检索结果-南通市图书馆

Random and Periodic sleep schedules for Target Detection in sensor networks

在线全文

学校读者我要写书评

暂无评论

Journal of Computer science & Technology 2008年第3期23卷 343-354页

作者： Vaishali P.sadaphal Bijendra n.Jain Tata Research Development and Design Centre(TRDDC) PuneIndia Department of Computer science and Engineering Indian Institute of TechnologyDelhiNew DelhiIndia

We study random and periodic sleep schedules from the point of view of delay in detecting the target. We consider sleep schedules in which a sensor in ＂inactive＂ mode wakes up either randomly or periodically to detect presence of the target within its vicinity resulting into two sleep schedules：（a） random wake-up schedule, and （b） periodic wake-up schedule respectively. specifically, we analyse and obtain for the random wake-up schedule the expected delay in detection, and the delay, such that with probability P, the delay is less than the computed value. For the periodic wake-up schedule we show that there exists an upper bound on the delay. Further we compute the average value of delay. We have shown that the theoretically computed averages and the upper bounds on the delay match with the simulation results for the random wake-up and periodic wake-up schedules.

关键词： sleep schedule energy conservation target detection

Experimental investigations of internal energy dissipation during fracture of fiber-reinforced ultra-high-performance concrete

在线全文

学校读者我要写书评

暂无评论

Frontiers of structural and Civil Engineering 2019年第1期13卷 190-200页

作者： Eric n.lAnDIs Roman KRAVchUK Dmitry lOsHKOV Department of Civil &Environmental Engineering University of MaineOronoME 04469USA

split-cylinder fracture of fiber-reinforced ultra-high-performance concrete (UHPC)was examined using two complementary techniques:X-ray computed tomography (CT)and acoustic emission (AE).Fifty-mm-diameter specimens of two different fiber types were scanned both before and after load *** the CT images,fiber orientation was evaluated to establish optimum and pessimum specimen orientations,at which fibers would have maximum and minimum effect,*** expected,fiber orientation affected both the peak load and the toughness of the specimen,with the optimum toughness being between 20% and 30%higher than the *** AE energy was also affected *** CT scans of the specimens were used to measure internal damage. Damage was quantified in terms of internal energy dissipation due to both matrix cracking and fiber pullout by using calibration measurements for *** results showed that fiber pullout was the dominant energy dissipation mechanism;however,the sum of the internal energy dissipation measured amounted to only 60% of the total energy dissipated by the specimens as measured by the net work of *** is postulated that localized compaction of the UHPC matrix as well as internal friction between fractured fragments makes up the balance of internal energy dissipation.

关键词： ultra-high-performance concrete concrete fracture X-ray computed tomography acoustic emission

Evolution of Cervical lesions Associated with Human Papillomavirus Infection after the Introduction of Vaccination

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Obstetrics and Gynecology 2023年第8期13卷 1307-1323页

作者： Montserrat de la Torre Ana María Colino lone nielsen Alejandro Pascual Concepción Millana María Jesús González Patricia Barreiro Eva Rodríguez Dolores García Aranzazu Gómez Rosa Rodero María Jesús Fernández Department of surgical Pathology Hospital Clínico San Carlos Madrid Spain Department of surgical Pathology Hospital Universitario del Sureste Madrid Spain Grupo de Investigación en Anatomía Patológica Hospital Clínico San Carlos Instituto de Investigación Sanitaria Hospital Clínico San Carlos Madrid Spain Department of legal Medicine Psychiatry and Surgical Pathology Complutense University of Madrid Madrid Spain

