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4th international symposium on Radiation Safety and Detection Technology

作者： Kim, Yong Nam Choi, Sang Hyun Jeong, Kyoungkeun Kim, Joo Young Lee, Chang Geol Seong, Jinsil Kim, Chan Hyeong Hanyang Univ Seoul 133791 South Korea Yonsei Univ Seoul 120791 South Korea

Medical linear accelerators operating above 10 MV require door shielding for neutrons in addition to photons. A criterion for choice of optimal configuration of lamination of BPE (Borated Polyethylene) and lead is not clear. Moreover, optimal configuration cannot be determined by the conventional method using an analytical formula and simple measurement. this study performs Monte Carlo simulation of radiation field in a commercial LINAC room with 15 MV X-ray sources. Considering two configuration of lamination such as 'lead-BPE' and 'lead-BPE-lead', dose equivalents are calculated by using the MCNPX code and comparative analyses are performed with each other. the obtained results show that there is no significant difference in neuron shielding between both configurations, whereas lead-BPE-lead is more effective for photon shielding. It is also noted that the absolute values of neutron doses are Much greater than that of photon doses outside as well as inside the door, by three orders of magnitude. As a conclusion, the laminating of lead-BPE is suggested as the optimal configuration from the viewpoint of simplicity in fabrication and handling, even though it has no significant difference from lead-BPE-lead in terms of total dose equivalent.

关键词： photoneutron radiation shielding medical linear accelerator Monte Carlo simulation borated polyethylene

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Performance Evaluation of a Beam-shaping Assembly for Accelerated-BNCT Using the Neutron generation Experiment of ⁷Li(p,n)⁷Be Reaction

Performance Evaluation of a Beam-shaping Assembly for Accele...

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4th international symposium on Radiation Safety and Detection Technology

作者： Kim, Kyung-O Jung, Sang Hoon Kim, Soon Young Kim, Gi-Dong Kim, Jong Kyung Hanyang Univ Dept Nucl Engn Seoul 133791 South Korea Hanyang Univ Innovat Technol Ctr Radiat Safety Seoul 133791 South Korea Korea Inst Geosci & Mineral Resource Taejon South Korea

An experiment for performance evaluation of a beam-shaping assembly to generate therapeutic neutrons has been carried out for accelerator-based boron neutron capture therapy (BNCT). Neutron beams are produced by using Li-7(p,n)Be-7 reaction, which has a high neutron yield for low energy neutrons comparing with other reactions. the manufactured assembly is composed of two moderators, AlF3 and Al, and a surrounding graphite reflector in order to focus the generated neutrons from the Li-target on the epithermal energy range with high intensity and quality. the target neutrons from Li-7(p,n)Be-7 reaction and epithermal neutrons generated from the assembly were measured by He-3 detector. It was convinced from the experiment that the beam-shaping assembly, designed in this Study, can shape the source neutron beam into the effective neutron beam for BNCT of which epithermal neutrons occupy the 87.4 %. the experimental result was verified through the use of Monte Carlo simulation using MCNPX code. Appropriate agreement was found between the calculated and measured results in a wide energy range from 0 to 800 keV.

关键词： BNCT neutron source beam-shaping assembly epithermal neutron proton accelerator

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An optimization Model for the Production Planning of Overall Refinery

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Chinese Journal of Chemical Engineering 2008年第1期16卷 67-70页

作者：高振唐立新金辉徐楠楠 The Logistics Institute Northeastern University Shenyang 110004 Liaoning Institute of Technology Jinzhou 121001 China

this article addresses a production planning optimization problem of overall refinery. the authors formulated the optimization problem as mixed integer linear programming. the model considers the main factors for optimizing the production plan of overall refinery related to the use of run-modes of processing units. the aim of this planning is to decide which run-mode to use in each processing unit in each period of a given horizon, to satisfy the demand, such as the total cost of production and inventory is minimized. the resulting model can be regarded as a generalized lot-sizing problem where a run-mode can produce and consume more than one product. the resulting optimization problem is large-sized and NP-hard. the authors have proposed a column generation-based algorithm called branch-and-price （BP） for solving the interested optimization problem. the model and implementation of the algorithm are described in detail in this article. the computational results verify the effectiveness of the proposed model and the solution method.

关键词： refinery planning lot-sizing optimization column generation

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Loop optimization using hierarchical compilation and kernel decomposition 07

Loop optimization using hierarchical compilation and kernel ...

