scholarly journals Kriging Method-Based Return Prediction of Waste Electrical and Electronic Equipment in Reverse Logistics

2021 ◽  
Vol 11 (8) ◽  
pp. 3536
Author(s):  
Jun Lv ◽  
Shichang Du
Keyword(s):  
Mathematical Model ◽  
Spatial Correlation ◽  
Reverse Logistics ◽  
Minimum Variance ◽  
Electronic Equipment ◽  
Kriging Method ◽  
Analysis Method ◽  
Proposed Model ◽  
Spatial Correlation Structure

In reverse logistics, the accurate prediction of waste electrical and electronic equipment (WEEE) return amount is of great significance to guide electronic enterprises to formulate a reasonable recycling plan, remanufacturing production plan and inventory plan. However, due to the uncertainty of WEEE return, it is a challenge to accurately predict the WEEE return amount of recycling sites. Differently from the existing research methods aiming at the spatial correlation of the recycling amount of recycling sites, a spatial mathematical model based on Kriging method is proposed by this paper to predict the return amount of WEEE in reverse logistics. Based on the second-order randomness of the return amount, the spatial structure of the return amount of the recycling network is analyzed. According to the principle of unbiased prediction and minimum variance, the Kriging space mathematical model of WEEE return amount is derived, and the calculation process of three variograms is given. The results of Monte Carlo simulation and the case study on J company in Shanghai show that it is effective to utilize the Kriging method-based spatial mathematical model to predict the WEEE return of reverse logistics and analyze the spatial correlation structure of each recycling site. The proposed model can accurately predict the WEEE return amounts of unknown sites as well as those of the whole area through the known site data, which provides a novel analysis method and theoretical basis for the prediction of reverse logistics return amount.

A bi-level mathematical model for logistic management considering the evolutionary game with environmental feedbacks

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Peiman Ghasemi ◽  
Fariba Goodarzian ◽  
Angappa Gunasekaran ◽  
Ajith Abraham
Keyword(s):  
Mathematical Model ◽  
Lagrangian Relaxation ◽  
Evolutionary Games ◽  
Relaxation Method ◽  
Objective Functions ◽  
Content Type ◽  
Medical Centers ◽  
Location Routing ◽  
Proposed Model

PurposeThis paper proposed a bi-level mathematical model for location, routing and allocation of medical centers to distribution depots during the COVID-19 pandemic outbreak. The developed model has two players including interdictor (COVID-19) and fortifier (government). Accordingly, the aim of the first player (COVID-19) is to maximize system costs and causing further damage to the system. The goal of the second player (government) is to minimize the costs of location, routing and allocation due to budget limitations.Design/methodology/approachThe approach of evolutionary games with environmental feedbacks was used to develop the proposed model. Moreover, the game continues until the desired demand is satisfied. The Lagrangian relaxation method was applied to solve the proposed model.FindingsEmpirical results illustrate that with increasing demand, the values of the objective functions of the interdictor and fortifier models have increased. Also, with the raising fixed cost of the established depot, the values of the objective functions of the interdictor and fortifier models have raised. In this regard, the number of established depots in the second scenario (COVID-19 wave) is more than the first scenario (normal COVID-19 conditions).Research limitations/implicationsThe results of the current research can be useful for hospitals, governments, Disaster Relief Organization, Red Crescent, the Ministry of Health, etc. One of the limitations of the research is the lack of access to accurate information about transportation costs. Moreover, in this study, only the information of drivers and experts about transportation costs has been considered. In order to implement the presented solution approach for the real case study, high RAM and CPU hardware facilities and software facilities are required, which are the limitations of the proposed paper.Originality/valueThe main contributions of the current research are considering evolutionary games with environmental feedbacks during the COVID-19 pandemic outbreak and location, routing and allocation of the medical centers to the distribution depots during the COVID-19 outbreak. A real case study is illustrated, where the Lagrangian relaxation method is employed to solve the problem.

