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Stone, Barry A. "Control strategies for functional electrical stimulation induced cycling". Thesis, University of Glasgow, 2005. http://theses.gla.ac.uk/1533/.
Texto completo da fonteResumo:
Functional Electrical Stimulation cycling ergometers and mobile cycling systems have been developed over a number of years to allow Spinal Cord Injured persons to exercise. Standard able bodied exercise tests are adapted and applied to paraplegic cyclists. A modified recumbent tricycle is instrumentated with an electric motor and sensors to measure cadence and the power produced by the cyclist at the crank. They are then integrated to a stimulator and a laptop computer. The tricycle is mounted on an indoor cycling trainer to provide a novel test bed for the implementation of exercise testing. Controllers are desired to control cadence and power during cycling. Identification of input-output data for the cadence-motor loop and the power-stimulation loop is undertaken. Three muscle groups are stimulated on a paraplegic subject to produce power. Models are identified of the power and cadence systems. Thereafter controllers are designed, via polynomial methods. The results show that the controllers are robust during cadence tracking, power tracking and for disturbance rejection. The controllers can be accurately applied to exercise testing protocols. The concept of VO2 control is induced. VO2 is the rate of oxygen uptake during exercise. VO2-power dynamics are identified and as before a model is fitted to the measured data. Controllers are designed and further modified, as the understanding of the VO2 dynamics is developed. This is through a series of tests to improve the accuracy of the control. The results illustrate that VO2 control is a novel and practical application. These findings develop the field of functional Electrical Stimulation Induced Cycling within the laboratory. However further work is required to develop this application outside laboratory conditions.
2
Kapur, Kishen Narain. "Mechanical and electrical characterization of IC leads during fatigue cycling". Diss., Online access via UMI:, 2009.
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Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Electrical and Computer Engineering, 2009.Includes bibliographical references.
3
Schauer, Thomas. "Feedback control of cycling in spinal cord injury using functional electrical stimulation". Thesis, University of Glasgow, 2006. http://theses.gla.ac.uk/1524/.
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This thesis is concerned with the realisation of leg cycling by means of FES in SCI individuals with complete paraplegia. FES lower-limb cycling can be safely performed by paraplegics on static ergometers or recumbent tricycles. In this work, different FES cycling systems were developed for clinical and home use. Two design approaches have been followed. The first is based on the adaptation of commercially available recumbent tricycles. This results in devices which can be used as static trainers or for mobile cycling. The second design approach utilises a commercially available motorised ergometer which can be operated while sitting in a wheelchair. The developed FES cycling systems can be operated in isotonic (constant cycling resistance) or isokinetic mode (constant cadence) when used as static trainers. This represents a novelty compared to existing FES cycling systems. In order to realise isokinetic cycling, an electric motor is needed to assist or resist the cycling movement to maintain a constant cadence. Repetitive control technology is applied to the motor in this context to virtually eliminate disturbance caused by the FES activated musculature which are periodic with respect to the cadence. Furthermore, new methods for feedback control of the patient’s work rate have been introduced. A one year pilot study on FES cycling with paraplegic subjects has been carried out. Effective indoor cycling on a trainer setup could be achieved for long periods up to an hour, and mobile outdoor cycling was performed over useful distances. Power output of FES cycling was in the range of 15 to 20 W for two of the three subjects at the end of the pilot study. A muscle strengthening programme was carried out prior and concurrent to the FES cycling. Feedback control of FES assisted weight lifting exercises by quadriceps stimulation has been studied in this context.
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Abdulla, Shwan Chatto. "Intelligent control for a novel assist mechanism in functional electrical stimulation cycling". Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/6849/.
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Duffell, Lynsey Diane. "An investigation of functional electrical stimulation cycling for people with spinal cord injury". Thesis, King's College London (University of London), 2007. https://kclpure.kcl.ac.uk/portal/en/theses/an-investigation-of-functional-electrical-stimulation-cycling-for-people-with-spinal-cord-injury(4560dd1b-b718-4a0f-8589-1c0f44ba2815).html.
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Armstrong, Ellen L. "Activate-CP: Let's Ride a Bike! Efficacy of a functional-electrical-stimulation cycling, adapted cycling and goal-directed training program for children with cerebral palsy". Thesis, Griffith University, 2020. http://hdl.handle.net/10072/400454.
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Background: Advances in modern medicine and a proliferation of high-quality research focused on the prevention, diagnosis and early intervention for children with Cerebral Palsy (CP) have led to remarkable declines in the incidence and severity of CP in high income countries over the past decade. The result is less children are being born with CP and the severity of motor impairments and associated conditions are decreasing. There is, however, more work to be done to develop safe and effective rehabilitative interventions for children living with CP who are marginally ambulant or non-ambulant (Gross Motor Function Classification Scale (GMFCS) levels III-V).
Some children with CP experience declining gross motor function as they transition from childhood to adolescence, resulting in the loss of ability to perform sit-to-stand (STS) transfers, ambulate or participate in leisure activities. Goal-directed training approaches to improve gross motor function in children with CP are substantiated by high quality evidence, with a strong focus on ambulant children (GMFCS I-III). Adapted cycling is part of a burgeoning area of interest for healthcare workers who are committed to finding safe and inclusive modes of exercise for children with CP across all GMFCS levels. It can be difficult, however, for some children to self-propel on an adapted bike, and the efficacy of cycling to improve gross motor function is unclear. Functional Electrical Stimulation (FES) cycling is a novel technology that may provide opportunities for children with CP to strengthen their lower limbs, improve functional independence and increase their capacity to cycle on an adapted bike in the community. In light of the scarcity of evidence-based rehabilitative interventions appropriate for both ambulant and non-ambulant children with CP, a program of goal-directed training, FES-cycling and adapted cycling was developed.
Aim: This doctoral program aimed to: (i) determine the efficacy of cycling-based interventions to improve functional outcomes in children aged 2-18 years (GMFCS levels I-V); (ii) design an intervention of goal-directed training, FES-cycling and adapted cycling based on current evidence (Activate-CP); (iii) test the efficacy of Activate-CP to improve gross motor function, goal performance and satisfaction in children with CP compared to usual care; (iv) determine if functional improvements gained during Activate-CP training could be retained, eight weeks after completing the training, and (v) explore the experiences of participants and parents in the Activate-CP training program.
Methods: A systematic review and meta-analysis was completed to inform the development of Activate-CP: an eight-week program of goal-directed training, FES-cycling and adapted cycling. A waitlist randomized controlled trial (RCT) protocol was designed and implemented to test the efficacy of Activate-CP to improve gross motor function, goal performance and satisfaction in ambulant and non-ambulant children with CP (GMFCS II-IV), aged 6-18 years old. Participants were randomized to the intervention group (n=11) who commenced Activate-CP training immediately, or a waitlist control group (n=10). Outcomes were assessed at baseline, post-training and at eight-weeks post-training (follow-up). Primary outcomes were gross motor function assessed by the Gross Motor Function Measure (GMFM) and goal performance/satisfaction assessed by the Canadian Occupational Performance Measure (COPM). Secondary outcome measures included the five times sit-to-stand test (FTSTS), Pediatric Evaluation of Disability Index (PEDI-CAT), Participation and Environment Measure-Children and Youth (PEM-CY) and cycling power output and resistance. Pre-training, post-training and follow-up data from both groups were pooled to investigate retention of effects at eight-weeks follow-up. Semi-structured interviews were conducted at the end of Activate-CP and a thematic analysis undertaken to explore participant’s experiences.
Results: A systematic review identified nine studies (N=282) on cycling interventions for children with CP and suggested that cycling may improve muscle strength (effect size (ES): 0.77-0.93), cardiorespiratory function (ES: 1.13-1.77) and gross motor function (ES: 0.91) in children with CP. Studies were limited by small sample sizes and a lack of follow-up testing and focused predominantly on stationary cycling among ambulant children. The Activate-CP RCT was designed, developed, and delivered to 21 participants (intervention group n=11; waitlist group n=10). The intervention group had significant and clinically meaningful improvements on the GMFM (MD=7.7, 95% CI 2.3-12.6; p=0.007), COPM (MD=4.4; 95% CI 3.9-5.3; p<0.001;ES=3.32), and peak cycling resistance (MD=3.4; 95% CI 1.0-5.8; p=0.009) immediately post-training compared to the waitlist group. There were no significant between-group differences immediately post-training on secondary outcomes. Participants retained meaningful improvements on the GMFM and COPM that were higher than baseline values at eight-weeks follow up. Improvements in cycling power output and resistance, PEDICAT daily activities, PEMCY environmental barriers and FTSTS were also retained at follow-up. A thematic analysis of 17 interviews with participants (n=11) and their carers’ (n=18) revealed four major themes: facilitators and challenges to program engagement; perceived outcomes; the FES-cycling experience; and previous cycling participation.
