Current Fleet Research Articles

Evaluation of the Effect of Low-Carbon Fuel Blends’ Properties in a Light-Duty CI Engine

<div class="section abstract"><div class="htmlview paragraph">De-fossilization is an increasingly important trend in the energy sector. In the transport sector the de-fossilization efforts have been centered in promoting the electrification of vehicles, nonetheless other pathways, like the use of carbon neutral or carbon-offsetting fuels under current vehicle fleets, are also worth considering. Low-carbon fuels (LCF) can be synthetized from sources that can take advantage of the carbon already present in the atmosphere (either by technologies like direct carbon capture or biological processes like photosynthesis in biofuels) and use energy from renewable sources for the necessary industrial processes. Although, LCFs can be compared to fossil fuels as energy sources for internal combustion engines, their composition is not the same and their properties can modify the engine combustion and emissions. This work evaluates the use of several diesel-like LCFs in a light duty compression ignition engine and correlates the fuel consumption, NOx, soot and CO<sub>2</sub> emissions to the fuel properties. Results indicate that the combined effect of a low density, low aromatic proportion, high energy density and high cetane number Fischer-Tropsch/FAME fuel blend can maintain the fuel consumption and soot emissions close to results with diesel at most engine conditions and reduce NOx emissions 0.5 - 2.5g/kWh. It was also observed that fuels with higher proportions of OMEx (with lower energy density and increased oxygen proportion) can reduce the soot emissions for the same level of NOx emissions with a fuel consumption penalty. Tank-to-wheel CO<sub>2</sub> emissions show little variation between fuels, while the well-to-wheel emissions are proportional to the renewable content.</div></div>

Injury patterns in motor vehicle collision-pediatric pedestrian deaths

Objective To describe fatal pediatric pedestrian injury patterns and correlate them with motor vehicle collision (MVC) characteristics and pedestrian kinematics using data from medicolegal death investigations of MVCs occurring in the current Canadian MV fleet and determine the applicability of the classical “Waddell’s triad” comprising knee, hip (femur) or pelvis and craniocerebral injuries to present data injury patterns. Methods An Injury Data Collection Form was used to extract MV, MVC, pedestrian demographic and injury information from the Office of the Chief Coroner for Ontario database using autopsy data from 2013 to 2018. Injuries were coded using the Abbreviated Injury Scale (AIS) 2015 revision. The study focused on AIS ≥3 injuries utilizing the Maximum Abbreviated Injury Scale (MAIS), MAIS by Body Region (MAISBR) and Injury Severity Score (ISS). Results Between 2013 and 2018, there were 25 pediatric deaths. The pedestrians were either struck and run over (n = 17, 68%; 56% low speed) or struck and projected (n = 8, 32%). Twenty-two deaths were from frontal impacts; three were from reversing vehicles. Fourteen of the 17 (82.4%) run over cases occurred at low speed (<30 km/h). In 9 (36%) cases, the vehicle was turning at impact (right n = 3, left n = 6). A majority of the vehicles had a high hood edge. The head was the most severely injured (median MAISBR = 5 overall and ≤10 years; median MAISBR = 6 for 11–14 years old) followed by the neck (MAISBR = 3 overall; 6–14 years old), and the thorax (median MAISBR = 3 overall; all age groups). For the early adolescents (11-14 years old), the serious injury pattern included the abdomen (median MAISBR = 3.5). Nearly half (n = 11, 44%) sustained brainstem injuries. Over fifty percent of the 16 cases with neck injuries (n = 9, 56.3%) had atlanto-occipital or axial dislocation. Conclusion More than half of the deaths occurred during low speed run overs. MAIS ≥3 injuries trended to a dyad of head and thorax in ≤5 years old, a triad of head, neck, and thorax injuries in children 6–10 years old and a tetrad with the addition of abdominal injuries in pedestrians ≥11 years old. Waddell’s triad was not applicable to the fatal cases in the present study.

