Towards the reduction of greenhouse gas emissions : models and algorithms for ridesharing and carbon capture and storage

Avec la ratification de l'Accord de Paris, les pays se sont engagés à limiter le réchauffement climatique bien en dessous de 2, de préférence à 1,5 degrés Celsius, par rapport aux niveaux préindustriels. À cette fin, les émissions anthropiques de gaz à effet de serre (GES, tels que CO2) doivent être réduites pour atteindre des émissions nettes de carbone nulles d'ici 2050. Cet objectif ambitieux peut être atteint grâce à différentes stratégies d'atténuation des GES, telles que l'électrification, les changements de comportement des consommateurs, l'amélioration de l'efficacité énergétique des procédés, l'utilisation de substituts aux combustibles fossiles (tels que la bioénergie ou l'hydrogène), le captage et le stockage du carbone (CSC), entre autres. Cette thèse vise à contribuer à deux de ces stratégies : le covoiturage (qui appartient à la catégorie des changements de comportement du consommateur) et la capture et le stockage du carbone. Cette thèse fournit des modèles mathématiques et d'optimisation et des algorithmes pour la planification opérationnelle et tactique des systèmes de covoiturage, et des heuristiques pour la planification stratégique d'un réseau de captage et de stockage du carbone. Dans le covoiturage, les émissions sont réduites lorsque les individus voyagent ensemble au lieu de conduire seuls. Dans ce contexte, cette thèse fournit de nouveaux modèles mathématiques pour représenter les systèmes de covoiturage, allant des problèmes d'affectation stochastique à deux étapes aux problèmes d'empaquetage d'ensembles stochastiques à deux étapes qui peuvent représenter un large éventail de systèmes de covoiturage. Ces modèles aident les décideurs dans leur planification opérationnelle des covoiturages, où les conducteurs et les passagers doivent être jumelés pour le covoiturage à court terme. De plus, cette thèse explore la planification tactique des systèmes de covoiturage en comparant différents modes de fonctionnement du covoiturage et les paramètres de la plateforme (par exemple, le partage des revenus et les pénalités). De nouvelles caractéristiques de problèmes sont étudiées, telles que l'incertitude du conducteur et du passager, la flexibilité de réappariement et la réservation de l'offre de conducteur via les frais de réservation et les pénalités. En particulier, la flexibilité de réappariement peut augmenter l'efficacité d'une plateforme de covoiturage, et la réservation de l'offre de conducteurs via les frais de réservation et les pénalités peut augmenter la satisfaction des utilisateurs grâce à une compensation garantie si un covoiturage n'est pas fourni. Des expériences computationnelles détaillées sont menées et des informations managériales sont fournies. Malgré la possibilité de réduction des émissions grâce au covoiturage et à d'autres stratégies d'atténuation, des études macroéconomiques mondiales montrent que même si plusieurs stratégies d'atténuation des GES sont utilisées simultanément, il ne sera probablement pas possible d'atteindre des émissions nettes nulles d'ici 2050 sans le CSC. Ici, le CO2 est capturé à partir des sites émetteurs et transporté vers des réservoirs géologiques, où il est injecté pour un stockage à long terme. Cette thèse considère un problème de planification stratégique multipériode pour l'optimisation d'une chaîne de valeur CSC. Ce problème est un problème combiné de localisation des installations et de conception du réseau où une infrastructure CSC est prévue pour les prochaines décennies. En raison des défis informatiques associés à ce problème, une heuristique est introduite, qui est capable de trouver de meilleures solutions qu'un solveur commercial de programmation mathématique, pour une fraction du temps de calcul. Cette heuristique comporte des phases d'intensification et de diversification, une génération améliorée de solutions réalisables par programmation dynamique, et une étape finale de raffinement basée sur un modèle restreint. Dans l'ensemble, les contributions de cette thèse sur le covoiturage et le CSC fournissent des modèles de programmation mathématique, des algorithmes et des informations managériales qui peuvent aider les praticiens et les parties prenantes à planifier des émissions nettes nulles.With the ratification of the Paris Agreement, countries committed to limiting global warming to well below 2, preferably to 1.5 degrees Celsius, compared to pre-industrial levels. To this end, anthropogenic greenhouse gas (GHG) emissions (such as CO2) must be reduced to reach net-zero carbon emissions by 2050. This ambitious target may be met by means of different GHG mitigation strategies, such as electrification, changes in consumer behavior, improving the energy efficiency of processes, using substitutes for fossil fuels (such as bioenergy or hydrogen), and carbon capture and storage (CCS). This thesis aims at contributing to two of these strategies: ridesharing (which belongs to the category of changes in consumer behavior) and carbon capture and storage. This thesis provides mathematical and optimization models and algorithms for the operational and tactical planning of ridesharing systems, and heuristics for the strategic planning of a carbon capture and storage network. In ridesharing, emissions are reduced when individuals travel together instead of driving alone. In this context, this thesis provides novel mathematical models to represent ridesharing systems, ranging from two-stage stochastic assignment problems to two-stage stochastic set packing problems that can represent a wide variety of ridesharing systems. These models aid decision makers in their operational planning of rideshares, where drivers and riders have to be matched for ridesharing on the short-term. Additionally, this thesis explores the tactical planning of ridesharing systems by comparing different modes of ridesharing operation and platform parameters (e.g., revenue share and penalties). Novel problem characteristics are studied, such as driver and rider uncertainty, rematching flexibility, and reservation of driver supply through booking fees and penalties. In particular, rematching flexibility may increase the efficiency of a ridesharing platform, and the reservation of driver supply through booking fees and penalties may increase user satisfaction through guaranteed compensation if a rideshare is not provided. Extensive computational experiments are conducted and managerial insights are given. Despite the opportunity to reduce emissions through ridesharing and other mitigation strategies, global macroeconomic studies show that even if several GHG mitigation strategies are used simultaneously, achieving net-zero emissions by 2050 will likely not be possible without CCS. Here, CO2 is captured from emitter sites and transported to geological reservoirs, where it is injected for long-term storage. This thesis considers a multiperiod strategic planning problem for the optimization of a CCS value chain. This problem is a combined facility location and network design problem where a CCS infrastructure is planned for the next decades. Due to the computational challenges associated with that problem, a slope scaling heuristic is introduced, which is capable of finding better solutions than a state-of-the-art general-purpose mathematical programming solver, at a fraction of the computational time. This heuristic has intensification and diversification phases, improved generation of feasible solutions through dynamic programming, and a final refining step based on a restricted model. Overall, the contributions of this thesis on ridesharing and CCS provide mathematical programming models, algorithms, and managerial insights that may help practitioners and stakeholders plan for net-zero emissions

