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Artykuły w czasopismach na temat "Parallel split structures"
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Barron, Yonit. "The Delay Time Profile of Multistage Networks with Synchronization". Mathematics 11, nr 14 (23.07.2023): 3232. http://dx.doi.org/10.3390/math11143232.
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The interaction between projects and servers has grown significantly in complexity; thus, applying parallel calculations increases dramatically. However, it should not be ignored that parallel processing gives rise to synchronization constraints and delays, generating penalty costs that may overshadow the savings obtained from parallel processing. Motivated by this trade-off, this study investigates two special and symmetric systems of split–join structures: (i) parallel structure and (ii) serial structure. In a parallel structure, the project arrives, splits into m parallel groups (subprojects), each comprising n subsequent stages, and ends after all groups are completed. In the serial structure, the project requires synchronization after each stage. Employing a numerical study, we investigates the time profile of the project by focusing on two types of delays: delay due to synchronization overhead (occurring due to the parallel structure), and delay due to overloaded servers (occurring due to the serial structure). In particular, the author studies the effect of the number of stages, the number of groups, and the utilization of the servers on the time profile and performance of the system. Further, this study shows the efficiency of lower and upper bounds for the mean sojourn time. The results show that the added time grows logarithmically with m (parallelism) and linearly with n (seriality) in both structures. However, comparing the two types of split–join structures shows that the synchronization overhead grows logarithmically undr both parallelism and seriality; this yields an unexpected duality property of the added time to the serial system.
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Lee, Jung-Han. "A Novel Meander Split Power/Ground Plane Reducing Crosstalk of Traces Crossing Over". Electronics 8, nr 9 (17.09.2019): 1041. http://dx.doi.org/10.3390/electronics8091041.
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In this paper, a novel meander split power/ground plane is proposed for reducing crosstalk between parallel lines crossing over it. The working mechanism of the meander split scheme is investigated by simulations and measurements. The LC equivalent circuit and transmission line model are developed for modeling interactions between the meander split and the signal lines. The proposed meander structure enhances electromagnetic coupling between split planes. The capacitive coupling across the split ensures signal integrity and magnetic coupling between adjacent finger shaped structures suppresses lateral wave propagation along the split gap, which in turn helps suppress the crosstalk. The effectiveness of the meander split remains valid over very wide frequency ranges (up to 9 GHz). Experimental results show that the proposed structure improves the signal quality and reduces the near/far end crosstalk over 30 dB and 50% in the frequency domain and time domain, respectively.
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RAUBER, THOMAS, i GUDULA RÜNGER. "A DATA RE-DISTRIBUTION LIBRARY FOR MULTI-PROCESSOR TASK PROGRAMMING". International Journal of Foundations of Computer Science 17, nr 02 (kwiecień 2006): 251–70. http://dx.doi.org/10.1142/s0129054106003814.
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Multiprocessor task (M-task) programming is a suitable parallel programming model for coding application problems with an inherent modular structure. An M-task can be executed on a group of processors of arbitrary size, concurrently to other M-tasks of the same application program. The data of a multiprocessor task program usually include composed data structures, like vectors or arrays. For distributed memory machines or cluster platforms, those composed data structures are distributed within one or more processor groups. Thus, a concise parallel programming model for M-tasks requires a standardized distributed data format for composed data structures. Additionally, functions for data re-distribution with respect to different data distributions and different processor group layouts are needed to glue program parts together. In this paper, we present a data re-distribution library which extends the M-task programming with Tlib, a library providing operations to split processor groups and to map M-tasks to processor groups.
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Zhu, Hong, Song Zhang i Chul Ahn. "Sample size considerations for split-mouth design". Statistical Methods in Medical Research 26, nr 6 (24.08.2015): 2543–51. http://dx.doi.org/10.1177/0962280215601137.
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Split-mouth designs are frequently used in dental clinical research, where a mouth is divided into two or more experimental segments that are randomly assigned to different treatments. It has the distinct advantage of removing a lot of inter-subject variability from the estimated treatment effect. Methods of statistical analyses for split-mouth design have been well developed. However, little work is available on sample size consideration at the design phase of a split-mouth trial, although many researchers pointed out that the split-mouth design can only be more efficient than a parallel-group design when within-subject correlation coefficient is substantial. In this paper, we propose to use the generalized estimating equation (GEE) approach to assess treatment effect in split-mouth trials, accounting for correlations among observations. Closed-form sample size formulas are introduced for the split-mouth design with continuous and binary outcomes, assuming exchangeable and “nested exchangeable” correlation structures for outcomes from the same subject. The statistical inference is based on the large sample approximation under the GEE approach. Simulation studies are conducted to investigate the finite-sample performance of the GEE sample size formulas. A dental clinical trial example is presented for illustration.
