Littérature scientifique sur le sujet « HTC computation »
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Articles de revues sur le sujet "HTC computation"
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Shen, Fan, Siyuan Rong, Naigang Cui et Xianren Kong. « A tensor-based modelling and simulation method for multibody system ». Engineering Computations 34, no 4 (12 juin 2017) : 1107–25. http://dx.doi.org/10.1108/ec-11-2015-0375.
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Purpose The purpose of this paper is to provide a method with convenient modelling as well as precise computation to the research of complex multi-body system, such as robot arms and solar power satellite. Classical modelling method does not always fit these two requirements. Design/methodology/approach In this paper, tensor coordinates (TC) and homogeneous tensor coordinates (HTC) method with gradient components are developed, which also have a convenient interface with classical theory. Findings The HTC proved its precision and effectiveness by two examples. In HTC model, equations have a more convenient form as matrix and the results coincide well with classical one. Research limitations/implications There is no plenty detailed operations supported in mathematics yet, which may be developed in further research. Practical implications With TC/HTC method, the research work can be separated more thoroughly: a simpler modelling work is left to scientists, when more computing work is handed to the computers. It may ease scientists’ brains in multibody modelling. Originality/value The HTC method has the advantages of absolute nodal coordinate formulations, tensor and homogeneous coordinate (HC) and it may be used in multibody mechanics, or other related engineerings.
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Chabicovsky, Martin, Petr Kotrbacek, Hana Bellerova, Jan Kominek et Miroslav Raudensky. « Spray Cooling Heat Transfer above Leidenfrost Temperature ». Metals 10, no 9 (21 septembre 2020) : 1270. http://dx.doi.org/10.3390/met10091270.
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This study considers spray cooling starting at surface temperatures of about 1200 °C and finishing at the Leidenfrost temperature. Cooling is in the film boiling regime. The paper uses experimental techniques for the study of which spray parameters are necessary for good prediction of spray cooling intensity. The research is based on experiments with water and air-mist nozzles. The following spray parameters were measured together with a heat transfer coefficient: water flowrate, water impingement density, impact pressure, droplet size and velocity. Derived parameters as droplet kinetic energy, droplet momentum and droplet Reynolds number are used in the tested correlations as well. Ten combinations of spray parameters used for correlation functions for the heat transfer coefficient (HTC) are studied and discussed. Correlation functions for prediction of HTC are presented and it is shown which spray parameters are necessary for reliable computation of HTC. The best results were obtained when the parameters impact pressure and water impingement density were used together. It was proven that the correlations based only on water impingement density, which are the most frequent in literature, can not provide reliable results.
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El-Sayed, Hesham, Sharmi Sankar, Heng Yu et Gokulnath Thandavarayan. « Benchmarking of Recommendation Trust Computation for Trust/Trustworthiness Estimation in HDNs ». International Journal of Computers Communications & ; Control 12, no 5 (10 septembre 2017) : 612. http://dx.doi.org/10.15837/ijccc.2017.5.2895.
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In the recent years, Heterogeneous Distributed Networks (HDNs) is a predominant technology implemented to enable various application in different fields like transportation, medicine, war zone, etc. Due to its arbitrary self-organizing nature and temporary topologies in the spatial-temporal region, distributed systems are vulnerable with a few security issues and demands high security countermeasures. Unlike other static networks, the unique characteristics of HDNs demands cutting edge security policies. Numerous cryptographic techniques have been proposed by different researchers to address the security issues in HDNs. These techniques utilize too many resources, resulting in higher network overheads. This being classified under light weight security scheme, the Trust Management System (TMS) tends to be one of the most promising technology, featured with more efficiency in terms of availability, scalability and simplicity. It advocates both the node level validation and data level verification enhancing trust between the attributes. Further, it thwarts a wide range of security attacks by incorporating various statistical techniques and integrated security services. In this paper, we present a literature survey on different TMS that highlights reliable techniques adapted across the entire HDNs. We then comprehensively study the existing distributed trust computations and benchmark them in accordance to their effectiveness. Further, performance analysis is applied on the existing computation techniques and the benchmarked outcome delivered by Recommendation Trust Computations (RTC) is discussed. A Receiver Operating Characteristics (ROC) curve illustrates better accuracy for Recommendation Trust Computations (RTC), in comparison with Direct Trust Computations (DTC) and Hybrid Trust Computations (HTC). Finally, we propose the future directions for research and highlight reliable techniques to build an efficient TMS in HDNs.
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Tran, Duc Q., Vaughn Barry, Ana G. Antun, Maria Ribeiro, Sidney F. Stein et Christine L. Kempton. « Numeracy in Patients with Hemophilia ». Blood 126, no 23 (3 décembre 2015) : 40. http://dx.doi.org/10.1182/blood.v126.23.40.40.
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Abstract Background: Numeracy, defined as the ability to handle basic probability and numerical concepts including computation, estimation, logic, and problem solving, is an under-recognized component of health literacy. Numeracy has been shown to influence performance of health tasks in non-hemophilia populations. Little is known about numeracy in the hemophilia population. Since hemophilia treatment requires understanding of numerical concepts to manage factor replacement, it is likely that numeracy also influences performance of health tasks by patients with hemophilia. A greater understanding of numeracy status and the characteristics influencing numeracy in the hemophilia population may allow healthcare providers to better influence health task performance. The objective of this study is to explore numeracy in the hemophilia population using two different tests of numeracy and to evaluate characteristics that are associated with low numeracy. Methods: Using a cross-sectional design, adults with moderate or severe hemophilia A or B who spoke and read English were enrolled at their annual visit at the Emory/Children's Health Care of Atlanta Hemophilia Treatment Center (HTC). Numeracy was measured using the validated Schwartz Woloshin (SW) test requiring answers in words and the unvalidated stick figure test requiring answers using images. Subjects were considered numerate with the SW numeracy test if all three questions were answered correctly or with the stick figure numeracy test if all four questions were answered correctly. Demographic and socioeconomic characteristics collected included age, race, ethnicity, household income (more or less than $50,000), level of education completed (more or less than completion of college), and duration of time followed at this HTC. Clinical information including type and severity of hemophilia, history of viral infections, history of depression, and use of chronic medication were abstracted from the medical records. Descriptive statistics of each variable and bivariate associations between numerate status and each dependent variable were calculated. Multivariable modeling using logistic regression was performed using the validated SW numeracy test as the dependent variable. Results: Of 91 enrolled participants with complete data, all were men. Most had hemophilia A [n=82 (90%)] and severe disease [69 (76%)]. Median age was 34 years [interquartile range (IQR) 18]. Sixty-three (69%) were Caucasian; 5 (6%) were Hispanic; 55 (61%) reported income of <$50,000; 33 (36%) had received an undergraduate degree or higher. Median duration of time followed at the HTC was 17.0 years [IQR 18]. Twenty-four (26%) were HIV positive; 54 (59%) were HCV positive; and 19 (21%) had history of depression. Forty-one (45%) used at least one chronic medication other than factor replacement. Using the SW numeracy test, there were 22 (24%) participants who were numerate. Using the stick figure numeracy test, 60 (66%) were numerate. Only 20 (22%) of all the participants answered all seven questions correctly; two participants (2%) were numerate on the SW test but not on the stick figure test; 40 participants (44%) were numerate on the stick figure numeracy test but not on the SW test; 29 (32%) were not numerate on either test. On bivariable analysis, SW numeracy was associated with higher education (p<0.01), higher income (p=0.035), and the use of chronic medication (p=0.048). On multivariable analysis, after adjusting for age, race, and ethnicity, SW numeracy was associated with higher education (OR 6.21, 95% CI = 1.95-19.76), use of chronic medication (OR 4.31, 95% CI = 1.29-14.34), and less time followed at the HTC (OR 0.92, 95% CI = 0.86-0.97). Conclusion: Among patients with hemophilia, a significant proportion of patients were not numerate. Patients with less than a college education were more likely to not be numerate. Accordingly, many patients with less than a college education may struggle to understand basic numeracy concepts and this may influence their understanding of dosing, factor pharmacokinetics and probability. The impact of numeracy on health outcomes and the utility of the SW and stick figure numeracy tests to help guide patient-centered discussions that involve mathematical concepts are important areas of future research. Disclosures Tran: Novo Nordisk: Honoraria. Kempton:Baxter Biopharmaceuticals: Honoraria; Biogen Idec: Honoraria; Kedrion Biopharma: Honoraria; CSL Behring: Honoraria.
