Angel Ruiz

• Professor (Full) at Université Laval

Most of the time in a distribution system, depot location and vehicle routing are interdependent, and recent studies have shown that the overall system cost may be excessive if routing decisions are ignored when locating depots. The location-routing problem (LRP) overcomes this drawback by simultaneously tackling location and routing decisions. Thi...

Balancing assembly lines is a crucial task for manufacturing companies in order to improve productivity and min- imize production costs. Despite some progress in exact methods to solve large scale problems, softwares implementing simple heuristics are still the most commonly used tools in industry. Some metaheuristics have also been proposed and sh...

Approximately 755 million cases and 7 million deaths have been reported since the COVID‐19 pandemic. Based on the availability of vaccines to contain the spread of COVID‐19, various vaccination plans have been implemented globally, some more effective than others, depending on each country's social, territorial, economic, and political circumstance...

Humanitarian logistics face significant challenges during natural disasters due to operational uncertainties. Humanitarian logistics networks such as food banks must manage both regular operations and disaster-induced supply and demand. The study aims to develop and assess two-stage stochastic models that support decision-making under these dual op...

This paper addresses the management of patients’ transportation requests within a hospital, a very challenging problem where requests must be scheduled among the available porters so that patients arrive at their destination timely and the resources invested in patient transport are kept as low as possible. Transportation requests arrive during the...

Purpose: This study aims to address the pressing need for accurate forecasting of healthcare resource demands during the COVID-19 pandemic. It presents a novel approach that combines a stochastic Markov model and a discrete event simulation model to dynamically predict hospital admissions and daily occupancy of hospital and ICU beds.Design/methodol...

COVID-19 pandemic has sent millions of people to hospitals worldwide, exhausting on many occasions the capacity of healthcare systems to provide care patients required to survive. Although several epidemiological research works have contributed a variety of models and approaches to anticipate the pandemic spread, very few have tried to translate th...

This article is part of the Research Topic ‘Health Systems Recovery in the Context of COVID-19 and Protracted Conflict' Introduction Hospital managers address elective patient surgical backlogs with different strategies: increasing installed capacity, managing demand and improving efficiency. Recently, and particularly since the COVID-19 elective...

Background The coronavirus disease 2019 pandemic has prompted the exploration of new response strategies for such health contingencies in the near future. Over the last 15 years, several pharmacy-based immunization (PBI) strategies have emerged seeking to exploit the potential of pharmacies as immunization, medication sale, and rapid test centers....

Purpose Food banks play an increasingly important role in society by mitigating hunger and helping needy people; however, research aimed at improving food bank operations is limited. Design/methodology/approach This systematic review used Web of Science and Scopus as search engines, which are extensive databases in Operations Research and Manageme...

The growing interest in sustainability has pushed governments to elaborate new legislations and orientations and, in turn, has led companies and organizations to consider sustainability goals in their strategies, operations management, and decision-making processes. This is the case in natural resources supply chains, and particularly in forest pro...

Background The COVID-19 pandemic has put tremendous pressure on hospital resources around the world. Forecasting demand for healthcare services is important generally, but crucial in epidemic contexts, both to facilitate resource planning and to inform situational awareness. There is abundant research on methods for predicting the spread of COVID-1...

Foodbank networks provide adequate infrastructure and perform logistics activities to supply food to people in need on a day-to-day basis. However, in the case of a sudden event, such as a natural disaster, they must reconfigure themselves to quickly and fairly satisfy the needs of the affected people, despite the rapid changes in supply and demand...

In the aftermath of a natural disaster, humanitarian aid must be delivered as fast as possible to the affected population to alleviate human suffering and minimize deaths. To this end, humanitarian logistics managers must design an adequate supply chain and organize complex logistic activities. Considerable research efforts have been devoted to ela...

Objective Identifying effective strategies to reduce waiting times is a crucial issue in many areas of health services. Long waiting times for rehabilitation services have been associated with numerous adverse effects in people with disabilities. The main objective of this study was to conduct a systematic literature review to assess the effectiven...

