Optimization of I-shape Microstrip patch antenna using PSO and curve fitting

This paper presents an optimization of Microstrip patch antenna, based on Particle Swarm Optimization (PSO) with curve fitting. An I shape antenna is used to demonstrate the optimization technique. An initial antenna is designed by cutting slots in rectangular patch to form shape I. By varying different parameters of the antenna, the data for developing PSO program in MATLAB is obtained. For Simulation, software IE3D and Graphmatica is used for Curve Fitting. Thus the optimized antenna is obtained, and finally the performance of the initial antenna is compared with the PSO optimized antenna. The result yields that obtained antenna have resonance near at 2.4 GHz and it also shows remarkable improvement over Fractional Bandwidth. For the Microstrip line feed I shape antenna, the Fractional Bandwidth is increased by 25 % as compared to the initial antenna.     

A way to measure power-quality indices in devices for monitoring processes that take place in overhead power-transmission lines

A generalized structure of an algorithm for measuring the power-quality indices is examined. The specific features of the algorithm’s blocks and possible ways to interpret it for different purposes and soft- and hardware abilities are shown. Ways to test the algorithm at every stage of development (from verification of the mathematical model to software debugging) are described. We analyze the algorithm’s operation in the LabView environment for measuring power-quality indices. A multifunctional device for measuring power quality in accordance with GOST (State Standard) 30804.4.30-2013 is presented. Bench tests of the multi-functional device under different operating conditions and when carrying out different functions in the frame of one soft- and hardware platform are carried out.     

An accurate computation method based on artificial neural networks with different learning algorithms for resonant frequency of annular ring microstrip antennas

An annular ring compact microstrip antenna (ARCMA) constructed by loading a circular slot in the center of the circular patch antenna is a popular microstrip antenna due to its favorable properties. In this study, a method based artificial neural networks (ANNs) has been firstly applied for the computing the resonant frequency of ARCMAs. Multilayered perceptron model based on feed forward back propagation ANN has been utilized, and the constructed model have been separately trained with 8 different learning algorithms to achieve the best results regarding the resonant frequency of ARCMAs at dominant mode. To this end, the resonant frequencies of 80 ARCMAs with varied dimensions and electrical parameters in accordance with UHF band covering GSM, LTE, WLAN and WiMAX applications were simulated with a robust numerical electromagnetic computational tool, \(\hbox {IE3D}^\mathrm{TM}\) , which is based on method of moment. Then, ANN model was constructed with the simulation data, by using 70 ARCMAs for training and the remaining 10 for test. As the performances of the 8 learning algorithms are compared with each other, the best result is obtained with Levenberg–Marquardt algorithm. The proposed ANN model were confirmed by comparing with the suggestions reported elsewhere via measurement data published earlier in the literature, and they have further validated on an ARCMA fabricated in this study. The results achieved in this study show that ANN model learning with LM algorithm can be successfully used to compute the resonant frequency of ARCMAs without involving any sophisticated methods.     

Quantum drift-diffusion model for IMPATT devices

Quantum correction is necessary on the classical drift-diffusion (CLDD) model to predict the accurate behavior of high frequency performance of ATT devices at frequencies greater than 200 GHz when the active layer of the device shrinks in the range of 150–350 nm. In the present work, a quantum drift-diffusion model for impact avalanche transit time (IMPATT) devices has been developed by incorporating appropriate quantum mechanical corrections based on density-gradient theory which macroscopically takes into account important quantum mechanical effects such as quantum confinement, quantum tunneling, etc. into the CLDD model. Quantum potentials (synonymous as Bohm potentials) have been incorporated in the current density equations as necessary quantum mechanical corrections for the analysis of millimeter-wave (mm-wave) and Terahertz (THz) IMPATT devices. It is observed that the large-signal (L-S) performance of the device is degraded due to the incorporation of quantum corrections into the model when the frequency of operation increases above 200 GHz; while the effect of quantum corrections are negligible for the devices operating at lower mm-wave frequencies.     