Design of separate-effects In-Pile transient boiling experiments at the TREAT Facility

The cladding-to-coolant heat transfer during rapid power excursions, such as reactivity-initiated accidents, remains a crucial area of uncertainty in nuclear reactor safety. This uncertainty impacts the ability to accurately predict fuel performance behavior for these conditions. Improving our understanding of transient cladding-to-coolant heat transfer will enhance our ability to model design-basis accidents and could increase design and safety margins for the current commercial fleet and advanced reactors. To address these issues, the Critical Heat Flux Static Environment Rodlet Transient Test Apparatus experiment was designed and uses a novel approach with a borated stainless-steel heater rodlet that can replicate cladding temperatures experienced during a design-basis reactivity-initiated accident. The design of the rodlet allows for separate-effect testing that eliminates complexities with a fuel and cladding specimen. The rodlet and experiment is instrumented to provide temperature and thermal–hydraulic conditions throughout the transient. The experiment results show that the current correlations in RELAP5-3D are conservative and predict much higher temperatures than measured during the experiments. The data from the experiments will be used to improve our models and understanding of boiling behavior, specifically critical heat flux, under transient conditions.

Charging Infrastructure and Schedule Planning for a Public Transit Network with a Mixed Fleet of Electric and Diesel Buses

Promoting battery electric buses (BEBs) can reduce fuel consumption and air pollution from the transit system. A complete transition from the current diesel fleet to BEBs is costly and time-consuming. Thus, the intermediate solution is a combination of diesel, hybrid, and BEBs. Therefore, a planning framework is required that simultaneously tackles three contiguous aspects of transit electrification and their interconnections, namely charging infrastructure, fleet configuration, and scheduling. Accordingly, this study considers a mixed fleet of diesel and BEBs. It aims to concurrently find (i) the optimal location and capacity of charging infrastructure, considering micro-grid specifications, the impact of distributed energy resources, and time-of-use electricity rates and (ii) optimum operation and refueling strategies. Another objective of this study is to capture the impacts of adverse weather conditions on transit electrification. A mixed-integer problem is proposed and solved using a metaheuristic algorithm based on simulated annealing to minimize system costs, including infrastructure, fleet, and operation costs. A subnetwork of transit in Worcester, Massachusetts, is selected as a case study, including three routes, five candidate charging locations, and three bus types. Findings suggest that BEBs can operate and serve the passenger demand with sufficient charging infrastructure. Sensitivity analyses show that even though high-power chargers are more expensive per piece, they reduce the overall cost as fewer chargers are required. The cost rises for chargers with power of 350 kW or more. It is worth noting that the benefits of BEBs are more significant in smaller buses and are heavily affected by adverse weather conditions.

Introducing Electric Bus Fleets in Rio de Janeiro City Methodology and Analysis

This paper describes the establishment of a methodology aimed at planning the electrification of public urban bus fleets in order to characterize the operational requirements of the battery recharge process. Specifically, it deals with obtaining the behavior of demand and the necessary electrical energy for battery recharging. The effects on the electrical system peak and the resulting environmental benefits are also evaluated by comparing with current internal combustion fleets. An innovative method is applied to a fleet in the city of Rio de Janeiro. The motivation for this work is due to the characteristics of the Brazilian energy mix that is highly favorable to the electrification of urban transport with greater energy efficiency, with a view to reducing the impacts of internal combustion drive and the respective atmospheric emissions that are harmful to the environment. Also, this work offers the steps to establish essential elements, as daily, month and year energy consumption in order to recharge an electric bus fleet and data for the transportation bus company contracts an electric power distribution utility in Brazil. In spite conservative premises were considered, the calculations show electric bus option attractive. The operational energy consumption of diesel bus fleet is 19.10 MJ/km more than three times the consumption of electric bus fleet, this is 6.10 MJ/km. Additionally, 153 ton of fossil CO2 atmospheric monthly emissions are avoided. The results obtained indicate the need for public policies in favor of electric power and the environmental benefits of adopting electric buses.

