检索结果-南通市图书馆

FREE CONVECTION FLOW OF WATER AT 4℃ PASSING AN INFINITE POROUS PLATE WITH CONSTANT SUCTION IN A ROTATING SYSTEM

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 1982年第3期 345-351页

作者： a.raptis,C.Perdikis,G.Tjivanidis University of loannina. School of Physics and Mathematics loannina Greec University of loannina. School of Physics and Mathematics loannina Greec University of loannina. School of Physics and Mathematics loannina Greec

In this work an analysis of steady free convection flow of waterat 4℃ passing a vertical infinite porous plate in a rotating systemis *** solutions for the coupled nonlinear equa-tions are obtained for the velocity and the *** effectof E’(Eckman number) is discussed,when P (Prandtl number)=11.4,which corresponds to water at 4℃.

关键词： PASSING AN INFINITE POROUS PLATE WITH CONSTANT SUCTION IN A ROTATING SYSTEM FREE CONVECTION FLOW OF WATER AT 4 AT

Uses of a dedicated 3D reconstruction software with augmented and mixed reality in planning and performing advanced liver surgery and living donor liver transplantation(with videos)

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2022年第5期21卷 455-461页

作者： Deniz Balci Elvan Onur Kirimker Dimitri Aristotle raptis Yujia Gao Alfred Wei Chieh Kow Department of Surgery Medical Park Goztepe Hastanesi Organ Nakli Merkezi Nisan SokBahce se hir UniversityNo.23 Merdivenkoy KadıkoyIstanbulTurkiye Department of Surgery Ankara UniversityAnkaraTurkiye Clinical Service of HPB Surgery and Liver Transplantation NHS Foundation TrustRoyal Free London HospitalLondonUK Division of Surgery&Interventional Science University College LondonLondonUK Division of Hepatobiliary&Pancreatic Surgery Department of SurgeryNational University of SingaporeSingapore Liver Transplant Program National University Center for Organ Transplantation(NUCOT)National University Health SystemSingapore

The development of digital intelligent diagnostic and treatment technology has opened countless new opportunities for liver surgery from the era of digital anatomy to a new era of digital diagnostics,virtual surgery simulation and using the created scenarios in real-time surgery using mixed *** this article,we described our experience on developing a dedicated 3 dimensional visualization and reconstruction software for surgeons to be used in advanced liver surgery and living donor liver ***,we shared the recent developments in the field by explaining the outreach of the software from virtual reality to augmented reality and mixed reality.

关键词： Living donor liver transplantation 3D reconstruction software 3D volumetry Precision medicine Augmented reality Mixed reality

Height-diameter models for King Boris fir(Abies borisii regis Mattf.) and Scots pine(Pinus sylvestris L.) in Olympus and Pieria Mountains, Greece

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2024年第5期21卷 1475-1490页

作者： Dimitrios I.raptis Dimitra PAPADOPOULOU Angeliki PSARRA Athanasios A.FALLIAS Aristides G.TSITSANIS Vassiliki KAZANA Renewable Natural Resource Management and Bioeconomy Laboratory Department of Forest and Natural Environment SciencesInternational Hellenic University66100 DramaGreece

In forest science and practice, the total tree height is one of the basic morphometric attributes at the tree level and it has been closely linked with important stand attributes. In the current research, sixteen nonlinear functions for height prediction were tested in terms of their fitting ability against samples of Abies borisii regis and Pinus sylvestris trees from mountainous forests in central Greece. The fitting procedure was based on generalized nonlinear weighted regression. At the final stage, a five-quantile nonlinear height-diameter model was developed for both species through a quantile regression approach, to estimate the entire conditional distribution of tree height, enabling the evaluation of the diameter impact at various quantiles and providing a comprehensive understanding of the proposed relationship across the distribution. The results clearly showed that employing the diameter as the sole independent variable, the 3-parameter Hossfeld function and the 2-parameter N?slund function managed to explain approximately 84.0% and 81.7% of the total height variance in the case of King Boris fir and Scots pine species, respectively. Furthermore, the models exhibited low levels of error in both cases(2.310m for the fir and 3.004m for the pine), yielding unbiased predictions for both fir(-0.002m) and pine(-0.004m). Notably, all the required assumptions for homogeneity and normality of the associated residuals were achieved through the weighting procedure, while the quantile regression approach provided additional insights into the height-diameter allometry of the specific species. The proposed models can turn into valuable tools for operational forest management planning, particularly for wood production and conservation of mountainous forest ecosystems.

