The global airline industry: an assessment of the impact of low-cost carriers on the technical efficiency of full-service airlines

Since the emergence of the first low-fare airline, Southwest Airlines, we have witnessed the spread of the low-cost phenomenon in different regions of the world. The simplicity, the low fares and the focus on core business (flying) have been the critical basis for their success, and the concern of traditional operators who see their market positioning threatened. To remain competitive, full-service operators have been forced to redefine their business model. With great interest in the innovative nature of low-cost carriers, literature has covered inter-business model comparisons of efficiency, as well as on the analysis of the strategies carried out by full-service to adapting to the increased competition. However, there seems to be no study on the impact of low-cost operators on the technical efficiency of full-service airlines. Thus, this thesis aims to analyse the impact of the low-cost regional market share on the technical efficiency of full-service airlines domiciled in the same region. In order to pursue this analysis, a two-stage Data Envelopment Analysis was implemented. Initially, bootstrapped efficiency scores were estimated for a set of 137 passenger airlines. Subsequently, the estimated efficiency measures were used as a dependent variable in a truncated bootstrap regression to identify the determinants of the technical efficiency. Results suggest that larger low-cost market shares are associated with lower input uses for the same full-service carriers’ output levels based on that region. This relationship might be explained by the adoption of better management practices that approach the full-service model to the low-cost model.A criação da primeira companhia aérea de baixo-custo, a "Southwest Airlines", impulsionou o desenvolvimento mundial de tantas outras no sector da aviação. A simplicidade, os preços baixos e o foco no principal objetivo da atividade (voar) têm sido a chave do seu sucesso e, simultaneamente, uma ameaça às companhias aéreas tradicionais. Inevitavelmente, os operadores de serviço-completo têm vindo a realizar mudanças no seu modelo de negócio para conseguirem manter-se competitivas. Recentemente, alguns estudos têm-se focado na comparação entre os dois modelos de negócio e na análise das estratégias das transportadoras tradicionais ao aumento concorrencial. No entanto, parece não existir qualquer investigação acerca do impacto dos operadores de baixo-custo na eficiência técnica dos tradicionais. Assim, este estudo foca-se na relação entre a quota de mercado regional das transportadoras de baixo-custo e a eficiência técnica das companhias aéreas tradicionais sediadas nessa região. Para prosseguir esta investigação, foi implementada uma Análise por Envoltória de Dados de duas etapas. Inicialmente, foram estimadas as pontuações de eficiência técnica com métodos de "bootstrap" para 137 transportadoras de passageiros e, posteriormente, as pontuações foram usadas como variável dependente numa regressão "bootstrapped" truncada para identificar as fontes de eficiência. Os resultados sugerem que uma maior concentração de operadores de baixo-custo numa dada região está associada a uma menor utilização de recursos, por parte dos operadores tradicionais dessa região, para o mesmo nível de produção. Esta relação poderá ser explicada por práticas de gestão mais adequadas que aproximam o modelo tradicional do modelo de baixo-custo

Multi-skill resource-constrained project scheduling problems : models and algorithms