Industrial and Tramp Ship Routing Problems: Closing the Gap for Real-Scale Instances

Recent studies in maritime logistics have introduced a general ship routing problem and a benchmark suite based on real shipping segments, considering pickups and deliveries, cargo selection, ship-dependent starting locations, travel times and costs, time windows, and incompatibility constraints, among other features. Together, these characteristics pose considerable challenges for exact and heuristic methods, and some cases with as few as 18 cargoes remain unsolved. To face this challenge, we propose an exact branch-and-price (B&P) algorithm and a hybrid metaheuristic. Our exact method generates elementary routes, but exploits decremental state-space relaxation to speed up column generation, heuristic strong branching, as well as advanced preprocessing and route enumeration techniques. Our metaheuristic is a sophisticated extension of the unified hybrid genetic search. It exploits a set-partitioning phase and uses problem-tailored variation operators to efficiently handle all the problem characteristics. As shown in our experimental analyses, the B&P optimally solves 239/240 existing instances within one hour. Scalability experiments on even larger problems demonstrate that it can optimally solve problems with around 60 ships and 200 cargoes (i.e., 400 pickup and delivery services) and find optimality gaps below 1.04% on the largest cases with up to 260 cargoes. The hybrid metaheuristic outperforms all previous heuristics and produces near-optimal solutions within minutes. These results are noteworthy, since these instances are comparable in size with the largest problems routinely solved by shipping companies

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Coartação de aorta em crianças até um ano: análise de 20 anos de experiência Coarctation of the aorta in infants under one year of age: an analysis of 20 years of experience

