14,388 research outputs found

    Performance Analysis of a Dual-Hop Cooperative Relay Network with Co-Channel Interference

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    This paper analyzes the performance of a dual-hop amplify-and-forward (AF) cooperative relay network in the presence of direct link between the source and destination and multiple co-channel interferences (CCIs) at the relay. Specifically, we derive the new analytical expressions for the moment generating function (MGF) of the output signal-to-interference-plus-noise ratio (SINR) and the average symbol error rate (ASER) of the relay network. Computer simulations are given to confirm the validity of the analytical results and show the effects of direct link and interference on the considered AF relay network

    Dirac Particles in Twisted Tubes

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    We consider the dynamics of a relativistic Dirac particle constrained to move in the interior of a twisted tube by confining boundary conditions, in the approximation that the curvature of the tube is small and slowly varying. In contrast with the nonrelativistic theory, which predicts that a particle's spin does not change as the particle propagates along the tube, we find that the angular momentum eigenstates of a relativistic spin-1/2 particle may behave nontrivially. For example, a particle with its angular momentum initially polarized in the direction of propagation may acquire a nonzero component of angular momentum in the opposite direction on turning through 2 \pi radians. Also, the usual nonrelativistic effective potential acquires an additional factor in the relativistic theory.Comment: 16 pages, 3 EPS figures, REVTeX using BoxedEPS package; email to [email protected]

    An analysis of the driving forces of energy-related carbon dioxide emissions in China’s industrial sector

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    据爱思唯尔(Elsevier)最新公布的2017年度Energy Connect China显示:2017年12月,厦门大学管理学院中国能源政策研究院院长林伯强教授为通讯作者的来自期刊Renewable and Sustainable Energy Reviews的学术论文“An analysis of the driving forces of energy-related carbon dioxide emissions in China’s industrial sector”入选爱思唯尔(Elsevier)公布的能源领域期刊中国作者高被引文章。【Abstract】Both energy consumption and the growth of carbon dioxide (CO2 ) emissions in China are attributed to the industrial sector. Energy conservation and CO2 emissions reduction in China's industrial sector is decisive for achieving a low-carbon transition. We analyze the change of energy-related CO2 emissions in China's industrial sector from 1991 to 2010 based on the Logarithmic Mean Divisia Index (LMDI) method. Results indicate that industrial activity is the major factor that contributes to the increase of industrial CO2 emissions while energy intensity is the major contributor to the decrease of CO2 emissions. Industry size shows a varying trend interchanging intervals of growth along the study period. Moreover, both energy mix and carbon intensity of energy use have negative effects on the increase of CO2 emissions. The cointegration method is adopted to further explore determinants of CO2 emissions in China's industrial sector. Results show that there exists a long-run relationship between industrial CO2 emissions and affecting factors such as CO2 emissions per unit of energy consumption, industrial value added, labor productivity and fossil fuel consumption. China's industrial CO2 emissions are mainly attributed to the coal-dominated energy structure. Policy suggestions are thus provided to reduce industrial CO2 emissions in China.The paper is supported by Newhuadu Business School Research Fund, Ministry of Education (Grant No. 10JBG013, 14YJC630026), Social Science Foundation (Grant No.12&ZD059) and National Natural Science Foundation of China (Grant No. 71472065)

    Resonance tongues and patterns in periodically forced reaction-diffusion systems

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    Various resonant and near-resonant patterns form in a light-sensitive Belousov-Zhabotinsky (BZ) reaction in response to a spatially-homogeneous time-periodic perturbation with light. The regions (tongues) in the forcing frequency and forcing amplitude parameter plane where resonant patterns form are identified through analysis of the temporal response of the patterns. Resonant and near-resonant responses are distinguished. The unforced BZ reaction shows both spatially-uniform oscillations and rotating spiral waves, while the forced system shows patterns such as standing-wave labyrinths and rotating spiral waves. The patterns depend on the amplitude and frequency of the perturbation, and also on whether the system responds to the forcing near the uniform oscillation frequency or the spiral wave frequency. Numerical simulations of a forced FitzHugh-Nagumo reaction-diffusion model show both resonant and near-resonant patterns similar to the BZ chemical system

    Long-range mechanical force in colony branching and tumor invasion

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    The most concerned factors for cancer prognosis are tumor invasion and metastasis. The patterns of tumor invasion can be characterized as random infiltration to surrounding extracellular matrix (ECM) or formation of long-range path for collective migration. Recent studies indicate that mechanical force plays an important role in tumor infiltration and collective migration. However, how tumor colonies develop mechanical interactions with each other to initiate various invasion patterns is unclear. Using a micro-patterning technique, we partition cells into clusters to mimic tumor colonies and quantitatively induce colony-ECM interactions. We find that pre-malignant epithelial cells, in response to concentrations of type I collagen in ECM ([COL]), develop various branching patterns resembling those observed in tumor invasion. In contrast with conventional thought, these patterns require long-range (~ 600 μm) transmission of traction force, but not biochemical factors. At low [COL], cell colonies synergistically develop pairwise and directed branching mimicking the formation of long-range path. By contrast, at high [COL] or high colony density, cell colonies develop random branching and scattering patterns independent of each other. Our results suggest that tumor colonies might select different invasive patterns depending on their interactions with each other and with the ECM
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