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Cui, Zhe, Shivalik Sen, Sriram Karthik Badam et Niklas Elmqvist. « VisHive : Supporting web-based visualization through ad hoc computational clusters of mobile devices ». Information Visualization 18, no 2 (23 janvier 2018) : 195–210. http://dx.doi.org/10.1177/1473871617752910.
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Current web-based visualizations are designed for single computers and cannot make use of additional devices on the client side, even if today’s users often have access to several, such as a tablet, a smartphone, and a smartwatch. We present a framework for ad hoc computational clusters that leverage these local devices for visualization computations. Furthermore, we present an instantiating JavaScript toolkit called VisHive for constructing web-based visualization applications that can transparently connect multiple devices—called cells—into such ad hoc clusters—called a hive—for local computation. Hives are formed either using a matchmaking service or through manual configuration. Cells are organized into a master–slave architecture, where the master provides the visual interface to the user and controls the slaves and the slaves perform computation. VisHive is built entirely using current web technologies, runs in the native browser of each cell, and requires no specific software to be downloaded on the involved devices. We demonstrate VisHive using four distributed examples: a text analytics visualization, a database query for exploratory visualization, a density-based spatial clustering of applications with noise clustering running on multiple nodes, and a principal component analysis implementation.
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Puzyrkov, Dmitry, Sergey Polyakov, Viktoriia Podryga et Sergey Markizov. « Concept of a Cloud Service for Data Preparation and Computational Control on Custom HPC Systems in Application to Molecular Dynamics ». EPJ Web of Conferences 173 (2018) : 05014. http://dx.doi.org/10.1051/epjconf/201817305014.
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At the present stage of computer technology development it is possible to study the properties and processes in complex systems at molecular and even atomic levels, for example, by means of molecular dynamics methods. The most interesting are problems related with the study of complex processes under real physical conditions. Solving such problems requires the use of high performance computing systems of various types, for example, GRID systems and HPC clusters. Considering the time consuming computational tasks, the need arises of software for automatic and unified monitoring of such computations. A complex computational task can be performed over different HPC systems. It requires output data synchronization between the storage chosen by a scientist and the HPC system used for computations. The design of the computational domain is also quite a problem. It requires complex software tools and algorithms for proper atomistic data generation on HPC systems. The paper describes the prototype of a cloud service, intended for design of atomistic systems of large volume for further detailed molecular dynamic calculations and computational management for this calculations, and presents the part of its concept aimed at initial data generation on the HPC systems.
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Irphan K, Ashiq, et Srisusindhran K. Srisusindhran K. « Reputation based Route Computation for Wireless Ad-Hoc Network Using AODV ». International Journal of Scientific Research 3, no 4 (1 juin 2012) : 200–202. http://dx.doi.org/10.15373/22778179/apr2014/68.
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Sun, Xiaoqiang, F. Richard Yu, Peng Zhang, Weixin Xie et Xiang Peng. « A Survey on Secure Computation Based on Homomorphic Encryption in Vehicular Ad Hoc Networks ». Sensors 20, no 15 (30 juillet 2020) : 4253. http://dx.doi.org/10.3390/s20154253.
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In vehicular ad hoc networks (VANETs), the security and privacy of vehicle data are core issues. In order to analyze vehicle data, they need to be computed. Encryption is a common method to guarantee the security of vehicle data in the process of data dissemination and computation. However, encrypted vehicle data cannot be analyzed easily and flexibly. Because homomorphic encryption supports computations of the ciphertext, it can completely solve this problem. In this paper, we provide a comprehensive survey of secure computation based on homomorphic encryption in VANETs. We first describe the related definitions and the current state of homomorphic encryption. Next, we present the framework, communication domains, wireless access technologies and cyber-security issues of VANETs. Then, we describe the state of the art of secure basic operations, data aggregation, data query and other data computation in VANETs. Finally, several challenges and open issues are discussed for future research.
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Rubio-Montero, Antonio Juan, Angelines Alberto-Morillas, Rosa De Lima Rosa De Lima, Pablo Colino-Sanguino, Jorge Blanco-Yagüe, Manuel Giménez, Fernando Blanco-Marcilla, Esther Montes-Prado, Alicia Acero et Rafael Mayo-García. « Evolution of the maintainability of HPC facilities at CIEMAT headquarters ». Revista UIS Ingenierías 19, no 2 (3 mai 2020) : 85–88. http://dx.doi.org/10.18273/revuin.v19n2-2020009.
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Since its establishment in 1951, CIEMAT has been continuously boosting the use of computation as a research method, deploying innovative computing facilities. Hence, Vectorial, MPP, NUMA, and distributed architectures have been managed at CIEMAT, resultingin an extensive expertise on HPC maintainability as well as on the computational needs of the community related to international projects. Nowadays, the evolution of HPC hardware and software is progressively faster and implies a continuous challenge to increase their availability for the greater number of different initiatives supported. To address this task, the ICT team has been changing towards a flexible management model, with a look toward future acquisitions
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Ubene, Mitchell, Mohammad Heidari et Animesh Dutta. « Computational Modeling Approaches of Hydrothermal Carbonization : A Critical Review ». Energies 15, no 6 (17 mars 2022) : 2209. http://dx.doi.org/10.3390/en15062209.
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Hydrothermal carbonization (HTC) continues to gain recognition over other valorization techniques for organic and biomass residue in recent research. The hydrochar product of HTC can be effectively produced from various sustainable resources and has been shown to have impressive potential for a wide range of applications. As industries work to adapt the implementation of HTC over large processes, the need for reliable models that can be referred to for predictions and optimization studies are becoming imperative. Although much of the available research relating to HTC has worked on the modeling area, a large gap remains in developing advanced computational models that can better describe the complex mechanisms, heat transfer, and fluid dynamics that take place in the reactor of the process. This review aims to highlight the importance of expanding the research relating to computational modeling for HTC conversion of biomass. It identifies six research areas that are recommended to be further examined for contributing to necessary advancements that need to be made for large-scale and continuous HTC operations. The six areas that are identified for further investigation are variable feedstock compositions, heat of exothermic reactions, type of reactor and scale-up, consideration of pre-pressurization, consideration of the heat-up period, and porosity of feedstock. Addressing these areas in future HTC modeling efforts will greatly help with commercialization of this promising technology.
Thèses sur le sujet "HTC computation"
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Farhat, Ahmad. « Trust computation in ad-hoc networks ». FIU Digital Commons, 2005. http://digitalcommons.fiu.edu/etd/3251.
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With the present need for on the move networking, innovative technologies strive to establish a technological basis for managing secure and reliable systems in a highly interconnected information enabled world, and prevent reliance on a fixed networking infrastructure, hence the implementation of ad-hoc networks. There are numerous applications where ad-hoc networks are deployed including military, tele-health and mobile education. As such the need for security is imperative. Not much research work has been invested in the area of trust in ad hoc networks which proves to be a challenging subject relative to the characteristics of these types of networks.
The objective of this thesis was to develop a model for trust computation between the nodes of the network. Eventually, the confidence level for each node was quantified, which lead to a better constancy among the nodes. Therefore, communication was trust worthy, and malicious nodes were punished and secluded from the network.
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McKenzie, Simon Clayton. « Efficient computation of integrals in modern correlated methods ». Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/23993.
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This thesis improves computational efficiency in two domains of quantum chemistry. Firstly, we improve the efficiency of computing atomic orbital (AO) integrals. We efficiently compute effective core potential integrals, relying on novel recursion relations and rigorous screening strategies. Inspired by PRISM, we create an adaptive algorithm to compute two-electron Gaussian geminal integrals, efficiently handling the contracted nature of both the contracted Gaussian-type orbital and geminal. We implement an efficient non-robust density fitting (DF) algorithm for computing the three-electron energy term in the Unsöld-W12 functional using new integral and screening routines. Secondly, we develop low computational scaling and highly parallel algorithms for MP2 energies. These algorithms rely on spatial quadratures of the electronic co-ordinates. We begin with a Localised Molecular Orbital formalism. This algorithm computes the opposite-spin (OS) MP2 energy and scales formally O(N^6) but, with screening strategies, scales asymptotically O(N^2). Unfortunately, the screened quantities reach their asymptotic scaling too slowly. Instead, we adopt a more local AO formalism. This algorithm demonstrates an almost ideal parallel speedup with more than 800 cores and competitive timings against DF-MP2-OS. In our improved AO algorithm, we develop rigorous screening strategies for eliminating insignificant AOs, extend the method to computing the same-spin MP2 energy, remove the prior sparse memory access bottleneck and implement a hybrid parallelisation strategy. We demonstrate a 51% parallel efficiency on 4644 cores, competitive timings and accuracy compared to DF-MP2. Finally, we extend this methodology to compute the MP2-F12(3*A) correction. We present a novel scaled Coulomb-like term approximation and develop efficient quadrature methods and screening strategies. Our scaled approximation and algorithm achieves chemical accuracy across a range of test sets.
