scholarly journals Data Analysis of Physical Fitness Monitoring Based on Mathematical Models

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Cuixiang Guo ◽  
Junwu Suo ◽  
Chunguang Xu ◽  
Xinhua Yang ◽  
Liping Zhang
Keyword(s):  
College Students ◽  
Physical Fitness ◽  
Mathematical Models ◽  
Equilibrium Point ◽  
Quantitative Research ◽  
Equation System ◽  
Differential Equation System ◽  
Main Work ◽  
Existence And Stability

Physical monitoring and analysis are of great significance to improve national physical fitness. The main work of this paper is that the physical health level of college students is studied and analysed by using a statistical model and mathematical model. According to the characteristics of the collected data, different mathematical models are established. Firstly, the grey correlation model is used to analyse the correlation between pull-up and other physical fitness indexes. Then, based on the classification of college students and the influence and flow law of interclass crowd, a differential equation system is established based on the LMC model. By analysing the existence and stability of the equilibrium point of the system, as well as the possible folding bifurcation and backward bifurcation at the equilibrium point, this paper makes qualitative and quantitative research on the trend of college students’ physical exercise on campus.

scholarly journals Stability of Non-Hyperbolic Equilibrium Point for Polynomial System of Differential Equations

TEM Journal ◽  
2021 ◽  
pp. 1418-1422
Author(s):  
Vahidin Hadžiabdić ◽  
Midhat Mehuljić ◽  
Jasmin Bektešević
Keyword(s):  
Differential Equations ◽  
Equilibrium Point ◽  
Normal Forms ◽  
Polynomial System ◽  
Equation System ◽  
Differential Equation System ◽  
Nonlinear Part ◽  
The Stability ◽  
Hyperbolic Equilibrium ◽  
Hyperbolic Equilibrium Point

In this paper, a polynomial system of plane differential equations is observed. The stability of the non-hyperbolic equilibrium point was analyzed using normal forms. The nonlinear part of the differential equation system is simplified to the maximum. Two nonlinear transformations were used to simplify first the quadratic and then the cubic part of the system of equations.

“Spending all this time stressing and worrying and calculating”: Marginal Food Security and Student Life at a Diverse Urban University

2021 ◽  
pp. 1-19
Author(s):  
Ryan J Gamba ◽  
Michael T Schmeltz ◽  
Nancy Ortiz ◽  
Alina Engelman ◽  
Juleen Lam ◽  
...  
Keyword(s):  
College Students ◽  
Food Security ◽  
Quantitative Research ◽  
Academic Motivation ◽  
Physical Symptoms ◽  
Healthy Food ◽  
High Food ◽  
Structured Interviews ◽  
Future Health ◽  
Food Security Status

Abstract Objective: Food security status is a continuum ranging from high to very low food security. While marginal food security falls next to high food security on the spectrum, new quantitative research indicates marginal food security status is associated with negative health outcomes and poor academic performance among college students. Qualitative research focusing on college students experiencing marginal food security has not been conducted. This study aims to qualitatively explore experiences of college students with marginal food security and to identify themes to better understand and provide context regarding how marginal food security impacts students. Design: Students were recruited for semi-structured interviews with questions designed to study the challenges associated with students’ food situations. All interviews were recorded and transcribed with themes identified via an inductive approach. Setting: A large public university on the US west coast. Participants: Thirty college students. Results: Key themes that emerged: purchasing cheap unhealthy foods; insufficient time to prepare and eat meals on a regular basis; stress and anxiety around the inability to eat healthy food and future health issues; self-perception of health when eating poorly along with physical symptoms; and low academic motivation by not fully participating in their courses due to few healthy food options or missing meals. Conclusion: Marginal food security can potentially diminish students’ health and their capacity to learn and succeed in their coursework. The results emphasize that students experiencing marginal food security should not be grouped with students experiencing high food security.

scholarly journals A comprehensive review of sucker rod pumps’ components, diagnostics, mathematical models, and common failures and mitigations

2021 ◽  
Author(s):  
Sherif Fakher ◽  
Abdelaziz Khlaifat ◽  
M. Enamul Hossain ◽  
Hashim Nameer
Keyword(s):  
Mathematical Models ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Gas Industry ◽  
Holistic View ◽  
Comprehensive Review ◽  
Artificial Lift ◽  
Sucker Rod ◽  
Sucker Rod Pump

AbstractIn many oil reservoirs worldwide, the downhole pressure does not have the ability to lift the produced fluids to the surface. In order to produce these fluids, pumps are used to artificially lift the fluids; this method is referred to as artificial lift. More than seventy percent of all currently producing oil wells are being produced by artificial lift methods. One of the most applied artificial lift methods is sucker rod pump. Sucker rod pumps are considered a well-established technology in the oil and gas industry and thus are easy to apply, very common worldwide, and low in capital and operational costs. Many advancements in technology have been applied to improve sucker rod pumps performance, applicability range, and diagnostics. With these advancements, it is important to be able to constantly provide an updated review and guide to the utilization of the sucker rod pumps. This research provides an updated comprehensive review of sucker rod pumps components, diagnostics methods, mathematical models, and common failures experienced in the field and how to prevent and mitigate these failures. Based on the review conducted, a new classification of all the methods that can fall under the sucker rod pump technology based on newly introduced sucker rod pump methods in the industry has been introduced. Several field cases studies from wells worldwide are also discussed in this research to highlight some of the main features of sucker rod pumps. Finally, the advantages and limitations of sucker rod pumps are mentioned based on the updated review. The findings of this study can help increase the understanding of the different sucker rod pumps and provide a holistic view of the beam rod pump and its properties and modeling.

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