Conclusion: Activate-CP was effective to improve gross motor function, goal performance and satisfaction and peak cycling resistance in ambulant and non-ambulant children with CP, and improvements were retained in the short term. Findings reported in this thesis support Activate-CP as a new and alternative intervention to improve functional outcomes in children with CP. Facilitators and challenges to participant engagement were identified and hold practical relevance for clinicians who work with children with CP who have goals to improve functional independence or cycling. Environmental and personal factors should be carefully considered when developing future rehabilitation programs for ambulant and non-ambulant children with CP, to maximise opportunities for success.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School Allied Health Sciences
Griffith Health
Full Text
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Hochman, Lori. "Effects of Functional Electrical Stimulation Cycling versus Cycling Only on Walking Performance and Quality of Life in Individuals with Multiple Sclerosis: A Randomized, Clinical Pilot Study". Diss., NSUWorks, 2018. https://nsuworks.nova.edu/hpd_pt_stuetd/75.
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Background: Functional Electrical Stimulation (FES) stimulates peripheral nerves via electrical current to evoke muscle contractions and when combined with lower extremity cycling (LE), creates patterned leg movements. Previous studies demonstrated FES cycling is safe and effective in the spinal cord injury and stroke populations with improvements seen in walking speed, muscle mass, and bone density. Few studies have applied FES cycling to a neurodegenerative disorder, such as multiple sclerosis (MS). The aim of this study is to assess the effect of an 8-week training program using FES cycling, compared to Cycling Only, in people with MS (PWMS). Methods: Using a sample of convenience, PWMS were recruited to participate and randomized to the FES Cycling group or the Cycling Only group. Both groups received training three-times per week for 8- weeks using a LE ergometer. Scores on the 6 Minute Walk Test (6MWT), Times 25-Foot Walk Test (T25FW), Five Times Sit-to-Stand (5XSST), and Timed Up and Go (TUG), and spatiotemporal measure of gait were collected at baseline, (before the 1st session), 4-weeks (before the 13th session), 8-weeks (after the 24th training session), and at 4-week follow-up. Scores on the MS Quality of Life-54 (MSQOL), Modified Fatigue Impact Scale (MFIS), Multiple Sclerosis Walking Scale-12 (MSWS-12), and Activities-specific Balance Confidence Scale (ABC) were collected at baseline, 8-weeks, and at 4-week follow-up. Results: Fourteen participants (8 female, 6 male, mean age = 53.64 ± 10.16 years; Patient Determined Disease Steps (PDDS) mean = 3.71 ± .091) completed the training. Cycling power output significantly increased in both groups over time (FES Cycling, p = 0.03; Cycling only p = 0.004), but no differences were found between groups (p = 0.08). The Cycling Only group demonstrated a slightly larger effect size for power output than the FES Group (d = 0.72 vs. 0.66). Immediately after the intervention period, scores on the 6MWT, 5XSST, and MFIS, and subscores of the MSQOL-54 improved significantly, but changes did not consistently favor one group over the other (p >0.05). There were no significant differences between groups on any of the outcome measures. Conclusions: FES Cycling or Cycling Only may be an effective intervention for improving walking endurance, sit-to-stand, and QOL in PWMS. This unique pilot study compared FES cycling versus Cycling Only for PWMS using a customized progression protocol. Further research with larger sample sizes are needed to better understand the effects of FES Cycling on PWMS.
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Miceli, Christina. "Seasonal Cycling in Electrical Resistivities at Ten Thin Permafrost Sites, Southern Yukon and Northern British Columbia". Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23463.
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Permanent electrode arrays were set up at ten monitoring sites from Whitehorse, Yukon, to Fort St. John, British Columbia, in order to gain a clearer perspective of the effectiveness of electrical resistivity tomography (ERT) monitoring over an annual cycle of freezing and thawing. This research forms part of a longer-term project that is attempting to use ERT to examine changes in permafrost resulting from climate change. Inter-site and intra-site variability were examined by installing and maintaining data-loggers to monitor active layer and shallow permafrost temperatures, air temperatures, and snow depths at each site from August 2010 – August 2011. Additional site information was collected on each ERT survey date, including frost table depths, snow depths, and vegetation heights. Based on nearby community records, the climate in the region has been warming by a rate of 0.3 to 0.5 °C per decade since 1970. The permafrost at all ten sites was characteristic of sporadic discontinuous and isolated patches permafrost zones, and is classified as Ecosystem-protected. Nine of the ten permafrost sites had permafrost that was thinner than the 14 or 7 m penetration depth of the ERT survey (three-layer system consisting of an active layer, permafrost, and sub-permafrost perennially unfrozen zone). The most predictable results were achieved at the two-layer system site (active layer overlying permafrost to the base of the profile) in each of its virtual resistivity boreholes, relative resistivity change comparisons, and mean near-surface apparent resistivity progressions. ERT is an effective method of delineating permafrost boundaries in thin permafrost environments and does show strength when monitoring areas of seasonally frozen ground. Repeat surveys at a site indicate seasonal changes in three-layer conditions, but not as predictably as those in a two-layer system. In order to receive the most accurate information regarding permafrost extent and thickness, it appears ideal to conduct ERT surveys annually, within the same month as the previous year’s survey.
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Sun, Feng-Bin 1963. "Environmental stress screening (ESS) by thermal cycling and random vibration: A physical investigation". Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282309.
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Temperature cycling and random vibration have proven to be the two most effective environmental stress screens. This study presents an extensive research on the physical quantification and optimization of temperature cycling and random vibration screens. For temperature cycling screen, a general model has been proposed to describe a typical temperature response cycle and a typical power-temperature response cycle. The least-squares parameter estimates for the two modified Arrhenius models are derived. Two general models for quantifying the equivalent aging acceleration factor of a typical temperature cycle with or without power cycling, considering both reaction rate stress and temperature change rate stress and also incorporating the temperature dependence of the activation energy, are derived. A closed form solution under the mixed-exponential life distribution assumption and an iteration equation solution under the Weibull distribution assumption, of the optimum number of temperature cycles for a specified post-screen field Mean Residual Life (MRL) goal, are established. For the random vibration screen, the distributions of the cumulative damage and fatigue life, under both stationary narrow-band and stationary wide-band random stressings, are derived under both-normal, semi-normal, and Markov-process assumptions. A bimodal mixed P-S-N diagram is proposed, from the failure physics point of view, to describe the fatigue strength of a non-screened unit. The concepts of the threshold S-N curve and the screening probability for fatigue defect precipitation are proposed to facilitate the quantification of random vibration screens. Finally, the closed form solution of the optimum vibration duration for a specified screening probability is derived under both-normal, semi-normal and Markov-process assumptions, respectively.
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McRae, Calum George Alexander. "Approaches to functional electrical stimulation induced cycling and application for the child with a spinal cord injury". Thesis, University of Glasgow, 2006. http://theses.gla.ac.uk/1526/.
Texto completo da fonteResumo:
In the hope of more compact and user-friendly approaches to FES-cycling through the incorporation of modern sensor and computing technology, two new hip-angle-based strategies (both of which utilise a limb-mounted sensor) and a “traditional” crank-angle-based strategy have been developed and incorporated into a PDA-based multi-functional FES system. Through both simulation and tricycle-based experiments, all three approaches have been shown to provide practical stimulation activation timing. The second research focus concerns the development of two FES-cycling systems which are suitable for a spinal cord injured child, and methods to facilitate the intended use of both devices. A standard child’s tricycle has been modified with appropriate instrumentation for FES-cycling and testing involving its target population was carried out at a US-based paediatric research hospital. These experiments culminated in the demonstration of FES-cycling by an untrained seven year old T4/T6 (motor complete) subject, and the evolution of the device into one which should be able to meet the specific needs of spinal cord injured children. A second system with integrated motor has also been developed. As well as offering motor assistance, this device incorporates additional instrumentation to allow investigation into exercise and training capabilities. Experiments have been undertaken to validate this equipment and it is now ready for future pilot work involving paediatric subjects. The two research foci in this thesis represent what are, in our opinion, important routes that FES-cycling should take to progress into the home environment and also allow participation of a population who have potentially the most to gain from using it.
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Sinclair, Peter James. "Forward dynamic modelling of cycling for people with spinal cord injury". Thesis, The University of Sydney, 2001. http://hdl.handle.net/2123/512.
