Simulation Of Array Research Articles

Design of novel high speed parallel prefix adder

Adders are crucial logical building blocks found almost in all the modern electronic system designs. In the adder architecture design, the fundamental issue is the propagation latency in the carry chain. As the length of the input operands increases, the length of the carry chain along with it. Parallel prefix adders, which address the problem of carry propagation in adders, are the most efficient adder topologies for hardware implementation. However, delay reduction still could be achieved for very high speed applications. Hence, in this paper design of 16bit novel parallel prefix adder is proposed and compared against the existing parallel prefix adder architectures. The design and simulation are carried out using xilinx vivado for field- programmable gate array (FPGA) simulation and Cadence® for ASIC. The results of ASIC implementation demonstrate 17.8% delay reduction while compared to sparse kogge-stone adder.

Antenna Arrangement in UWB Helmet Brain Applicators for Deep Microwave Hyperthermia.

Deep microwave hyperthermia applicators are typically designed as narrow-band conformal antenna arrays with equally spaced elements, arranged in one or more rings. This solution, while adequate for most body regions, might be sub-optimal for brain treatments. The introduction of ultra-wide-band semi-spherical applicators, with elements arranged around the head and not necessarily aligned, has the potential to enhance the selective thermal dose delivery in this challenging anatomical region. However, the additional degrees of freedom in this design make the problem non-trivial. We address this by treating the antenna arrangement as a global SAR-based optimization process aiming at maximizing target coverage and hot-spot suppression in a given patient. To enable the quick evaluation of a certain arrangement, we propose a novel E-field interpolation technique which calculates the field generated by an antenna at any location around the scalp from a limited number of initial simulations. We evaluate the approximation error against full array simulations. We demonstrate the design technique in the optimization of a helmet applicator for the treatment of a medulloblastoma in a paediatric patient. The optimized applicator achieves 0.3 °C higher T90 than a conventional ring applicator with the same number of elements.

Analysis and Simulation of a Sequential Rotationally Excited Circular Polarized Multi-Dipole Array for a Bi-Static Antenna GPR for Deep Exploration

As an effective active remote sensing technology for the exploration of shallow underground targets, ground-penetrating radar (GPR) is a detection method that can be used to obtain information about the characteristics of underground targets by transmitting an electromagnetic wave from an antenna and analyzing the propagation of the electromagnetic wave underground. Due to the frequency (1 MHz–3 GHz) of GPRs, the depth of geological exploration is shallow (0.1–30 m). In order to penetrate the deeper Earth, it is necessary to increase the size of the antenna in accordance with the wavelength ratio and, thus, reduce the radiation frequency. For most bi-static antenna GPRs, a dipole antenna is used as the transmitting antenna and another antenna device is used as a receiving antenna, with both being horizontally linearly polarized (LP) antennas. In some cases, such a design can cause problems, such as the multi-path effect and polarization mismatching. When a GPR is used for deep exploration, increased numbers of errors and greater signal attenuation during data reception and processing often occur. In contrast, at the radiation source, with the use of large-aperture multiple-dipole antennas and multi-channel sequential rotational excitation, the electromagnetic wave can radiate in the form of circular polarization at a low frequency. In the receiving antenna, the issues caused by the multi-path effect and polarization mismatching can be addressed, even if LP antennas are used. A novel sequential rotationally excited (SRE) circularly polarized (CP) multiple-dipole array for a bi-static antenna GPR for deep exploration is proposed in this paper. A large-aperture CP multiple-dipole array is used instead of a small-size LP dipole antenna. The analysis and simulation results demonstrated that, comparing circular polarization and linear polarization with the premise of the same transmitting power, the SRE CP multiple-dipole antenna array radiation source achieved a significant enhancement (about 7 dB) in the signal-to-noise ratio (SNR) as the radiant energy was collected at the receiving antenna. More importantly, by reducing the exploration frequency to 10 KHz, the exploration depth could also be greatly increased by about tenfold.

Theoretical research and simulation of GaAs nanowire arrays in reflection-type photon-enhanced thermionic emission solar converters

In this paper, GaAs was used as the cathode of the photon-enhanced thermionic emission (PETE) solar converter. Based on the one-dimensional continuity equation and boundary conditions, a reflection-type PETE theoretical model was established to simulate the effects of solar concentration, electron affinity, cathode temperature and electron recombination velocity on the current density and the conversion efficiency. For optimizing the performance of the solar converter, we used GaAs nanowire (NW) arrays as the cathode and calculated the influences of NW arrays’ period, duty ratio, and height on the absorbance and the conversion efficiency by combining the theoretical model with the three-dimensional finite-difference time-domain (3D FDTD) method. The results were used to design the structure size of NW arrays, which improved the conversion efficiency of the solar converter to 23.07%. It shows that the GaAs NW arrays are promising PETE cathode materials.

