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How Reliable Are Drivers’ Statements About Their Engagement in Non-Driving-Related Tasks?
No full textWhen investigating road user behaviour that has the potential to increase risk (e.g., engagement in non-driving-related tasks; NDRTs), we often must rely on self-reported data. However, for a variety of reasons, the reliability of such self-reports can be called into question. To compare self-reported and actual engagement in NDRTs, we utilised a dataset collected as part of the SHRP 2 large-scale naturalistic driving study, which contains video footage of drivers and their activities while driving. A subset of 144 drivers in three distinct age groups was selected for analysis. In each age group, there were 12 drivers each who reported that over the past 12 months, they had either (a) never, (b) rarely, (c) sometimes, or (d) often engaged in potentially distracting activities such as texting, eating, or smoking. For each driver, 120 short episodes of driving were randomly selected, and any observable NDRT engagement was annotated. The analysis of the data revealed a significant association between self-reported and observed frequency of NDRT engagement. However, it also showed a considerable degree of within-group variance. The predictive value of the self-reports was moderate overall. Differences between the age groups emerged with regard to both the extent and the type of observed NDRT engagement. The results indicate that such self-reports, while reasonably accurate at the group level, should be taken with a grain of salt when used to predict individual behaviour
Evaluating the Emergency Braking Abilities of Novice E-Scooter Riders: A Comparative Study of Training Impact
No full textThe collision avoidance abilities of e-scooter riders, and the extent to which training affects those abilities, is not currently known. The purpose of the study was to evaluate the emergency braking abilities and behaviour of novice e-scooter riders and assess to what extent emergency deceleration rates are improved after attending a practical training course. The mean deceleration rates of twenty-nine participants were measured during emergency braking manoeuvres on two types of e-scooters. Supplementary information was recorded using video footage and a questionnaire. Approximately half the participants attended a practical training course intended for novice e-scooter riders. A second test session was conducted with all the participants one week later using the same test method. In the first test session, the mean deceleration rates during the emergency braking manoeuvres in dry conditions were 0.306 g and 0.267 g for the commercial and private specification e-scooters, respectively. A small sample of damp tests were completed on the private specification scooter and the mean deceleration rate was 0.237 g. Participants who had received practical training improved by an average of 13% and 19% on the respective scooters. Participants who did not receive training made no improvement. This study provides a dataset that could be used by reconstructionists when investigating road traffic collisions involving e-scooters. The notable improvements in collision avoidance ability made by those who had received practical training may assist policymakers when considering the impact that in-person tuition may have on improving overall safety and reducing the number collisions involving e-scooters
Ansätze zur optimierten Laderegelung von Elektrofahrzeugen in einem Car-Sharing-System: unter der Nutzung lokaler regenerativer Elektroenergien im Vergleich
No full textElektrofahrzeuge sind bereits eine klimafreundliche Alternative im urbanen Verkehr. Ihr volles Potenzial entfalten sie jedoch, wenn ihre Ladevorgänge zeitlich so gesteuert werden, dass lokal verfügbare regenerative Elektroenergie bestmöglich genutzt wird. Die vorliegende Dissertation untersucht verschiedene Ansätze zur optimierten Laderegelung in Car-Sharing-Systemen, bei denen Ladezeitpunkte dynamisch an die Verfügbarkeit von Wind- und Photovoltaikenergie, Netzlast sowie an den Mobilitätsbedarf anpassen. Auf Basis von Prognosedaten, empirischen Verfahren, algorithmischen Optimierungen und Scheduling wird gezeigt, wie sich der Anteil erneuerbarer Energien am Ladevorgang deutlich steigern lässt, ohne die Verfügbarkeit der Fahrzeuge einzuschränken oder Verteilnetze zu überlasten. Die Ergebnisse verdeutlichen, dass intelligente Regelstrategien nicht nur ökologische Vorteile bringen, sondern auch die Integration der Elektromobilität in ein nachhaltiges und stabiles Elektroenergieversorgungssystem wesentlich unterstützen.:1 Einleitung
2 Elektromobilität und ihr Einfluss auf das Elektroenergiesystem
3 Analytische Beschreibung der Randbedingungen
4 Geregeltes Laden von Elektrofahrzeugen
5 Ergebnisse
6 Schlus
Investigating the Potential of Different Gamification Approaches Designed to Motivate Smart Charging – a Cross-Cultural Comparison