Texto completo da fonteResumo:
A forward dynamic model was developed to predict the performance of Spinal Cord Injured (SCI) individuals cycling an isokinetic ergometer using Neuromuscular Electrical Stimulation (NMES) to elicit contractions of the quadriceps, hamstring and gluteal muscles. Computer simulations were performed using three inter-connected models: a kinematic model of segmental linkages, a muscle model predicting forces in response to stimulation, and a kinetic model predicting ergometer pedal forces resulting from muscle stimulation. Specific model parameters for SCI individuals were determined through measurements from isometric and isokinetic contractions of the quadriceps muscles elicited using surface stimulation. The muscle model was fitted to data resulting from these isolated experiments in order to tailor the model's parameters to characteristics of muscles from SCI individuals. Isometric data from a range of knee angles were used to fit tendon slack lengths to the rectus femoris and vastus muscles. Adjustments to the quadriceps moment arm function were not able to improve the match between measured and modelled knee extension torques beyond those using moment arms taken from available literature. Similarly, literature values for constants from the muscle force - velocity relationship provided a satisfactory fit to the decline in torque with angular velocity, and parameter fitting did not improve this fit. Passive visco-elastic resistance remained constant for all velocities of extension except the highest (240 deg/s). Since knee angular velocities this high were not experienced during cycling, a visco-elastic dampener was not included within the present cycling model. The rise and fall in torque following NMES onset and cessation were used to fit constants to match the rate of change in torque. Constants for the rise in torque following NMES onset were significantly altered by changes in knee angle, with more extended angles taking longer for torque to rise. This effect was small, however, within the range of angles used during cycling, and consequently was not included within the cycling model. The decline in torque after NMES cessation was not affected by knee angle. A period of five minutes cyclical isometric activity of the quadriceps resulted in torque declining by more than 75% from rested levels. The activation time constants were largely unaffected by this fatigue, however, with only a small increase in the time for torque to decline, and no change in rise time or the delay between stimulation changes and resulting torque changes. The cycling model, therefore, did not incorporate any effect for changes in activation timing with fatigue. Performance of the full model was evaluated through measurements taken from SCI individuals cycling a constant velocity ergometer using NMES elicited contractions of the quadriceps, hamstring and gluteal muscles. Pedal transducers measured forces applied to the pedals for comparison between measured and modelled values. A five minute period of continuous cycling using just the quadriceps muscles produced similar results to those found for isolated knee extension. External power output dropped by 50% over the five-minute period, however there was no change in the pattern of torque production with fatigue. Cycling experiments were conducted using single muscle groups across a range of NMES firing angles. Experimental protocols were designed to seek the firing angles for each muscle that maximised power output by that group. Changes in power output in response to firing angle changes were not large, however, in comparison to the effects of cumulative fatigue and inconsistent power output between trials. This lead to large uncertainties in the determination of those firing angles that maximised power output by each muscle. Results suggest that NMES firing angles to maximise power output by the quadriceps muscles were relatively similar for each subject. For the hamstring muscles, however, substantial differences were observed in the range of firing angles that maximised power output. Results for the gluteal muscles were variable, with some subjects not applying any measurable torque to the cranks, even with maximal stimulation applied. The model produced a good match to experimental data for the quadriceps muscles, both in the shape of pedal force curves and the firing angles that maximised external power output. The individual variability in hamstring responses was not, however, predicted by the model. Modification of the relative size of the hamstrings' moment arms about the hip and knee substantially improved the match between measured and modelled data. Analysis of results suggests that individual variability in the relative size of these moment arms is a major cause of variation in individual's response to hamstring stimulation. There were apparent limitations in the model's ability to predict the shape of crank torques resulting from stimulation of the gluteus maximus muscle. It is suggested that further research be conducted to enable modelling of this muscle using a range of fibre lengths and moment arms.
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Sinclair, Peter James. "Forward dynamic modelling of cycling for people with spinal cord injury". University of Sydney. Exercise and Sport Science, 2001. http://hdl.handle.net/2123/512.
Texto completo da fonteResumo:
A forward dynamic model was developed to predict the performance of Spinal Cord Injured (SCI) individuals cycling an isokinetic ergometer using Neuromuscular Electrical Stimulation (NMES) to elicit contractions of the quadriceps, hamstring and gluteal muscles. Computer simulations were performed using three inter-connected models: a kinematic model of segmental linkages, a muscle model predicting forces in response to stimulation, and a kinetic model predicting ergometer pedal forces resulting from muscle stimulation. Specific model parameters for SCI individuals were determined through measurements from isometric and isokinetic contractions of the quadriceps muscles elicited using surface stimulation. The muscle model was fitted to data resulting from these isolated experiments in order to tailor the model's parameters to characteristics of muscles from SCI individuals. Isometric data from a range of knee angles were used to fit tendon slack lengths to the rectus femoris and vastus muscles. Adjustments to the quadriceps moment arm function were not able to improve the match between measured and modelled knee extension torques beyond those using moment arms taken from available literature. Similarly, literature values for constants from the muscle force - velocity relationship provided a satisfactory fit to the decline in torque with angular velocity, and parameter fitting did not improve this fit. Passive visco-elastic resistance remained constant for all velocities of extension except the highest (240 deg/s). Since knee angular velocities this high were not experienced during cycling, a visco-elastic dampener was not included within the present cycling model. The rise and fall in torque following NMES onset and cessation were used to fit constants to match the rate of change in torque. Constants for the rise in torque following NMES onset were significantly altered by changes in knee angle, with more extended angles taking longer for torque to rise. This effect was small, however, within the range of angles used during cycling, and consequently was not included within the cycling model. The decline in torque after NMES cessation was not affected by knee angle. A period of five minutes cyclical isometric activity of the quadriceps resulted in torque declining by more than 75% from rested levels. The activation time constants were largely unaffected by this fatigue, however, with only a small increase in the time for torque to decline, and no change in rise time or the delay between stimulation changes and resulting torque changes. The cycling model, therefore, did not incorporate any effect for changes in activation timing with fatigue. Performance of the full model was evaluated through measurements taken from SCI individuals cycling a constant velocity ergometer using NMES elicited contractions of the quadriceps, hamstring and gluteal muscles. Pedal transducers measured forces applied to the pedals for comparison between measured and modelled values. A five minute period of continuous cycling using just the quadriceps muscles produced similar results to those found for isolated knee extension. External power output dropped by 50% over the five-minute period, however there was no change in the pattern of torque production with fatigue. Cycling experiments were conducted using single muscle groups across a range of NMES firing angles. Experimental protocols were designed to seek the firing angles for each muscle that maximised power output by that group. Changes in power output in response to firing angle changes were not large, however, in comparison to the effects of cumulative fatigue and inconsistent power output between trials. This lead to large uncertainties in the determination of those firing angles that maximised power output by each muscle. Results suggest that NMES firing angles to maximise power output by the quadriceps muscles were relatively similar for each subject. For the hamstring muscles, however, substantial differences were observed in the range of firing angles that maximised power output. Results for the gluteal muscles were variable, with some subjects not applying any measurable torque to the cranks, even with maximal stimulation applied. The model produced a good match to experimental data for the quadriceps muscles, both in the shape of pedal force curves and the firing angles that maximised external power output. The individual variability in hamstring responses was not, however, predicted by the model. Modification of the relative size of the hamstrings' moment arms about the hip and knee substantially improved the match between measured and modelled data. Analysis of results suggests that individual variability in the relative size of these moment arms is a major cause of variation in individual's response to hamstring stimulation. There were apparent limitations in the model's ability to predict the shape of crank torques resulting from stimulation of the gluteus maximus muscle. It is suggested that further research be conducted to enable modelling of this muscle using a range of fibre lengths and moment arms.
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RALSTON, Keira. "THE IMMEDIATE EFFECTS of FUNCTIONAL ELECTRICAL STIMULATION CYCLING on URINE OUTPUT, OEDEMA and SPASTICITY after SPINAL CORD INJURY". Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/9986.
