652 research outputs found
A Weighting Function Model for Unsteady Open Channel Friction: Raw code and output
No full textMatlab source code and Raw Origin Lab file (.opj) for a weighting function model simulating unsteady open channel friction slopes. This material is provided as is. Methods (formulas) and Figures are explained further in the related article "A Weighting Function Model for Unsteady Open Channel Friction" by Junwei Zhou; Weimin Bao; Geoffrey R. Tick; Qing Cao; and Fanghong Ye.</p
Agent-based resource management for grid computing
No full textA computational grid is a hardware and software infrastructure that provides
dependable, consistent, pervasive, and inexpensive access to high-end
computational capability. An ideal grid environment should provide access to the
available resources in a seamless manner. Resource management is an important
infrastructural component of a grid computing environment. The overall aim of
resource management is to efficiently schedule applications that need to utilise the
available resources in the grid environment. Such goals within the high
performance community will rely on accurate performance prediction capabilities.
An existing toolkit, known as PACE (Performance Analysis and Characterisation
Environment), is used to provide quantitative data concerning the performance of
sophisticated applications running on high performance resources. In this thesis an
ASCI (Accelerated Strategic Computing Initiative) kernel application, Sweep3D,
is used to illustrate the PACE performance prediction capabilities. The validation
results show that a reasonable accuracy can be obtained, cross-platform
comparisons can be easily undertaken, and the process benefits from a rapid
evaluation time. While extremely well-suited for managing a locally distributed
multi-computer, the PACE functions do not map well onto a wide-area
environment, where heterogeneity, multiple administrative domains, and communication irregularities dramatically complicate the job of resource
management. Scalability and adaptability are two key challenges that must be
addressed.
In this thesis, an A4 (Agile Architecture and Autonomous Agents) methodology is
introduced for the development of large-scale distributed software systems with
highly dynamic behaviours. An agent is considered to be both a service provider
and a service requestor. Agents are organised into a hierarchy with service
advertisement and discovery capabilities. There are four main performance
metrics for an A4 system: service discovery speed, agent system efficiency,
workload balancing, and discovery success rate.
Coupling the A4 methodology with PACE functions, results in an Agent-based
Resource Management System (ARMS), which is implemented for grid
computing. The PACE functions supply accurate performance information (e. g.
execution time) as input to a local resource scheduler on the fly. At a meta-level,
agents advertise their service information and cooperate with each other to
discover available resources for grid-enabled applications. A Performance
Monitor and Advisor (PMA) is also developed in ARMS to optimise the
performance of the agent behaviours.
The PMA is capable of performance modelling and simulation about the agents in
ARMS and can be used to improve overall system performance. The PMA can
monitor agent behaviours in ARMS and reconfigure them with optimised
strategies, which include the use of ACTs (Agent Capability Tables), limited
service lifetime, limited scope for service advertisement and discovery, agent
mobility and service distribution, etc.
