Research on trust model in container-based cloud service

Container virtual technology aims to provide program independence and resource sharing. The container enables flexible cloud service. Compared with traditional virtualization, traditional virtual machines have difficulty in resource and expense requirements. The container technology has the advantages of smaller size, faster migration, lower resource overhead, and higher utilization. Within container-based cloud environment, services can adopt multi-target nodes. This paper reports research results to improve the traditional trust model with consideration of cooperation effects. Cooperation trust means that in a container-based cloud environment, services can be divided into multiple containers for different container nodes. When multiple target nodes work for one service at the same time, these nodes are in a cooperation state. When multi-target nodes cooperate to complete the service, the target nodes evaluate each other. The calculation of cooperation trust evaluation is used to update the degree of comprehensive trust. Experimental simulation results show that the cooperation trust evaluation can help solving the trust problem in the container-based cloud environment and can improve the success rate of following cooperation

Life cycle greenhouse gas emissions of multi-pathways natural gas vehicles in china considering methane leakage

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordNatural gas has been promoted rapidly recent years to substitute traditional vehicle fuels. However, methane leakages in the natural gas supply chains make it difficult to ascertain whether it can reduce greenhouse gas emissions when used as a transport fuel. This paper characterizes the natural gas supply chains and their segments involved, estimates the venting and fugitive leakages from natural gas supply chains, decides the distribution among segments and further integrates it with life cycle analysis on natural gas fueled vehicles. Domestic natural gas supply chain turns out to be the dominant methane emitter, accounting for 67% of total methane leakages from natural gas supply chains. Transportation segments contribute 42–86% of the total methane leakages in each supply chain, which is the greatest contribution among all the segments. Life cycle analysis on private passenger vehicles, transit buses and heavy-duty trucks show that compressed natural gas and liquefied natural gas bring approximately 11–17% and 9–15% greenhouse gas emission reduction compared to traditional fossil fuels, even considering methane leaks in the natural gas supply chains. Methane leakages from natural gas supply chains account for approximately 2% of the total life cycle greenhouse gas emissions of natural gas vehicles. The results ascertain the low-carbon attribute of natural gas, and greater efforts should be exerted to promote natural gas vehicles to help reduce greenhouse gas emissions from on-road transportation.National Natural Science Foundation of ChinaInternational Science & Technology Cooperation Program of Chin

A Signal-Space Aligned Network Coding Approach to Distributed MIMO

© 2016 IEEE. This paper studies an uplink distributed MIMO (DMIMO) system that consists of $K$ users and K distributed base stations (BSs), where the BSs are connected to a central unit (CU) via independent rate-constrained backhaul (BH) links. We propose a new signal-space aligned network coding scheme. First, a network coding generator matrix is selected subject to certain structural properties. Next, distributed linear precoding is employed by the users to create aligned signal-spaces at the BSs, according to the pattern determined by the network coding generator matrix. For each aligned signal-space at a BS, physical-layer network coding is utilized to compute the corresponding network-coded (NC) messages, where the actual number of NC messages forwarded to the CU is determined by the BH rate-constraint. We derive an achievable rate of the proposed scheme based on the existence of the NC generator matrix and signal-space alignment precoding matrices. For DMIMO with two and three BSs, the achievable rates and degrees of freedom (DoF) are evaluated and shown to outperform existing schemes. For example, for DMIMO with two BSs where each user and BS have N and N antennas, respectively, the proposed scheme achieves a DoF of 2 min N,N-1, if the BH capacity scales like 2 min (N,N-1) log SNR. This leads to greater DoF compared to that utilizes the strategy for interference channel, whose DoF is min (N,N right). Numerical results demonstrate the performance advantage of the proposed scheme

Numerical Study on Indoor Wideband Channel Characteristics with Different Internal Wall

Effects of material and configuration of the internal wall on the performance of wideband channel are investigated by using the Finite Difference Time-Domain (FDTD) method. The indoor wideband channel characteristics, such as the path-loss, Root-Mean-Square (RMS) delay spread and number of the multipath components (MPCs), are presented. The simulated results demonstrate that the path-loss and MPCs are affected by the permittivity, dielectric loss tangent and thickness of the internal wall, while the RMS delay spread is almost not relevant with the dielectric permittivity. Furthermore, the comparison of simulated result with the measured one in a simple scenario has validated the simulation study