scholarly journals Oscillation and Extinction Scenarios in the New Continuous Model of the Eruptive Phase of Alien Species Invasion

2019 ◽  
pp. 54-70
Author(s):  
Andrey Perevaryukha
Keyword(s):  
Computational Experiment ◽  
Insect Pests ◽  
Transition Process ◽  
Continuous Model ◽  
Relaxation Cycle ◽  
Deviating Argument ◽  
Alien Species Invasion ◽  
The Given ◽  
Delayed Phase ◽  
Biotic Environment

The paper considers the issue of modeling the development of those special population processes that include the passage of the eruptive phase of dynamics. Such brief hurricane regimes of change are often associated with the consequences of invasions of undesirable species. Processes in the introduction of a species can often develop through the delayed phase of a rapid increase in its abundance. The completion of the phase depends on many factors. Outbreaks of many species exert such a strong pressure on the environment that achieving a non-zero balance equilibrium is problematic. Such phenomena are interpreted by us as an extreme transition process to an uncertain state of the biotic environment before the beginning of the process. Depending on the counteraction, which is clearly seen in the examples of the dynamics of insect pests, simulated scenarios of similar phenomena can develop in various ways, including destruction of the habitat. The new model based on the equation with a deviating argument describes the variant of developing the repeated flash of catastrophic character. The scenario is implemented when non-harmonic cycle N*(rτ, t) occurs, which can not be orbitally stable under the given conditions, but becomes transitive. The cycle ends with the trivial-zero value. The scenario of the most abrupt form of the eruptive phase that we simulate ends in a computational experiment by the death of the invasive population, but without forming an unbounded trajectory from the oscillations, as was the case with the destruction of the relaxation cycle of the extreme amplitude in the population flash equation in our previous work.

scholarly journals Determination of the Optimal Values of the Parameters of the PI Controller by Minimum Integral Quadratic Criterion Taking Into Account the Values Transient Damping Coefficient

2021 ◽  
pp. 75-97
Author(s):  
Badri Gvasalia ◽  
Keyword(s):  
Random Search ◽  
Mathematical Problem ◽  
Transition Process ◽  
Visual Programming ◽  
Pi Controller ◽  
Programming System ◽  
Quadratic Integral ◽  
The Given ◽  
Visual Basic For Application

The problem of determining the optimal the values of the parameters of the PI controller by the quadratic integral criterion taking into account the coefficient of attenuation of the transition process. The problem is presented as a nonlinear mathematical problem programming. Finding the global minimum of the objective function carried out by random search, and to determine the parameters of the PI controller used the expanded amplitude-phase frequency response of the system. An attempt is made to provide designers with an effective tool for solving the above problem. The given graphs and tables facilitate the selection of parameters. To compile a computer program, the visual programming system VBA (Visual Basic for Application) is used. Concrete examples are given.

scholarly journals Processing and visualization of the results of parametric numerical calculations

2021 ◽  
Vol 2127 (1) ◽  
pp. 012025
Author(s):  
A E Bondarev ◽  
A E Kuvshinnikov
Keyword(s):  
Mathematical Modeling ◽  
Visual Analytics ◽  
Gas Dynamics ◽  
Computational Experiment ◽  
Visual Presentation ◽  
Key Factors ◽  
Multidimensional Arrays ◽  
Parametric Studies ◽  
The Given ◽  
Computational Technology

Abstract In modern problems of mathematical modeling in computational gas dynamics, it is increasingly necessary to implement parametric studies. In these cases, the key factors of the problem under consideration vary with the chosen step within the given ranges. Calculations of this kind can be effectively carried out by constructing a generalized computational experiment. A generalized computational experiment is a computational technology that combines the solution of mathematical modeling problems, parallel technologies, and visual analytics technologies. The results of a generalized computational experiment are multidimensional arrays, where the dimension of the arrays corresponds to the number of key factors. Processing and visual presentation of such arrays requires solving a number of separate tasks. The processing and visual presentation of the results are carried out for target functionals represented as a function of many variables. The report presents an examples of solving specific processing and visualization problems based on the implemented generalized computational experiment for 3D cone in supersonic flow.

scholarly journals Infectious and parasitic diseases of phytophagous insect pests in the context of extreme environmental conditions

2021 ◽  
Vol 67 (2) ◽  
pp. 72-84
Author(s):  
Danail Takov ◽  
Daniela Pilarska ◽  
Andreas Linde ◽  
Marek Barta
Keyword(s):  
Insect Pests ◽  
Insect Pest ◽  
Parasitic Diseases ◽  
Control Mechanisms ◽  
Phytophagous Insect ◽  
Abiotic Environment ◽  
Micro Level ◽  
A Chain ◽  
The Individual ◽  
Biotic Environment

