Pressure drop and compound heat transfer characteristics of a converging-diverging tube with evenly spaced twisted-tapes （CD-T tube） have been investigated experimentally. Swirl was generated by evenly spaced twiste...Pressure drop and compound heat transfer characteristics of a converging-diverging tube with evenly spaced twisted-tapes （CD-T tube） have been investigated experimentally. Swirl was generated by evenly spaced twisted-tape elements which vary in twist ratio and rotation angle. Space ratio also has an important effect on the characteristics. For comparison, experiments in a smooth circular tube and a converging-diverging （CD） tube with-out twisted-tapes were carried out. The results show that the twisted-tape with twist ratio y=4.72 and rotation angle θ=180° has the best performance among the four types of twisted-tapes presented in this paper. At Reynolds number ranging from 3400 to 20000, when space ratio s=48.6, the heat transfer efficiency index, which increases as the Reynolds number increases, is 0.85-1.21 and 1.07-1.15 compared to that of a smooth circular tube and a CD tube without twisted-tape inserts, respectively.展开更多
Objective To determine whether the convergences of tactile information also occur at thalamic ventroposterolateral nucleus in rats, we investigated the properties of tactile responses of the thalamic ventroposterolate...Objective To determine whether the convergences of tactile information also occur at thalamic ventroposterolateral nucleus in rats, we investigated the properties of tactile responses of the thalamic ventroposterolateral nucleus in rats. Methods Unit responses were recorded extracellularly from thalamic ventroposterolateral nucleus in anesthetized rats. Results Among 156 neurons examined, 140 neurons （89.7%） had the single, continual and small receptive fields, and 16 neurons （10.3%） had two discrete receptive fields. Some neurons exhibited different responses to the same intensity stimulation which delivered to different points in their receptive fields. In addition, 4.5% neurons （n -- 7） responded only to locomotive stimulation but not to a punctiform tactile stimulation. Conclusion The majority of neurons in ventroposterolateral nucleus of rats have the spatial, temporal and submodal characteristics of cutaneous receptors, while the minority of neurons exhibit the responses of interaction of different peripheral receptors. Therefore, it is con- cluded that there are convergences of tactile information at the ventroposterolateral nucleus of rats.展开更多
A key solution to urban and global sustainability is effective planning of sustainable urban development, for which geo-techniques especially cellular automata(CA) models can be very informative. However, existing CA ...A key solution to urban and global sustainability is effective planning of sustainable urban development, for which geo-techniques especially cellular automata(CA) models can be very informative. However, existing CA models for simulating sustainable urban development, though increasingly refined in modeling urban growth, capture mostly the environmental aspect of sustainability. In this study, an adaptable risk-constrained CA model was developed by incorporating the social-ecological risks of urban development. A three-dimensional risk assessment framework was proposed that explicitly considers the environmental constraints on, system resilience to, and potential impacts of urban development. The risk-constrained model was then applied to a case study of Sheyang County, Jiangsu Province in the eastern China. Comparative simulations of urban development in four contrasting scenarios were conducted, namely, the environmental suitability constrained scenario, the ecological risk constrained scenario, the social risk constrained scenario, and the integrated social-ecological risk constrained scenario. The simulations suggested that considering only environmental suitability in the CA simulation of urban development overestimated the potential of sustainable urban growth, and that the urbanization mode changed from city expansion that was more constrained by social risks to town growth that was more constrained by ecological risks. Our risk-constrained CA model can better simulate sustainable urban development; additionally, we provide suggestions on the sustainable urban development in Sheyang and on future model development.展开更多
Joint mode selection and link allocation are crucial to achieve the advantage of Device-to-Device(D2 D) communications in improving spectral efficiency. In practice, cellular users tend to not be totally altruistic or...Joint mode selection and link allocation are crucial to achieve the advantage of Device-to-Device(D2 D) communications in improving spectral efficiency. In practice, cellular users tend to not be totally altruistic or absolutely selfish. How to stimulate them to devote their links and how to allocate their links to D2 D pair candidates efficiently are two main challenges. In this paper, we encourage cellular users through the variable payment with regard to the social tie strength between cellular users and D2 D pair candidates. In particular, the social tie strength is inferred through a graph inference model and its impact on the payment is quantified as a negative exponential function. Then, we propose a resource scheduling optimization model based on the non-transferable utility coalition formation game, and a distributed coalition formation algorithm based on the Pareto preference and merge-and-split rule. From them, the final coalition structure is obtained, which reflects the strategy of mode selection and link allocation. Numerical results are presented to verify the effectiveness of our proposed scheme.展开更多
Many classical clustering algorithms do good jobs on their prerequisite but do not scale well when being applied to deal with very large data sets(VLDS).In this work,a novel division and partition clustering method(DP...Many classical clustering algorithms do good jobs on their prerequisite but do not scale well when being applied to deal with very large data sets(VLDS).In this work,a novel division and partition clustering method(DP) was proposed to solve the problem.DP cut the source data set into data blocks,and extracted the eigenvector for each data block to form the local feature set.The local feature set was used in the second round of the characteristics polymerization process for the source data to find the global eigenvector.Ultimately according to the global eigenvector,the data set was assigned by criterion of minimum distance.The experimental results show that it is more robust than the conventional clusterings.Characteristics of not sensitive to data dimensions,distribution and number of nature clustering make it have a wide range of applications in clustering VLDS.展开更多
基金Supported by the State Key Development Program for Basic Research of China （No.G2000263001） and the National Natural Science Foundation of China （No.20776046）.