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Khan, Adeena, Waleed M. S. Fawzy, Syed S. Habib i Mamoona Sultan. "Novel and pragmatic exploration of variation in glottic parameters in non-parallel versus parallel vocal cord CT planes with potential reporting pitfalls". PLOS ONE 18, nr 10 (30.10.2023): e0293659. http://dx.doi.org/10.1371/journal.pone.0293659.
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Oblique orientation of vocal cord demands strict compliance, by technicians and clinicians, to the recommended parallel plane CT scan of larynx. Repercussions of non-compliance has never been investigated before. We aimed to observe influence of non-parallel vocal cord plane CT scan on qualitative and quantitative glottic parameters, keeping parallel plane CT as a standard for comparison. Simultaneous identification of potential suboptimal imaging sequelae as a result of unformatted CT plane was also identified. In this study we included 95 normal adult glottides and retrospectively analyzed their anatomy in two axial planes, non-parallel plane ① and parallel to vocal cord plane ②. Qualitative (shape, structures at glottic level) and quantitative (anterior commissure ACom, vocal cord width VCw, anteroposterior AP, transverse Tr, cross-sectional area CSA) glottic variables were recorded. Multivariate statistical analysis was used to predict pattern and their impact on glottic anatomy. Plane ① displayed supraglottic features in glottis; adipose (90.5%) and split thyroid laminae (70.6%). Other categorical variables: atypical shape, submental structures and multilevel vertebral crossing were also in majority. All glottic dimensions varied significantly between two planes with most in ACom (-5.8mm) and CSA (-15.0 mm2). In contrast, plane ② manifested higher VCw (>73%), Tr (66.3%), CSA (64.2%) and AP (44.2%) measurements. On correlation analysis, variation in ACom, CSA, Tr was positively associated with VC or plane obliquity (p<0.05). This variability was more in obese and short necked subjects. Change in one parameter also modified other significantly i.e., ACom versus AP and CSA versus Tr. Results indicated statistically significant change in subjective and objective anatomical parameters of glottis on non-application of appropriate CT larynx protocol for image analysis hence highlighting importance of image reformation.
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Blelloch, Guy, Daniel Ferizovic i Yihan Sun. "Joinable Parallel Balanced Binary Trees". ACM Transactions on Parallel Computing 9, nr 2 (30.06.2022): 1–41. http://dx.doi.org/10.1145/3512769.
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In this article, we show how a single function, join , can be used to implement parallel balanced binary search trees ( BSTs ) simply and efficiently. Based on join , our approach applies to multiple balanced tree data structures, and a variety of functions for ordered sets and maps. We describe our technique as an algorithmic framework called join-based algorithms . We show that the join function fully captures what is needed for rebalancing trees for a variety of tree algorithms, as long as the balancing scheme satisfies certain properties, which we refer to as joinable trees. We discuss four balancing schemes that are joinable: AVL trees, red-black trees, weight-balanced trees, and treaps. We present a variety of tree algorithms that apply to joinable trees, including insert , delete , union , intersection , difference , split , range , filter , and so on, most of them also parallel. These algorithms are generic across balancing schemes. Many algorithms are optimal in the comparison model, and we provide a general proof to show the efficiency in work for joinable trees. The algorithms are highly parallel, all with polylogarithmic span (parallel dependence). Specifically, the set-set operations union , intersection , and difference have work \( O(m\log (\frac{n}{m}+1)) \) and polylogarithmic span for input set sizes \( n \) and \( m\le n \) . We implemented and tested our algorithms on the four balancing schemes. In general, all four schemes have quite similar performance, but the weight-balanced tree slightly outperforms the others. They have the same speedup characteristics, getting around 73 \( \times \) speedup on 72 cores (144 hyperthreads). Experimental results also show that our implementation outperforms existing parallel implementations, and our sequential version achieves close or much better performance than the sequential merging algorithm in C++ Standard Template Library (STL) on various input sizes.
