scholarly journals Modeling the deployment of a two-link spoke of a large-sized space reflector taking into account the backlash

2021 ◽  
Vol 5 (3) ◽  
pp. 146-152
Author(s):  
F. V. Mitin ◽  
E. N. Nikulin
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Field Tests ◽  
Launch Vehicle ◽  
Stabilization Time ◽  
Urgent Task ◽  
Dimensional Parameters ◽  
The Creation

This article discusses the process of deployment a two-link spoke of a large-sized transformable space-based reflector. In view of the high costs of carrying out field tests, the construction of correct mathematical models is an urgent task. Currently, the creation of large-sized systems is actively developing. Such systems consist of several interconnected links. When delivered to a given orbit, the large-sized system is folded for placement in the launch vehicle. After entering the orbit, it is deployed to the specified operating state. A mathematical model has been developed for the deployment of the spoke, improved in terms of taking into account the separation of parameters depending on the length and time, which makes it possible to study the arising vibrations of the structure. It is important to take into account the backlash in the connections. Even small gaps in the spoke link connections can lead to a manifold increase in the stabilization time of the system. The developed mathematical model makes it possible to consider various conditions for linking links, change the mass-dimensional parameters and materials of the spoke. The results of modeling are presented, showing the correctness of mathematical models. Conclusions are made about the admissibility of using mathematical models for spokes consisting of a larger number of links.

scholarly journals MODEL MATEMATIKA SEDERHANA REDAMAN GETARAN PADA SAYAP PESAWAT TERBANG

2016 ◽  
Vol 8 (1) ◽  
pp. 8
Author(s):  
Rukmono Budi Utomo
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Aircraft Engine ◽  
Aircraft Wing ◽  
Wing Vibration ◽  
The Creation

We have known that when the plane encountered turbulence or in a hard landing, the aircraft engine will swing to dampen vibrations of the aircraft wing. Thus, based on rights, this research is investigating and constructing mathematical model of aircraft wing vibration. In this research, we described not only the creation of mathematical models, but also the analysis of the model and its interpretation.

scholarly journals The Heat Exchange Mathematical Model of Fire in Cable Tunnel Adequacy Research

2018 ◽  
Vol 7 (4.3) ◽  
pp. 303 ◽  
Author(s):  
Oleksandr Nuianzin ◽  
Taras Samchenko ◽  
Serhii Kasiarum ◽  
Kostiantyn Hryhorenko ◽  
Mykola Kryshtal
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Computational Experiment ◽  
Field Tests ◽  
Test Site ◽  
Software Systems ◽  
Geometrical Parameters ◽  
Heat And Mass Exchange ◽  
Student’S T ◽  
Full Scale Tests

According to the results of the conducted studies, the adequacy of the mathematical models of cable tunnels for their further use in the study of the temperature regime of the fire was checked. For this purpose, full–scale tests and findings about the dynamics of temperature change in cable tunnels with known geometrical parameters and fire load were conducted at the experimental test site of the Ukrainian Civil Protection Research Institute (Kyiv).In one of the CFD software systems, a mathematical model of a cable tunnel similar to the actual one was created. A computational experiment was conducted. Based on the results of the computational experiment and field tests, the criteria for adequacy (Student's t–criterion, Cochran's Q–criterion, Fisher's F–criterion) and the relative error of the experiments were calculated. On the basis of the analysis, the adequacy of the used mathematical models was studied.In this article, further development of the use of computational experiments to study the heat and mass exchange processes during fires in cable tunnels.  

scholarly journals COMPUTER SIMULATION AND ANALYTICAL SOLUTION OF FOUR BAR MECHANISM

2020 ◽  
pp. 120-128
Author(s):  
Darina Hroncová
Keyword(s):  
Mathematical Model ◽  
Analytical Solution ◽  
Mathematical Models ◽  
Computer Model ◽  
Analytical Methods ◽  
Kinematic Analysis ◽  
Linkage Mechanism ◽  
The Creation ◽  
Four Bar Linkage ◽  
The Mathematical Model

Urgency of the research. The use of computers in technical practice leads to the extension of the possibility of solving mathematical models. This makes it possible to gradually automate complex calculations of equations of mathematical models. It is necessary to input the relevant inputs of the mathematical model, to build a simulation computer model and to monitor and evaluate the output results using a computer's output device. Target setting. The possibilities of modeling a four-bar linkage mechanism by classical analytical methods and methodsusing computer modeling are presented in this paper.The problem is to describe the creation of a computer model and to show the mathematical model and its solution in the classical ways. Actual scientific researches and issues analysis. The inspiration for the creation of the article was the study of the mechanisms in the work [1-3] and the study of other resources available in library and journal materials, as well as prepared study materials for students of Technical university Kosice. Uninvestigated parts of general matters defining. The question of building a real mechanism model. The possibilities to building a real model, based on the result of simulation. The research objective. The aim of this paper is to develop a functional model of the mechanism in ADAMS/View and Matlab and its complete kinematic analysis.The statement of basic materials.The task was to create a computer model in MSC Adams and Matlab and to perform a four-bar linkage mechanism kinematic analysis. At the same time the classical procedure of analytical methods of kinematic analysis was described. Kinematic сharacteristics of driven members and their selected points were determined. The movement of the parts of the mechanism in its significant points was analyzed. The results of the solution were shown in both programs in graphical form. Kinematic analysis was performed by both vector and graphical methods. Finally, the results with a graphical representation of parameters such as angular displacement, angular velocity and angular acceleration of mechanism members are presented in this work. The results of these solutions are created in the form of graphs. To ensure that the results do not differ from the model real, a good computer model gradually was created by its verification and modification, which is one of the advantages of MSC Adams. The practical applicability of the mathematical model was limited by the existence of an analytical solution. Conclusions. The development of computer technology has expanded the limit of solvability of mathematical models and made it possible to gradually automate the calculation of equations of mathematical models. In a computer model the auto-mated calculation can be treated as a real object sample. In various variations of calculation, we can monitor and measure the behavior of an object under different conditions, under the influence of different inputs. Graphical and vector methods were used for classical analytical methods. MSC Adams and Matlab were used for the automated calculations.

