chip incorporating the proposed architecture can be used as the basic building block in the real-time implementation of other forms of nonlinear filters 相似文献
6.
The broadband integrated services digital networks (B-ISDN) based on asynchronous transfer mode (ATM) technology can support
a wide range of applications such as voice, video, still images, and data. Compression techniques increase the effective bandwidth
utilization, but the bursty and asynchronous nature of the traffic can still lead to congestion in the network, and degradation
of image quality and quality of service (QOS). Some of the features to provide better coding schemes for ATM networks are
layered coding, resynchronization, buffering, interleaved schemes, constrained bit rate due to buffers, encapsulation with
the RTP or AAL1 for clock recovery, lapped transforms, motion compensation, and optimal bit allocation for coders based on
wavelet transforms. We review various techniques forimage and video coding such as transforms, motion compensation, vector
quantization, and subband coding. We outline the impact of the cell loss ratio (CLR), delay and cell delay variation (CDV)
on video coding: blocking effects, loss of frame synchronization, motion vectors, and vector quantization codewords. The open
problems include tuning coding parameters to the available QOS provided by the network. 相似文献
7.
V Chandrasekaran Ch Sreerama Murthy P Subrahmaniam G Venkateswarlu 《Bulletin of Materials Science》1986,8(1):39-48
Iron-chromium-cobalt alloys possess attractive magnetic properties combined with good formability and hence are identified as technologically important magnetic materials. Alloys with compositions Fe-28·9 Cr-15·6 Co and Fe-28·4 Cr-20·1Co (weight percent) have been studied. Heat-treatment parameters during thermomagnetic treatment viz temperature, time and external magnetic field were optimized with reference to magnetic properties. The fully treated anisotropic alloys develop remanence=11·5–12·0 kilo Gauss, coercivity=600–650 Oersted and energy product=4–4·5 million Gauss Oersted. Electron microscopic and Mössbauer spectroscopic techniques were used to identify the original and transformed phases. During the various stages of the development of the alloy, the changes in mechanical hardness were correlated with magnetic hardness. 相似文献
8.
Diels-alder adducts from safflower oil fatty acids: I. Maleic anhydride as dienophile 总被引:1,自引:0,他引:1
G. S. R. Sastry B. G. K. Murthy J. S. Aggarwal 《Journal of the American Oil Chemists' Society》1971,48(11):686-688
The Diels-Alder reaction between alkali conjugated and elaidinized safflower oil fatty acids and maleic anhydride was studied
under various experimental conditions. The principal product which was obtained in 51–55% yields was a mixture of the adduct
of maleic anhydride and maleic acid in 40∶60 proportions. The isolation and properties of this mixed adducts from the reaction
mixture and their conversion to trimethyl, tributyl and triallyl esters are described. The trimethyl ester was also obtained
in good yield from the methyl esters of the fatty acids and dimethyl maleate. 相似文献
9.
G. S. R. Sastry B. G. K. Murthy J. S. Aggarwal 《Journal of the American Oil Chemists' Society》1972,49(3):192-195
The Diels-Alder adducts from alkali conjugated and elaidinized safflower fatty acids with acrylic, methacrylic, crotonic and
cinnamic acids and their esters as dienophiles were obtained in 40–64% yields. Low yields of 16–18% were obtained when 10-undecenoic
acid and its ester were used. Most of the adducts could be estimated quantitatively in the reaction products by column chromatography
or gas liquid chromatography (GLC). For the estimation of the adducts from crotonic and 10-undecenoic acids a combination
of column chromatography and GLC techniques was employed. Partitioning between hexane and 90% methanol, partial esterification
with alkali washing, and splitting and fractional distillation under reduced pressure were methods used to obtain the adducts
in 90–95% purity. 相似文献
10.
Dhiraj Murthy Alexander Gross Alexander Pensavalle 《Journal of Computer-Mediated Communication》2016,21(1):33-49
This article explores intersections between place, race/ethnicity, and gender amongst American Twitter users and makes an argument that studying the intensity of tweets provides insights into how and why particular groups tweet. Given recent events in American political life such as the shooting in Ferguson, Missouri and the reactions by young, urban African Americans on Twitter, understanding the role of race, place, gender, and age is important. We observed the time between tweets of urban American Twitter users and explored whether the medium may be providing traditionally marginalized groups, such as young Black men, with potential avenues for mobilizing communication and access to resources. 相似文献