scholarly journals Application of optimal control to tuberculosis model with parameter estimations: Bayesian approach

2021 ◽  
Vol 47 (2) ◽  
pp. 698-709
Author(s):  
Goodluck M Mlay ◽  
Alfred K Hugo
Keyword(s):  
Focal Point ◽  
Control Strategies ◽  
Control Mechanisms ◽  
Optimum Conditions ◽  
Parameter Estimations ◽  
Tuberculosis Model ◽  
Keywords Tuberculosis ◽  
Latent Tb ◽  
Education Campaigns ◽  
The Pontryagin Maximum Principle

In this paper, one-strain tuberculosis (TB) model with two control mechanisms, education campaigns and chemoprophylaxis of TB-infected patients, was studied to determine their effects on the reduction of latent and active TB cases. In the case of analysis, boundedness and positivity of the model solutions were carried out to determine the biological feasibility of the study. Besides, the calibration of the parameters by utilizing the identifiability technique through the Markov chain Monte Carlo (MCMC) was thoroughly analysed. The optimum conditions for controlling TB were derived from the Pontryagin Maximum Principle. The numerical simulations were carried out using the forward-back sweep method with the help of the Runge-Kutta fourth-order numerical schemes. Simulation results showed that the education campaigns strategy is more effective in reducing TB infections than the chemoprophylaxis of TB-infected individuals. The combination of the two control strategies reduces a significant number of infections than when each strategy is used on its own. To minimize the transmission of TB from the community, we recommend the education campaigns strategy be a focal point and treatment of latent TB to be paired with the treatment of active TB cases. Keywords: Tuberculosis, Education campaigns, Chemoprophylaxis, MCMC

From the Modeling of Parallel Relational Query Processing to Query Optimization and Simulation

1998 ◽  
Vol 08 (01) ◽  
pp. 51-62 ◽  
Author(s):  
Lionel Brunie ◽  
Harald Kosch ◽  
Wolfgang Wohner
Keyword(s):  
Query Processing ◽  
Query Optimization ◽  
Petri Net ◽  
Control Strategies ◽  
Optimization Methods ◽  
Control Flow ◽  
Control Mechanisms ◽  
Time Control ◽  
Run Time ◽  
High Level

This paper presents a novel theoretical model for representing parallel relational query processing. It is based on two components. First, a scheme graph, called DPL graph, describes all possible execution dependencies between operators, including communication and run-time control mechanisms. Second, a timed high-level Petri net is used for modeling the data- and control flow of DPL graphs. Our model provides the framework for implementing a parallel query optimizer which is able to access sub-search spaces not yet considered. Furthermore, based on the DPL graphs and its related timed high-level Petri net, a simulation environment has been designed for testing run-time control strategies as well as query optimization methods.

scholarly journals Optimal control problem for a tuberculosis model with multiple infectious compartments and time delays

2021 ◽  
Vol 11 (1) ◽  
pp. 75-91
Author(s):  
Mohamed Elhia ◽  
Omar Balatif ◽  
Lahoucine Boujallal ◽  
Mostafa Rachik
Keyword(s):  
Optimal Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Time Delays ◽  
Control Strategies ◽  
Multiple Time ◽  
Optimal Controls ◽  
Loss To Follow Up ◽  
Tuberculosis Model

In this paper, we formulate an optimal control problem based on a tuberculosis model with multiple infectious compartments and time delays. In order to have a more realistic model that allows highlighting the role of detection, loss to follow-up and treatment in TB transmission, we propose an extension of the classical SEIR model by dividing infectious patients in the compartment (I) into three categories: undiagnosed infected (I), diagnosed patients who are under treatment (T) and diagnosed patients who are lost to follow-up (L). We incorporate in our model delays representing the incubation period and the time needed for treatment. We also introduce three control variables in our delayed system which represent prevention, detection and the efforts that prevent the failure of treatment. The purpose of our control strategies is to minimize the number of infected individuals and the cost of intervention. The existence of the optimal controls is investigated, and a characterization of the three controls is given using the Pontryagin's maximum principle with delays. To solve numerically the optimality system with delays, we present an adapted iterative method based on the iterative Forward-Backward Sweep Method (FBSM). Numerical simulations performed using Matlab are also provided. They indicate that the prevention control is the most effective one. To the best of our knowledge, it is the first work to apply optimal control theory to a TB model which considers infectious patients diagnosis, loss to follow-up phenomenon and multiple time delays.