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Sen, Sevil. « Evolutionary computation techniques for intrusion detection in mobile ad hoc networks ». Thesis, University of York, 2010. http://etheses.whiterose.ac.uk/998/.
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Mobile ad hoc networks (MANETs) are one of the fastest growing areas of research. By providing communications in the absence of a fixed infrastructure MANETs are an attractive technology for many applications. However, this flexibility introduces new security threats. Furthermore the traditional way of protecting networks is not directy applicable to MANETs. Many conventional security solutions are ineffective and inefficient for the highly dynamic and resource-constrained environments where MANET use might be expected. Since prevention techniques are never enough, intrusion detection systems (IDSs), which monitor system activities and detect intrusions, are generally used to complement other security mechanisms. %due to the dynamic nature %of MANETs, the lack of central points, and their highly constrained nodes. How to detect intrusions effectively and efficiently on this highly dynamic, distributed and resource-constrained environment is a challenging research problem. In the presence of these complicating factors humans are not particularly adept at making good design choices. That is the reason we propose to use techniques from artificial intelligence to help with this task. We investigate the use of evolutionary computation techniques for synthesising intrusion detection programs on MANETs. We evolve programs to detect the following attacks against MANETs: ad hoc flooding, route disruption, and dropping attacks. The performance of evolved programs is evaluated on simulated networks. The results are also compared with hand-coded programs. A good IDS on MANETs should also consider the resource constraints of the MANET environments. Power is one of the critical resources. Therefore we apply multi-objective optimization techniques (MOO) to discover trade-offs between intrusion detection ability and energy consumption of programs, and optimise these objectives simultaneously. We also investigate a suitable IDS architecture for MANETs in this thesis. Different programs are evolved for two architectures: local and cooperative detection in neighbourhood. Optimal trade-offs between intrusion detection ability and resource usage (energy, bandwidth) of evolved programs are also discovered using MOO techniques.
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Natale, Irene. « A study on Friction Boundary Conditions with Unicorn/FEniCS-HPC ». Thesis, KTH, Numerisk analys, NA, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-241920.
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The aim of this thesis is to present and validate a boundary condition formulation for CFD problems that includes a friction parameter. In the first part of the thesis the incompressible Navier-Stokes system of equations and the friction boundary conditions are presented. Then the Finite Element methodology that is used to discretize the problem is given, with particular emphasis to the a-posteriori error estimate, the adaptive algorithm and the numerical tripping included in the flow. Moreover, since FEniCS-HPC is the software on which this thesis leans on, its framework is explained, together with its powerful parallelization strategy. Then the weak formulation of the Navier Stokes system of equation coupled with friction boundary conditions is presented, together with an initial theoretical derivation of the friction coefficient optimal values. Furthermore, in the last chapter, the preliminary results of a validation study for the lift coefficient of the NACA0012 airfoil benchmark model are included and commented in detail. Even if there still are some aspects to be elucidated, we believe that our preliminary results are very promising and that they open a new pathway for simulation development in aerodynamics-related models.Målet med denna avhandling är att presentera och validera ett rand-villkor för CFD problem som inkluderar en friktionsparameter. I den första delen av avhandlingen presenterar vi det inkompressibla Navier-Stokes system av ekvationer och dess randvillkor för friktion. Sedan använder vi oss av Finita Elementmetoden som används för att diskretisera problemet som är presenterat, med en särskild betoning på a posteriori feluppskattningen, den adaptiva algoritmen och den numeriska trippingen som fanns med i flödet. Eftersom denna avhandling helt lutar sig mot FEniCS-HPC mjukvara, förklaras dess ramverk, tillsammans med dess kraftfulla parallelliseringsstrategi. Därefter pre-senterar vi den svaga formuleringen av Navier-Stokes system av ekvationer kopplad till friktionsgränserna, tillsammans med en initiell teoretisk härledning av friktionskoefficientens optimala värden. Vidare, i det sista kapitlet, presenteras de preliminära resultaten av en valide-ringsstudie av lyftkoefficienten för modellen som använts vid benchmarking av NACA0012:s bärytan, som är kommenterad i detalj. Även om det fortfarande finns aspekter som bör belysas tror vi att vårt preliminära resultat är väldigt lovande och att det öppnar en ny väg för simuleringsutveckling i aerodynamikrelaterade modeller.
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Krishnamurthy, Siddhartha. « Peak Sidelobe Level Distribution Computation for Ad Hoc Arrays using Extreme Value Theory ». Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11300.
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Extreme Value Theory (EVT) is used to analyze the peak sidelobe level distribution for array element positions with arbitrary probability distributions. Computations are discussed in the context of linear antenna arrays using electromagnetic energy. The results also apply to planar arrays of random elements that can be transformed into linear arrays.Engineering and Applied Sciences
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Lehmann, Rüdiger. « A universal and robust computation procedure for geometric observations ». Hochschule für Technik und Wirtschaft, 2017. https://htw-dresden.qucosa.de/id/qucosa%3A31843.
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This contribution describes an automatic and robust method, which can be applied to all classical geodetic computation problems. Starting from given input quantities (e.g. coordinates of known points, observations) computation opportunities for all other relevant quantities are found. For redundant input quantities there exists a multitude of different computation opportunities from different minimal subsets of input quantities, which are all found automatically, and their results are computed and compared. If the computation is non-unique, but only a finite number of solutions exist, then all solutions are found and computed. By comparison of the different computation results we may detect outliers in the input quantities and produce a robust final result. The method does not work stochastically, such that no stochastic model of the observations is required. The description of the algorithm is illustrated for a practical case. It is implemented on a webserver and is available for free via internet.Der Beitrag beschreibt ein automatisches und robustes Verfahren, welches auf alle klassischen geodätischen Berechnungsprobleme angewendet werden kann. Ausgehend von vorgelegten Eingabegrößen (z.B. Koordinaten bekannter Punkte, Beobachtungen) werden Berechnungsmöglichkeiten für alle anderen relevanten Größen gefunden. Bei redundanten Eingabegrößen existiert eine Vielzahl von verschiedenen Berechnungsmöglichkeiten aus verschiedenen minimalen Untermengen von Eingabegrößen, die alle automatisch gefunden und deren Ergebnisse berechnet und verglichen werden. Wenn die Berechnung nicht eindeutig ist, aber nur eine endliche Anzahl von Lösungen existiert, dann werden alle Lösungen gefunden und berechnet. Durch den Vergleich verschiedener Berechnungsergebnisse können Ausreißer in den Eingabegrößen aufgedeckt werden und ein robustes Endergebnis wird erhalten. Das Verfahren arbeitet nicht stochastisch, so dass kein stochastisches Modell der Beobachtungen erforderlich ist. Die Beschreibung des Algorithmus wird an einem praktischen Fall illustriert. Er ist auf einem Webserver installiert und über das Internet frei verfügbar.
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Soundarapandian, Manikandan. « Relational Computing Using HPC Resources : Services and Optimizations ». Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/56586.
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Computational epidemiology involves processing, analysing and managing large volumes of data. Such massive datasets cannot be handled efficiently by using traditional standalone database management systems, owing to their limitation in the degree of computational efficiency and bandwidth to scale to large volumes of data. In this thesis, we address management and processing of large volumes of data for modeling, simulation and analysis in epidemiological studies. Traditionally, compute intensive tasks are processed using high performance computing resources and supercomputers whereas data intensive tasks are delegated to standalone databases and some custom programs. DiceX framework is a one-stop solution for distributed database management and processing and its main mission is to leverage and utilize supercomputing resources for data intensive computing, in particular relational data processing.
While standalone databases are always on and a user can submit queries at any time for required results, supercomputing resources must be acquired and are available for a limited time period. These resources are relinquished either upon completion of execution or at the expiration of the allocated time period. This kind of reservation based usage style poses critical challenges, including building and launching a distributed data engine onto the supercomputer, saving the engine and resuming from the saved image, devising efficient optimization upgrades to the data engine and enabling other applications to seamlessly access the engine . These challenges and requirements cause us to align our approach more closely with cloud computing paradigms of Infrastructure as a Service(IaaS) and Platform as a Service(PaaS). In this thesis, we propose cloud computing like workflows, but using supercomputing resources to manage and process relational data intensive tasks. We propose and implement several services including database freeze and migrate and resume, ad-hoc resource addition and table redistribution. These services assist in carrying out the workflows defined.