Tese de doutoramento, Estatística e Investigação Operacional (Otimização), Universidade de Lisboa, Faculdade de Ciências, 2018In this dissertation, project scheduling problems with multi-skill resources are investigated. These problems are commonly found in companies making use of human resources or multi-purpose machinery equipment. The general problem consists of a single project comprising a set of activities. There are precedence relations between the activities. Each activity requires one or several skills for being processed and for each of these skills, more than one resource may be needed. The resources have a unitary capacity per time unit and may master more than one skill. The resources can contribute with at most one skill to at most one activity that requires it, in each time unit. It is usually assumed that the resources are homogeneous, i.e., the proficiency at which each skill is performed is the same across all resources that master that skill. Preemption is not allowed, which implies that once an activity starts being processed it cannot be interrupted. When a resource is assigned to perform a skill for an activity, it remains in that status for the whole processing time of the activity. The objective of the problem is to schedule all the activities, satisfying all constraints such that the makespan of the project is minimized. After introducing a framework to the realm of project scheduling problems with multi-skill resources and highlighting the main objectives and contributes of this thesis, a state-of the-art review on the topic is presented. The particular problem investigated in this document is then described in detail and its specific features are discussed. To that end, a continuous-time mathematical formulation from the literature is revisited, an example of the problem is presented and some aspects related to the computation of feasible solutions are discussed. This last topic is of major relevance when dealing with problems that combine personnel staffing with project scheduling. In order to properly assess the quality of solutions obtained by the methodological developments proposed in this thesis, it became necessary to develop an instance generator to build a set of instances larger than those existing in the literature. After formally proposing such generator, we detail the characteristics of the two sets of instances considered for the computational experiments to be performed. In the next sections of the document, the solution methodologies developed within the scope of this thesis are presented and thoroughly discussed. A wide range of mathematical formulations is studied, two of which are first proposed in this document. From the assessment of their ability both to compute feasible and possibly optimal solutions and to derive good lower bounds (stemming from their linear programming relaxations) to the problem, it will become clear that the so-called discrete-time formulations yield the strongest lower bounds whereas a continuous-time formulation from the literature proved to be the most suitable for solving instances of the problem to optimality. This trend is observed for both sets of instances considered. Two constructive lower bound mechanisms proposed for the resource-constrained project scheduling problem are extended to account for the existence of multi-skill resources and multi skill requirements of the activities. The results reveal that such methods improve the lower bounds achieved by the studied mathematical formulations for some instances. Real-world project scheduling problems usually involve a large number of activities, resources and skills. Hence, the use of exact methods such as the standard techniques for tackling the aforementioned mathematical models, is often impractical. When faced with this kind of situations, a project manager may consider preferable to have a good feasible solution, not necessarily an optimal one, within an admissible time, by means of an approximate method. A close look into the problem being investigated in this thesis reveals that it has some features that are not present in some well-studied particular cases of it, namely the notion of skill—multi skill resources and skill requirements of the activities. Hence, with the objective of developing approximate solution methodologies that better exploit the specific characteristics of the problem at hand, two new concepts are introduced: activity grouping and resource weight. The well-known parallel and serial scheduling schemes, proposed originally for the class of resource-constrained project scheduling problems, are extended to our problem setting and the two above-mentioned concepts are incorporated into these two new frameworks. Such frameworks use well-known activity priority rules for defining the order by which the activities are selected to be scheduled and resource weight rules to determine a set of resources that meets the requirements of all the activities to be scheduled at each time with the least total cost (weight). Thereafter, two heuristic procedures making use of those schedule generation schemes are proposed, namely a multi-pass heuristic built upon the parallel scheduling scheme and a biased random-key genetic algorithm. The idea of computing a feasible solution using the so-called backward planning is also considered in both methods. The multi-pass heuristic retrieves the solution with the minimum makespan after performing a specific number of passes, each associated with a unique combination of the considered activity priority rules, the developed resource weight rules and the two precedence networks: forward and backward. The biased random-key genetic algorithm is a metaheuristic whose developed chromosome structure encodes information related to: (i) the priority values of the activities; (ii) the weights of the resources; (iii) how a chromosome is decoded, i.e., the scheduling scheme and precedence network scheme to be used for computing the associated makespan. By embedding all this information into the chromosomes, it becomes possible to take advantage of the evolutionary framework of the biased random-key genetic algorithm, which tends to allow the evolution of such data (change in their values) over time, towards better makespan valued solutions. Three variants of the biased random-key genetic algorithm are considered with regard to the type of scheduling generation scheme to be used for decoding its chromosomes: (i) all chromosomes are decoded with the parallel scheduling scheme; (ii) all chromosomes are decoded with the serial scheduling scheme; (iii) the scheduling scheme to be used for decoding each chromosome depends on the value of the associated parameter which is embedded in the chromosome. The computational results revealed that the proposed multi-pass heuristic is an efficient algorithm for computing feasible solutions of acceptable quality within a small computational time whereas the biased random-key genetic algorithm is a robust algorithm and a more competitive approximate approach for computing feasible solutions of higher quality, especially for harder instances such as those of medium and large dimensions. We conclude this thesis with an overview of the work done and with some directions for further research in terms of methodological developments and of some potentially interesting extensions of the addressed problem