Efficient Semi-Analytical Method for the Analysis of Large Finite Connected Slot Arrays

We present an efficient method for the analysis of finite connected slot arrays in the presence of stratified media. The formulation is based on a spectral method of moments, where only one basis function is considered for each array element and one for each slot edge. An expression for the mutual impedance is derived in terms of a double spectral integral. Asymptotic extraction techniques are employed to largely reduce the computation time of one of the spectral integrals. For the other integral, when a guided wave contribution dominates the mutual coupling between two array elements, the result can be approximated as the residue of the spectral polar singularity, providing a closed-form solution of the coupling for elements at electrically large distances. The complete method enables simulations of entire finite arrays with hundreds or even thousands of elements in minutes. The same structure would require impractical computation time when analyzed with general-purpose commercial software. The method allows estimating the performance of finite connected arrays. This is particularly relevant because wideband connected arrays are known to exhibit higher edge effects compared to narrowband arrays, due to the high interelement mutual coupling.

Vacancy defects impede the transition from peapods to diamond: a neuroevolution machine learning study.

Exploration of novel carbon allotropes has been a central subject in materials science, in which carbon peapods hold great potential as a precursor for the development of new carbon allotropes. To enable precise large-scale molecular dynamics simulations, we develop a high-accurate and low-cost machine-learned potential (MLP) for carbon materials using the neuroevolution potential framework. Based on the MLP, we conduct an investigation into the structural transitions of peapod arrays under high-temperature and high-pressure conditions and disclose the impact of vacancy defects. Defects promote the transition from the ordered crystalline structure to the disordered amorphous structure in peapods at low temperatures, while impeding the transition to the ordered diamond structure. Benefiting from the accurate MLP, we are able to reproduce the experimentally observed carbon structures in numerical simulations. We build a diagram summarizing all the structures that appear in the compression simulation of peapod arrays at various temperatures. The present work not only discloses the underlying mechanism of structural transitions from carbon peapods into various functional carbon materials, but also provides a high-accurate and low-cost interatomic potential that shall be valuable in the exploration of novel carbon allotropes.

Digital Filter Architecture Based on Modified Winograd Method F(2× 2, 5× 5) and Residue Number System

Improving the characteristics of digital signal processing devices is an important task in many practical problems. The paper proposes the architecture of a two-dimensional digital filter with a 5×5 mask, in which calculations are performed according to the Winograd method in the Residue Number System (RNS) with moduli of a special type. Theoretical analysis and hardware Field-Programmable Gate Array simulation are presented. The results show that the fragment throughput fr/s (number of fragments per second) of the device is 29.6% – 724.7% higher than state-of-the-art solutions. This is achieved by the combination of the Winograd method, which reduces the number of multiplications, with the RNS arithmetic, which performs addition and multiplication under smaller operands in parallel. However, our experiments showed that the proposed method requires up to 2.54% – 11.01% more Look-Up Tables and 3.58% – 19.83% higher power consumption compared to known analogues.

Small-Signal Stability Analysis With Approximated PV Model for Solar Array Simulator

Solar array simulators (SAS) equipment is used to mimic the characteristics curve for photovoltaic (PV) generators. However, an in-depth stability analysis of the SAS with respect to its reference signal is yet to be investigated. This is due to implicit and nonlinear mapping equations used to describe the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$I\text{--}V$</tex-math></inline-formula> curve, which complicates the loop analysis. Our study proposes a super-elliptical method to approximate the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$I\text{--}V$</tex-math></inline-formula> characteristic curve and provide an explicit PV equation that is straightforward to manipulate. Furthermore, this approximate model is then used for the dynamic performance assessment for the typical control architecture. Based on the comparative study using the approximate mode either in the theoretical analysis and the experimental verification, the resistance-sensing control scheme tends to reduce the effect of loop interactions in the SAS, thereby showing more consistent dynamic performance than the other control structure.

A fast-modeling algorithm to predict the thermo-field emission and thermal stability of field emitter arrays

In the last decades, numerical simulation has become a precious tool to assist the design and study of electron sources based on regular arrays of field emitters. Simulations of field emitter arrays (FEAs) require 3D treatment to account for the interactions between neighbor emitters. Therefore, modeling the thermal evolution of FEAs involves high computational resources due to the multi-physics approach and time dependency. The present paper proposes an algorithm which gives a fast prediction of the self-heating of a large array of N axisymmetric field emitters. It consists in finding for each emitter the equivalent 2D axisymmetric situation yielding the same electron current at 300 K as in the 3D array. The 3D modeling is thus efficiently split into N simulations in 2D, with a significant computation time reduction by at least one order of magnitude. The proof of concept uses 3×3 arrays of ideal emitters. Our results show a correct prediction, within a few percent, of the array thermo-field current and maximum temperature—two quantities of high interest for thermal failure and breakdown voltage considerations. The algorithm paves the way for including thermal effects in future optimization studies of realistic FEAs.