We also propose an optimization upgrade to the query planning module of postgres-XC, the core relational data processing engine of the DiceX framework. With a knowledge of domain semantics, we have devised a more robust data distribution strategy that would enable to push down most time consuming sql operations forcefully to the postgres-XC data nodes, bypassing its query planner's default shippability criteria without compromising correctness. Forcing query push down reduces the query processing time by a factor of almost 40%-60% for certain complex spatio-temporal queries on our epidemiology datasets.
As part of this work, a generic broker service has also been implemented, which acts as an interface to the DiceX framework by exposing restful apis, which applications can make use of to query and retrieve results irrespective of the programming language or environment.Master of Science
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Bramsäter, Jenny, et Kajsa Lundgren. « Study on the Dynamic Control of Dam Operating Water Levels of Yayangshan Dam in Flood Season ». Thesis, KTH, Industriell ekologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174877.
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Water levels up- and downstream of dams are strongly affected by water levels in the reservoir as well as the discharge of the dam. To ensure that no harm comes to buildings, bridges or agricultural land it is important to ensure that the water level in the reservoir is adjusted to handle large floods. This report studies within what range the water level in the reservoir of the Yayangshan dam, located in Lixian River, can vary without causing any flooding downstream the dam or at the Old and New Babian Bridge located upstream the dam. By calculation of the designed flood, flood routing- and backwater computation, initial water level ranges in the reservoir have been set for the pre-flood, main flood and latter flood season for damages to be avoided. Due to the far distance between the dam site and the bridges, backwater effects had no influence on the limitations of the initial water level in the reservoir.
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Jamasebi, Reza. « COMPUTATIONAL PHENOTYPE DERIVED FROM PHYSIOLOGICAL TIME SERIES : APPLICATION TO SLEEP DATA ANALYSIS ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1220467153.
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San, Juan Sebastián Pablo. « HPC algorithms for nonnegative decompositions ». Doctoral thesis, Universitat Politècnica de València, 2018. http://hdl.handle.net/10251/113069.
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Muchos problemas procedentes de aplicaciones del mundo real pueden ser modelados como problemas matemáticos con magnitudes no negativas, y por tanto, las soluciones de estos problemas matemáticos solo tienen sentido si son no negativas. Estas magnitudes no negativas pueden ser, por ejemplo, las frecuencias en una señal sonora, las intensidades de los pixeles de una imagen, etc.
Algunos de estos problemas pueden ser modelados utilizando un sistema de ecuaciones lineales sobredeterminado. Cuando la solución de dicho problema debe ser restringida a valores no negativos, aparece un problema llamado problema de mínimos cuadrados no negativos (NNLS por sus siglas en inglés). La solución de dicho problema tiene múltiples aplicaciones en ciencia e ingeniería.
Otra descomposición no negativa importante es la Factorización de Matrices No negativas (NMF por sus siglas en inglés). La NMF es una herramienta muy popular utilizada en varios campos, como por ejemplo: clasificación de documentos, aprendizaje automático, análisis de imagen o separación de señales sonoras. Esta factorización intenta aproximar una matriz no negativa con el producto de dos matrices no negativas de menor tamaño, creando habitualmente representaciones por partes de los datos originales.
Los algoritmos diseñados para calcular la solución de estos dos problemas no negativos tienen un elevado coste computacional, y debido a ese elevado coste, estas descomposiciones pueden beneficiarse mucho del uso de técnicas de Computación de Altas Prestaciones (HPC por sus siglas en inglés). Estos sistemas computacionales de altas prestaciones incluyen desde los modernos computadores multinucleo a lo último en aceleradores de calculo (Unidades de Procesamiento Gráfico (GPU), Intel Many Integrated Core (MIC), etc.). Para obtener el máximo rendimiento de estos sistemas, los desarrolladores deben utilizar tecnologías software tales como la programación paralela, la vectoración o el uso de librerías de computación altas prestaciones.
A pesar de que existen diversos algoritmos para calcular la NMF y resolver el problema NNLS, no todos ellos disponen de una implementación paralela y eficiente. Además, es muy interesante reunir diversos algoritmos con propiedades diferentes en una sola librería computacional. Esta tesis presenta una librería computacional de altas prestaciones que contiene implementaciones paralelas y eficientes de los mejores algoritmos existentes actualmente para calcular la NMF. Además la tesis también incluye una comparación experimental entre las diferentes implementaciones presentadas. Esta librería centrada en el cálculo de la NMF soporta múltiples arquitecturas tales como CPUs multinucleo, GPUs e Intel MIC. El objetivo de esta librería es ofrecer un abanico de algoritmos eficientes para ayudar a científicos, ingenieros o cualquier tipo de profesionales que necesitan hacer uso de la NMF.
Otro problema abordado en esta tesis es la actualización de las factorizaciones no negativas. El problema de la actualización se ha estudiado tanto para la solución del problema NNLS como para el calculo de la NMF. Existen problemas no negativos cuya solución es próxima a otros problemas que ya han sido resueltos, el problema de la actualización consiste en aprovechar la solución de un problema A que ya ha sido resuelto, para obtener la solución de un problema B cercano al problema A. Utilizando esta aproximación, el problema B puede ser resuelto más rápido que si se tuviera que resolver sin aprovechar la solución conocida del problema A. En esta tesis se presenta una metodología algorítmica para resolver ambos problemas de actualización: la actualización de la solución del problema NNLS y la actualización de la NMF. Además se presentan evaluaciones empíricas de las soluciones presentadas para ambos problemas. Los resultados de estas evaluaciones muestran que los algoritmos propuestos son más rápidos que resoMolts problemes procedents de aplicacions del mon real poden ser modelats com problemes matemàtics en magnituts no negatives, i per tant, les solucions de estos problemes matemàtics només tenen sentit si son no negatives. Estes magnituts no negatives poden ser, per eixemple, la concentració dels elements en un compost químic, les freqüències en una senyal sonora, les intensitats dels pixels de una image, etc. Alguns d'estos problemes poden ser modelats utilisant un sistema d'equacions llineals sobredeterminat. Quant la solució de este problema deu ser restringida a valors no negatius, apareix un problema nomenat problema de mínims quadrats no negatius (NNLS per les seues sigles en anglés). La solució de este problema te múltiples aplicacions en ciències i ingenieria. Un atra descomposició no negativa important es la Factorisació de Matrius No negatives(NMF per les seues sigles en anglés). La NMF es una ferramenta molt popular utilisada en diversos camps, com per eixemple: classificacio de documents, aprenentage automàtic, anàlisis de image o separació de senyals sonores. Esta factorisació intenta aproximar una matriu no negativa en el producte de dos matrius no negatives de menor tamany, creant habitualment representacions a parts de les dades originals. Els algoritmes dissenyats per a calcular la solució de estos dos problemes no negatius tenen un elevat cost computacional, i degut a este elevat cost, estes descomposicions poden beneficiar-se molt del us de tècniques de Computació de Altes Prestacions (HPC per les seues sigles en anglés). Estos sistemes de computació de altes prestacions inclouen des dels moderns computadors multinucli a lo últim en acceleradors de càlcul (Unitats de Processament Gràfic (GPU), Intel Many Core (MIC), etc.). Per a obtindre el màxim rendiment de estos sistemes, els desenrolladors deuen utilisar tecnologies software tals com la programació paralela, la vectorisació o el us de llibreries de computació de altes prestacions. A pesar de que existixen diversos algoritmes per a calcular la NMF i resoldre el problema NNLS, no tots ells disponen de una implementació paralela i eficient. Ademés, es molt interessant reunir diversos algoritmes en propietats diferents en una sola llibreria computacional. Esta tesis presenta una llibreria computacional de altes prestacions que conté implementacions paraleles i eficients dels millors algoritmes existents per a calcular la NMF. Ademés, la tesis també inclou una comparació experimental entre les diferents implementacions presentades. Esta llibreria centrada en el càlcul de la NMF soporta diverses arquitectures tals com CPUs multinucli, GPUs i Intel MIC. El objectiu de esta llibreria es oferir una varietat de algoritmes eficients per a ajudar a científics, ingeniers o qualsevol tipo de professionals que necessiten utilisar la NMF. Un atre problema abordat en esta tesis es la actualisació de les factorisacions no negatives. El problema de la actualisació se ha estudiat tant per a la solució del problema NNLS com per a el càlcul de la NMF. Existixen problemes no negatius la solució dels quals es pròxima a atres problemes no negatius que ya han sigut resolts, el problema de la actualisació consistix en aprofitar la solució de un problema A que ya ha sigut resolt, per a obtindre la solució de un problema B pròxim al problema A. Utilisant esta aproximació, el problema B pot ser resolt molt mes ràpidament que si tinguera que ser resolt des de 0 sense aprofitar la solució coneguda del problema A. En esta tesis es presenta una metodologia algorítmica per a resoldre els dos problemes de actualisació: la actualisació de la solució del problema NNLS i la actualisació de la NMF. Ademés es presenten evaluacions empíriques de les solucions presentades per als dos problemes. Els resultats de estes evaluacions mostren que els algoritmes proposts son més ràpits que resoldre el problema des de 0 en tots els
