scholarly journals MULTIVARIABLE CONTROL OF SOLAR BATTERY POWER: ELECTROTECHNICAL COMPLEX AS OBJECT WITH HESSIAN-DRIVEN GRADIENT FLOWS

2021 ◽  
Vol 21 (3) ◽  
pp. 57-65
Author(s):  
A. Sologubov ◽  
◽  
I. Kirpichnikova
Keyword(s):  
Initial Conditions ◽  
Small Neighborhood ◽  
Extremum Seeking ◽  
Transient Processes ◽  
Gradient Flows ◽  
Compact Sets ◽  
Tuning Parameters ◽  
Solar Tracking ◽  
Urgent Task ◽  
The Cost

The paper presents certain development results for the novel extremum seeking controller based on Nesterov’s gradient flows for solar tracking systems. It achieves convergence to an arbitrarily small neighborhood of the set of the cost function optimizers. Our results evident ate that for arbitrarily large compact sets of initial conditions, and arbitrarily small neighborhoods of the optimizer, the controller can be tuned to guarantee convergence taking into account the influence of the Hessian, as well as with tuning parameters that have a fairly clear physical meaning. The influence of the Hessian as a vector field, which is a reflection of the distortion of transient processes in the system, and taking it into account is an urgent task, since it allows for a more flexible impact on the speed of transient processes, and by endowing the system with some damping and smoothing, also for its improved quality.

Cu-doped Co3O4 nanostructures as an efficient non-noble metal electrocatalyst for methanol oxidation in basic solution

2021 ◽  
Author(s):  
Shuang Zhao ◽  
Hui Yang ◽  
Yaru Liu ◽  
Yaodong Xing ◽  
Guangwen Cui ◽  
...  
Keyword(s):  
Methanol Oxidation ◽  
Noble Metal ◽  
Oxidation Reaction ◽  
Rational Design ◽  
Methanol Oxidation Reaction ◽  
Basic Solution ◽  
Urgent Task ◽  
The Cost ◽  
Co3o4 Nanostructures

Rational design of non-noble metal electrocatalysts is an urgent task to lower the cost of electrocatalysts for methanol oxidation reaction (MOR). Herein, mesoporous Cu-Co3O4 electrocatalysts have been prepared by using...

High-order relaxation approaches for adjoint-based optimal control problems governed by nonlinear hyperbolic systems of conservation laws

2016 ◽  
Vol 24 (1) ◽  
Author(s):  
Elimboto M. Yohana ◽  
Mapundi K. Banda
Keyword(s):  
Optimal Control ◽  
Conservation Laws ◽  
Optimal Control Problems ◽  
Initial Conditions ◽  
Hyperbolic Systems ◽  
Control Problems ◽  
Computational Investigation ◽  
Backward Problem ◽  
Systems Of Conservation Laws ◽  
The Cost

AbstractA computational investigation of optimal control problems which are constrained by hyperbolic systems of conservation laws is presented. The general framework is to employ the adjoint-based optimization to minimize the cost functional of matching-type between the optimal and the target solution. Extension of the numerical schemes to second-order accuracy for systems for the forward and backward problem are applied. In addition a comparative study of two relaxation approaches as solvers for hyperbolic systems is undertaken. In particular optimal control of the 1-D Riemann problem of Euler equations of gas dynamics is studied. The initial values are used as control parameters. The numerical flow obtained by optimal initial conditions matches accurately with observations.

scholarly journals A method for estimating Hill function-based dynamic models of gene regulatory networks

2018 ◽  
Vol 5 (2) ◽  
pp. 171226 ◽  
Author(s):  
Faizan Ehsan Elahi ◽  
Ammar Hasan
Keyword(s):  
Gene Regulatory Networks ◽  
Regulatory Networks ◽  
Optimization Problem ◽  
Dynamic Models ◽  
Initial Conditions ◽  
Computational Cost ◽  
Optimization Approach ◽  
Continuous Models ◽  
Gene Regulatory ◽  
The Cost

