scholarly journals Proposal of a Dynamic Algorithm for the Maintenance and Vehicle Routing Problem with Time Windows

Ingeniería ◽  
2022 ◽  
Vol 26 (3) ◽  
pp. 436-449
Author(s):  
Carlos Andrés López Ayala ◽  
Wilson Jurado Valbuena ◽  
Eduyn Ramiro Lopez Santana
Keyword(s):  
Performance Measures ◽  
Response Times ◽  
Mathematical Problem ◽  
Essential Element ◽  
Computational Time ◽  
Future Research ◽  
Two Phase ◽  
Routing Problem ◽  
Planning And Scheduling ◽  
Dynamic Algorithm

Context:  In the context of business organizations, every process in which the product is immersed has a cost and time associated with it. The area of maintenance planning and scheduling is no exception; however, it is an aspect in which few companies specialize, tending to be outsourced. In this sense, the application of combinatorial models is a tool with a high potential to improve the overall performance of the organization through the understanding of the integral maintenance process. Method: A two-phase (maintenance and routing) dynamic algorithm is proposed which considers a set of clients distributed in a maintenance network (distance), where each of the technicians start from the same central node (depot), which, in turn, is the endpoint of each assigned route. The objective is to minimize the total cost associated with the development of preventive and corrective maintenance of all machines to be evaluated. With this purpose, the formulation of the mathematical problem for each of the phases and its interrelation method is proposed. Then, performance measures are expressed to evaluate the achieved objectives. Results: The results satisfy a consistent alternative for the resolution of problems of the NP-Hard type, which generates a high level of complexity to the model. That is, it proposes a tool for solving problems of these characteristics in low computational response times and with appealing results. Conclusions: The combined maintenance and routing model using a dynamic algorithm addresses the maintenance and routing problem satisfactorily. The model shows good results with respect to the comparison optimization model in percentage gaps of performance measures lower than 5%. As for the computational time required, a reduction of up to 98% was achieved, which makes it an ideal alternative for highly complex scenarios. Finally, achieving a higher level of characterization, employing multi-objective decision criteria and a greater number of constraints to the problem, is proposed in future research. Acknowledgements: To the High-Performance Computing Center (CECAD - Centro de computación de Alto Desempeño) of Universidad Distrital Francisco José de Caldas for their support, as well as for providing us with a virtual machine to run the proposed mathematical model, which was an essential element in the results obtained.

An Augmented Variable Neighborhood Search to Solve the Capacitated Location-Routing Problem

2021 ◽  
Vol 6 (4) ◽  
pp. 67-76
Author(s):  
Alireza Mohamadi-Shad ◽  
Hamed Niakan ◽  
Hasan Manzour
Keyword(s):  
Variable Neighborhood Search ◽  
Computational Time ◽  
Neighborhood Search ◽  
Future Research ◽  
Setup Cost ◽  
Location Routing Problem ◽  
Routing Problem ◽  
Acceptance Criterion ◽  
Local Searches ◽  
Location Routing

In this paper we proposed a new variable neighborhood search (VNS) for solving the location- routing problem with considering capacitated depots and vehicles. A set of capacitated vehicles, a set of depots with restricted capacities, and associated opening costs, and a set of customers with deterministic demands are given. The problem aims to determine the depots to be opened, fleet assignment to each depot, and the routes to be performed to satisfy the demand of the customers. The objective is to minimize the total costs of the open depots, the setup cost associated with the used vehicles, and transportation cost. We proposed a new VNS which is augmented with a probabilistic acceptance criterion as well as a set of efficient local searches. The computational results implemented on four well-known data sets demonstrate that the proposed algorithm is competitive with other well- known algorithms while reaching many best-known solutions and updating six best new results with reasonable computational time. Conclusions and future research avenues close the paper.

scholarly journals Cyberstalking Victimization Model Using Criminological Theory: A Systematic Literature Review, Taxonomies, Applications, Tools, and Validations

Electronics ◽  
2021 ◽  
Vol 10 (14) ◽  
pp. 1670
Author(s):  
Waheeb Abu-Ulbeh ◽  
Maryam Altalhi ◽  
Laith Abualigah ◽  
Abdulwahab Ali Almazroi ◽  
Putra Sumari ◽  
...  
Keyword(s):  
Data Analysis ◽  
Structural Equation ◽  
Large Scale ◽  
Review Paper ◽  
Essential Element ◽  
Routine Activities ◽  
Criminological Theory ◽  
Equation Modeling ◽  
Future Research ◽  
Proposed Model

Cyberstalking is a growing anti-social problem being transformed on a large scale and in various forms. Cyberstalking detection has become increasingly popular in recent years and has technically been investigated by many researchers. However, cyberstalking victimization, an essential part of cyberstalking, has empirically received less attention from the paper community. This paper attempts to address this gap and develop a model to understand and estimate the prevalence of cyberstalking victimization. The model of this paper is produced using routine activities and lifestyle exposure theories and includes eight hypotheses. The data of this paper is collected from the 757 respondents in Jordanian universities. This review paper utilizes a quantitative approach and uses structural equation modeling for data analysis. The results revealed a modest prevalence range is more dependent on the cyberstalking type. The results also indicated that proximity to motivated offenders, suitable targets, and digital guardians significantly influences cyberstalking victimization. The outcome from moderation hypothesis testing demonstrated that age and residence have a significant effect on cyberstalking victimization. The proposed model is an essential element for assessing cyberstalking victimization among societies, which provides a valuable understanding of the prevalence of cyberstalking victimization. This can assist the researchers and practitioners for future research in the context of cyberstalking victimization.

