scholarly journals 3D Multi-Beam and Null Synthesis by Phase-Only Control for 5G Antenna Arrays

Electronics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 656 ◽  
Author(s):  
Massimiliano Comisso ◽  
Gabriele Palese ◽  
Fulvio Babich ◽  
Francesca Vatta ◽  
Giulia Buttazzoni
Keyword(s):  
Antenna Arrays ◽  
Computational Cost ◽  
Three Dimensional ◽  
Arbitrary Geometry ◽  
Numerical Examples ◽  
Control Approach ◽  
Fifth Generation ◽  
Conformal Arrays ◽  
Necessary Constraints ◽  
Low Computational Cost

This paper presents an iterative algorithm for the synthesis of the three-dimensional (3D) radiation pattern generated by an antenna array of arbitrary geometry. The algorithm is conceived to operate in fifth-generation (5G) millimeter-wave scenarios, thus enabling the support of multi-user mobile streaming and massive peer-to-peer communications, which require the possibility to synthesize 3D patterns with wide null regions and multiple main beams. Moreover, the proposed solution adopts a phase-only control approach to reduce the complexity of the feeding network and is characterized by a low computational cost, thanks to the closed-form expressions derived to estimate the phase of each element at the generic iteration. These expressions are obtained from the minimization of a weighted cost function that includes all the necessary constraints. To finally check its versatility in a 5G environment, the developed method is validated by numerical examples involving planar and conformal arrays, considering desired patterns with different numbers of main beams and nulls.

scholarly journals A Comparison of Splitting Techniques for 3D Complex Padé Fourier Finite Difference Migration

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Jessé C. Costa ◽  
Débora Mondini ◽  
Jörg Schleicher ◽  
Amélia Novais
Keyword(s):  
Wave Equation ◽  
Finite Difference ◽  
Computational Cost ◽  
Three Dimensional ◽  
Depth Level ◽  
Numerical Examples ◽  
The Cost ◽  
Comparable Quality ◽  
3D Problem ◽  
Dimensional Wave

Three-dimensional wave-equation migration techniques are still quite expensive because of the huge matrices that need to be inverted. Several techniques have been proposed to reduce this cost by splitting the full 3D problem into a sequence of 2D problems. We compare the performance of splitting techniques for stable 3D Fourier finite-difference (FFD) migration techniques in terms of image quality and computational cost. The FFD methods are complex Padé FFD and FFD plus interpolation, and the compared splitting techniques are two- and four-way splitting as well as alternating four-way splitting, that is, splitting into the coordinate directions at one depth and the diagonal directions at the next depth level. From numerical examples in homogeneous and inhomogeneous media, we conclude that, though theoretically less accurate, alternate four-way splitting yields results of comparable quality as full four-way splitting at the cost of two-way splitting.

Real Gas Effects in Turbomachinery Flows: A Computational Fluid Dynamics Model for Fast Computations

2004 ◽  
Vol 126 (2) ◽  
pp. 268-276 ◽  
Author(s):  
Paolo Boncinelli ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Massimiliano Cecconi ◽  
Carlo Cortese
Keyword(s):  
Fluid Dynamic ◽  
Computational Cost ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Design Tool ◽  
Navier Stokes ◽  
Computational Time ◽  
Real Gas ◽  
Real Gas Effects ◽  
Low Computational Cost

A numerical model was included in a three-dimensional viscous solver to account for real gas effects in the compressible Reynolds averaged Navier-Stokes (RANS) equations. The behavior of real gases is reproduced by using gas property tables. The method consists of a local fitting of gas data to provide the thermodynamic property required by the solver in each solution step. This approach presents several characteristics which make it attractive as a design tool for industrial applications. First of all, the implementation of the method in the solver is simple and straightforward, since it does not require relevant changes in the solver structure. Moreover, it is based on a low-computational-cost algorithm, which prevents a considerable increase in the overall computational time. Finally, the approach is completely general, since it allows one to handle any type of gas, gas mixture or steam over a wide operative range. In this work a detailed description of the model is provided. In addition, some examples are presented in which the model is applied to the thermo-fluid-dynamic analysis of industrial turbomachines.

Generating Chaos from Two Three-Dimensional Rigorous Linear Systems via a Novel Switching Control Approach

2016 ◽  
Vol 26 (13) ◽  
pp. 1650212 ◽  
Author(s):  
Changchun Sun ◽  
Qicheng Xu
Keyword(s):  
Equilibrium Point ◽  
Linear Systems ◽  
Three Dimensional ◽  
Constant Term ◽  
Switching Control ◽  
Numerical Examples ◽  
Absolute Value ◽  
Control Approach ◽  
Switching Law ◽  
Dynamical Behaviors

By constructing two three-dimensional (3D) rigorous linear systems, a novel switching control approach for generating chaos from two linear systems is presented. Two 3D linear systems without any constant term have only one common equilibrium point that is the origin. By employing an absolute-value switching law, chaos can be generated by switching between two linear systems. Basic dynamical behaviors of the systems are investigated in detail. Numerical examples illustrate the effectiveness of the presented approach.