文摘Pressure drop and compound heat transfer characteristics of a converging-diverging tube with evenly spaced twisted-tapes （CD-T tube） have been investigated experimentally. Swirl was generated by evenly spaced twisted-tape elements which vary in twist ratio and rotation angle. Space ratio also has an important effect on the characteristics. For comparison, experiments in a smooth circular tube and a converging-diverging （CD） tube with-out twisted-tapes were carried out. The results show that the twisted-tape with twist ratio y=4.72 and rotation angle θ=180° has the best performance among the four types of twisted-tapes presented in this paper. At Reynolds number ranging from 3400 to 20000, when space ratio s=48.6, the heat transfer efficiency index, which increases as the Reynolds number increases, is 0.85-1.21 and 1.07-1.15 compared to that of a smooth circular tube and a CD tube without twisted-tape inserts, respectively.
文摘Objective To determine whether the convergences of tactile information also occur at thalamic ventroposterolateral nucleus in rats, we investigated the properties of tactile responses of the thalamic ventroposterolateral nucleus in rats. Methods Unit responses were recorded extracellularly from thalamic ventroposterolateral nucleus in anesthetized rats. Results Among 156 neurons examined, 140 neurons （89.7%） had the single, continual and small receptive fields, and 16 neurons （10.3%） had two discrete receptive fields. Some neurons exhibited different responses to the same intensity stimulation which delivered to different points in their receptive fields. In addition, 4.5% neurons （n -- 7） responded only to locomotive stimulation but not to a punctiform tactile stimulation. Conclusion The majority of neurons in ventroposterolateral nucleus of rats have the spatial, temporal and submodal characteristics of cutaneous receptors, while the minority of neurons exhibit the responses of interaction of different peripheral receptors. Therefore, it is con- cluded that there are convergences of tactile information at the ventroposterolateral nucleus of rats.
基金Under the auspices of the Special Research Funds for Public Welfare,Ministry of Land and Resources of China(No.201511001-03)the Open Fund of Key Laboratory of Coastal Zone Exploitation and Protection,Ministry of Land and Resource of China(No.2017CZEPK03)
文摘A key solution to urban and global sustainability is effective planning of sustainable urban development, for which geo-techniques especially cellular automata(CA) models can be very informative. However, existing CA models for simulating sustainable urban development, though increasingly refined in modeling urban growth, capture mostly the environmental aspect of sustainability. In this study, an adaptable risk-constrained CA model was developed by incorporating the social-ecological risks of urban development. A three-dimensional risk assessment framework was proposed that explicitly considers the environmental constraints on, system resilience to, and potential impacts of urban development. The risk-constrained model was then applied to a case study of Sheyang County, Jiangsu Province in the eastern China. Comparative simulations of urban development in four contrasting scenarios were conducted, namely, the environmental suitability constrained scenario, the ecological risk constrained scenario, the social risk constrained scenario, and the integrated social-ecological risk constrained scenario. The simulations suggested that considering only environmental suitability in the CA simulation of urban development overestimated the potential of sustainable urban growth, and that the urbanization mode changed from city expansion that was more constrained by social risks to town growth that was more constrained by ecological risks. Our risk-constrained CA model can better simulate sustainable urban development; additionally, we provide suggestions on the sustainable urban development in Sheyang and on future model development.
基金supported by Natural Science Foundations of China (No. 61671474)Jiangsu Provincial Natural Science Foundation for Excellent Young Scholars (No. BK20170089)
文摘Joint mode selection and link allocation are crucial to achieve the advantage of Device-to-Device(D2 D) communications in improving spectral efficiency. In practice, cellular users tend to not be totally altruistic or absolutely selfish. How to stimulate them to devote their links and how to allocate their links to D2 D pair candidates efficiently are two main challenges. In this paper, we encourage cellular users through the variable payment with regard to the social tie strength between cellular users and D2 D pair candidates. In particular, the social tie strength is inferred through a graph inference model and its impact on the payment is quantified as a negative exponential function. Then, we propose a resource scheduling optimization model based on the non-transferable utility coalition formation game, and a distributed coalition formation algorithm based on the Pareto preference and merge-and-split rule. From them, the final coalition structure is obtained, which reflects the strategy of mode selection and link allocation. Numerical results are presented to verify the effectiveness of our proposed scheme.
基金Projects(60903082,60975042)supported by the National Natural Science Foundation of ChinaProject(20070217043)supported by the Research Fund for the Doctoral Program of Higher Education of China
文摘Many classical clustering algorithms do good jobs on their prerequisite but do not scale well when being applied to deal with very large data sets(VLDS).In this work,a novel division and partition clustering method(DP) was proposed to solve the problem.DP cut the source data set into data blocks,and extracted the eigenvector for each data block to form the local feature set.The local feature set was used in the second round of the characteristics polymerization process for the source data to find the global eigenvector.Ultimately according to the global eigenvector,the data set was assigned by criterion of minimum distance.The experimental results show that it is more robust than the conventional clusterings.Characteristics of not sensitive to data dimensions,distribution and number of nature clustering make it have a wide range of applications in clustering VLDS.