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Question: Does functional electrical stimulation (FES) cycling increase urine output and decrease lower limb swelling and spasticity in people with recent spinal cord injury (SCI)? Design: Randomised cross-over trial. Methods: Fourteen participants with a recent motor complete SCI were consecutively recruited from two SCI units in Sydney. Intervention: Participants were randomised to an experimental phase followed by a control phase or vice versa, with a 1-week washout period in between. The experimental phase involved FES cycling four times a week for two weeks and the control phase involved standard rehabilitation for two weeks. Assessments by a blinded assessor occurred at the beginning and end of each phase. Allocation was concealed and an intention-to-treat analysis was performed. Outcome measures: The primary outcome was urine output (mL/hr) and the secondary outcomes were lower limb circumference and spasticity using the Ashworth Scale, and the Patient Reported Impact of Spasticity Measure (PRISM. In addition, participants were asked open-ended questions to explore their perceptions about treatment effectiveness. Results: All participants completed the study. The mean between-group differences (95% CI) for urine output was 82 ml/hr (-35 to 199; p = 0.15). The mean between-group differences (95% CI) for lower limb swelling, spasticity (Ashworth), and PRISM were -0.1 cm (-1.5 to 1.2), -1.9 points (-4.9 to 1.2) and -5 points (-13 to 2), respectively. All point estimates of treatment effects favoured FES cycling. Participants reported many different benefits from FES cycling. Conclusion: There were no clear effects of FES cycling on urine output, swelling and spasticity even though all point estimates favoured FES cycling and participants perceived therapeutic effects.
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Sanz, Desco Raul. "Life Length and Stress Tests of Electric Machines for Electric Vehicles". Thesis, KTH, Skolan för kemivetenskap (CHE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214554.
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Electrical machines have been widely used along the last decades with large life length under operating conditions. However, they will become more important in the upcoming years because of the emerging electric car industry. Thus, the maintenance cost of this technology can be reduced by extending the lifetime in the electrical machines. Despite the fact that existing numerous studies within the life length in these devices, only few study the effect of the thermomechanical stresses of insulation. The core of this master thesis is to study the influence of these stresses in the insulation material of a winding. The tested electrical machines were subjected to different test conditions, allowing to analyse multiple aging effects in the winding. To achieve these effects, power cycling tests were carried out on stators, where the windings were tested in cycles with different ΔT and two cooling methods: air cooling and oil cooling. The results showed large aging differences between the two cooling methods employed. The aging effect in the oil cooling method was higher than in the air cooling method for the same number of cycles. However, the aging effects regarding the same cooling process had not wide differences between the different test temperatures.
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Brand, Vitali. "Contamination- induced Interfacial Resistance in Ohmic Microswitch Contacts". Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/448.
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Ohmic nanoswitches have been recently regarded to complement transistors in applications where electrical current leakage is becoming a problem. Although the solid state metal oxide silicon field effect transistor (MOSFET) has fueled a global technology revolution, it is now reaching its performance limits because of device leakage. To avoid electric field-induced damage in MOSFETs, operating voltage and hence threshold voltage must be reduced as linewidth is reduced. However, below a limit, the current cannot be turned off. The ohmic switch approach solves this problem because an air gap that separates the electrical contacts provides excellent electrical isolation when the relay is open. Some applications require these relays to perform billions to trillions of cycles, yet typical devices that are exposed to ambient environment degrade electrically after just a few thousand cycles. A critical challenge here is that trace amounts of volatile hydrocarbons in air adsorb on the electrical contact surfaces for a large variety of coating materials, causing an insulating deposit to form that prevents signal transmission during switch closure. We address this challenge by exploring the interactions of hydrocarbon contaminants with contact materials and operating environment on device lifetime. Our materials of choice are Pt, a common contact material in switch applications due to its resistance to wear, and RuO2, which is believed to be somewhat resistant to hydrocarbon adsorption. We test our devices in N2 and O2 background environments with controlled hydrocarbon contaminant concentrations. We illustrate that the insulating hydrocarbon deposit can be electrically broken down and its resistance lowered. We show how electrical contacts that have degraded electrically due to contamination can have their performance restored to the original level by actuating them in clean N2-O2 environment. It is then shown how this process creates a highly conductive carbonaceous deposit that protects the contact from wear. It is also v demonstrated that RuO2 does not exhibit contaminant-induced degradation even at very high hydrocarbon presence, as long as O2 is also present. These results show that even though the contaminant is ubiquitous in the environment, there are many ways to reduce its effect on ohmic switches.
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Jeon, Justin Yong. "Effects of functional electrical stimulation-assisted cycling exercise on glucose tolerance and insulin sensitivity in people with spinal cord injury". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28951.pdf.
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Baranauskienė, Neringa. "The residual effect of eccentric concentric prior exercise on pulmonary gas exchange and muscle electrical activity during cycling of different intensity". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2013~D_20131014_105852-02810.
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It is well established that unaccustomed eccentric concentric exercise evokes delayed onset muscle soreness (DOMS) (MacIntyre et al., 2001; Dannecker et al., 2005, 2008; Fredsted et al., 2008; Lewis et al., 2012), muscle fibre disarrangement (Hortobagyi et., al., 1998; Stupka et al., 2001; Carlsson et al., 2007), inflammatory cell emission into blood (Stupka et al., 2001; Laaksonen et al., 2006), increase of the activity of blood plasma creatinkinasis (Stupka et al., 2000; Chen et al., 2010; Skurvydas et al., 2010), decrease of muscle force production (Chen et al., 2010; Semmler et al., 2007; Skurvydas et al., 2010) and decrease of aerobic work capacity (Black, Dobson, 2012). The aforementioned functional, sensory, biochemical and structural changes independently from each other are displayed immediately after eccentric exercise and stay for up to 7 days, dependence on the level of damage (Clarkson et al., 1992; Skurvydas et al., 2000; Stupka et al., 2000, 2001; MacIntyre, 2001; Totsuka et al., 2002; Nottle, Nosaka, 2007; Tofas et al., 2008; Lewis et al., 2012; Paulsen et al., 2012).
It is still not clear what acute and residual effect of eccentric exercise on the pulmonary gas exchange is had during different intensity work. It was determined that one hour after eccentric concentric exercise, there increases absolute VO2 during moderate (Zaičenkovienė, Stasiulis, 2010) and heavy intensity loads (Ratkevičius et al., 2006). 48 hours after eccentric exercise, when the... [to full text]Atlikta daug tyrimų, kuriais nustatyta, kad neįprasti ekscentriniai koncentriniai fiziniai pratimai sukelia vėluojantį raumenų skausmą (MacIntyre et al., 2001; Dannecker et al., 2005, 2008; Fredsted et al., 2008; Lewis et al., 2012), raumeninių skaidulų pažaidą (Hortobagyi et al., 1998; Stupka et al., 2001; Carlsson et al., 2007), uždegiminių ląstelių išskyrimą į kraują (Stupka et al., 2001; Laaksonen et al., 2006), kraujo plazmos kreatinkinazės aktyvumo padidėjimą (Stupka et al., 2000; Chen et al., 2010; Skurvydas et al., 2010), raumenų jėgos sumažėjimą (Chen et al., 2010; Semmler et al., 2007; Skurvydas et al., 2010) bei aerobinio darbo galingumo sumažėjimą (Black, Dobson, 2012). Minėti funkciniai, sensoriniai, biocheminiai ir struktūriniai pakitimai nepriklausomai vienas nuo kito pasireiškia iš karto po ekscentrinių krūvių ir išlieka iki 7 parų, priklausomai nuo pažaidos dydžio (Clarkson et al., 1992; Skurvydas et al., 2000; Stupka et al., 2000, 2001; MacIntyre, 2001; Totsuka et al., 2002; Nottle, Nosaka, 2007; Tofas et al., 2008; Lewis et al., 2012; Paulsen et al., 2012). Vis dar nėra aišku, koks yra ūminis ir liekamasis ekscentrinio krūvio poveikis kvėpavimo dujų apykaitos rodiklių kaitai įvairaus intensyvumo darbo metu. Nustatyta, kad, praėjus vienai valandai po ekscentrinio koncentrinio krūvio, padidėjo absoliučios VO2 reikšmės vidutinio (Zaičenkovienė, Stasiulis, 2010) ir didelio intensyvumo krūvių metu (Ratkevičius et al., 2006). Praėjus 48 val. po ekscentrinio... [toliau žr. visą tekstą]
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Hartmann, Richard Lee II. "An Aging Model for Lithium-Ion Cells". University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1226887071.
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Ferrario, Chiara. "Functional electrical stimulation (FES) leg cycling exercise in paraplegia : a pilot study for the definition and assessment of exercise testing protocols and efficacy of exercise". Thesis, University of Glasgow, 2006. http://theses.gla.ac.uk/1534/.