scholarly journals A Mathematical Problem for Security Analysis of Hash Functions and Pseudorandom Generators

2015 ◽  
Vol 26 (02) ◽  
pp. 169-194 ◽  
Author(s):  
Koji Nuida ◽  
Takuro Abe ◽  
Shizuo Kaji ◽  
Toshiaki Maeno ◽  
Yasuhide Numata
Keyword(s):  
Mathematical Problem ◽  
Security Analysis ◽  
Hash Functions ◽  
Future Research ◽  
Theoretical Frameworks ◽  
Pseudorandom Generators ◽  
Mathematical Problems ◽  
Security Evaluations ◽  
Security Property ◽  
Provably Secure

In this paper, we specify a class of mathematical problems, which we refer to as “Function Density Problems” (FDPs, in short), and point out novel connections of FDPs to the following two cryptographic topics; theoretical security evaluations of keyless hash functions (such as SHA-1), and constructions of provably secure pseudorandom generators (PRGs) with some enhanced security property introduced by Dubrov and Ishai (STOC 2006). Our argument aims at proposing new theoretical frameworks for these topics (especially for the former) based on FDPs, rather than providing some concrete and practical results on the topics. We also give some examples of mathematical discussions on FDPs, which would be of independent interest from mathematical viewpoints. Finally, we discuss possible directions of future research on other crypto-graphic applications of FDPs and on mathematical studies on FDPs themselves.

Teaching Personal Finance Mathematical Problem Solving to Individuals With Moderate Intellectual Disability

2016 ◽  
Vol 40 (1) ◽  
pp. 5-14 ◽  
Author(s):  
Jenny Root ◽  
Alicia Saunders ◽  
Fred Spooner ◽  
Chelsi Brosh
Keyword(s):  
Problem Solving ◽  
Mathematical Problem ◽  
Functional Relation ◽  
Personal Finance ◽  
Future Research ◽  
School Students ◽  
Problem Solving Skills ◽  
Mathematical Problems ◽  
Based Instruction ◽  
Multiple Probe

The ability to solve mathematical problems related to purchasing and personal finance is important in promoting skill generalization and increasing independence for individuals with moderate intellectual disabilities (IDs). Using a multiple probe across participant design, this study investigated the effects of modified schema-based instruction (MSBI) on personal finance problem solving skills, purchasing an item on sale or leaving a tip, and using a calculator or iDevice (i.e., iPhone or iPad) for three middle school students diagnosed with a moderate ID. The results showed a functional relation between MSBI using a calculator on the participant’s ability to solve addition and subtraction personal finance word problems and generalize to iDevices. The findings of this study provide several implications for practice and offer suggestions for future research.

Endothelial progenitor cells and hypertension: current concepts and future implications

2016 ◽  
Vol 130 (22) ◽  
pp. 2029-2042 ◽  
Author(s):  
Shengyuan Luo ◽  
Wenhao Xia ◽  
Cong Chen ◽  
Eric A. Robinson ◽  
Jun Tao
Keyword(s):  
Progenitor Cells ◽  
Endothelial Progenitor Cells ◽  
Current Knowledge ◽  
Circulatory System ◽  
Essential Element ◽  
Future Research ◽  
Chronic Hypertension ◽  
Vascular Endothelial ◽  
Endothelial Progenitor ◽  
Endothelial Integrity

The discovery of endothelial progenitor cells (EPCs), a group of cells that play important roles in angiogenesis and the maintenance of vascular endothelial integrity, has led to considerable improvements in our understanding of the circulatory system and the regulatory mechanisms of vascular homoeostasis. Despite lingering disputes over where EPCs actually originate and how they facilitate angiogenesis, extensive research in the past decade has brought about significant advancements in this field of research, establishing EPCs as an essential element in the pathogenesis of various diseases. EPC and hypertensive disorders, especially essential hypertension (EH, also known as primary hypertension), represent one of the most appealing branches in this area of research. Chronic hypertension remains a major threat to public health, and the exact pathologic mechanisms of EH have never been fully elucidated. Is there a relationship between EPC and hypertension? If so, what is the nature of such relationship–is it mediated by blood pressure alterations, or other factors that lie in between? How can our current knowledge about EPCs be utilized to advance the prevention and clinical management of hypertension? In this review, we set out to answer these questions by summarizing the current concepts about EPC pathophysiology in the context of hypertension, while attempting to point out directions for future research on this subject.

scholarly journals Optimization of medical waste routing problem: The case of TRB1 region in Turkey

2019 ◽  
Vol 9 (2) ◽  
pp. 197-207
Author(s):  
Suleyman Mete ◽  
Faruk Serin
Keyword(s):  
Environmental Sustainability ◽  
Fundamental Problem ◽  
Medical Waste ◽  
Future Research ◽  
Risk Of Infection ◽  
Routing Problem ◽  
Solution Approach ◽  
Potential Risks ◽  
Health Institutions

A fundamental problem concerning medical waste disposal is the evaluation of the real and potential risks arising from waste with the focus on the risk of infection. Therefore, the optimization of medical waste routing from collection to disposal center can minimize the risk of infection. The routing of medical waste considers significant to determine potential routes and select the route with minimum distance. The management of the medical waste is important decision for environmental sustainability and includes the collection, transportation and disposal of these materials. In this paper, a geographic information system (GIS) solution approach is proposed to determine the best location of disposal center. Proposed approach is applied to medical waste transportation between 167 health institutions (collection centers) and predetermined 5 disposal centers through TRB1 region in Turkey, which consist of Malatya, Elaz??, Bingöl and Tunceli provinces. The results of case study are examined and suggestions for future research are provided.

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