On the dynamics of a nonlinear energy harvester with multiple resonant zones

The dynamics of a nonlinear vibration energy harvester for rotating systems is investigated analytically through harmonic balance, as well as by numerical analysis. The electromagnetic harvester is attached to a spinning shaft at constant speed. Magnetic levitation is used as the system nonlinear restoring force for broadening the resonant range of the oscillator. The system is modelled as a Duffing oscillator with linear frequency variation under static, as well as harmonic excitation. Behaviour charts and backbone curves are extracted for the fundamental harmonic response and validated against frequency response curves for selected cases, using direct numerical integration. It is found that variation in stiffness, together with asymmetric forcing, gives rise to a novel structure of multiple resonant zones, incorporating mono-stable and bi-stable dynamics. Contrary to previously considered bi-stable energy harvesters, cross-well oscillations are realized through a transition from single-well potential energy to double-well with forward frequency sweep. Furthermore, in-well_oscillations present a hardening behaviour, unlike the well-known softening in-well response of bi-stable Duffing oscillators. The analysis shows that the proposed system has multiple resonant responses to a frequency sweep, influenced by consecutive interacting backbone curves similar to a multi-modal system. This combined effect of the transition to bi-stable dynamics and the hardening in-well oscillations induces resonant response of the harvester over multiple distinct frequency ranges. Thus, the system exhibits a broadened frequency response, enhancing its energy harvesting potential

EWOD (electrowetting on dielectric) digital microfluidics powered by finger actuation

We report finger-actuated digital microfluidics (F-DMF) based on the manipulation of discrete droplets via the electrowetting on dielectric (EWOD) phenomenon. Instead of requiring an external power supply, our F-DMF uses piezoelectric elements to convert mechanical energy produced by human fingers to electric voltage pulses for droplet actuation. Voltage outputs of over 40 V are provided by single piezoelectric elements, which is necessary for oil-free EWOD devices with thin (typically <1 μm) dielectric layers. Higher actuation voltages can be provided using multiple piezoelectric elements connected in series when needed. Using this energy conversion scheme, we confirmed basic modes of EWOD droplet operation, such as droplet transport, splitting and merging. Using two piezoelectric elements in series, we also successfully demonstrated applications of F-DMF for glucose detection and immunoassay. Not requiring power sources, F-DMF offers intriguing paths for various portable and other microfluidic applications

A multi-country test of brief reappraisal interventions on emotions during the COVID-19 pandemic.

The COVID-19 pandemic has increased negative emotions and decreased positive emotions globally. Left unchecked, these emotional changes might have a wide array of adverse impacts. To reduce negative emotions and increase positive emotions, we tested the effectiveness of reappraisal, an emotion-regulation strategy that modifies how one thinks about a situation. Participants from 87 countries and regions (n = 21,644) were randomly assigned to one of two brief reappraisal interventions (reconstrual or repurposing) or one of two control conditions (active or passive). Results revealed that both reappraisal interventions (vesus both control conditions) consistently reduced negative emotions and increased positive emotions across different measures. Reconstrual and repurposing interventions had similar effects. Importantly, planned exploratory analyses indicated that reappraisal interventions did not reduce intentions to practice preventive health behaviours. The findings demonstrate the viability of creating scalable, low-cost interventions for use around the world

Innersery : here’s to never growing up – a visual communication exploration in awakening the inner child in adults

The leading psychological theories by Jean Piaget and Lev Vygotsky show that cultivating the mind of a child is the first step to foster creativity in adulthood. The key interest of this research study is to identify how tapping into one’s inner child, a universal concept formulated by Carl Jung, is resourceful to motivate imagination and develop creativity. In the context of art and design, the study investigates how the concept of inner child can be integrated as a vehicle for design and idea generation. Similarly to the concept of inner child in art therapy, where individuals reaps positive effect by reflecting on one's childhood for healing and comfort. Therefore developing an understanding of one's childhood will also allow one to become a more reflective individual. Exploring the possibilities within the realm of Visual Communication, this research aims to deliver a series of publication, illustrative explorations and collaterals to convey the intangible concept of inner child into a brand identity project.Bachelor of Fine Art

Investigating eco-driving technology to reduce fuel consumption and emissions by using an on-board safety device in diesel commercial vehicles in Hong Kong