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A custom FES-cycling ergometer equipped with an electric motor and an integrated feedback system for accurate control of exercise workrate and cadence has been employed in this study. This experimental setup allowed the imposition of arbitrary workrate profiles with high precision and provided the potential for highly-sensitive exercise testing. One aim of the work described in this thesis was to propose and evaluate novel protocols for incremental exercise test (IET) and step exercise test (SET). Valid protocols would allow reliable estimation of the key markers of cardiopulmonary fitness in SCI subjects performing FES-cycling. Measures which can be used to evaluate the effect on cycling performance of changes in stimulation parameters, and which might therefore be used to optimise them, were also investigated. Thus, a second aim of this work was to determine whether oxygen uptake and a new measure of stimulation cost (i.e. the total rate of stimulation charge applied to the stimulated muscle groups during cycling) are sensitive enough to allow discrimination between the efficacy of different activation patterns during constant-power cycling. A discussion on the concept of metabolic efficiency in AB and SCI subjects is presented in this thesis. Efficiency of FES-cycling is much lower than that of voluntary cycling. Therefore, a third aim of this work was to define new efficiency measurements that are more appropriate for the SCI population. Two volunteer subjects took part in this study and the data obtained from the tests they performed are presented as case studies. The main outcome shows feasibility of the two exercise testing protocols. Moreover, the first report of a ventilatory threshold in SCI subjects during FES-cycling has been provided here. Oxygen uptake and stimulation cost measurements both allow discrimination between the efficacy of different muscle activation patterns. However, stimulation cost is more easily determined in real time, and responds more rapidly and with greatly improved signal-to-noise properties than oxygen uptake.
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Bazler, Anthony Lee II. "The Redesign of a Recumbent Tricycle Using a Crank Rocker Mechanism To Increase Power Throughput In FES Cycling". University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1607681055373292.
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Jafari, Ehsan. "Novel Approaches in Functional Electrical Stimulation for Rehabilitation : Development, Analysis, and Optimization". Electronic Thesis or Diss., Lyon, École normale supérieure, 2024. http://www.theses.fr/2024ENSL0008.
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Cette thèse vise à surmonter les limites de la stimulation électrique fonctionnelle (SEF) grâce à une approche novatrice et multimodale, qui explore aussi bien le développement d'électrodes transcutanées, que les stratégies de stimulation, ainsi que les perspectives d'optimisation biomécanique. Une première étude compare l'efficacité des électrodes textiles intégrées dans les vêtements, utilisées avec une lotion hydratante, par rapport aux électrodes conventionnelles à hydrogel auto-adhésives. L'évaluation porte sur des aspects tels que le confort de la stimulation, la cohérence temporelle, l'efficacité, et le comportement de l'impédance électrique dans des conditions isométriques. Les participants à l'étude ont effectué des tests avec les deux types d'électrodes, nous permettant d’évaluer des paramètres tels que les intensités minimales générant une contraction musculaire ou une sensation de brûlure, et l'intensité maximale tolérable. Les résultats indiquent que les électrodes textiles, lorsqu'elles sont complétées par une lotion, sont comparables aux électrodes à hydrogel en termes de confort, de consistance et d'efficacité. Une seconde étude examine l'impact de la stimulation séquentielle distribuée spatialement (SSDS) à intensité moyenne ou haute, sur la réduction de la fatigue chez les personnes souffrant d'une lésion de la moelle épinière. L'étude révèle que la SSDS est significativement plus efficace à moyenne intensité. En outre, une étude de cas a été réalisée pour évaluer les différences de puissance et fatigue produites lors d’un exercice de cyclisme électrostimulé utilisant la SSDS. Il s'agissait de stimuler les quadriceps de quatre participants paraplégiques moteurs complets. L’étude a montré que la SSDS génère non seulement plus de puissance que la configuration à une seule électrode, mais également sans avoir d'impact significatif sur le niveau de fatigue. La dernière étude se concentre sur l'optimisation des propriétés biomécaniques du cyclisme et de la séquence de stimulation afin d'obtenir une puissance de sortie maximale avec une stimulation appliquée minimale. Un modèle musculaire précis et facile à utiliser, associé à des fonctions de transfert de couple basées sur le Jacobien, a été adopté pour déterminer la position assise optimale, l'angle du tronc, la longueur du bras de manivelle et les séquences de stimulation. En outre, l'impact de la fonction force-vitesse du muscle sur la détermination de la position assise optimale et des séquences de stimulation a été étudié. Les modèles de simulation ont montré un effet insignifiant de la fonction force-vitesse sur la position assise optimale de six sujets sains simulés. Nous pensons que les contributions de cette thèse augmenteront l'efficacité de la SEF en tant que technique de rééducation fonctionnelleThis thesis aims to overcome the limitations of functional electrical stimulation (FES) through a multifaceted novel approach that concentrates on developing transcutaneous electrodes, stimulation strategies, and biomechanical optimization perspectives. The first study investigates the effectiveness of garment-embedded textile electrodes, used with a moisturizing lotion, against conventional self-adhesive hydrogel electrodes. The evaluation encompasses aspects such as stimulation comfort, temporal consistency, efficiency, and electrical impedance behavior under isometric conditions. Participants in the study underwent tests with both electrode types, evaluating parameters like motor threshold intensity, burning sensation intensity, and maximum tolerable intensity. The results indicate that textile electrodes, when supplemented with lotion, perform comparably to hydrogel electrodes in terms of comfort, consistency, and efficiency. The next study investigates the impact of spatially distributed sequential stimulation (SDSS) at high and moderate intensities on reducing fatigue in individuals with spinal cord injury. The study, focusing on the quadriceps muscle group, found that moderate-intensity SDSS is significantly more effective than high-intensity SDSS. Additionally, a case study was conducted to assess the differences in power generation and fatigue levels between FES cycling using SDSS and a single electrode setup. This involved stimulating the paralyzed quadriceps muscles of four participants over multiple days during motor-assisted FES cycling. The results indicated that SDSS not only generated more power compared to the single electrode setup but did so without significantly impacting fatigue levels. The last study focuses on the optimization of the cycling biomechanical properties and stimulation pattern to achieve maximum output power with minimum applied stimulation. In this work, an easy-to-use and precise muscle model in conjunction with Jacobian-based torque transfer functions was adopted to determine the optimal seating position, trunk angle, crank arm length, and stimulation intervals. Furthermore, the impact of muscle force-velocity factor in finding the optimal seating position and stimulation intervals was investigated. The simulation models showed the trivial effect of the force-velocity factor on the resulting optimal seating position of six healthy simulated subjects. We believe that the contributions of this thesis will increase the efficacy of FES as a rehabilitation technique
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Dag, Gabriel. "PHM Approaches for Reliability of ECUs : Analyses of Canaries and Real-Time Data Acquisition". Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-325974.
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Today, Scania CV AB is facing challenging demands on functionality and performance within their vehicles. The electronics are increasing rapidly and to stay competitive on the market, concerns regarding reliability of electronic systems needs to be evaluated. Prognostics and health management (PHM) is a concept where reliability of, for example, electronic control units (ECUs) are assessed. It requires customized systems for each specific environment, due to different strains and stresses. One approach is to have canaries (components with reduced soldering mass) implemented into ECUs as an indication that something is about to happen. Another essential aspect is the continuous real-time data acquisition from sensors, that can be used for different algorithms and models, which could provide forecasts on remaining useful life (RUL) of the ECUs. An appliance is the big data acquisition, where a database will collect data from vehicles, which means that ECU data need be communicated differently than today. This is why this master thesis project investigated canaries on printed circuit boards (PCBs) when they were subjected to vibrations as well as thermal cycling (TC), which are common parameters within vehicles. The PCBs consisted of both lead (Sn-Pb) and lead-free (SAC305) soldering for material comparison, since a transition to lead-free electronics is happening. Several fatigue tests were performed to collect as much information as possible. For further advances towards a PHM implementation, thermal shock (TS) tests on ECUs were performed as well. The ECUs were shocked in a temperature cabinet while being in active state. The internal temperature sensor was communicated with via controller area network (CAN). Scania’s CAN program was used and the data was logged in a computer, which in turn was compared to the data from the surrounding thermocouples, placed in specific spots. The results that were achieved clearly showed that lead-free PCBs are much more sensitive to stresses (both vibrations and TC). It was also shown that canaries failed in a much higher extent than regular resistors. The real-time data acquisition from the ECU could successfully be managed, where continuous data was logged. Also, the TS tests showed how the correlation between sensors indifferent positions was. Finally, the results from these tasks were discussed for future work. One have to keep in mind that this is just the beginning of a many-years project within Scania. The results and progress within this master thesis project will hopefully be a step in the rightdirection.
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Berry, Helen Russell. "Characterisation of cardiorespiratory responses to electrically stimulated cycle training in paraplegia". Thesis, Connect to e-thesis. Edited version, 2008. http://theses.gla.ac.uk/386/.