Many real world-problems can be modelled as mathematical problems with nonnegative magnitudes, and, therefore, the solutions of these problems are meaningful only if their values are nonnegative. Examples of these nonnegative magnitudes are the concentration of components in a chemical compound, frequencies in an audio signal, pixel intensities on an image, etc. Some of these problems can be modelled to an overdetermined system of linear equations. When the solution of this system of equations should be constrained to nonnegative values, a new problem arises. This problem is called the Nonnegative Least Squares (NNLS) problem, and its solution has multiple applications in science and engineering, especially for solving optimization problems with nonnegative restrictions. Another important nonnegativity constrained decomposition is the Nonnegative Matrix Factorization (NMF). The NMF is a very popular tool in many fields such as document clustering, data mining, machine learning, image analysis, chemical analysis, and audio source separation. This factorization tries to approximate a nonnegative data matrix with the product of two smaller nonnegative matrices, usually creating parts based representations of the original data. The algorithms that are designed to compute the solution of these two nonnegative problems have a high computational cost. Due to this high cost, these decompositions can benefit from the extra performance obtained using High Performance Computing (HPC) techniques. Nowadays, there are very powerful computational systems that offer high performance and can be used to solve extremely complex problems in science and engineering. From modern multicore CPUs to the newest computational accelerators (Graphics Processing Units(GPU), Intel Many Integrated Core(MIC), etc.), the performance of these systems keeps increasing continuously. To make the most of the hardware capabilities of these HPC systems, developers should use software technologies such as parallel programming, vectorization, or high performance computing libraries. While there are several algorithms for computing the NMF and for solving the NNLS problem, not all of them have an efficient parallel implementation available. Furthermore, it is very interesting to group several algorithms with different properties into a single computational library. This thesis presents a high-performance computational library with efficient parallel implementations of the best algorithms to compute the NMF in the current state of the art. In addition, an experimental comparison between the different implementations is presented. This library is focused on the computation of the NMF supporting multiple architectures like multicore CPUs, GPUs and Intel MIC. The goal of the library is to offer a full suit of algorithms to help researchers, engineers or professionals that need to use the NMF. Another problem that is dealt with in this thesis is the updating of nonnegative decompositions. The updating problem has been studied for both the solution of the NNLS problem and the NMF. Sometimes there are nonnegative problems that are close to other nonnegative problems that have already been solved. The updating problem tries to take advantage of the solution of a problem A, that has already been solved in order to obtain a solution of a new problem B, which is closely related to problem A. With this approach, problem B can be solved faster than solving it from scratch and not taking advantage of the already known solution of problem A. In this thesis, an algorithmic scheme is proposed for both the updating of the solution of NNLS problems and the updating of the NMF. Empirical evaluations for both updating problems are also presented. The results show that the proposed algorithms are faster than solving the problems from scratch in all of the tested cases.
San Juan Sebastián, P. (2018). HPC algorithms for nonnegative decompositions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/113069
TESIS
Livres sur le sujet "HTC computation"
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Chuanjiang, Miao, dir. Di 2 jie HNC yu yu yan xue yan tao hui lun wen ji. Beijing : Hai yang chu ban she, 2004.
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Computation, Ad Hoc Committee on Research. Report of the Ad Hoc Committee on Research Computation : A report to the Natural Sciences and Engineering Research Council. Ottawa, Ont : Natural Sciences and Engineering Research Council of Canada, 1990.
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ISPA 2006 (2006 Sorrento, Italy). Frontiers of high performance computing and networking : ISPA 2006 workshops : ISPA 2006 international workshops, FHPCN, XHPC, S-GRACE, GridGIS, HPC-GTP, PDCE, ParDMCom, WOMP, ISDF, and UPWN, Sorrento, Italy, December 4-7, 2006 : proceedings. Berlin : Springer, 2006.
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Sotiris, Nikoletseas, Orponen Pekka et SpringerLink (Online service), dir. Algorithms for Sensor Systems : 7th International Symposium on Algorithms for Sensor Systems, Wireless Ad Hoc Networks and Autonomous Mobile Entities, ALGOSENSORS 2011, Saarbrücken, Germany, September 8-9, 2011, Revised Selected Papers. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012.
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Bar-Noy, Amotz. Algorithms for Sensor Systems : 8th International Symposium on Algorithms for Sensor Systems, Wireless Ad Hoc Networks and Autonomous Mobile Entities, ALGOSENSORS 2012, Ljubljana, Slovenia, September 13-14, 2012. Revised Selected Papers. Berlin, Heidelberg : Springer Berlin Heidelberg, 2013.
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Colloquium on Structural Information and Communication Complexity (17th 2010 İzmir, Turkey). Structural information and communication complexity : 17th international colloquium, SIROCCO 2010, Şirince, Turkey, June 7-11, 2010 : proceedings. Berlin : Springer, 2010.
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Using HPC for Computational Fluid Dynamics. Elsevier, 2015. http://dx.doi.org/10.1016/c2014-0-00508-4.
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Vázquez, Mariano, Peter V. Coveney, Hernan Edgardo Grecco, Alfons Hoekstra et Bastien Chopard, dir. Advanced HPC-based Computational Modeling in Biomechanics and Systems Biology. Frontiers Media SA, 2019. http://dx.doi.org/10.3389/978-2-88945-817-2.
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Evolutionary Algorithms for Mobile Ad Hoc Networks. Wiley, 2014.
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Bouvry, Pascal, Bernabé Dorronsoro, Patricia Ruiz, Grégoire Danoy et Yoann Pigné. Evolutionary Algorithms for Mobile Ad Hoc Networks. Wiley & Sons, Limited, John, 2014.
Trouver le texte intégralChapitres de livres sur le sujet "HTC computation"
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Manuali, Carlo, Alessandro Costantini, Antonio Laganà, Marco Cecchi, Antonia Ghiselli, Michele Carpené et Elda Rossi. « Efficient Workload Distribution Bridging HTC and HPC in Scientific Computing ». Dans Computational Science and Its Applications – ICCSA 2012, 345–57. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31125-3_27.
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Peralta, René. « Dark Encounter Computations ». Dans Secure Mobile Ad-hoc Networks and Sensors, 182–85. Berlin, Heidelberg : Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11801412_17.
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Flocchini, Paola. « Computations by Luminous Robots ». Dans Ad-hoc, Mobile, and Wireless Networks, 238–52. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-19662-6_17.
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Nyhan, Julianne, et Andrew Flinn. « hic Rhodus, hic salta : Tito Orlandi and Julianne Nyhan ». Dans Computation and the Humanities, 75–86. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-20170-2_5.
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Aupy, Guillaume, Anne Benoit, Aurlien Cavelan, Massimiliano Fasi, Yves Robert, Hongyang Sun et Bora Uçar. « Coping with Silent Errors in HPC Applications ». Dans Emergent Computation, 269–92. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-46376-6_11.
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Yao, Frances F. « Algorithmic Problems in Wireless Ad Hoc Networks ». Dans Algorithms and Computation, 1. Berlin, Heidelberg : Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/11602613_1.
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Bari, Ataul, Fangyun Luo, Will Froese et Arunita Jaekel. « Optimal Relay Node Placement and Trajectory Computation in Sensor Networks with Mobile Data Collector ». Dans Ad Hoc Networks, 400–415. Berlin, Heidelberg : Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-17994-5_27.
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Bell, Ron. « The AWE HPC Benchmark ». Dans Computational Science – ICCS 2006, 7. Berlin, Heidelberg : Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11758501_5.
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de la Cruz, Raúl, et Mauricio Araya-Polo. « Modeling Stencil Computations on Modern HPC Architectures ». Dans Lecture Notes in Computer Science, 149–71. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-17248-4_8.