Condition assessment of cable insulation materials in advanced reactor environments

While existing cable insulation materials are sufficient for use in the current reactor fleet, environmental conditions inside some advanced reactors, such as small modular reactors, will be substantially harsher. The work herein was conducted to assess the performance and overall survivability of several high-temperature, radiation resistant insulation polymers in a simulated small modular reactor environment. The materials evaluated under this research include polyether ether ketone, polyimide, and silicone rubber. These polymers were subjected to 1000 h of environmental stress exposure under two different conditions: 1) high temperature (i.e., 250 °C) in atmospheric pressure and 2) high temperature in a low-pressure vacuum (i.e., less than 2 psia). During the environmental exposure process, each insulation was periodically tested using several materials characterization techniques including Fourier transform infrared spectroscopy, oxidation induction time, and oxidation induction temperature. The objective of this testing was to assess and monitor changes that occurred in the thermal and chemical properties of the materials during the environmental exposures. The overall survivability of each insulation was assessed based on these property changes. The results of this research revealed that the polyimide and polyether ether ketone insulations had significantly better thermal and chemical stability than the silicone rubber during both the high-temperature atmospheric and vacuum exposures. Both polyimide and polyether ether ketone experienced minimal reductions in their chemical and thermal properties over the course of 1000 h in the simulated environments. Based on this research, polyimide and polyether ether ketone show promise as potential base materials for small modular reactor cable insulation.

Towards Zero CO2 Emissions from Public Transport: The Pathway to the Decarbonization of the Portuguese Urban Bus Fleet

The emission of GHG has been steadily increasing in the last few decades, largely facilitated by the transport sector, which has been responsible for more than two-thirds of the manmade emissions in Europe. In cities, one of the possible solutions to decrease the emissions from fossil fuel engines is to replace vehicles with electric ones. This solution can be applied to the urban public fleet, namely by replacing urban buses with electric vehicles. Thus, this research work focuses on the Portuguese case study, which serves as an example of achieving zero CO2 emissions from buses by 2034. This timeframe of replacing the current bus fleet, mostly powered by fossil fuels, with a fully electric fleet is proven to bring financial, environmental, and health benefits to the population. The pathway to the decarbonization of urban public transport will unequivocally contribute directly to the accomplishment of several UN Sustainable Development Goals (SDGs), such as the promotion of affordable and clean energy and sustainable cities and communities, as well as to the increasing climate action (SDGs 7, 11, and 13, respectively). In addition, it will provide an opportunity for the replacement of existing buses that are generally less efficient than electric buses, from both an energy and an environmental point of view. As a result of the methodology, the Portuguese urban bus fleet would be totally replaced by electric buses by 2034 (83% battery-electric and 17% hydrogen-electric), which results in zero CO2 emission from this type of public transport.

Turn off your engine: Reducing idling amongst professional truck drivers

Road transportation is the third largest contributor to nitrogen oxide (NOx) emissions in Norway. Norwegian authorities are working toward replacing current fleet vehicles with zero-emission technologies. Altering driving habits can also contribute up to a 25 % reduction of fuel consumption. The present study reports findings of a behavioral intervention that sought to reduce engine idling among eight professional drivers of biodiesel fueled trucks. Each component was implemented separately. The components included information about the intervention, delayed feedback on idling time (group and individual), and instructions about efficient driving behavior. An 8.6 % reduction in the groups idling was observed. Effect sizes revealed a significant overall decrease in idling (Tau = 0.63, p < 0.01), with variations of which component affected each driver’s behavior the most. In addition, the fuel use was reduced by 6.6 %. The results suggest that multicomponent interventions may be a viable alternative to reduce idling, but further research on variable effects of individual components is recommended. In addition to a replication with a larger group.

Economic costs and environmental impacts of fossil fuel dependency in sub-Saharan Africa: A Nigerian dilemma

