46,500 research outputs found
Numerical analysis of confined flow past permeable square cylinder with CE/SE method
No full textThe unsteady flow field past a two-dimensional permeable square cylinder was predicted by an updated CE/SE method. The periodic patterns of streamline and vortex shedding were obtained. The evolution of lift and drag coefficients were analysed. Results of 2D computations were compared with the experimental data. It found that the Reynolds number dominated the magnitude and frequency of the vorticity given porosity and Darcy number. It proved that the CE/SE method was an effective tool for predicting viscous flows in porous media
Magnetic hardening of Nd-Ce-Fe-B films with high Ce concentration
No full textPartial substitution of Ce in Nd-Fe-B magnets is a feasible way to cope with the crisis of Nd and Dy in Nd-Fe-B production and reduce the cost of Nd-Fe-B magnets. In the present paper, the Nd-Ce-Fe-B films with high performance have been successfully fabricated by using an ultra-high vacuum (UHV) magnetron sputtering system. High magnetic performance with a ceorcivity of 13.3 kOe, a remanence of 11.4 kGs and a maximum energy product of 29.4 GMOe is obtained with the Ce substitution for more than 50 wt.% Nd without Dy addition. The high coercivity and (BH) max achieved in this work are much larger than those of previously reported Nd-Ce-Fe-B magnets with the same Ce concentration. The phase structure, microstructure and coercivity mechanism are analyzed. The coercivity mechanism is determined to be mainly dominated by nucleation. Based on the microstructure observation and coercivity mechanism analysis, the fine and well separated grains, smooth grain surface, small and less inhomogeneities should be responsible for the high coercivity. Our results encourage the further improvement of magnetic properties in Ce magnets including the bulk material with high Ce concentration
An improved CE/SE scheme for incompressible multiphase flows and its applications
No full textA new space-time conservation element-solution element (CE/SE) scheme, which is based on the hexahedron mesh, is proposed by constructing a new structure of solution elements (SEs) and conservation elements (CEs) and extended to two-dimensional incompressible multiphase flows. This scheme is applied to several incompressible flow problems, such as lid-driven cavity flow, dam break flow, motions of falling droplets, flow instability and water-kerosene interaction. The numerical results and their comparison with lecture results and experimental data are presented. The comparisons demonstrate that the computational scheme developed currently is clear in physical concept, easy to be implemented and highly accurate and efficient for the above-mentioned problems. The highlight is that the pretreatment method is proposed, transforming the elliptic-parabolic equations to the hyperbolic equations, which can be directly simulated by the improved CE/SE scheme. Thus, the improved CE/SE scheme can be applied to incompressible multiphase flows widely
Special issue: Process safety in times of a pandemic
No full textGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Safety and Security Scienc
Investigation of dual-ported shroud casing in a centrifugal compressor: aerodynamic performance and aeroacoustics
No full textThe dual-ported shroud casing has two ports over the impeller section in a centrifugal compressor, different from the traditional ported shroud casing. This paper uses numerical simulations and experiments to investigate the effects of the dual-ported shroud on the centrifugal compressor, including aerodynamic performance and aeroacoustics. According to the experimentally measured compressor performance map, the novel finding is that the dual-port casing treatment extends the compressor operating range by improving the instability margin and increasing the compressor choke flow capacity. The mechanism contributing to the choke flow capacity increase is the bypass function. The dual-ported shroud casing bypasses a part of the air to enter the impeller channels at the blade tips without going through the impeller geometry throat. Besides the benefits, the efficiency and aero-acoustic measurements identify the disadvantages of the dual-ports casing treatment: the peak efficiency deterioration at high rotational speeds and louder noise emission at the compressor inlet
Distributed human computation framework for linked data co-reference resolution
No full textDistributed Human Computation (DHC) is a technique used to solve computational problems by incorporating the collaborative effort of a large number of humans. It is also a solution to AI-complete problems such as natural language processing. The Semantic Web with its root in AI is envisioned to be a decentralised world-wide information space for sharing machine-readable data with minimal integration costs. There are many research problems in the Semantic Web that are considered as AI-complete problems. An example is co-reference resolution, which involves determining whether different URIs refer to the same entity. This is considered to be a significant hurdle to overcome in the realisation of large-scale Semantic Web applications. In this paper, we propose a framework for building a DHC system on top of the Linked Data Cloud to solve various computational problems. To demonstrate the concept, we are focusing on handling the co-reference resolution in the Semantic Web when integrating distributed datasets. The traditional way to solve this problem is to design machine-learning algorithms. However, they are often computationally expensive, error-prone and do not scale. We designed a DHC system named iamResearcher, which solves the scientific publication author identity co-reference problem when integrating distributed bibliographic datasets. In our system, we aggregated 6 million bibliographic data from various publication repositories. Users can sign up to the system to audit and align their own publications, thus solving the co-reference problem in a distributed manner. The aggregated results are published to the Linked Data Cloud
Intersystem soft handover for converged DVB-H and UMTS networks
No full textDigital video broadcasting for handhelds (DVB-H) is the standard for broadcasting Internet Protocol (IP) data services to mobile portable devices. To provide interactive services for DVB-H, the Universal Mobile Telecommunications System (UMTS) can be used as a terrestrial interaction channel for the unidirectional DVB-H network. The converged DVB-H and UMTS network can be used to address the congestion problems due to the limited multimedia channel accesses of the UMTS network. In the converged network, intersystem soft handover between DVB-H and UMTS is needed for an optimum radio resource allocation, which reduces network operation cost while providing the required quality of service. This paper deals with the intersystem soft handover between DVB-H and UMTS in such a converged network. The converged network structure is presented. A novel soft handover scheme is proposed and evaluated. After considering the network operation cost, the performance tradeoff between the network quality of service and the network operation cost for the intersystem soft handover in the converged network is modeled using a stochastic tree and analyzed using a numerical simulation. The results show that the proposed algorithm is feasible and has the potential to be used for implementation in the real environment
Beyond interfaces: A usability study of Chinese journal databases
No full textA presentation at the Council on East Asian Libraries (CEAL) annual meeting in Boston, MA on March 21, 2007
Rose Galaida and the Central China Relief Records, 1946: Discovery, Investigation, and Implications
No full textThe materials in the Central China Relief Records (CCRR) collection provide a window to the experiences of Rose Galaida in Hubei. The collection consists of about 100 documents totaling over 300 pages (excluding duplicate copies) and 5 photographs.Peer reviewedPublished in the Journal of East Asian Libraries and available from the journal at: https://scholarsarchive.byu.edu/jeal/vol2011/iss153/
Breaking New Ground in East Asia Library History
No full textReview of Peter X. Zhou. Collecting Asia: East Asian Libraries in North America (2010).Published in H-Net Reviews in the Humanities and Social Sciences and available at: http://www.h-net.org/reviews/showrev.php?id=32231March 201
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