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Bordim, J. L., J. Cui, T. Hayashi, K. Nakano et S. Olariu. « Energy-Efficient Initialization Protocols for Ad-hoc Radio Networks ». Dans Algorithms and Computation, 215–24. Berlin, Heidelberg : Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/3-540-46632-0_23.
Texte intégralActes de conférences sur le sujet "HTC computation"
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Chaquet, Jose M., Carlos Perez et Jaime Quintanal. « Accurate and Efficient Computation of Heat Transfer Coefficient From CFD Simulations ». Dans ASME Turbo Expo 2022 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-81788.
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Abstract Prediction of thermal loads plays an important role in turbomachinery applications. Accurate results require solving multiphysics phenomena using techniques such as conjugate thermal methods. In this context, CFD solvers allow us to obtain heat fluxes at the wall interfaces with solid domains. An important quantity to properly understand the thermal problem is the heat transfer coefficient (HTC, also called film coefficient) which basically is the proportionality constant between the heat flux and the temperature difference between fluid and solid domains. Methods for computing HTCs have been reported in the literature relying on information at the domain interfaces level. In the present paper a new approach taking advantage of the whole fluid domain is described. This proposed method is efficient since only one CFD solution is required for each instant. Several numerical simulations are presented in order to prove that the computed HTC field is able to mimic the CFD solver while maintaining the same operation conditions. Also it is shown how these surrogate models have partial predictive capabilities to perform cheap simulations at different operation conditions. Comparison of experimental data with numerical results confirms the aforementioned performance of the proposed approach, obtaining similar results as methods incorporating only information at boundary walls.
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Al-Zihad, Md, Saad Ahmed Akash, Tamal Adhikary et Md Abdur Razzaque. « Bandwidth allocation and computation offloading for service specific IoT edge devices ». Dans 2017 IEEE Region 10 Humanitarian Technology Conference (R10-HTC). IEEE, 2017. http://dx.doi.org/10.1109/r10-htc.2017.8289012.
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Cotul, Ugur, et Shripad T. Revankar. « Analysis of Passive Tube Condensation With Non-Condensable Gas Using Heat and Mass Analogy Model ». Dans 2021 28th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/icone28-65829.
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Abstract In this study, we used the heat and mass analogy model to be able to predict the heat transfer properties of a condenser tube operating in passive mode. The most important advantage of analogy model comparing boundary layer model is simplicity and fast computation, that’s why it can be applied to various engineering problems for many cases. The heat and mass analogy model is based on the heat transfer balance between liquid film and gas mixture area. The main problem for the liquid film region is the heat transfer coefficient (HTC) which is affected negatively in the presence of non-condensable gas. Therefore, our main goal is to increase the HTC and condensation heat transfer rate by updating the analogy code. In the gas-vapor mixture region, heat transfer mainly occurred as latent condensation and sensible heat transfer. In order to maintain this balance between the mixture and liquid film, the interface temperature is iterated. After defining a specified tolerance value of the heat and mass analogy model codes, this iteration process was started to be used at the entrance of a condenser tube. The gas and vapor mixture is considered to be saturated at the liquid/gas interface in the heat and mass transfer analogy model. Via boundary layer study of species concentration and energy balance, the non-condensable gas effect on condensation is added into the equation. For the condensation heat transfer coefficient of turbulent vapor flow associated with laminar condensate, numerical predictions were made and they were satisfactory. The predictions were compared with the experimental data from the literature to be able to test the model. Non-condensable gas mass fraction and vapor-non-condensable mixture temperature were presented in the form of radial and axial profiles.
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Tallman, James A., et Rahul A. Bidkar. « Heat Transfer Coefficient Characterization for Large Aspect-Ratio Thin Films in Film-Riding Seals ». Dans ASME Turbo Expo 2018 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76168.
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Low-leakage film-riding seals are a key enabling technology for utility-scale supercritical carbon dioxide (sCO2) power cycles. Fluid film-riding rotor-stator seals (operating with sCO2 as the working fluid) are designed to track rotor movements and provide effective sealing by maintaining a tight operating clearance (of the order of several microns) from the spinning rotor. Thin film-riding seals generate viscous shear heat during high-speed operation, and the reliable operation of such thin-film seals depends critically on the designer’s ability to control the thermal deformations of the seal/rotor bearing face, which in turn are tied to the designer’s ability to understand and predict the heat transfer across the seal bearing face. In this paper, we develop a simple axisymmetric thermal-mechanical model of a typical face seal to highlight how the uncertainty in heat transfer coefficient (HTC) on the seal bearing face drives uncertainty in seal deformation predictions, especially when the HTCs are an order of magnitude lower than those predicted with duct-based Dittus-Boelter correlations. This uncertainty in seal bearing face HTCs drives the need for an experimental quantification of HTCs in high-aspect ratio thin films associated with low-leakage film-riding seals. In this paper, we describe a non-rotating experimental test rig designed for estimating the HTCs on the seal bearing face using a shim-heater technique along with IR-camera-based temperature measurements. The experimental set-up consists of a thin metal shim (representing the seal bearing face) forming one wall of a pressurized duct with geometric similarity to a typical thin film of a face seal. Pressurized airflow past the shim is used to simulate the flow field expected in a non-rotating seal. The HTC test data for a non-rotating film (as against the actual seal film with rotating fluid) are lower than the actual seal, and establish a lower bound on the HTCs. This is especially useful for bounding the seal deformation uncertainty, which is vulnerable to the HTCs in the low-HTC regime. We present representative test data that is non-dimensionalized using radial-flow-based Reynolds number and compare these HTC estimates both with the predictions of Dittus-Boelter type correlations, and with the predictions of a 3D computational fluid dynamics (CFD) model. The purpose of the CFD model is to develop a HTC prediction tool for such thin-film surfaces, and the test data are used for validating this predictive model.
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Jafarabadi, Mazdak, Hamidreza Chamani, Amir Malakizadi et Seyed Ali Jazayeri. « A Fast Coupled CFD-Thermal Analysis of a Heavy Duty Diesel Engine Water Cooling System ». Dans ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68163.
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In recent years, the design of an efficient cooling system together with good thermal efficiency for a new engine is becoming a critical task and therefore the need for an accurate and fast thermo-fluid simulation of engine cooling system is of vital importance. In this study, a detailed CFD and thermal FE simulation of a 12 cylinders V-type medium speed heavy duty diesel engine cooling system has been carried out using ANSYS-CFX commercial code. At first, a global model, for one bank with six cylinders, has been simulated using appropriate mesh density which ensures the accuracy of the results together with reasonable computational time. At this stage, the worst cylinder has been selected based on the wall temperature and the cooling flow rate. Later, using the inlet and outlet boundary conditions extracted from the global model, a series of detailed thermo-fluid analyses have been conducted for the worst cylinder with a finer mesh. The subcooled nucleate boiling heat transfer computation is carried out using the boiling departure lift-off (BDL) model, in which the total heat flux is assumed to be additively composed of a forced convective and a nucleate boiling component. In order to obtain the temperature field for components under consideration, a comprehensive thermal analysis has been preformed coupling with the detailed CFD analyses to reach an accepted value through transferring data between the CFD and FEA software. This method leads to an accurate prediction of the wall temperature and heat flux. It is observed that at hot spots, nucleate boiling occurs for low coolant flow regions specifically around the cylinder head’s exhaust port and liner coolant side wall. Also a considerable increment in the Heat Transfer Coefficient (HTC) has been observed on the superheated regions where the boiling is initiated.
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Maffulli, Roberto, et Li He. « Wall Temperature Effects on Heat Transfer Coefficient ». Dans ASME Turbo Expo 2013 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94291.
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Developments of High Pressure Turbine (HPT) blades and vanes are particularly affected by the accuracy and consistency in heat transfer prediction techniques. The conventional wisdom in heat transfer analysis considers that aerodynamics fully determines Heat Transfer Coefficient (HTC) distribution along the blade surface, so that wall temperature should have no influence on HTC. The effect of the wall temperature on the heat transfer coefficient has been rarely studied, although there have been some rather scattered correlations regarding the influence of the wall-inflow temperature ratio on HTC, largely based on simple geometry configurations. There seems to be a need to answer two related questions: a) to what extent the conventional wisdom is valid, in particular for a transonic HPT blading? b) what is a consistent way by which the HTC should be worked out in CFD (as well as in experiment)? In this paper, computational analyses are carried out on the effects of wall thermal boundary condition on external HTC for a 2D Nozzle Guide Vane (NGV) profile. The study is performed by using Fluent® commercial Reynolds-Averaged Navier Stokes Equations solver. Further computations are also made using a coupled solid-fluid Conjugate Heat Transfer (CHT) method with an internally cooled blade. The present results show a strong dependence of HTC on wall temperature, far above that predicted by using the existing correlations, highlighting the importance of upstream boundary layer history on the HTC distribution. Influence of the wall temperature on the trailing edge shock position has been also observed. Based on the results found, a new method is proposed, allowing to model the HTC dependence on wall temperature with much improved accuracy as demonstrated.