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5th international symposium on code generation and optimization

作者： Barthou, Denis Donadio, Sebastien Carribault, Patrick Duchateau, Alexandre Jalby, William Univ Versailles PRiSM Lab F-78000 Versailles France Bull SA Les Clayes Sous Bois France Univ Versailles LRC ITACA CEA DAM Versailles France

ISBN: (纸本)9780769527642

the increasing complexity of hardware features for recent processors makes high performance code generation very challenging. In particular, several optimization targets have to be pursued simultaneously (minimizing L1/L2/L3/TLB misses and maximizing instruction level parallelism). Very often, these optimization goals impose different and contradictory constraints on the transformations to be applied. We propose a new hierarchical compilation approach for the generation of high performance code relying on the use of state-of-the-art compilers. this approach is not application-dependent and do not require any assembly hand-coding. It relies on the decomposition of the original loop nest into simpler kernels, typically 1D to 2D loops, much simpler to optimize. We successfully applied this approach to optimize dense matrix muliply primitives (not only for the square case but to the more general rectangular cases) and convolution. the performance of the optimized codes on Itanium 2 and Pentium 4 architectures outperforms ATLAS and in most cases, matches hand-tuned vendor libraries (e.g. MKL).

关键词： Kernel Tiles Optimizing compilers Libraries Hardware Costs Phased arrays Laboratories Constraint optimization Assembly

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Proceedings of the 4th international Scientific symposium on Electric Power Engineering, ELEKTROENERGETIKA 2007

Proceedings of the 4th International Scientific Symposium on...

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4th international Scientific symposium on Electric Power Engineering, ELEKTROENERGETIKA 2007

ISBN: (纸本)9788055304007

the proceedings contain 164 papers. the topics discussed include: the optimization of low-speed powerful diesel generator operation in autonomous power supply systems;new issues of the large scale distributed power generation;analysis of modern technologies in power plants in the system;the prospects of development in nuclear power engineering in Poland;mathematical model of generator - excitation - block transformer system and some results of modeling losses in this system;nonlinear time domain transformer model assessment;the mathematical model and selected transient states of polymerization reactor drive supplied with frequency converter;electromagnetic pumping of liquid metals: selected systems and their numerical modeling;and possibilities of numerical modeling of continual induction heating of nonferrous metal bodies.

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Performance portability on EARth: a case study across several parallel architectures

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CLUSTER COMPUTING-thE JOURNAL OF NETWORKS SOFTWARE TOOLS AND APPLICATIONS 2007年第2期10卷 115-126页

作者： Zhu, Weirong Niu, Yanwei Gao, Guang R. Univ Delaware Dept Elect & Comp Engn Newark DE 19716 USA

Due to the increase of the diversity of parallel architectures, and the increasing development time for parallel applications, performance portability has become one of the major considerations when designing the next generation of parallel program execution models, APIs, and runtime system software. this paper analyzes both code portability and performance portability of parallel programs for fine-grained multi-threaded execution and architecture models. We concentrate on one particular event-driven fine-grained multi-threaded execution model-EARth, and discuss several design considerations of the EARth model and runtime system that contribute to the performance portability of parallel applications. We believe that these are important issues for future high end computing system software design. Four representative benchmarks were conducted on several different parallel architectures, including two clusters listed in the 23rd supercomputer TOP500 list. the results demonstrate that EARth based programs can achieve robust performance portability across the selected hardware platforms without any code modification or tuning

关键词： performance portability code portability EARth programming execution model fine-grained multithreading

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Acquisition of an unknown hopping code in an ultra-wideband FH-OFDM system

Acquisition of an unknown hopping code in an ultra-wideband ...

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4th IEEE international symposium on Wireless Communication Systems 2007, ISWCS'07

作者： Hahtola, Paavo Anttonen, Antti Mämmelä, Aarne Research Centre of Finland Kaitoväylä 1 FI-90571 Oulu Finland

ISBN: (纸本)1424409799

In this paper, we study methods for code acquisition in a burst-type ultra-wideband (UWB) frequency-hopped (FH) orthogonal frequency division multiplexing (OFDM) system. In the first scenario, the time-frequency code (TFC) that controls the frequency-hopping is assumed to be completely unknown to the receiver, while in the other scenario we make simplifying assumptions with regard to the TFC. Data-aided (DA) decision variable generation method is used, which aims at keeping the acquisition time and training data overhead to a minimum. Parallel and serial receiver algorithms are proposed for the scenarios, and an iterative serial method for acquiring the TFC is developed. While the parallel receiver enables fast detection, in some cases it is unfeasible due to its complexity. the receiver using the low-complexity serial approach needs more information about the TFC to ensure efficient operation. Simulation results prove that it achieves good performance when such conditions exist. © 2007 IEEE.

