scholarly journals ADAPTIVE GRADIENT METHOD FOR THE OPTIMAL CONTROL OF AN ANTICANCER THERAPY MODEL

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Gustavo Taiji Naozuka ◽  
Heber Lima da Rocha ◽  
Regina Célia Cerqueira de Almeida
Keyword(s):  
Optimal Control ◽  
Computational Models ◽  
Control Point ◽  
Growth Dynamics ◽  
Adaptive Method ◽  
Maximum Tolerated Dose ◽  
Variation Method ◽  
Computational Time ◽  
Optimal Controls ◽  
The Impact

Cancer is a set of diseases whose mechanisms of emergence and growth are not completely known. Mathematical and computational models aim to contribute to a better understanding of these mechanisms in tumor dynamics. They can also be used to analyze the impact of anticancer therapeutic protocols. In this sense, we investigate a mathematical model of tumor growth dynamics from the optimal control point of view. We apply the Switching-Time-Variation method to solve the control problem and modify its implementation in order to reduce computational time. Our results show that the execution time of the adaptive method is significantly shorter, and optimal controls for the observed scenario are of the bang-bang type with administration by maximum tolerated dose. The analysis also suggests that the application of another drug capable of acting on resistant tumor cells is required.

scholarly journals Transmission Dynamics of Hepatitis C with Control Strategies

2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
Adnan Khan ◽  
Sultan Sial ◽  
Mudassar Imran
Keyword(s):  
Optimal Control ◽  
Hepatitis C ◽  
Deterministic Model ◽  
Control Strategies ◽  
Endemic Equilibrium ◽  
Transmission Dynamics ◽  
Critical Parameters ◽  
Optimal Controls ◽  
Infected Population ◽  
The Impact

We present a rigorous mathematical analysis of a deterministic model, for the transmission dynamics of hepatitis C, using a standard incidence function. The infected population is divided into three distinct compartments featuring two distinct infection stages (acute and chronic) along with an isolation compartment. It is shown that for basic reproduction number R0≤1, the disease-free equilibrium is locally and globally asymptotically stable. The model also has an endemic equilibrium for R0>1. Uncertainty and sensitivity analyses are carried out to identify and study the impact of critical parameters on R0. In addition, we have presented the numerical simulations to investigate the influence of different important parameters on R0. Since we have a locally stable endemic equilibrium, optimal control is applied to the deterministic model to reduce the total infected population. Two different optimal control strategies (vaccination and isolation) are designed to control the disease and reduce the infected population. Pontryagin’s Maximum Principle is used to characterize the optimal controls in terms of an optimality system which is solved numerically. Numerical results for the optimal controls are compared against the constant controls and their effectiveness is discussed.

scholarly journals A B-Spline approach on Dynamic response of bridges subjected to moving vehicles

2020 ◽  
Vol 4 (4) ◽  
pp. 888-900
Author(s):  
Vuong Nguyen Van Do ◽  
Hai Duc Cam Vo ◽  
Nam Tuan Phuong Le
Keyword(s):  
Control Point ◽  
Beam Theory ◽  
Equation System ◽  
Numerical Approach ◽  
Computational Time ◽  
Moving Vehicle ◽  
B Spline ◽  
Moving Vehicles ◽  
Spline Basis ◽  
The Impact

Dynamic analysis of various structures subjected to moving vehicles using the Euler-Bernoulli formulation is presented in this paper. The method employs a new numerical approach in which the B-Spline basis functions are suggested for the computational implementation. The Dalambert`s principle is used to set up the moving differential equation system acting on vehicle and beam solving by the Newmark's modified average acceleration. The rotation-free technique has been taken account into the general formulation on Euler Euler-Bernoulli beam theory by using only one vertical deflection unknown and ignoring the rotational variable considering for each control point. The validations of the proposed method considered by a complicated moving vehicle are compared to the precisely analytical results. With the most existing methods of finite element method (FEM) and readily exact solutions, the present technique indicated that it could be an effective method in suitably simulating the interaction of the bridge structures and complicated vehicles. Through the obtained numerical results, this study gives recommendations and proper measures to minimize the impact of vehicle on long span structures and significantly reduce the computational time and cost when analyzing and assess to these practical structures.

scholarly journals Resource Allocation in Two-Patch Epidemic Model with State-Dependent Dispersal Behaviors Using Optimal Control

