Model and Solution Methods for the Mixed-Fleet Multi-Terminal Bus Scheduling Problem

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Mixed hybrid and electric bus dynamic fleet management in urban networks: a model predictive control approach

Reducing pollutant emissions and promoting sustainable mobility solutions, including Public Transport, are increasingly becoming key objectives for policymakers worldwide. In order to jointly achieve these goals, careful consideration should be put on the operational cost and management of PT services, in order to promote the adoption of green mobility solutions and advanced management techniques by operators. In this work we develop a dynamic fleet management approach for next generation Public Transportation systems, considering the instance of mixed electric / hybrid fleet. Our objective is that of investigating to what extent electrification, coupled with optimal fleet management, can yield operational cost savings for PT operators, explicitly considering real-time disturbances, including delays, service disruptions etc. We propose a Mixed Integer Linear Program to address the problem of optimal scheduling of a mixed fleet of electric and hybrid / non-electric buses, and employ it as predictor in a Model Predictive Control approach. Test results based upon a real-life scenario showcase how the proposed approach is indeed capable of yielding a sizable reduction in operational costs, even when considerable disturbances arise from the underlying system

European compliance benchmark

The International Legal Research Group -European Compliance Benchmark is acooperation between The European Law Students' Association (ELSA) and K&L Gates. K&L Gates has provided ELSA with research questionsthat24 member and observer groups in our network successfullyinvestigatedin the framework of their respective national legislation. The topic of this LRG centered around the world of Corporate Compliance, as it is one of the hottest legal topicscurrently. What is meant by this is the degree to which companies abide by the regulations set for corporate governance and prevention of criminal measures in a commercial context. The questions of the LRG focused on outlining the relevant rules as well as assessing what the ramifications are for breaking them

Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy

IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced colorectal cancers at diagnosis. OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced oncologic stage and change in clinical presentation for patients with colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all 17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December 31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period), in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was 30 days from surgery. EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery, palliative procedures, and atypical or segmental resections. MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding, lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery, and palliative surgery. The independent association between the pandemic period and the outcomes was assessed using multivariate random-effects logistic regression, with hospital as the cluster variable. RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years) underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142 (56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR], 1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P < .001), and stenotic lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03). CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for these patients

Mixed-fleet single-terminal bus scheduling problem: Modelling, solution scheme and potential applications

Reducing pollutant emissions and promoting sustainable mobility solutions, including Public Transport (PT), are increasingly becoming key objectives for policymakers worldwide. In this work we develop an optimal vehicle scheduling approach for next generation PT systems, considering the instance of mixed electric / hybrid fleet. Our objective is that of investigating to what extent electrification, coupled with optimal fleet management, can yield operational cost savings for PT operators. We propose a Mixed In- teger Linear Program (MILP) to address the problem of optimal scheduling of a mixed fleet of electric and hybrid / non-electric buses, coupled with an ad-hoc decomposition scheme aimed at enhancing the scalability of the proposed MILP. Two case studies arising from the PT network of the city of Luxem- bourg are employed in order to validate the model; sensitivity analysis to fleet design parameters is performed, specifically in terms of fleet size and fleet composition. Conclusions point to the fact that careful modelling and handling of mixed-fleet conditions are necessary to achieve operational savings, and that marginal savings gradually reduce as more conventional buses are replaced by their electric counterparts. We believe the methodology proposed may be a key part of advanced decision support systems for policymakers and operators that are dealing with the on-going transition from conventional bus fleets towards greener transport solutions

Evaluation with doppler sonography of mesenteric blood flow in celiac disease

OBJECTIVE. The aim of this study was to investigate with Doppler sonography the variations of resistance in the superior mesenteric artery, both at fasting and in the postprandial state, in patients with celiac disease. SUBJECTS AND METHODS. Twenty-five patients with celiac disease (20 women, five men; mean age, 30 ± 7 years) and 10 healthy volunteers (seven women, three men; mean age, 28 ± 6 years) were examined with Doppler sonography. Nineteen patients were untreated (no dietary restrictions) and six patients were treated with a gluten-free diet at the time of the examination. Imaging was performed at both fasting and 15 min after an 1890- kJ meal. We introduced a parameter called 'resistive difference,' defined as the mathematic difference between the resistive index measured at fasting (highest value) and that measured at 15 min after the meal (lowest value) as a way to express the postprandial resistive change in the superior mesenteric artery. RESULTS. Untreated patients with flat mucosa showed a resistive difference of 0.03 ± 0.05, followed by untreated patients with mucosal subatrophy (0.05 ± 0.04), treated patients (0.09 ± 0.02), and healthy volunteers (0.12 ± 0.04). A statistically significant difference was noticed between the resistive difference of healthy volunteers and both those of the untreated patients with subatrophy (p = .016) and of the patients with complete atrophy (p = .011), as well as between the resistive difference of the treated patients and both those of the untreated patients with subatrophy (p = .021) and of the patients with complete atrophy (p = .020). CONCLUSION. We believe that Doppler measurement of resistive difference in the superior mesenteric artery can be an effective way to express severity of celiac disease and to document its regression after diet therapy

Mixed hybrid and electric bus dynamic fleet management in urban networks: a model predictive control approach