Microtubule nucleation complex behavior is critical for cortical array homogeneity and xylem wall patterning

Plant cell walls are versatile materials that can adopt a wide range of mechanical properties through controlled deposition of cellulose fibrils. Wall integrity requires a sufficiently homogeneous fibril distribution to cope effectively with wall stresses. Additionally, specific conditions, such as the negative pressure in water transporting xylem vessels, may require more complex wall patterns, e.g., bands in protoxylem. The orientation and patterning of cellulose fibrils are guided by dynamic cortical microtubules. New microtubules are predominantly nucleated from parent microtubules causing positive feedback on local microtubule density with the potential to yield highly inhomogeneous patterns. Inhomogeneity indeed appears in all current cortical array simulations that include microtubule-based nucleation, suggesting that plant cells must possess an as-yet unknown balancing mechanism to prevent it. Here, in a combined simulation and experimental approach, we show that a limited local recruitment of nucleation complexes to microtubules can counter the positive feedback, whereas local tubulin depletion cannot. We observe that nucleation complexes preferentially appear at the plasma membrane near microtubules. By incorporating our experimental findings in stochastic simulations, we find that the spatial behavior of nucleation complexes delicately balances the positive feedback, such that differences in local microtubule dynamics-as in developing protoxylem-can quickly turn a homogeneous array into a banded one. Our results provide insight into how the plant cytoskeleton has evolved to meet diverse mechanical requirements and greatly increase the predictive power of computational cell biology studies.

3-D Ray Launching MIMO Channel Geometric Estimation

The complete multiple-input–multiple-output (MIMO) channel simulation in deterministic techniques can be a computationally intensive task, due to the inherent scenario's complexity and number of antennas. The spatial coherence among MIMO elements is a reasonable assumption to approximate the channel from a single point simulation. In this letter, a novel method to incorporate a geometrical approximation of the MIMO channel into a three-dimensional ray launching (3D-RL) algorithm is presented. The method is antenna type independent and the orientation of the array is embedded in the antenna representation. Relevant information of the MIMO channel characteristics like the root mean square (rms) delay spread, the maximum delay spread, phase and channel capacity are obtained and compared with the full 3D-RL simulation of the entire MIMO array, achieving 93.4% reduction in computational time.

28 nm HKMG-Based Current Limited FeFET Crossbar-Array for Inference Application

This article reports a novel ferroelectric field-effect transistor (FeFET)-based crossbar array cascaded with an external resistor. The external resistor is shunted with the column of the FeFET array, as a current limiter and reduces the impact of variations in drain current ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{d}$ </tex-math></inline-formula> ), especially in a low threshold voltage (LVT) state. We have designed crossbar arrays of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times8$ </tex-math></inline-formula> sizes and performed multiply-and-accumulate (MAC) operations. Furthermore, we have evaluated the performance of the current limited FeFET crossbar array in system-level applications. Finally, the system-level performance evaluation was done by neuromorphic simulation of the resistor-shunted FeFET crossbar array. The crossbar array achieved software-comparable inference accuracy (~97%) for National Institute of Standards and Technology (MNIST) datasets with multilayer perceptron (MLP) neural network, whereas the crossbar arrays built solely with FeFETs failed to learn, yielding only 9.8% accuracy.

5.8 GHz Circularly Polarized Rectangular Microstrip Antenna Arrays simulation for Point-to-Point Application

In this paper, the design and simulation of rectangular microstrip antenna arrays for improving antenna gain is performed for point-to-point application. The proposed design is composed of four elements microstrip antenna with an array configuration operating at 5.8 GHz. Each element is constructed from four truncated arrays radiating elements and an inclined slot on each patch which capable to achieve circular polarized capability. The design of the 2x1 and 2x2 of rectangular microstrip array antenna was implemented from the designed of single rectangular patch antenna as the basic building element. The designed 2x1 and 2x2 array were fed by microstrip transmission line which applied a technique of quarter wave impedance matching. The antenna design was etched on Rogers RT 5880 substrate with 2.1 and 1.53 mm of dielectric constant and thickness respectively. All the designed structure were simulated in CST software. The main results of the designed antennas were compared in terms of gain, axial ratio and return loss. Based on the return loss simulation results, the designed antennas resonated exactly at the desired resonant frequency of 5.8 GHz which indicates good antenna designs. Compared to the single patch antenna having an antenna gain of 8.26 dB, the 2x1 and 2x2 arrays achieved a gain of 10.24 dB and 13.29 dB respectively. The results show that the designed rectangular microstrip antenna arrays have an improved gain performance over the single patch antenna.

