Joint range assignment and routing to conserve energy in wireless ad hoc networks

In wireless ad hoc networks, energy utilization is perhaps the most important issue, since it corresponds directly to the operational network lifetime. Topology Control (TC) is a well-known energy saving technique which tries to assign transmission ranges of nodes to optimize their energy utilization while keeping the network connected. In current TC schemes, the transmission range of each node is mostly accounted as the exclusive estimator for its energy consumption, while ignoring the amount of data it forwards. Especially when such schemes are coupled with the popular shortest path routing, they usually create a highly-loaded area at the center of the network in which nodes deplete their battery very quickly. In this paper, we introduce efficient strategies that take both load and range into account to handle this problem. We first consider the simple strategy in which a proper transmission range is computed for all nodes of the network to optimize their energy utilization under the presence of the shortest path routing. Inspiring from the results of this strategy, we then propose our combined strategy and argue that a combination of circular paths and shortest paths could result in a much better solution. We also provide detailed analytical models to measure the forwarding load and interference of nodes and then corroborate them with simulation results. Using the combined strategy, the achieved improvement in terms of traffic load, interference, and maximum energy consumption is about 50%, as compared with the simple strategy.     

Nonlinear fractional‐order power system stabilizer for multi‐machine power systems based on sliding mode technique

This paper presents two novel nonlinear fractional‐order sliding mode controllers for power angle response improvement of multi‐machine power systems. First, a nonlinear block control is used to handle nonlinearities of the interconnected power system. In the second step, a decentralized fractional‐order sliding mode controller with a nonlinear sliding manifold is designed. Practical stability is achieved under the assumption that the upper bound of the fractional derivative of perturbations and interactions are known. However, when an unknown transient perturbation occurs in the system, it makes the evaluation of perturbation and interconnection upper bound troublesome. In the next step, an adaptive‐fuzzy approximator is applied to fix the mentioned problem. The fuzzy approximator uses adjacent generators relative speed as own inputs, which is known as semi‐decentralized control strategy. For both cases, the stability of the closed‐loop system is analyzed by the fractional‐order stability theorems. Simulation results for a three‐machine power system with two types of faults are illustrated to show the performance of the proposed robust controllers versus the conventional sliding mode. Additionally, the fractional parameter effects on the system transient response and the excitation voltage amplitude and chattering are demonstrated in the absence of the fuzzy approximator. Finally, the suggested controller is combined with a simple voltage regulator in order to keep the system synchronism and restrain the terminal voltage variations at the same time. Copyright © 2014 John Wiley & Sons, Ltd.     

Significance of Capping Agents of Colloidal Nanoparticles from the Perspective of Drug and Gene Delivery,Bioimaging, and Biosensing: An Insight

The over-growth and coagulation of nanoparticles is prevented using capping agents by the production of stearic effect that plays a pivotal role in stabilizing the interface. This strategy of coating the nanoparticles’ surface with capping agents is an emerging trend in assembling multipurpose nanoparticles that is beneficial for improving their physicochemical and biological behavior. The enhancement of reactivity and negligible toxicity is the outcome. In this review article, an attempt has been made to introduce the significance of different capping agents in the preparation of nanoparticles. Most importantly, we have highlighted the recent progress, existing roadblocks, and upcoming opportunities of using surface modified nanoparticles in nanomedicine from the drug and gene delivery, bioimaging, and biosensing perspectives.     

Large magnetocaloric effect and magnetoresistance in ErNi single crystal

The magnetic properties,magnetocaloric effect and magnetoresistance in ErNi single crystal have been investigated in detail.With decreasing temperature,ErNi single crystal undergoes two successive mag-netic transitions:a paramagnetic to ferromagnetic transition at Tc=11 K and a spin-reorientation transition at TSR=5 K.Meanwhile,a sharp field-induced metamagnetic transition is observed below the Tc along the a axis.ErNi single crystal possesses a giant magnetocaloric effect around Tc.The maximum magnetic entropy change is-36.1 J(kg K)-1 along the a axis under the field change of 0-50 kOe.In par-ticular,the rotating magnetocaloric effect in ErNi single crystal reaches its maximum under a relatively low field,and the maximum rotating entropy change with a value of 9.3 J(kg K)-1 is obtained by rotat-ing the applied field from the[011]to[100]directions under 13 kOe.These results suggest that ErNi could be a promising candidate for magnetic refrigeration working at liquid-helium temperature region.Moreover,a complicated transport behavior is uncovered in ErNi single crystal,which is attributed to the complex magnetic states and magnetic polaronic effect.Both positive and negative magnetoresistance are observed.A considerable large magnetoresistance with the value of-34.5％is acquired at 8 K under 50 kOe when the field is along the[100]direction.     