Gain enhancement and broadband RCS reduction of a circularly polarized aperture-coupled annular-slot antenna using metasurface

A circularly polarized microstrip slot antenna with low radar cross-section (RCS) and high gain was designed using a metasurface composed of a \(6 \times 6\) array of corner-truncated square patches placed on top of the upper substrate. By optimizing the geometry of the metasurface patches and L-shaped feed of the proposed antenna, broadband RCS reduction and improved overall antenna performance were achieved. A prototype antenna was fabricated, and the results showed that the proposed antenna exhibited an impedance bandwidth of 29.08 % in the frequency band of 4.29–5.75 GHz. The designed antenna achieved good 3-dB axial ratio (AR) bandwidth of about 30.18 % with center frequency of 5.3 GHz, and gain in the broadside direction of 9.9 dBi. Using the designed metasurface, remarkable monostatic RCS reduction was obtained in the frequency range from 4 to 13 GHz.     

Impact of Auger recombination parameterisations on predicting silicon wafer solar cell performance

For high-efficiency silicon wafer solar cells, Auger recombination is becoming one of the most important efficiency limiting factors. For this purpose it is desirable to be able to use different Auger recombination parameterisations in advanced computer simulations. In this paper we present a method to implement arbitrary Auger parameterisations in the software package Sentaurus TCAD, enabling two- and three-dimensional simulation of solar cells using different Auger parameterisations. As examples, we implemented and investigated three different Auger parameterisations (proposed by Altermatt et al., by Kerr and Cuevas, and by Richter et al.) from the literature. For verification, we simulate Auger lifetimes for different doping densities and injection levels in crystalline silicon. The simulated Auger lifetimes are found to agree well with analytical solutions (differences less than 0.001 %). We then employ the three different Auger parameterisations for fitting measured effective lifetime curves of both \(n\) -type and \(p\) -type float-zone silicon lifetime samples and show which models are applicable under which conditions. We further compare the difference between the three Auger parameterisations by simulating characteristics of a screen-printed aluminium local back surface field silicon wafer solar cell. The simulation results agree well with the characterisation results. We find that the choice of Auger parameterisation can lead to significant differences in the predicted solar cell behaviour under one-Sun illumination. We demonstrate that different Auger parameterisations may result in significant differences in the blue response, by simulating a heavily doped emitter of an aluminium local back surface field silicon wafer solar cell.     

A compact modelling of double-walled gate wrap around carbon nanotube array field effect transistors

The effects of multi-walled CNTs and array of channels are combined to form Double-walled Gate Wrap Around Carbon Nano Tube array Field Effect Transistor (DWGWA CNTFET). Numerical model is proposed for the device to study its performance. Screening and imaging effects of adjacent and inter walls in array of channels are included for calculating the drive capacitance, subsequently the drive current. This model suits for a wide range of chiralities and diameters. The change in drive capacitance of double-walled and single-walled device with respect to various drain and gate voltage for different values of number of channels, diameters are studied. The number of channels, CNTs diameters, chiralities of the tubes, source/drain length are varied and the corresponding responses of drive current, cut off frequency, signal delay time for both double and single walled devices are compared. In all cases, DWGWA CNTFET excels in its performance over Single-walled Gate Wrap Around Carbon Nano Tube array Field Effect Transistor (SWGWA CNTFET).The model of the proposed device can be utilized for designing the Nano devices with high power and high speed capability.     

Role of inelastic electron–phonon scattering in electron transport through ultra-scaled amorphous phase change material nanostructures

The electron transport through ultra-scaled amorphous phase change material (PCM) GeTe is investigated by using ab initio molecular dynamics, density functional theory, and non-equilibrium Green’s function, and the inelastic electron–phonon scattering is accounted for by using the Born approximation. It is shown that, in ultra-scaled PCM device with 6 nm channel length, \(<\) 4 % of the energy carried by the incident electrons from the source is transferred to the atomic lattice before reaching the drain, indicating that the electron transport is largely elastic. Our simulation results show that the inelastic electron–phonon scattering, which plays an important role to excite trapped electrons in bulk PCM devices, exerts very limited influence on the current density value and the shape of current–voltage curve of ultra-scaled PCM devices. The analysis reveals that the Poole–Frenkel law and the Ohm’s law, which are the governing physical mechanisms of the bulk PCM devices, cease to be valid in the ultra-scaled PCM devices.     