Model-Based EEG Analysis: Proposal and Verification of Mathematical Model for Application to Neurotechnology

2019 ◽  
Author(s):  
Kenyu Uehara ◽  
Takashi Saito
Keyword(s):  
Mathematical Model ◽  
Binary Classification ◽  
Least Square ◽  
Mental Condition ◽  
Support Vector ◽  
Model Parameters ◽  
Eeg Analysis ◽  
Analysis Method ◽  
Model Based ◽  
Proposed Model

Abstract We have modeled dynamics of EEG with one degree of freedom nonlinear oscillator and examined the relationship between mental state of humans and model parameters simulating behavior of EEG. At the IMECE conference last year, Our analysis method identified model parameters sequentially so as to match the waveform of experimental EEG data of the alpha band using one second running window. Results of temporal variation of model parameters suggested that the mental condition such as degree of concentration could be directly observed from the dynamics of EEG signal. The method of identifying the model parameters in accordance with the EEG waveform is effective in examining the dynamics of EEG strictly, but it is not suitable for practical use because the analysis (parameter identification) takes a long time. Therefore, the purpose of this study is to test the proposed model-based analysis method for general application as a neurotechnology. The mathematical model used in neuroscience was improved for practical use, and the test was conducted with the cooperation of four subjects. model parameters were experimentally identified approximately every one second by using least square method. We solved a binary classification problem of model parameters using Support Vector Machine. Results show that our proposed model-based EEG analysis is able to discriminate concentration states in various tasks with an accuracy of over 80%.

scholarly journals Inclusion of waste pickers in the reverse logistics of Waste Electrical and Electronic Equipment (WEEE) – the case study of Projeto Eco Eletro

2019 ◽  
Vol 51 ◽  
Author(s):  
Vivian Fernandes Marinho Ferreira ◽  
Sylmara Lopes Francelino Gonçalves-Dias ◽  
Isabella De Carvalho Vallin
Keyword(s):  
Reverse Logistics ◽  
Electronic Equipment ◽  
Waste Pickers

scholarly journals A Mathematical Model of COVID-19 Pandemic: A Case Study of Bangkok, Thailand

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Pakwan Riyapan ◽  
Sherif Eneye Shuaib ◽  
Arthit Intarasit
Keyword(s):  
Mathematical Model ◽  
Reproduction Number ◽  
Transmission Dynamics ◽  
Asymptotically Stable ◽  
Globally Asymptotically Stable ◽  
Proposed Model ◽  
Next Generation Matrix ◽  
Disease Free ◽  
The Basic Reproduction Number

In this study, we propose a new mathematical model and analyze it to understand the transmission dynamics of the COVID-19 pandemic in Bangkok, Thailand. It is divided into seven compartmental classes, namely, susceptible S , exposed E , symptomatically infected I s , asymptomatically infected I a , quarantined Q , recovered R , and death D , respectively. The next-generation matrix approach was used to compute the basic reproduction number denoted as R cvd 19 of the proposed model. The results show that the disease-free equilibrium is globally asymptotically stable if R cvd 19 < 1 . On the other hand, the global asymptotic stability of the endemic equilibrium occurs if R cvd 19 > 1 . The mathematical analysis of the model is supported using numerical simulations. Moreover, the model’s analysis and numerical results prove that the consistent use of face masks would go on a long way in reducing the COVID-19 pandemic.

An EOQ Model for Reuse and Recycling Considering the Balance of Supply and Demand

2015 ◽  
Vol 9 (3) ◽  
pp. 303-311 ◽  
Author(s):  
Tomomi Nonaka ◽  
◽  
Nobutada Fujii ◽  
Keyword(s):  
Inventory Management ◽  
Reverse Logistics ◽  
Supply And Demand ◽  
Computer Experiments ◽  
Demand And Supply ◽  
Product Demand ◽  
Eoq Model ◽  
Proposed Model ◽  
Using Data