Problem statementThe fleet of gasoline generators used for electrical power generation in urban areas in certain parts of sub-Saharan Africa has increased notably. This trend has economic and ecological cost implications for end-users (households and small businesses) and society. Due to lack of data, there exist hardly any empirical studies quantifying the drivers of adoption and the magnitude and of the costs and the impact on people's welfare, energy and environmental degradation. Closing this knowledge gap is critical to reach certain Sustainable Development Goals: 1 – No poverty, 7 – Affordable and clean energy, and 13 – Climate action across sub-Saharan Africa. MethodologyOrdinary Least Squares (OLS) regression was applied to determine the socioeconomic drivers of usage while a levelized- and life cycle cost assessment was used to estimate the economic costs of gasoline generators. The analysis is based on a unique dataset of 100 urban gasoline generator users in Lagos, Nigeria. ResultsPrimary motivation for the adoption of gasoline generators for electrical power generation is frequent on-grid power outages. The extent to which power generators are adopted, relates to the level of education, and correlated to education, income. Furthermore, the average cost of electricity generated through gasoline generators (USD 0.44 or ₦159 per kWh) is substantially higher than on-grid electricity supply (USD 0.06 or ₦20 per kWh). End-users of gasoline generators spend 48 % (ca. USD 99 or ₦35,727) of their monthly (ca. USD 207 or ₦74,702) income on electricity. Furthermore, the annual greenhouse gas (GHG) emissions from the current fleet of generators in Lagos was estimated at 1.5 million tons of carbon dioxide equivalent (CO2e), which is equivalent to the emissions from 326,087 passenger cars. PolicyPolicymakers must push for energy policy and incentives that promote sustainable electricity generation and use among urban households and small businesses in Lagos and throughout Nigeria.

APPLICATION OF THE VEHICLE ALLOCATION METHOD (VAM) IN THE FLEET SIZING PROCESS OF A GERMAN COMPANY IN THE WIND SECTOR

This study sought to apply the Vehicle Allocation Method (VAM) for dimensioning light fleets and identify the results it produces in a multinational company that manufactures, installs and maintains wind turbines. For this, an quantitative research, exploratory, with characteristics of an evaluative case study, based on the documental collection from secondary sources and on the sample, which is composed of light vehicles with circulation in several Brazilian states, supported by parameters such as car life cycle, usage details, among other criteria. The analysis of data collected from an odometer, internal vehicle registration and allocation reports and reports from the supply management system was performed using electronic tabulation (Microsoft Excel). The results showed that data-based actions promote several benefits and allow the company to move towards an optimal inventory based on the adjustments resulting from the results of this study, such as the verified need to replace, reallocate or eliminate about 45% of this company's current fleet.

Decarbonization of the Cargo Shipping Fleet

Abstract In an effort to combat climate change, the International Maritime Organization (IMO) has set ambitious goals for the reduction of greenhouse gas emissions from ships, with a target of at least a 50% reduction of total annual greenhouse gas (GHG) emissions, including carbon, from 2008 levels by 2050, with a further goal of zero GHG emissions within this century. Numerous technologies are under development to address these new goals, but the implementation of these new technologies is quite uncertain. Cargo ship owners face the challenge of determining how to best employ and possibly upgrade the current fleet to meet interim goals while awaiting the maturation of future technologies. This article describes a methodology and computer code that provide a rapid assessment of the impact of various fuel-saving technologies on an existing cargo ship’s fuel consumption, thus providing the ship owner fundamental data indicating which upgrades and practices warrant further, more detailed investigation. Background According to the National Oceanic and Atmospheric Administration, the amount of carbon dioxide in the atmosphere has increased by 1.78 ppm per year on average since 1980, and the increase is accelerating. Through the 1980s and 1990s, the increase was around 1.5–1.6 ppm per year, but the growth rate has averaged 2.4 ppm per year since 2010 (Tans et al. 2020). Rising levels of carbon dioxide in the atmosphere adversely impact the environment in many ways. For example, increased levels of carbon dioxide dissolving in sea water increase the acidity of the oceans; as pH levels drop, organisms like oysters and corals have trouble maintaining their hard shells and skeletons made from calcium carbonate. If pH levels get too low, the calcium carbonate structures begin dissolving (NOAA 2020). Another example can be found in the NOAA Arctic Report Card in which each year shows an Arctic that is becoming warmer, less frozen, and more fragile; the 2020 report includes data on high land-surface air temperatures, low snow extent, low minimum sea-ice extent, and extreme wildfires (Thoman et al. 2020).

