7,657 research outputs found
Gluon saturation and pseudo-rapidity distributions of charged hadrons at RHIC energy regions
We modified the gluon saturation model by rescaling the momentum fraction
according to saturation momentum and introduced the Cooper-Frye hydrodynamic
evolution to systematically study the pseudo-rapidity distributions of final
charged hadrons at different energies and different centralities for Au-Au
collisions in relativistic heavy-ion collisions at BNL Relativistic Heavy Ion
Collider (RHIC). The features of both gluon saturation and hydrodynamic
evolution at different energies and different centralities for Au-Au collisions
are investigated in this paper.Comment: 14 pages, 4 figure
Geochemistry of reduced inorganic sulfur, reactive iron, and organic carbon in fluvial and marine surface sediment in the Laizhou Bay region, China
Understanding the geochemical cycling of sulfur in sediments is important because it can have implications for both modern environments (e.g., deterioration of water quality) and interpretation of the ancient past (e.g., sediment C/S ratios can be used as indicators of palaeodepositional environment). This study investigates the geochemical characteristics of sulfur, iron, and organic carbon in fluvial and coastal surface sediments of the Laizhou Bay region, China. A total of 63 sediment samples were taken across the whole Laizhou Bay marine region and the 14 major tidal rivers draining into it. Acid volatile sulfur, chromium (II)-reducible sulfur and elemental sulfur, total organic carbon, and total nitrogen were present in higher concentrations in the fluvial sediment than in the marine sediment of Laizhou Bay. The composition of reduced inorganic sulfur in surface sediments was dominated by acid volatile sulfur and chromium (II)-reducible sulfur. In fluvial sediments, sulfate reduction and formation of reduced inorganic sulfur were controlled by TOC and reactive iron synchronously. High C/S ratios in the marine sediments indicate that the diagenetic processes in Laizhou Bay have been affected by rapid deposition of sediment from the Yellow River in recent decades
Optimal Beamforming for Physical Layer Security in MISO Wireless Networks
A wireless network of multiple transmitter-user pairs overheard by an
eavesdropper, where the transmitters are equipped with multiple antennas while
the users and eavesdropper are equipped with a single antenna, is considered.
At different levels of wireless channel knowledge, the problem of interest is
beamforming to optimize the users' quality-of-service (QoS) in terms of their
secrecy throughputs or maximize the network's energy efficiency under users'
QoS. All these problems are seen as very difficult optimization problems with
many nonconvex constraints and nonlinear equality constraints in beamforming
vectors. The paper develops path-following computational procedures of
low-complexity and rapid convergence for the optimal beamforming solution.
Their practicability is demonstrated through numerical examples
Exploiting latent relevance for relational learning of ubiquitous things
With recent advances in radio-frequency identification(RFID), wireless sensor networks, andWeb services, physical things are becoming an integral part of the emerging ubiquitous Web. While this integration offers many exciting opportunities such as efficient supply chains and improved environmental monitoring, it also presents many significant challenges. One such challenge lies in how to classify, discover, and manage ubiquitous things, which is critical for efficient and effective object search, recommendation, and composition. In this paper, we focus on automatically classifying ubiquitous things into manageable semantic category labels by exploiting the information hidden in interactions between users and ubiquitous things. We develop a novel approach to extract latent relevances by building a relational network of ubiquitous things (RNUbiT) where similar things are linked via virtual edges according to their latent relevances. A discriminative learning algorithm is also developed to automatically determine category labels for ubiquitous things. We conducted experiments using real-world data and the experimental results demonstrate the feasibility and validity of our proposed approach.Lina Yao and Quan Z. Shen
Cloud Armor: a platform for credibility-based trust management of cloud services
Trust management of cloud services is emerging as an impor- tant research issue in recent years, which poses signicant challenges because of the highly dynamic, distributed, and non-transparent nature of cloud services. This paper de- scribes Cloud Armor, a platform for credibility-based trust management of cloud services. The platform provides a crawler for automatic cloud services discovery, an adaptive and robust credibility model for measuring the credibility of feedbacks, and a trust-based recommender to recommend the most trustworthy cloud services to users. This paper presents the motivation, system design, implementation, and a demonstration of the Cloud Armor platform.Talal H. Noor, Quan Z. Sheng, Anne H.H. Ngu, Abdullah Alfazi and Jeriel Lawhttp://www.cikm2013.org/cfp.ph
Study on thermal conductivity of gas phase in nano-porous aerogel
This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Nano-porous aerogel has an ultra low thermal conductivity and is usually used as the super
insulator. To evaluate the insulation performance of the aerogel, we focus on studying the thermal
conductivity of gas phase in the aerogel. We present a modified model to take into account the effect of nonuniform
pore-size distribution on the gaseous thermal conductivity, and the present model predicts more
agreement results with available data than the existing models. The gaseous thermal conductivity of the
aerogel at high temperature gradient condition is also numerically studied. We also study the effect of the
thermal transpiration flow on the gaseous thermal conductivity, and the results shows that the thermal
transpiration flow effect leads to a reduction of the gaseous thermal conductivity
On the onset of surface condensation: formation and transition mechanisms of condensation mode
Financial supports from the National Natural Science Foundation of China (51406205), the Beijing Natural Science Foundation (3142021), China Scholarship Council Ph. D studentship and the Engineering and Physical Sciences Research Council (EPSRC) of the UK through research grant (EP/L001233/1) are acknowledged
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