Two-dimensional accelerated MP-RAGE imaging with flexible linear reordering

Object

Implementation of an accelerated Magnetization Prepared RApid Gradient Echo (MP-RAGE) sequence for T1 weighted neuroimaging; exploiting modern MRI technologies to minimize scan time while preserving the image quality.

Materials and methods

A custom MP-RAGE sequence was implemented on a state-of-the-art 3T MR scanner equipped with a 32-channel receiver array head coil. The sequence utilized a shifted CAIPIRINHA k _y –k _z under-sampling pattern combined with elliptical scanning and a two-dimensional view ordering scheme to achieve high parallel imaging acceleration factors at maintained image contrast.

Results

It could be shown that MP-RAGE accelerated in two k-space directions outperforms single direction acceleration, which is the common practice with standard view ordering. Applying the CAIPIRINHA technique in conjunction with elliptical scanning further increased this benefit.

Conclusion

By combining MP-RAGE with CAIPIRINHA sampling and elliptical scanning, the scan time can be reduced from 4–5 min to 2–3 min with insignificant reduction in image quality.     

Small-size scarecrow-shaped CPW and microstrip-line-fed UWB antennas

In this paper, a scarecrow-shaped ultrawideband (UWB) antenna is presented using CPW and microstrip line feeding. The physical dimensions of the proposed antennas are \(25 \times 20 \times 1.6\,\hbox { mm}^{3}\), in which the modification in the ground is made by etching two half-circle and square slots symmetrical with respect to center feed line. The measured impedance bandwidth (return loss \(<\,10\,\hbox {dB}\)) obtained for CPW-fed antenna is 147.13% (2.51–16.48 GHz), and for microstrip-line-fed antenna it is 139.88% (2.86–16.17 GHz). Various antenna parameters for both the designs are calculated, such as gain, radiation pattern and group delay which are quite acceptable for UWB applications. The proposed designs are first simulated by the CST Microwave Studio, and optimized designs are fabricated. The simulated and measured results are compared for the validation of the design.     

面向射频能量收集的小型化超材料整流天线设计

为了高效收集空间存在的射频能量,提出了一种新型的射频能量收集系统：首先,设计了一种单极子微带天线,其性能稳定且易于加工;其次,结合超材料理论设计了一种基于开口环形谐振器的超材料单元,其内环采用曲流技术,从而使天线小型化;最后通过将超材料单元加载在微带天线上对其进行了改进,能够进一步减小天线尺寸,改善带宽、增益等性能。系统由小型化超材料天线、匹配电路、整流电路及负载组成,对天线及整流电路进行仿真优化。经过实际加工测试,系统在2.45 GHz时输出电压为318 mV,对应的最大整流效率为13.5%。     

Electronic transport across a layered structure of Fe/\upbeta -poly vinylidene fluoride/Fe using DFT calculations

Quantum electronic transport across a \(\upbeta \) -poly(vinylidene fluoride) ( \(\upbeta \) -PVDF) ferroelectric barrier structured between two ferromagnetic Fe layers is explored using DFT calculations. The multifunctional junction is organized in capacitor like structure, as FM (ferromagnetic metal)/FE (ferroelectric)/FM to understand the mechanism of electron transfer by controlling the spin polarization of the electrodes and also the ferroelectric polarization of the barrier. These studies are carried on a single bcc layer of Fe atoms in both the electrodes and two monomers of PVDF is utilized as a barrier. We investigated the dependence of total density of states (DOS), projected DOS, transmission coefficient and I–V characteristics on applied bias voltage using SIESTA & TRANSIESTA package.     