Highly sensitive voltammetric and impedimetric sensor based on an ionic liquid/cobalt hexacyanoferrate nanoparticle modified multi-walled carbon nanotubes electrode for diclofenac analysis

This paper describes the development of 1-methyl-3-butylimidazolium chloride ionic liquid/cobalt hexacyanoferrate nanoparticle modified multi-walled carbon nanotubes nanocomposite paste electrode for the electrocatalytic and adsorptive stripping voltammetric and impedimetric determination of diclofenac (DIC) in real samples. The nanocomposite was prepared by a simple chemical method and was characterised by scanning electron microscopy, Fourier transform infrared spectroscopy and atomic absorption spectroscopy. Also, the electrochemical behaviours of the modified electrode and the electrocatalytic oxidation of DIC were investigated in detail by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy techniques. The kinetic parameters such as electron transfer coefficient, and apparent rate constant for the redox reaction between DIC and the modified electrode were also determined using electrochemical approaches. It was found that the modified electrode exhibited excellent electrocatalytic activity toward the oxidation of DIC, and under the optimised conditions, the linear response range and detection limit were found to be 1.0–100.0 and 0.3 μM, respectively using the differential pulse voltammetry method. The proposed method was applied for the sensitive and selective determination of diclofenac in the urine samples and pharmaceutical formulations with satisfactory results.     

Engineered catalyst layer design with graphene-carbon black hybrid supports for enhanced platinum utilization in PEM fuel cell

In this study, a new approach was applied to prepare platinum/reduced graphene oxide/carbon black (Pt/rGO/CB) hybrid electrocatalysts. Unlike literature firstly GO and CB in varying ratios are homogeneously mixed with a high shear mixer and then Pt was impregnated onto the hybrid support structure according to the polyol method. According to our approach CB was used as a spacer and intercalating agent in both Pt impregnation and electrode preparation to avoid restacking and increase the Pt utilization. Thus rGO/CB based hybrid support can ease the diffusion while it is promoting to the use of high electrical connectivity and surface area of graphene. The maximum power density of 645 mW cm^?2 with Pt utilization efficiency of 2.58 kW/gPt was achieved with the hybrid containing the smallest amount of CB. It seems that this small amount of CB effectively modifies the electrode structure. The enhanced fuel cell performance can be attributed to synergistic effects from graphene and CB providing better mass transport and Pt utilization in the catalyst layer.     

Wavelet-Aided Analysis to Estimate Seasonal Variability and Dominant Periodicities in Temperature,Precipitation, and Streamflow in the Midwestern United States

The study explores the conjunction of Discrete Wavelet Transform along with trend and shift detection techniques to analyze variability in seasonal temperature, precipitation, and streamflow across the Midwestern United States. The analysis was performed using three dyadic scales that corresponded to periodicities of two, four, and eight years, referred to as D1, D2, and D3, respectively. The study utilized Mann-Kendall test to analyze trends having variations accounting for serial correlation. Pettit’s test was used to detect shift changes in the hydrologic variables. The results of shift changes also were tested for coincidence with El Niño Southern Oscillation (ENSO) in relation to Pacific Decadal Oscillation (PDO). The temperature and precipitation over 106 climate divisions as well as streamflow over 88 stations were evaluated over the period of 1960–2013. Results indicated an increasing temperature trend, with D2 and D3 being the most effective periodic components in detecting trends in winter, spring, and summer; D1 and D3 were most effective in detecting trends in temperature in fall. Likewise, precipitation and streamflow showed dominance of the D3 component in detecting trends. More shifts than trends were detected in all the hydrologic variables indicating abrupt changes in climate in the region. Temporally, shifts were observed from 1975 to 1995, and spatially shift years varied across the Midwest. Most shift changes coincided with PDO and ENSO phases. The results will aid water managers to better prepare for the future emphasizing the need to make planning and operation more flexible to improve the efficiency of water use.     

A review on automated diagnosis of malaria parasite in microscopic blood smears images

Multimedia Tools and Applications - Malaria is a life-threatening disease caused by parasite of genus plasmodium, which is transmitted through the bite of infected Anopheles. A rapid and accurate...     

Analysis of Strain Rate Sensitivity of Ultrafine-Grained AA1050 by Stress Relaxation Test

Commercially pure aluminum sheets, AA 1050, are processed by accumulative roll bonding (ARB) up to eight cycles to achieve ultrafine-grained (UFG) aluminum as primary material for mechanical testing. Optical microscopy and electron backscattering diffraction analysis are used for microstructural analysis of the processed sheets. Strain rate sensitivity (m-value) of the specimens is measured over a wide range of strain rates by stress relaxation test under plane strain compression. It is shown that the flow stress activation volume is reduced by decrease of the grain size. This reduction which follows a linear relation for UFG specimens, is thought to enhance the required effective (or thermal) component of flow stress. This results in increase of the m-value with the number of ARB cycles. Strain rate sensitivity is also obtained as a monotonic function of strain rate. The results show that this parameter increases monotonically by decrease of the strain rate, in particular for specimens processed by more ARB cycles. This increase is mainly linked to enhanced grain boundary sliding as a competing mechanism of deformation acting besides the common dislocation glide at low strain rate deformation of UFGed aluminum. Recovery of the internal (athermal) component of flow stress during the relaxation of these specimens seems also to cause further increase of the m-value by decrease of the strain rate.