Gene regulatory networks (GRNs) are quite large and complex. To better understand and analyse GRNs, mathematical models are being employed. Different types of models, such as logical, continuous and stochastic models, can be used to describe GRNs. In this paper, we present a new approach to identify continuous models, because they are more suitable for large number of genes and quantitative analysis. One of the most promising techniques for identifying continuous models of GRNs is based on Hill functions and the generalized profiling method (GPM). The advantage of this approach is low computational cost and insensitivity to initial conditions. In the GPM, a constrained nonlinear optimization problem has to be solved that is usually underdetermined. In this paper, we propose a new optimization approach in which we reformulate the optimization problem such that constraints are embedded implicitly in the cost function. Moreover, we propose to split the unknown parameter in two sets based on the structure of Hill functions. These two sets are estimated separately to resolve the issue of the underdetermined problem. As a case study, we apply the proposed technique on the SOS response in Escherichia coli and compare the results with the existing literature.

A novel adaptive second-order nonsingular terminal sliding mode guidance law design

2020 ◽  
Vol 234 (16) ◽  
pp. 2263-2273
Author(s):  
Shuai Xu ◽  
Min Gao ◽  
Dan Fang ◽  
Yi Wang ◽  
Baochen Li
Keyword(s):  
Finite Time ◽  
Sliding Mode ◽  
Initial Conditions ◽  
Dynamic Control ◽  
Small Neighborhood ◽  
Lyapunov Stability Theory ◽  
Second Order ◽  
Terminal Sliding Mode ◽  
Guidance Law ◽  
Nonsingular Terminal Sliding Mode

Aiming at the problem of missile attacking ground target in pitch plane, combined with a composite fast nonsingular terminal sliding mode, a new adaptive finite-time stable guidance law with attack angle constraint is designed based on the second-order sliding mode control. The improved extended state observer is used to estimate the uncertainties and compensate the control quantity, and the dynamic control gains are designed to avoid the problem about “excessive estimation” of the parameter upper limit. According to the Lyapunov stability theory, it is proved that the system states can converge into a small neighborhood near the equilibrium point in a finite time. Monte Carlo simulation is carried out by randomly generating initial conditions, which proves that the guidance law has strong adaptability to different initial conditions and has good guidance precision.

scholarly journals A Review of Daylighting System: For Prototype Systems Performance and Development

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2863 ◽  
Author(s):  
Allen Jong-Woei Whang ◽  
Tsai-Hsien Yang ◽  
Zhong-Hao Deng ◽  
Yi-Yung Chen ◽  
Wei-Chieh Tseng ◽  
...  
Keyword(s):  
Optical Design ◽  
Controversial Issue ◽  
Tracking Systems ◽  
Valuable Resource ◽  
Research Directions ◽  
Active Systems ◽  
Solar Tracking ◽  
And Performance ◽  
Daylight Performance ◽  
The Cost

Daylighting systems make daylight illuminance possible, and the development of prototype daylighting systems can provide more efficient daylight illuminance. The purpose of this article is to review the development and performance of prototype daylighting systems in the last decade. The passive and active daylighting systems are listed separately and divided into the four categories by the presence and absence of hybrid. Each prototype daylighting system was evaluated in terms of cost and daylight performance and as well as their novel optical design. We evaluated the architecture and daylighting principles of each system by reviewing individual prototype daylighting systems. The cost of prototype systems still poses a challenge to development. How to use passive or active systems in different environments and whether or not electrical lighting assistance is needed is a controversial issue. However, active daylighting systems equipped with solar tracking systems are still mainstream. This research is a valuable resource for daylight researchers and newcomers. It is helpful to understand the advantages of various prototype daylighting systems and commercial daylighting systems that have been developed for many years; moreover, it is also possible to know the research directions suggested by the prototype daylighting systems. These will be of further use in developing innovative and better daylighting systems and designs.