Emergency Medical Services (EMS) first mission is to reach people requiring urgent medical attention and transport them to hospitals or care facilities. In many cases, EMS also provide a second mission, which concerns the non-emergency transportation of patients. These services have different characteristics and goals from a managerial standpoint a...

p class="Abstract">This paper presents the generation of a plausible data set related to the needs of COVID-19 patients with severe or critical symptoms. Possible illness’ stages were proposed within the context of medical knowledge as of January 2021. The parameters chosen in this data set were customized to fit the population data of the Valencia...

To increase fairness and equity in access to rehabilitation services, a strategy emerging from the literature is patient prioritization. Selecting explicit prioritization criteria is a complex task because it is important to simultaneously consider the objectives of all stakeholders. The of this study was to compare service users’ and service provi...

During the last 20 years the climate-related disasters have dominated the picture accounting for 91% of all 7255 recorded events, being the floods the most frequent type of disaster. Several decisions, such as the allocation of shelters and relief distribution, are made to minimize the aftermath impact on the population. In this chapter, we present...

Introduction and aims: Prioritization tools aim to manage access to care by ranking patients equitably in waiting lists based on determined criteria. Patient prioritization has been studied in a wide variety of clinical health services, including rehabilitation contexts. We created a web-based patient prioritization tool (PPT) with the participati...

Careful planning of an ambulance service is critical to reduce response times to emergency calls and make assistance more effective. However, the demand for emergency services is highly variable, and good prediction of the number of future emergency calls, and their spatial and temporal distribution, is challenging. In this work, we propose a Bayes...

This paper presents an integrated framework for capacity and operations planning in Spanish sheltered employment centers (SECs). Employment provides socio-economic opportunities for people with disability. Well functioning SECs that provide opportunities for people with and without disability to work alongside each other are an important component...

Background Patient prioritization is a strategy used to manage access to healthcare services. Patient prioritization tools (PPT) contribute to supporting the prioritization decision process, and to its transparency and fairness. Patient prioritization tools can take various forms and are highly dependent on the particular context of application. Co...

This paper describes the redesign of the internal logistics of an industrial assembly facility. In particular, we are concerned by the management of components and parts’ flow to feed the different workstations of the production line. This flow of components starts at the reception docks where suppliers’ trucks arrive. Components unloaded from truc...

Order-up-to level is one of the most popular inventory management strategies in the retail industry. However, there exist several manners to fix the up-to-level. In this paper, we consider several of these manners and analyze their application to a real retail company. The company requires a method which is simple to understand and adopt and that s...

Production environments vastly vary in the industrial reality and can also do so with time. To manage production as optimally as possible, having tools that guide the people in charge of production would greatly help to know the best approach to take to perform the task according to the factory’s production typology. These tools should also be able...

Purpose: A large number of people living with a chronic disability wait a long time to access publicly funded rehabilitation services such as Augmentative and Alternative Communication (AAC) services, and there is no standardized tool to prioritize these patients. We aimed to develop a prioritization tool to improve the organization and access to t...

Introduction. Prioritization tools aim to manage access to care by ranking patients equitably in waiting list based on determined criteria. Patient prioritization has been studied in a wide variety of clinical health services, including rehabilitation contexts. We created a web-based patient prioritization tool with the participation of stakeholder...

Background: Patient prioritization is a strategy used to manage access to healthcare services. Patient prioritization tools (PPT) contribute to supporting the prioritization decision process, and to its transparency and fairness. Patient prioritization tools can take various forms and are highly dependent on the particular context of application. C...

Background. Patient prioritization is a strategy used to manage access to healthcare services. Patient prioritization tools (PPT) contribute to supporting the prioritization decision process, and to its transparency and fairness. Patient prioritization tools can take various forms and are highly dependent on the particular context of application. C...