Public Transport Decarbonization via Urban Bus Fleet Replacement in Portugal

The transport sector accounts for around one-quarter of the GHG emissions in Europe, and, in Portugal, it represents almost one-third of the total emissions to the atmosphere. Unfortunately, these emissions have increased in recent years. Hence, cities and countries need plans to decarbonize their public transport fleets, and, more specifically, to replace fossil-fueled buses with electric buses that produce zero CO2 emissions. Thus, the main objective of this paper is to present a method to decarbonize the bus fleet in Portugal by a scheduled replacement of the current fleet, which is fueled by fossil fuels, with a completely electric fleet, in fourteen years. The study shows that it is possible to replace all Portuguese urban bus fleets with electric vehicles considering that all vehicles will be replaced when reaching the age of 14 years. Replacing the urban bus fleet with zero-emission buses would aid policymakers and bus companies to reduce the GHGs, and therefore contribute to fulfilling the Sustainable Development Goals of the United Nations 2030 Agenda for Sustainable Development, namely, Goal 13—take urgent action to combat climate change and its impacts.

Well-to-wheel emissions and abatement strategies for passenger vehicles in two Latin American cities.

More stringent standards for engines and fuels are progressively implemented as alternatives to reduce on-road vehicle emissions. While electric vehicles appear as a perfect alternative since their engines do not emit pollutants, wear and dust resuspension (W&R) and indirect emissions associated with electricity production remain significant sources of pollution. This work compares well-to-wheel emissions (WTW) and abatement strategies for various types of passenger vehicles in Bogotá and Santiago for different pollutants (CO, PM2.5, SO2, and NOx) and greenhouse gases like CO2 equivalent (CO2-Eq). Results show that WTW baseline emissions are more extensive in Bogotá than in Santiago (i.e., 58 and 30% for PM2.5 and CO2-Eq), mainly due to the higher vehicle activity and older state of Bogotá's fleet. We also evaluated extreme scenarios to assess the potential of a given vehicle technology or energy source to reduce emissions. We assessed, in particular, the replacement of all current vehicles by (1) conventional technologies with stricter emission standards and (2) battery electric vehicles powered with different energy resources. Our results indicate that replacing the current fleet with modern combustion technologies has a lower reduction potential than battery electric vehicles, but these reductions largely depend on the energy mix. Substitution by electric vehicles powered with electricity from renewable energies is the most efficient scenario in both cities. Finally, results also stress the importance of the resuspension of deposited road dust and brake and tire wear emissions in both cities as a crucial source of PM2.5, which must be better controlled.

The World Casts New Eyes on Nuclear

Images conjured by the mere mention of the term “nuclear energy” are almost always negative. From Chernobyl to Fukushima, the power source has a historically bad reputation and the stigma of catastrophe. Winston Churchill knew those that failed to learn from history were doomed to repeat it, and perhaps it is lessons learned that have so many countries once again casting a keen eye over conventional nuclear energy as a potential key player in the low-carbon future. For the first time in more than a decade, most Japanese are in support of restarting idled nuclear facilities, according to a poll conducted by Nikkei. Rising power prices and the potential for electricity shortages in Tokyo are said to have swayed many back to being in favor of nuclear power just 10 years after the Fukushima disaster. The poll found 53% of respondents in favor of restarting the reactors if safety could be assured, while 38% said they should remain shut. With Russia continuing its invasion into neighboring Ukraine, many European countries are looking to rid themselves of dependence on Russian natural gas imports. Many have grown so dependent they cannot fully shut the stream off for fear of economic collapse, however several are attempting to rework their own energy policies and favoring nuclear as a solution. Both France and the UK have reversed course on nuclear in recent months. Just ahead of Russia’s invasion of Ukraine, French President Emmanuel Macron called for a nuclear renaissance in his country after earlier vowing to cut its reliance on nuclear power. The UK, which gets 15% of its electricity from nuclear power, had vowed to shutter all but one of its plants ahead of the Russian invasion. More recently, Prime Minister Boris Johnson is favoring the construction of new plants and boosting Britain’s electrical generation from nuclear to 25%. As for the US, at the end of 2021 there were 55 commercially operating nuclear power plants with 93 nuclear power reactors in 28 states. The newest nuclear plant to enter service in the US was Watts Bar Unit 2, which began commercial operations in 2016. Two new nuclear reactors are actively under construction: Georgia Power’s Vogtle Units 3 and 4 in Waynesboro, Georgia. A recent Pew survey found that while a majority of Americans (69%) favor the US taking steps to become carbon neutral by 2050, only around a third of US adults (35%) say the federal government should encourage the production of nuclear power, while about a quarter (26%) say the government should discourage it (Fig. 1). This survey was fielded before the Russian invasion and the renewed discussions about nuclear power it has prompted. According to the US Energy Department’s Office of Nuclear Energy, nuclear power currently provides 52% of the US’s carbon-free electricity, and the Biden administration has identified the current fleet of 93 reactors as a vital resource to achieve net-zero emissions economywide by 2050.

