Romero-Silva, Rodrigo
Thumbnail Image
Preferred name
Romero-Silva, Rodrigo
Official Name
Romero Silva, Rodrigo
Alternative Name
rromeros
Main Affiliation

Research Output

Filters
20
19 1
Reset filters

Settings
Now showing 1 - 10 of 20
No Thumbnail Available
Publication

Performance of merging lines with uneven buffer capacity allocation: the effects of unreliability under different inventory-related costs

2020 , Shaaban, Sabry , Romero-Silva, Rodrigo

This simulation study investigates whether machine efficiency, mean time to failure (MTTF) and mean time to repair (MTTR) significantly affect the performance of uneven buffer capacity allocation patterns for merging lines. Also studied is the trade-off between increasing throughput via bigger buffers and their associated inventory-related costs, since previous studies have shown that higher overall buffer capacity and higher average inventory content result in higher throughput. Results suggest that an ascending buffer allocation pattern (concentrating buffer capacity towards the end of the line) produces higher throughput in shorter, more unreliable lines; whereas the balanced pattern shows better performance in longer, more reliable lines. Increasing average buffer capacity per station and/or having higher average buffer content was found to be more cost-effective in lines with lower machine inefficiency, shorter MTTF and MTTR, and longer lines. Results differed between reliable and unreliable lines since reliable lines were particularly penalised by buffer capacity investiment/maintenance costs due to a relatively low increase in throughput resulting from the addition of extra buffer capacity.

View
No Thumbnail Available
Publication

Trends and topics in IJPR from 1961 to 2017: a statistical history

2018 , Romero-Silva, Rodrigo , Marsillac, Erika

This paper studies the history of the International Journal of Production Research (IJPR) by analysing the topics that have received the most attention in each of the journal’s publication years. Text mining exposed for scrutiny the most frequently mentioned and cited terms contained in the titles, abstracts and keywords of IJPR papers. Analyses suggest that the triad of scheduling/optimisation/simulation and supply-chain-related topics have been IJPR’s mainstays, but valuable opportunities remain for relevant topics that have not yet been concurrently and frequently studied. Results also show that terms related to sustainability and risk management topics have gained recent relevance. In addition, IJPR appears to complement its modelling technique focus with empirical methodological approaches to provide a well-balanced perspective, since the ‘case study’ term is common. Finally, a linear relationship is found between the number of papers that have covered certain topics and the number of citations those topics have received, highlighting which topics had fewer or more citations than expected, given the number of papers that covered those topics. IJPR stands as one of the most prestigious and established journals in its field and the results from this study indicate the evolving interests of the field for over half a century.

View
No Thumbnail Available
Publication

Reducing the variability of inter-departure times of a single-server queueing system : the effects of skewness

2019 , Romero-Silva, Rodrigo , Marsillac, Erika , Shaaban, Sabry , Hurtado-Hernandez, Margarita

A critical performance measure in serial production lines is the variability of inter-departure times of a single-server queue. Increasing upstream inter-departure time variability generates greater downstream variability, diminishing overall line performance. Theory suggests that the variability of inter-departure times of a single-server queue is reduced by decreasing the variance of inter-arrival and service times. This study investigates the effects of the skewness of inter-arrival and service time distributions on the variability of inter-departure times. Contrary to previous results suggesting that mean waiting times of a GI/G/1 queue can be reduced by increasing inter-arrival time skewness, this experimental study of a GI/G/1 queue with triangular inter-arrival and service times shows that the inter-departure time coefficient of variation is reduced through a combination of negative inter-arrival time skewness and positive service time skewness. These results also suggest that the absolute value of the negative autocorrelation between consecutive departures is reduced by the same combination of negative inter-arrival time skewness and positive service time skewness for low values of server's utilization, while positive skewness for both inter-arrival and service times reduces this value for high values of server's utilization. Finally, it was found that queue capacity constraints increase the coefficient of variation of inter-departure times, as has been previously suggested, as well as the skewness and the absolute correlation values of the inter-departure time distribution. © 2019 Elsevier Ltd

View
No Thumbnail Available
Publication

Alineación entre métodos y necesidades de programación de la producción

2016 , Romero-Silva, Rodrigo , Santos García, Javier , Hurtado-Hernandez, Margarita

Este artículo sugiere una alineación entre entornos de producción y metodologías de programación de la producción de acuerdo a las necesidades de programación de cada tipo de entorno de producción. El estudio considera dos tipos de entornos de planificación y, dependiendo de sus necesidades de planificación, propone los métodos que mejor se puedan ajustar para soportar la tarea de la programación de la producción

View
No Thumbnail Available
Publication

Serial production line performance under random variation : dealing with the "law of variability"

2019 , Romero-Silva, Rodrigo , Marsillac, Erika , Shaaban, Sabry , Hurtado-Hernandez, Margarita

Many Queueing Theory and Production Management studies have investigated specific effects of variability on the performance of serial lines since variability has a significant impact on performance. To date, there has been no single summary source of the most relevant research results concerned with variability, particularly as they relate to the need to better understand the ‘Law of Variability’. This paper fills this gap and provides readers the foundational knowledge needed to develop intuition and insights on the complexities of stochastic simple serial lines, and serves as a guide to better understand and manage the effects of variability and design factors related to improving serial production line performance, i.e. throughput, inter-departure time and flow time, under random variation. © 2019 The Society of Manufacturing Engineers