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Thesis (Ph.D.) - University of Glasgow, 2008.PhD. theses submitted to the Department of Mechanical Engineering, Faculty of Engineering, University of Glasgow. Edited version of thesis available, uncleared 3rd party copyright material removed. Includes bibliographical references. Print version also available.
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Rezza, Pasquale. "Mechanical and electrical performances of superconducting cables subject to cyclic stresses". Thesis, Massachusetts Institute of Technology, 1985. https://hdl.handle.net/1721.1/121907.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.Bibliography: leaves 89-91.
by Pasquale Rezza, Jr.
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.
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W, F. Yahya Doaa. "Mechanické a elektrické vlastnosti tenkých kovových vrstev nanášených vakuovým napařováním". Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-234574.
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Thin layers are widely used in many fields of technology and today we can say that they are found in all modern technologies. Thin layers can be created in two ways, namely by chemical or physical means. This work focuses on the latter method, more particularly a technology of thermal evaporation of thin layers in a vacuum. The work focuses on the process principles during and after the evaporation. Much of the work focuses on the development and design of experiments. These experiments illustrate some of the phenomena that take place on thin films produced by the aforementioned technology. Work helps to better understand processes during formation of thin layers and properties that influence the quality and stability of thin films. In conclusion we describe results of experiments and new developments in the field of thin films deposition using evaporation under vakuum are summarized.
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Cairns, Sally, Frauke Behrendt, David Raffo, C. Beaumont e C. Kiefer. "Electrically-assisted bikes: Potential impacts on travel behaviour". Elsevier, 2017. https://publish.fid-move.qucosa.de/id/qucosa%3A72811.
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This paper reports on a review of the European literature about the impacts of having an electrically-assisted bike available to use, together with results from a trial in the UK city of Brighton, where 80 employees were loaned an electrically-assisted bike for a 6–8 week period. In the Brighton trial, three-quarters of those who were loaned an e-bike used them at least once a week. Across the sample as a whole, average usage was in the order of 15–20 miles per week, and was accompanied by an overall reduction in car mileage of 20%. At the end of the trial, 38% participants expected to cycle more in the future, and at least 70% said that they would like to have an e-bike available for use in the future, and would cycle more if this was the case. This is consistent with the results of the European literature which shows that when e-bikes are made available, they get used; that a proportion of e-bike trips typically substitutes for car use; and that many people who take part in trials become interested in future e-bike use, or cycling more generally.
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Eisel, Thomas. "Cooling of electrically insulated high voltage electrodes down to 30 mK". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-77442.
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The Antimatter Experiment: Gravity, Interferometry, Spectroscopy (AEGIS) at the European Organization for Nuclear Research (CERN) is an experiment investigating the influence of earth’s gravitational force upon antimatter. To perform precise measurements the antimatter needs to be cooled to a temperature of 100 mK. This will be done in a Penning trap, formed by several electrodes, which are charged with several kV and have to be individually electrically insulated. The trap is thermally linked to a mixing chamber of a 3He-4He dilution refrigerator.
Two link designs are examined, the Rod design and the Sandwich design. The Rod design electrically connects a single electrode with a heat exchanger, immersed in the helium of the mixing chamber, by a copper pin. An alumina ring and the helium electrically insulate the Rod design. The Sandwich uses an electrically insulating sapphire plate sandwiched between the electrode and the mixing chamber. Indium layers on the sapphire plate are applied to improve the thermal contact. Four differently prepared test Sandwiches are investigated. They differ in the sapphire surface roughness and in the application method of the indium layers.
Measurements with static and sinusoidal heat loads are performed to uncover the behavior of the thermal boundary resistances. The thermal total resistance of the best Sandwich shows a temperature dependency of T-2,64 and is significantly lower, with roughly 30 cm2K4/W at 50 mK, than experimental data found in the literature. The estimated thermal boundary resistance between indium and sapphire agrees very well with the value of the acoustic mismatch theory at low temperatures.
In both designs, homemade heat exchangers are integrated to transfer the heat to the cold helium. These heat exchangers are based on sintered structures to increase the heat transferring surface and to overcome the significant influence of the thermal resistance (Kapitza resistance). The heat exchangers are optimized concerning the adherence of the sinter to the substrate and its sinter height, e.g. its thermal penetration length.
Ruthenium oxide metallic resistors (RuO2) are used as temperature sensors for the investigations. They consist of various materials, which affect the reproducibility. The sensor conditioning and the resulting good reproducibility is discussed as well.
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Luedtke, Elin. "Minimizing Transformer No-Load Losses at Hydropower Plants : A Study of Effects from Transformer Switch-Off During Stand-by Operation". Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-447635.
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Hydropower is the most important power balancing resource in the Swedish electrical power system, regulating the power supply to match the load. Consequently, several hydropower plants have periods of stand-by operation where the power production is absent but where several devices within a plant are still active. Such a device is the step-up power transformer, which during stand-by operation still generates no-load energy losses. These losses can accumulate to a considerable amount of energy and costs during the long technical lifetime of the apparatus. One option to minimize these no-load energy losses is by turning the transformer off when its generating unit is in stand-by operation. However, when this transformer operational change has been explained to experts in the field, the most common response has been that a more frequent reenergizing of a transformer leads to higher risks for errors or transformer breakdowns. This study aimed to analytically investigate three effects from this operational change. First, the potential of fatigue failure for the windings due to the increased sequences of inrush current. Secondly, the thermal cycling as a consequence of change in present losses. Lastly, the energy and economic saving potentials for hydropower plants where this operational adjustment is applied. The study used both established as well as analytical tools explicitly created for this study. These were then applied on currently active transformers in different plant categories in Fortum’s hydropower fleet. The study primarily showed three things. Firstly, risk of fatigue failure due to the increased presence of inrush currents did not affect the transformer’s technical lifetime. Secondly, the thermal cycling changes were slightly larger with absent no-load losses during stand-by operation. The average temperature for the transformer decreased, which in general is seen as a positive indicator for a longer insulation lifetime and thus the transformer’s technical lifetime. Finally, the created frameworks showed the potential of saving energy and money for all plant categories, where the potential grew with the installed production capacity and the stand-by operation timeshare. Despite the simplifications made to describe the complex reality of a transformer operating in a hydropower plant, this thesis contributes to lay a foundation for future investigation of an easy adjustment to avoid unnecessary energy losses and costs for transformers in hydropower plants.
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Miah, Shahjahan. "A low-cost intelligent localisation system to improve cyclist safety". Thesis, City, University of London, 2018. http://openaccess.city.ac.uk/19873/.
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Cycling is an increasingly popular mode of travel in cities owing to the great advantages that it offers in terms of space consumption, health and environmental sustainability, and it is therefore favoured and promoted by many city authorities worldwide. A large number of recently introduced cycling-related schemes in many cities demonstrates this trend. However, the relatively low safety of pedal cycles as perceived by the users currently presents itself as a hurdle, and therefore cycling has yet to be adopted to a wider extent by users as a true alternative to the private car. Rising accident numbers, unfortunately, confirm this perception as reality, with a particular source of hazard appearing to originate from the interaction of cyclists with motorised traffic at low speeds in urban areas. Technological advances in recent years have resulted in a number of attempts to develop systems to prevent cyclist-vehicle collisions, but they have generally stumbled upon the challenge of accurate cyclist localisation and tracking, which can enable predicting a collision within a short-term time-horizon (5-10 seconds). Indeed, cyclist positioning accuracy is essential for any collision avoidance system, not only to ensure the effective operation of the system but also to minimise the occurrence of false alerts. Thus, motivated by the poor safety record, the research reported here involves the development and testing of an innovative technological solution for accurately localising and tracking cyclists, where the ultimate aim is to utilise the techniques in a concept called Cyclist 360° Alert to avoid collisions. The overarching innovation of this PhD is the development of the instrumented bicycle system, called iBike, which can be employed to track cyclists’ positions more precisely. The system relies on bicycles being instrumented with low-cost Micro-electromechanical systems (MEMS) sensors, and utilises multiple Kalman filters, which were developed from the geometrical and kinematics modelling of the bicycles, to conduct a multi-sensor fusion on the iBike acquisition data with the measurements from the Global Positioning System, Wi-Fi hotspots and mobile communication systems. Apart from the above, the thesis also reports on the results obtained from a number of field trials where an enhanced off-the-shelf positioning system was employed to validate the developed system. The overall results from the field experiments demonstrate that, on average with an 80% probability, the iBike system can be used to estimate a position with less than 0.5 m error compared to a 16.2 m error from the enhanced positioning system under the same circumstances. Thus, the results from the field trials using the iBike have shown successful outcomes for the developed methodologies. This means that the iBike can be used to predict a collision more precisely. These results are presented in detail together with the hardware and software of the iBike system in this thesis.