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Thorbole, Chandrashekhar K., et Hamid M. Lankarani. « Performance Evaluation of HIC Component Testing Device With a Flexible Neck Using Computational Model ». Dans ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68712.
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The Head Injury Criteria (HIC) compliance is an important aircraft interior furnishing certification. This certification confirms the compliance of the HIC requirement as per 14CFR 23.562 [1] and 14 CFR 25.562 [2]. Full scale crash sled tests are widely used destructive test method to show the required compliance of head injury criteria. This method is costly, time consuming and non repeatable. Factors such as sled pulse shape, belt slack, seating posture of the dummy results change in the dynamic conditions which ultimately affect the HIC value. This poses a significant challenge and high costs to the manufactures to show the compliance of aircraft interior furnishings for the certification process. These factors compel the development of alternative method to certify the cabin furnishings for HIC compliance without consuming aircraft seats, which is more repeatable and non time consuming. The laboratory HIC component tester is the device developed to duplicate the full scale crash HIC result. This device is capable to produce similar dynamic conditions upon impact with the test article resulting duplication of the full scale crash test result. The current model is developed with the rigid neck of polycarbonate unlike the flexible neck of Hybrid II part 572 ATD (Anthropomorphic Test Dummy). This study investigates the scope of improvement in dynamic characteristic of the HCTD (HIC Component Testing Device) with flexible neck. Flexible neck performance is evaluated using validated computational model of the HCTD. The computational model is used to simulate the correlation between the HCTD with rigid neck and HCTD with flexible neck with FSST (Full Scale Sled Test). The result demonstrates that HTCD correlates well with the FSST when flexible neck is used and provides conservative results with rigid neck.
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Wang, Zhiduo, Zhaofang Liu et Zhenping Feng. « Influence of Mainstream Turbulence Intensity on Heat Transfer Characteristics of a HP Turbine Stage With Inlet Hot Streak ». Dans ASME Turbo Expo 2015 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42593.
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An unsteady computational study were carried out for the GE-E3 HP turbine at inflow turbulence intensities of 5%, 10% and 20% accompanying with inlet hot streak (HS) at two circumferential positions (impinging and non-impinging relative to vane leading edge) to analyze the interacted turbulence and HS influences. Several validation studies were performed to investigate the heat transfer prediction ability of shear stress transport (SST) turbulence model coupled with γ-θ transition model. Turbulence decay mechanisms in turbine passage were presented, and the airfoil heat transfer behaviors were explored by means of both time-averaged adiabatic wall temperature and heat transfer coefficient (HTC). The results indicate that increase of inflow turbulence leads to favorable turbine temperature distributions in general, and on the blade and tip surface in particular, especially for the non-impinging case and inflow turbulence increasing from 10% to 20%. While the vane and blade surface area-averaged temperatures are hardly changed, a maximum area-averaged temperature drop of 8.9 K is induced at the tip surface. Higher HTC is observed at vane, blade pressure surface, and suction surface mid region at higher turbulence. However, HTCs at endwall regions of blade suction surface and blade tip are insensitive to the turbulence effect, thus the heat load of these regions is not critical when the inflow turbulence intensity is increased. HS position not only affects the airfoil surface temperature variations, but also slightly affects the vane and blade midspan HTC for the variation of fluid driving temperature.
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Luo, Jiang, Eli H. Razinsky et Hee-Koo Moon. « 3D RANS Prediction of Gas-Side Heat Transfer Coefficients on Turbine Blade and Endwall ». Dans ASME 2011 Turbo Expo : Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46723.
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This paper presents a study using 3D computational fluid dynamics (CFD) based on Reynolds-averaged Navier-Stokes (RANS) equations to predict turbine gas-side heat transfer coefficients (HTC) on the entire airfoil and endwall. The CFD results at different spanwise sections and endwall have been compared with the flat-plate turbulent boundary layer correlation and with the data in a NASA turbine rotor passage with strong secondary flows, under three different flow conditions. The enhancement effects of secondary flow vortices on the blade surface and endwall heat transfer rate have been examined in detail. Analyses were conducted for the impact of Reynolds number and exit Mach number on heat transfer. The SST, k-ε, V2F, and realizable k-ε turbulence models have been assessed. The classical log-law wall-functions have been found to be comparable to the wall-integration methods, but with much reduced sensitivity to inlet turbulence conditions. The migration of hot gas was simulated with a radial profile of inlet temperature. CFD results for mid-span HTCs of two other airfoils were also compared with test data. Overall results are encouraging and indicate improved HTC and temperature predictions from 3D CFD could help optimize the design of turbine cooling schemes.
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Pesek, Ludek, Pavel Snabl et Vitezslav Bula. « HPC FEM Calculations for Damping Estimation of Bladed Disk With Dry-Friction Contacts ». Dans ASME 2020 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/detc2020-22070.
Texte intégralRésumé :
Abstract The experimental set-up for studying dynamical behaviour of the bladed wheel with pre-stressed dry-friction contacts in tie-bosses was built. The numerical solution of the turbine bladed wheel with tie-bosses based on 3D finite element method with surface to surface dry friction contact model is proposed. Comparison of experimental and numerical results of dynamical behaviour and damping estimation of our bladed wheel design yielded a reasonable agreement. Due to dry friction contacts and non-linear solution of 3D FE model it, however, leads to HPC computations and long computation times. The contribution deals with description of proposed computational strategy for damping evaluation and achieved results, too.
Rapports d'organisations sur le sujet "HTC computation"
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Peisert, Sean. Fingerprinting Communication and Computation on HPC Machines. Office of Scientific and Technical Information (OSTI), juin 2010. http://dx.doi.org/10.2172/983323.
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Nugent, Peter. HPC-enabled computation of demand models at scale. Office of Scientific and Technical Information (OSTI), mai 2020. http://dx.doi.org/10.2172/1617377.
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Haehnel, Robert, Scott Christensen, J. Whitlow, Andrew Bauer, Ari Meyer, Gautham Rangarajan, Yonghu Wenren et al. A computational prototyping environment interface for DoD CREATE™-AV Helios simulations. Engineer Research and Development Center (U.S.), mai 2021. http://dx.doi.org/10.21079/11681/40582.
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Computational Prototyping Environment (CPE) is a web-based portal designed to simplify running Department of Defense (DoD) modeling and simulation tools on the DoD Supercomputing Resource Center’s (DSRC) High Performance Computing (HPC) systems. The first of these tools to be deployed in the CPE is an application (app) to conduct parametric studies and view results using the CREATE-AV Helios CFD software. Initial capability includes hover (collective sweep) and forward flight (speed sweep) performance calculations. The CPE Helios app allows for job submission to a DSRC’s HPC system and for the viewing of results created by Helios, i.e., time series and volumetric data. Example data input and results viewing are presented. Planned future functionality is also outlined.
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Sookoor, Tamim I., David L. Bruno et Dale R. Shires. Allocating Tactical High-Performance Computer (HPC) Resources to Offloaded Computation in Battlefield Scenarios. Fort Belvoir, VA : Defense Technical Information Center, décembre 2013. http://dx.doi.org/10.21236/ada593253.
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Ruvinsky, Alicia, Timothy Garton, Daniel Chausse, Rajeev Agrawal, Harland Yu et Ernest Miller. Accelerating the tactical decision process with High-Performance Computing (HPC) on the edge : motivation, framework, and use cases. Engineer Research and Development Center (U.S.), septembre 2021. http://dx.doi.org/10.21079/11681/42169.
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Managing the ever-growing volume and velocity of data across the battlefield is a critical problem for warfighters. Solving this problem will require a fundamental change in how battlefield analyses are performed. A new approach to making decisions on the battlefield will eliminate data transport delays by moving the analytical capabilities closer to data sources. Decision cycles depend on the speed at which data can be captured and converted to actionable information for decision making. Real-time situational awareness is achieved by locating computational assets at the tactical edge. Accelerating the tactical decision process leverages capabilities in three technology areas: (1) High-Performance Computing (HPC), (2) Machine Learning (ML), and (3) Internet of Things (IoT). Exploiting these areas can reduce network traffic and shorten the time required to transform data into actionable information. Faster decision cycles may revolutionize battlefield operations. Presented is an overview of an artificial intelligence (AI) system design for near-real-time analytics in a tactical operational environment executing on co-located, mobile HPC hardware. The report contains the following sections, (1) an introduction describing motivation, background, and state of technology, (2) descriptions of tactical decision process leveraging HPC problem definition and use case, and (3) HPC tactical data analytics framework design enabling data to decisions.