University of Technology Sydney. Faculty of Engineering and Information Technology.Vehicle emissions have negative impacts on climate change, air quality and human health. The driver is the last major and often overlooked factor that determines vehicle performance. Eco-driving is a relatively low cost and driving-behavior-based method aimed to reduce vehicle fuel consumption and emissions. In this thesis, a safety device was installed on a suite of diesel commercial vehicles to assess its eco-driving capabilities. Because the on-board safety device provided real-time feedback to the driver on their driving performance, actioning of the warnings provided from the safety device could enable not only safety benefits to be achieved but potentially reductions in fuel consumption and emissions as well. Exploring the hypothesis that a safety device can simultaneously facilitate the reduction of fuel consumption and emissions is the principal contribution of this thesis. To investigate the effects of driving behavior on fuel consumption and gaseous emissions of diesel goods vehicles, a portable emissions measurement system was installed on three target vehicles to measure real-driving emissions. In addition, driving and environmental parameters were recorded in the experiments. The on-board safety device installed on the test vehicle was used to record the number of warnings in two separate stages of testing. In the first stage, the number of warnings were recorded while the driver implemented their natural driving style. In the second stage, the number of warnings were recorded but real-time warnings were issued to the driver to improve their driving behavior. The experimental results were evaluated using the Vehicle Specific Power methodology to understand the effects of driving behavior on fuel consumption and gaseous emissions. In this thesis, two studies (three vehicles in total) were conducted to investigate the effects of driving behavior on fuel consumption and emissions of diesel goods vehicles. The first study was conducted to evaluate the effects of an on-board safety device on driving behavior (and fuel consumption and emissions) of two diesel commercial vehicles, including a 5.5 tonnes light goods vehicle and a 16 tonnes medium goods vehicle. In the second study, the effectiveness of the safety device was investigated using a diesel 3.3 tonnes light goods vehicle and 30 drivers with different levels of driving experience were recruited to conduct the on-road emissions experiments. Altogether, the results from this thesis demonstrate that the on-board safety device has a positive impact on fuel consumption and emissions from vehicles through issuing real-time warnings that improve driving behavior

Impact of drivers on real-driving fuel consumption and emissions performance

Eco-driving has attracted great attention as a cost-effective and immediate measure to reduce fuel consumption significantly. Understanding the impact of driver behaviour on real driving emissions (RDE) is of great importance for developing effective eco-driving devices and training programs. Therefore, this study was conducted to investigate the performance of different drivers using a portable emission measurement system. In total, 30 drivers, including 15 novice and 15 experienced drivers, were recruited to drive the same diesel vehicle on the same route, to minimise the effect of uncontrollable real-world factors on the performance evaluation. The results show that novice drivers are less skilled or more aggressive than experienced drivers in using the accelerator pedal, leading to higher vehicle and engine speeds. As a result, fuel consumption rates of novice drivers vary in a slightly greater range than those of experienced drivers, with a marginally higher (2%) mean fuel consumption. Regarding pollutant emissions, CO and THC emissions of all drivers are well below the standard limits, while NOx and PM emissions of some drivers significantly exceed the limits. Compared with experienced drivers, novice drivers produce 17% and 29% higher mean NOx and PM emissions, respectively. Overall, the experimental results reject the hypothesis that driver experience has significant impacts on fuel consumption performance. The real differences lie in the individual drivers, as the worst performing drivers have significantly higher fuel consumption rates than other drivers, for both novice and experienced drivers. The findings suggest that adopting eco-driving skills could deliver significant reductions in fuel consumption and emissions simultaneously for the worst performing drivers, regardless of driving experience

Polymer Coating Integrity, Thrombogenicity and Computational Fluid Dynamics Analysis of Provisional Stenting Technique in the Left Main Bifurcation Setting: Insights from an In-Vitro Model

Currently, the provisional stenting technique is the gold standard in revascularization of lesions located in the left main (LM) bifurcation. The benefit of the routine kissing balloon technique (KBI) in bifurcation lesions is still debated, particularly following the single stent treatment. We compared the latest-generation drug-eluting stent (DES) with no side branch (SB) dilatation “keep it open” technique (KIO) vs. KBI technique vs. bifurcation dedicated drug-eluting stent (BD-DES) implantation. In vitro testing was performed under a static condition in bifurcation silicone vessel models. All the devices were implanted in accordance with the manufacturers’ recommendations. As a result, computational fluid dynamics (CFD) analysis demonstrated a statistically higher area of high shear rate in the KIO group when compared to KBI. Likewise, the maximal shear rate was higher in number in the KIO group. Floating strut count based on the OCT imaging was significantly higher in KIO than in KBI and BD-DES. Furthermore, according to OTC analysis, the thrombus area was numerically higher in both KIO and KBI than in the BD-DES. Scanning electron microscopy (SEM) analysis shows the highest degree of strut coating damage in the KBI group. This model demonstrated significant differences in CFD analysis at SB ostia with and without KBI optimization in the LM setting. The adoption of KBI was related to a meaningful reduction of flow disturbances in conventional DES and achieved results similar to BD-DES