scholarly journals Comportement asymptotique d’un modèle à commutation de la prolifération du Typha

2012 ◽  
Vol Volume 15, 2012 ◽  
Author(s):  
Mamadou Lamine Diagne ◽  
Papa Ibrahima Ndiaye ◽  
Mary Teuw Niane ◽  
Tewfik Sari
Keyword(s):  
Nonlinear Dynamics ◽  
Mathematical Model ◽  
Theoretical Study ◽  
Plant Population ◽  
Equilibrium Solutions ◽  
Key Factors ◽  
Comportement Asymptotique ◽  
International Audience

International audience In this paper we propose a mathematical model of the Typha growth and analyse its stability. The model that we plan to study describes the dynamics of the plant population. The theoretical study of this model determines the key factors of the Typha proliferation. We present the analysis of equilibrium solutions and lead a study of their local stability.This constitutes a first step towards a more detailed study of the nonlinear dynamics of this model.

scholarly journals Limited Dispersal, Deleterious Mutations and the Evolution of Sex

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 1053-1060
Author(s):  
Joel R Peck
Keyword(s):  
Mathematical Model ◽  
Sexual Reproduction ◽  
Genetic Locus ◽  
Genetic Material ◽  
Plant Population ◽  
Deleterious Mutations ◽  
Animal Populations ◽  
Offspring Sex ◽  
Limited Dispersal ◽  
Hermaphroditic Plant

Abstract This study presents a mathematical model that allows for some offspring to be dispersed at random, while others stay close to their mothers. A single genetic locus is assumed to control fertility, and this locus is subject to the occurrence of deleterious mutations. It is shown that, at equilibrium, the frequency of deleterious mutations in the population is inversely related to the rate of dispersal. This is because dispersal of offspring leads to enhanced competition among adults. The results also show that sexual reproduction can lead to a decrease in the equilibrium frequency of deleterious mutations. The reason for this relationship is that sex involves the dispersal of genetic material, and thus, like the dispersal of offspring, sex enhances competition among adults. The model is described using the example of a hermaphroditic plant population. However, the results should apply to animal populations as well.

Marketing Fraud: An Approach for Differentiating Multilevel Marketing from Pyramid Schemes

2002 ◽  
Vol 21 (1) ◽  
pp. 139-151 ◽  
Author(s):  
Peter J. Vander Nat ◽  
William W. Keep
Keyword(s):  
Mathematical Model ◽  
Distribution Channel ◽  
Specific Form ◽  
The Internet ◽  
Key Factors ◽  
Direct Selling ◽  
Multilevel Marketing ◽  
International Growth ◽  
Pyramid Scheme ◽  
Pyramid Schemes

A specific form of direct selling, multilevel marketing (MLM), experienced significant international growth during the 1990s, facilitated in part by the development of the Internet. A corresponding increase in the investigation and prosecution of illegal pyramid schemes occurred during the same period. These parallel activities led to increased uncertainty among marketing managers who used or wished to use the MLM approach. The authors examine similarities between the multilevel approach to marketing and activities associated with illegal pyramid schemes. A mathematical model is used to differentiate between the two on the basis of previous pyramid scheme cases and current U.S. law. The results of the model suggest key factors that marketers interested in MLM will need to consider when developing this type of distribution channel.

Robotic chemotherapy compounding: A multicenter productivity approach

2021 ◽  
pp. 107815522199284
Author(s):  
Ana C Riestra ◽  
Carmen López-Cabezas ◽  
Marion Jobard ◽  
Mertxe Campo ◽  
María J Tamés ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Correlation Analysis ◽  
Hospital Pharmacy ◽  
Multiple Regression Model ◽  
Key Factors ◽  
Independent Variables ◽  
Specific Factors ◽  
Automated Process ◽  
Productivity Indicators ◽  
The Mathematical Model

Introduction The aim of this study is to compare productivity of the KIRO Oncology compounding robot in three hospital pharmacy departments and identify the key factors to predict and optimize automatic compounding time. Methods The study was conducted in three hospitals. Each hospital compounding workload and workflow were analyzed. Data from the robotic compounding cycles from August 2017 to July 2018 were retrospectively obtained. Nine cycle specific parameters and five productivity indicators were analysed in each site. One-to-one differences between hospitals were evaluated. Next, a correlation analysis between cycle specific factors and productivity indicators was conducted; the factors presenting a highest correlation to automatic compounding time were used to develop a multiple regression model (afterwards validated) to predict the automatic compounding time. Results A total of 2795 cycles (16367 preparations) were analysed. Automatic compounding time showed a relevant positive correlation (ǀrs|>0.40) with the number of preparations, number of vials and total volume per cycle. Therefore, these cycle specific parameters were chosen as independent variables for the mathematical model. Considering cycles lasting 40 minutes or less, predictability of the model was high for all three hospitals (R2:0.81; 0.79; 0.72). Conclusion Workflow differences have a remarkable incidence in the global productivity of the automated process. Total volume dosed for all preparations in a cycle is one of the variables with greater influence in automatic compounding time. Algorithms to predict automatic compounding time can be useful to help users in order to plan the cycles launched in KIRO Oncology.