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Chen, Shuang, Zongqian Shi, Jiajia Sun, Shenli Jia, Mingjie Zhong i Yuxin Ma. "High-throughput particle focusing and separation in split-recombination channel". Journal of Micromechanics and Microengineering 32, nr 2 (14.01.2022): 025007. http://dx.doi.org/10.1088/1361-6439/ac4644.
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Abstract Inertial microfluidic has been widely applied to manipulate particles or bio-sample based on the inertial lift force and Dean Vortices. This technology provides significant advantages over conventional technologies, including simple structure, high throughput and freedom from an external field. Among many inertial microfluidic systems, the straight microchannel is commonly used to produce inertial focusing, which is a phenomenon that particles or cells are aligned and separated based on their size under the influence of inertial lift force. Besides the inertial lift force, flow drag forces induced by the geometrical structures of microchannel can also affect particle focusing. Herein, a split-recombination microchannel, consisting of curved and straight channels, is proposed to focus and separate particles at high flow rate. As compared with the straight channel, the particle focusing in the split-recombination channel is greatly improved, which results from the combined effects of the inertial lift force, the curvature-induced Dean drag force and the structure of split and recombination. Moreover, the distribution of different-sized particles in designed microchannel is investigated. The results indicate that the proposed microchannel not only enhances the particle focusing but also enables the separation of different-sized particles with high throughput. Finally, it is discovered that the larger length of straight channel and curvature radius of curved channel can result in a more efficient particle separation. Another important feature of designed split-recombination microchannel is that it can be arranged in parallel to handle large-volume samples, holding great potential in lab-on-a-chip applications.
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Mosbah, Said, Chemseddine Zebiri, Djamel Sayad, Issa Elfergani, Mohamed Lamine Bouknia, Samira Mekki, Rami Zegadi, Merih Palandoken, Jonathan Rodriguez i Raed A. Abd-Alhameed. "Compact and Highly Sensitive Bended Microwave Liquid Sensor Based on a Metamaterial Complementary Split-Ring Resonator". Applied Sciences 12, nr 4 (18.02.2022): 2144. http://dx.doi.org/10.3390/app12042144.
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In this paper, we present the design of a compact and highly sensitive microwave sensor based on a metamaterial complementary split-ring resonator (CSRR), for liquid characterization at microwave frequencies. The design consists of a two-port microstrip-fed rectangular patch resonating structure printed on a 20 × 28 mm2 Roger RO3035 substrate with a thickness of 0.75 mm, a relative permittivity of 3.5, and a loss tangent of 0.0015. A CSRR is etched on the ground plane for the purpose of sensor miniaturization. The investigated liquid sample is put in a capillary glass tube lying parallel to the surface of the sensor. The parallel placement of the liquid test tube makes the design twice as efficient as a normal one in terms of sensitivity and Q factor. By bending the proposed structure, further enhancements of the sensor design can be obtained. These changes result in a shift in the resonant frequency and Q factor of the sensor. Hence, we could improve the sensitivity 10-fold compared to the flat structure. Subsequently, two configurations of sensors were designed and tested using CST simulation software, validated using HFSS simulation software, and compared to structures available in the literature, obtaining good agreement. A prototype of the flat configuration was fabricated and experimentally tested. Simulation results were found to be in good agreement with the experiments. The proposed devices exhibit the advantage of exploring multiple rapid and easy measurements using different test tubes, making the measurement faster, easier, and more cost-effective; therefore, the proposed high-sensitivity sensors are ideal candidates for various sensing applications.
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Rashid, Mahmood A., Swakkhar Shatabda, M. A. Hakim Newton, Md Tamjidul Hoque i Abdul Sattar. "A Parallel Framework for Multipoint Spiral Search in ab Initio Protein Structure Prediction". Advances in Bioinformatics 2014 (16.03.2014): 1–17. http://dx.doi.org/10.1155/2014/985968.
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Protein structure prediction is computationally a very challenging problem. A large number of existing search algorithms attempt to solve the problem by exploring possible structures and finding the one with the minimum free energy. However, these algorithms perform poorly on large sized proteins due to an astronomically wide search space. In this paper, we present a multipoint spiral search framework that uses parallel processing techniques to expedite exploration by starting from different points. In our approach, a set of random initial solutions are generated and distributed to different threads. We allow each thread to run for a predefined period of time. The improved solutions are stored threadwise. When the threads finish, the solutions are merged together and the duplicates are removed. A selected distinct set of solutions are then split to different threads again. In our ab initio protein structure prediction method, we use the three-dimensional face-centred-cubic lattice for structure-backbone mapping. We use both the low resolution hydrophobic-polar energy model and the high-resolution 20×20 energy model for search guiding. The experimental results show that our new parallel framework significantly improves the results obtained by the state-of-the-art single-point search approaches for both energy models on three-dimensional face-centred-cubic lattice. We also experimentally show the effectiveness of mixing energy models within parallel threads.