关键词： Frequency hopping

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Stochastic methods for dynamic OVSF code assignment in 3G networks

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4th international symposium on Stochastic Algorithms - Foundations and Applications

作者： Karakoc, Mustafa Kavak, Adnan Kocaeli Univ Dept Elect & Comp Edu TR-41380 Kocaeli Turkey Kocaeli Univ Dept Comp Engn TR-41040 Izmir Turkey

ISBN: (纸本)9783540748700

Orthogonal variable spreading factor (OVSF) codes are widely used to provide variable data rates for supporting different bandwidth requirements in wideband code division multiple access (WCDMA) systems. Many works in the literature have intensively investigated to find an optimal dynamic code assignment scheme for OVSF codes. Unlike earlier studies, which assign OVSF codes using conventional (CCA) or dynamic (DCA) code allocation schemes, in this paper, stochastic optimization methods which are genetic algorithm (GA) and simulated annealing (SA) were applied which population is adaptively constructed according to existing traffic density in the OVSF code-tree. Also, the influences of the GA (selection, crossover and mutation techniques) and the SA (cooling schedules, number of inner loop) parameters were examined on the dynamic OVSF code allocation problem. Simulation results show that the GA and SA provide reduced code blocking probability and improved spectral efficiency when compared to the CCA and DCA schemes.

关键词： code division multiple access

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High quality laser-produced proton beam generation by phase rotation

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international JOURNAL OF MODERN PHYSICS B 2007年第3-4期21卷 319-330页

作者： Noda, Akira Nakamura, Shu Iwashita, Yoshihisa Shirai, Toshiyuki Toncu, Hiromu Souda, Hikaru Daido, Hiroyuki Mori, Michiaki Kado, Masataka Sagisaka, Akito Ogura, Koichi Nishiuchi, Mamiko Orimo, Satoshi Hayashi, Yukio Yogo, Akifumi Pirozhkov, Alexander Bulanov, Serget Esirkepov, Timur Nagashima, Akira Kimura, Toyoaki Tajima, Toshiki Takeuchi, Takeshi Fukumi, Atsushi Li, Zhong Kyoto Univ Inst Chem Res Kyoto 6110011 Japan Japan Atom Energy Agcy Kansai Photon Sci Inst Kyoto 6190215 Japan Natl Inst Radiol Sci Chiba 2638555 Japan

Laser ion production has been studied for downsizing of the accelerator dedicated for cancer therapy. For optimization of various parameters such as pre-pulse condition, target position, laser spot size on the target, laser pulse width and so on, time of flight (TOF) measurement utilizing the detected signal by a plastic scintillation counter played an essential role for real time measurement. Protons up to similar to 900 keV and similar to 600 keV are produced from the thin foil targets of Ti 3 mu m and 5 mu m in thickness, respectively. Modification of the energy distribution of the laser-produced ions with Maxwell distribution by utilizing an RF electric field synchronized to the pulse laser, which is the rotation of the ion beam in the longitudinal phase space (Phase Rotation), has been demonstrated for the first time. By using the Ti Sapphire laser of the wave length and pulse duration of 800 nm and a few hundreds fs, respectively, intensity increase of factor 3 in a certain energy bins is attained creating energy peaks with the energy spread about 7%, which is found to be reproduced with good probability.

关键词： laser ion production : TOF measurement mono-energetic peaks phase rotation

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codeS+ISSS 2007: international Conference on Hardware/Software codesign and System Synthesis

CODES+ISSS 2007: International Conference on Hardware/Softwa...

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codeS+ISSS 2007: 5th international Conference on Hardware/Software codesign and System Synthesis

ISBN: (纸本)9781595938244

the proceeding contains 47 papers. the topics discussed include: temperature-aware processor frequency assignment for MPSoCs using convex optimization;three-dimensional multiprocessor system-on-chip thermal optimization;complexity challenges towards 4th generation communication solutions;locality optimization in wireless applications;a code-generator generator for multi-output instructions;influence of procedure cloning on WCET prediction;compile-time decided instruction cache locking using worst-case execution paths;predictable execution adaptivity through embedding dynamic reconfigurability into static MPSoC schedules;incremental run-time application mapping for homogenous NoCs with multiple voltage levels;a data protection unit for NoC-based architectures;improved response time analysis of tasks scheduled under preemptive round-robin;probabilistic performance risk analysis at system-level;and performance modeling for early analysis of multi-core systems.

关键词： codes (symbols)

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