systems dynamics
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Author(s):  
Ferdianto Budi Samudra ◽  
Santun RP Sitorus ◽  
Edi Santosa ◽  
Machfud Machfud

History shows the long process of apple plants originating from subtropical regions adapting to Indonesia's tropical climate until its popularity is increasingly marginalized and replaced with other commodities, as evidenced by the decreasing land area, especially in Batu City. Indonesia. In developing and analyzing solutions based on the principles of sustainable development, an integrated and holistic approach is required.  To understand problems and find solutions, we can use Systems dynamics. The purpose of this study is to obtain a policy scenario that encourages sustainable apple farming. Data is collected from the local government and BPS City or Province so that the selected variables follow the specific location. The system approach is used to identify needs, problem formulation, preparation of input-output diagrams, cause-effect diagrams and stock-flow diagrams. A series of scenarios is created and tested through simulation to understand the system's dynamic behavior better and obtain the desired output. The best scenario was chosen, namely by replanting 10% of old plant each year, using integrated agriculture with 3 female and 1 male brooders, reduction of land change with 50% success, Local economic development by integrating tourist ticket and hotels with 0,75 kg apple fruits also increasing health support for students


2022 ◽  
Vol 73 ◽  
pp. 102712
Author(s):  
Brenda T. Poon ◽  
Chris Atchison ◽  
Amanda Kwan ◽  
Campbell Veasey

2022 ◽  
Vol 191 ◽  
pp. 107221
Author(s):  
Hoon C. Shin ◽  
Sechindra Vallury ◽  
Joshua K. Abbott ◽  
John M. Anderies ◽  
David J. Yu

Systems ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 88
Author(s):  
John M. Nevison ◽  
Karim J. Chichakly

A project model is presented that weaves together ideas from earned value project management and systems dynamics. It is able to adjust to increasingly unhealthy actual project behaviors in ways that preserve the signature pattern of the staffing histograms observed in the real world and provide a tool for managers to correct projects that are not meeting the plan. Starting from the planned staffing histogram and the project performance baseline, the model captures the delay and cost of experience dilution, includes the unplanned-for effort that is revealed in the typical pattern of the Cost Performance Index, assesses progress using the actual cost to date and the earned value to date, and adjusts staffing, scope, or both, to complete the project on schedule. A new method of approximating work remaining, called project-to-date, is shown to track the planned staffing histogram better than the commonly used fraction-complete method.


Fractals ◽  
2021 ◽  
Author(s):  
ZUBAIR AHMAD ◽  
FARHAD ALI ◽  
AISHA M. ALQAHTANI ◽  
NAVEED KHAN ◽  
ILYAS KHAN

Chemical processes are constantly occurring in all existing creatures, and most of them contain proteins that are enzymes and perform as catalysts. To understand the dynamics of such phenomena, mathematical modeling is a powerful tool of study. This study is carried out for the dynamics of cooperative phenomenon based on chemical kinetics. Observations indicate that fractional models are more practical to describe complex systems’ dynamics, such as recording the memory in partial and full domains of particular operations. Therefore, this model is modeled in terms of classical-order-coupled nonlinear ODEs. Then the classical model is generalized with two different fractional operators of Caputo and Atangana–Baleanu in a Caputo sense. Some fundamental theoretical analysis for both the fractional models is also made. Reaction speeds for the extreme cases of positive/negative and no cooperation are also calculated. The graphical solutions are achieved via numerical schemes, and the simulations for both the models are carried out through the computational software MATLAB. It is observed that both the fractional models of Caputo and Atangana–Baleanu give identical results for integer order, i.e. [Formula: see text]. By decreasing the fractional parameters, the concentration profile of the substrate [Formula: see text] takes more time to vanish. Moreover, binding of first substrate increases the reaction rate at another binding site in the case of extreme positive cooperation, while the opposite effect is noticed for the case of negative cooperativity. Furthermore, the effects of other parameters on concentration profiles of different species are shown graphically and discussed physically.


2021 ◽  
Vol 2128 (1) ◽  
pp. 012027
Author(s):  
Allam M. Allam ◽  
A.S. Ibrahim ◽  
Essam Nabil

Abstract This paper addresses a viable single loop PID controller on the bases of optimization algorithms for parallelly connected DC-DC converters to improve current sharing, improve the systems dynamics and guarantee good steady-state performance simultaneously. Because of inconvenience and lack of accuracy of Ziegler-Nichols rule in tuning PID controller parameters, an optimized controller design strategy with the purpose of enhancing the system performance is introduced in this paper. The PID is tuned by the traditional Ziegler -Nichols technique along with three other different algorithms: Genetic algorithm, whale algorithm and grey wolf algorithm. A comparison has been established between these algorithms based on the objective function value, execution time, overshoot, settling time and current sharing. The simulation results were collected to authenticate effectiveness of the proposed techniques and to evaluate the advantages of these optimization algorithms over the traditional tuning method.


2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. 384-384
Author(s):  
Linda Fried ◽  
Véronique Legault ◽  
Karen Bandeen-Roche ◽  
Nancy Presse ◽  
Pierrette Gaudreau ◽  
...  

Abstract Despite its widespread presence in older adults, frailty etiology is still unclear, being associated with dysregulation in diverse physiological systems. Here, we show evidence that frailty emerges from broad loss of homeostasis integrated through complex systems dynamics. Using the NuAge and WHAS cohorts, we calculated Mahalanobis distance-based physiological dysregulation in six systems and tested the breadth, diffuseness, and nonlinearity of associations between frailty and system-specific dysregulation. We found clear support for breadth of associations, but only partial support for diffuseness and nonlinearity: 1) physiological dysregulation is positively associated with frailty in many or all systems, depending on analyses; 2) the number of dysregulated systems or the total amount of dysregulation are more predictive than individual systems, but results only partially replicated across cohorts; 3) dysregulation trends are exponential, but not always significant. These results suggest, but do not fully prove, that frailty is an emergent property of complex systems dynamics.


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