View
No Thumbnail Available
Publication

A conceptual framework of the applicability of production scheduling from a contingency theory approach: addressing the theory-practice gap

2022 , Romero-Silva, Rodrigo , Santos, Javier , Hurtado-Hernandez, Margarita

In the last century, there was a general perception that scheduling theory was highly irrelevant to scheduling practice. Many recent studies, however, have suggested that the applicability of scheduling approaches is highly intertwined with the manufacturing environment in which the scheduling task is carried out. In this paper we used the constructs of Contingency Theory to suggest specific fits between scheduling approaches and manufacturing environments, after suggesting that the theory-practice gap in production scheduling research has been caused by three issues: (a) simplification of scheduling problems, (b) simplification of the practical scheduling task as a decision process, and (c) lack of relevance of the traditional scheduling approach to all manufacturing environments. Furthermore, we suggest that the dynamism of the state of the system and the complexity of the scheduling problem are the two constituting vectors that define the complexity of the scheduling task. We use both vectors to identify different types of manufacturing environments and propose specific fits with scheduling approaches. Finally, we hypothesize that the fit between scheduling approaches and manufacturing environments is only relevant in environments with high resource utilization where the scheduling task could have a bigger impact on a firm’s performance, and present three case studies to better exemplify the relevance of the conceptual framework. ©2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

View
No Thumbnail Available
Publication

The impact of unequal processing time variability on reliable and unreliable merging line performance

2021 , Romero-Silva, Rodrigo , Shaaban, Sabry , Marsillac, Erika , Laarraf, Zouhair

Research on merging lines is expanding as their use grows significantly in the contexts of remanufacturing, reverse logistics and developing economies. This article is the first to study the behavior of unpaced, reliable, and unreliable merging assembly lines that are deliberately unbalanced with respect to their coefficients of variation (CV). Conducting a series of simulation runs with varying line lengths, buffer storage capacities and unbalanced CV patterns delivers intriguing results. For both reliable and unreliable lines, the best pattern for generating higher throughput is found to be a balanced configuration (equal CVs along both parallel lines), except for unreliable lines with a station buffer capacity of six. In that case, the highest throughput results from the descending configuration, i.e. concentrating the variable stations close to the beginning of both parallel lines and the steady stations towards the end of the line. Ordering from the least to most steady station also provides the best average buffer level. By exploring the experimental Pareto Frontier, this study shows the combined performance of unbalanced CV patterns for throughput and average buffer level. Study results suggest that caution should be exercised when assuming equivalent behavior from reliable and unreliable lines, or single serial lines and merging lines, since the relative throughput performance of some CV patterns changed between the different configurations.

View
No Thumbnail Available
Publication

Mapping operations research in project management: a bibliometric analysis

2021 , Muñoz Villamizar, Andrés , Solano Charris, Elyn L. , Romero-Silva, Rodrigo

Successful project management can help organisations in reducing costs and increasing its efficiency. Likewise, operations research has contributed significantly to improve project management performance with phase-project-planning methodologies. However, as far as we know, there is no literature review that compiles operations research in project management (OR+PM). Thus, this paper aims to present a bibliometric analysis of OR+PM using 1,254 research papers retrieved from ISI Web of Science. This final dataset is composed of articles from scientific journals published between 2001-2018. The results indicate that project scheduling, project management and resource-constrained project scheduling have been the backbone concepts of OR+PM; while terms, such as sustainability, earned value management, multi-objective optimisation, and multi-mode resource-constrained project scheduling problem have been gaining relevance in recent years. Results also show who have been the most influential authors, institutions and countries in the development of this field. Finally, future research opportunities for OR+PM are identified.

View
No Thumbnail Available
Publication

Estimation of Quantile Confidence Intervals for Queueing Systems Based on the Bootstrap Methodology

2017 , Romero-Silva, Rodrigo , Hurtado-Hernandez, Margarita

This paper presents a simple methodology for estimating confidence intervals of quantiles in queueing systems. The paper investigates the actual probability density function of quantile estimators resulting of independent replications. Furthermore, we present a methodology, based on the concepts of bootstrapping, i.e., re-sampling and sub-sampling, to calculate the variability of an estimator without running different independent replications. Contrary to what overlapping and non-overlapping batching procedures suggest, we propose to randomly select data points to form a sub-sample, instead of selecting time-consecutive data points. The results of this study suggest that this proposal reduces the correlation between sub-samples (or batches) and overcomes the issue of normality. © 2017, Springer International Publishing AG.

View
No Thumbnail Available
Publication

A framework for studying practical production scheduling

2014 , Romero-Silva, Rodrigo , Santos, Javier , Hurtado-Hernandez, Margarita

The aim of this paper is to present what we believe are the most relevant findings and results regarding practical scheduling in order to define practical production scheduling and create a framework that helps researchers to study the various topics that fall under the umbrella of practical production scheduling and to identify the current state of knowledge for each topic. Studies from different fields were analysed and included in this paper, contributing significant knowledge to build a definition of practical production scheduling. Finally, we discuss the applicability that scheduling, as a task, could have in real companies.

View