scholarly journals Can medication mitigate the need for a strict lock down?: A mathematical study of control strategies for COVID-19 infection

2020 ◽  
Author(s):  
Mohsin Ali ◽  
Mudassar Imran ◽  
Adnan Khan
Keyword(s):  
Reproduction Number ◽  
Virus Disease ◽  
Control Strategies ◽  
Effective Control ◽  
Control Mechanisms ◽  
Mathematical Study ◽  
Epidemic Curve ◽  
The World ◽  
Asymptomatic Individuals ◽  
Pharmaceutical Interventions

Abstract BackgroundCOVID-19 is a pandemic that has swept across the world in 2020. To date the only effective control mechanisms were non-pharmaceutical interventions, however there have been encouraging reports regarding possible medication in the literature, with emergency approval given to some drugs in various countries.MethodsWe formulate a deterministic epidemic model to study the effects of medication on the transmission dynamics of Corona Virus Disease (COVID-19). We are especially interested in how the availability of medication could change the necessary quarantine measures for effective control of the disease. We model the transmission by extending the SEIR model to include asymptomatic, quarantined, isolated and medicated population compartments.ResultsWe calculate the basic reproduction number R0 and show that for R0<1 the disease dies out and for R0>1 the disease is endemic. Using sensitivity analysis we establish that R0 is most sensitive to the rates of quarantine and medication. We also study how the effectiveness and the rate of medication along with the quarantine rate affect R0. We devise optimal quarantine, medication and isolation strategies, noting that availability of medication reduces the duration and severity of the lock-down needed for effective disease control.ConclusionOur study also reinforces the idea that with the availability of medication, while the severity of the lock downs can be eased over time some social distancing protocols need to be observed, at least till a vaccine is found. We also analyze the COVID-19 outbreak data for four different countries, in two of these, India and Pakistan the curve is still rising, and in he other two, Italy and Spain, the epidemic curve is now falling due to effective quarantine measures. We provide estimates of R0 and the proportion of asymptomatic individuals in the population for these countries.

scholarly journals Electromagnetically Compatible and Virtual Flux DPC Control Techniques for 3-Phase Distributed Generation Fed by Active Rectifier

2020 ◽  
Vol 9 (3) ◽  
pp. 2295-2301
Keyword(s):  
Distributed Generation ◽  
Control Strategies ◽  
Harmonic Distortion ◽  
Total Harmonic Distortion ◽  
Control Mechanisms ◽  
Direct Power ◽  
Control Techniques ◽  
Active Rectifier ◽  
Virtual Flux ◽  
Active Rectifiers

This paper gives different control mechanisms comparison for active rectifiers fed grid connected 3-phase distributed generation systems from non-conventional energy sources. The control strategies presented here are Direct Power Control, 2 other DPC methods DPC to reduce CM voltage emissions that are EMC-I-DPC and EMC-II-DPC. Another two strategies are also presented with a concept of virtual flux i.e EMC-I-VF-DPC and EMC-II-VF-DPC. MATLAB/Simulink software is used to implement the so called techniques and the parameters like are injected current into electric grid , %Total harmonic distortion of current injected vs. generated power, %Total harmonic distortion of current injected vs DC link voltage (Vdc) and %Total harmonic distortion of current injected vs CM voltages are shown.

scholarly journals Towards practical dynamic induction control of wind farms: analysis of optimally controlled wind-farm boundary layers and sinusoidal induction control of first-row turbines