Background: The main objective of this study is to analyse the change in the type of lesions developed by HPV-infected patients after the introduction of the vaccine in three different periods;2002-2006 (years previous to the implementation of the vaccine in spain), 2009-2011 (shortly after the vaccination) and 2020-2021 (years where the vaccine was well established) at a single hospital. Methods: This is an observational, descriptive, retrospective study based on the review of the results of the biopsies of patients with HPV lesions at a single large tertiary hospital, Hospital Clínico san Carlos, in Madrid, spain. We have collected the data from three different time periods: 2002-2006, 2009-2011, 2020-2021 to try to understand the potential changes in these lesions after vaccine introduction. Results: In this time we have reviewed the data from 946 women. In these three periods, a decreasing trend in the rate of squamous cell carcinoma was noted, the rate of adenocarcinoma remains stable, and the rate of cervical intraepithelial neoplasia grades 2 - 3 (CIn 2-3) lesions shows an increasing trend. We have also found a change in the mean ages of the patients with these lesions, as this increased in the three lesions caused by HPV after the implementation of the vaccine. Our study indicates that the identification of other high risk serotypes, apart from 16 and 18, as well as those with indeterminate risk, has undergone a progressive increase, increasing from 24.24% and 14.11% respectively in 2002-2006 to 40.42% and 28.34% in 2020-2021. Conclusion: Our study confirms the effectiveness of the vaccines developed so far, against the HPV serotypes they contain. This is demonstrated by the evidence, in our population, of a decrease in the incidence of squamous cell carcinoma in uterine cervix. In parallel, an increase in the mean age of diagnosis has been verified, for both squamous cell carcinoma and its CIn 2-3 precursor lesions, as well as a change in the infective tren

关键词： HPV serotypes Cervix Vaccine CIn 2 - 3 squamous Cell Carcinoma Women’s Health

A comprehensive review of significant researches on content based indexing and retrieval of visual information

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Computer science 2013年第5期7卷 782-799页

作者： R. PRIYA T. n. sHAnMUGAM Department of Mathematics Anna University-Chennai Chennai 600 025 India

Developments in multimedia technologies have paved way for the storage of huge collections of video doc- uments on computer systems. It is essential to design tools for content-based access to the documents, so as to allow an efficient exploitation of these collections. Content based anal- ysis provides a flexible and powerful way to access video data when compared with the other traditional video analysis tech- niques. The area of content based video indexing and retrieval （CBVIR）, focusing on automating the indexing, retrieval and management of video, has attracted extensive research in the last decade. CBVIR is a lively area of research with endur- ing acknowledgments from several domains. Herein a vital assessment of contemporary researches associated with the content-based indexing and retrieval of visual information. In this paper, we present an extensive review of significant researches on CBV1R. Concise description of content based video analysis along with the techniques associated with the content based video indexing and retrieval is presented.

关键词： nultimedia information content based video retrieval (CBVR) content based video indexing and retrieval (CBVIR) shot segmentation object segmentation feature extraction indexing motion estimation querying key frame retrieval and indexing.

Historical fluxes of metal and metalloids in an aquatic ecosystem affected by land-use change and mining activities in northwestern Mexico

在线全文

学校读者我要写书评

暂无评论

International Journal of sediment Research 2023年第5期38卷 724-738页

作者： Ochoa-Contreras Roberto Jara-Marini Martín Enrique Ruiz-Fernández Ana Carolina sanchez-Cabeza Joan Albert Meza-Figueroa Diana Pérez-Bernal libia Hascibe Posgrado en Ciencias Centro de Investigación en Alimentación y Desarrollo Unidad Hermosillo 2. Centro de Investigación en Alimentación y Desarrollo Unidad Hermosillo Unidad Acad emica Mazatlán Instituto de Ciencias del Mar y Limnología Universidad Nacional Autónoma de M exico Departamento de Geología División de Ciencias Exactas y Naturales Universidad de Sonora Rosales y Encinas

Freshwater reservoirs are essential owing because of their ecological, economic, and social *** are particularly vulnerable to contamination, as of metal and metalloids, derived from anthropogenic activities like mining. The temporal variations in trace element concentrations(arsenic(As),mercury(Hg), chromium(Cr), copper(Cu), nickel(ni), lead(Pb), and zinc(Zn)), enrichment, fluxes, and possible sources were evaluated by studying two sediment cores from the la Angostura(AnG) Reservoir(northwest Mexico), using210Pb geochronology. The enrichment factors showed from null to minor enrichment for most elements, but moderate to severe enrichment of mercury(Hg). Most trace element concentrations had a detrital origin, and notable Hg concentration increases since the past decade were associated with severe drought periods, likely resulting from wildfires. The observed sediment concentrations of As and Hg can cause adverse effects on biota in the ecosystem since they are above the probable effect level(PEl). Development of strategies for metal attenuation in this reservoir is recommended and metals should be controlled until specific ecotoxicological studies are performed.

