Many self-adaptation routing schemes have been proposed for sensor networks. The most relevant of them consider a hierarchical topology and aim to meet energy conservation and QoS requirements in a homogeneous environment. In such networks, one specific algorithm is commonly applied by all nodes inside clusters. Contrarily, in this paper, we propose a heterogeneous routing by applying different strategies according to specific parameters at the same time inside different clusters. Moreover, each cluster can adopt different strategies at different moments under different conditions. This approach leads to a new self-adaptation protocol based on heterogeneity of the routing process in a multi-hop clustering WSN. The proposal uses a set of mechanisms that have been adopted in well-known protocols (HEEP, APTEEN, LEACH, PEGASIS, etc.) taking into account their strengths and weaknesses. Simulations under NS2 show that our proposal, based on heterogeneous routing protocol, prolongs the network lifetime with different ratios compared to HEEP, PEGASIS and others.

Tin oxide SnO2 thin films were deposited by sol gel method on glass substrates. The as-deposited thin films were then annealed at 550 °C for different time durations (15, 30, 60 and 120 min). Structural and morphological investigations were carried out on all samples by X-ray diffraction method and atomic force microscopy while optical properties were obtained with UV–Visible spectrophotometer. XRD patterns reveals that the samples possess polycrystalline with rutile structure of SnO2 without any secondary phase. AFM image showed that SnO2 thin films having a smooth surface morphology. The optical properties in the visible range showed that the deposited layers have a high transmission factor. The optical band gap energy varies in the range of 3.61–3.73 eV. Finally, ultraviolet (UV) detection properties of samples as an active layer in UV photodetector devices were investigated. Current-voltage characteristics of the SnO2 thin films are performed under dark and light environment, which show low dark current of 22.9 nA with a linear behavior and high current ration > 104 under 2 V applied voltage and 120 min as annealing time. Whereas, high photocurrent is observed for samples annealing for 30 min. Moreover, the transient photoresponse of the fabricated device is reported under different annealing times.

The present paper concerns a computational study of a three-dimensional (3D) unit cells with identical spherical voids in a von Mises matrix. The objective is to estimate the effective plastic flow surface of 3D microstructures. The work originality is to deal with identical spherical overlapping voids, covering a wide range of stress triaxiality ratios. The effective plastic flow surface is computed for nine distinct loadings on four distinct microstructures. The result indicates that the classical Gurson–Tvergaard–Needleman (GTN) model obtained using the Fritzen et al.parameters, matches with our numerical simulations.

In this paper, a new particle swarm optimization-based approach is proposed for the geometrical optimization of the nanowires solar cells to achieve improved optical performance. The proposed hybrid approach combines the 3-D numerical analysis using accurate solutions of Maxwell’s equations and metaheuristic investigation to boost the solar cell total absorbance efficiency. Our purpose resides on modulating the electric field and increasing the light trapping capability by optimizing the radial solar cell geometrical parameters. Moreover, a comprehensive study of vertical core-shell nanowire arrays optical parameters such as the integral absorption, reflection, and total absorbance efficiency is carried out, in order to reveal the optimized radial solar cells optical performance for low-cost photovoltaic applications. We find that the proposed hybrid approach plays a crucial role in improving the nanowires solar cells optical performance, where the optimized design exhibits superior total absorbance efficiency and lower total reflection in comparison with those provided by the conventional planar design. The obtained results make the proposed global optimization approach valuable for providing high-efficiency nanowires solar cells.

In this paper, a new particle swarm optimization-based approach is proposed for the geometrical optimization of the nanowires solar cells to achieve improved optical performance. The proposed hybrid approach combines the 3-D numerical analysis using accurate solutions of Maxwell’s equations and metaheuristic investigation to boost the solar cell total absorbance efficiency. Our purpose resides on modulating the electric field and increasing the light trapping capability by optimizing the radial solar cell geometrical parameters. Moreover, a comprehensive study of vertical core-shell nanowire arrays optical parameters such as the integral absorption, reflection, and total absorbance efficiency is carried out, in order to reveal the optimized radial solar cells optical performance for low-cost photovoltaic applications. We find that the proposed hybrid approach plays a crucial role in improving the nanowires solar cells optical performance, where the optimized design exhibits superior total absorbance efficiency and lower total reflection in comparison with those provided by the conventional planar design. The obtained results make the proposed global optimization approach valuable for providing high-efficiency nanowires solar cells.

In this paper, a new design methodology by optimizing the silicon/organic interface morphology is proposed to achieve superior optical behavior for pentacene-based organic/inorganic solar cells. Our purpose dwells on reducing the refracting light in the silicon and improves the absorbance behavior in the solar cell. In this context, a numerical model based on accurate solutions of Maxwell’s equations is developed in order to study the impact of both interface texturization morphologies (triangular and grooves) on the optical absorbance and electrical performance. It is found that the proposed design morphology has profound implication on modulating the electric field, which increases the light trapping capability. It is also confirmed that the overall electrical performance is significantly improved as compared to the conventional organic/inorganic solar cells, where the proposed design exhibits superior integral absorption behavior and large interface area. Moreover, a new hybrid approach by combining of the numerical and metaheuristic models is developed to boost the device performance by optimizing the interface morphology. The obtained results make the proposed design methodology valuable for providing high-efficiency organic/inorganic solar cells.

In this paper, an electromagnetic approach based on cavity model in conjunction with electromagnetic knowledge was developed. The cavity model combined with London’s equations and the Gorter-Casimir two-fluid model has been improved to investigate the resonant characteristics of high Tc superconducting circular microstrip patch in the case where the patch is printed on uniaxially anisotropic substrate materials.  Merits of our extended model include low computational cost and mathematical simplify. The numerical simulation of this modeling shows excellent agreement with experimental results available in the literature. Finally, numerical results for the dielectric anisotropic substrates effects on the operating frequencies for the case of superconducting circular patch are also presented.

An efficient small size electromagnetic energy harvesting sensor for low-DC-power applications is proposed. The sensor consists of two main parts: a dual polarisation square patch antenna used to collect the RF energy at a central frequency of 2.45 GHz, and two voltage doublers rectifier circuit for the RF-to-DC conversion. The overall size of the design is 50 × 50 × 6.2 mm 3 . Firstly, the antenna is designed using high-frequency structure simulator software; followed by the design of the rectifier circuit in advanced design system. After simulations, a sensor prototype is fabricated using F4B as the antenna substrate. Measurements show that the sensor achieves a comparatively high maximum measured efficiency of 41% for a power level of -10 dBm. The sensor has a simple structure, it is compact sized, light weight, and presents a high RF-to-DC conversion efficiency for low-RF-power levels which can be used to charge different low-DC-power devices.

In this paper, an efficient full-wave analysis of a circular microstrip patch printed on suspended and composite substrates is performed using a dyadic Green’s function formulation. Galerkin’s technique is used in the resolution of the integral equation of the electric field. The TM set of modes issued, from the magnetic wall cavity model, are used to expand the unknown currents on the circular patch. The radiation patterns are expressed regarding the transforms of the currents. The convergence of the method is proven by calculating the resonant frequencies, half-power bandwidths, and quality factors for several configurations. The computed results are found to be in excellent agreement with those observed in the literature. The numerical results obtained show that the bandwidth increases with the increase in the thickness of the suspended or composite substrates, especially for low permittivity of the second layer. Also, it is demonstrated that the resonant frequencies of the circular microstrip patch on suspended and composite substrates can be adjusted to obtain the maximum operating frequency of the antenna. Finally, the effect of the presence of the second layer under the circular patch on the radiation patterns is also investigated.