2018 ◽  
Author(s):  
Wim Munters ◽  
Johan Meyers
Keyword(s):  
Optimal Control ◽  
Wind Farm ◽  
Control Strategies ◽  
Computational Cost ◽  
Wind Farms ◽  
Practical Implementation ◽  
Control Mechanisms ◽  
Optimal Controls ◽  
Eddy Simulation ◽  
Wake Interactions

Abstract. Wake interactions between wind turbines in wind farms lead to reduced energy extraction in downstream rows. In recent work, optimization and large-eddy simulation were combined with optimal dynamic induction control of wind farms to study the mitigation of these effects, showing potential power gains of up to 20 % (Munters &amp; Meyers 2017 Phil Trans R Soc A 375, 20160100, doi:10.1098/rsta.2016.0100). However, the computational cost associated with these optimal control simulations impedes practical implementation of this approach. Furthermore, the resulting control signals optimally react to the specific instantaneous turbulent flow realizations in the simulations, so that they cannot be simply used in general. The current work focuses on the detailed analysis of the optimization results of Munters &amp; Meyers, with the aim to identify simplified control strategies that mimic the optimal control results and can be used in practice. The analysis shows that wind-farm controls are optimized in a parabolic manner with little upstream propagation of information. Moreover, turbines can be classified into first-row, intermediate-row, and last-row turbines based on their optimal control dynamics. At the moment, the control mechanisms for intermediate-row turbines remain unclear, but for first-row turbines we find that the optimal controls increase wake mixing by periodic shedding of vortex rings. This behavior can be mimicked with a simple sinusoidal thrust control strategy for first-row turbines, resulting in robust power gains for turbines in the entrance region of the farm.

scholarly journals Robustness and the evolution of length control strategies in the type III secretion system and flagellar hook

2019 ◽  
Author(s):  
Maulik K. Nariya ◽  
Abhishek Mallela ◽  
Jack J. Shi ◽  
Eric J. Deeds
Keyword(s):  
Type Iii Secretion ◽  
Average Length ◽  
Control Strategies ◽  
Bacterial Species ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Control Mechanisms ◽  
Switching Mechanism ◽  
Type Iii ◽  
Trade Offs

AbstractBacteria construct many structures, like the flagellar hook and the type III secretion system, that aid in crucial processes such as locomotion and pathogenesis. Experimental work has suggested two competing mechanisms bacteria could use to regulate length in these structures: the “ruler” mechanism and the “substrate switching” mechanism. In this work, we constructed a mathematical model of length control based on the ruler mechanism, and found that the predictions of this model are consistent with experimental data not just for the scaling of the average length with the ruler protein length, but also the variance. Interestingly, we found that the ruler mechanism allows for the evolution of needles with large average lengths without the concomitant large increase in variance that occurs in the substrate switching mechanism. These findings shed new light on the trade-offs that may have lead to the evolution of different length control mechanisms in different bacterial species.

Strategies for the Control of Balance During Locomotion

2018 ◽  
Vol 7 (1) ◽  
pp. 18-25 ◽  
Author(s):  
Hendrik Reimann ◽  
Tyler Fettrow ◽  
John J. Jeka
Keyword(s):  
Degrees Of Freedom ◽  
Neural Control ◽  
Control Strategies ◽  
Mechanical Effect ◽  
Space Representation ◽  
Control Mechanisms ◽  
Step Width ◽  
Foot Placement ◽  
The Central Nervous System ◽  
Phase Space Representation

The neural control of balance during locomotion is currently not well understood, even in the light of considerable advances in research on balance during standing. In this paper, we lay out the control problem for this task and present a list of different strategies available to the central nervous system to solve this problem. We discuss the biomechanics of the walking body, using a simplified model that iteratively gains degrees of freedom and complexity. Each addition allows for different control strategies, which we introduce in turn: foot placement shift, ankle strategy, hip strategy, and push-off modulation. The dynamics of the biomechanical system are discussed using the phase space representation, which allows illustrating the mechanical effect of the different control mechanisms. This also enables us to demonstrate the effects of common general stability strategies, such as increasing step width and cadence.

