5G Based on Cognitive Radio

Both the cognitive radio (CR) and the fifth generation of cellular wireless standards (5G) are considered to be the future technologies: on one hand, CR offers the possibility to significantly increase the spectrum efficiency, by smart secondary users (CR users) using the free licensed users spectrum holes; on the other hand, the 5G implies the whole wireless world interconnection (WISDOM—Wireless Innovative System for Dynamic Operating Megacommunications concept), together with very high data rates Quality of Service (QoS) service applications. In this paper, they are combined together into a “CR based 5G”. With this aim, two novel ideas are advanced: the 5G terminal is a CR terminal and the CR technology is chosen for WISDOM concept. Thus, the 5G takes CR flexibility and adaptability and makes the first step through a commercial and tangible form.     

A Distributed Energy-Aware Routing Protocol for Underwater Wireless Sensor Networks

The design of routing protocols for Underwater Wireless Sensor Networks (UWSNs) poses many challenges due to the intrinsic properties of underwater environments. In this paper we present DUCS (Distributed Underwater Clustering Scheme), a new GPS-free routing protocol that does not use flooding techniques, minimizes the proactive routing message exchange and uses data aggregation to eliminate redundant information. Besides, DUCS assumes random node mobility and compensates the high propagation delays of the underwater medium using a continually adjusted timing advance combined with guard time values to minimize data loss. The theoretical and simulation studies carried out demonstrate its effectiveness.     

Aggregation convergecast scheduling in wireless sensor networks

We consider the problem of scheduling in wireless sensor networks for the purposes of aggregation convergecast. We observe that existing schemes adopt essentially a two phase approach, consisting of, first, a tree construction and, second, a scheduling phase. Following a similar approach, we propose two new improvements, one to each of the two phases. Starting with a new lower bound on the schedule length, we make use of it in the tree construction phase. The tree construction phase consists of solutions to instances of bipartite graph semi-matchings. The scheduling phase is a weight-based priority scheme that obeys dependency (tree) and interference constraints. Our extensive experiments show that, overall, our proposed solution not only outperforms all previously proposed solutions in terms of schedule length, but it also significantly extends the network’s lifetime.     

Towards the realistic planning of GMPLS-based optical transport networks

The multi-granular switching concept defined in Generalized Multiprotocol Label Switching (GMPLS) is expected to be a future-proof solution for mitigating the Optical Crossconnet scalability problems associated with the skyrocketing growth of traffic in optical transport networks. In this paper, we address the problem of planning the GMPLS-based (or multi-granular) transport network with color (or label) conversion and signal regeneration capabilities. The objective of the problem is to minimize the total weighted port count in the transport network. The novelty of this problem lies in the incorporation of the following for the first time: (1) considering all traffic granularities defined in GMPLS; (2) allowing wavelength, waveband, and fiber conversions; (3) considering the optical-reach limitation of optical signals; and (4) customizing the optical reach of all-optical paths. Due to the computational complexity of the problem, we propose various efficient heuristics that are capable of solving large-sized problems in a reasonable amount of time. In order to achieve the best possible solution to the planning problem, a comprehensive evaluation of different heuristic variations through illustrative examples and simulations is conducted. The results also provide valuable insights into many issues that can contribute to further research and development in this area.     

Topology aggregation and decoding algorithms based on a minimum spanning tree in asymmetric multi-domain optical networks

In an optical network, the connections are generally bidirectional, but their QoS parameters in each direction may be not the same. In this paper, we propose an enhanced algorithm called Node Label Order First (NLOF), which can maintain asymmetrical information and guarantee availability of the compressed topology. Besides, a decoding algorithm to restore the compressed topology named Average Proportional point (AP) is also proposed, which not only retains the space complexity of the aggregation process but also improves the accuracy of the restored information. Simulation results show that combing NLOF with AP can balance the contradiction between space complexity of the aggregation algorithm and routing accuracy.     

Finite Element Method Analysis of the Cutoff Wavelength of Dominant Mode in Unilateral Finline

The cutoff wavelength of dominant mode in unilateral finline is analyzed by finite element method. The cutoff wavelength can be changed by adjusting the thickness of metallic fins and dielectric constant of dielectric substrate. Numerical results provide in this paper have important values in practical applications.     

The effect of drying method on the properties and nanoscale structure of cellulose whiskers

Cellulose whiskers were prepared from wood- and cotton-based microcrystalline cellulose and dried by two methods: freeze-drying or air-drying. The effect of drying method on the properties and structure of the whiskers were studied. Furthermore, the influence of the source of cellulose on the nanoscale structure was investigated. Drying method was observed to slightly influence the thermal stability of cellulose whiskers, whereas the char residue varied significantly depending on the drying process performed. Small- and wide-angle X-ray scattering and solid state nuclear magnetic resonance spectroscopy were used to examine the crystallinity and nanoscale structure of the dried whiskers. It was observed that the crystal structure and crystallinity of cellulose whiskers remained during all treatments, whereas their nanoscale structure was significantly influenced by drying method, neutralization, and source of cellulose. Relationships between thermal behavior and nanoscale structure were reported and discussed.     

DSC study of stabilizing effect of antioxidant mixtures in styrene-butadiene rubber

The type of cooperation between antioxidants in the binary mixtures of four substituted diphenylamines and phenotiazine in the stabilization of styrene-butadiene rubber has been tested. Thermooxidation of the samples has been studied by differential scanning calorimetry under non-isothermal conditions. The protection factors of the individual stabilizers and their mixtures were determined. The synergy factors were applied to asses the type of cooperation of antioxidants in the mixtures. From their values it can be concluded that the type of cooperation depends on temperature. The highest synergistic effect has been observed for the mixture of phenotiazine and [4-(1-methyl-1-phenyl-ethyl)-phenyl]-phenylamine.     

Numerical simulation for the temperature changing rule of the crude oil in a storage tank based on the wavelet finite element method

In order to study the temperature changing rule of the crude oil in the storage tank, the wavelet finite element method, the traditional finite element method and the test were used to carry out the numerical simulation. Firstly, the thermal wavelet finite element was put forward established based on thermal finite element theory and the wavelet theory. And the computational model and three boundary conditions were established. And then the temperature changing rule of the crude oil in the storage tank in 24 h for three boundary conditions was obtained by using three methods, and the results showed that the wavelet finite element method had advantages in the numerical analysis of the temperature changing rule of the crude oil in the storage. And then the temperature distribution rule of the crude oil in the storage tank under different conditions in 5 h was obtained. And the temperature changing mechanism of the crude oil was summarized finally.