Large-eddy simulation of a wind-turbine array subjected to active yaw control

Abstract. This study validates large-eddy simulation (LES) for predicting the flow through a wind turbine array subjected to active yaw control. The wind turbine array consists of three miniature wind turbines operated in both non-yawed and yawed configurations under full-wake and partial-wake conditions, for which wind tunnel flow measurements are available. The turbine-induced forces are parametrised by three different models: the standard actuator disk model (ADM-std), the blade element actuator disk model (ADM-BE), also referred to as the rotational actuator disk model (ADM-R), and the actuator line model (ALM). The time-averaged turbine power outputs and the profiles of the wake flow statistics (normalised streamwise mean velocity and streamwise turbulence intensity) obtained from the simulations using the ADM-std, the ADM-BE and the ALM are compared with experimental results. We find that simulations using the ADM-BE and ALM yield flow statistics that are in good agreement with the wind-tunnel measurements for all the studied configurations. In contrast, the results from LES with the ADM-std show discrepancies with the measurements obtained under yawed and/or partial-wake conditions. These errors are due to the fact that the ADM-std assumes a uniform thrust force, thus failing to capture the inherently inhomogeneous distribution of the turbine-induced forces under partial wake conditions. In terms of power prediction, we find that LES using the ADM-BE yields better power predictions than the ADM-std and the ALM in the cases considered in this study. As a result, we conclude that LES using the ADM-BE provides a good balance of accuracy and computational cost for simulations of the flow through wind farms subjected to AYC.

Unsupervised learning of Rydberg atom array phase diagram with Siamese neural networks

We introduce an unsupervised machine learning method based on Siamese neural networks (SNNs) to detect phase boundaries. This method is applied to Monte-Carlo simulations of Ising-type systems and Rydberg atom arrays. In both cases the SNN reveals phase boundaries consistent with prior research. The combination of leveraging the power of feed-forward neural networks, unsupervised learning and the ability to learn about multiple phases without knowing about their existence provides a powerful method to explore new and unknown phases of matter.

An Inhomogeneous Plane-Wave Based Single-Level Fast Direct Solver for the Scattering Analysis of Extremely Large Antenna Arrays

A semianalytic single-level fast direct solver (FDS) is presented for the method-of-moments (MoM) analysis of large planar antenna arrays with up to few thousands of complex elements on current desktop computers. Assuming a partition of the impedance matrix, the proposed scheme factorizes the near-field blocks via a singular value decomposition (SVD)-based low-rank approximation and the intermediate-field blocks via an analytical inhomogeneous plane-wave (IPW) expansion. The near- and intermediate-field bases are then unified to leverage the Woodbury formula for the inversion. The solutions for the excitation of each array ports are obtained at once with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$O(N^{15/7} \ln ^{3} N)$ </tex-math></inline-formula> computational cost and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$O(N^{11/7} \ln N)$ </tex-math></inline-formula> memory for array problems with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> basis functions. The complexities are traced precisely and the error is controlled by means of analytical formulas for the required number of IPWs. The FDS is also combined with a macrobasis function (MBF) approach to deal with antenna geometries containing many subwavelength details. This article includes simulations of regular arrays of about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$169^{2}~3$ </tex-math></inline-formula> -D dipoles and an irregular array composed of seven stations of the low-frequency square kilometer array (SKA) telescope comprising each 256 log-periodic (LP) antennas. The proposed FDS allows the analysis of the coupling effect both within any one station but also between the stations of the telescope, a size and complexity of problem which has not been possible with existing published techniques.