关键词： Aquatic ecosystems ~(210)Pb geochronology Mining activities Metals Metalloids Enrichment factors

Black holes in asymptotic safety with higher derivatives:accretion and stability analysis

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

chinese Physics C 2021年第7期45卷 293-304页

作者： Fabian H.Zuluaga luis A.sanchez Escuela de Fisica Universidad Nacional de ColombiaA.A.3840MedellinColombia

We review steady spherically symmetric accretion onto a renormalization group improved schwarzschild space-time,which is a solution to an asymptotically safe theory(As)containing high-derivative *** use a Hamiltonian dynamical system approach for the analysis of the accretion of four types of isothermal test fluids:ultra-stiff fluid,ultra-relativistic fluid,radiation fluid,and sub-relativistic *** important outcome of our study is that,contrary to the claim in a recent work,there are physical solutions for the accretion of an ultra-relativistic fluid in As,which include subsonic,supersonic,and transonic ***,we study quantum corrections to the known stability of the accretion in general relativity(GR).To this end,we use a perturbative procedure based on the continuity equation with the mass accretion rate being the perturbed *** classes of perturbations are studied:standing and traveling *** find that quantum gravity effects either enhance or diminish the stability of the accretion depending on the type of test fluid and the radial distance to the central object.

关键词： asymptotic safety black holes accretion stability

Inertial confinement fusion and prospects for power production

在线全文

学校读者我要写书评

暂无评论

High Power laser science and Engineering 2015年第1期3卷 36-43页

作者： C.B.Edwards C.n.Danson HiPER Project STFC Rutherford Appleton Laboratory AWE plc

As our understanding of the environmental impact of fossil fuel based energy production increases, it is becoming clear that the world needs a new energy solution to meet the challenges of the future. A transformation is required in the energy market to meet the need for low carbon, sustainable, affordable generation matched with security of supply. In the short term, an increasing contribution from renewable sources may provide a solution in some locations. In the longer term,low carbon, sustainable solutions must be developed to meet base load energy demand, if the world is to avoid an ever increasing energy gap and the attendant political instabilities. laser-driven inertial fusion energy(IFE) may offer such a solution.

关键词： ICF IFE inertial confinement fusion inertial fusion energy

The impact of anti-epidemic measures against coronavirus disease 2019 (COVID-19) on the seasonal influenza epidemic

在线全文

学校读者我要写书评

暂无评论

chinese Medical Journal 2021年第7期134卷 879-880页

作者： Tatyana n.Ilyicheva Vadim nGureyev Vector state Research Center of Virology and Biotechnology Koltsovo 630559Russia Department of natural sciences Novosibirsk State UniversityNovosibirsk 630090Russia.

To the Editor:A new type of coronavirus—severe acute respiratory syndrome coronavirus 2 causing coronavirus disease 2019(COVID-19)emerged in 2019.[1]On March 11,2020,World Health Organization(WHO)Director-General declared that the outbreak can be characterized as a pandemic.[2]According to the WHO,[3]on March 18,2020,the number of laboratory-confirmed cases of COVID-19 was over 200 thousands *** some countries,unprecedented anti-epidemic measures have been carried out to stop the spread of infection.

关键词： epidemic acute measures

Application of ^(14)n(d,α)^(12)C nuclear Reaction to the Concentration Analysis of nitrogen in Iron Meteorites

在线全文

学校读者我要写书评

暂无评论

chinese Physics letters 1995年第5期12卷 265-268页

作者： HU Beilai A.l.Hanson K.W.Jones Department of Physics Nankai UniversityTianjin 300071 Brookhaven national laboratory UptonNew York 11973U.S.A.

The ^(14)n(d,α)^(12)C nuclear reaction has been used to measure the nitrogen content in iron *** analysis was made with 2.0MeV^(2)H^(+) beam from Brookhaven 3.5MV research electrostatic *** detection limits of about ... 详细信息

关键词： electrostatic beam