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Deng, Xida, Ge Dong, Xuan Dai i Jinxiang Deng. "Compact Full Ka-Band Waveguide Directional Coupler Based on Rectangular Aperture Array with Stairs". Micromachines 12, nr 7 (25.06.2021): 745. http://dx.doi.org/10.3390/mi12070745.
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This article presents a compact 3 dB waveguide directional coupler with full waveguide bandwidth. It consists of a pair of rectangular waveguides with stairs structures in the coupling region. The waveguides are placed parallel to each other along their broad wall, which has a rectangular aperture array. The compact size, broad bandwidth, good in-band coupling flatness, and good return loss are achieved by using the proposed structure. For verification purposes, a prototype of the proposed coupler was designed, manufactured, and measured. The experimental results show that over the full waveguide bandwidth a return loss of input port better than 17.46 dB, coupling strength varying between −2.74 dB and −3.80 dB, power-split unbalance within 0.76 dB, and an isolation better than 20.82 dB were obtained. The length of the coupling region was only 15.82 mm.
Rozprawy doktorskie na temat "Parallel split structures"
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Avetisov, Stepan. "Herschel-Quincke filters for passive vibration mitigation". Electronic Thesis or Diss., Le Mans, 2024. https://cyberdoc-int.univ-lemans.fr/Theses/2024/2024LEMA1018.pdf.
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Les vibrations et les bruits de structure sont généralement des phénomènes indésirables pour des raisons de fiabilité et de confort. De nombreuses approches du contrôle des vibrations ont été étudiées au fil des ans, en utilisant diverses conceptions géométriques, des matériaux d'amortissement ou des stratégies de contrôle actif. En outre, l'allègement des structures mécaniques est un défi majeur en termes de consommation d'énergie, en particulier pour les applications de transport.Dans ces contextes combinés, l'objectif de cette thèse est de développer de nouveaux concepts de contrôle des vibrations en adaptant le principe des filtres de Herschel-Quincke (HQ), traditionnellement appliqué aux ondes acoustiques planes dans les tubes, au domaine des ondes élastiques dans les poutres et les plaques. En acoustique, les filtres HQ exploitent le principe de la différence de marche entre deux tubes parallèles de longueurs variables créés à partir d'un tube primaire, ce qui entraîne une interférence destructive et donc une transmission nulle à certaines fréquences.L'attrait des filtres HQ réside dans leur capacité à fournir de multiples pics de perte de transmission, ce qui constitue une alternative viable aux approches traditionnelles basées sur la résonance. Cette étude étend ce principe aux ondes de flexion en divisant une poutre mince en deux segments de longueur égale mais d'épaisseur différente. La différence de rigidité de flexion qui en résulte induit la différence de phase requise, ce qui conduit au filtrage des ondes. Cette approche fait des filtres HQ une solution prometteuse pour les applications de contrôle des vibrations et du bruit sans augmenter la masse de la structure considérée. Premièrement, le principe HQ pour la dynamique structurelle est analysé théoriquement à travers des modèles basés sur les ondes considérant les ondes longitudinales ou torsionnelles non dispersives et les ondes de flexion dans les poutres. Une étude expérimentale démontre également l'intérêt pratique de cette technique de filtrage. Ensuite, le principe est étendu aux structures de plaques, ce qui conduit à des filtres annulaires qui peuvent entourer une source de vibration et ainsi l'isoler du reste de la plaque. Enfin, des conceptions plus sophistiquées basées sur des arrangements sériels, parallèles ou périodiques de dispositifs structurels HQ sont proposées et analysées afin d'évaluer comment elles peuvent optimiser les performances de filtrage des vibrationsVibration and structure borne noise are generally undesirable phenomena for both the reliability and comfort issues. Many approaches to vibration control have been studied over the years, using various geometrical designs, damping materials, or active control strategies. In addition, lightening mechanical structures is a major challenge in terms of energy consumption, particularly for transport applications. In these combined contexts, the aim of this thesis is to develop new vibration control concepts by adapting the principle of Herschel-Quincke (HQ) filters, traditionally applied to plane acoustic waves in tubes, to the realm of elastic waves in beams and plates. In acoustics, HQ filters exploit the principle of a phase shift between two parallel tubes of varying lengths created from a primary tube, resulting in destructive interference and hence zero transmission at certain frequencies. The attractiveness of HQ filters lies