Three-Dimensional Vibration of Fluid-Conveying Laminated Composite Cylindrical Shells with Piezoelectric Layers

2019 ◽  
Vol 19 (03) ◽  
pp. 1950026
Author(s):  
Seyed Mohammad Miramini ◽  
Abdolreza Ohadi
Keyword(s):  
Cylindrical Shells ◽  
Computational Cost ◽  
Three Dimensional ◽  
Laminated Composite ◽  
Theory Of Elasticity ◽  
Flowing Fluid ◽  
Piezoelectric Layers ◽  
Elastic Layers ◽  
First Time ◽  
Low Computational Cost

Cylindrical shells containing flowing fluid have wide applications in various industries. They can be enhanced as smart structures through inclusion of piezoelectric layers, of which the dynamic behavior, however, has not been fully understood. In this paper, the vibration and dynamic analysis of a laminated composite hollow cylinder with piezoelectric layers, subjected to an internal incompressible fluid flow is investigated. It is assumed that the shell is simply supported and the fluid is inviscid and irrotational. The differential equations of the elastic layers, piezoelectric layers, and flowing fluid are derived by the three-dimensional (3D) theory of elasticity, theory of piezoelectricity, and potential flow theory, respectively. A well-known recursive method is applied and extended for the first time to solve the fluid-conveying pipes using 3D theory. This approach makes it possible for the solutions to converge to the exact ones with reasonable computational cost. After validating the results against those available in the literature, the vibrational behavior of the system is examined for various cases with the effect of each parameter investigated. Also, the influence of fluid on the vibration and stability of the shell has been analyzed. The present method can be used to analyze and design hybrid shells conveying fluid with high accuracy and low computational cost.

scholarly journals Numerical Solution of Linear Volterra Integral Equation Systems of Second Kind by Radial Basis Functions

Mathematics ◽  
2022 ◽  
Vol 10 (2) ◽  
pp. 223
Author(s):  
Pedro González-Rodelas ◽  
Miguel Pasadas ◽  
Abdelouahed Kouibia ◽  
Basim Mustafa
Keyword(s):  
Integral Equation ◽  
Radial Basis Functions ◽  
Volterra Integral Equation ◽  
Computational Cost ◽  
Basis Functions ◽  
Numerical Examples ◽  
Acceptable Accuracy ◽  
Convergence Results ◽  
Radial Basis ◽  
Low Computational Cost

In this paper we propose an approximation method for solving second kind Volterra integral equation systems by radial basis functions. It is based on the minimization of a suitable functional in a discrete space generated by compactly supported radial basis functions of Wendland type. We prove two convergence results, and we highlight this because most recent published papers in the literature do not include any. We present some numerical examples in order to show and justify the validity of the proposed method. Our proposed technique gives an acceptable accuracy with small use of the data, resulting also in a low computational cost.

Hertz Contact at the Nanoscale with a 3D Multiscale Model

2016 ◽  
Vol 846 ◽  
pp. 306-311 ◽  
Author(s):  
Jie Zhang ◽  
Guillaume Michal ◽  
Ahn Kiet Tieu ◽  
Hong Tao Zhu ◽  
Guan Yu Deng
Keyword(s):  
Computational Cost ◽  
Three Dimensional ◽  
Computation Time ◽  
Multiscale Model ◽  
Md Simulations ◽  
Normal Displacement ◽  
Contact Radius ◽  
Asperity Contact ◽  
Fem Model ◽  
Low Computational Cost

This paper presents a three-dimensional multiscale computational model, which is proposed to combine the simplicity of FEM model and the atomistic interactions between two solids. A significant advantage of the model is that atoms are populated in the contact regions, which saves significant computation time compared to fully MD simulations. The model is used in the case of asperity contact. The normal displacement, contact radius and pressure distribution are compared with those from Hertz’s solution and atomistic simulations in the literature. Some important features of nanoscale contacts obtained by MD simulations can be caught by the model with acceptable accuracy and low computational cost.

scholarly journals Phase-Only Antenna Array Reconfigurability with Gaussian-Shaped Nulls for 5G Applications

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Giulia Buttazzoni ◽  
Massimiliano Comisso ◽  
Federico Ruzzier ◽  
Roberto Vescovo
Keyword(s):  
Antenna Arrays ◽  
Base Stations ◽  
Planar Antenna ◽  
Fast Computation ◽  
Angular Dispersion ◽  
Arbitrary Geometry ◽  
Concentric Ring ◽  
Control Approach ◽  
The Cost ◽  
Successive Projections