The main contribution of this work is that it provides a methodology and
prototype implementation of a grid Resource Management System (RMS). The
system includes a number of original features that cannot be found in existing
research solutions
Rh/chiral sulfinylphosphine catalyzed asymmetric 1,4-addition of arylboronic acids to chalcones
No full textA general method to obtain enantioenriched 1,3,3-triarylpropan-1-ones bearing a diarylmethine stereocenter was developed using Rh/chiral sulfinylphosphine catalyzed 1,4-addition of arylboronic acids to chalcones. The catalysis progressed smoothly in the presence of 2 mol % catalyst formed in situ from [Rh(C2H4)(2)Cl](2) and chiral tert-butanesulfinylphosphine and gave the adducts with up to 99% yield and 98% ee. (C) 2012 Elsevier Ltd. All rights reserved
The influence of TiO<sub>2</sub> nanoparticle incorporation on surface potential decay of corona-resistant polyimide nanocomposite films
No full textPI nanocomposite films containing surface modified nanoparticles by employing silane coupling agent were prepared using in-situ dispersion polymerization process. The surface potential decay measurements on films were investigated over the different negative corona-charged voltages and times in a controlled environment where temperature and relative humidity were kept at 21 ºC and 45%, respectively. There is a significant change in the surface potential decay characteristics after nano-fillers were introduced into polyimide. The surface potential decay pattern depends also on the amount of nano-fillers. The possible surface potential decay and corona resistance mechanisms responsible for the observed phenomena were discussed
Chiral SO/P hybrid ligands: an enantioselective switch in palladium-catalyzed asymmetric allylic etherifications
No full textA variety of chiral tert-butanesulfinylphosphine ligands were prepared and applied to the palladium-catalyzed asymmetric allylic etherification of 1,3-diphenylpropenyl acetate with alcohols. Excellent yields and moderate enantioselectivities were obtained. The absolute configuration of the etherification products was evidently switched only through the position change of the substituent on the P-aryl groups. (C) 2012 Elsevier Ltd. All rights reserved
MOF-derived nano CaO for highly efficient CO<sub>2</sub> fast adsorption
No full textCalcium looping is considered to be one of the best approaches for industrial CO2 high-temperature capture, whereas current CaO-based sorbent suffers poor cyclic performance, especially the relations between precursor structure and CO2 fast adsorption capacity still need to be further revealed. In this work, three calcium-based metal frameworks (Ca-MOFs) with specific structures were employed as precursors to obtain nano CaO through a two-step thermal transition process. It was found that LAC MOF-derived CaO achieved a fast adsorption capacity of 11.8 mmol g−1 (78 % of total adsorption) after 4 cycles. This was because the fiber bundle-like original LAC MOF structure changed gradually to nanosheets after 600 °C pyrolysis and finally formed regular CaO spheres with an average size of 100 nm after an 800 °C -calcination, thereby preventing further aggregation of CaO particles during the thermal transition process. In addition, the adsorption performance did not rely on pore structure, and thus pore-blocking showed little influence on the performance of CO2 capture. Hence, high stability can be achieved simply by avoiding particle sintering. The systematic study marks the significance of precise tailoring of nano-CaO for achieving the desired performance of CO2 fast adsorption.<br/
Grid load balancing using intelligent agents
No full textScalable management and scheduling of dynamic grid resources requires new technologies to build the next generation intelligent grid environments. This work demonstrates that AI techniques can be utilised to achieve effective workload and resource management. A combination of intelligent agents and multi-agent approaches is applied to both local grid resource scheduling and global grid load balancing. Each agent is a representative of a local grid resource and utilises predictive application performance data with iterative heuristic algorithms to engineer local load balancing across multiple hosts. At a higher level, agents cooperate with each other to balance workload using a peer-to-peer service advertisement and discovery mechanism
REAL-TIME GRAVITATIONAL-WAVE BURST SEARCH FOR MULTI-MESSENGER ASTRONOMY
No full text Existing observations of the universe mostly come from electromagnetic (EM) waves, representing so-called multi-wavelength astronomy. In order to enable multi-messenger astronomy, direct detection of gravitational waves (GWs) has to be processed in nearly real time. In this work, we discuss algorithm and infrastructure challenges for GW burst (GWB) search to enable multi-messenger astronomy involving GWs. A real-time computing infrastructure for LIGO (Laser Interferometer Gravitational-wave Observatory) GWB data analysis is presented, using advanced computing technologies. </jats:p
Rhodium-Catalyzed Asymmetric Addition of Arylboronic Acids to Indolylnitroalkenes
No full textIndolylnitroethanes and their derivatives are key intermediates to many bioactive structures. Most approaches to access chiral indolylnitroethanes involve organocatalyzed or metal-catalyzed asymmetric FriedelCrafts reaction of indoles with nitroalkenes. We have developed an efficient approach to optically pure a-aryl-3-indolylnitroethanes through rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to indolylnitroalkenes. Excellent yields (up to 99?%) and enantiomeric excesses (up to 99?% ee) of chiral indolylnitroethanes were achieved under mild conditions
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