The Internet of things(IoT) as an important application of future communication networks puts a high premium on delay issues. Thus when Io T applications meet heterogeneous networks(HetNets) where macro cells are over...The Internet of things(IoT) as an important application of future communication networks puts a high premium on delay issues. Thus when Io T applications meet heterogeneous networks(HetNets) where macro cells are overlaid with small cells, some traditional problems need rethinking. In this paper, we investigate the delay-addressed association problem in two-tier Het Nets considering different backhaul technologies. Specifically, millimeter wave and fiber links are used to provide high-capacity backhaul for small cells. We first formulate the user association problem to minimize the total delay which depends on the probability of successful transmission, the number of user terminals(UTs), and the number of base stations(BSs). And then two algorithms for active mode and mixed mode are proposed to minimize the network delay. Simulation results show that algorithms based on mutual selection between UTs and BSs have better performance than those based on distance. And algorithms for mixed modes have less delay than those for active mode when the number of BSs is large enough, compared to the number of UTs.展开更多
The classical definition of learning is： change and modification of behavior as a result of experience, training, and practice. In modem technological world; this definition has been changed and modified to include t...The classical definition of learning is： change and modification of behavior as a result of experience, training, and practice. In modem technological world; this definition has been changed and modified to include the changes and modification in behavior as a result of experience, training, and practice by using modem toolkits and metacognition for self-regulated, lifelong, open, flexible, and continuous learning in Virtual Learning Environment Framework （VLEF）. The classical factors of learning included： motivation, attitude, interest, attention, readiness, participation, and reinforcement. But, due to the modem toolkits, gadgets, and ICT technologies, there are new varieties in modes of presentations and instructions. The emerging learning factors to be integrated and blended include： multimedia, hypermedia, and multimodality. The researcher has intended to identify the gap in the existing literature for the inclusion of new emerging factors such as multimedia, hypermedia, and multimodal presentations. The purpose of the study was to identify the gap in the factors of learning for learning blend in this era of science and technology, especially, in the ICT-integrated form of blended learning. The methodology of the study was analysis and synthesis of literature in the form of reviewing literature for developing a model of blended leaning. The study is significant because it has filled the gap in factors of learning for making it blended in VLEF. The factors were analyzed and synthesized in the form of a model. The findings were summarized for drawing conclusion, and at the end there were made some suggestions and recommendations for blended learning environments.展开更多
The strengths and weaknesses of different online technologies and learning methods have been examined by combining the blended learning program with practical work on institutional e-learning projects. There are diffe...The strengths and weaknesses of different online technologies and learning methods have been examined by combining the blended learning program with practical work on institutional e-learning projects. There are differences between the traditional e-learning system and the new E-Learning 2.0 training. At present time, the new technologies provided by Web 2.0 better correspond to the needs of both students and teaching staff. The new Web 2.0 allows the ＂promoting of individual creativity＂, together with the ＂use of collective intelligence＂. A comparison of the two development stages of the e-learning tools has been completed and the advantages of E-Learning 2.0 are shown. The main components of Web 2.0 are provided and the use ofwiki as an up-to-date collaboration tool for on-line teamwork is shown.展开更多
Damage tolerance of titanium alloy structures is very important for the safety of modern aircraft under complex loading and environmental conditions. However, there is no available systematic knowledge about the effec...Damage tolerance of titanium alloy structures is very important for the safety of modern aircraft under complex loading and environmental conditions. However, there is no available systematic knowledge about the effect of alloy thickness under mixed-mode loading at elevated temperatures. In the present study, a newly developed fracture experimental technique based on high-temperature moiré interferometry was employed to investigate experimentally I-II mixed-mode fracture in titanium alloy TC11 of various thicknesses at room and elevated temperatures. Compact shear specimens with thickness ranging from 1.8 to 7.1 mm were tested. The effects of temperature, thickness, and loading angle on the load capacity and crack initiation angle were investigated systematically. The TC11 alloy was shown to possess varied fracture performance at elevated tem-perature, and an opposite thickness effect at room temperature. Increasing temperature would enhance the fracture load capacity of thick specimens but reduce the fracture load capacity of thin specimens. Crack initiation angles under I-II mixed-mode loading showed the thickness-temperature coupling effects. These complex effects call for new development in three-dimensional mixed-mode fracture theory and technologies for damage tolerance assessment.展开更多
