Detection and emotional evaluation of an electric vehicle’s exterior sound in a simulated environment

Electric vehicles are quiet at low speeds and thus potentially pose a threat to pedestrians’ safety. Laws are formulating worldwide that mandate these vehicles emit sounds to alert the pedestrians of the vehicles’ approach. It is necessary that these sounds promote a positive perception of the vehicle brand, and understanding their impact on soundscapes is also important. Detection time of the vehicle sounds is an important measure to assess pedestrians’ safety. Emotional evaluation of these sounds influences assessment of the vehicle brand. Laboratory simulation is a new approach for evaluating exterior automotive sounds. This study describes the implementation of laboratory simulation to compare the detection time and emotional evaluation of artificial sounds for an electric vehicle. An Exterior Sound Simulator simulated audio-visual stimuli of an electric car passing a crossroad of a virtual town at 4.47 ms-1 (10 mph), from the perspective of a pedestrian standing at the crossroad. In this environment, 15 sounds were tested using experiments where participants detected the car and evaluated its sound using perceptual dimensions. Results show that these sounds vary significantly in their detection times and emotional evaluations, but crucially that traditional metrics like dB(A) do not always relate to the detection of these sounds. Detection time and emotional evaluation do not have significant correlation. Hence, sounds of a vehicle could be detected quickly, but may portray negative perceptions of the vehicle. Simulation provides a means to more fully evaluate potential electric vehicle sounds against the competing criteria

An investigation on the effect of driver style and driving events on energy demand of a PHEV

Environmental concerns, security of fuel supply and CO2 regulations are driving innovation in the automotive industry towards electric and hybrid electric vehicles. The fuel economy and emission performance of hybrid electric vehicles (HEVs) strongly depends on the energy management system (EMS). Prior knowledge of driving information could be used to enhance the performance of a HEV. However, how the necessary information can be obtained to use in EMS optimisation still remains a challenge. In this paper the effect of driver style and driving events like city and highway driving on plug in hybrid electric vehicle (PHEV) energy demand is studied. Using real world driving data from three drivers of very different driver style, a simulation has been exercised for a given route having city and highway driving. Driver style and driving events both affect vehicle energy demand. In both driving events considered, vehicle energy demand is different due to driver styles. The major part of city driving is reactive driving influenced by external factors and driver leading to variation in vehicle speed and hence energy demand. In free highway driving, the driver choice of cruise speed is the only factor affecting vehicle energy demand

A smart driving smartphone application : real-world effects on driving performance and glance behaviours

A smart driving Smartphone application – which offers real-time fuel efficiency and safety feedback to the driver in the vehicle – was evaluated in a real-world driving study. Forty participants drove an instrumented vehicle over a 50 minute mixed route driving scenario, with 15 being selected for video data analysis. Two conditions were adopted, one a control, the other with smart driving advice being presented to the driver. Key findings from the study showed a 4.1% improvement in fuel efficiency when using the smart driving system, and an almost 3-fold reduction in time spent travelling closer than 1.5 seconds to the vehicle in front. Glance behavior results showed that drivers spent an average of 4.3% of their time looking at the system, at an average of 0.43 seconds per glance, with no glances of greater than two seconds. In conclusion this study has shown that a smart driving system specifically developed and designed with the drivers’ information requirements in mind can lead to significant improvements in real-world driving behaviours, whilst limiting visual distraction, with the task being integrated into normal driving

Exploring a cardio-thoracic hospital ward soundscape in relation to restoration

Hospitals can provide stressful experiences for both patients and medical staff. A well-designed hospital soundscape should avoid adding to negative emotional states (e.g. stress), limit any detrimental cognitive effects (e.g. attentional fatigue), and enable restoration. Experiences of the cardio-thoracic ward soundscape, in a UK public University hospital, were explored via semi-structured interviews with 11 patients and 16 nurses. Thematic coding analysis resulted in 11 key themes including notions of restoration and emotional responses. The themes were used to develop a conceptual model to describe the processes involved in the perception and evaluation of the soundscape. The language used by patients and nurses indicated the emotional response to the soundscape was at times stressful and at others potentially restorative. Coping methods of accepting and habituating to individual sounds were noted. The impact of the patients' and nurses' ability to maintain these coping strategies are discussed in relation to restoration and the temporal variation of the soundscape. A period of 'quiet time' was in operation at the hospital and the importance of this was noted through various responses relating to emotion and restoration. The results suggest the soundscape has potentially, a beneficial role in facilitating restoration thus helping patients' recovery and medical staff's ability to remain productive. This research supports the need to study hospital soundscapes further so that design implications can be considered for the production of a more restorative environment, possibly through the masking/removal of unwanted sounds and optimising positive sounds