Biodiesel Is Dead: Long Life to Advanced Biofuels—A Comprehensive Critical Review

Many countries are immersed in several strategies to reduce the carbon dioxide (CO2) emissions of internal combustion engines. One option is the substitution of these engines by electric and/or hydrogen engines. However, apart from the strategic and logistical difficulties associated with this change, the application of electric or hydrogen engines in heavy transport, e.g., trucks, shipping, and aircrafts, also presents technological difficulties in the short-medium term. In addition, the replacement of the current car fleet will take decades. This is why the use of biofuels is presented as the only viable alternative to diminishing CO2 emissions in the very near future. Nowadays, it is assumed that vegetable oils will be the main raw material for replacing fossil fuels in diesel engines. In this context, it has also been assumed that the reduction in the viscosity of straight vegetable oils (SVO) must be performed through a transesterification reaction with methanol in order to obtain the mixture of fatty acid methyl esters (FAMEs) that constitute biodiesel. Nevertheless, the complexity in the industrial production of this biofuel, mainly due to the costs of eliminating the glycerol produced, has caused a significant delay in the energy transition. For this reason, several advanced biofuels that avoid the glycerol production and exhibit similar properties to fossil diesel have been developed. In this way, “green diesels” have emerged as products of different processes, such as the cracking or pyrolysis of vegetable oil, as well as catalytic (hydro)cracking. In addition, some biodiesel-like biofuels, such as Gliperol (DMC-Biod) or Ecodiesel, as well as straight vegetable oils, in blends with plant-based sources with low viscosity have been described as renewable biofuels capable of performing in combustion ignition engines. After evaluating the research carried out in the last decades, it can be concluded that green diesel and biodiesel-like biofuels could constitute the main alternative to addressing the energy transition, although green diesel will be the principal option in aviation fuel.

Creep deformation phenomena in near-surface carburised layers of 316H stainless steels

The local creep-induced phenomena occurring within the near-surface carburised layer in two pre-carburised type 316H austenitic stainless steels, containing 0.98 or 1.52 wt% Mn, was assessed at 550 °C. The pre-carburisation exposed both steel grades at either 550 °C (8000 h) or 600 °C (3000 h) to simulated CO2-rich gas environment of UK Advanced Gas-cooled Reactors. The local properties within the carburised layer causes a reduction in minimum creep rate as compared to the non-carburised condition. In both steels carburised at 600 °C, ferrite is observed to form in the most heavily carburised regions, including slip bands, during the initial plastic deformation to the target applied stress. The ferrite area fraction further increases with creep strain. Within the ferritic areas, new fine grains are observed in the creep tested specimens and the fraction of high angle grain boundaries is >60%. Those fine grains have a lower degree of lattice strain compared to the surrounding ferrite area and especially to the austenite matrix. The lattice strain localises within the carburised layer, and the formation of ferrite from the strained austenite, and potentially a dynamic recrystallization within the ferrite regions, pinpoints to a dominant strain relief-driven mechanism. Lattice strain localises primarily in the pre-carburised austenite grains and its carbide-decorated boundaries, and induces the continuous formation and refinement of ferrite grains, and the development of intergranular cracks that evolve further into the bulk structure. These results emphasise the necessity to account for environmental-creep interactions at elevated temperatures in structural assessment procedures, in the current gas-cooled fission reactor fleet and beyond into (very) high-temperature Gen IV and advanced modular reactor designs.