in their capacity to provide multiple transmission loss peaks, presenting a viable alternative to traditional resonance-based approaches. This study extends this principle to bending waves by partitioning a thin beam into two segments of equal length but different thicknesses. The resulting disparity in bending stiffness induces the requisite phase difference, leading to wave filtering. This approach positions HQ filters as a promising solution for vibration and noise control applications without increasing the mass of the considered structure. First, the HQ principle for structural dynamics is theoretically analysed through wave based models considering non dispersive longitudinal or torsional waves and bending waves in beams. An experimental study also demonstrates the practical interest of this filtering technique. Then, the principle is extended to plates structures, leading to annular filters that may surround a vibration source and so isolate it from the rest of the plate. Third, some more sophisticated designs based on serial, parallel or periodic arrangements of structural HQ devices are proposed and analyzed to assess how they can optimize vibration filtering performance
Części książek na temat "Parallel split structures"
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Klumpp, Gerson. "Permic". W The Oxford Guide to the Uralic Languages, 471–86. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780198767664.003.0025.
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This chapter provides historical and structural background information on shared innovations of the two Permic sub-branches, Komi and Udmurt. The Permic languages are closely related. According to the evidence of loanwords from Western Turkic, Komi split off from Proto Permic towards the end of the first millenium AD. The languages share the same phoneme inventories, the same case systems, they developed parallel evidential past-tense forms, and, of course have a common lexical stock. However, from a syntactical point of view they show clear differences: while Udmurt is strictly SOV and more often aligns with its Turkic neighbours, Tatar and Chuvash, Komi is less strictly SOV and parallels more often Russian structures. In addition to presenting common Permic traits, this chapter also aims at defining some differences from the other two Uralic branches of the larger Volga-Kama area, Mari and Mordvin.
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Xiao*, Xiao-yi, i K. C. Nicolaouꝉ. "High-throughput combinatorial synthesis of discrete compounds in multimilligram quantities: non-chemical encoding and directed sorting". W Combinatorial Chemistry, 75–94. Oxford University PressOxford, 2000. http://dx.doi.org/10.1093/oso/9780199637546.003.0004.
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Abstract Over the past few years the pharmaceutical community’s need to generate and screen chemical libraries with large diversity has fuelled the rapid development of combinatorial chemistry (1, 2). Research areas such as high-throughput solution (3, 4) and solid phase (5-7) synthesis, the development of novel solid supports and linkers (Chapters 6 and 7) (8, 9), as well as new powerful encoding strategies (10-14) (Chapter 1) have received exceptional attention due to their central role in the development of this field. The chemical encoding strategies (15, 16), coupled with the split and pool technique (17) (Chapters 1-3) greatly increase the efficiency of combinatorial synthesis and screening. However, these strategies produce each member of the library in very small amounts (nanograms to micrograms), making subsequent multiple screenings and characterization procedures quite difficult. Although traditional parallel synthesis (18, 19) in combination with the remarkable recent progress in laboratory automation (19) produces larger quantities of material, it still lacks the efficiency of the split and pool technique particularly for the preparation of very large libraries. We have recently developed two new combinatorial synthesis strategies employing non-chemical encoding and directed sorting in a batch synthesis fashion (10, 11) that combine both the advantages of split and pool and parallel synthesis. These strategies are capable of producing large combinatorial libraries and delivering milligram quantities of each library member. This chapter discusses the development of these two non-chemical encoding techniques: radiofrequency (Rf) tagging (10) and bar coding (11) in combination with a directed sorting strategy, and their application to the synthesis of combinatorial libraries of a variety of chemical structures.
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Li, Yinbao, Songshan Yu, Meng Li, Zengzeng Jia i Yuxuan Song. "QDTree: Quasi-Density-Tree Accelerates Free Space Detection with MMW Radar Point Cloud". W Advances in Transdisciplinary Engineering. IOS Press, 2024. http://dx.doi.org/10.3233/atde240043.