Electrochemical modelling of Li-ion battery pack with constant voltage cycling

In a battery pack, cell-to-cell chemical variation, or the variation in operating conditions, can possibly lead to current imbalance which can accelerate pack ageing. In this paper, the Pseudo-TwoDimensional(P2D) porous electrode model is extended to a battery pack layout, to predict the overall behaviour and the cell-to-cell variation under constant voltage charging and discharging. The algorithm used in this model offers the flexibility in extending the layout to any number of cells in a pack, which can be of different capacities, chemical characteristics and physical dimensions. The coupled electrothermal effects such as differential cell ageing, temperature variation, porosity change and their effects on the performance of the pack, can be predicted using this modelling algorithm. The pack charging voltage is found to have an impact on the performance as well as the SEI layer growth. Numerical studies are conducted by keeping the cells at different thermal conditions and the results show the necessity to increase the heat transfer coefficient to cool the pack, compared to single cell. The results show that the thermal imbalance has more impact than the change in inter-connecting resistance on the split current distribution, which accelerates the irreversible porous filling and ageing

Proposing a conceptual framework to develop the hospital soundscape through visual communication

Sound level measurement is used to assess sound within any environment, never more so than in hospitals. This is due to the negative effects that high sound level can have on patients and staff. However, other ways of exploring sound and the soundscape within the hospital context have been used: sound art has conveyed the experiences of heart transplant patients. Art may act as juxtaposition to objective sound level measurement but the two fundamentally attempt to depict attributes of the soundscape. Using theory from design and concepts from art a framework is presented for designing a positive soundscape experience. This is not through the addition of sound per se but through creatively communicating the information contained within a soundscape to enable the everyday listener to interpret a cacophony of hospital sounds more positively. In representing visual communication of sound as a design object, a new way to explore sound may exist

A mass transfer based variable porosity model with particle radius change for a Lithium-ion battery

Micro pore-clogging in the electrodes due to SEI growth and other side reactions can cause adverse effects on the performance of a Lithium-ion battery. The fundamental problem of volume fraction variation and particle radius change during the charge-discharge process in a lithium-ion battery is modelled in this paper with the help of mass transfer based formulation and demonstrated on a battery with LiCoO2 chemistry. The model can handle the volume fraction change due to intercalation reaction, solvent reduction side reaction and the electrolyte density change due to side reaction contamination in the battery. The entire calculation presented in this paper models particle radius and volume fraction together and therefore gives greater accuracy in calculating the volume-specific-area of the reacting particles which is an important parameter controlling the Butler-Volmer kinetics. The mass deposit on the electrode (or loss of lithium) gives an indication of the amount of pre-lithiation required to maintain cell performance while the amount of mass deposited on the SEI helps to decide the safe operating condition for which the clogging of pores and capacity fade will be minimal. Moreover the model presented in this paper has wide applicability in analysing the stress development inside the battery due to irreversible porous filling

Employing consumer electronic devices in physiological and emotional evaluation of common driving activities

It is important to equip future vehicles with an on-board system capable of tracking and analysing driver state in real-time in order to mitigate the risk of human error occurrence in manual or semi-autonomous driving. This study aims to provide some supporting evidence for adoption of consumer grade electronic devices in driver state monitoring. The study adopted repeated measure design and was performed in high- fidelity driving simulator. Total of 39 participants of mixed age and gender have taken part in the user trials. The mobile application was developed to demonstrate how a mobile device can act as a host for a driver state monitoring system, support connectivity, synchronisation, and storage of driver state related measures from multiple devices. The results of this study showed that multiple physiological measures, sourced from consumer grade electronic devices, can be used to successfully distinguish task complexities across common driving activities. For instance, galvanic skin response and some heart rate derivatives were found to be correlated to overall subjective workload ratings. Furthermore, emotions were captured and showed to be affected by extreme driving situations

Structural identifiability of equivalent circuit models for Li-Ion batteries

Structural identifiability is a critical aspect of modelling that has been overlooked in the vast majority of Li-ion battery modelling studies. It considers whether it is possible to obtain a unique solution for the unknown model parameters from experimental data. This is a fundamental prerequisite of the modelling process, especially when the parameters represent physical battery attributes and the proposed model is utilised to estimate them. Numerical estimates for unidentifiable parameters are effectively meaningless since unidentifiable parameters have an infinite number of possible numerical solutions. It is demonstrated that the physical phenomena assignment to a two-RC (resistor–capacitor) network equivalent circuit model (ECM) is not possible without additional information. Established methods to ascertain structural identifiability are applied to 12 ECMs covering the majority of model templates used previously. Seven ECMs are shown not to be uniquely identifiable, reducing the confidence in the accuracy of the parameter values obtained and highlighting the relevance of structural identifiability even for relatively simple models. Suggestions are proposed to make the models identifiable and, therefore, more valuable in battery management system applications. The detailed analyses illustrate the importance of structural identifiability prior to performing parameter estimation experiments, and the algebraic complications encountered even for simple models. View Full-Tex