Determination of Hydraulic Permeability Based on the Measurements of Outflow

2015 ◽  
Vol 3 ◽  
pp. 105-116
Author(s):  
Jozef Kačur ◽  
Jozef Minár
Keyword(s):  
Unsaturated Flow ◽  
Dimensional Space ◽  
A Priori ◽  
Hydraulic Permeability ◽  
Infinite Dimensional ◽  
Tuning Parameters ◽  
Finite Dimensional ◽  
Partially Saturated Porous Media ◽  
The Cost

In this paper we present a method for the determination of the hydraulic permeability for flow in partially saturated porous media. The dependence of hydraulic permeability on effective saturation is not assumed to be a member of any specific finite dimensional class of functions (e.g. vanGenuchten-Mualem, Burdin-Mualem, Brook-Corey). Instead, an infinite dimensional space of functions with limited a priori assumptions (e.g. smoothness, monotonicity) is considered. Consequently, we face a more challenging problem compared to the finite-dimensional case, in which only few tuning parameters need to be determined. We consider the case of 1D unsaturated flow and assume that the data are collected at the outflow of the sample. The hydraulic permeability is determined in an iterative way. We minimize the cost functional reflecting the discrepancy between the measured and computed data. In doing so, we use the Gateaux differential to obtain the direction of the descent.

Computational Fluid Dynamics in Undergraduate Engineering Education: A Short Introductory Tutorial to OpenFOAM

2016 ◽  
Author(s):  
Ivaylo Nedyalkov ◽  
Martin Wosnik
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Open Source ◽  
Undergraduate Students ◽  
Turbulence Modeling ◽  
Initial Conditions ◽  
Specific Flow ◽  
Undergraduate Engineering ◽  
Wide Range ◽  
The Cost

Computational Fluid Dynamics (CFD) has become a widely used tool in industry as the cost for simulations is usually lower than the cost for multiple experiments. CFD is an effective tool for comparing design alternatives, investigating specific flow features and in some cases it may be the only feasible option for studying engineering flows. As a result, the demand for mechanical engineers with CFD skills keeps increasing. Nevertheless CFD is still not adequately presented in undergraduate engineering curricula, which can lead to expensive mistakes, if for example it is relied on without understanding its limitations. One excellent platform for CFD, which can be introduced to fluid mechanics classes, is the open-source environment OpenFOAM, which is widely used in both academia and industry. In addition to being open-source, OpenFOAM code can be viewed and modified by the user, and a wide range of modules for OpenFOAM are available with new modules being developed constantly. One major disadvantage, however, is that OpenFOAM has a rather steep learning curve and although there are many resources available online, it is difficult to find short introductory courses. A tutorial was developed to provide a brief introduction to OpenFOAM and allow the students to perform simple simulations. Upon completing the tutorial, the students can build their own simulations. The tutorial covers geometry, mesh, boundary and initial conditions, solvers, schemes, post processing, and some additional features, such as shell scripts and parallel processing. A large portion of the tutorial is devoted to the geometry and mesh generation as this is one of the more challenging aspects of OpenFOAM compared to conventional graphical user interface CFD packages. Nevertheless, the students are exposed to the importance of properly setting the other simulation parameters through simple examples — e.g., comparing 2D channel flow simulations using potential flow and using turbulence modeling. One crucial aspect of the tutorial is that students are encouraged to experiment with deliberate modifications of the simulations to experience and understand how some of them do not provide reasonable results. Although the tutorial is rather brief and does not cover the topics in much detail, it aims to familiarize students with the basics of OpenFOAM, so that they can better understand other relevant resources. The OpenFOAM tutorial offers an alternative introduction to CFD compared to commercial CFD packages, which may not be readily available. The tutorial has already been utilized for three consecutive years at the University of New Hampshire, mostly by undergraduate students who worked/are working on senior projects involving CFD. The feedback has been generally positive.

scholarly journals Forecasting the cost of the means of measuring

2018 ◽  
Vol 28 (4) ◽  
pp. 76-84
Author(s):  
R. S. Anosov ◽  
D. M. Byvshikh ◽  
S. G. Zelenskaya
Keyword(s):  
Optimal Solution ◽  
Electronic Equipment ◽  
Measuring Instruments ◽  
Mathematical Methods ◽  
High Frequency Signal ◽  
Electronic Measuring ◽  
Urgent Task ◽  
Forecast Models ◽  
Multiplicative Models ◽  
The Cost