Abstract—Reducing pollutant emissions and promoting sustainable mobility solutions, including Public Transport, are increasingly becoming key objectives for policymakers worldwide. In order to jointly achieve these goals, careful consideration should be put on the operational cost and management of PT services, in order to promote the adoption of green mobility solutions and advanced management techniques by operators. In this work we develop a dynamic fleet management approach for next generation Public Transportation systems, considering the instance of mixed electric / hybrid fleet. Our objective is that of investigating to what extent electrification, coupled with optimal fleet management, can yield operational cost savings for PT operators, explicitly considering real-time disturbances, including delays, service disruptions etc. We propose a Mixed Integer Linear Program to address the problem of optimal scheduling of a mixed fleet of electric and hybrid / non-electric buses, and employ it as predictor in a Model Predictive Control approach. Test results based upon a real-life scenario showcase how the proposed approach is indeed capable of yielding a sizable reduction in operational costs, even when considerable disturbances arise from the underlying system

Decompositions of the optimal dispatching problem of electric and electric-hybrid buses with energy constraints for Luxembourg City

We are a team of engineers working on a concrete project of Mobility in Luxembourg. We want to solve the problem of optimally determining the sequence of electric and hybrid electric buses, considering both service constraints (schedule adherence) and energy constraints (electric bus charging status, bus recharging scheduling in capacitated facilities) and at the same time ensure a high level of quality of service for the user satisfaction. The problem is formulated as a Mixed Integer Linear Program, with the objective of minimizing the total operational cost for the bus lines in question. System dynamics are captured by twenty sets of constraints, ranging from scheduling adherence to discharge-recharge dynamics. Individual operational costs at the bus level (cost of running an electric / non-electric bus per km, cost of recharging) and at the trip level (penalty due to failed schedule adherence) are fully parametrised, allowing for extensive sensitivity analysis. We investigate a real-life case study based in the city of Luxembourg, where the objective is to reach the all-electric mode for principal urban buses network. Through the model we investigate: the minimum amount of electric buses necessary to perform a day’s schedule for two currently partially electrified lines, without resorting to conventional internal combustion alternatives; the impact of electrifying two additional lines, specifically considering the trade-offs related to either adding new buses or new charging stations at the bus terminal. Finally, we studied how to best decompose the overall problem in several smaller problems, to be able to solve also realistic scenarios and using large real data sets from the Mobility Data owner of Luxembourg. We analysed and compared two kinds of decomposition: a bus line-based decomposition, and a time-based decomposition

Optimal multi-line bus dispatching at terminals with electric charging scheduling constraints

We consider the problem of optimally determining the sequence of electric and conventional internal combustion buses departing from a multi-line bus terminal, considering both service constraints (schedule adherence) and energy constraints (electric bus charging status, bus recharging scheduling in capacitated facilities). The problem is formulated as a Mixed Integer Linear Program, with the objective of minimizing the total operational cost for the bus lines in question. System dynamics are captured by twenty sets of constraints, ranging from scheduling adherence to discharge-recharge dynamics. Individual operational costs at the bus level (cost of running an electric / non electric bus per km, cost of recharging) and at the trip level (penalty due to failed schedule adherence) are fully parametrised, allowing for extensive sensitivity analysis. We investigate a real-life case study based in the city of Luxembourg, where two charging stations have been installed in the central station’s bus terminal. Through the model we investigate: i) the minimum amount of electric buses necessary to perform a day’s schedule for two currently partially electrified lines, without resorting to conventional internal combustion alternatives; ii) the impact of electrifying two additional lines, specifically considering the trade-offs related to either adding new buses or new charging stations at the bus terminal

Fluidized bed co-gasification of industrial wastes for flexible end-use of syngas

The search of alternative to fossil fuels for both energy generation and production of organic chemicals (Chum et al. 2001) calls for usage of renewable and waste materials. In this framework, industrial wastes and residual biomass play an important role, as a possible option for substituting oil and natural gas (Consonni et al. 2009). Thermo-chemical processes can be employed for converting the wastes of interest into valuable gaseous or liquid streams. In particular, thermal gasification is the most attractive process due to multiplicity and versatility of syngas applications, such as a chemical feedstock for producing a number of chemical intermediates, a fuel by itself and an intermediate for the production of other fuels or biofuels. As concerns the fuel production, the possibility to match the producer gas output to the synthesis gas specification during the gasification process is a crucial challenge for researchers due to the significant effect that it could have on the overall process economics. In this work an experimental study of waste co-gasification with biomass was conducted using a pre-pilot plant fluidized bed gasifier in order to explore the possibility of producing a syngas with the specifications required by methanol synthesis. The bed was made of either Ni/γ-alumina or pure γ-alumina particles. More specifically a series of experiments were performed to investigate the effect of bed temperature and steam-to-fuel ratio (S/F) on the outlet gas composition, while keeping fixed the equivalence ratio. The results confirm that the fluidized bed co-gasification of selected biomass and wastes (olive husk/PET and olive husk/Tyre pellets) yields a syngas composition suitable for subsequent methanol production. This is true for 0.6 ≤ S/F ≤ 1, the optimum temperature being about 840 °C for both fuels. The presently reported results represent a sound milestone before further optimization work of the process experimental conditions