This paper presents a fast iterative method for the synthesis of linear and planar antenna arrays of arbitrary geometry that provides pattern reconfigurability for 5G applications. The method enables to generate wide null regions shaped according to a Gaussian distribution, which complies with recent measurements on millimeter-wave (mmWave) angular dispersion. A phase-only control approach is adopted by moving from the pattern provided by a uniformly excited array and iteratively modifying the sole phases of the excitations. This allows the simplification of the array feeding network, hence reducing the cost of realization of 5G base stations and mobile terminals. The proposed algorithm, which is based on the method of successive projections, relies on closed-form expressions for both the projectors and the null positions, thus allowing a fast computation of the excitation phases at each iteration. The effectiveness of the proposed solution is checked through numerical examples compliant with 5G mmWave scenarios and involving linear and concentric ring arrays.

scholarly journals Three-Dimensional Complex Padé FD Migration: Splitting and Corrections

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
D. Mondini ◽  
J. C. Costa ◽  
J. Schleicher ◽  
A. Novais
Keyword(s):  
Wave Propagation ◽  
Wave Equation ◽  
Computational Cost ◽  
Three Dimensional ◽  
Cost Effective ◽  
Effective Strategy ◽  
Depth Level ◽  
Numerical Examples ◽  
3D Problem ◽  
Dimensional Wave

Three-dimensional wave-equation migration techniques are still quite expensive because of the huge matrices that need to be inverted. Several techniques have been proposed to reduce this cost by splitting the full 3D problem into a sequence of 2D problems. To reduce errors, the Li correction is applied at regular multiples of depth extrapolation increment. We compare the performance of splitting techniques in wave propagation for 3D finite-difference (FD) migration in terms of image quality and computational cost. We study the behaviour of the complex Padé approximation in combination with two- and alternating four-way splitting, that is, splitting into the coordinate directions at one depth and the diagonal directions at the next depth level. We also extend the Li correction for use with the complex Padé expansion and diagonal directions. From numerical examples in inhomogeneous media, we conclude that alternate four-way splitting is the most cost-effective strategy to reduce numerical anisotropy in complex Padé 3D FD migration.

A Filter-Based Control Approach to Reduce Payload Oscillations in Hydraulic Cranes

2016 ◽  
Author(s):  
Riccardo Bianchi ◽  
Guido Francesco Ritelli ◽  
Andrea Vacca
Keyword(s):  
Hydraulic System ◽  
Computational Cost ◽  
Pressure Sensors ◽  
Limited Attention ◽  
Frequency Transformation ◽  
Control Approach ◽  
Hydraulic Machines ◽  
Load Handling ◽  
Low Computational Cost ◽  
Different Levels

Vibrations in load handling machines can manifest at different levels: at the structure of the machine directly connected to the hydraulic actuators; at the cabin of the machine; or — for machines carrying payload not rigidly connected to the structure — at the payload. These oscillations negatively affect productivity, safety and operator comfort. Several techniques have been proposed to smooth the operation of the mechanical arms of hydraulic machines, but limited attention was so far dedicated specifically to the oscillations of the payload. This paper introduces a frequency-based approach to reduce payload oscillation applicable for load handling machines. The proposed controller generates proper signal to the flow control valves of the hydraulic system, on the basis on the frequency analysis of pressure sensors used as feedback. The controller is composed by a series of dynamic peak filters. A first stage of frequency transformation through the FFT identifies the payload frequency and adjusts the poles of the peak filter. Then, a modulation stage is used to select the proper harmonic suitable to quantify the payload oscillation. Another peak filter enables the generation of the control. This controller has a low computational cost and it is suitable for the implementation to industrial controllers. After describing the controller, the paper presents experimental results suitable to quantify the effectiveness of the proposed procedure, considering a particular truck mounting crane available at the authors’ research center.

Real Gas Effects in Turbomachinery Flows: A CFD Model for Fast Computations

2003 ◽  
Author(s):  
Paolo Boncinelli ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Massimiliano Cecconi ◽  
Carlo Cortese
Keyword(s):  
Fluid Dynamic ◽  
Computational Cost ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Design Tool ◽  
Navier Stokes ◽  
Computational Time ◽  
Real Gas ◽  
Real Gas Effects ◽  
Low Computational Cost

A numerical model was included in a three-dimensional viscous solver to account for real gas effects in the compressible Reynolds Averaged Navier-Stokes (RANS) equations. The behavior of real gases is reproduced by using gas property tables. The method consists of a local fitting of gas data to provide the thermodynamic property required by the solver in each solution step. This approach presents several characteristics which make it attractive as a design tool for industrial applications. First of all, the implementation of the method in the solver is simple and straightforward, since it does not require relevant changes in the solver structure. Moreover, it is based on a low-computational-cost algorithm, which prevents a considerable increase in the overall computational time. Finally, the approach is completely general, since it allows one to handle any type of gas, gas mixture or steam over a wide operative range. In this work a detailed description of the model is provided. In addition, some examples are presented in which the model is applied to the thermo-fluid-dynamic analysis of industrial turbomachines.

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