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1087
Author(s):  
Sunmi Lee ◽  
Okbun Baek ◽  
Luis Melara
Keyword(s):  
Optimal Control ◽  
Residence Time ◽  
Epidemic Model ◽  
Disease Transmission ◽  
Optimal Strategies ◽  
Control Measures ◽  
Optimal Controls ◽  
State Variables ◽  
State Dependent ◽  
The Impact

A two-patch epidemic model is considered in order to assess the impact of virtual dispersal on disease transmission dynamics. The two-patch system models the movement of individuals between the two-patches using a residence-time matrix P, where P depends on both residence times and state variables (infected classes). In this work, we employ this approach to a general two-patch SIR model in order to investigate the effect of state dependent dispersal behaviors on the disease dynamics. Furthermore, optimal control theory is employed to identify and evaluate patch-specific control measures aimed at reducing disease prevalence at a minimal cost. Optimal policies are computed under various dispersal scenarios (depending on the different residence-time matrix configurations). Our results suggest there is a reduction of the outbreak and the proportion of time spent by individuals in a patch exhibits less fluctuations in the presence of patch-specific optimal controls. Furthermore, the optimal strategies for each patch differ depending on the type of dispersal behavior and the different infection rate in a patch. In all of our results, we obtain that the optimal strategies reduce the number of infections per patch.

scholarly journals Presentation of Malaria Epidemics Using Multiple Optimal Controls

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Abid Ali Lashari ◽  
Shaban Aly ◽  
Khalid Hattaf ◽  
Gul Zaman ◽  
Il Hyo Jung ◽  
...  
Keyword(s):  
Optimal Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Control Measures ◽  
Optimal Controls ◽  
Uniqueness Results ◽  
Adjoint Variables ◽  
Reduction Strategies ◽  
Parameter Values ◽  
The Impact

An existing model is extended to assess the impact of some antimalaria control measures, by re-formulating the model as an optimal control problem. This paper investigates the fundamental role of three type of controls, personal protection, treatment, and mosquito reduction strategies in controlling the malaria. We work in the nonlinear optimal control framework. The existence and the uniqueness results of the solution are discussed. A characterization of the optimal control via adjoint variables is established. The optimality system is solved numerically by a competitive Gauss-Seidel-like implicit difference method. Finally, numerical simulations of the optimal control problem, using a set of reasonable parameter values, are carried out to investigate the effectiveness of the proposed control measures.

scholarly journals Controlled singular evolution equations and Pontryagin type maximum principle with applications

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Xiao-Li Ding ◽  
Iván Area ◽  
Juan J. Nieto
Keyword(s):  
Optimal Control ◽  
Maximum Principle ◽  
Control Problem ◽  
Evolution Equations ◽  
Optimal Control Problems ◽  
Type Theorem ◽  
Control Problems ◽  
Optimal Controls ◽  
Special Cases ◽  
The Impact

<p style='text-indent:20px;'>Due to the propagation of new coronavirus (COVID-19) on the community, global researchers are concerned with how to minimize the impact of COVID-19 on the world. Mathematical models are effective tools that help to prevent and control this disease. This paper mainly focuses on the optimal control problems of an epidemic system governed by a class of singular evolution equations. The mild solutions of such equations of Riemann-Liouville or Caputo types are special cases of the proposed equations. We firstly discuss well-posedness in an appropriate functional space for such equations. In order to reduce the cost caused by control process and vaccines, and minimize the total number of susceptible people and infected people as much as possible, an optimal control problem of an epidemic system is presented. And then for associated control problem, we use a generalized Liapunov type theorem and the spike perturbation technique to obtain a Pontryagin type maximum principle for its optimal controls. In order to derive the maximum principle for an optimal control problems, some techniques from analytical semigroups are employed to overcome the difficulties. Finally, we discuss the potential applications.</p>

scholarly journals Evaluation of the impact of compliance of precast discs of overlapping on the work of the frame of a multi-storey building

2019 ◽  
Vol 97 ◽  
pp. 04022
Author(s):  
Nikolay Trekin ◽  
Emil Kodysh ◽  
Alexander Bybka ◽  
Alexander Yamalov ◽  
Nikita Konkov
Keyword(s):  
Economic Performance ◽  
Computational Models ◽  
Precast Concrete ◽  
Building Frames ◽  
Frame Building ◽  
Numerical Studies ◽  
Frame Buildings ◽  
The Impact ◽  
Structural Solutions ◽  
Storey Building

