Motor control of a hub motor for electric skateboard propulsion : a thesis presented in partial fulfilment of the requirements for the degree of Masters in Engineering at Massey University, Palmerston North, New Zealand

Redacted for copyright reasons: Appendix A - Journal Article Published in IEEE International Instrumentation and Measurement Technology Conference (I2MTC 2012). Rowe, A. & Sen Gupta, G. (2012). Instrumentation and control of a high power BLDC motor for small vehicle applications.An electric powered skateboard was designed and built for testing and development of an innovative hub motor propulsion system and motor controller. The electric skateboard prototype is able to reach speeds of over 50km/h and achieve a range of over 35km on a single battery charge. The prototype weighs 8.6kg and can easily be carried by the user. This mode of transport has potential uses in recreational use, motor sports (racing), short commutes, and most notably, in ‘the last mile’ of public transport – getting to and from a train station, bus stop, etc. to the user’s final destination. Typical electric powered skateboards use external motors(s) requiring a power transmission assembly to drive the wheels. The hub motor design places the motor(s) inside the skateboard wheels and drives the wheels directly. This removes the need for power transmission assemblies therefore reductions in size, weight, cost, audible noise, and maintenance are realised. The hub motor built for this prototype has proven to be a highly feasible option over typical drive systems and further improvements to the design are discussed in this report. Advances in the processor capability of low cost microcontrollers has allowed for advanced motor control techniques to be implemented on low cost consumer level motor controllers which, until recent times, have been using the basic ‘Six-Step Control’ technique to drive Permanent Magnet Synchronous Motors. The custom built motor controllers allow for firmware to be flashed to the microcontroller. Firmware was written for the basic motor control technique, Six-Step Control and for the advanced motor control technique, ‘Field Oriented Control’ (FOC). This allowed for the two control techniques to be tested and compared using identical hardware for each. Six-Step Control drives a three phase motor by controlling the inverter output to six discrete states. The states are stepped through sequentially. This results in a square wave AC waveform. Theory shows that this is not optimal as the magnetic flux produced in the stator is not always perpendicular to the magnet poles but rather aligned to the nearest 60°. FOC addresses this by controlling the magnetic flux to always be perpendicular to the magnet poles in order to maximise torque. The inverter is essentially controlled to produce a continuously variable voltage vector output in terms of both magnitude and direction (vector control). Bench testing of the control techniques was performed using two motors coupled together with one motor driving and the other motor running as a generator. The generator motor was shown to provide a highly consistent and repeatable load on the driving motor under test and therefore comparisons could be made between the performance of the motor while controlled under Six-Step Control and FOC. This test indicated that FOC was able to drive the motor more efficiently than Six-Step Control, however the FOC implementation requires further development to achieve greater efficiency under high load demands. Furthermore, on-road testing was performed using the motor controllers in the electric skateboard prototype to compare the performance of the two control techniques in a real world application. The results from this test were inconclusive due to large variation in the results between repeated tests

Large-Amplitude, Pair-Creating Oscillations in Pulsar and Black Hole Magnetospheres

A time-dependent model for pair creation in a pulsar magnetosphere is developed. It is argued that the parallel electric field that develops in a charge-starved region (a gap) of a pulsar magnetosphere oscillates with large amplitude. Electrons and positrons are accelerated periodically and the amplitude of the oscillations is assumed large enough to cause creation of upgoing and downgoing pairs at different phases of the oscillation. With a charge-starved initial condition, we find that the oscillations result in bursts of pair creation in which the pair density rises exponentially with time. The pair density saturates at $N_\pm\simeq E_{0}^2/(8\pi m_ec^2\Gamma_{\rm thr})$, where $E_0$ is the parallel electric field in the charge-starved initial state, and $\Gamma_{\rm thr}$ is the Lorentz factor for effec tive pair creation. The frequency of oscillations following the pair creation burst is given roughly by $\omega_{\rm osc}=eE_0/(8m_ec\Gamma_{\rm thr})$. A positive feedback keeps the system stable, such that the average pair creation rate balances the loss rate due to pairs escaping the magnetosphere.Comment: 21 pages, 6 figures, ApJ submitte

Editorial: From Pedagogic Research to Embedded E-Learning

This Special Issue of Reflecting Education arises from the work of the PREEL project (From Pedagogic Research to Embedded e-Learning) at the Institute of Education from 2006-2008. This project was one of nine HEA/JISC (Higher Education Academy and Joint Information Systems Committee) Pilot Pathfinder Projects and followed on from our involvement in the Pilot Benchmarking of e-Learning Programme. In the benchmarking exercise we identified a lack of coordination between research and practice in e-learning at the IoE as one of our crucial weaknesses, and so our Pilot Pathfinder project concentrated on this theme of building links between e-learning research and practice