No full textThis study explores the potential of various gamification approaches to enhance user motivation for smart charging of electric vehicles, with a particular focus on cross-cultural preferences. Four distinct gamification strategies - rewards, streaks, feedback, and social comparison - were each implemented in a dedicated smart charging app design. To evaluate them, six focus groups were conducted with 30 participants from Germany, Ireland, China, and India, enabling both qualitative and quantitative insights into user perceptions and preferences. The findings indicate that, while reward-based gamification was generally the most appealing, it provided the greatest motivation when coupled with monetary incentives. Additionally, app designs that incorporated positively reinforcing elements were preferred over a non-gamified alternative. Cultural differences primarily influenced the appeal of social comparison. Based on the results, the paper provides actionable recommendations for designing culturally sensitive gamified applications to support the transition to smart charging behaviours
The subcategorization of English adverbs: A feature-based clustering approach
No full textThe category of the adverb in the English language is notoriously heterogeneous, and Crystal (1995: 211) even considers it a “dustbin category” which combines such disparate members as the manner adverb happily, the intensifier very, the comparative more and the postmodifier indeed (cf. e.g. Quirk et al. 1985: 63, 66).
In order to determine the most appropriate subclassification of the category of the adverb in English, the present contribution presents original research based on a dataset of the 2500 most frequent words in the British National Corpus (Sanchez 2008). The 206 adverbs in this high-frequency sample were coded with regard to their decomposability into semantic components, word-family integration, language of origin, age, underlying word formation process (simple vs. compound vs. derivational), suffix type used (if applicable) and semantic class (e.g. time or manner).
Using a tree plot, we first investigated whether the adverbs in our dataset are more similar to the lexical or the grammatical parts of speech, but with no conclusive evidence.
We then used a recent clustering approach (consensus clustering; cf. Chiu 2018) and an innovative visualization in the form of an adaptation of parallel coordinate plots for multivariate categorical data to determine whether cluster analyses can be used to automatically subcategorize words assigned to the traditional category of the adverb into meaningful subcategories. We did indeed find a linguistically meaningful categorization into three clusters that are distinguished with regard to the word formation type characteristic of the group members, namely simplex adverbs (e.g. next), -ly suffixations (e.g. regularly) and other complex word formations (e.g. meanwhile).
Finally, our results indicate that the presence or absence of an adjectival base is a much better criterion for the subcategorization of English adverbs than the property of permitting inflection (or not), as the agreement with our clusters is much more pronounced
Influence of electrolyte flow on plasma electrolytic polishing of additively manufactured lattice structures
No full textAdditive manufacturing enables the production of complex geometries such as lattice structures,
widely used in aerospace and medical applications for their high strength-to-weight ratio. However,
achieving a high-quality surface finish on internal features remains a challenge. Plasma electrolytic
polishing (PEP) offers a promising solution. The process is like electro chemical machining (ECM),
but the electrolytes are low concentration salts dissolved in water and with much higher voltage,
hence the vapor-gaseous envelope is formed around the workpiece. The Faraday effect limits the
polishing of lattice structures but forced electrolyte flow may improve the polishing of internal
structures. This study investigates the effect of flushing through a BCC lattice structure using a
custom nozzle during PEP. Cross-sectional analysis of lattice structures shows that 4 l min-1 flow
achieved the greatest material removal across all layers. Increasing the flow rate resulted in lower
material removal rate, most likely due to the disruption of the vapor-gaseous envelope. The results,
supported by strut diameter evolution across layers, emphasize the importance of optimizing
electrolyte flow to effectively polish internal features
Necessity and Proposed Procedure for a Classification of Security Features in Shared Automated Vehicles Based on the Kano Model
