Multi-Objective Optimization Model for Thermal-Mechanical Treatment of Recycled Concrete Aggregate
Nam-Il Kim,
Un-song Pak,
Kyong-Chol Kim
Issue:
Volume 11, Issue 2, April 2023
Pages:
17-22
Received:
7 April 2023
Accepted:
15 May 2023
Published:
5 June 2023
Abstract: Efficient use of recycled concrete aggregates (RCA) produced using construction and demolition (C&D) waste can help solve many of the problems, such as reducing the consumption of huge amounts of natural aggregate and the generation of construction waste. Thermal-mechanical treatment is becoming a convenient method for recycling old concrete, but research to determine its implementation parameters is almost always conducted through experimental methods. In this paper, the MOO model, which takes heating temperature and mechanical treatment time as input variables and apparent density and water absorption rate as output variables, is derived to determine the experimental conditions for obtaining high-quality RCA and suggests a multi-objective optimization model for the thermal-mechanical treatment of recycled concrete aggregates. When using this mathematical model, under the same basic conditions (heating method, parameters of the treatment machine, etc.), the optimal thermal-mechanical treatment working parameters (heating temperature and mechanical treatment time) can be predicted in advance only by changing the boundary condition values without a large number of experiments. Although the experiment to prove the results of optimization modeling established in this paper has not been carried out, a mathematical method has been proposed to predict the experimental conditions which will help reduce the cost of high-quality RCA production or provide a scientific guarantee for the experiment.
Abstract: Efficient use of recycled concrete aggregates (RCA) produced using construction and demolition (C&D) waste can help solve many of the problems, such as reducing the consumption of huge amounts of natural aggregate and the generation of construction waste. Thermal-mechanical treatment is becoming a convenient method for recycling old concrete, but r...
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Optimal Control of COVID-19: Examining the Incidence of Contamination and Its Recurrence in Nigeria
Emmanuel Nwaeze,
Sunday Nwokpoku Aloke,
Louis Omenyi,
Michael Uchenna
Issue:
Volume 11, Issue 2, April 2023
Pages:
23-31
Received:
13 April 2023
Accepted:
27 April 2023
Published:
5 June 2023
Abstract: COVID-19 is an epidemic virus infection that is ravaging the world today. There are no pre-existing immunity and People were easily infected by this virus known as severe acute respiratory syndrome coronavirus (SARS-CoV-2) which caused Covid-19 (CDC, 2020). According to available data, the COVID-19 virus transmits most easily amongst people who are in proximity, typically within some feet (6) or meters. In this paper, we present the Susceptible – Exposed – Infected-Recovered (SEIR) epidemic model for the dynamics of COVID-19 outbreak and its optimal control in Nigeria. SEIR is characterized by a system of four non-linear differential equations. We established the existence and uniqueness of solutions of these equations. Using Nigeria’s COVID-19 data, we computed the basic reproduction number of the system. Further, an optimal control approach is performed to study the effect of control measure against the spread of the virus, the control level which minimizes the spread and optimal value of the control which maximizes the objective function. Through the application of Pontryagin’s Maximum Principle, we determined how the spread of the virus could be suppressed. The investigation shows that an effective strategy in combating the Covid-19 epidemic is adhering to the dictates of the control measures.
Abstract: COVID-19 is an epidemic virus infection that is ravaging the world today. There are no pre-existing immunity and People were easily infected by this virus known as severe acute respiratory syndrome coronavirus (SARS-CoV-2) which caused Covid-19 (CDC, 2020). According to available data, the COVID-19 virus transmits most easily amongst people who are...
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