Author
Geoffrey A. Clark
Other affiliations: Lawrence Livermore National Laboratory
Bio: Geoffrey A. Clark is an academic researcher from Arizona State University. The author has contributed to research in topics: Upper Paleolithic & Mesolithic. The author has an hindex of 33, co-authored 124 publications receiving 3562 citations. Previous affiliations of Geoffrey A. Clark include Lawrence Livermore National Laboratory.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, a block adaptive filtering procedure is proposed in which the filter coefficients are adjusted once per each output block in accordance with a generalized least mean-square (LMS) algorithm.
Abstract: Block digital filtering involves the calculation of a block or finite set of filter outputs from a block of input values This paper presents a block adaptive filtering procedure in which the filter coefficients are adjusted once per each output block in accordance with a generalized least mean-square (LMS) algorithm Analyses of convergence properties and computational complexity show that the block adaptive filter permits fast implementations while maintaining performance equivalent to that of the widely used LMS adaptive filter
303 citations
TL;DR: In this paper, the authors describe structures spatiales de foyers, cendres, concentrations d'os and d'artefacts at the site du Paleolithique moyen de Kebara, Israel.
Abstract: Resultats des fouilles recentes (1982-90) sur le site du Paleolithique moyen de Kebara, Israel. Synthese de la stratigraphie complexe du site et datation. Description des structures spatiales de foyers, cendres, concentrations d'os et d'artefacts. Resultats des etudes mineralogiques des sediments afin de determiner si la distribution spatiale des ossements animaux est le resultat d'activites humaines (charognage) ou de processus post-depositionnels. Synthese sur l'outillage lithique mousterien axee sur la technologie de production et les chaines operatoires. Analyse taphonomique des mammiferes, en particulier des ongules. Inventaire des restes humains du Paleolithique moyen et etude de la sepulture intentionnelle d'homme adulte
257 citations
TL;DR: A block adaptive filtering procedure in which the filter coefficients are adjusted once per each output block in accordance with a generalized least mean-square (LMS) algorithm shows that it permits fast implementations while maintaining performance equivalent to that of the widely used LMS adaptive filter.
Abstract: Block digital filtering involves the calculation of a block or finite set of filter outputs from a block of input values. This paper presents a block adaptive filtering procedure in which the filter coefficients are adjusted once per each output block in accordance with a generalized least mean-square (LMS) algorithm. Analyses of convergence properties and computational complexity show that the block adaptive filter permits fast implementations while maintaining performance equivalent to that of the widely used LMS adaptive filter.
206 citations
TL;DR: In this article, specific implementations of the finite impulse response (FIR) block adaptive filter in the frequency domain are presented and some of their important properties are discussed, and the time-domain block adaptive filtering is shown to be equivalent to the frequency-domain adaptive filtering, provided data sectioning is done properly.
Abstract: Specific implementations of the finite impulse response (FIR) block adaptive filter in the frequency domain are presented and some of their important properties are discussed. The time-domain block adaptive filter implemented in the frequency domain is shown to be equivalent to the frequency-domain adaptive filter (derived in the frequency domain), provided data sectioning is done properly. All of the known time- and frequency-domain adaptive filters [1]-[12], [16]-[18] are contained in the set of possible block adaptive filter structures. Thus, the block adaptive filter is generic and its formulation unifies the current theory of time- and frequency-domain FIR adaptive filter structures. A detailed analysis of overlap-save and overlap-add implementations shows that the former is to be preferred for adaptive applications because it requires less computation, a fact that is not true for fixed coefficient filters.
197 citations
TL;DR: In this article, evidence for purposeful disposal of the dead and other inferences of ritual behavior in the Middle Paleolithic are examined geoarchaeologically, and logical incongruencies are identified between the published observations and the conclusion that Neandertals were being buried by their conspecifics.
Abstract: Evidence for purposeful disposal of the dead and other inferences of ritual behavior in the Middle Paleolithic are examined geoarchaeologically. Cave geomorphology, sedimentology, and taphonomy form the basis for a reexamination of the Neandertal discoveries most often cited in this connection: La Chapelle-auxSaints, Le Moustier, La Ferrassie, Teshik-Tash, Regourdou, and Shanidar. Logical incongruencies are identified between the published observations and the conclusion that Neandertals were being buried by their conspecifics.
178 citations
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More filters
2,839 citations
01 Aug 1997
TL;DR: This paper provides a comprehensive and detailed treatment of different beam-forming schemes, adaptive algorithms to adjust the required weighting on antennas, direction-of-arrival estimation methods-including their performance comparison-and effects of errors on the performance of an array system, as well as schemes to alleviate them.
Abstract: Array processing involves manipulation of signals induced on various antenna elements. Its capabilities of steering nulls to reduce cochannel interferences and pointing independent beams toward various mobiles, as well as its ability to provide estimates of directions of radiating sources, make it attractive to a mobile communications system designer. Array processing is expected to play an important role in fulfilling the increased demands of various mobile communications services. Part I of this paper showed how an array could be utilized in different configurations to improve the performance of mobile communications systems, with references to various studies where feasibility of apt array system for mobile communications is considered. This paper provides a comprehensive and detailed treatment of different beam-forming schemes, adaptive algorithms to adjust the required weighting on antennas, direction-of-arrival estimation methods-including their performance comparison-and effects of errors on the performance of an array system, as well as schemes to alleviate them. This paper brings together almost all aspects of array signal processing.
2,169 citations
TL;DR: The African Middle and early Late Pleistocene hominid fossil record is fairly continuous and in it can be recognized a number of probably distinct species that provide plausible ancestors for H. sapiens, and suggests a gradual assembling of the package of modern human behaviors in Africa, and its later export to other regions of the Old World.
2,165 citations
Book•
31 May 1997
TL;DR: Adaptive Filtering: Algorithms and Practical Implementation may be used as the principle text for courses on the subject, and serves as an excellent reference for professional engineers and researchers in the field.
Abstract: From the Publisher:
Adaptive Filtering: Algorithms and Practical Implementation is a concise presentation of adaptive filtering, covering as many algorithms as possible while avoiding adapting notations and derivations related to the different algorithms. Furthermore, the book points out the algorithms which really work in a finite-precision implementation, and provides easy access to the working algorithms for the practicing engineer. Adaptive Filtering: Algorithms and Practical Implementation may be used as the principle text for courses on the subject, and serves as an excellent reference for professional engineers and researchers in the field.
1,294 citations
TL;DR: An overview is presented of several frequency-domain adaptive filters that efficiently process discrete-time signals using block and multirate filtering techniques, including convergence properties and computational complexities of the adaptive algorithms and the effects of circular convolution and aliasing on the converged filter coefficients.
Abstract: An overview is presented of several frequency-domain adaptive filters that efficiently process discrete-time signals using block and multirate filtering techniques. These algorithms implement a linear convolution that is equivalent to a block time-domain adaptive filter, or they generate a circular convolution that is an approximation. Both approaches exploit the computational advantages of the FFT. Subband adaptive filtering is also briefly described. Here the input data are first processed by a bank of narrowband bandpass filters that are approximately nonoverlapping. The transformed signals are then decimated by a factor that depends on the degree of aliasing that can be tolerated, resulting in a large computational savings. Several performance issues are considered, including convergence properties and computational complexities of the adaptive algorithms and the effects of circular convolution and aliasing on the converged filter coefficients. >
908 citations