Abstract The density of phytophagous insect pest populations is related (directly and indirectly) to several groups of factors that can be broadly divided into: abiotic, biotic and anthropogenic. Each extreme in the abiotic environment at a macro-level leads to a series of consecutive extremes in the biotic environment, which eventually results in micro-level responses in the individual organisms. The manifestation of factors acts in aggregate or in a sequence, creating a chain of processes around us. Insects very efficiently use the abundance of nutritional resources, resulting in a tremendous increase in their population density, and triggering control mechanisms through the emergence of parasitic and pathogenic infections (viruses, bacteria, fungi, microsporidia, protozoa and nematodes). The development of entomopathogenic infections in host populations is directly dependent on the characteristics of both the antagonist and the insect. It is associated with the lifestyle and life cycle of the insect, with features encoded in the mechanism of pathogen action, and limited by the pathogen’s virulence and pathogenicity.

scholarly journals Continuous- discrete mathematical model for control of growth of a plant population in a given time period under a given budget

2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Dilip Kumar Bhattacharya
Keyword(s):  
Discrete Model ◽  
Continuous Model ◽  
Plant Population ◽  
Logistic Growth ◽  
Initial Population ◽  
Growth Equation ◽  
Time Period ◽  
Net Profit ◽  
Discrete Mathematical Model ◽  
The Given

The paper discusses an economically viable way of controlling biomass of a vegetable plant population under the use of fertilizer in a given span of time under a given budget of expenditure. The span of time is divided in some suitable consecutive periods of equal duration P, called cohorts. The treatment is done on the available population of plant at the beginning of each cohort for a suitable time; the continuous dynamics in the change of biomass for this time period is governed by an ordinary differential equation involving total effort exerted in treating the initial population. Taking this improved value at the end of the time period as the initial value, the biomass of the population is allowed to move under its normal continuous dynamics given by Logistic growth equation for the rest of the time of that cohort.  The final concentration of the biomass at the end of the first cohort is obtained by following the above two types of dynamics. This is also considered as the starting biomass for the next cohort. The same process adopted for the first cohort is repeated for calculating the improvement of the biomass in the second cohort and the whole process is repeated till the end of the final cohort is reached. Next an objective function is formed for the given span of time. This measures the net profit in getting improvement in the weight of the biomass less the cost involved in the process of improving the weight of the biomass for the given period of time. As the analysis is done in considering different cohorts at regular intervals of time, so it is a discrete model. As within each cohort, the dynamics takes place continuously, so it is a continuous model too. As a whole, the model is found to be a continuous- discrete model. Hence method of optimal control for continuous-discrete model is used to determine how the treatment at the starting of each cohort be adjusted, depending on the allocated budget, so that the total net profit is maximum.

Application of Niyama criterion for predicting of shrinkage porosity of shaped castings

2021 ◽  
pp. 531-536
Author(s):  
E.S. Ivanina ◽  
V.P. Monastyrsky
Keyword(s):  
Technological Process ◽  
Computational Experiment ◽  
Critical Value ◽  
Shrinkage Porosity ◽  
Critical Values ◽  
Niyama Criterion ◽  
Cooling Conditions ◽  
The Given

Method for determining of the critical value of the Niyama criterion based on computational experiment is developed. It is found that the critical value of the Niyama criterion depends on the alloy cooling conditions and therefore is applicable only to the given technological process. The critical values of the Niyama criterion for casting s made of ML10 and 14Kh17N2L alloys obtained in permanent metal moulds and in moulds of coldhardening mixtures are determined. The obtained results are confirmed on shaped casting.

Insect juvenile hormones and their bioanalogues

1989 ◽  
Vol 54 (9) ◽  
pp. 2302-2329 ◽  
Author(s):  
Zdeněk Wimmer ◽  
Miroslav Romaňuk
Keyword(s):  
Aromatic Ring ◽  
Insect Pests ◽  
Biological Properties ◽  
Optically Active ◽  
Insect Development ◽  
Recent Information ◽  
Structural Types ◽  
Juvenile Hormones ◽  
Present Trend ◽  
The Given

This survey supplements and up-dates review articles of other authors published in the field of substances affecting the development of the insect, juvenoids. Attention has been paid primarily to such structures as deserved more detailed investigation in the given field owing to their biological properties, further to less known structures and facts, and lastly to the most recent information from literature, mainly paying attention to the present trend in searching for structural types of substances affecting insect development. The synthetic juvenoids discussed are divided into chapters, on the basis of the skeleton of the molecule, on aliphatic juvenoids, juvenoids with one aromatic ring in the molecule and finally juvenoids with two and more cycles (aromatic as well as non-aromatic) in the molecule. Certain attention has also been paid to optically active juvenoids. Finally the role is mentioned of complex hormonogen compounds, juvenogens, in the protection of cultured plants against economically important insect pests.

