Community Service Council

It is argued that Article 725 is one of the less obvious but powerful sections of the National Electrical Code. This article covers remote-control, signaling, and power-limited circuits that are not an integral part of a device or appliance. The limitations imposed and the advantages provided by the section are discussed. Application in conjunction with hazardous environments is presented. The installation, application, and transient protection of communications cable for instrumentation circuits is outlined. It is concluded that use of power-limited circuits with intrinsically safe equipment significantly reduces the complexity and cost associated with hazardous environments and inexpensive communication cable can be used for power-limited controls. Direct burial cable makes possible excellent performance and wide bandwidth. Lightning and transient protection can be very effectively implemented. Installation is simple and reliable. >

PreviousNext No AccessSEG Technical Program Expanded Abstracts 1983Role of the alpha‐trimmed mean in combining and analyzing seismic common‐depth‐point gathersAuthors: Terry WattJ. Bee BednarTerry WattCities Service and J. Bee BednarCities Servicehttps://doi.org/10.1190/1.1893840 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Permalink: https://doi.org/10.1190/1.1893840FiguresReferencesRelatedDetailsCited ByOutliers-out stack: a new algorithm for processing seismic data6 December 2018 | Exploration Geophysics, Vol. 49, No. 1Two-dimensional weighted stack determination using signal-to-noise ratios and probability statistics25 October 2014 | Acta Geodaetica et Geophysica, Vol. 49, No. 4Application of alternative seismic-stacking techniques to ringing noise removal from GPR data1 February 2013 | Near Surface Geophysics, Vol. 11, No. 4Enhanced local correlation stacking methodCharlotte Sanchis and Alfred Hanssen12 May 2011 | GEOPHYSICS, Vol. 76, No. 3A SEMBLANCE-GUIDED MEDIAN FILTER1Geophysical Prospecting, Vol. 41, No. 1MODEL-BASED TRANSFORMATIONS OF COMMON MIDPOINT GATHERS1Geophysical Prospecting, Vol. 37, No. 7IMPROVEMENT OF MULTICHANNEL SEISMIC DATA THROUGH APPLICATION OF THE MEDIAN CONCEPT1Geophysical Prospecting, Vol. 37, No. 3LOTEM data processing for areas with high cultural noise levelsPhysics of the Earth and Planetary Interiors, Vol. 53, No. 3-4Seismic Interference, Filtering Methods and Revised Noise Limits SEG Technical Program Expanded Abstracts 1983ISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 1983 Pages: 646 publication data© 1983 Copyright © 1983 Society of Exploration GeophysicistsPublisher:Society of Exploration Geophysicists HistoryPublished: 24 Mar 2005 CITATION INFORMATION Terry Watt and J. Bee Bednar, (1983), "Role of the alpha‐trimmed mean in combining and analyzing seismic common‐depth‐point gathers," SEG Technical Program Expanded Abstracts : 276-277. https://doi.org/10.1190/1.1893840 Plain-Language Summary PDF DownloadLoading ...

Abstract A technique for the continuous representation of dispersion in seismic data was introduced in Robinson (1979). The basic dispersion relation is that derived by Futterman (1962) for an absorption model which is linear with frequency, the so-called "constant Q model." The technique allows one either to remove from, or introduce into, seismic data the effects of dispersion at a constant rate related to some specified absorption quality factor Q.

A new set of multichannel adaptive filtering algorithms containing a feedback convergence function is described. The algorithms represent an extension of the Kalman filtering approach to the linearly constrained multichannel adaptive filtering. In essence, the convergence function in the adaptive filtering algorithm, which is designed to control stability and rate of adaptation, is modified to fashion the Kalman gain structure. Through adaptive feedback schemes, the algorithms are capable of tracking not only the prediction errors with respect to the input multichannel signals, but also the performance errors in the estimated filter weights by means of updating the error covariance matrix. Thus, with double monitoring capability, the revised adaptive filtering algorithm is shown to be more effective in suppressing coherent noises than the previous one, and is well suited for processing the highly time-varying nonstationary data.

The Mesaverde Group (Campanian) in northwestern Colorado is a thick (> 700 m) clastic wedge that prograded eastward into the Western Interior seaway. Models of the main depositional systems in this group were constructed through the study of rock textures and physical and biogenic structures. The geometry of lithofacies was determined from outcrops and End_Page 551------------------------------ analysis of 250 electric logs in the Sand Wash basin. Lithofacies geometry and relations combined with the interpretation of inferred processes from sedimentary structures were used to develop depositional models. The Mesaverde Group can be subdivided into wave-dominated deltaic deposits and their flanking sand-rich strand-plain, interdeltaic deposits. Deltaic headlands were approximately 20 km wide, while the strand plains extended downdrift for at least 60 km. Near deltaic depositional axes, multiple straight and meandering distributaries replace the upper part of the shoreface sequence. Fluvial plain deposits cap this sequence with point-bar sandstones, splays, overbank mudstones, and coals. In interdeltaic areas, progradational shoreface sandstones were deposited and are overlain by coastal plain brackish and freshwater deposits and coals. Marine flooding of the coastal plain was probably due to a combination of subsidence and formation of flanking lows adjacent to depositional axes due to oading. The progradational shoreface is a coarsening-upward sequence 30 to 120 m thick. The sequence includes a basal bioturbated mudstone which becomes interbedded vertically with hummocky cross-stratified sandstones that are capped by an 18 to 60 m thick sandstone. The base of the thick sandstone contains hummocky cross-bedding that grades vertically into troughs that are capped with very low angle cross-bed sets. End_of_Article - Last_Page 552------------

