11,069 research outputs found

    Lattice parameters, coefficients of thermal expansion, densities, and lattice perfection of the copper-indium primary solid solutions

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    Precise measurements of lattice parameters and densities of the alpha-phase Cu-In solid solutions were made at temperatures of 25°C. The thermal expansion coefficients between 15 and 65°C, the solid solubility of In in Cu at 650°C, and the soundness of crystal structure resulting from alloying were determined. The Cu-In alloys were prepared from high purity (99.999%) Cu and In by melting both metals inside evacuated quartz tubes. The solidified alloys were annealed and then examined by X-ray for homogeneity...The slowly solidified alpha-phase alloys gave densities lower than the theoretical (X-ray) values due to the presence of shrinkage microporosity. This density defect was found to increase with In concentration. The alloys quenched from the molten state, while still exhibiting lower density values, showed no visible porosity. However, upon annealing, voids appeared. It is very possible that the frozen-in vacancies in the quenched alloys coalesced during the prolonged heat treatment to voids visible under the optical microscope. The pores could be annihilated by plastic deformation (compression or rolling) and then the densities raised up to the theoretical. It is concluded that no structural defects (monovacancies) are formed during the cooling of Cu-In alloys, only microporosity probably due to differential shrinkage of the primary crystallization products as compared with the matrix --Abstract, Pages ii-iii

    Seebeck Coefficients in Nanoscale Junctions: Effects of Electron-vibration Scattering and Local Heating

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    We report first-principles calculations of inelastic Seebeck coefficients in an aluminum monatomic junction. We compare the elastic and inelastic Seebeck coefficients with and without local heating. In the low temperature regime, the signature of normal modes in the profiles of the inelastic Seebeck effects is salient. The inelastic Seebeck effects are enhanced by the normal modes, and further magnified by local heating. In the high temperature regime, the inelastic Seebeck effects are weakly suppressed due to the quasi-ballistic transport.Comment: 3 Figure

    Computation-Performance Optimization of Convolutional Neural Networks with Redundant Kernel Removal

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    Deep Convolutional Neural Networks (CNNs) are widely employed in modern computer vision algorithms, where the input image is convolved iteratively by many kernels to extract the knowledge behind it. However, with the depth of convolutional layers getting deeper and deeper in recent years, the enormous computational complexity makes it difficult to be deployed on embedded systems with limited hardware resources. In this paper, we propose two computation-performance optimization methods to reduce the redundant convolution kernels of a CNN with performance and architecture constraints, and apply it to a network for super resolution (SR). Using PSNR drop compared to the original network as the performance criterion, our method can get the optimal PSNR under a certain computation budget constraint. On the other hand, our method is also capable of minimizing the computation required under a given PSNR drop.Comment: This paper was accepted by 2018 The International Symposium on Circuits and Systems (ISCAS

    Variations in the Upper Paleolithic Adaptations of North China: A Review of the Evidence and Implications for the Onset of Food Production

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    The Upper Paleolithic (UP) of North China has the richest archaeological data and longest history of research in the Paleolithic archaeology of China, but there is a relative lack of systematic studies addressing human adaptations. This paper explores the spatial and temporal variability of human adaptations in terms of mobility, the key variable in the adaptive systems of hunter-gatherers. We find that before the UP, little adaptive differentiation is shown in the archaeological record of North China. The early Upper Paleolithic (EUP) is distinguished by four distinctive modes of mobility and subsistence organized roughly along lines of habitat variation. These modes persisted in the Late Upper Paleolithic (LUP), underlying the widespread prevalence of microblade technology throughout North China. This pattern significantly influenced adaptive changes during the transition from the terminal Pleistocene to early Holocene. Earliest food production emerged in hilly flank habitats where EUP mobility decreased quickly and social organization was more complex. This retrospective view of UP adaptations highlights the important role that prior conditions played at the evolutionary crossroads of prehistoric North China

    Top quark pair production at small transverse momentum in hadronic collisions

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    We investigate the transverse momentum resummation for top quark pair production at hadron colliders using the soft-collinear effective theory and the heavy-quark effective theory. We derive the factorization formula for ttˉt\bar{t} production at small pair transverse momentum, and show in detail the procedure for calculating the key ingredient of the factorization formula: the next-to-leading order soft functions. We compare our numerical results with experimental data and find that they are consistent within theoretical and experimental uncertainties. To verify the correctness of our resummation formula, we expand it to the next-to-leading order and the next-to-next-to-leading order, and compare those expressions with the exact fixed-order results numerically. Finally, using the results of transverse momentum resummation, we discuss the transverse-momentum-dependent forward-backward asymmetry at the Tevatron.Comment: 39 pages, 7 figures, 1 table; final version in PR

    Tissue manipulation using nano-particles ferrofluids for minimal access surgical applications

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    Nano-scale Iron-Oxide ferrofluids exhibit a special property, ‘superparamagnetism’, that induces an attractive force toward an external magnetic field. The aim of this project is to investigate the use of ferrofluids for tissue retraction during Minimally Access Surgery (MAS). In the in-vivo porcine experiments, 0.3 ml of ferrofluid (200 mg/ml concentration) containing 10 nm particles is injected subserosally into the small bowel, respectively. A 0.6 T magnetic field is created using a combination of 10 mm and 20 mm diameter Neodymium Iron Boron magnets. The vertical retraction distance is measured up to 80 mm and video-recorded. The results demonstrate the capacity of ferrofluid to facilitate the tissue manipulation and analysis of the migration of the particles within the tissue using micro computed tomography (CT). A theoretical model developed to validate the experimental results is also beneficial for predicting retraction force. In conclusion, this feasibility study provides a protocol for systematically using small volumes of ferrofluid, without the need to mechanically grasp the tissue

    Continuing Use of SNS Games for the Growth of Social Network Services

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    By using Social Network Services (SNSs) as platforms, game developers have gathered a huge user base, and the entertainment these games provide has further enlarged the SNS user base. However, there are signs that this symbiotic growth is slowing down. We developed a model and tested 14 hypotheses. Our main findings are: Although SNSs are “social,” “social norms” do not have much impact on the intention to use the games continually. Although users generally are not addicted to SNS games, the creation of addiction is an effective way to achieve continuance
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