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Brust, Frederick W., Edward F. Punch, Elizabeth Kurth Twombly, Suresh Kalyanam, James Kennedy, Garty R. Hattery, Robert H. Dodds et al. Adoption of High Performance Computational (HPC) Modeling Software for Widespread Use in the Manufacture of Welded Structures. Office of Scientific and Technical Information (OSTI), décembre 2016. http://dx.doi.org/10.2172/1349722.
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Fridman, Eyal, Jianming Yu et Rivka Elbaum. Combining diversity within Sorghum bicolor for genomic and fine mapping of intra-allelic interactions underlying heterosis. United States Department of Agriculture, janvier 2012. http://dx.doi.org/10.32747/2012.7597925.bard.
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Heterosis, the enigmatic phenomenon in which whole genome heterozygous hybrids demonstrate superior fitness compared to their homozygous parents, is the main cornerstone of modern crop plant breeding. One explanation for this non-additive inheritance of hybrids is interaction of alleles within the same locus. This proposal aims at screening, identifying and investigating heterosis trait loci (HTL) for different yield traits by implementing a novel integrated mapping approach in Sorghum bicolor as a model for other crop plants. Originally, the general goal of this research was to perform a genetic dissection of heterosis in a diallel built from a set of Sorghum bicolor inbred lines. This was conducted by implementing a novel computational algorithm which aims at associating between specific heterozygosity found among hybrids with heterotic variation for different agronomic traits. The initial goals of the research are: (i) Perform genotype by sequencing (GBS) of the founder lines (ii) To evaluate the heterotic variation found in the diallel by performing field trails and measurements in the field (iii) To perform QTL analysis for identifying heterotic trait loci (HTL) (iv) to validate candidate HTL by testing the quantitative mode of inheritance in F2 populations, and (v) To identify candidate HTL in NAM founder lines and fine map these loci by test-cross selected RIL derived from these founders. The genetic mapping was initially achieved with app. 100 SSR markers, and later the founder lines were genotyped by sequencing. In addition to the original proposed research we have added two additional populations that were utilized to further develop the HTL mapping approach; (1) A diallel of budding yeast (Saccharomyces cerevisiae) that was tested for heterosis of doubling time, and (2) a recombinant inbred line population of Sorghum bicolor that allowed testing in the field and in more depth the contribution of heterosis to plant height, as well as to achieve novel simulation for predicting dominant and additive effects in tightly linked loci on pseudooverdominance. There are several conclusions relevant to crop plants in general and to sorghum breeding and biology in particular: (i) heterosis for reproductive (1), vegetative (2) and metabolic phenotypes is predominantly achieved via dominance complementation. (ii) most loci that seems to be inherited as overdominant are in fact achieving superior phenotype of the heterozygous due to linkage in repulsion, namely by pseudooverdominant mechanism. Our computer simulations show that such repulsion linkage could influence QTL detection and estimation of effect in segregating populations. (iii) A new height QTL (qHT7.1) was identified near the genomic region harboring the known auxin transporter Dw3 in sorghum, and its genetic dissection in RIL population demonstrated that it affects both the upper and lower parts of the plant, whereas Dw3 affects only the part below the flag leaf. (iv) HTL mapping for grain nitrogen content in sorghum grains has identified several candidate genes that regulate this trait, including several putative nitrate transporters and a transcription factor belonging to the no-apical meristem (NAC)-like large gene family. This activity was combined with another BARD-funded project in which several de-novo mutants in this gene were identified for functional analysis.
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Brust, Frederick W., Edward F. Punch, Elizabeth A. Kurth et James C. Kennedy. SBIR PHASE I FINAL REPORT : Adoption of High Performance Computational (HPC) Modeling Software for Widespread Use in the Manufacture of Welded Structures. Office of Scientific and Technical Information (OSTI), décembre 2013. http://dx.doi.org/10.2172/1108435.
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Or, Etti, David Galbraith et Anne Fennell. Exploring mechanisms involved in grape bud dormancy : Large-scale analysis of expression reprogramming following controlled dormancy induction and dormancy release. United States Department of Agriculture, décembre 2002. http://dx.doi.org/10.32747/2002.7587232.bard.
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The timing of dormancy induction and release is very important to the economic production of table grape. Advances in manipulation of dormancy induction and dormancy release are dependent on the establishment of a comprehensive understanding of biological mechanisms involved in bud dormancy. To gain insight into these mechanisms we initiated the research that had two main objectives: A. Analyzing the expression profiles of large subsets of genes, following controlled dormancy induction and dormancy release, and assessing the role of known metabolic pathways, known regulatory genes and novel sequences involved in these processes B. Comparing expression profiles following the perception of various artificial as well as natural signals known to induce dormancy release, and searching for gene showing similar expression patterns, as candidates for further study of pathways having potential to play a central role in dormancy release. We first created targeted EST collections from V. vinifera and V. riparia mature buds. Clones were randomly selected from cDNA libraries prepared following controlled dormancy release and controlled dormancy induction and from respective controls. The entire collection (7920 vinifera and 1194 riparia clones) was sequenced and subjected to bioinformatics analysis, including clustering, annotations and GO classifications. PCR products from the entire collection were used for printing of cDNA microarrays. Bud tissue in general, and the dormant bud in particular, are under-represented within the grape EST database. Accordingly, 59% of the our vinifera EST collection, composed of 5516 unigenes, are not included within the current Vitis TIGR collection and about 22% of these transcripts bear no resemblance to any known plant transcript, corroborating the current need for our targeted EST collection and the bud specific cDNA array. Analysis of the V. riparia sequences yielded 814 unigenes, of which 140 are unique (keilin et al., manuscript, Appendix B). Results from computational expression profiling of the vinifera collection suggest that oxidative stress, calcium signaling, intracellular vesicle trafficking and anaerobic mode of carbohydrate metabolism play a role in the regulation and execution of grape-bud dormancy release. A comprehensive analysis confirmed the induction of transcription from several calcium–signaling related genes following HC treatment, and detected an inhibiting effect of calcium channel blocker and calcium chelator on HC-induced and chilling-induced bud break. It also detected the existence of HC-induced and calcium dependent protein phosphorylation activity. These data suggest, for the first time, that calcium signaling is involved in the mechanism of dormancy release (Pang et al., in preparation). We compared the effects of heat shock (HS) to those detected in buds following HC application and found that HS lead to earlier and higher bud break. We also demonstrated similar temporary reduction in catalase expression and temporary induction of ascorbate peroxidase, glutathione reductase, thioredoxin and glutathione S transferase expression following both treatments. These findings further support the assumption that temporary oxidative stress is part of the mechanism leading to bud break. The temporary induction of sucrose syntase, pyruvate decarboxylase and alcohol dehydrogenase indicate that temporary respiratory stress is developed and suggest that mitochondrial function may be of central importance for that mechanism. These finding, suggesting triggering of identical mechanisms by HS and HC, justified the comparison of expression profiles of HC and HS treated buds, as a tool for the identification of pathways with a central role in dormancy release (Halaly et al., in preparation). RNA samples from buds treated with HS, HC and water were hybridized with the cDNA arrays in an interconnected loop design. Differentially expressed genes from the were selected using R-language package from Bioconductor project called LIMMA and clones showing a significant change following both HS and HC treatments, compared to control, were selected for further analysis. A total of 1541 clones show significant induction, of which 37% have no hit or unknown function and the rest represent 661 genes with identified function. Similarly, out of 1452 clones showing significant reduction, only 53% of the clones have identified function and they represent 573 genes. The 661 induced genes are involved in 445 different molecular functions. About 90% of those functions were classified to 20 categories based on careful survey of the literature. Among other things, it appears that carbohydrate metabolism and mitochondrial function may be of central importance in the mechanism of dormancy release and studies in this direction are ongoing. Analysis of the reduced function is ongoing (Appendix A). A second set of hybridizations was carried out with RNA samples from buds exposed to short photoperiod, leading to induction of bud dormancy, and long photoperiod treatment, as control. Analysis indicated that 42 genes were significant difference between LD and SD and 11 of these were unique.