Combining paraconsistent and dynamic logic for Qiskit

Dissertação de mestrado integrado em Engenharia FísicaThis dissertation introduces a logic aimed at combining dynamic logic and paraconsistent logic for application to the quantum domain, to reason about quantum phase properties: Paraconsistent Phased Logic Of Quantum Programs (PhLQP◦ ). In the design PhLQP◦ , firstly the dynamic was built first, Phased Logic Of Quantum Programs (PhLQP). PhLQP is itself a dynamic logic capable of dealing with quantum phase properties, quantum measurements, unitary evolutions, and entanglements in compound systems , since it is a redesign of the already existing Logic Of Quantum Programs (LQP), [14], over a representation of quantum states restricted to a space B equipped with only two computational basis, standard and Hadamard. As instances of applications of the logic PhLQP, there is a formal proof of the correctness of the Quantum Teleportation Protocol, of the 2-party and 4-party of the Quantum Leader Election (QLE) protocol, and of the Quantum Fourier Transform (QFT) operator for 1, 2 and 3 qubits . On a second stage, PhLQP was extended with the connective ◦ known as the consistency operator, a typical connective of the paraconsistent logics Logics of Formal Inconsistency (LFIs), [8, 21, 22]. The definition of consistent quantum state and a set of proper para consistent axioms for the quantum domain, Fundamental Paraconsistent Quantum Axioms (FParQAxs), were provided. An example of application of PhLQP◦ is the possibility of express and prove correctness of the universal quantum gate, the Deustch gate.Esta dissertação introduz uma lógica que tem como objectivo combinar lógica dinâmica e lógica paraconsistente com aplicação no domínio quântico, assim como expressar propriedades relacionadas com fases quânticas: PhLQP◦. No projetar da PhLQP◦, primeiramente concebeu-se a sua componente dinâmica, PhLQP. PhLQP por si só é uma lógica capaz de lidar com propriedades de fases quânticas, evoluções unitárias, e entrelaçamento em sistemas compostos, uma vez que é um redesenhar da já existente LQP, [14], sobre uma representação de estados quânticos restrita a um espaço B munido de apenas duas bases computacionais, standard e Hadamard. Como instâncias de aplicação da lógica PhLQP, há uma prova formal para a correção do protocolo de Teletransporte Quântico, para o protocolo QLE para uma party quer de 2 quer de 4 agentes, e para o operador de QFT de 1, 2, e 3 qubits. Numa segunda fase, PhLQP é extendida com a conectiva ◦, conhecida como operador de consistência, uma conectiva característica das LFIs, [8, 21, 22]. E a partir desta conectiva a definição de estado quântico consistente é um conjunto de axiomas paraconsistentes próprios para o domínio quântico, FParQAxs. Um exemplo de aplicação da PhLQP◦ é a possibilidade de expressar e permitir correção para o comportamento da gate quântica universal, a Deutsch-gate

Local Self‐Governance and the State in South Sudan: Studying Gendered Tenure Relations in Times of Uncertainty

With governance increasingly regarded as co-governance, states' capacity to steer, correct, and discipline a wide range of self-governing actors becomes crucial for states' effectiveness, efficiency, and democracy. This article investigates that capacity and the relationship between formal institutions and customary self-governance in areas of limited statehood. In South Sudan, the field of land governance can be regarded as an area of limited statehood. As land relations are closely connected to clan structures and intra-familial relationships, customary norms and institutions enjoy great legitimacy and are an important locus of local land governance and dispute resolution. The South Sudanese government has promulgated legal provisions for equal rights to property and inheritance that clash head-on with customary notions of gender roles in the family and the preservation of family land. By focusing on the case of women’s land rights in South Sudan, combining literature study with data from exploratory fieldwork in two South Sudanese towns, this article aims to reflect on the cohabitation of customary and formal norms and values and the role formal legal and administrative systems, in areas of limited statehood, can and do play in boundary setting for customary self-governance