The article provides an analysis and justification of the need to take into account the compliance of discs of overlapping and coatings when calculating frames from precast concrete structures. Previously conducted full-scale experiments showed that the rigidity of the precast overlapping with full filling of the seams, in comparison with the monolithic overlapping, decreases by 3-15 times due to the ductility of the joints. The use of refined computational models of structural solutions for frames, which take into account the compliance of the conjugations of elements, makes it possible to trace possible redistribution of efforts. Such an approach when reconstructing, it is possible to optimally select and calculate the enforcement of structure, and on new designing, to increase reliability and / or improve the economic performance of frame buildings. According to the results of analytical studies, formulas were adopted for the parameters that allow one to take into account the overall compliance of overlapping disks and coatings in computational models of building frames. Numerical studies on the computational model of a frame building made it possible to evaluate the effect of accounting for compliance on the stress-strain state of a multi-storey frame.

scholarly journals Seaweed aquaculture: a preliminary assessment of biosecurity measures for controlling the ice-ice syndrome and pest outbreaks of a Kappaphycus farm

2021 ◽  
Author(s):  
Cicilia S. B. Kambey ◽  
Iona Campbell ◽  
Elizabeth J. Cottier-Cook ◽  
Adibi R. M. Nor ◽  
Azhar Kassim ◽  
...  
Keyword(s):  
Hazard Analysis ◽  
Kappaphycus Alvarezii ◽  
Control Point ◽  
Control Measures ◽  
Seaweed Aquaculture ◽  
Critical Control Point ◽  
Management Measures ◽  
Long Line ◽  
Pest Outbreaks ◽  
The Impact

AbstractThe application of biosecurity in seaweed aquaculture plays an important role in reducing the impact of disease and pest outbreaks. The continuous occurrence of seaweed pests including the macroalgal epiphytes, epi-endophytic filamentous algae and biofilms on Kappaphycus farms may also potentially induce further incidences of the ice-ice syndrome. In this study, on-farm biosecurity management measures were tested on the commercially grown seaweeds Kappaphycus malesianus and Kappaphycus alvarezii during peak ice-ice season at Gallam-Gallam Village, Sabah, Malaysia. The investigation was focused on preventative control measures including the early detection of the ice-ice syndrome and pests through propagule health checks, regular cleaning of the crop thallus and associated long-line ropes and monitoring of the environment. Farm procedures and practices were also assessed in terms of their biosecurity ‘risk’ using the hazard analysis and critical control point (HCCAP) approach. Observations were replicated in two different farm management systems; one system adopted routine biosecurity measures and the other had no biosecurity measures. The results showed that the ice-ice syndrome and pest outbreak was significantly decreased by 60–75% for K. malesianus and 29–71% for K. alvarezii at the farm which adopted the routine biosecurity measures compared with the no biosecurity treatment. The biosecurity measures also significantly improved growth rate and seaweed quality. The infection levels of the epi-endophyte Melanothamnus sp. contributed to the ice-ice syndrome in K. malesianus, whilst the epiphyte coverage was correlated to the ice-ice incidence in K. alvarezii. This study provides the first evidence of biosecurity management measures significantly decreasing the incidence of the ice-ice syndrome and pests on a commercial seaweed farm.

scholarly journals Model-Based Control of Torque and Nitrogen Oxide Emissions in a Euro VI 3.0 L Diesel Engine through Rapid Prototyping

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1107
Author(s):  
Stefano d’Ambrosio ◽  
Roberto Finesso ◽  
Gilles Hardy ◽  
Andrea Manelli ◽  
Alessandro Mancarella ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Rapid Prototyping ◽  
Nitrogen Oxide ◽  
Thermal State ◽  
Pollutant Emissions ◽  
Computational Time ◽  
Nox Emissions ◽  
Model Based ◽  
Brake Mean Effective Pressure ◽  
The Impact