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In autonomous driving, free space detection based on 3+1D radar point cloud severely suffers from the existence of noises. To tackle this problem, we propose the novel non-data-driven Quasi-Density-Tree (QDTree) method, where no distance metrics are employed, and within the QDTree we use voting tool to analyse its nodes in terms of point cloud density or SNR, resulting noise data effectively filtered. We further split left point clouds into static and moving types according to Doppler to detect free space and Gaussian Mixture Method was used to generate safety confidence. The QDTree structure and point cloud dichotomy allow us to apply parallel computation in free space detection. Furthermore, the proposed free space detection method outperforms those state-of-the-art algorithms in terms of computation speed and result accuracy. Specifically, the proposed free space detection method consumes less than 30ms (with parallel computation, it is within 18ms) when processing 5-frame accumulated 4-corner-radar point cloud (∼5000 points) and hence it is adequate to meet real-time requirements.
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Bilbao-Castro, J. R., I. García i J. J. Fernández. "Grid Computing in 3D Electron Microscopy Reconstruction". W Grid and Cloud Computing, 881–98. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-4666-0879-5.ch407.
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Three-dimensional electron microscopy allows scientists to study biological specimens and to understand how they behave and interact with each other depending on their structural conformation. Electron microscopy projections of the specimens are taken from different angles and are processed to obtain a virtual three-dimensional reconstruction for further studies. Nevertheless, the whole reconstruction process, which is composed of many different subtasks from the microscope to the reconstructed volume, is not straightforward nor cheap in terms of computational costs. Different computing paradigms have been applied in order to overcome such high costs. While classic parallel computing using mainframes and clusters of workstations is usually enough for average requirements, there are some tasks which would fit better into a different computing paradigm – such as grid computing. Such tasks can be split up into a myriad of subtasks, which can then be run independently using as many computational resources as are available. This chapter explores two of these tasks present in a typical three-dimensional electron microscopy reconstruction process. In addition, important aspects like fault-tolerance are widely covered; given that the distributed nature of a grid infrastructure makes it inherently unstable and difficult to predict.
Streszczenia konferencji na temat "Parallel split structures"
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Holloway, Mary V., Donald E. Beasley i Michael E. Conner. "Investigation of Swirling Flow in Rod Bundle Subchannels Using Computational Fluid Dynamics". W 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89068.
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The fluid dynamics for turbulent flow through rod bundles representative of those used in pressurized water reactors is examined using computational fluid dynamics (CFD). The rod bundles of the pressurized water reactor examined in this study consist of a square array of parallel rods that are held on a constant pitch by support grids spaced axially along the rod bundle. Split-vane pair support grids are often used to create swirling flow in the rod bundle in an effort to improve the heat transfer characteristics for the rod bundle during both normal operating conditions and in accident condition scenarios. Computational fluid dynamics simulations for a two subchannel portion of the rod bundle were used to model the flow downstream of a split-vane pair support grid. A high quality computational mesh was used to investigate the choice of turbulence model appropriate for the complex swirling flow in the rod bundle subchannels. Results document a central swirling flow structure in each of the subchannels downstream of the split-vane pairs. Strong lateral flows along the surface of the rods, as well as impingement regions of lateral flow on the rods are documented. In addition, regions of lateral flow separation and low axial velocity are documented next to the rods. Results of the CFD are compared to experimental particle image velocimetry (PIV) measurements documenting the lateral flow structures downstream of the split-vane pairs. Good agreement is found between the computational simulation and experimental measurements for locations close to the support grid.
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Andreozzi, Assunta, Bernardo Buonomo, Oronzio Manca i Sergio Nardini. "Experimental Investigation on the Effect of Longitudinal Aspect Ratio on Natural Convection in Inclined Channels Heated Below". W ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95526.
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In this paper an experimental investigation on natural convection in air in inclined channels with rectangular transversal section and lower wall heated at uniform heat flux is carried out. Wall temperature measurements and flow visualization are presented. The results allow investigating on the effect of the distance between the two principal parallel walls and of the inclination angle. The experiments are accomplished for two channel gap values: 20 and 40 mm. The inclination angle is equal to 80° and 88°. The flow development and the shape of flow transitions along the channel are visualized. Flow visualization allows to describe the secondary motion inside an inclined channel. Flow separation region along the lower heated plate begins at lower axial coordinate as the wall heat flux, the inclination angle and the channel gap are greater. The flow separation depends also on transversal coordinate. The detected secondary structures pass from thermals to plumes and vortices. Along the plane parallel to the heated wall, the visualization shows that thermal plumes split in V-shaped structures. For the largest considered channel gap value the instability phenomena in the channel are stronger and chaotic motion in the channel outlet zone is observed. When the channel gap value increases wall temperatures become lower because the higher distance between the walls determines a greater mass flow rate and an increase in the heat transfer.