KEY FACTORS FOR REDUCING LIVE POULTRY LOSSES DURING TRANSPORTATION

2021 ◽  
Vol 113 ◽  
pp. 115-131
Author(s):  
Valery KURGANOV ◽  
Mikhail GRYAZNOV ◽  
Egor TIMOFEEV ◽  
Liliya POLYAKOVA
Keyword(s):  
Mathematical Model ◽  
Factor Analysis ◽  
Economic Impact ◽  
Processing Plant ◽  
Poultry Farm ◽  
Key Factors ◽  
Live Poultry

The results of this study on the loss of live poultry at various stages of delivery from the farm to the processing plant by road are given. A factor analysis of the reasons for the loss of livestock delivered from the farm to the processing plant was carried out. The dependencies of livestock losses on loading delays and the duration of the movement of the loaded poultry farm to the processing plant were established. Methodological recommendations for rationing the number of injuries observed during delivery were developed. The study of losses of live birds during delivery to the processing plant from the density of stocking in shipping boxes was carried out; the economic and mathematical model for optimizing the landing of live birds in shipping boxes was proposed. The calculation of the economic impact of the implementation of the results of the study is given.

Enhancement the Solar Still Performance Using Chimney Exhaust Gases

2021 ◽  
Author(s):  
Hamdy Hassan
Keyword(s):  
Mathematical Model ◽  
Theoretical Study ◽  
Saline Water ◽  
Kutta Method ◽  
Solar Still ◽  
Climate Conditions ◽  
Exhaust Gases ◽  
Runge Kutta Method ◽  
The Impact ◽  
The Mathematical Model

Abstract In this paper, a theoretical study is presented on enhancement of the solar still performance by using the exhaust gases passing inside a chimney under the still basin. The impact of the exhaust gases temperature on the solar still temperature, productivity, and efficiency are considered. The performance of solar still with chimney is compared with that of conventional solar still. The study is carried out under the hot and climate conditions of Upper Egypt. A complete transient mathematical model of the physical model including the solar still regions temperatures, productivity, and heat transfer between the solar still and the exhaust gases are constructed. The mathematical model is solved numerically by using fourth-order Runge-Kutta method and is programmed by using MATLAB. The mathematical model is validated using an experimental work. The results show that the solar still saline water temperature increases and productivity with using and rising the exhaust gases. Furthermore, the impact of using exhaust gases on the still performance in winter is greater than in summer. using chimney exhaust gases at 75 °C and 125 °C enhances the daily freshwater yield of the conventional still by more than three times and about six times in winter, respectively, and about two and half times and more than three times in summer, respectively.

Nonlinear Dynamics of the Bombardier Beetle

1999 ◽  
Author(s):  
Richard H. Rand ◽  
Erika T. Wirkus ◽  
J. Robert Cooke
Keyword(s):  
Nonlinear Dynamics ◽  
Mathematical Model ◽  
Differential Equations ◽  
Equilibrium Point ◽  
Defense Mechanism ◽  
Fluid Pressure ◽  
Pulsed Jet ◽  
Dependent Variables

Abstract This work investigates the dynamics by which the bombardier beetle releases a pulsed jet of fluid as a defense mechanism. A mathematical model is proposed which takes the form of a pair of piece wise continuous differential equations with dependent variables as fluid pressure and quantity of reactant. The model is shown to exhibit an effective equilibrium point (EEP). Conditions for the existence, classification and stability of an EEP are derived and these are applied to the model of the bombardier beetle.

Coupling Effects on Synchronizability of Two-Layer Network's Projective Outer Synchronization

2017 ◽  
Vol 873 ◽  
pp. 353-357
Author(s):  
Bo Yu Feng ◽  
Zhi Hao Zhang
Keyword(s):  
Nonlinear Dynamics ◽  
Mathematical Model ◽  
Complex Network ◽  
Simulation Experiment ◽  
Small World ◽  
Experimental Results ◽  
Coupling Effects ◽  
Network Synchronization ◽  
Numerical Examples ◽  
Outer Synchronization

Based on nonlinear dynamics theory and knowledge of complex network, this paper expanded the range of two-layer network synchronization to projective outers synchronization. A mathematical model was constructed and feasibility of synchronization was demonstrated. Then we improved the model in order to study the function of different couplings [1]. Numerical examples are examined to compare the synchronizability of projective outer synchronization with different couplings. A rule called "outer small-world effect" was found due to simulation experiment. Finally, some instances were used to explain experimental results.

An Efficient Approach to Define the Input Stimuli to Suppress Epileptic Seizures Described by the Epileptor Model

2020 ◽  
Vol 30 (11) ◽  
pp. 2050062
Author(s):  
João Angelo Ferres Brogin ◽  
Jean Faber ◽  
Douglas Domingues Bueno
Keyword(s):  
Nonlinear Dynamics ◽  
Mathematical Model ◽  
Exact Solution ◽  
Feedback Control ◽  
Epileptic Seizures ◽  
Neural Dynamics ◽  
Practical Application ◽  
Control Gain ◽  
The World ◽  
The Mathematical Model

Epilepsy affects about 70 million people in the world. Every year, approximately 2.4 million people are diagnosed with epilepsy, two-thirds of them will not know the etiology of their disease, and 1% of these individuals will decease as a consequence of it. Due to the inherent complexity of predicting and explaining it, the mathematical model Epileptor was recently developed to reproduce seizure-like events, also providing insights to improve the understanding of the neural dynamics in the interictal and ictal periods, although the physics behind each parameter and variable of the model is not fully established in the literature. This paper introduces an approach to design a feedback-based controller for suppressing epileptic seizures described by Epileptor. Our work establishes how the nonlinear dynamics of this disorder can be written in terms of a combination of linear sub-models employing an exact solution. Additionally, we show how a feedback control gain can be computed to suppress seizures, as well as how specific shapes applied as input stimuli for this purpose can be obtained. The practical application of the approach is discussed and the results show that the proposed technique is promising for developing controllers in this field.

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