Coplanar Waveguide Fed Printed Antenna with Compact Size for Broadband Wireless Applications

A novel and simple coplanar waveguide fed compact antenna is introduced in this paper. The antenna structure combines the advantages of CPW with those of the broadband antenna and simplifies the structure of the antenna by reducing the number of metallization level to construct uni-planar antenna. Prototype of the proposed antenna have been constructed and studied experimentally. The measured results agrees well with the simulated prediction and shows a broad bandwidth of 6 GHz ranging from 3.5 GHz to 9.5 GHz with VSWR ≤2 (return loss ≤−10 dB), which is equivalent to 92.3% impedance bandwidth centered at 6.5 GHz. The proposed antenna shows stable radiation characteristics, gain and axial ratio of less than 1 dB over the whole operating bandwidth. Furthermore, an extensive parametric study was performed to realize the relationship between the resonance frequencies of the broadband antennas and different parameters which is helpful for advancement of the antenna design.     

Robust weighted graph transformation matching for rigid and nonrigid image registration

This paper presents an automatic point matching algorithm for establishing accurate match correspondences in two or more images. The proposed algorithm utilizes a group of feature points to explore their geometrical relationship in a graph arrangement. The algorithm starts with a set of matches (including outliers) between the two images. A set of nondirectional graphs is then generated for each feature and its K nearest matches (chosen from the initial set). Using the angular distances between edges that connect a feature point to its K nearest neighbors in the graph, the algorithm finds a graph in the second image that is similar to the first graph. In the case of a graph including outliers, the algorithm removes such outliers (one by one, according to their strength) from the graph and re-evaluates the angles until the two graphs are matched or discarded. This is a simple intuitive and robust algorithm that is inspired by a previous work. Experimental results demonstrate the superior performance of this algorithm under various conditions, such as rigid and nonrigid transformations, ambiguity due to partial occlusions or match correspondence multiplicity, scale, and larger view variation.     

All-optical 6- and 8-channel demultiplexers based on photonic crystal multilayer ring resonators in Si/C rods

In this paper, we employed multilayer ring resonators in a silicon rod base structure to realize 6-channel and 8-channel demultiplexers based on two-dimensional photonic crystals. Both the main rings and basic structures are composed of silicon rods, and the interior rings of the multilayer rings are composed of carbon. Employing silicon and carbon rods of different radii in multilayer ring resonators enhanced the coupling efficiency between the rings and waveguides. The average quality factor and power transmission efficiency were 4320 and 93%, respectively. Crosstalk values from \(-11\) to ?46 dB in conjunction with the mentioned characteristics suggest the use of the device for optical communication applications. The compact size of the proposed structure and the materials used make the proposed demultiplexer suitable for optical integrated circuits.     

Performance of Object Classification Using Zernike Moment

Moments have been used in all sorts of object classification systems based on image. There are lots of moments studied by many researchers in the area of object classification and one of the most preference moments is the Zernike moment. In this paper, the performance of object classification using the Zernike moment has been explored. The classifier based on neural networks has been used in this study. The results indicate the best performance in identifying the aggregate is at 91.4% with a ten orders of the Zernike moment. This encouraging result has shown that the Zernike moment is a suitable moment to be used as a feature of object classification systems.     

Photonic crystal-based permutation switch for optical networks

We present, for the first time, the design of a low-cross talk scalable permutation switch employing photonic crystal ring resonators in an optical network. Through this novel approach, the transition between different states of the \(2 \times 2\) optical switch, as the basic element, is achieved by applying different operating wavelengths. Subsequently, the shuffling mechanisms in \(3 \times 3\) and \(4 \times 4\) optical networks are realized by controlling the position of photonics crystal ring resonators. Lowest cross talk levels of 6 and 5% are obtained for “bar” and “cross” switching states, respectively.     

Delay constrained throughput optimisation with imperfect CSI using discrete adaptive power

Link adaptation is an effective tool to overcome fading effects in wireless links. However, time-varying adaptive transmission rate leads to queueing delay, and moreover, in practise, imperfect channel state information (CSI) is available for the transmitter to adapt its transmission rate and power. This article aims to consider practical constraints to enhance the link adaptation scheme. We reformulate and optimise buffer delay constrained throughput of a wireless link based on outdated noisy CSI. Discrete power adaptation is proposed, in which a limited number of feedback bits (just the index of transmission power level) is required, while the performance is improved compared to the constant power and is close to continuous adaptive power. A unified scheme is set-up, where constant, discrete or continuous adaptive power transmission is utilised considering average or instantaneous bit error rate constraints based on imperfect CSI. The effectiveness of our designs is evaluated by numerical evaluations.     

Theoretical Prediction of an Antimony-Silicon Monolayer $$(\hbox {penta-Sb}_{2}\hbox {Si})$$: Band Gap Engineering by Strain Effect

In this paper, using a first principles calculation, a two-dimensional structure of silicon-antimony named penta-Sb\(_{2}\)Si is predicted. The structural, kinetic, and thermal stabilities of the predicted monolayer are confirmed by the cohesive energy calculation, phonon dispersion analysis, and first principles molecular dynamic simulation, respectively. The electronic properties investigation shows that the pentagonal Sb\(_{2}\)Si monolayer is a semiconductor with an indirect band gap of about 1.53 eV (2.1 eV) from GGA-PBE (PBE0 hybrid functional) calculations which can be effectively engineered by employing external biaxial compressive and tensile strain. Furthermore, the optical characteristics calculation indicates that the predicted monolayer has considerable optical absorption and reflectivity in the ultraviolet region. The results suggest that a Sb\(_{2}\)Si monolayer has very good potential applications in new nano-optoelectronic devices.     

Radio-over-free space optical space division multiplexing system using 3-core photonic crystal fiber mode group multiplexers

Wireless Networks - Radio over free space optics (Ro-FSO) systems have previously relied on the signal intensity, wavelength and polarization for multiplexing data streams in...     

Energy Detector in Ultra Wideband Systems Using Phase Compensation Technique

Energy detectors have the advantage of simple structure and inexpensive price. Due to the low signal to noise ratio (SNR) of the received signal in ultra-wideBand (UWB) system, these desirable advantages can be achieved at the expense of non-trivial performance degradation. This paper presents a phase compensation (PC) technique to improve the performance of energy detector in UWB systems. In PC-UWB, the frequency dependent phase of the system response at the transmitter is extracted and its opposite spectral phase is used as prefilter. Because of Low complexity, cost and energy consumption of energy detectors, PC techniques has extensive potential for future of UWB communication systems. Measurement results show that the use of PC-UWB leads to signal power concentration at the receiver, which reduces the number of RAKE fingers required in coherent detection as well as achieves a higher data rate with less intersymbol interference. However time reversal UWB can achieve secure data transmission, but its performance is worse than PC-UWB. Simulation results show that phase compensation reduces the inter symbol interference impacts. Therefore it is possible to use a simple receiver with insignificant performance degradation. It is also shown that PC-UWB considerably outperforms TR-UWB and has satisfying performance in SNR greater than 13 dB.