Swarm Intelligent Compressive Routing in Wireless Sensor Networks

This article proposes a novel algorithm to improve the lifetime of a wireless sensor network. This algorithm employs swarm intelligence algorithms in conjunction with compressive sensing theory to build up the routing trees and to decrease the communication rate. The main contribution of this article is to extend swarm intelligence algorithms to build a routing tree in such a way that it can be utilized to maximize efficiency, thereby rectifying the delay problem of compressive sensing theory and improving the network lifetime. In addition, our approach offers accurate data recovery from small amounts of compressed data. Simulation results show that our approach can effectively extend the network lifetime of a large‐scale wireless sensor network.     

Mortality response of folate receptor-activated,PEG–functionalized TiO2 nanoparticles for doxorubicin loading with and without ultraviolet irradiation

TiO₂ nanoparticles (NPs) were synthesized by hydrothermal assisted sol–gel technique. In the next step, as-synthesized NPs were modified by poly ethylene glycol (PEG). Then, folic acid (FA) was conjugated to TiO₂–PEG. Finally, Doxorubicin (Dox) as an anticancer drug was loaded on as-prepared TiO₂–PEG–FA nanocarrier. The optimization of TiO₂ and FA concentration and the influence of ultraviolet (UV) irradiation on photocatalytic activity of nanocarrier and Dox loaded carrier were assessed by utilizing the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT)-assay method.     

Comparison of the Activation Energies of the Formation of Chromium Carbide Coating on Carburized and Uncarburized AISI 1020 Steel

Chromium carbide coatings deposited by the salt bath method have a lot of technologically interesting characteristics. This method produces hard, wear–resistant, oxidation and corrosion–resistant coating layers on steel substrates. In the present study, the kinetics of chromium carbide formation on carburized and uncarburized AISI 1020 steel substrates has been compared. The presence of the Cr₇C₃ phase on the surface of steel substrates was confirmed by X‐ray diffraction. Cross–sectional observation of optical and SEM images showed that chromium carbide layers formed on the steel substrates were rather compact and smooth. The kinetics of chromium carbide coating by salt bath immersion indicated a parabolic relationship between carbide layer thickness and treatment time. The activation energy of the formation of carbide on the surface of carburized and uncarburized steel was calculated to be 87.9 and 225.6 kJ/mol, respectively. Moreover, an attempt was made to present contour diagrams for predicting the thickness of the chromium carbide layer. In addition, the possibility of establishing and using some mathematical relationships between process parameters and chromium carbide layer thickness was investigated.     

A CUSUM-based method for monitoring simple linear profiles

In most statistical process control applications, the quality of a process or product is characterized by univariate or multivariate quality characteristics and monitored by the corresponding univariate and multivariate control charts, respectively. However, sometimes, the quality of a process or a product is better characterized by a relationship between a response variable and one or more explanatory variables. This relationship, which can be linear, nonlinear, or even a complicated model, is referred to as a profile. So far, several methods have been proposed for monitoring simple linear profiles. In this paper, a new method based on cumulative sum statistics is proposed to enhance monitoring of linear profiles in phase II. The performance of the proposed method is evaluated by average run length criterion. A comprehensive comparison is also conducted between the performance of the proposed method and the existing methods for monitoring simple linear profiles. The results show that the proposed method performs satisfactorily. In addition, the effects of reference value, sample size, and corrected sum of squares of explanatory variables on the performance of the proposed method are investigated.     

A D2D-Based Solution for MTC Connectivity Problem in NOMA-Based Cellular IoT Networks: Dynamic User Grouping and Resource Allocation

Mobile Networks and Applications - In a cellular network (CN), cellular users (CUs) located nearby machine type communications (MTC) devices (MTC-Ds) may act as uplink gateways to relay data to the...     

Scalable video traffic offloading for streaming services in 5G HetNets

Multimedia Tools and Applications - In this paper, by combining scalable video coding (SVC) and traffic offloading, we propose a scalable video traffic offloading (SVO) approach to provide video...     