基金supported by the National Natural Science Foundation of China (NSFC) under Grants 61427801 and 61671251the Natural Science Foundation Program through Jiangsu Province of China under Grant BK20150852+3 种基金the open research fund of National Mobile Communications Research Laboratory, Southeast University under Grant 2017D05China Postdoctoral Science Foundation under Grant 2016M590481Jiangsu Planned Projects for Postdoctoral Research Funds under Grant 1501018Asupported by NSFC under Grants 61531011 and 61625106
文摘The Internet of things(IoT) as an important application of future communication networks puts a high premium on delay issues. Thus when Io T applications meet heterogeneous networks(HetNets) where macro cells are overlaid with small cells, some traditional problems need rethinking. In this paper, we investigate the delay-addressed association problem in two-tier Het Nets considering different backhaul technologies. Specifically, millimeter wave and fiber links are used to provide high-capacity backhaul for small cells. We first formulate the user association problem to minimize the total delay which depends on the probability of successful transmission, the number of user terminals(UTs), and the number of base stations(BSs). And then two algorithms for active mode and mixed mode are proposed to minimize the network delay. Simulation results show that algorithms based on mutual selection between UTs and BSs have better performance than those based on distance. And algorithms for mixed modes have less delay than those for active mode when the number of BSs is large enough, compared to the number of UTs.
文摘The classical definition of learning is： change and modification of behavior as a result of experience, training, and practice. In modem technological world; this definition has been changed and modified to include the changes and modification in behavior as a result of experience, training, and practice by using modem toolkits and metacognition for self-regulated, lifelong, open, flexible, and continuous learning in Virtual Learning Environment Framework （VLEF）. The classical factors of learning included： motivation, attitude, interest, attention, readiness, participation, and reinforcement. But, due to the modem toolkits, gadgets, and ICT technologies, there are new varieties in modes of presentations and instructions. The emerging learning factors to be integrated and blended include： multimedia, hypermedia, and multimodality. The researcher has intended to identify the gap in the existing literature for the inclusion of new emerging factors such as multimedia, hypermedia, and multimodal presentations. The purpose of the study was to identify the gap in the factors of learning for learning blend in this era of science and technology, especially, in the ICT-integrated form of blended learning. The methodology of the study was analysis and synthesis of literature in the form of reviewing literature for developing a model of blended leaning. The study is significant because it has filled the gap in factors of learning for making it blended in VLEF. The factors were analyzed and synthesized in the form of a model. The findings were summarized for drawing conclusion, and at the end there were made some suggestions and recommendations for blended learning environments.
文摘The strengths and weaknesses of different online technologies and learning methods have been examined by combining the blended learning program with practical work on institutional e-learning projects. There are differences between the traditional e-learning system and the new E-Learning 2.0 training. At present time, the new technologies provided by Web 2.0 better correspond to the needs of both students and teaching staff. The new Web 2.0 allows the ＂promoting of individual creativity＂, together with the ＂use of collective intelligence＂. A comparison of the two development stages of the e-learning tools has been completed and the advantages of E-Learning 2.0 are shown. The main components of Web 2.0 are provided and the use ofwiki as an up-to-date collaboration tool for on-line teamwork is shown.
基金supported by the Natural Science Foundation of Jiangxi Province of China (Grant No. 2009GZW0022)
文摘Damage tolerance of titanium alloy structures is very important for the safety of modern aircraft under complex loading and environmental conditions. However, there is no available systematic knowledge about the effect of alloy thickness under mixed-mode loading at elevated temperatures. In the present study, a newly developed fracture experimental technique based on high-temperature moiré interferometry was employed to investigate experimentally I-II mixed-mode fracture in titanium alloy TC11 of various thicknesses at room and elevated temperatures. Compact shear specimens with thickness ranging from 1.8 to 7.1 mm were tested. The effects of temperature, thickness, and loading angle on the load capacity and crack initiation angle were investigated systematically. The TC11 alloy was shown to possess varied fracture performance at elevated tem-perature, and an opposite thickness effect at room temperature. Increasing temperature would enhance the fracture load capacity of thick specimens but reduce the fracture load capacity of thin specimens. Crack initiation angles under I-II mixed-mode loading showed the thickness-temperature coupling effects. These complex effects call for new development in three-dimensional mixed-mode fracture theory and technologies for damage tolerance assessment.