Human-in-the-loop image classification

Nos últimos anos, tem havido um crescimento na utilização de Machine Learning e uma necessidade crescente de aplicar modelos de Machine Learning a várias necessidades empresariais, desde a análise dos padrões de compra dos clientes até à tomada de uma decisão empresarial para fazer crescer esse mesmo negócio. Num ambiente empresarial acelarado que nos encontramos atualmente, desenvolver e disponibilizar um bom modelo pode não ser um processo muito célere. O principal motivo são os dados necessários para obter o bom modelo, visto que para obtê-lo pode ser necessário uma grande quantidade de dados e isto pode afetar o tempo de treino do modelo, ou pode ser necessário um pré-processamento dos dados, levando ao aumento do tempo para obter o bom modelo. Com isto, este trabalho apresenta uma possível solução para este problema, onde, através do Active Learning, o humano aplica etiquetas a uma pequena quantidade dados, de seguida são criados vários modelos com parâmetros diferentes para serem treinados até que um intervalo de valores seja atingido. Por fim, algumas métricas serão extraídas e analisadas para concluir qual o melhor modelo. Por fim é apresentada a previsão do modelo em conjunto com uma explicação com o que o modelo considerou importante.In recent years, there has been a growth in the use of Machine Learning and an increasing need to apply Machine Learning models to various business needs, from analysing customer buying patterns to making a business decision to grow that same business. In the fast-paced business environment we currently find ourselves in, developing and delivering a good model may not be a very fast process. The main reason is the data required to obtain the good model, since to obtain it may require a large amount of data and this may affect the training time of the model, or a pre-processing of the data may be required, leading to increased time to obtain the good model. With this, this work presents a possible solution to this problem, where, through Active Learning, the human applies labels to a small amount of data, then several models are created with different parameters to be trained until a range of values is reached. Finally, some metrics will be extracted and analysed to conclude which model is the best. Finally the prediction of the model is presented together with an explanation of what the model considered important

Lean project management: application of lean principles to project management

In today’s challenging business environments, competitive advantage is of utmost importance for organizations and there is a raising demand for profitable solutions that allow organizations to gain competitive advantage. Two of such profitable solutions are Project Management (PM) and Lean Thinking, recognized methodologies for management and production processes. This dissertation proposes a framework to accelerate the performance of projects through PM practices and lean principles. To develop the framework, Project Management Officers (PMOs) of renowned Portuguese companies are interviewed. In the first Stage, interviews are conducted aiming to identify key pain points in PM. Resulting from the first set of interviews, lean principles are applied to PM to remedy the identified pain points and develop a Lean Project Management Framework. The interviews identify the most critical knowledge areas in terms of pain points as Human Resources, Scope, and Procurement Management. In the second stage, experts’ feedback is used to validate the developed framework on four pillars: degree of understanding, alignment towards the major pain points, practical applicability, and orientation towards the final result. All the respondents conceded that the newly developed framework considered the major pain points and was oriented towards the final result, projects success. Nevertheless, some respondents considered that up-front lean knowledge is needed and suggested the development of a framework dictionary to improve understanding and practical applicability. The findings show that the use of traditional lean tools adapted to the PM context can aid in the continuous improvement of processes and practices by conferring role clarity, transparency, and reducing bottlenecks. The Lean Project Management Framework provides a viable approach to overcome the shortcomings of traditional PM practices.Nos desafiantes ambientes de negócio atuais, a vantagem competitiva é essencial para as organizações, havendo uma constante necessidade de encontrar soluções que permitam às organizações obter vantagem competitiva. A Gestão de Projetos e o pensamento Lean são duas destas soluções, reconhecidas nas vertentes de gestão e de ambiente de produção. Esta dissertação propõe um modelo para alavancar o desempenho dos projetos através de práticas de Gestão de Projetos e princípios Lean. Para desenvolver o modelo, são entrevistados PMOs ("Project Management Officers") de empresas portuguesas reconhecidas. Numa primeira fase, as entrevistas visam identificar as principais dificuldades na gestão de projetos. Como resultado destas entrevistas, os princípios lean são aplicados à gestão de projetos para mitigar as dificuldades identificadas e desenvolver um modelo lean de gestão de projetos. As entrevistas identificaram as áreas de conhecimento de Recursos Humanos, Âmbito e Contratação, como as mais criticas em termos de dificuldades. Na segunda fase, a opinião de peritos é utilizada para validar o modelo em quatro pilares: nível de compreensão, principais dificuldades, aplicação prática e orientação ao resultado final. Todos os entrevistados concordaram que o modelo considera as principais dificuldades de gestão de projetos e tem orientação ao resultado final, o sucesso dos projetos. Contudo, alguns entrevistados consideram necessário haver conhecimentos prévios de princípios lean e sugerem o desenvolvimento de um dicionário para o modelo, para melhorar a sua compreensão e aplicação prática. Este estudo demonstra que o uso das ferramentas lean tradicionais adaptadas ao contexto de projetos pode auxiliar na melhoria continua de processos e práticas, conferindo clareza, transparência e reduzindo constrangimentos. O modelo lean de gestão de projetos - "Lean Project Management Framework" - fornece uma abordagem viável para superar as deficiências das práticas tradicionais de gestão de projetos