Emergency Medical Service Ambulance System Planning: History and Models

Integer linear programming models that incorporate probabilistic and stochastic components represent one approach for capturing the stochastic nature of emergency medical service ambulance systems. This includes modeling non-deterministic call arrival and servicing rates and congestion in the ambulance network (i.e., ambulance unavailability). These models focus on maximizing the total population that can find an available ambulance within a set service time standard (s) with a probability of at least α%. In MALP the concept of local vehicle busyness estimates is introduced to estimate the availability of service in a neighborhood given the neighborhood’s level of demand and the number of ambulance vehicles located in the neighborhood. QMALP is an extension of MALP where queue-theory derived parameters are implemented in the MALP model framework in order to relax the assumption that the probability of different ambulances being busy are independent. Despite this considerable development, several concerns remained about MALP and QMALP, namely the districting assumption where its assumed that a neighborhood’s calls for service are served only by an ambulance in the area, that ambulances in a neighborhood only serve calls for service originating within the neighborhood, or that at least the flow of ambulance service to and from external neighborhoods was roughly equal. Questions have been raised about the validity of MALP and QMALP’s reliability estimates, that is, whether a neighborhood actually received α-reliable service.To address these issues, we developed the Resource-Constrained Queue-based Maximum Availability Location Problem (RC-QMALP). This model is based on a location-allocation framework that (1) assigns workload from neighborhoods to ambulances located within s and ambulance idle capacity to neighborhoods and (2) includes additional constraints designed to help ensure the validity of the original MALP and QMALP constraints used to establish whether a neighborhood can find an available ambulance with α-reliability. We also implemented a secondary minsum objective that minimizes the average travel distance between ambulances and the neighborhoods they service while maintaining the priority of the MALP and QMALP coverage objective.In this thesis, we validated RC-QMALP by comparing the reliable coverage levels predicted by the RC-QMALP to the ambulance system simulations that used the locational configurations suggested by the RC-QMALP. We found that MALP 2 and QMALP provided higher levels of reliable coverage and that RC-QMALP’s secondary objective has a negligible impact on system performance. However, RC-QMALP-based models provide more accurate estimates of reliable coverage and location solutions whose simulated reliable coverage performance was always within 5% of the optimal solution with the same system parameters (we tested 1,080 different model configurations). Our work suggests that (1) simulation models must be developed to handle the modeling assumptions that underlie location optimization models and that (2) service reliability location models should consider additional factors such as ambulance workloads (and their distribution)