Optimal data aggregation tree in wireless sensor networks based on improved river formation dynamics

The restricted energy of nodes is one of the most important challenges in wireless sensor networks. Since data transmissions among nodes consume most of the nodes' energy, thus, minimizing the unnecessary transmissions reduces the consumed energy. One of the sources of this problem is the redundancy of raw data that can be eliminated at the aggregation points. As a result, data aggregation can be considered as an effective strategy to tackle the mentioned issue and to optimize the communication energy consumption. In this paper, the sensor nodes are organized in a tree structure, and the data aggregation are done in intermediate nodes at the junction of tree branches. One of the main characteristics of tree protocols is reduction of energy consumption through optimizing the structure of a data aggregation tree. For this, this paper proposes to apply a swarm intelligent algorithm named river formation dynamics. The simulation results show that the proposed algorithm outperforms in comparison to the famous ant colony optimization algorithm in terms of network lifetime. Simulations show that the proposed algorithm makes nearly 4% and 50% improvement in lifetime of wireless sensor networks than ant colony optimization and shortest path routing, respectively.     

Effect of electrolyte concentration on microstructure and properties of micro arc oxidized hydroxyapatite/titania nanostructured composite

Micro arc oxidation was employed to grow TiO₂/hydroxyapatite composite layer on titanium substrate. The correlation between electrolyte concentration, diameter and density of the pores in fabricated layers was investigated. Therefore, the effect of electrolyte concentration on composition and morphology of grown layers was studied using SEM, EDX, XRD and XPS techniques. Samples were coated in electrolytes containing 5, 10 and 15 g/l calcium acetate and 1, 3 and 5 g/l β-glycerophosphate, at optimized voltage for 3 min. Pore size variations obey a similar pattern by the addition of both calcium acetate and β-glycerophosphatein various concentrations based on SEM observations. However, completely different volume fraction of porosities in as-obtained coatings was obtained as a result of these two components addition. Indeed, size and volume fraction of porosities in fabricated layers are directly affected by electrolyte concentration. The average crystallite size of TiO₂ and hydroxyapatite was determined as 45 nm and 48.5 nm, respectively. Moreover, the biocompatibility of selected specimens has been proved by MTT test.     

Effects of fibers and nanoparticles reinforcements on the mechanical and biological properties of hybrid composite polyetheretherketone/short carbon fiber/Nano‐SiO2

Polyetheretherketone (PEEK) composites reinforced with short carbon fibers (SCFs) (20 vol%) and nano‐SiO₂ (1, 1.5, and 2 wt%) particles were prepared by incorporating nanoparticles into PEEK/SCF composites using the internal mixer. In the development of biomaterial, both mechanical and biological characteristics must be considered. Thus, the effects of nanoparticles on the mechanical and biological properties of the PEEK/SCF composites were studied. To evaluate the mechanical properties of this biomaterial, nanoindentation method and tensile test were used. Results showed that by increasing the weight percentage of nano‐SiO₂, the elastic modulus, hardness, and tensile energies were increased. In vitro biological evaluations of the samples were done by performing cytotoxicity (3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐iphenyltetrazolium bromide assay) and cell adhesion assays. Cell–material interaction with the surface of the composite was examined by scanning electron microscopy (SEM). In all of the tests, osteoblast cells were used. Results of biological tests showed that the samples are biocompatible and they have no toxicity. Also, Adhered cells presented a normal morphology by SEM and many of the cells were observed to be undergoing cell division. POLYM. COMPOS., 34:1960–1968, 2013. © 2013 Society of Plastics Engineers     

On the dynamic detonation parameters in acetylene–oxygen mixtures with varying amount of argon dilution

In this investigation, the dynamic detonation parameters for stoichiometric acetylene–oxygen mixtures diluted with varying amount of argon are measured and analyzed. The experimental results show that the critical tube diameter and the critical energy for direct initiation of spherical detonations increase with the increase of argon dilution. The scaling behavior between the critical tube diameter d_c and the detonation cell size λ as well as the critical direct initiation energy E_c is systematically studied with the effect of argon dilution. The present results again validate that the relation d_c = 13λ holds for 0–30% argon diluted mixtures and breaks down when argon dilution increases up to 40%. It is found that the explosion length scaling of R_o ∼ 26λ becomes also invalid when the mixture contains approximately this same amount of argon dilution or more. This critical argon dilution is indeed close to that found from experiments in porous-walled tubes by Radulescu and Lee (2002) which exhibit a distinct transition in the failure mechanism. Cell size analysis in literature also indicates that the cellular detonation front starts to become more regular (or stable) when the argon dilution reaches more than 40–50%. Regardless of the degree of argon dilution or mixture sensitivity, the phenomenological model developed from the surface energy concept by Lee, which provides a relation that links the critical tube diameter and the critical energy remains valid. The present experimental results also follow qualitatively the observation from chemical kinetic and detonation instability analyses.