scholarly journals Frequency Diversity Array for Near-Field Focusing

Electronics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 958
Author(s):  
Xu Han ◽  
Shuai Ding ◽  
Yongmao Huang ◽  
Yuliang Zhou ◽  
Huan Tang ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Numerical Methods ◽  
Numerical Optimization ◽  
Near Field ◽  
Optimization Method ◽  
Frequency Diversity ◽  
Initial Amplitude ◽  
Full Wave ◽  
Circular Arrays ◽  
Working Frequency

In this study, a numerical optimization method is proposed to achieve the near-field focusing of square arrays and circular arrays. This method introduced the frequency diversity array (FDA) approach to change the initial amplitude and working frequency. By adjusting the working state of each antenna, the field distribution on any plane can be artificially controlled. To analyze the FDA, a mathematical model for the FDA has been built and the model has been optimized by a numerical algorithm. The results of two different kinds of arrays are verified by numerical methods and full-wave simulation.

scholarly journals Mathematical model for imitation of management of the enterprise’s logistical system

2021 ◽  
Vol 107 ◽  
pp. 10004
Author(s):  
Roman Ivanov ◽  
Yuriy Sherstennikov ◽  
Vasyl Porokhnya ◽  
Tetyana Grynko
Keyword(s):  
Mathematical Model ◽  
Economic Efficiency ◽  
Numerical Optimization ◽  
Optimization Method ◽  
Retail Trade ◽  
Market Demand ◽  
Logistics System ◽  
Production Activity ◽  
Potential Demand ◽  
The Mathematical Model

The study is devoted to solving the scientific problem of optimizing the retail trade in the production and sale of two types of products, taking into account the change in potential demand for products. The economic and mathematical model of the production activity of the enterprise was developed taking into account logistics and market demand. The logistics scheme takes into account all the main links of the logistics system, as well as the connections between them. The considered scheme makes it possible to take into account the diversification of products manufactured by the enterprise. The mathematical model is designed for discrete time. A numerical optimization method has been developed for this mathematical model. The optimal solutions for several cases are found and investigated. The dynamics of the main characteristics of drugs was calculated for all considered cases. A comparative analysis of economic efficiency for the studied cases has been performed. The economic efficiency of retail network optimization is proved.

Glycemia monitoring

1998 ◽  
Vol 2 ◽  
pp. 23-30
Author(s):  
Igor Basov ◽  
Donatas Švitra
Keyword(s):  
Diabetes Mellitus ◽  
Mathematical Model ◽  
Numerical Methods ◽  
Differential Equations ◽  
Blood Sugar ◽  
Self Regulation ◽  
Physiological System ◽  
Non Linear ◽  
The Mathematical Model

Here a system of two non-linear difference-differential equations, which is mathematical model of self-regulation of the sugar level in blood, is investigated. The analysis carried out by qualitative and numerical methods allows us to conclude that the mathematical model explains the functioning of the physiological system "insulin-blood sugar" in both normal and pathological cases, i.e. diabetes mellitus and hyperinsulinism.

scholarly journals A theoretical and numerical approach for selecting miniaturized antenna topologies on magneto-dielectric substrates

2015 ◽  
Vol 7 (3-4) ◽  
pp. 369-377 ◽  
Author(s):  
Alex Pacini ◽  
Alessandra Costanzo ◽  
Diego Masotti
Keyword(s):  
Near Field ◽  
Dielectric Materials ◽  
Numerical Approach ◽  
Operating Conditions ◽  
Microwave Range ◽  
Dielectric Substrates ◽  
Full Wave ◽  
Miniaturized Antenna ◽  
Wavelength Radiation ◽  
Definition Of

An increasing interest is arising in developing miniaturized antennas in the microwave range. However, even when the adopted antennas dimensions are small compared with the wavelength, radiation performances have to be preserved to keep the system-operating conditions. For this purpose, magneto-dielectric materials are currently exploited as promising substrates, which allows us to reduce antenna dimensions by exploiting both relative permittivity and permeability. In this paper, we address generic antennas in resonant conditions and we develop a general theoretical approach, not based on simplified equivalent models, to establish topologies most suitable for exploiting high permeability and/or high-permittivity substrates, for miniaturization purposes. A novel definition of the region pertaining to the antenna near-field and of the associated field strength is proposed. It is then showed that radiation efficiency and bandwidth can be preserved only by a selected combinations of antenna topologies and substrate characteristics. Indeed, by the proposed independent approach, we confirm that non-dispersive magneto-dielectric materials with relative permeability greater than unit, can be efficiently adopted only by antennas that are mainly represented by equivalent magnetic sources. Conversely, if equivalent electric sources are involved, the antenna performances are significantly degraded. The theoretical results are validated by full-wave numerical simulations of reference topologies.

Geometric design of a pinion with two circularly arrayed conical teeth for roller drives

2006 ◽  
Vol 220 (9) ◽  
pp. 1405-1412 ◽  
Author(s):  
T-S Lai
Keyword(s):  
Mathematical Model ◽  
Coordinate Transformation ◽  
Geometric Design ◽  
Solid Modelling ◽  
Design Algorithm ◽  
Circular Arrays ◽  
Roller Drive ◽  
New Type ◽  
Design Case ◽  
Envelope Theory

This article presents a mathematical model and geometric design algorithm for a new type of roller drive. The pinion has conical teeth in two circular arrays instead of one. This work is based on coordinate transformation and envelope theory, from which the equation of meshing of the cycloid drive is derived. The pinion profiles are the equidistant curves of the epicycloid profiles except the contour of the pinion conical tooth holes. Although there are twice as many pinion teeth as conventional rollers, their speed ratios are identical. This approach can design roller drives in which the pinion has two circular arrays of conical and cylindrical rollers. On the basis of these results, the corresponding solid modelling is constructed by CAD. Four examples are presented to demonstrate the feasibility of this approach. These examples can be a useful reference as a design case for other tooth profiles.

Nonsmooth Optimization Method for Image Restoration

1995 ◽  
Author(s):  
Kazufumi Ito ◽  
Karl Kunisch
Keyword(s):  
Image Restoration ◽  
Nonsmooth Optimization ◽  
Numerical Optimization ◽  
Augmented Lagrangian ◽  
Energy Criterion ◽  
Optimization Methods ◽  
Optimization Method ◽  
Augmented Lagrangian Methods ◽  
Active Set ◽  
First Order

Abstract In this paper we discuss applications of the numerical optimization methods for nonsmooth optimization, developed in [IK1] for the variational formulation of image restoration problems involving bounded variation type energy criterion. The Uzawa’s algorithm, first order augmented Lagrangian methods and Newton-like update using the active set strategy are described.

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