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排序方式: 共有225条查询结果,搜索用时 15 毫秒
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2.
Admission control mechanism and performance analysis based on stochastic automata networks formalism
Lynda MokdadAuthor Vitae 《Journal of Parallel and Distributed Computing》2011,71(4):594-602
IEEE 802.16 has been designed to support QoS (Quality of Service) in Wireless broadband Metropolitan Networks (WMAN), and specifically in the access networks. To achieve this, the IEEE 802.16.e amendment introduces the service differentiation by five service classes (UGS, ertPS, rtPS, nrtPS and BE). To maintain the QoS of active connections and to avoid any congestion in the network, an Admission Control (AC) is defined. AC aims to accept or reject a new connection according to the negotiated parameters and the availability of resources in the network. This mechanism is not standardized and let to the operators. We tackle this point, by proposing in this study a new Admission Control (AC) that improves the QoS of BE traffic by avoiding a strict bandwidth assignment of other traffics (rtPS and nrtPS) as is defined in major previous studies. The proposed mechanism is based on token bucket for rtPS, nrtPS and BE traffics in order to reduce lightly the number of accepted connections and to improve considerably the number of accepted BE connections. To evaluate the performance of the proposed scheme, we use PEPS (Performance Evaluation of Parallel Systems) which is a powerful tool based on models which can be described with Stochastic Automata Networks (SAN). PEPS can solve complex models with a large state space and with many synchronized events. Therefore, we show that this tool is suitable for wireless network, and specifically for the proposed scheme, toward numerical results we show as we expected that our proposed AC outperform the classical one by reducing lightly the performance of other service classes. 相似文献
3.
We demonstrate a method to fabricate a high-aspect ratio metal tip attached to microfabricated cantilevers with controlled angle, length, and radius, for use in electrostatic force microscopy. A metal wire, after gluing it into a guiding slot that is cut into the cantilever, is shaped into a long, thin tip using a focused ion beam. The high-aspect ratio results in considerable reduction of the capacitive force between tip body and sample when compared to a metal coated pyramidal tip. 相似文献
4.
Taft Casey T.; Pless Anica P.; Stalans Loretta J.; Koenen Karestan C.; King Lynda A.; King Daniel W. 《Canadian Metallurgical Quarterly》2005,73(1):151
In this study, the authors identified potential risk factors for partner violence perpetration among a subsample (n=109) of men who participated in a national study of Vietnam veterans. Partner violent (PV) men with posttraumatic stress disorder (PTSD) were compared with PV men without PTSD and nonviolent men with PTSD on family-of-origin variables, psychiatric problems, relationship problems, and war-zone factors. PV men with PTSD were the highest of the 3 groups on every risk factor other than childhood abuse. Group contrasts and a classification tree analysis suggest some potential markers and mechanisms for the association between PTSD and partner violence among military veterans and highlight the need for theory development in this area of inquiry. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Kate Sanders Sally Fincher Dennis Bouvier Gary Lewandowski Briana Morrison Laurie Murphy Marian Petre Brad Richards Josh Tenenberg Lynda Thomas Richard Anderson Ruth Anderson Sue Fitzgerald Alicia Gutschow Susan Haller Raymond Lister Renée McCauley John McTaggart Christine Prasad Terry Scott Dermot Shinners-Kennedy Suzanne Westbrook Carol Zander 《Expert Systems》2005,22(3):121-128
Abstract: This paper presents a case study of the use of a repeated single‐criterion card sort with an unusually large, diverse participant group. The study, whose goal was to elicit novice programmers' knowledge of programming concepts, involved over 20 researchers from four continents and 276 participants drawn from 20 different institutions. In this paper we present the design of the study and the unexpected result that there were few discernible systematic differences in the population. The study was one of the activities of the National Science Foundation funded Bootstrapping Research in Computer Science Education project (2003). 相似文献
6.