scholarly journals Unifying Privacy Policy Detection

2021 ◽  
Vol 2021 (4) ◽  
pp. 480-499
Author(s):  
Henry Hosseini ◽  
Martin Degeling ◽  
Christine Utz ◽  
Thomas Hupperich
Keyword(s):  
Language Processing ◽  
Focal Point ◽  
Future Research ◽  
Data Sets ◽  
Control Mechanisms ◽  
Privacy Policies ◽  
Data Practices ◽  
Specific Analysis ◽  
Starting Point ◽  
Core Part

Abstract Privacy policies have become a focal point of privacy research. With their goal to reflect the privacy practices of a website, service, or app, they are often the starting point for researchers who analyze the accuracy of claimed data practices, user understanding of practices, or control mechanisms for users. Due to vast differences in structure, presentation, and content, it is often challenging to extract privacy policies from online resources like websites for analysis. In the past, researchers have relied on scrapers tailored to the specific analysis or task, which complicates comparing results across different studies. To unify future research in this field, we developed a toolchain to process website privacy policies and prepare them for research purposes. The core part of this chain is a detector module for English and German, using natural language processing and machine learning to automatically determine whether given texts are privacy or cookie policies. We leverage multiple existing data sets to refine our approach, evaluate it on a recently published longitudinal corpus, and show that it contains a number of misclassified documents. We believe that unifying data preparation for the analysis of privacy policies can help make different studies more comparable and is a step towards more thorough analyses. In addition, we provide insights into common pitfalls that may lead to invalid analyses.

On the Open-Loop and Feedback Processes That Underlie the Formation of Trajectories During Visual and Nonvisual Locomotion in Humans

2009 ◽  
Vol 102 (5) ◽  
pp. 2800-2815 ◽  
Author(s):  
Quang-Cuong Pham ◽  
Halim Hicheur
Keyword(s):  
Feedback Control ◽  
Control Strategies ◽  
Open Loop ◽  
Optimal Feedback Control ◽  
Control Mechanisms ◽  
Experimental Conditions ◽  
Optimal Feedback ◽  
On Line ◽  
Kinematic Properties

We investigated the nature of the control mechanisms at work during goal-oriented locomotion. In particular, we tested the effects of vision, locomotor speed, and the presence of via points on the geometric and kinematic properties of locomotor trajectories. We first observed that the average trajectories recorded in visual and nonvisual locomotion were highly comparable, suggesting the existence of vision-independent processes underlying the formation of locomotor trajectories. Then by analyzing and comparing the variability around the average trajectories across different experimental conditions, we were able to demonstrate the existence of on-line feedback control in both visual and nonvisual locomotion and to clarify the relations between visual and nonvisual control strategies. Based on these insights, we designed a model in which maximum-smoothness and optimal feedback control principles account, respectively, for the open-loop and feedback processes. Taken together, the experimental and modeling findings provide a novel understanding of the nature of the motor, sensory, and “navigational” processes underlying goal-oriented locomotion.

scholarly journals Targeting Non-Replicating Mycobacterium tuberculosis and Latent Infection: Alternatives and Perspectives (Mini-Review)

2021 ◽  
Vol 22 (24) ◽  
pp. 13317
Author(s):  
Anna Egorova ◽  
Elena G. Salina ◽  
Vadim Makarov
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Small Molecules ◽  
Drug Targets ◽  
Latent Infection ◽  
Early Stage ◽  
Control Strategies ◽  
Latent Tuberculosis ◽  
Ltbi Treatment ◽  
Latent Tb ◽  
Current Guidelines

Latent tuberculosis infection (LTBI) represents a major challenge to curing TB disease. Current guidelines for LTBI management include only three older drugs and their combinations—isoniazid and rifamycins (rifampicin and rifapentine). These available control strategies have little impact on latent TB elimination, and new specific therapeutics are urgently needed. In the present mini-review, we highlight some of the alternatives that may potentially be included in LTBI treatment recommendations and a list of early-stage prospective small molecules that act on drug targets specific for Mycobacterium tuberculosis latency.

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