scholarly journals Mathematical aspects of nutrition systems projecting for dietary therapy

2017 ◽  
Vol 11 (1) ◽  
Author(s):  
G. Krutovyi ◽  
A. Zaparenko ◽  
A. Borysova
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Calcium Deficiency ◽  
Dietary Therapy ◽  
The Creation ◽  
Prevention And Therapy ◽  
Content Optimization

The mathematical toolkit created and used for the design of durable nutrition systems aimed at the prevention and therapy of the diseases caused by calcium deficiency is analyzed. In particular, these are: the complex of mathematical models of the expendable diets and methods of the ingredients content optimization in them, mathematical model of daily diets optimization, and formalizationed method of fast and light determination of a diet’s biological value.The ways for the improvement of the developed mathematical toolkit aimed at the creation of the nutrition systems with higher level of both nutrients balance and provision of daily needs in them on the basis of using unconventional floury products enriched with the deficient nutrients, functionals for balancing the connected groups of nutrients are determined, as well as the introduction of aggregated restrictions on these groups of nutrients to the models (both products and rations).

A mathematical model and an algorithm for sampling sets of components on the Assembly enterprises of space technology

2018 ◽  
Vol 15 (1) ◽  
pp. 39-55
Author(s):  
V. B. Rudakov ◽  
V. M. Makarov ◽  
M. I. Makarov
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Space Technology ◽  
Economic Costs ◽  
Problem Statement ◽  
Optimal Plan ◽  
Product Mix ◽  
Technical Parameters ◽  
Complex Products ◽  
Assembly Plants

The article considers the problem of determining the rational plans of the input sampling reliability and technical parameters of components of space technology, the totality of which is supplied to the Assembly plants for the manufacture of complex products of space technology. Problem statement and mathematical model based on the minimization of the economic costs of control and losses related to the risks of taking wrong decisions, are given in the article. The properties of the mathematical models are investigated, the algorithm for its optimization is developed. The result is an optimal plan for the sampling of sets of components, which includes: an optimal product mix subject to mandatory control of the aggregate and optimum risks of first and second kind, when acceptance number of statistical plan is zero. The latter circumstance is due to the high requirements of reliability and technical parameters of products of space technology.

Rapid determination of glomerular filtration rate by single-bolus inulin: a comparison of estimation analyses

1998 ◽  
Vol 84 (6) ◽  
pp. 2154-2162 ◽  
Author(s):  
Cord Sturgeon ◽  
Albert D. Sam ◽  
William R. Law
Keyword(s):  
Mathematical Model ◽  
Glomerular Filtration Rate ◽  
Mathematical Models ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Rapid Determination ◽  
Constant Infusion ◽  
Sprague Dawley ◽  
Single Bolus ◽  
Sprague Dawley Rats

Rapid measurement of glomerular filtration rate (GFR) by an inulin single-bolus technique would be useful, but its accuracy has been questioned. We hypothesized that reported inaccuracies reflect the use of inappropriate mathematical models. GFR was measured in 14 intact and 5 unilaterally nephrectomized conscious male Sprague-Dawley rats (mean weight 368 ± 12 g) by both single-bolus (25 mg/kg) and constant-infusion techniques (0.693 mg ⋅ kg−1 ⋅ min−1). The temporal decline in plasma inulin concentration was analyzed through biexponential curve fitting, which accounted for renal inulin loss before complete vascular and interstitial mixing. We compared our mathematical model based on empirical rationale with those of other investigators whose studies suggest inaccuracy of single-bolus methods. Our mathematical model yielded GFR values by single bolus that agreed with those obtained by constant infusion [slope = 0.94 ± 0.16 (SE); y intercept = 0.23 ± 0.64; r = 0.82]. In comparison to the data obtained by constant inulin infusion, this method yielded a very small bias of −0.0041 ± 0.19 ml/min. Two previously reported models yielded unsatisfactory values (slope = 1.46 ± 0.34, y intercept = 0.47 ± 1.5, r = 0.72; and slope = 0.17 ± 1.26, y intercept = 17.15 ± 5.14, r = 0.03). The biases obtained by using these methods were −2.21 ± 0.42 and −13.90 ± 1.44 ml/min, respectively. The data indicate that when appropriate mathematical models are used, inulin clearance after single-bolus delivery can be used to measure GFR equivalent to that obtained by constant infusion of inulin. Attempts to use methods of analysis for simplicity or expediency can result in unacceptable measurements relative to the clinical range of values seen.

