Modeling of Supersonic Combustor Flows using Parallel Computing

Computational Fluid Dynamics (CFD) has matured rapidly in the past 20 years and is now an important tool for analyzing and understanding complex fluid flows. Since 1985, CFD has played a vital role in the study of hypersonic flight. It has provided the capability for scientists and engineers to model both internal and external hypersonic flow-fields. Such flows are often impractical or impossible to analyze in laboratory conditions. In particular, the recent application of CFD to the modeling of internal reacting supersonic combustor flows has significantly advanced the understanding of such flows and has increased confidence in the predictive ability of codes. The purpose of these efforts has been to provide the hypersonic propulsion community with realistic large-scale applications of CFD and to use these solutions in direct support of engineering analysis and design of hypersonic vehicles. Although these applications have been successful to date, expectations and requirements arc increasing dramatically for both faster turn-around of solutions and for more detailed and accurate solutions (hence requiring greater computational mesh refinement, more complete chemistry and turbulence models, etc.). In order to begin to meet these requirements, a ten-fold or greater increase in computational efficiency is required, relative to current supercomputing capabilities. This increase can be achieved easily by suitably programming existing CFD technology on existing distributed memory parallel computing machines or multicomputers. This paper presents and analyzes the results obtained to date in an investigation aimed at the application of parallel computing to the simulation of scramjet combustor flow-fields

The Computation of Supersonic Combustor Flows using Multi-Computers

An explicit computational fluid dynamics (CFD) computer code with parallel processing capability has been developed for the purpose of simulating internal high-speed reacting flows. The code solves the three-dimensional Navier-Stokes equations for compressible flows. The CFD code can be executed on either sequential (single processor) computers or multi-computers (multiple processor machines with distributed memory and message passing between processors). The parallel implementation involves homogeneous domain decomposition between processors with message passing needed only between neighbor processors. The code is validated for a compression ramp, an expansion ramp, a viscous flat plate, and a viscous flat plate with wall injection. These results are presented and discussed. Also, parallel timings, relative speed-ups, and relative efficiencies are presented and discussed. These preliminary results indicate that parallel processing should solve the resource and speed shortages currently encountered with sequential computers for problems of interest

Asynchronous Parallel Schemes: A Survey

It is well known that synchronization and communication delays are the major sources of performance degradation of synchronous parallel algorithms. It has been shown that asynchronous implementations have the potential to reduce the overhead to minimum. This paper surveys the existing asynchronous schemes and the sufficient conditions for the convergence of the surveyed schemes. Some comparisons among these schemes are also presented

應用於適性化數位學習系統之存取控制機制研究

適性化學習(Adaptive Learning)近年來成為一項熱門的研究，許多專家學者針對學習者不同的學習需求，提出多種適性化學習路徑規劃機制，給予學習者個人化的學習路徑與教材導覽，以提升學習者的學習成效與學習效率。而隨著數位學習系統被廣泛的使用於各產官學界，系統的存取控制議題即成為一項重要的研究。過去有許多專家學者為資訊系統中使用者的存取權限管理提出不同的存取控制機制，可惜的是無法完全適用於適性化數位學習系統。因此本研究在綜觀目前數位學習系統的存取控制需求與適性化學習最新研究後，以適性化數位學習系統中學習資源的存取控制問題著手，結合主體角色、教學規則與授體角色的設計方式，改善數位學習系統導入適性化學習路徑導覽後，產生的過度授權及授權規則數量過多的問題，並且針對課程編輯權限委任授權之需求，提出一套適性化數位學習系統所需之存取控制機制，不僅能有效的控管學習資源的存取、降低授權規則數量及增加資源分享性，更提升了課程活動樹設計上的彈性。In recent years, the adaptive learning becomes a hot spot topic, many various planning mechanisms of adaptive learning according to different learning styles, requirements and progress of learners are proposed to promote the learning effectiveness and efficiency of learners. Due to e-learning system is widely used in the manufacturing, official and academia, an access control in e-learning system becomes another important issue. During the past decade, researchers proposed different access control mechanisms for e-learning system to manage the users' authorizations, however, they can not be completely suited for the adaptive e-learning system. As the results, the proposed research focuses on the problems of access control in learning resources and delegations of e-learning system, not only to reduce the costs of system management but also to increase the uses of resource sharing

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

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Search for supersymmetry in events with one lepton and multiple jets in proton-proton collisions at root s=13 TeV

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Search for anomalous couplings in boosted WW/WZ -> l nu q(q)over-bar production in proton-proton collisions at root s=8TeV

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