Purpose: With this work, we intend to promote research on the application of Operations Management tools in order to assist with decision-making in health crisis situations. During the first six weeks of the COVID-19 crisis in Spain, we have contacted a large number of hospital and health department managers in the Valencian Community and other reg...

This paper addresses the multi-period ambulance redeployment planning problem in a two-tiered Emergency Medical System (EMS) where two types of ambulances are used to respond to two categories of emergency calls. In order to account for the uncertainty inherent to both categories of demand, we propose a two-stage stochastic programming model that a...

This study addresses the Ambulance Location and Dispatching Problem (ALDP), which jointly determines the location of available ambulances and their dispatching policy. The latter takes the form of a dispatching list that defines, for each zone of the covered territory, an ordered list providing a hierarchy of ambulances to be chosen whenever a call...

This paper addresses the redesign of an industrial assembly facility’s internal logistics. To this end, it proposes a mathematical formulation that optimizes the components and parts’ flow to feed the different workstations of the production lines. This flow of components starts at the reception docks where suppliers’ trucks arrive. Components unlo...

This article addresses a new version of the biomedical sample transportation problem, as a vehicle routing problem with precedence constraints arising in the context of healthcare logistics, and proposes an iterated local search algorithm to solve it. This new version is more realistic and complex since it considers the collection centres’ opening...

This paper describes the modeling efforts devoted by the Ministry of Health and Social Services of Québec, Canada (MSSS), to ensure the long-term bearability of their care system. To this end, it studies the relationships between four entities that self-regulate and interact to form the complex care-providing system: (1) universities; (2) hospitals...

This paper proposes an integrated approach to merge patient prioritization and patient scheduling to improve access to services in an elective (i.e., non-urgent) context. In particular, we assume that patients are included on a waiting list for a given surgery, and that every patient on the list has received a “utility score”, which is a proxy for...

This paper explores how the consideration of two important practical aspects related to transportation in the forestry industry, wood moisture content and seasonal limitations on the maximal truck’s payload, may lead to savings in procurement costs. To this end, it proposes a multi-period mathematical formu- lation that decides on the location of p...

This paper describes a variant of the Periodic Capacitated Arc Routing Problem for inspections in a railroad network. Inspections are performed by vehicles over a time horizon on which some stretches need evaluation more frequently than others due to its use. Each car can evaluate one stretch per day without being attached to a depot; at each day,...

Purpose: The purpose of this paper is to define a clinical pathway for total joint replacement (TJR) surgery, estimate the effect of delays between steps of the pathway on wait time for surgery and to identify factors contributing to more efficient operations and challenges to their implementation. Design/methodology/approach: This is a case stu...

BACKGROUND Queueing patients on waiting lists is a common practice to manage access to rehabilitation services. To increase fairness and equity in access, a strategy emerging from the literature is patient prioritization. The goal is for patients with the greatest needs to be treated first and for patient wait times to be determined objectively on...

Background: Waiting lists should be managed as fairly as possible to ensure that patients with greater or more urgent needs receive services first. Patient prioritization refers to the process of ranking referrals in a certain order based on various criteria with the aim of improving fairness and equity in the delivery of care. Despite the widespr...

This paper considers a dynamic scheduling problem where the set of jobs to perform is modified by the arrival of events (customer orders) requiring the execution of a new job or the cancellation of a previously ordered one once the production has begun. To tackle this dynamic context, we propose an online approach that reconsiders the actual schedu...

This paper deals with a dynamic scheduling problem where a production schedule must be adapted to cope with the arrival of new orders. The problem encompasses several identical parallel machines with sequence-dependent setup times and a release date for each job. The problem’s goal is to minimize both the makespan and the total tardiness of the job...

This article is inspired by some of the challenges faced by non-governmental organizations in the distribution of humanitarian relief to vulnerable rural communities. A major concern of these organizations is to warrant that relief is distributed in an impartial and transparent way, which gives rise to the notion of fairness. This article thus disc...