Effect of Single Vs Accumulated Bouts of Exercise on Body Composition, Fitness, and Resting Metabolic Rate

PURPOSE: To examine how the effects of accumulated exercise compare to continuous exercise on body composition, VO2max, and metabolic rate. METHODS: Mildly active males (n = 4) and females (n = 5) were randomly selected to perform either 1) continuous exercise consisting of one 30-minute bout of Tabata (1-bout), 2) accumulated exercise consisting of two 15-minute bouts of Tabata (2-bout), or 3) no exercise (control). Both exercise groups performed Tabata three times per week for 4 weeks. Each group had three participants (2 males and 1 female) with the exception of the 2-bout group which had 3 female participants. Changes in body composition (i.e., body mass (kg) and percent body fat (BF%)) were assessed using Dual-Energy X-Ray Absorptiometry (DXA) measurements taken at baseline and after 4 weeks of training. VO2max (ml/kg/min) and resting metabolic rate (kcal/day) were assessed at baseline and after 4 weeks of training using open spirometry on a ParvoMedics True Max 2400 Oxygen Uptake system. For the female participants, both the baseline and 4-week measurements were assessed in the mid-follicular phase of the menstrual cycle. Participants maintained their normal diet throughout the study. Participants were provided with Fitbit watches to keep track of their activity (avg. heart rate & steps per day) during the study. Significant differences (pRESULTS: No significant changes in body mass were detected within the groups (p \u3e .05) or between the groups (p =.72). No significant changes in fat mass were detected within the groups (p \u3e .05) or between the groups (p =.22). With that being said, there was a trend towards a decrease in fat mass within the 2-bout group (1.2 ± .45 kg; p=.061; ES= -.22). No significant changes in BF% (p\u3e.05) were detected within the control or 1-bout group. There was a significant reduction in BF% within the 2-bout group (1.43 ± 0.38%; p=.03; ES= -.63) and there was a significant difference in the change in BF% between the 3 groups (p=.048; ES= -1.2 and -1.8). No significant changes in muscle mass muscle (kg) were detected within the groups (p\u3e.05) or between the groups (p = .17). With that being said, there was a trend towards an increase in muscle mass within the 2-bout group (.77 ± .27kg; p=.059; ES= -.14). No significant changes (p\u3e.05) in resting metabolic rate or VO2max were reported within the groups or between the groups. CONCLUSION: Four weeks of accumulated exercise reduced BF% when compared to no exercise and continuous exercise. Despite the absence of improvement in VO2max and metabolic rate, accumulated exercise throughout the day may still be a valuable exercise mode as it could help people with busy schedules achieve minimum exercise recommendations. Future studies should include 1) a larger sample size, 2) a greater volume of exercise, or 3) a longer period of observation. These modifications may lead to a more valid evaluation of how metabolic health and fitness are influenced by accumulated and continuous exercise

West End Walkers 65+: a randomised controlled trial of a primary care-based walking intervention for older adults:study rationale and design

<p>Background: In Scotland, older adults are a key target group for physical activity intervention due to the large proportion who are inactive. The health benefits of an active lifestyle are well established but more research is required on the most effective interventions to increase activity in older adults. The 'West End Walkers 65+' randomised controlled trial aims to examine the feasibility of delivering a pedometer-based walking intervention to adults aged ≥65 years through a primary care setting and to determine the efficacy of this pilot. The study rationale, protocol and recruitment process are discussed in this paper.</p> <p>Methods/Design: The intervention consisted of a 12-week pedometer-based graduated walking programme and physical activity consultations. Participants were randomised into an immediate intervention group (immediate group) or a 12-week waiting list control group (delayed group) who then received the intervention. For the pilot element of this study, the primary outcome measure was pedometer step counts. Secondary outcome measures of sedentary time and physical activity (time spent lying/sitting, standing or walking; activPAL™ monitor), mood (Positive and Negative Affect Schedule), functional ability (Perceived Motor-Efficacy Scale for Older Adults), quality of life (Short-Form (36) Health Survey version 2) and loneliness (UCLA Loneliness Scale) were assessed. Focus groups with participants and semi-structured interviews with the research team captured their experiences of the intervention. The feasibility component of this trial examined recruitment via primary care and retention of participants, appropriateness of the intervention for older adults and the delivery of the intervention by a practice nurse.</p> <p>Discussion: West End Walkers 65+ will determine the feasibility and pilot the efficacy of delivering a pedometer-based walking intervention through primary care to Scottish adults aged ≥65 years. The study will also examine the effect of the intervention on the well-being of participants and gain an insight into both participant and research team member experiences of the intervention.</p&gt

Is operationalising natural capital risk assessment practicable?