No full textShared automated vehicles (SAVs) will contribute to tackling several of today’s mobility problems. In rural areas, they will help to improve transport links to underserved regions and in congested urban environments, they have the potential to free up valuable road space by bundling individual journeys. However, their beneficial effect is strongly dependant on high acceptance rates. In conventional shared mobility concepts, non-verbal, verbal or physical assaults on passengers by fellow travellers are a major obstacle to acceptance and negatively influence usage rates. There is reason to assume that harassment and other anti-social behaviour will also take place in SAVs and prior studies were able to identify in-vehicle security as a major passenger concern. In order to achieve high acceptance rates and benefit from the advantages SAVs can bring, it is indispensable to provide users with vehicle interiors that ensure a secure and fearless journey. Currently, little is known about user preferences regarding possible security features and there are no interior concepts that prioritize in-vehicle security. Furthermore, there is so far no classification of security features that could serve as a guideline for vehicle manufacturers. This paper suggests the use of the Kano-Model as a way to efficiently assess and categorise different in-vehicle security features and proposes a dual method approach to experimental validation
Interpretable Passenger Discomfort Prediction in Automated Driving Using Transformers
No full textThis study employs a Temporal Fusion Transformer (TFT) model to forecast passenger discomfort in the context of highly automated driving, utilizing time-series data collected from a driving simulator. The objective is to assess whether transformer-based models can provide accurate and interpretable predictions of subjective discomfort levels during vehicle driving. Two variants of the TFT model were developed, referred to as TFT-full and TFT-restricted. Both models were trained on simulator data from 100 participants. Additionally, they were compared to DeepAR, an autoregressive time-series model used as a baseline. Results showed that the TFT-restricted model performed better than both the TFT-full and DeepAR models. The TFT-restricted model achieved the best overall performance, with a Mean Absolute Error (MAE) of 0.042 and a Root Mean Square Error (RMSE) of 0.133. These findings support the suitability of transformer-based models for discomfort detection in automated vehicles
High-Precision Planetary Terrain Rendering with Real-World Data on Ellipsoidal Surfaces for Interactive Visualization
No full textReal-time rendering of virtual globes represents the pinnacle of large-scale terrain rendering. Modeling the surface of an entire planet has vast applications, ranging from Geographic Information Systems (GIS) to educational software. However, the immense scale of planetary terrain introduces significant challenges, including level-of-detail (LOD) management and numerical precision limitations. This thesis provides an overview of the fundamental challenges in planetary terrain rendering and examines existing solutions. Building on this foundation, a comprehensive framework for planetary terrain rendering is presented, supporting terrains on an ellipsoidal base shape, which accurately represents the true spheroid form of planets, such as the WGS84 reference ellipsoid. The framework covers key aspects such as view-dependent terrain geometry management, terrain data streaming, and an accurate spatial reference system (SRS) that integrates seamlessly with the quadtree-based subdivision of terrain geometry and data. A novel approach to maintaining high precision despite the limitations of floating-point accuracy on the Graphics Processing Unit (GPU) is introduced. This method leverages a Taylor series approximation to compute positions on the ellipsoidal surface relative to the viewer. Additionally, a hierarchical system of coordinate transformations is proposed to accurately represent terrain positions at various scales. A crucial feature of any virtual globe framework is its ability to render multiple localized datasets on top of the planetary surface. This thesis presents a method for achieving this, supported by a preprocessing pipeline that converts arbitrary georeferenced raster files into datasets compatible with the rendering system. An extensive open-source reference implementation is provided, and the framework is evaluated using multiple datasets
Advances in the interpretation of the material removal by studying the surface of nitriding steel for pulsed electrochemical machining
No full textRemoval techniques offer broad opportunities in the machining of high-strength materials. Besides
typical difficult-to-machine non-ferrous materials such as titanium alloys and nickel-based alloys,
high-strength steels are also receiving increasing attention. However, due to lower alloy quantities
these have a higher undesirable corrosion tendency. This increases the challenges in
electrochemical precision machining, which typically occurs in a saltwater environment.
This research shows investigations of the surface after pulsed electrochemical machining (PECM)
of nitriding steel 31CrMoV9. Using the material characterization method DIN SPEC 91399, the
removal is analyzed as a function of current density by varying the voltage and sinking speed. The
surface was studied by a combination of visual inspection and a morphology analysis using DIN EN
ISO 25178. Three clearly distinguishable dissolution areas were found. Besides the visual presence
of the passivation, inhomogeneities in the removal diagram were traced back to a pronounced
increase of roughness of the machined surface