No abstract

No abstract

No abstract

The simulation-driven metaheuristic algorithms have been successful in solving numerous problems compared to their deterministic counterparts. Despite this advantage, the stochastic nature of such algorithms resulted in a spectrum of solutions by a certain number of trials that may lead to the uncertainty of quality solutions. Therefore, it is of utmost importance to use a correct tool for measuring the performance of the diverse set of metaheuristic algorithms to derive an appropriate judgment on the superiority of the algorithms and also to validate the claims raised by researchers for their specific objectives. The performance of a randomized metaheuristic algorithm can be divided into efficiency and effectiveness measures. The efficiency relates to the algorithm's speed of finding accurate solutions, convergence, and computation. On the other hand, effectiveness relates to the algorithm's capability of finding quality solutions. Both scopes are crucial for continuous and discrete problems either in single-or multi-objectives. Each problem type has different formulation and methods of measurement within the scope of efficiency and effectiveness performance. One of the most decisive verdicts for the effectiveness measure is the statistical analysis that depends on the data distribution and appropriate tool for correct judgments.

A review paper concerning wide-band and ultra-wideband (UWB) antennas used for wireless communication purposes in terms of the materials as well as a numerical analysis is presented. These antennas which are taken into account are listed as wide-band microstrip antenna, wide-band monopole antenna over a plate, wide-slot UWB antenna, stacked patch UWB antenna, taper slot (TSA) UWB antenna, metamaterial (MTM) structure UWB antennas, elliptical printed monopole UWB antenna, and flexible wearable UWB antenna. The antennas’ performance is compared based on their size and how they can be applicable for portable communication device applications. This review paper furnishes a proper direction to select varieties of figures in terms of impedance bandwidth, gain, directivity, dimensions, time domain characteristics, and materials affecting these antenna’s characteristics.

This article presents the design of a droplet shape ultra-wide band antenna for imaging of wood. The proposed antenna is designed on PTFE substrate with a dielectric constant of 2.55, loss tangent of 0.001- and 2.4-mm thickness. The antenna is loaded by a stub to resonate at lower band frequency, strip loading at the back, and a chamfered ground to increase the bandwidth. Despite having miniaturized dimensions of 15 mm × 15 mm, it shows better results compared to recent studies. The simulation results depict a good ultra-wide bandwidth from 3.26 GHz to 20 GHz, and 21.5–25 GHz; Besides, the proposed antenna has two bands at 1.25–1.35 GHz and 1.7–1.81 GHz. In addition to that, the antenna achieved a maximum gain of 5.69 dB and directivity of 7.3 dBi. The measurement results of S-parameters transmitted and received signals performed in air, plywood, and high-density wood show a good agreement with the simulated results. In addition, the measured results illustrate a good isolation and uniform illumination among arrays as well as the received signals’ shapes do not change in different environments, but only the amplitude. Hence, the proposed antenna seems to be adequate for microwave imaging of wood.

No abstract

No abstract