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Li, Yanjing, Zhaosong Lu i Jeremy J. Michalek. "Diagonal Quadratic Approximation for Parallelization of Analytical Target Cascading". W ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-35566.
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Analytical Target Cascading (ATC) is an effective decomposition approach used for engineering design optimization problems that have hierarchical structures. With ATC, the overall system is split into subsystems, which are solved separately and coordinated via target/response consistency constraints. As parallel computing becomes more common, it is desirable to have separable subproblems in ATC so that each subproblem can be solved concurrently to increase computational throughput. In this paper, we first examine existing ATC methods, providing an alternative to existing nested coordination schemes by using the block coordinate descent method (BCD). Then we apply diagonal quadratic approximation (DQA) by linearizing the cross term of the augmented Lagrangian function to create separable subproblems. Local and global convergence proofs are described for this method. To further reduce overall computational cost, we introduce the truncated DQA (TDQA) method that limits the number of inner loop iterations of DQA. These two new methods are empirically compared to existing methods using test problems from the literature. Results show that computational cost of nested loop methods is reduced by using BCD and generally the computational cost of the truncated methods, TDQA and ALAD, are superior to other nested loop methods with lower overall computational cost than the best previously reported results.
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HAMDI, ISMAIL, SYLVAIN MAGNE, STÉPHANE ROUGEAUTLT, PHILIPPE MONGABURE, SANDRA VASIC, PIERRE-ETIENNE CHARBONNEL, FAN WANG, ESTELLE HERVÉ-SECOURGEON i FRANÇOIS VOLDOIRE. "DAMAGE ASSESSMENT IN A REINFORCED CONCRETE STRUCTURE UNDER QUASI-STATIC SHEAR LOADING USING OFDR-BASED FIBRE-OPTIC DISTRIBUTED STRAIN MONITORING". W Structural Health Monitoring 2023. Destech Publications, Inc., 2023. http://dx.doi.org/10.12783/shm2023/37034.
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EDF and CEA have established an experimental program to improve knowledge of the behavior of wall-slab junctions under both out-of-plane bending and in-plane shear. The program involved reduced-scale mock-ups made of reinforced concrete (RC) that are representative of the structural elements of nuclear plant buildings. In parallel to vast experimental campaigns, numerical models of the junction under study are derived and calibrated in order to improve the computation of building responses under seismic excitations. The analysis of damaging process of these structures is reproduced by nonlinear numerical simulations, realized within the Finite Element framework CAST3M developed at CEA (www-cast3m.cea.fr/) and code Aster (https://code-aster.org), which account for steel plasticity and concrete damage, including crack propagation based on loading conditions and history. Of all the distributed techniques applicable to the Structural Health Monitoring (SHM) of RC structures, Optical Frequency-Domain Reflectometry (OFDR) is well suited because of its high spatial resolution. The OFDR principle relies on swept-wavelength homodyne interferometry. Light from a tunable laser source is split and sent through sensing and reference fibers, both being arms of an interferometer. The backscattered light recombines at an optical detector and an interferogram is recorded as the laser frequency is tuned. The spectral-domain signal is then Fourier-Transformed to yield the backscattering profile along the fiber. Finally, the fiber is segmented into successive centimeter-long gage lengths and a cross-correlation procedure provides the strain profile with respect to a reference state. We implemented the OBR4600 OFDR device from Luna Innovations. The OBR 4600 is a single channel device that provides static distributed strain monitoring over a range of 70 m, with an accuracy in strain of ±5 μm/m, a spatial resolution (gage length) of about 5 mm, and a readout time of typically 10 seconds. On the last mock-up of the experimental program, the jacks applied quasi-static displacements ranging from 0.69 mm to 11.49 mm, yielding progressive structural damage and eventually reaching concrete crack and steel plasticity. Strain profiles and natural frequencies were determined and compared to the modeling. Distributed Fiber Optic Sensing (DFOS) results provide access to continuous strain distributions along the instrumented rebars, localize deficiencies and local deformations around rebar crossings and also the emergence of concrete degradations in the joint. The OFDR technique enables highly reliable in-situ SHM of damage mechanisms within concrete structures, providing effective data for model verification and validation used in safety-related structures assessment.