Emergency medical services (EMS) systems provide out-of-hospital acute medical care and transportation to the appropriate health care provider to patients with illnesses and injuries. The objective of EMS systems is to satisfy demand requests by providing timely first care medical assistance to patients at the incident scene. This paper aims at des...

Over the past 10 years, a considerable amount of research has been devoted to the development of models to support decision making in the particular yet important context of Emergency Medical Services (EMS). More specifically, the need for advanced strategies to take into account the uncertainty and dynamism inherent to EMS, as well as the pertinen...

Biomedical tests play a crucial role in helping physicians to make accurate diagnoses. To perform these tests, thousands of samples are daily transported from several healthcare facilities, where they are collected from patients, to laboratories, where they are analyzed. We consider the challenging Biomedical Sample Transportation Problem (BSTP), w...

Emergency Medical Services (EMS) are responsible of providing medical assistance to any person who requires it in case of emergency, with the main goal of reducing the response time. To do so, several management strategies have been proposed, e.g., districting and preassigned dispatching lists. However, districts are often a priori defined at the s...

Purpose: This study proposes a methodology that translates multiple humanitarian supply chain stakeholders’ preferences from qualitative to quantitative values, enabling these preferences to be integrated into optimization models to ensure their balanced and simultaneous implementation during the decision-making process. Design/methodology/approac...

Analysing risk of today’s complex systems is challenging due to the complex and dynamic nature of systems. The current risk analysis tools are not able to take the complex interactions among risks into account and therefore they can’t predict the behaviour of risks accurately. In an attempt to overcome this shortcoming, this paper proposes an integ...

Emergency Medical Services (EMS) systems aim to provide immediate care in case of emergency. A careful planning is a major prerequisite for the success of an EMS system, in particular to reduce the response time. Unfortunately, the demand for emergency services is highly variable and uncertainty should not be neglected while planning the activities...

Several types of transportation are required daily to support medical activities and services to the patient at a hospital. Intrahospital transportation activities range from transporting inpatients with limited mobility from one location to another to moving samples from one care unit to the hospital laboratory. In practice, patient and material t...

This paper models and formulates an extension to the biomedical sample transportation problem (BSTP), a challenging vehicle routing problem arising in the context of healthcare logistics, and proposes an efficient iterated local search heuristic (ILS) to solve it. In this new and more realistic version of the BSTP, the opening hours of the collecti...

Emergency Medical Service (EMS) systems aim at providing immediate medical care in case of emergency. A careful planning is a major prerequisite for the success of an EMS system, in particular to reduce the response time to emergency calls. Unfortunately, the demand for emergency services is highly variable and uncertainty should not be neglected w...

Despite recent advances in both heuristic and implicit enumeration methods, exploring the whole solution space for large scaled problems remains, in most of practical cases, intractable. Indeed, enumeration and heuristic methods share their ability to thoroughly explore limited regions of the solution space. However, for different reasons they both...

This paper proposes an advanced decision support tool using Fuzzy Cognitive Maps (FCMs) for risk assessment of complex and dynamic systems. The proposed tool is able to predict the impact of each risk on the rest of the risks more accurately by considering uncertainties and also taking into account the complex dependencies among risk factors. This...

There is high level of risks and failures in radiation therapy delivery system for many reasons. These small failures in the system may cause major harms. Radiology failure mode and effect analysis (R-FMEA) is a qualitative risk assessment tool to proactively identify risks that threaten patients in a healthcare process. The main purpose of R-FMEA...

The transportation of biomedical samples is a key component of healthcare supply chains. The samples are collected, consolidated into cooler boxes, and then transported to be analyzed in a specialized laboratory. Since many hospitals and samples' collection points are assigned to the same laboratory, it is important to manage the flow of samples ar...

As a bioterrorist anthrax attack has serious consequences, an emergency management plan that can reduce the number of casualties should be studied. However, the papers studying this area are still few. This paper proposes a model which links the disease progression, the related medical intervention actions and the logistics deployment together to h...