Inventory management in reverse logistics is more complex than that in conventional logistics because of uncontrollable factors such as inventory levels increasing from reverse logistics, greater-than-expected disposal, and balance of supply and demand with changing market trends. This paper proposes a new economic order quantity (EOQ) model for reuse and recycling by expanding the EOQ model proposed by Dobos and Richter, 2004. The proposed model introduces a sequentially accumulated marginal reuse rate as a parameter in considering the balance of product demand and supply. The marginal reuse rate is calculated by using data on production distribution and disposal distribution of products for every discretized period. This model considers the sequence among recovery options: reuse, recycle and disposal. Parts are reused after having been inspected to determine whether they are reusable or not. Remaining nonreusable parts are recycled and any remaining nonrecycled parts disposed of. The extended EOQ model is applied to a case study using different scenarios for length of use and multiple generations of products. Results of computer experiments confirmed the effectiveness of the proposed method.

scholarly journals A mathematical model for human-to-human transmission of COVID-19: a case study for Turkey's data

2021 ◽  
Vol 18 (6) ◽  
pp. 9787-9805
Author(s):  
Süleyman Cengizci ◽  
◽  
Aslıhan Dursun Cengizci ◽  
Ömür Uğur ◽  
◽  
...  
Keyword(s):  
Mathematical Model ◽  
Total Population ◽  
Reproduction Number ◽  
Model Parameters ◽  
The Novel ◽  
Galerkin Finite Element Method ◽  
Galerkin Finite Element ◽  
Proposed Model ◽  
Novel Coronavirus

<abstract><p>In this study, a mathematical model for simulating the human-to-human transmission of the novel coronavirus disease (COVID-19) is presented for Turkey's data. For this purpose, the total population is classified into eight epidemiological compartments, including the super-spreaders. The local stability and sensitivity analysis in terms of the model parameters are discussed, and the basic reproduction number, $ R_{0} $, is derived. The system of nonlinear ordinary differential equations is solved by using the Galerkin finite element method in the FEniCS environment. Furthermore, to guide the interested reader in reproducing the results and/or performing their own simulations, a sample solver is provided. Numerical simulations show that the proposed model is quite convenient for Turkey's data when used with appropriate parameters.</p></abstract>

Measuring Elastic Properties of the Constituent Multilayer Coatings for Different Modulation Periods

2018 ◽  
Vol 10 (04) ◽  
pp. 1850046 ◽  
Author(s):  
Nadia Chakroun ◽  
Aymen Tekaya ◽  
Hedi Belhadjsalah ◽  
Tarek Benameur
Keyword(s):  
Mechanical Properties ◽  
Multilayer Coating ◽  
Multilayer Coatings ◽  
Multilayer Thin Films ◽  
Analysis Method ◽  
New Model ◽  
Proposed Model ◽  
Reverse Analysis ◽  
Dimensional Analysis Method

This paper is developed to characterize mechanical properties of multilayer coatings for different modulation periods. To that end, Dimensional Analysis Method (DAM) and Finite Element Method (FEM) are applied. Based on these methodologies, two dimensionless forms for the new model are expressed. Numerical nanoindentation tests are carried out for different set properties of multilayer coatings in order to validate the proposed model. Therefore, the mechanical properties of multilayer thin films are identified according to the reverse analysis algorithm. Hence, the input and the identified properties are consistent which ensure the effectiveness and the reliability of the proposed model. Moreover, a case study of Ti-TiN multilayer coating deposited on Zr-based metallic glasses was considered. As a result, the new model is useful for multilayer coatings for different modulation periods and can be used for technological applications.

scholarly journals A Hybrid Genetic Algorithm for Nurse Scheduling Problem considering the Fatigue Factor

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Atefeh Amindoust ◽  
Milad Asadpour ◽  
Samineh Shirmohammadi
Keyword(s):  
Genetic Algorithm ◽  
Mathematical Model ◽  
Hybrid Genetic Algorithm ◽  
Real Case ◽  
Scheduling Problem ◽  
Nurse Scheduling ◽  
Proposed Model ◽  
The World ◽  
New Situation