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Thirathon, Nattavude 1980. "Cyclic exchange neighborhood search technique for the K-means clustering problem". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17981.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 151-152).
Cyclic Exchange is an application of the cyclic transfers neighborhood search technique for the k-means clustering problem. Neighbors of a feasible solution are obtained by moving points between clusters in a cycle. This method attempts to improve local minima obtained by the well-known Lloyd's algorithm. Although the results did not establish usefulness of Cyclic Exchange, our experiments reveal some insights on the k-means clustering and Lloyd's algorithm. While Lloyd's algorithm finds the best local optimum within a thousand iterations for most datasets, it repeatedly finds better local minima after several thousand iterations for some other datasets. For the latter case, Cyclic Exchange also finds better solutions than Lloyd's algorihtm. Although we are unable to identify the features that lead Cyclic Exchange to perform better, our results verify the robustness of Lloyd's algorithm in most datasets.
by Nattavude Thirathon.
M.Eng.
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Chuang, Eugene (Eugene Yu) 1975. "Cyclic load resistance of reinforced concrete beams retrofitted with composite laminates". Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47496.
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Leitholf, Andrew M. "Iron Cycling In Microbially Mediated Acid Mine Drainage Derived Sediments". University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1434976163.
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Guidry, Michael J. (Michael James) 1976. "A 16-bit, 100kS/s self-calibrating cyclic analog-to-digital converter". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9075.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (leaf 50).
Self-calibrating AID architectures minimize the sometimes expensive process of in-factory calibration, thus allowing manufacturers to reduce chip cost. This thesis presents an AID converter built using one such architecture, the reference-refreshing architecture. This converter shows under simulation 100 kHz performance at 16 bits, with INL of 1.2 LSBs, SNR of 89 dB, and power consumption of 170 mW.
by Michael J. Guidry.
M.Eng.
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Roham, Masoud. "Wireless Multichannel Microsystems for Time-Share Chemical and Electrical Neural Recording". Cleveland, Ohio : Case Western Reserve University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1258145434.
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Thesis(Ph.D.)--Case Western Reserve University, 2010Title from PDF (viewed on 2009-12-30) Department of Electrical Engineering and Computer Science Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center
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Roumy, Laurane. "Study of the Electro-Thermo-Mechanical Behaviour of a 4D Printed Actuator". Electronic Thesis or Diss., Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2024. http://www.theses.fr/2024ESMA0016.
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L’objectif de ce travail de thèse était de développer une charnière électrosensible en se basant sur l’impression 4D. Il s’agit d’utiliser une méthode de fabrication additive couplée à un matériau intelligent sensible à un stimulus externe dans le but de créer un mouvement, la quatrième dimension étant le temps. Pour cette étude, le stimulus externe est la température, et l’échauffement est obtenu par effet Joule. L’impression par Fused Filament Fabrication (FFF) qui permet la création d’une structure tridimensionnelle par le dépôt de filaments de polymère fondu a été choisie pour son coût peu élevé, son utilisation aisée, et la production quasi inexistante de déchets. L’acide polylactique (PLA) a été utilisé car il possède d’excellentes capacités de mémoire de forme, est biosourcé, produit en Europe et souvent utilisé en FFF. Dans le but de pouvoir le chauffer par effet Joule, du PLA renforcé par des particules de noir de carbone (CB/PLA) a été considéré. Un matériau thermosensible chauffable à distance par un circuit électrique est ainsi obtenu. Une analyse des couplages électrothermique et électromécanique dans ce matériau a donc été menée. Une première étape a consisté à maîtriser le lien entre les propriétés de l’éprouvette imprimée et les paramètres d’impression. Des éprouvettes rectangulaires ont ensuite été chauffées par effet Joule et observées par caméra thermique dans le but d’étudier le comportement du matériau soumis à trois créneaux de voltages différents. Un modèle basé sur l’équation de la chaleur a été mis en place afin de prévoir les températures atteintes au sein du matériau. Suite à un cyclage électrique, une modification de la microstructure du CB/PLA engendrant une évolution de la résistance électrique a été mise en évidence. Une étude du couplage électromécanique a ensuite été réalisée via des essais de traction monotone et cyclée afin d’analyser l’évolution de la résistance électrique sous sollicitation mécanique et dans le cadre d’une utilisation répétée. Les avantages d’une structure avec un angle d’impression longitudinal par rapport à l’axe de sollicitation ont été mis en évidence par des propriétés électriques et mécaniques supérieures et une meilleure durabilité. D’autres angles d’impression ont également été testés et la théorie des stratifiés a pu être appliquée aux éprouvettes imprimées 3D. Un suivi des endommagements dans les éprouvettes de traction a été mené par émission acoustique et par des observations au microscope électronique à balayage et au micro tomographe. Le développement de craquelures perpendiculaires à l’axe de sollicitation a été mis en évidence. Finalement, une charnière a été conçue et testée pour un angle de pliage de 90°. Une optimisation des paramètres d’impression a été conduite afin de réduire l’influence des contraintes résiduelles dues au procédé de fabrication lors de la phase d’apprentissage de la charnière. Les résultats ont montré l’influence prépondérante de la température du plateau et de la vitesse d’impression. Le déploiement reproductible d’une charnière avec environ 80% de taux de recouvrement a été obtenu, et la force déployée ainsi que la vitesse de déploiement ont été mesurées. L’utilisation répétée d’une telle charnière et sa durabilité ont été investiguées en réalisant dix cycles successifs de déploiement. L’influence de la température de programmation et d’actionnement a été également étudiée. Finalement, une ébauche de charnière réversible a été proposée. Il a ainsi été démontré qu’il est possible de créer un prototype optimisé de charnière activable par effet Joule, à distance, par impression 4DThe aim of this thesis was to develop an electro sensitive 4D printed hinge. 4D printing consists in using an additive manufacturing method coupled with an intelligent material that is sensitive to an external stimulus in order to create movement, the fourth dimension being time. For this study, the external stimulus is temperature, and heating is achieved by the Joule effect. Fused Filament Fabrication (FFF), which creates a three-dimensional structure by depositing melted polymer filaments, was chosen for its low cost, ease of use and low waste production. Polylactic acid (PLA) was used because it has excellent shape memory properties, is biosourced, is produced in Europe and is often used in FFF. To use the Joule effect, PLA reinforced with carbon black particles (CB/PLA) was considered. The result is a heat-sensitive material that can be heated remotely via an electrical circuit. An analysis of the electro-thermal and electro-mechanical couplings in this material was therefore carried out. The first step was to establish the link between the properties of the printed sample and the printing parameters. Rectangular specimens were then heated using the Joule effect and observed with a thermal camera in order to study the behaviour of the material when subjected to three different voltages. A model based on the heat equation was used to predict the temperatures reached within the material. Under electrical cycling, a change in the CB/PLA microstructure was observed, resulting in a change in electrical resistance. A study of the electro-mechanical coupling was then carried out using monotonic and cyclic tensile tests to analyse changes in electrical resistance under mechanical stress and in the context of repeated use. The advantages of a structure with a longitudinal printing angle, along the loading direction, were demonstrated by superior electrical and mechanical properties and improved durability. Other printing angles were also tested and the classical laminate theory was applied to the 3D printed specimens. Damage in the tensile specimens was monitored using acoustic emission, scanning electron microscopy and micro computed tomography. The development of crazes perpendicular to the loading direction was demonstrated. Finally, a hinge was designed and tested for a bending angle of 90°. The printing parameters were optimised to reduce the influence of residual stresses due to the manufacturing process during the programming step of the hinge. The results showed that the temperature of the plate and the printing speed had a noticeable influence. The reproducible deployment of a hinge with approximately 80% of recovery was obtained, and the force deployed and the deployment speed were measured. The repeated use of such a hinge and its durability were investigated by carrying out ten successive deployment cycles. The influence of programming and triggering temperatures was also studied. Finally, a first approach of reversible hinge was proposed. It was thus demonstrated that it is possible to create an optimised prototype of a 4D printed hinge that can be remotely triggered by Joule effect
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Westram, Ilona [Verfasser]. "Crack Propagation in Pb(Zr,Ti)O3 under Cyclic Electric Loading / Ilona Westram". Aachen : Shaker, 2006. http://d-nb.info/1166508366/34.
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Popp, Matthias H. "Design and construction of a laboratory system for neuromuscular stimulation of the lower extremities during cycling". Master's thesis, University of Cape Town, 1986. http://hdl.handle.net/11427/27211.