A feasibility study of a small-scale photovoltaic-powered reverse osmosis desalination plant for potable water and salt production in Madura Island: A techno-economic evaluation

• Techno-economic analysis of a small-scale PV-RO desalination plant in Madura Island. • Potable water production of 11.6 m 3 /day with an annual solar contribution of 84 % • The levelized cost of water production using PV-RO desalination plant is 9.0 USD/m 3. • Payback period of PV-RO plant is 4 years for plant lifetime of 25 years. • PV-RO plant usage can increase salt production effectiveness of the salt farmers. The use of reverse osmosis (RO) desalination plant powered by a photovoltaic (PV) system is an attractive solution for small-scale applications in Madura Island (Indonesia). In this paper, the techno-economic feasibility of a small-scale grid-connected PV-RO desalination plant has been carried out in Madura Island for a plant capacity of 11.6 m 3 /day. The RO brine concentrate is utilized for valuable salt production-via-evaporation ponds that allowed the reduction of the required size in the conventional salt evaporation ponds. The steady-state numerical model of the RO desalination plant was used to predict the plant's performance using the characteristics of commercial RO elements. The PV array simulation was carried out using a dynamic modelling and simulation program based on weather data of Madura Island. The result illustrates that the production of potable water and salt using a community-scale grid-connected PV-RO plant is economically viable to be implemented in the region. The payback period of this PV-RO plant is around 4 years for a considered plant lifetime of 25 years with an annual solar contribution of 84 %. The Levelized cost of water production using the PV-RO plant is about 9.0 USD/m 3 which is more cost-effective than the current cost of potable water in the region. Besides, the use of solar-assisted RO desalination plants in water-stressed regions such as Madura Island allows for mitigating the greenhouse gas emissions associated with seawater desalination.

Design and Simulation of a Ring Transducer Array for Ultrasound Retinal Stimulation.

Argus II retinal prosthesis is the US Food and Drug Administration (FDA) approved medical device intended to restore sight to a patient’s blind secondary to retinal degeneration (i.e., retinitis pigmentosa). However, Argus II and most reported retinal prostheses require invasive surgery to implant electrodes in the eye. Recent studies have shown that focused ultrasound can be developed into a non-invasive retinal prosthesis technology. Ultrasound energy focused on retinal neurons can trigger the activities of retinal neurons with high spatial-temporal resolution. This paper introduces a novel design and simulation of a ring array transducer that could be used as non-invasive ultrasonic retinal stimulation. The array transducer is designed in the shape of a racing ring with a hemisphere surface that mimics a contact lens to acoustically couple with the eye via the tear film and directs the ultrasound to avoid the high acoustic absorption from the crystalline lens. We will describe the design methods and simulation of the two-dimensional pattern stimulation. Finally, compared with other existing retinal prostheses, we show that the ultrasound ring array is practical and safe and could be potentially used as a non-invasive retinal prosthesis.

Acoustic Levitation for Large Particle Based on Concave Spherical Transducer Arrays

With the advantages of non-contact, compatibility, no chemical effect and safety, acoustic levitation of object has great potential to apply in chemistry, biology, medicine field and micro robots. Suspension to large particle higher than the half wavelength( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.5\lambda $ </tex-math></inline-formula> ) of sound wave, is a challenge technology in micro-nanoscale manipulation. An increased large quantity probes, double sided and four sided phased array with virtual vortex can provide higher capture power, control ability and stability of particle fixation and the manipulation. However, for a limited confined space, the additional probes and sided phased array emission and receiving device is hard to be established and applied. Additional probes and sided ultrasonic phased array requires higher processing ability of MCU (Micro Control Unit) and the quantities of transducers. Further, multiparticles suspension is rare to be reported. In this study, a relatively simple suspension device of one sided concave spherical transducer array is designed, aiming to levitate a large particle and multi-particles. Based on the one sided acoustic field simulation of ultrasonic array, the optimized structure of open spherical sector (OSS) is constructed to establish levitation device. Experimental platform integrating FPGA controller, amplifier and impedance matching is developed to drive the transducer arrays, where a polystyrene particle with 6 mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.71\lambda $ </tex-math></inline-formula> ) diameter is successfully levitated. The virtual twin trap sound pressure of transducer array is measured to evaluate the particle stability. Experiments demonstrate the correctness of virtual twin trap acoustic field analysis, the feasibility in the manipulation to the large particle and multi-particles by acoustic trap.

Elastic unidirectional cylindrically-symmetric-fiber composites with general radially-variable anisotropic coatings

Differential substitution/coating schemes have been developed to construct various explicit expressions or determining initial-valued ordinary differential equations for the effective elastic cylindrically-symmetric fiber composite problems, which include those with general radially-variable anisotropic coatings. The schemes are stated from Hashin–Rosen-type multi-coated cylinder assemblage micro-geometry and Hill substitution formulae, with differential constructions for generalizations. When the volume proportion of the outermost cylindrical shell increases toward 1, one obtains the respective dilute solutions for the compound inhomogeneities suspended in a major matrix phase. Illustrating numerical comparisons of the predictions from the model and those of finite element simulations for the geometrically-close hexagonal arrays of anisotropic-coating cylinders, with the material data taken from the literature, are presented.