In the present paper, a model-based controller of engine torque and engine-out Nitrogen oxide (NOx) emissions, which was previously developed and tested by means of offline simulations, has been validated on a FPT F1C 3.0 L diesel engine by means of rapid prototyping. With reference to the previous version, a new NOx model has been implemented to improve robustness in terms of NOx prediction. The experimental tests have confirmed the basic functionality of the controller in transient conditions, over different load ramps at fixed engine speeds, over which the average RMSE (Root Mean Square Error) values for the control of NOx emissions were of the order of 55–90 ppm, while the average RMSE values for the control of brake mean effective pressure (BMEP) were of the order of 0.25–0.39 bar. However, the test results also highlighted the need for further improvements, especially concerning the effect of the engine thermal state on the NOx emissions in transient operation. Moreover, several aspects, such as the check of the computational time, the impact of the controller on other pollutant emissions, or on the long-term engine operations, will have to be evaluated in future studies in view of the controller implementation on the engine control unit.

scholarly journals Evaluation of a Coupled Model to Predict the Impact of Adaptive Behaviour in the Thermal Sensation of Occupants of Naturally Ventilated Buildings in Warm-Humid Regions

2020 ◽  
Vol 13 (1) ◽  
pp. 255
Author(s):  
Luciano C. de Faria ◽  
Marcelo A. Romero ◽  
Lúcia F. S. Pirró
Keyword(s):  
Computational Models ◽  
Thermal Sensation ◽  
Coupled Model ◽  
Adaptive Behaviour ◽  
Humid Climate ◽  
Clothing Insulation ◽  
Tropical Regions ◽  
Naturally Ventilated Buildings ◽  
Adaptive Behaviours ◽  
The Impact

Improving indoor environment quality and making urban centres in tropical regions more sustainable has become a challenge for which computational models for the prediction of thermal sensation for naturally ventilated buildings (NVBs) have major role to play. This work performed analysis on thermal sensation for non-residential NVBs located in Brazilian tropical warm-humid climate and tested the effectiveness of suggested adaptive behaviours to mitigate warm thermal sensation. The research method utilized transient computational fluid dynamics models coupled with a dynamic model for human thermophysiology to predict thermal sensation. The calculated results were validated with comparison with benchmark values from questionnaires and from field measurements. The calculated results for dynamic thermal sensation (DTS) seven-point scale showed higher agreement with the thermal sensation vote than with the predicted mean vote. The test for the suggested adaptive behaviours considered reducing clothing insulation values from 0.18 to 0.32 clo (reducing DTS from 0.1 to 0.9), increasing the air speed in 0.9 m/s (reducing DTS from 0.1 to 0.9), and applying both suggestions together (reducing DTS from 0.1 to 1.3) for five scenarios with operative temperatures spanning 34.5–24.0 °C. Results quantified the tested adaptive behaviours’ efficiency showing applicability to improve thermal sensation from slightly-warm to neutral.

scholarly journals Braided composite stent for peripheral vascular applications

2020 ◽  
Vol 9 (1) ◽  
pp. 1137-1146
Author(s):  
Qingli Zheng ◽  
Pengfei Dong ◽  
Zhiqiang Li ◽  
Ying Lv ◽  
Meiwen An ◽  
...  
Keyword(s):  
Computational Models ◽  
Surface Coverage ◽  
Mechanical Performance ◽  
Wire Diameter ◽  
Orthogonal Experimental Design ◽  
Braided Composite ◽  
Nitinol Wire ◽  
Radial Strength ◽  
Braiding Angle ◽  
The Impact

AbstractBraided composite stent (BCS), woven with nitinol wires and polyethylene terephthalate (PET) strips, provides a hybrid design of stent. The mechanical performance of this novel stent has not been fully investigated yet. In this work, the influence of five main design factors (number of nitinol wires, braiding angle, diameter of nitinol wire, thickness and stiffness of the PET strip) on the surface coverage, radial strength, and flexibility of the BCS were systematically studied using computational models. The orthogonal experimental design was adopted to quantitatively analyze the sensitivity of multiple factors using the minimal number of study cases. Results have shown that the nitinol wire diameter and the braiding angle are two most important factors determining the mechanical performance of the BCS. A larger nitinol wire diameter led to a larger radial strength and less flexibility of the BCS. A larger braiding angle could provide a larger radial strength and better flexibility. In addition, the impact of the braiding angle decreased when the stent underwent a large deformation. At the same time, the impact of the PET strips increased due to the interaction with nitinol wires. Moreover, the number of PET strips played an important role in the surface coverage. This study could help understand the mechanical performance of BCS stent and provides guidance on the optimal design of the stent targeting less complications.

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