Nowadays and due to the pandemic of COVID-19, nurses are working under the highest pressure benevolently all over the world. This urgent situation can cause more fatigue for nurses who are responsible for taking care of COVID-19 patients 24 hours a day. Therefore, nurse scheduling should be modified with respect to this new situation. The purpose of the present research is to propose a new mathematical model for Nurse Scheduling Problem (NSP) considering the fatigue factor. To solve the proposed model, a hybrid Genetic Algorithm (GA) has been developed to provide a nurse schedule for all three shifts of a day. To validate the proposed approach, a randomly generated problem has been solved. In addition, to show the applicability of the proposed approach in real situations, the model has been solved for a real case study, a department in one of the hospitals in Esfahan, Iran, where COVID-19 patients are hospitalized. Consequently, a nurse schedule for May has been provided applying the proposed model, and the results approve its superiority in comparison with the manual schedule that is currently used in the department. To the best of our knowledge, it is the first study in which the proposed model takes the fatigue of nurses into account and provides a schedule based on it.

scholarly journals Model of transverse-transverse type piezoelectric transformer

2021 ◽  
Vol 102 (2) ◽  
pp. 96-109
Author(s):  
Volodymyr Medvid ◽  
Iryna Belyakova ◽  
Vadim Piscio ◽  
Serhii Lupenko
Keyword(s):  
Mathematical Model ◽  
Resonant Frequency ◽  
Electronic Equipment ◽  
Piezoelectric Medium ◽  
Design System ◽  
Constant Thickness ◽  
Flat Plates ◽  
Piezoelectric Transformer ◽  
Proposed Model ◽  
The Mathematical Model

The mathematical model of a piezoelectric transformer of the transverse-transverse type and describes the method of its construction has been presented. Although mathematical modeling programs for piezoelectric devices can achieve any predetermined modeling accuracy, the simulation results cannot be directly used in the development of electronic equipment, because the programs are not integrated with CADs, for this reason most often in calculations and in modeling circuits based on piezotransformers, the simplest equivalent circuit is used. But its adequately reflects currents and voltages in the piezotransformer circuit only in the vicinity of the operating resonant frequency. The proposed model is based on a one-dimensional approximation of the equations of state and dynamics of the piezoelectric medium for flat plates of constant thickness and width, which is obtained from a three-dimensional system of equations by averaging the width and thickness. While the usual approximate model often allows to model a piezotransformer with two pairs of electrodes and only in the vicinity of one resonant frequency, the model constructed in the article allows to take into account the presence of several electrodes on piezotransformer surfaces and their different relative positions on the upper and lower surfaces. 'esoplastin. Compared with the usual, the proposed model is more convenient for modeling by means of circuit modeling systems. In the developed model, the piezotransformer is represented as a set of interconnected sections that carry one pair or several pairs of electrodes on the surfaces. Also, in contrast to the usual, the proposed model allows to take into account the presence of several resonant frequencies of the piezotransformer, which allows more adequate modeling of electronic equipment that uses in its structure a piezoelectric transformer of the transverse type. On the basis of the mathematical model the scheme of substitution of separate sections of the piezoelectric transformer is constructed and formulas for calculation of parameters of elements of the scheme are given. In in the article as example the implementation of the developed model in the computer-aided design system MicroCAP has been showed.

A New Inverse Analysis Method for Identifying the Elastic Properties of Thin Films Considering Thickness and Substrate Effects Simultaneously

2017 ◽  
Vol 09 (07) ◽  
pp. 1750096 ◽  
Author(s):  
Nadia Chakroun ◽  
Aymen Tekaya ◽  
Hedi Belhadjsalah ◽  
Tarek Benameur
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Elastic Properties ◽  
Analysis Method ◽  
Innovative Methodology ◽  
Proposed Model ◽  
Indentation Tests ◽  
Reverse Analysis ◽  
Dimensional Analysis Method

This paper presents an innovative methodology for the measurement of the mechanical properties of thin films. The purpose is to identify the elastic properties of thin film materials considering the effects of thickness and substrate simultaneously. The new approach is based on the Dimensional Analysis Method (DAM) and the Finite Element Method (FEM) to develop the model’s explicit form. Using the reverse analysis method, numerical indentation tests were carried out to obtain the Young’s modulus of the film. Therefore, the identified film modulus was completely consistent with the input modulus, which ensures the reliability and the effectiveness of the proposed method. Moreover, a case study of TiN nanocoating deposited on Zr-Based Metallic Glasses was considered to validate the proposed model. This model is useful for thin film materials and can be used in different technological applications.

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