Adaptive forecast-driven repositioning for dynamic ride-sharing

AbstractIn dynamic ride-sharing systems, intelligent repositioning of idle vehicles often improves the overall performance with respect to vehicle utilization, request rejection rates, and customer waiting times. In this work, we present a forecast-driven idle vehicle repositioning algorithm. Our approach takes a demand forecast as well as the current vehicle fleet configuration as inputs and determines suitable repositioning assignments for idle vehicles. The core part of our approach is a mixed-integer programming model that aims to maximize the acceptance rate of anticipated future trip requests while minimizing vehicle travel times for repositioning movements. To account for changes in current trip demand and vehicle supply, our algorithm adapts relevant parameters over time. We embed the repositioning algorithm into a planning service for vehicle dispatching. We evaluate our forecast-driven repositioning approach through extensive simulation studies on real-world datasets from Hamburg, New York City, Manhattan, and Chengdu. The algorithm is tested assuming a perfect demand forecast and applying a naïve forecasting model. These serve as an upper and lower bound on state-of-the-art forecasting methods. As a benchmark algorithm, we utilize a reactive repositioning scheme. Compared to this, our forecast-driven approach reduces trip request rejection rates by an average of 3.5 percentage points and improves customer waiting and ride times.

Electric vehicles growth until 2030: Impact on the distribution network power

In the coming years, we will witness a change in the current car fleet sales, from traditional fuel engines towards electrical vehicles (EVs), particularly passenger light-duty vehicles. They plug into the grid and store the electricity in rechargeable batteries; therefore, the widespread adoption of EVs will bring many challenges for the distribution network. Forecasting the impact of EVs on distribution networks is a difficult task given the uncertainty on the potential evolution of their sales.This study forecasts the EVs sales growth for the 2020–2030 decade in 3 possible evolution scenarios, carried out for a given Portuguese regional area. The demanded energy for charging the batteries was estimated, considering one long and one short route. The analysis was applied to three EVs models: Nissan Leaf, Tesla Model 3, and Renault Zoe. Their impacts on the rated power of the distribution network are calculated for the three scenarios, and the results are presented, standing out the insufficient power at peak hours.

A hybrid approach of machine learning and expert knowledge for projection of aircraft operability

Aircraft operational performance is a key driving factor to flight punctuality and airline profitability. The ability of a system to meet its operational requirements in terms of reliability, availability and costs is termed as ’Operability’. It is of high importance for aircraft manufacturers to project operability during the early stages of development of an aircraft in order to make trade-off studies. This paper proposes a hybrid approach of using machine learning and expert knowledge to aid the projection of aircraft operational performance during the early design stages. This approach aims to benefit from the huge amount of in-service data available from the current and past fleet of aircraft. Hence, machine learning techniques are used to learn how different technical issues and their associated maintenance activities impact aircraft operations. Expert knowledge is used to establish the default rules of the simulation model used for the operability projection. Results from machine learning are used to improve these rules allowing one to make holistic projections of the operational performance of future aircraft. This approach allows one to estimate the elapsed time in different operational states of an aircraft like flying, turn-around, etc. which can then be used to calculate different operability Key Performance Indicators (KPIs) like aircraft reliability and maintenance unavailability.

Pathways to achieve future CO2 emission reduction targets for bus transit networks

Apart from electric vehicles, emissions targets for 2025 and 2030 in the heavy-duty transportation sector could be achieved with hybrid powertrains. Moreover, alternatives such as the use of synthetic or e-fuels may also offer a feasible path for transport decarbonization. This work explores different pathways to reduce CO₂ emissions considering the city of Valencia as a case study. The 10 most used bus lines operating in the city are evaluated using their GPS based vehicle speed information with 0D GT Suite simulations. First, the hybridization level for the share of buses was varied from 0 to 100% and the number of different bus types operating in each line was optimised for minimum CO2. Next, the battery and E-motor sizing is optimised for each bus line. Further, an assessment was done assuming 100% electrified fleet, with the 2030 and 2050 electricity generation CO2 footprint projections. Moreover, the potential of e-fuels in the current fleet is also evaluated. The results show that to meet the 2050 target, 100% electrified fleet (with 2050 electricity mix) as well as using e-fuels (generated from renewable sources) in the current fleet are feasible options. However, the e-fuel pathway is more economical than 100% electric fleet.