OBJETIVO: Revisão da experiência com diversas técnicas de correção empregadas, nos últimos 20 anos, em crianças menores de um ano de idade. MÉTODOS: No período de 1978 a 1998, foram operados 148 pacientes (pc) consecutivos com coartação de aorta (CoAo) com até um ano de idade, com ou sem defeitos intracardíacos associados. A idade apresentou mediana de 50 dias, 92 pc do sexo feminino (62,1%). O peso foi de 4.367&plusmn;1.897 gramas. O seguimento foi em média de 1.152&plusmn;1.462 dias. A população foi dividida em 3 grupos: Grupo I, CoAo isolada: 74 pc (50%); Grupo II, CoAo e comunicação interventricular (CIV): 41 pacientes (27,7%) e Grupo III, CoAo com malformações complexas: 33 pc (22,3%). RESULTADOS: Mortalidade total foi 43 pc (29%): com menos de 30 dias, foi 53%, p=0,009, OR=4,5, entre 31 e 90 dias, foi 14,7%, p=0,69, e acima de 91 dias, 15%, p=0,004. A probabilidade de sobrevida atuarial de toda a população foi de 67% aos 5 e 10 anos. Trinta e seis pacientes (24,3%) recoartaram, dos quais 18 pacientes (50%) tinham menos de 30 dias, OR=6,35. A incidência de recoartação foi com a técnica de Waldhausen em 4 pacientes (10%) e com a término-terminal clássica em 19 pacientes (26%) p=0.03, e a istmoplastia em 6 pacientes (37,5%). A probabilidade de sobrevida atuarial livre de recoartação aos 5 e 10 anos foi de 69% com a técnica de Waldhausen e 63% com a técnica término-terminal clássica. CONCLUSÃO: Pacientes com menos de 30 dias apresentaram risco aumentado de mortalidade e recoartação. A técnica de Waldhausen em pacientes com mais de 30 dias mostrou-se efetiva. A técnica término-terminal clássica mostrou não ser uma boa opção em todas as faixas etárias, sendo imperativo executar variantes técnicas como término-terminal estendida.<br>OBJECTIVE: A review of experience with techniques of correction used, in the last 20 years, in children younger than one year old. METHODS: In the period from 1978 to 1998, 148 patients (pt) with coarctation of the aorta (CoAo), under one year of age, with or without associated intracardiac defects, were submitted to surgery. Median age 50 days, 92 female pt (62.1%). The average weight was 4,367&plusmn; 1,897 gr. The average follow-up was 1,152&plusmn;1,462 days. The population was divided in 3 groups: Group I, isolated CoAo: 74 pt (50%); Group II, CoAo and interventricular communication (IVC): 41 pt (27.7%) and Group III, CoAo with complex intracardiac malformations: 33 pt (22.3%). RESULTS: The total mortality was of 43 patients (29%). In patients younger than 30 days, the mortality was 53%, p=0.009, DR=4.5, between 31 and 90 days, 14.7%, p=0.69, and over 91 days, 15%, p=0.004. The probability of actuarial survival of the whole population was 67% at 5 and 10 years. Thirty-six patients (24.3%) had recoarctation, from which 18 patients (50%) were younger than 30 days, DR=6.,35. The incidence of recoarctation was with Waldhausen technique in 4 patients (10%) and with the classic termino-terminal technique in 19 patients (26%) p=0.03, and isthmusplastic operation in 6 patients (37.5%). The patients younger than 30 days showed a relative risk for recoarctation de DR=6.35. The probability of actuarial survival, free of coarctation repair, at 5 and 10 years was of 69% with Waldhausen's technique and 63% with the classic termino-terminal technique. CONCLUSION: Patients younger than 30 days showed increased mortality and recoarctation risk. Waldhausen's technique in patients older than 30 days showed effective. The classic termino-terminal technique did not show to be a good option in all age ranges, being imperative to carry out more radical technical variations, such as the extended termino-terminal

Coarctation of the aorta in infants under one year of age: an analysis of 20 years of experience