scholarly journals Periodic Solutions of Duffing Equation with an Asymmetric Nonlinearity and a Deviating Argument

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Zaihong Wang ◽  
Jin Li ◽  
Tiantian Ma
Keyword(s):  
Differential Equation ◽  
Periodic Solutions ◽  
Order Differential Equation ◽  
Sufficient Conditions ◽  
Second Order ◽  
Duffing Equation ◽  
Deviating Argument ◽  
Second Order Differential Equation ◽  
Existence Of Periodic Solutions ◽  
The Given

We study the existence of periodic solutions of the second-order differential equationx′′+ax+-bx-+g(x(t-τ))=p(t), wherea,bare two constants satisfying1/a+1/b=2/n,n∈N,τis a constant satisfying0≤τ<2π,g,p:R→Rare continuous, andpis2π-periodic. When the limitslimx→±∞g(x)=g(±∞)exist and are finite, we give some sufficient conditions for the existence of2π-periodic solutions of the given equation.

scholarly journals Stability of synchronous modes of the system of two connected self-oscillators

2021 ◽  
Vol 2140 (1) ◽  
pp. 012021
Author(s):  
S S Novikov ◽  
V S Kosterova
Keyword(s):  
Computational Experiment ◽  
Dynamic Instability ◽  
Initial Conditions ◽  
Resonant Coupling ◽  
Resonance Properties ◽  
The Given

Abstract In this paper investigate the dynamic instability of a system of two self-oscillators with a strong resonant coupling. The analysis of influence of resonance properties of coupling on stability of synchronous modes was carried out. In the course of the computational experiment, it was possible to observe the different behavior of the system depending on the given initial conditions. The boundaries of destruction of coherent modes are determined.

Anchorfibers and the Topography of Junctional SR

1977 ◽  
Vol 35 ◽  
pp. 582-583
Author(s):  
James Junker ◽  
Joachim R. Sommer
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Single Filament ◽  
Relaxation Cycle ◽  
10 Nm Filaments ◽  
Junctional Sarcoplasmic Reticulum

Junctional sarcoplasmic reticulum (JSR) in all its forms (extended JSR, JSR of couplings, corbular SR) in both skeletal and cardiac muscle is always located at the Z - I regions of the sarcomeres. The Z tubule is a tubule of the free SR (non-specialized SR) which is consistently located at the Z lines in cardiac muscle (1). Short connections between JSR and Z lines have been described (2), and bundles of filaments at Z lines have been seen in skeletal (3) and cardiac (4) muscle. In opossum cardiac muscle, we have seen bundles of 10 nm filaments stretching across interfibrillary spaces and adjacent myofibrils with extensions to the plasma- lemma in longitudinal (Fig. 1) and transverse (Fig. 2) sections. Only an occasional single filament is seen elsewhere along a sarcomere. We propose that these filaments represent anchor fibers that maintain the observed invariant topography of the free SR and JSR throughout the contraction-relaxation cycle.

Personal Problem Solving of Partners in Divorce Proceedings

2015 ◽  
Vol 36 (1) ◽  
pp. 82-103 ◽  
Author(s):  
Tereza Soukupova ◽  
Petr Goldmann
Keyword(s):  
Gender Differences ◽  
Problem Solving ◽  
Thematic Apperception Test ◽  
Scoring Systems ◽  
Personal Control ◽  
Personality Characteristics ◽  
Personal Problem ◽  
Thematic Apperception ◽  
And Gender ◽  
The Given

Abstract. The Thematic Apperception Test is one of the most frequently administered apperceptive techniques. Formal scoring systems are helpful in evaluating story responses. TAT stories, made by 20 males and 20 females in the situation of legal divorce proceedings, were coded for detection and comparison of their personal problem solving ability. The evaluating instrument utilized was the Personal Problem Solving System-Revised (PPSS-R) as developed by G. F. Ronan. The results indicate that in relation to card 1, men more often than women saw the cause of the problem as removable. With card 6GF, women were more motivated to resolve the given problem than were men, women had a higher personal control and their stories contained more optimism compared to men’s stories. In relation to card 6BM women, more often than men, used emotions generated from the problem to orient themselves within the problem. With card 13MF, the men’s level of stress was less compared to that of the women, and men were more able to plan within the context of problem-solving. Significant differences in the examined groups were found in those cards which depicted significant gender and parental potentials. The TAT can be used to help identify personality characteristics and gender differences.

Sign in / Sign up

Export Citation Format

Share Document