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Yunfei Mao, Bin Chen, Bihua Zhou, Liwei Cheng i Qun Wu. "Parallel implementation of the split-field FDTD method for the analysis of periodic structure". W 2008 8th International Symposium on Antennas, Propagation and EM Theory. IEEE, 2008. http://dx.doi.org/10.1109/isape.2008.4735357.
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La, Dong-Sheng, i Wei-Hong Han. "Compact wideband band-pass filter using microstrip parallel-coupled line structure with complementary split ring resonator". W 2016 IEEE International Conference on Microwave and Millimeter Wave Technology (ICMMT). IEEE, 2016. http://dx.doi.org/10.1109/icmmt.2016.7761775.
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Salimijazi, H. R., F. Azarmi, T. W. Coyle i J. Mostaghimi. "Relationship between the Elastic Modulus and Microstructure in Vacuum Plasma Sprayed Structures". W ITSC2005, redaktor E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2005. http://dx.doi.org/10.31399/asm.cp.itsc2005p1208.
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Abstract The structure of thermally sprayed deposit consists of individual lamellae formed from melted and re-solidified particles, along with unmelted and partially melted particles, pores, microcracks, and splat boundaries. The elastic modulus of a vacuum plasma sprayed Ti-6Al-4V alloy parallel to the splat plane determined by standard uniaxial tensile testing was found to be approximately 30% lower than that of conventionally processed materials with the same level of porosity. The relationship between the elastic modulus and the microstructure was studied using an in-situ tensile testing stage in an optical microscope combined with analytical and finite element models. An idealized microstructure was used for the analytical model, which yielded an estimate of the modulus higher than that measured. The finite-element program OOF was also used to compute the elastic modulus based on micrographs of polished and etched surfaces and predicted a reduction of about 37% in the modulus.
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Radkowski, Rafael, i James Oliver. "Simulation of Motion Parallax for Monitor-Based Augmented Reality Applications". W ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-13032.
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The paper presents a method for the simulation of motion parallax for monitor-based Augmented Reality (AR) applications. Motion parallax effects the relative movement between far and close objects: near objects appear moving faster than far objects do. This facilitates the perception of depth, distances, and the structure of geometrically complex objects. Today, industrial AR applications are equipped with monitor-based output devices, e.g., for design reviews. Thus this important depth cue is omitted because all objects appear as one even layer on screen. As a result, the assessment of complex structures becomes more difficult. The method presented in this paper utilizes depth images to create layered images: multiple images in which objects in a video image are split up with respect to their distance too a video camera. Using head tracking, the single layers are relatively moved with respect to the user’s head position. This simulates motion parallax. Virtual objects superimpose the final image to complete the AR scene. The method was prototypically realized, the results show its feasibility.
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Pliszka, Pawel, i Partha P. Banerjee. "Propagation of fundamental and second harmonic beams in square law media". W OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.tuff5.
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Using parallel computers, we numerically study the propagation of beams in a quadratically nonlinear medium with a square law transverse distribution of the index of refraction, as in a graded index optical fiber. A symmetrized split-step beam propagation method is used to solve the coupled differential equations in the paraxial approximation. We show that in the range of moderate intensities, a periodic solution for the fundamental beam resulting from the superposition of many linear modes is only weakly perturbed. The second harmonic transverse profile, however, is generally nonperiodic and usually exhibits a ring structure. The single-mode solution becomes generally unstable, and periodic changes of the transverse intensity profile emerge.
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Ogawa, Takanobu. "A Numerical Algorithm Based on a Tree Data for an Anisotropically Adaptive Cartesian Mesh". W ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45532.
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In an adaptive Cartesian mesh approach, a rectangular mesh is recursively and locally refined and mesh can be automatically generated for complex flow geometry. In this study, a numerical algorithm is developed for an adaptive Cartesian mesh. The tree data is employed to organize the adaptively refined meshes. With this data structure, mesh adaptation becomes very flexible and the algorithm developed for a conventional flow solver can be adapted with less modification. The algorithm can be extended for the anisotropic mesh refinement which is efficient for a boundary layer problem. Parallelization of the developed algorithm is also done in the SPMD paradigm. The domain decomposition technique is used and a tree data structure is split so that computational load should be balanced. Parallel efficiency is examined on a PC cluster.