Experimental (clay) and analytical models suggest that regional strain, either extension or compression, significantly affects the fault patterns produced by doming. Our models specifically simulate the shallow deformation produced by gentle doming of a homogeneous material with and without a simultaneously applied, regional horizontal strain. The models of circular domes show that without regional strain, normal faults develop on the crests and flanks. On the flanks, the normal faults have radial trends. With regional extension, normal faults on the crests of circular domes trend perpendicularly to the regional extension direction, whereas many normal faults on the flanks trend obliquely to it. Strike-slip faults trending 60° from the regional extension direction fo m near the peripheries. With regional compression, many normal faults on the crests and flanks of circular domes strike parallel with the regional compression direction. Strike-slip faults trending 30° from the regional compression direction also form on the flanks, and reverse faults striking perpendicularly to the regional compression direction develop on the peripheries. Our models show that regional strain affects the fault patterns produced by elliptical doming similarly. The fault patterns of our models resemble fault patterns of domed strata above salt diapirs and above uplifted blocks of basement.

Conductance measurements for fifteen uni-univalent salts in 2-methylpyridine-N-oxide (2-MPO) were made over the concentration range of 2−120×10−4 mol-dm−3 at 55°C. All conductance data were evaluated by the Lee-Wheaton equation. The results indicate that all of the salts studied are slightly associated in 2-MPO, which is, nevertheless, a reasonably good ionizing solvent compared to other solvents having a similar value for the dielectric constant. The tetraalkylammonium halides are weaker electrolytes than the tetraphenylborate salts in 2-MPO. Ionic limiting molar conductances were obtained by using as a reference electrolyte tris(iso-pentyl)butylammonium tetraphenylborate. Anions appear to be poorly solvated in this solvent but certain cations, particularly Na+ and K+, show evidence of specific ion-solvent interaction.

Twenty-one lithologies have been identified in cores of lowermost Wolfcamp limestone and shale in 6 wells in the general area of World field, Midland basin. These lithologies are summarized into four major lithofacies. (1) One lithofacies is floatstone (greater than 10% clasts larger than 2 mm floating in finer matrix) and variably compacted rudstone (like floatstone, but grain supported) containing angular, lithologically diverse, platform-derived lithoclasts and bioclasts in a clayey or marly matrix. The lithoclasts are a product of disintegration of lithified platform facies, probably Wolfcampian. (2) A second facies is interbedded shale and thin, horizontal, and, in places, ripple-laminated carbonate sands mainly of allochthonous bioclasts. (3) Micritic rudstone and wackestone contain platform-derived micritic intraclasts and bioclasts. This facies is variably porous with intergranular, moldic, solution-enlarged moldic, intragranular, and fracture porosity. (4) Argillaceous packstone and wackestone with allochthonous bioclasts and intraclasts and semi-intraclasts are of off-platform origin. This facies displays a variety of soft sediment deformation features. Facies components probably were supplied and emplaced episodically by a variety of shelf-edge and slope processes during a time of active faulting in the area. Rudite-size clasts were transported 15 mi (22.5 km) or more from the Central Basin platform on the west. Finer detritus swept basinward for much greater distances. Limited comparison is made with carbonate sediments of Exuma Sound, Bahamas. Off-platform Wolfcamp facies abruptly overlie and contrast markedly with a variety of Desmoinesian (Strawn) shallow subtidal platform facies displayed in three cores. The contact, present in one core, is interpreted primarily as a nondepositional disconformity. Age and facies determinations from the cores significantly alter correlations and interpretations made with wireline logs alone, resulting in improved exploration concepts. Allochthonous carbonate complexes may well provide new, potentially important, reservoirs in this region. Preliminary End_Page 242------------------------------ pyrolysis analyses of shaly parts of the debris complexes suggest a good hydrocarbon source potential. End_of_Article - Last_Page 243------------

Coal-related, nitrogen heterocyclic compounds were chromatographed on C18 and cyano function (CN) columns using methanol- and acetonitrile-water mobile phases. Correlation factors were developed to relate retention behavior to structural characteristics such as carbon number, number of double bonds, ring number, and exocyclic aliphatic carbons. Linear regression analysis of the retention data gave an optimum correlation factor that was determined by the number of double bonds plus number of aliphatic carbons plus a correction factor for the nonaromatic rings.