King Lynda A.; King Daniel W.; Fairbank John A.; Keane Terence M.; Adams Gary A. 《Canadian Metallurgical Quarterly》1998,74(2):420
Structural equation modeling procedures were used to examine relationships among several war zone stressor dimensions, resilience-recovery factors, and post-traumatic stress disorder symptoms in a national sample of 1,632 Vietnam veterans (26% women and 74% men). A 9-factor measurement model was specified on a mixed-gender subsample of the data and then replicated on separate subsamples of female and male veterans. For both genders, the structural models supported strong mediation effects for the intrapersonal resource characteristic of hardiness, postwar structural and functional social support, and additional negative life events in the postwar period. Support for moderator effects or buffering in terms of interactions between war zone stressor level and resilience–recovery factors was minimal. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Canonical processes of semantically annotated media production 总被引:1,自引:1,他引:0
Lynda Hardman Željko Obrenović Frank Nack Brigitte Kerhervé Kurt Piersol 《Multimedia Systems》2008,14(6):327-340
8.
Curt L. Elderkin Lynda D. Corkum Claudia Bustos Erica L. Cunningham David J. Berg 《Journal of Great Lakes research》2012
Burrowing mayfly species of the genus Hexagenia are well known indicators of environmental health in lakes and rivers. Two species, H. limbata and H. rigida, are indistinguishable as nymphs and as adult females. Our objectives were to develop a genetic technique to distinguish between the two species and identify morphological features that separate cryptic nymphs and adult females. Fifty nymphs were collected before emergence from 10 sites throughout the western basin of Lake Erie in 2004 and 2005. Using known specimens of adult aerial male H. limbata and H. rigida, we used the mitochondrial cytochrome c oxidase subunit 1 (COI) gene to identify a 16 base pair (bp) difference between species. DNA sequencing confirmed correct species identification based on differences in abdominal pigmentation patterns on adult female imagos in 19 of 20 cases; the lone exception was a female with very faint pigmentation. Pigmentation patterns between species were consistent on nymphs, subimagos and imagos of both sexes. Populations of both species are panmictic across the western basin of Lake Erie, but H. limbata is the numerically dominant species, representing 70 to 100% of nymphs at sites in both years. A separate lineage of H limbata was discovered in the samples. The ability to distinguish nymphs of the two species will aid in developing more sensitive ecosystem indicators. 相似文献
9.
Doll Lynda S.; O'Malley Paul M.; Pershing Alan L.; Darrow William W.; Hessol Nancy A.; Lifson Alan R. 《Canadian Metallurgical Quarterly》1990,9(3):253
Evaluated the effectiveness of human immunodeficiency virus (HIV) testing and counseling among homosexual and bisexual men participating in the San Francisco City Clinic Cohort (Centers for Disease Control, 1987). Behavioral data from 181 men who learned their HIV antibody status between 1985 and 1987 were compared with data from 128 men who were tested but declined to receive their results. Significant declines in risk indices for unprotected receptive and insertive anal intercourse occurred between 1983–1984 and 1986–1987, but these declines were independent of both knowledge of HIV status and actual serostatus. Ss who chose to learn their HIV status were no more likely to report depression or anxiety subsequent to testing. Frequent access to and discussion of risk-reduction information may be important motivators of behavioral change. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Lynda Zaidi Stéphane Bruzaud Alain Bourmaud Pascal Médéric Mustapha Kaci Yves Grohens 《应用聚合物科学杂志》2010,116(3):1357-1365
Melt‐state and solid state mechanical properties and thermal stability of polylactide layered silicate nanocomposites elaborated by melt intercalation were studied as a function of clay content. Wide angle X‐ray scattering results, transmission electron microscopy observations, and rheological measurements indicated that the clay was finely distributed in the polylactide matrix. Contrary to nonlinear mechanical properties, thermal and linear mechanical properties were shown to increase with increasing clay fraction. The nanoindentation measurements confirm the significant increase of linear mechanical properties previously observed by tensile tests. The good correlation of linear mechanical properties at the macrometric and nanometric scales is explained by the high dispersion degree of the nanofiller in the biodegradable polymer matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献