Financial institutions are indirectly exposed to risks associated with the impacts and dependencies on natural capital and ecosystem services of the companies that they invest in, lend to, and insure. This is particularly true for banks lending to agriculture: a sector with both significant impacts and critical dependencies on natural capital. Bank lending is a vital source of new finance for the sector, which is essential to achieve sustainable intensification targets. Yet current credit decision-making practice is still based on conventional financial and management indicators, lacking any systematic assessment of natural capital risks, especially those associated with dependencies. Operationalising natural capital risk assessment requires practicable indicators and data to evaluate the most material natural capital risks for a given sub-sector and geography, but it is unclear to what extent these are available. We assess the practicability of natural capital dependency risk indicators and data sources for a critical case study of Australian sheep production. We find that at least moderately practicable indicators and data sources are available to assess the 11 major dependency risks that are material for this industry. Challenges remain in determining risk thresholds for most indicators, and quantifying risk impacts on profitability. © 2021 Elsevier B.V

Looking inside the ‘black box’ of digital firm scaling : an ethnographically informed conceptualisation

Funding: British Academy (grant number SRG/170550).In recent years there has been an upsurge of interest in firm scaling. Owing to the fact our conceptual and theoretical grasp of this phenomenon remains under-developed, this paper offers a novel conceptualisation of the scaling process based on an in-depth ethnographic study of a London-based digital Fintech. Scaling involves deliberately enacting and surmounting a series of managerial challenges such as human capital re-positioning, business model reconfiguration, customer acquisition and the acquisition of external growth capital. Our theoretical contribution views the micro-foundations of scaling as a distinctive relational process-based phenomenon. Under the conceptual framework posited, entrepreneurial human capital and successful scaling are inextricably interwoven. Entrepreneurial founders and managers are pivotal for orchestrating scaling and our conceptualisation builds upon the trigger point model of firm development, which reinforces the primacy of entrepreneurial agency for optimising growth triggers.Peer reviewe

Expanded Quality Management Using Information Power (EQUIP): Protocol for a Quasi-experimental Study to Improve Maternal and Newborn Health in Tanzania and Uganda.

Maternal and newborn mortality remain unacceptably high in sub-Saharan Africa. Tanzania and Uganda are committed to reduce maternal and newborn mortality, but progress has been limited and many essential interventions are unavailable in primary and referral facilities. Quality management has the potential to overcome low implementation levels by assisting teams of health workers and others finding local solutions to problems in delivering quality care and the underutilization of health services by the community. Existing evidence of the effect of quality management on health worker performance in these contexts has important limitations, and the feasibility of expanding quality management to the community level is unknown. We aim to assess quality management at the district, facility, and community levels, supported by information from high-quality, continuous surveys, and report effects of the quality management intervention on the utilization and quality of services in Tanzania and Uganda. In Uganda and Tanzania, the Expanded Quality Management Using Information Power (EQUIP) intervention is implemented in one intervention district and evaluated using a plausibility design with one non-randomly selected comparison district. The quality management approach is based on the collaborative model for improvement, in which groups of quality improvement teams test new implementation strategies (change ideas) and periodically meet to share results and identify the best strategies. The teams use locally-generated community and health facility data to monitor improvements. In addition, data from continuous health facility and household surveys are used to guide prioritization and decision making by quality improvement teams as well as for evaluation of the intervention. These data include input, process, output, coverage, implementation practice, and client satisfaction indicators in both intervention and comparison districts. Thus, intervention districts receive quality management and continuous surveys, and comparison districts-only continuous surveys. EQUIP is a district-scale, proof-of-concept study that evaluates a quality management approach for maternal and newborn health including communities, health facilities, and district health managers, supported by high-quality data from independent continuous household and health facility surveys. The study will generate robust evidence about the effectiveness of quality management and will inform future nationwide implementation approaches for health system strengthening in low-resource settings

Looking inside the 'black box' of digital firm scaling : an ethnographically informed conceptualisation

In recent years there has been an upsurge of interest in firm scaling. Owing to the fact our conceptual and theoretical grasp of this phenomenon remains under-developed, this paper offers a novel conceptualisation of the scaling process based on an in-depth ethnographic study of a London-based digital Fintech. Scaling involves deliberately enacting and surmounting a series of managerial challenges such as human capital re-positioning, business model reconfiguration, customer acquisition and the acquisition of external growth capital. Our theoretical contribution views the micro-foundations of scaling as a distinctive relational process-based phenomenon. Under the conceptual framework posited, entrepreneurial human capital and successful scaling are inextricably interwoven. Entrepreneurial founders and managers are pivotal for orchestrating scaling and our conceptualisation builds upon the trigger point model of firm development, which reinforces the primacy of entrepreneurial agency for optimising growth triggers