Objetivo Revisão da experiência com diversas técnicas de correção empregadas, nos últimos 20 anos, em crianças menores de um ano de idade. Métodos No período de 1978 a 1998, foram operados 148 pacientes (pc) consecutivos com coartação de aorta (CoAo) com até um ano de idade, com ou sem defeitos intracardíacos associados. A idade apresentou mediana de 50 dias, 92 pc do sexo feminino (62,1%). O peso foi de 4.367±1.897 gramas. O seguimento foi em média de 1.152±1.462 dias. A população foi dividida em 3 grupos: Grupo I, CoAo isolada: 74 pc (50%); Grupo II, CoAo e comunicação interventricular (CIV): 41 pacientes (27,7%) e Grupo III, CoAo com malformações complexas: 33 pc (22,3%). Resultados Mortalidade total foi 43 pc (29%): com menos de 30 dias, foi 53%, p=0,009, OR=4,5, entre 31 e 90 dias, foi 14,7%, p=0,69, e acima de 91 dias, 15%, p=0,004. A probabilidade de sobrevida atuarial de toda a população foi de 67% aos 5 e 10 anos. Trinta e seis pacientes (24,3%) recoartaram, dos quais 18 pacientes (50%) tinham menos de 30 dias, OR=6,35. A incidência de recoartação foi com a técnica de Waldhausen em 4 pacientes (10%) e com a término-terminal clássica em 19 pacientes (26%) p=0.03, e a istmoplastia em 6 pacientes (37,5%). A probabilidade de sobrevida atuarial livre de recoartação aos 5 e 10 anos foi de 69% com a técnica de Waldhausen e 63% com a técnica término-terminal clássica. Conclusão Pacientes com menos de 30 dias apresentaram risco aumentado de mortalidade e recoartação. A técnica de Waldhausen em pacientes com mais de 30 dias mostrou-se efetiva. A técnica términoterminal clássica mostrou não ser uma boa opção em todas as faixas etárias, sendo imperativo executar variantes técnicas como término-terminal estendida.Objective A review of experience with techniques of correction used, in the last 20 years, in children younger than one year old. Methods In the period from 1978 to 1998, 148 patients (pt) with coarctation of the aorta (CoAo), under one year of age, with or without associated intracardiac defects, were submitted to surgery. Median age 50 days, 92 female pt (62.1%). The average weight was 4,367± 1,897 gr. The average follow-up was 1,152±1,462 days. The population was divided in 3 groups: Group I, isolated CoAo: 74 pt (50%); Group II, CoAo and interventricular communication (IVC): 41 pt (27.7%) and Group III, CoAo with complex intracardiac malformations: 33 pt (22.3%). Results The total mortality was of 43 patients (29%). In patients younger than 30 days, the mortality was 53%, p=0.009, DR=4.5, between 31 and 90 days, 14.7%, p=0.69, and over 91 days, 15%, p=0.004. The probability of actuarial survival of the whole population was 67% at 5 and 10 years. Thirty-six patients (24.3%) had recoarctation, from which 18 patients (50%) were younger than 30 days, DR=6.,35. The incidence of recoarctation was with Waldhausen technique in 4 patients (10%) and with the classic termino-terminal technique in 19 patients (26%) p=0.03, and isthmusplastic operation in 6 patients (37.5%). The patients younger than 30 days showed a relative risk for recoarctation de DR=6.35. The probability of actuarial survival, free of coarctation repair, at 5 and 10 years was of 69% with Waldhausen’s technique and 63% with the classic termino-terminal technique. Conclusion Patients younger than 30 days showed increased mortality and recoarctation risk. Waldhausen’s technique in patients older than 30 days showed effective. The classic termino-terminal technique did not show to be a good option in all age ranges, being imperative to carry out more radical technical variations, such as the extended termino-terminal

Coarctation of the aorta in infants under one year of age : an analysis of 20 years of experience