A novel quantum-dot cellular automata CLB of FPGA

Quantum-dot cellular automata (QCA) is a promising, emerging nano-technology based on single electron effects in quantum dots and molecules. This paper presents design, implementation and simulation of a configurable logic block for a field programmable gate arrays (FPGA) by QCA. Previous works focus on QCA-based FPGA that have fixed logic and programmable interconnection or programmable logic and fixed interconnection; however, proposed structures in this paper have programmable logic and programmable interconnection. The presented look-up table implemented with novel structure which has been allowed as frequently as the read/write operation occurs, also acts as a pipeline. In this paper, we presented novel decoders and multiplexers and implemented with QCA, designed with the minimum number of majority gates and cells. Finally, a new configurable logic block (CLB) is designed, implemented and simulated in the QCA, which used signal distribution network method to avoid the coplanar problem of crossing wires. Also, QCADesigner software is used for detailed layout and QCADesigner attend with HDLQ verilog are used for circuit simulation. The proposed CLB is simulated with programming by the QCADesigner software. The area and delay of QCA-based CLB presented in this paper compared to the CLB based on CMOS, nanomaterial and CNT (32 nm). Results show that proposed CLB will do the task with a minimum clock and can be configured as a FPGA.     

On the performance of microstrip antenna embedded in composite laminated substrates

Fiber‐reinforced composite structures can be tailored to desire mechanical properties and to embed microstrip antenna in aerospace applications. The electromagnetic characteristics of a microstrip antenna on isotropic and uniaxial substrates have been known, but that embedded in composite laminated substrates remain unavailable to date. This work aims at analyzing the performance of microstrip antenna embedded in composite laminated substrates by spectral domain analysis. Parameter studies are conducted to investigate the effects of the substrate's dielectric constants, the fiber directions (the orientation between the antenna and the laminate layers), and the stacking sequence on antenna's resonant frequency and radiation pattern. The antenna size when embedded in composite laminated substrates is larger than that when attached on isotropic substrates, or conversely, the resonant frequency will deviate lower if assuming the substrate as isotropic. The far‐field pattern in composite laminated substrates is more ‘directional’ than that in isotropic substrates. The antenna gain in the substrates of symmetric stacking with ±45° fiber direction is 20 dB better than that in isotropic substrates in some elevations. Copyright © 2014 John Wiley & Sons, Ltd.     

Slot loaded rectangular patch antenna for dual-band operations on glass-reinforced epoxy laminated inexpensive substrate

This paper presents a straightforward design and analysis of rectangular radiating patch with narrow slots and microstrip line fed patch antenna for dual band operations. A parametric analysis has been carried on during the design process for finding the desired resonant frequencies. The final design concept of the antenna has been validated through fabricating the antenna prototype and then measuring its characteristics. The proposed antenna is implemented by using cost effective FR4 substrate, which comprises of vertical narrow slots on the radiating element and partial ground plane. The experimental results of the antenna prototype show the impedance bandwidth ( \(<-10\) dB reflection coefficient, S11) 396.4 MHz (286.9–683.3 MHz) and 310 MHz (4.28–4.59 GHz) with center resonant frequency 460 MHz and 4.5 GHz respectively. The proposed antenna has achieved 6.6 dBi average gain with 85 % average radiation efficiency for lower band and 9.7 dBi average gain with 88 % radiation efficiency for upper band. The bandwidths of the antenna are broader enough to cover medical telemetry communications, UHF wireless communications and terrestrial communications services.     

A new approach to analyze a resistive patch antenna excited by a microstrip line and printed on an anisotropic substrate with superstrate

An improved model is presented to study the effect of a superstrate on a resistive rectangular microstrip antenna fed by a microstrip line and printed on anisotropic substrate. A new accurate computation with different unknown currents of the electric field on overlap, feed line and resistive patch is studied by the Fourier transform, considering the Galerkin’s method and entire domain basis functions. Additionally, the scattering radar cross section (RCS) was studied for this novel resistive patch taking into account the effect of the nonzero surface resistance, the superstrate and the anisotropic substrate. To determine the unknown current modes on the patch, the electric field integral equation can be discretized into a matrix form that incorporates the effect of the superstrate, the anisotropic substrate and the currents on the feed line which are efficiently developed. Moreover, the necessary terms to represent the resistive patch are derived and are included in the equation in the form of a resistance matrix. RCS reduction is obtained for high superstrate thicknesses and low superstrate permittivities. Also, the addition of a resistance on the surface of the patch antenna provides a scattered energy diminution. Moreover, the RCS of this novel structure is affected by both \(\varepsilon _z \) and \(\varepsilon _x \) permittivities change, however, has drastically changed due to the \(\varepsilon _x \) permittivity change. In order to validate the theoretical results, a study has been achieved for a perfectly conducting patch on isotropic substrate, without superstrate and excitation, and the results were compared well with other papers. This subject has not been treated or reported previously in the literature, and there has been very little work on the scattering RCS of only simple perfectly conducting patch antennas.     