The cost of electronic measuring instruments is influenced by their technical characteristics and design factors. Moreover, this influence is often complex non-linear in nature, which greatly complicates the construction of an adequate cost forecast. When justifying the composition of complex measuring systems, the error can be significant and lead to a non- optimal solution. Therefore, improving the quality of forecasts of measuring instruments cost, that are part of the system for testing special-purpose electronic equipment is an urgent task, which is considered in the presented article. When considering the main approaches to forecasting measuring instruments cost, the apparatus of economic and mathematical methods is applied: mathematical statistics, qualitative analysis of the main characteristics and factors determining the measuring instruments cost, comparative analysis of the technical level of radio-electronic equipment samples, and the analog method. As an example, additive and multiplicative models are considered for practical calculations of the cost of high-frequency signal generators and spectrum analyzers as a function of the technical characteristics of these devices. Corrective functions have been identified, the use of which significantly improves the accuracy of forecast, which proves the feasibility of using such functions in forecast models of the measuring equipment cost.

scholarly journals To the issue of assessing the efficiency of distributed generation in low-voltage electric networks

2020 ◽  
Vol 178 ◽  
pp. 01077
Author(s):  
A.N. Alyunov ◽  
A.Yu Belyanin ◽  
A.E. Nemirovsky ◽  
D.A. Zaripova
Keyword(s):  
Power System ◽  
Distributed Generation ◽  
Power Supply ◽  
Low Voltage ◽  
Electric Networks ◽  
Cost Of Electricity ◽  
Industrial Enterprises ◽  
Urgent Task ◽  
The Cost ◽  
Supply Systems

This article considers an urgent task of using autonomous sources for power supply systems of industrial enterprises of small and medium-sized production. The efficiency of choosing the time of their switching-on in peak hours of power system in order to reduce the cost of electricity is shown on the example of diesel generators.

scholarly journals DESIGNING OF METHODS FOR OPTIMIZING THE RESTORATION OF BRIDGES

2020 ◽  
pp. 140-149
Author(s):  
A.I. Meneylyuk ◽  
◽  
S.V. Putilin ◽  
Keyword(s):  
Numerical Experiment ◽  
Performance Indicators ◽  
Multicriteria Analysis ◽  
Working Time ◽  
Factor Space ◽  
Factors Affecting ◽  
Experimental Planning ◽  
Urgent Task ◽  
The Cost ◽  
Factors Affecting Performance

Abstract. The biggest part of the bridges in Ukraine requires serious restoration works. However, in the literature sources there are no recommendations for choosing effective organizational and technological solutions for the reconstruction of bridges and overpasses. Therefore, the design of methods for optimizing bridge restoration is an urgent task. The working optimization hypothesis is formulated in the article. A general research technique is developed. The algorithm of multicriteria analysis is presented to determine the most effective structural and technological solutions for the restoration of the main structural elements of the studied structures. As a result of the analysis, the most significant indicators of restoration efficiency were determined. These were the cost of restoration of m2 of the bridge and the duration of restoration of the bridge. As factors affecting performance indicators ‒ the intensity of the use of working time and the combination of construction processes, the size of the roadway and the operational condition of the bridge were selected. The planning of the experiment is based on the well-known theory of experimental planning. A 25-point D-optimal plan was selected, which will provide adequate results with significantly fewer experiments than in a full-factor experiment. For calculations is used the program software COMPEX, which is developed at the Odessa State Academy of Civil Engineering and Architecture under the direction of Professor V. Voznesensky. Modelling allows to find the dependencies between the input (intensity use of working time, combination of construction processes, size of the carriageway of the bridge, operational condition of the bridge) and output (cost of restoration of m2 of the bridge, duration of restoration of the bridge) parameters. Dependences data is described with usage of second-degree polynomials obtained by processing the results of a numerical experiment. These dependencies will allow to determine the cost and duration of the restoration of the bridge for varying degrees of damage and the size of the bridge. In addition, to change indicators by choosing the optimal production modes (combination of processes, the intensity of the use of working time). The analysis of the results of a numerical experiment will allow us to assess the influence of organizational and technological factors on the performance indicators of restoration technologies and find areas of factor space that provide optimization of organizational and technological solutions for the restoration of damaged bridges. At the last stage of the numerical experiment, limits are introduced into graphic models (by cost, duration, combination, etc.) and the optimal organizational and technological solutions are determined taking into account the introduced restrictions.

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