scholarly journals Determination of the Vertical Load on the Carrying Structure of a Flat Wagon with the 18–100 and Y25 Bogies

2021 ◽  
Vol 11 (9) ◽  
pp. 4130
Author(s):  
Oleksij Fomin ◽  
Alyona Lovska ◽  
Václav Píštěk ◽  
Pavel Kučera
Keyword(s):  
Mathematical Model ◽  
Fatigue Strength ◽  
Service Life ◽  
Dynamic Characteristics ◽  
Dynamic Load ◽  
Field Tests ◽  
Vertical Load ◽  
Mathcad Software ◽  
The Mathematical Model

The study deals with determination of the vertical load on the carrying structure of a flat wagon on the 18–100 and Y25 bogies using mathematic modelling. The study was made for an empty wagon passing over a joint irregularity. The authors calculated the carrying structure of a flat wagon with the designed parameters and the actual features recorded during field tests. The mathematical model was solved in MathCad software. The study found that application of the Y25 bogie for a flat wagon with the designed parameters can decrease the dynamic load by 41.1% in comparison to that with the 18–100 bogie. Therefore, application of the Y25 bogie under a flat wagon with the actual parameters allows decreasing the dynamic loading by 41.4% in comparison to that with the 18–100 bogie. The study also looks at the service life of the supporting structure of a flat wagon with the Y25 bogie, which can be more than twice as long as the 18–100 bogie. The research can be of interest for specialists concerned with improvements in the dynamic characteristics and the fatigue strength of freight cars, safe rail operation, freight security, and the results of the research can be used for development of innovative wagon structures.

Twin Models

1970 ◽  
Vol 19 (1-2) ◽  
pp. 141-141
Author(s):  
L. Gedda ◽  
G. Brenci ◽  
M. T. Lun
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Genetic Parameters ◽  
Simultaneous Recording ◽  
Theoretical Relationship ◽  
Twin Models

The theoretical relationship between the distribution of a given trait in a population of twin pairs and several genetic parameters has been examined. In particular, a series of mathematical models has been worked out, that, when applied to a twin population, nonselected for the occurrence of a given trait and nondiagnosed as to zygosity, leads to an estimate of:1) The MZ: DZ ratio in the population;2) The frequency of the genotype responsible for a given trait;3) The probability of manifestation of the trait;4) The value of epistatic factors.A further mathematical model affords the estimate of linkage in the hypothesis of simultaneous recording of more than one trait.

Numerical modelling of swirling momentumless turbulent wake dynamics

2018 ◽  
pp. 37-48
Author(s):  
Андрей Геннадьевич Деменков ◽  
Геннадий Георгиевич Черных
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Mathematical Models ◽  
Equations Of Motion ◽  
Turbulent Wake ◽  
The Body ◽  
Jet Flows ◽  
Reynolds Stresses ◽  
Bodies Of Revolution ◽  
Averaged Equations

С применением математической модели, включающей осредненные уравнения движения и дифференциальные уравнения переноса нормальных рейнольдсовых напряжений и скорости диссипации, выполнено численное моделирование эволюции безымпульсного закрученного турбулентного следа с ненулевым моментом количества движения за телом вращения. Получено, что начиная с расстояний порядка 1000 диаметров от тела течение становится автомодельным. На основе анализа результатов численных экспериментов построены упрощенные математические модели дальнего следа. Swirling turbulent jet flows are of interest in connection with the design and development of various energy and chemical-technological devices as well as both study of flow around bodies and solving problems of environmental hydrodynamics, etc. An interesting example of such a flow is a swirling turbulent wake behind bodies of revolution. Analysis of the known works on the numerical simulation of swirling turbulent wakes behind bodies of revolution indicates lack of knowledge on the dynamics of the momentumless swirling turbulent wake. A special case of the motion of a body with a propulsor whose thrust compensates the swirl is studied, but there is a nonzero integral swirl in the flow. In previous works with the participation of the authors, a numerical simulation of the initial stage of the evolution of a swirling momentumless turbulent wake based on a hierarchy of second-order mathematical models was performed. It is shown that a satisfactory agreement of the results of calculations with the available experimental data is possible only with the use of a mathematical model that includes the averaged equations of motion and differential equations for the transfer of normal Reynolds stresses along the rate of dissipation. In the present work, based on the above mentioned mathematical model, a numerical simulation of the evolution of a far momentumless swirling turbulent wake with a nonzero angular momentum behind the body of revolution is performed. It is shown that starting from distances of the order of 1000 diameters from the body the flow becomes self-similar. Based on the analysis of the results of numerical experiments, simplified mathematical models of the far wake are constructed. The authors dedicate this work to the blessed memory of Vladimir Alekseevich Kostomakha.

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