Objetivo Revisão da experiência com diversas técnicas de correção empregadas, nos últimos 20 anos, em crianças menores de um ano de idade. Métodos No período de 1978 a 1998, foram operados 148 pacientes (pc) consecutivos com coartação de aorta (CoAo) com até um ano de idade, com ou sem defeitos intracardíacos associados. A idade apresentou mediana de 50 dias, 92 pc do sexo feminino (62,1%). O peso foi de 4.367±1.897 gramas. O seguimento foi em média de 1.152±1.462 dias. A população foi dividida em 3 grupos: Grupo I, CoAo isolada: 74 pc (50%); Grupo II, CoAo e comunicação interventricular (CIV): 41 pacientes (27,7%) e Grupo III, CoAo com malformações complexas: 33 pc (22,3%). Resultados Mortalidade total foi 43 pc (29%): com menos de 30 dias, foi 53%, p=0,009, OR=4,5, entre 31 e 90 dias, foi 14,7%, p=0,69, e acima de 91 dias, 15%, p=0,004. A probabilidade de sobrevida atuarial de toda a população foi de 67% aos 5 e 10 anos. Trinta e seis pacientes (24,3%) recoartaram, dos quais 18 pacientes (50%) tinham menos de 30 dias, OR=6,35. A incidência de recoartação foi com a técnica de Waldhausen em 4 pacientes (10%) e com a término-terminal clássica em 19 pacientes (26%) p=0.03, e a istmoplastia em 6 pacientes (37,5%). A probabilidade de sobrevida atuarial livre de recoartação aos 5 e 10 anos foi de 69% com a técnica de Waldhausen e 63% com a técnica término-terminal clássica. Conclusão Pacientes com menos de 30 dias apresentaram risco aumentado de mortalidade e recoartação. A técnica de Waldhausen em pacientes com mais de 30 dias mostrou-se efetiva. A técnica términoterminal clássica mostrou não ser uma boa opção em todas as faixas etárias, sendo imperativo executar variantes técnicas como término-terminal estendida.Objective A review of experience with techniques of correction used, in the last 20 years, in children younger than one year old. Methods In the period from 1978 to 1998, 148 patients (pt) with coarctation of the aorta (CoAo), under one year of age, with or without associated intracardiac defects, were submitted to surgery. Median age 50 days, 92 female pt (62.1%). The average weight was 4,367± 1,897 gr. The average follow-up was 1,152±1,462 days. The population was divided in 3 groups: Group I, isolated CoAo: 74 pt (50%); Group II, CoAo and interventricular communication (IVC): 41 pt (27.7%) and Group III, CoAo with complex intracardiac malformations: 33 pt (22.3%). Results The total mortality was of 43 patients (29%). In patients younger than 30 days, the mortality was 53%, p=0.009, DR=4.5, between 31 and 90 days, 14.7%, p=0.69, and over 91 days, 15%, p=0.004. The probability of actuarial survival of the whole population was 67% at 5 and 10 years. Thirty-six patients (24.3%) had recoarctation, from which 18 patients (50%) were younger than 30 days, DR=6.,35. The incidence of recoarctation was with Waldhausen technique in 4 patients (10%) and with the classic termino-terminal technique in 19 patients (26%) p=0.03, and isthmusplastic operation in 6 patients (37.5%). The patients younger than 30 days showed a relative risk for recoarctation de DR=6.35. The probability of actuarial survival, free of coarctation repair, at 5 and 10 years was of 69% with Waldhausen’s technique and 63% with the classic termino-terminal technique. Conclusion Patients younger than 30 days showed increased mortality and recoarctation risk. Waldhausen’s technique in patients older than 30 days showed effective. The classic termino-terminal technique did not show to be a good option in all age ranges, being imperative to carry out more radical technical variations, such as the extended termino-terminal

Unsupported valvuloplasty in children with congenital mitral valve anomalies. Late clinical results

OBJECTIVE: To analyze late clinical evolution after surgical treatment of children, with reparative and reconstructive techniques without annular support. METHODS: We evaluated 21 patients operated upon between 1975 and 1998. Age 4.67±3.44 years; 47.6% girls; mitral insufficiency 57.1% (12 cases), stenosis 28.6% (6 cases), and double lesion 14.3% (3 cases). The perfusion 43.10±9.50min, and ischemia time were 29.40±10.50min. The average clinical follow-up in mitral insufficiency was 41.52±53.61 months. In the stenosis group (4 patients) was 46.39±32.02 months, and in the double lesion group (3 patients), 39.41±37.5 months. The echocardiographic follow-up was in mitral insufficiency 37.17±39.51 months, stenosis 42.61±30.59 months, and in the double lesion 39.41±37.51 months. RESULTS: Operative mortality was 9.5% (2 cases). No late deaths occurred. In the group with mitral insufficiency, 10 (83.3%) patients were asymptomatic (p=0.04). The majorit y with mild reflux (p=0.002). In the follow-up of the stenosis group, all were in functional class I (NYHA); and the mean transvalve gradient varied between 8 and 12mmHg, average of 10.7mmHg. In the double lesion group, 1 patient was reoperated at 43 months. No endocarditis or thromboembolism were reported. CONCLUSION: Mitral stenosis repair has worse late results, related to the valve abnormalities and associated lesions. The correction of mitral insufficiency without annular support showed good long-term results