关键词： Generalized nonlinear weighted regression Monte Carlo cross-validation Mountainous ecosystems Quantile regression Central Greece

MHD Free Convective Flow of Water near 4℃ past a Vertical Moving Plate with Constant Suction

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics 2013年第1期4卷 52-57页

作者： Michalis Xenos Stelios Dimas Andreas raptis Department of Mathematics University of IoanninaIoanninaGreece Instituto de Matematica Estatistica e Computacao CientificaUniversidade Estadual de CampinasCampinasBrasil

The aim of this work is the study of the magnetohydrodynamic (MHD) unsteady free convective flow of water near 4℃ past an infinitely vertical plate moving with constant velocity. The influence of constant uniform suction was also considered. The partial differential equations (PDEs) and their initial and boundary conditions, describing the problem under consideration, are dimensionalized and the numerical solution is obtained by using the finite volume discretization methodology which is suitable for Fluid Mechanics applications. The numerical results for the velocity and temperature fields are shown in figures for different dimensionless parameters entering in the problem under consideration, such as the magnetic parameter, M and the Grashof number, Gr. This study predicts the effects of a constant magnetic field and uniform suction on the free convective flow of water near 4℃, when the water is electrically conductive. Analysis of the results showed that the velocity and temperature profiles are noticeably influenced by these parameters.

关键词： Free Convection Water near 4℃ Constant Magnetic Field Finite Volume Method

Internet Technology in Startup Businesses and Their Contribution to the Development of Entrepreneurship in Greece

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Relations and Diplomacy 2020年第3期8卷 110-119页

作者： Nikolaos raptis Vasiliki Delitheou Charalampos Trasanidis Frederic University Cyprus Nicosia and LimassolCyprus Panteion University of Social and Political Sciences AthensGreece The University of Sheffield South YorkshireEngland

This paper examines the impact of Internet technology on emerging businesses and its contribution to the development of entrepreneurship in *** emphasizes the importance of start-ups in the business ecosystem and the creation of favorable conditions for the development of innovative business *** addition,a theoretical approach of basic concepts of the ecosystem of the startups is carried out which,in combination with the quantitative research that follows,attempts to answer the question whether the development of Internet technology affects entrepreneurship in Greece currently and in the future.

关键词： entrepreneurship innovation Internet startup ecosystem technology

Design and Measurements of Ultra-Wideband Antenna

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Communications, Network and System Sciences 2010年第2期3卷 116-118页

作者： Giorgos TATSIS Vasilis raptis Panos KOSTARAKIS 不详

This paper describes the design, realization and experimental measurements of an antenna element to operate at ultra-wideband (UWB) spectrum. The type of this antenna is a circular disk monopole (CDM), with two notches opposite to each other at two sides of the disk. The feed of the antenna is a coplanar waveguide (CPW). The effect of the presence of the notches is studied through simulations and tested experimentally.