Accelerated redistancing for level set-based process simulations with the fast iterative method

The finite iterative method is compared to an industry-hardened fast marching method for accelerating the redistancing step essential for Level Set-based process simulations in the area of technology computer-aided design. We discuss our implementation of the finite iterative method and depict extensions to improve the method for process simulations, in particular regarding stability. Contrary to previously published work, we investigate real-world structures with varying resolutions, originating from the area of process simulation. The serial execution performance as well as error norms are used to compare our approach with an industry-hardened fast marching method implementation. Parallel scalability is discussed based on a shared-memory OpenMP implementation. We show that our approach of the finite iterative method is an excellent candidate for accelerating Level Set-based process simulations, as it offers considerable performance gains both in serial and parallel execution mode, albeit being inferior with respect to accuracy.     

Enhancing the calculation accuracy of performance characteristics of power-generating units by correcting general measurands based on matching energy balances

General principles of a procedure for matching energy balances of thermal power plants (TPPs), whose use enhances the accuracy of information-measuring systems (IMSs) during calculations of performance characteristics (PCs), are stated. To do this, there is the possibility for changing values of measured and calculated variables within intervals determined by measurement errors and regulations. An example of matching energy balances of the thermal power plants with a T-180 turbine is made. The proposed procedure allows one to reduce the divergence of balance equations by 3–4 times. It is shown also that the equipment operation mode affects the profit deficiency. Dependences for the divergence of energy balances on the deviation of input parameters and calculated data for the fuel economy before and after matching energy balances are represented.     

Improving sequencing by tunneling with multiplexing and cross-correlations

Sequencing by tunneling is a next-generation approach to read single-base information using electronic tunneling transverse to the single-stranded DNA (ssDNA) backbone while the latter is translocated through a narrow channel. The original idea considered a single pair of electrodes to read out the current and distinguish the bases [1, 2]. Here, we propose an improvement to the original sequencing by tunneling method, in which \(N\) pairs of electrodes are built in series along a synthetic nanochannel. While the ssDNA is forced through the channel using a longitudinal field it passes by each pair of electrodes for long enough time to gather a minimum of \(m\) tunneling current measurements, where \(m\) is determined by the level of sequencing error desired. Each current time series for each nucleobase is then cross-correlated together, from which the DNA bases can be distinguished. We show using random sampling of data from classical molecular dynamics, that indeed the sequencing error is significantly reduced as the number of pairs of electrodes, \(N\) , increases. Compared to the sequencing ability of a single pair of electrodes, cross-correlating \(N\) pairs of electrodes exponentially improves this sequencing ability due to the approximate log-normal nature of the tunneling current probability distributions. We have also used the Fenton–Wilkinson approximation to analytically describe the mean and variance of the cross-correlations that are used to distinguish the DNA bases. The method we suggest is particularly useful when the measurement bandwidth is limited, allowing a smaller electrode gap residence time while still promising to consistently identify the DNA bases correctly.     

A new modeling and placement of shunt FACTS devices in the secondary voltage regulation environment

Recently, the Secondary Voltage Regulation (SVR) is installed in some power systems in order to ensure the coordination voltage control devices. In other hand, the shunt FACTS devices such as the Static Var Compensator (SVC) and the STATic COMpensator (STATCOM) are extensively used for the local voltage control without any coordination with other voltage control devices, without any reciprocal coordination. In this paper, new models of SVC and STATCOM are proposed to be adopted in power flow models that include the SVR. The proposed models are implemented and tested on a model of the Italian power system. Furthermore, a new method based on sensitivity analysis is proposed to find the most sensitive placements for the installation of SVC and STATCOM. The results obtained show the highly computational performance of the propose models and also the effectiveness of the sensitivity analysis to find the best placements of SVC and STATCOM taking into account the SVR.