A computational study of the Firefighter Problem on graphs

Orientadores: Cid Carvalho de Souza, Pedro Jussieu de RezendeDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: O Problema do Brigadista em Grafos (FFP do inglês The Firefighter Problem é um modelo determinístico e em tempo discreto para simular a propagação e contenção de incêndios em grafos. Ele pode ser descrito da seguinte forma. Na entrada, é dado um inteiro D representando a quantidade de brigadistas disponíveis, um grafo não direcionado e não ponderado G = (V,E) e um subconjunto de vértices B de V, os focos de incêndio. Então, inicia-se nos elementos de B um processo iterativo de propagação e contenção de fogo através dos vértices de G, em rodadas discretas, o qual termina quando não existem mais vértices que possam ser queimados, ou seja, quando o fogo está contido. O objetivo ao resolver o FFP é maximizar o número de vértices não queimados quando o fogo é contido, com a restrição de que no máximo D vértices podem ser protegidos contra o fogo por rodada. Aplicações práticas do FFP, além da obtenção de estratégias para minimização de danos causados por incêndios, podem ser encontradas em áreas como controle de doenças e segurança em redes. O FFP é NP-difícil e métodos heurísticos para lidar com o problema foram relatados previamente na literatura. Nessa dissertação, primeiramente, apresentamos melhorias feitas na primeira formulação PLI proposta para o FFP através de técnicas de preprocessamento e agregação de restrições. Em seguida, descrevemos novas heurísticas gulosas e introduzimos uma nova matheurística para o FFP, uma abordagem que se baseia na interoperação entre meta-heurísticas e programação matemática. Experimentos foram conduzidos em um benchmark público tanto para configuração de parâmetros quanto para análise de desempenho, através de comparação dos resultados obtidos com aqueles publicados anteriormente. Com respeito às modificações no modelo PLI, um speedup de aproximadamente 2 em média foi alcançado. Observamos que as modificações feitas podem levar a geração de soluções infactíveis, mas conseguimos demonstrar que é possível tornar tais soluções factíveis em tempo polinomial. Em referência às heurísticas, essas foram executadas seguindo uma metodologia para construir uma solução na qual escolhas gulosas aleatorizadas são realizadas para selecionar quais vértices serão defendidos, de acordo com conceitos introduzidos na meta-heurística GRASP. Comparando essas heurísticas com as que foram propostas por trabalhos anteriores, observamos que duas das nossas estão entre as cinco melhores na maioria dos casos. Com relação à matheurística, através de uma análise estatística rigorosa, verificamos que existe diferença estatisticamente significativa entre nossa estratégia e as demais, ao mesmo tempo que nossa matheurística conseguiu resultados melhores na maioria das instânciasAbstract: The firefighter problem (FFP) is a deterministic discrete-time model for the spread and containment of fire on a graph. Such problem is described as follows. As its inputs, there is an integer D representing the number of available firefighters, an undirected and unweighted graph G=(V, E) and a subset of vertices B of V, the fire outbreaks. Then, an iterative process of fire propagation and containment through the vertices of G is started at the ones from B. This process ends when there are no more vertices to be burnt, that is, the fire is contained. The goal when solving the FFP is to maximize the number of vertices that are not burned when the fire is contained, with the constraint that at most D vertices can be protected against the fire per iteration. Practical applications of the FFP, besides obtaining strategies to minimize the damage caused by fire, can be found in areas such as disease control and network security. The FFP is NP-hard and heuristic methods to tackle the problem were proposed earlier in the literature. In this dissertation, firstly we present modifications made on the first ILP model proposed to the FFP through techniques of preprocessing and constraint aggregation. Moreover, we describe new greedy heuristics and also we introduce a novel matheuristic to the FFP, an approach based on the interoperation between metaheuristics and mathematical programming. A series of computational experiments were conducted on a public benchmark both for parameter tuning and to compare our results with those obtained previously. In respect to the modifications on the ILP model, a speedup of 2 in average was obtained. While constraint aggregation can lead to infeasible solutions, we prove that the latter can be converted to feasible ones in linear time. Regarding the heuristics, they were executed following a methodology to construct a solution in which greedy randomized choices are made to select which vertices should be defended, according to concepts introduced by the GRASP metaheuristic. Comparing these heuristics with the ones proposed by previous works, we observe that two of ours are between the five best ones in general. In relation to the matheuristic, through rigorous statistical analysis, we were able to verify that there is a statistically significant difference between our strategy and the remaining ones, while our matheuristic had better results on the majority of the instancesMestradoCiência da ComputaçãoMestre em Ciência da Computação133728/2016-1CNP

Wildfire Hazard and Risk Assessment

Wildfire risk can be perceived as the combination of wildfire hazards (often described by likelihood and intensity) with the susceptibility of people, property, or other valued resources to that hazard. Reflecting the seriousness of wildfire risk to communities around the world, substantial resources are devoted to assessing wildfire hazards and risks. Wildfire hazard and risk assessments are conducted at a wide range of scales, from localized to nationwide, and are often intended to communicate and support decision making about risks, including the prioritization of scarce resources. Improvements in the underlying science of wildfire hazard and risk assessment and in the development, communication, and application of these assessments support effective decisions made on all aspects of societal adaptations to wildfire, including decisions about the prevention, mitigation, and suppression of wildfire risks. To support such efforts, this Special Issue of the journal Fire compiles articles on the understanding, modeling, and addressing of wildfire risks to homes, water resources, firefighters, and landscapes

Advances on Mechanics, Design Engineering and Manufacturing III

This open access book gathers contributions presented at the International Joint Conference on Mechanics, Design Engineering and Advanced Manufacturing (JCM 2020), held as a web conference on June 2–4, 2020. It reports on cutting-edge topics in product design and manufacturing, such as industrial methods for integrated product and process design; innovative design; and computer-aided design. Further topics covered include virtual simulation and reverse engineering; additive manufacturing; product manufacturing; engineering methods in medicine and education; representation techniques; and nautical, aeronautics and aerospace design and modeling. The book is organized into four main parts, reflecting the focus and primary themes of the conference. The contributions presented here not only provide researchers, engineers and experts in a range of industrial engineering subfields with extensive information to support their daily work; they are also intended to stimulate new research directions, advanced applications of the methods discussed and future interdisciplinary collaborations

Wireless Sensor Networks

The aim of this book is to present few important issues of WSNs, from the application, design and technology points of view. The book highlights power efficient design issues related to wireless sensor networks, the existing WSN applications, and discusses the research efforts being undertaken in this field which put the reader in good pace to be able to understand more advanced research and make a contribution in this field for themselves. It is believed that this book serves as a comprehensive reference for graduate and undergraduate senior students who seek to learn latest development in wireless sensor networks

Computer science: the hardware software and heart of IT

1st edition, 201