关键词： UWB Antenna CPW CDM

Does recombinant human erythropoietin accelerate correction of post-ulcer-bleeding anaemia?A pilot study

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2004年第4期10卷 586-589页

作者： SpirosD.Ladas DimitriosPolymeros ThomasPagonis KonstantinosTriantafyllou MariaHatziargiriou sotiriosa.raptis Gregorios Paspatis Gastroenterology Unit 2~(nd) Department of Internal MedicineAthens UniversityEvangelismos HospitalAthensGreece Gastroenterology Department Benizelion HospitalHerakleionCreteGreece

AIM:Anaemia caused by acute upper gastrointestinal bleeding is treated with blood transfusion or iron,but patients usually face a two-month recovery period from post- haemorrhage *** prospective,randomised,open, pilot study was designed to investigate whether recombinant human erythropoietin(Epoetin)therapy accelerate haematocrit increase in the post-bleeding recovery period. METHODS:We studied hospitalised patients admitted because of acute ulcer bleeding or haemorrhagic gastritis, who had a haematocrit of 27-33% and did not receive blood *** day after the endoscopic confirmation of cessation of bleeding,they were randomised either to erythropoietin(20 000 IU Epoetin alfa subcutaneously,on days 0,4 and 6)plus iron(100 mg im,on days 1-6,(G_1)or iron only(G_2).Haematocdt was measured on days 0,6,14, 30,45,and 60,respectively. RESULTS:One patient from G_1 and two from G_2 were lost to ***,14 and 13 patients from G_1 and G_2 respectively were *** characteristics,serum iron,ferritin,total iron binding capacity,reticulocytes,and haernatoait were not significantly different at entry to the study. Median reticulocyte counts were significantly different between groups on day six(G_1:4.0,3.0-6.4 vs G_2:3.5,2.1-4.4%, P=0.03)and median haematocrit on day fourteen [G_1:35.9, 30.7-41.0 vs G_2:32.5,29.5-37.0%(median,range),P=0.04]. CONCLUSION:Erythropoietin administration significantly accelerates correction of anemia after acute ulcer bleeding. The haematocrit gain is equivalent to one unit of transfused blood two weeks after the bleeding episode.

关键词： Acute Disease Adult Aged Anemia Erythropoietin, Recombinant dosage Female Follow-Up Studies Gastrointestinal Hemorrhage Humans Male Middle Aged Peptic Ulcer Pilot Projects Prospective Studies Treatment Outcome

Enhanced PAPR in OFDM without Deteriorating BER Performance

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Communications, Network and System Sciences 2011年第3期4卷 164-169页

作者： Spyridon K. Chronopoulos Giorgos Tatsis Vasilis raptis Panos Kostarakis 不详

Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called information subcarrier. OFDM exhibits excellent annotation in channel fades and interferers as only a few subcarriers can be affected and consequently a small part of the original data stream can be lost. Orthogonality between frequencies ensures better spectrum management and obviates the danger of intersymbol interference. However, an essential problem exists. OFDM systems have high peak to average power ratio. This implies large fluctuations in signal power, ending up in increasing complexity of ADCs and DACs. Also, power amplifiers must work in a larger linear dynamic region. In this paper we present two new techniques for reducing Peak to Average Power Ratio (PAPR), that can be added in any OFDM system and we compare them with other existing schemes.

关键词： OFDM Convolutional Encoding QPSK Zero padding IFFT Cyclic Prefix ISI PAPR Soft Reduction μ-Law Algorithm Clipping Ratio (CR) Peak Ratio (PR) BER CCDF μLSR μLaCP

A/D Restrictions (Errors) in Ultra-Wideband Impulse Radios

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Communications, Network and System Sciences 2010年第5期3卷 425-429页

作者： Giorgos Tatsis Constantinos Votis Vasilis raptis Vasilis Christofilakis Panos Kostarakis 不详

Ultra-Wideband Impulse Radio (UWB-IR) technologies, although are relatively easy in transmission but they present difficulties in reception, in fact the reception of such waveform is a quite complicated matter. The main reason is that in fully digital receiver the received waveform must be sampled at a rate of several GHz. This paper focuses on the impact of the Analog to Digital (A/D) conversion stage that is used to sample the received waveform. More specifically we focus on the impact of the two main parameters that affect the performance of the Software Defined Radio (SDR) system. These parameters are the bit resolution and the time jittering. The influence of these parameters is deeply examined.

关键词： UWB Impulse Radio ADC Jitter Error Quantization Error