Due to limited healthcare resources for updating CPGs, the substantial cost of updating, and on-going advances and new evidences in healthcare, every institution faces the challenge of CPGs’ prioritization for updating. However, there is no validated criteria or comprehensive process for prioritization of updating CPGs in literature. Therefore, the...

In order to ensure an adequate service to the population, Emergency Medical Services (EMS) rely on a given number of ambulances strategically located over the territory they serve. The arrival of calls to EMS being highly uncertain and dynamic, it may happen that at some point, the vehicles available to respond to these calls no longer cover proper...

Once elective patients have been referred to surgery, they are is put in a waiting list until they can be scheduled according to their particular condition and the time they have spent in the list. Waiting lists are often managed in a rather informal and unstructured manner, leading to a lack of robustness and homogeneity in the assessing of the re...

Outbreak of diseases can lead to a great number of deaths. Therefore, the establishment of an effective disease prevention and control plan, which can decrease the number of deaths, is of paramount importance. This paper critically reviews literatures focusing on disease prevention and control plans and proposes the directions for the future resear...

This paper presents a systematic literature review on sustainable supply chain design and planning models in the field of Operations Research (OR). The goal is to analyse to which extent economic, environmental and social aspects are integrated into mathematical models. The focus is drawn on sustainahility performance criteria considered, and the w...

The Canadian forestry industry plays an important role for the country's economy. In order to overcome economic challenges, and continue evolving its results, the rational use of resources in forestry products supply chain is required. We propose in this paper a mixed integer programming model describing the wood fibre network procurement of the su...

As an infectious disease has serious consequences and demands medical resources suddenly, an emergency management plan which can reduce the number of deaths should be studied. However, the papers in this area are still few and no paper proposes a model which can be adapted to general infectious diseases. This paper proposes a model which links the...

In this paper, we solve the Vehicle Routing Problem with Lunch Break (VRPLB), which arises when drivers must take pauses during their shift, for example, for lunch breaks. Driver breaks have already been considered in long haul transportation when drivers must rest during their travel, but the underlying optimization problem remains difficult and f...

This paper models a humanitarian aid distribution problem, which aims to satisfy the basic needs of a population in the aftermath of a natural or man-made disaster. The model considers dispatching goods from local distribution centers to distribution points during a given time horizon covering several periods (days). It takes into account practical...

This paper proposes a hybrid algorithm to tackle a real-world problem arising in the context of pulp and paper production. This situation is modelled as a production problem where one has to decide which wood will be used by each available processing unit (wood cooker) in order to minimize the variance of wood densities within each cooker for each...

Collaborative networks are complex systems and consist of many factors with dependencies among them. Although the number of collaborative networks such as advanced supply chains or virtual organizations/laboratories/ e-science is growing and their significance is increasing in the world, many of them are unsuccessful. In addition, very little atten...

Maintenance outsourcing is a common practice in many industries, such as aviation and medical equipment manufacturing. However, there is always some dynamic risks associated with outsourcing. Risk analysis of maintenance outsourcing projects is a complex task due to consisting of many risk factors with dependencies among them. Although there are so...

This paper proposes an integrated approach to identify, evaluate, and improve the potential failures in a service setting. In this paper a new integrated approach is developed to improve the method of Service Failure Mode Effects and Critically Analysis (FMEA) from an economic perspective. The contribution of this paper is that it combines a fuzzy...

Enterprise resource planning (ERP) projects are very complex tasks, expensive, time-consuming, and risky investments. One of the main reasons for the high ERP project failure rate is that managers don't assess and manage the risks involved in these projects. In addition, they don't know the importance degree for each of these risks. On the other ha...

Emergency medical services (EMS) are dedicated to provide urgent medical care to any person requiring it and to ensure their transport to a hospital or care facility, if required. Moreover, in many contexts, EMS also have to provide transportation services for patients need to go from one hospital to another or between their home and the hospital....