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Functional Neuromuscular Stimulation (FNS) is a method by which paralyzed muscles are stimulated electrically in order to produce a useful movement. The design and testing of a laboratory system for the modulated control of the lower extremities during FNS-induced cycling on an exercising device (Paracycle) is described. The system hardware, which is designed around a standard IBM compatible Personal Computer, features six independent stimulation channels. Waveform characteristics such as pulse frequency, width and amplitude are defined as a function of the crank position of the Paracycle for each channel. An extensive software package allows programmability of the waveform parameters and supports the user in the definition of stimulation sequences. The effective performance of the complete FNS-controller/ Paracycle system has been demonstrated during a controlled case study with two paraplegic subjects.
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Guenther, Brent Edward. "Multi-User Signal Classification Via Cyclic Spectral Analysis". Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1288490195.
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Nugues, Samuel. "Mesure de l'état de charge d'une batterie par coulométrie corrigée par impédancemétrie". Grenoble INPG, 1996. http://www.theses.fr/1996INPG0144.
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Les systemes actuels de mesure de l'etat de charge d'une batterie ne permettent pas de connaitre de maniere fiable l'energie restante dans un accumulateur. Le premier chapitre detaille le fonctionnement electrotechnique des batteries de traction au nickel-cadmium, presente une modelisation electrique de ces dernieres, explicite le principe de mesure par coulometrie et enfin justifie l'interet de la mesure d'impedance. Dans une deuxieme partie, les bancs de mesure necessaires a l'experimentation relative aux mesures d'impedance sont presentes: banc de mesure d'impedance proprement dit, banc de cyclage permettant la decharge des batteries suivant un cycle qui simule le roulage d'un vehicule et sa recharge. Le troisieme chapitre traite de la methodologie de mesure de l'impedance que nous avons pris soin de definir afin de garantir la fiabilite et la reproductibilite des mesures. Dans la derniere partie, nous interpretons les nombreuses mesures realisees des parties reelle et imaginaire de l'impedance afin d'en deduire des conditions de mesure permettant de connaitre l'etat de charge avec precision et avec un minimum d'experimentations. Nous presentons pour finir les differentes associations pouvant etre envisagees entre la coulometrie et l'impedancemetrie pour realiser une jauge d'energie
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Alkan, Cemil. "Synthesis, Characterization And Electrical Properties Of Diazophenylene And Diazodiphenylene Bridged Co, Ni, Cu, Ce, And Er Phthalocyanine Polymers". Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605362/index.pdf.
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SYNTHESIS, CHARACTERIZATION, AND ELECTRICAL PROPERTIES OF DIAZOPHENYLENE AND DIAZODIPHENYLENE BRIDGED Co, Ni, Cu, Ce, AND Er PHTHALOCYANINE POLYMERS
Alkan, Cemil
M. Sc., Department of Polymer Science and Technology
Supervisor: Prof.Dr. Leyla Aras
Co- Supervisor: Prof.Dr. Güngö
r Gü
ndü
z September 2004, 112 pages In this research, diazophenylene and diazodiphenylene bridged metal-phthalocyanine polymers were produced from diazonium salt of diaminophenylene/bensidin and pre-synthesized tetraamino metal phthalocyanines. Tetraamino metal phthalocyanine complexes of Co, Ni, Cu, Ce, and Er were obtained by reducing tetranitro metal phthalocyanine complexes synthesized from 3-nitrophthalic anhydride, urea, metal salt, and ammonium molybdate catalyst. Complexes and polymers were characterized by Fourier Transform Infrared Radiation (FTIR) and UV-Visible spectroscopies. X-Ray analysis showed that there were short range orientations in the polymers. Thermal analysis of the complexes and the polymers were done by differential scanning calorimetry and thermal gravimetric analysis at a heating rate of 10&
#61616
Cmin&
#61485
1 under nitrogen atmosphere. Ash analysis was performed to determine the metal content of the polymers. Viscosity and ebullioscopy measurements of the soluble part of the polymers were carried out in THF at 25&
#61616
C. Scanning electron microscopy were used for morphology investigations of the polymers. Four probe conductivity measurements showed that electrical conductivity of the polymers increased according to the metallic conductivity of the metal at the center of the phthalocyanine units. When doped with iodine, the polymer samples showed 104 fold increase in their conductivities. Current-Voltage (I-V) measurements showed that the polymers were optically sensitive and semiconductors. Electrochemical analysis of the soluble part of the polymers were determined in tributylamine perchlorite+dichloromethane mixture utilizing cyclic voltammetry (CV).
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Said, Faozi. "An Evaluation of QuikSCAT UHR Wind Product's Effectiveness in Determining Selected Tropical Cyclone Characteristics". Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3269.pdf.
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Dozza, Marco, Piccinini Giulio Francesco Bianchi e Julia Werneke. "Using naturalistic data to assess e-cyclist behavior". Elsevier, 2015. https://publish.fid-move.qucosa.de/id/qucosa%3A72822.
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In Europe, the use of electric bicycles is rapidly increasing. This trend raises important safety concerns: Is their use compatible with existing infrastructure and regulations? Do they present novel safety issues? How do they impact other traffic? This study sought to address these concerns, using instrumented electric bicycles to monitor e-cyclists’ behavior in a naturalistic fashion. Data was collected from 12 bicyclists, each of whom rode an instrumented bicycle for two weeks. In total, 1500 km worth of data were collected, including 88 critical events (crashes and near-crashes). Analysis of these critical events identified pedestrians, light vehicles and other bicycles as main threats to a safe ride. Other factors also contributed to crash causation, such as being in proximity to a crossing or encountering a vehicle parked in the bicycle lane. A comparison between electric and traditional bicycles was enabled by the availability of data from a previous study a year earlier, which collected naturalistic cycling data from traditional bicycles using the same instrumentation as in this study. Electric bicycles were found to be ridden faster, on average, than traditional bicycles, in addition to interacting differently with other road users. The results presented in this study also suggest that countermeasures to bicycle crashes should be different for electric and traditional bicycles. Finally, increasing electric bicycle conspicuity appears to be the easiest, most obvious way to increase their safety.
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Robbins, Jesse. "An Investigation into the Cyclic Electric Fatigue of Ferroelectric Ceramics as Actuators: High Temperature and Low Pressure". University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1240861885.
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Robbins, Jesse H. "An investigation into the cyclic electric fatigue of ferroelectric ceramics as actuators high temperature and low pressure /". Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1240861885.
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Thesis (M.S.)--University of Akron, Dept. of Mechanical Engineering, 2009."May, 2009." Title from electronic thesis title page (viewed 8/2/2009) Advisor, Celal Batur; Co-advisor, Ali Sayir; Committee member, Jiang Zhe; Department Chair, Celal Batur; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Pal, Chandana. "Thin films of non-peripherally substituted liquid crystalline phthalocyanines A". Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/8997.
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Three non-peripherally substituted liquid crystalline bisphthalocyanine (Pc) compounds have been studied to examine the role of central metal ions lutetium (Lu), and gadolinium (Gd) and substituent chain lengths, i.e. octyl (C8H17) and hexyl (C6H13), in determining the physical properties. For the octyl substituted Pc molecules, the head-to-tail or Jaggregates within the as-deposited spun films produced a redshift of the optical absorption Q bands in relation to their 0.01 mgml-1 solutions. Annealing at 80˚C produced a well-ordered discotic liquid crystalline (LC) mesophase causing additional redshifts irrespective of the metal ion in case of C8LuPc2 and C8GdPc2. Formation of face-to-face or H-aggregated monomers led to blueshifts of the Q bands with respect to solution spectra for C6GdPc2, both as-deposited and annealed films. Stretching and bending vibrations of pyrrole, isoindole, and metal-nitrogen bonds in Pc rings showed Raman bands at higher energy for smaller metal ion. However, no change was observed for the difference in chain lengths. As-deposited C8LuPc2 and C6GdPc2 produced comparable Ohmic conductivity, of the value 67.55 Scm-1 and 42.31 Scm-1, respectively. C8GdPc2 exhibited two orders of magnitude less conductivity than the other two due to the size effect of the central ion and side chain length. On annealing, an increase of Ohmic conductivity was noticed in the isostructural octyl substituted phthalocyanines on contrary to a reduced conductivity in hexyl substituted one. An optical band shift of the C8LuPc2 and C8GdPc2 thin films occurred on oxidation by bromine vapour. Oxidations of Pc-coated ITO were also achieved by applying potential at 0.88 V and 0.96 V electrochemically for the C8LuPc2 and C8GdPc2 compounds, respectively. To explore the applications of these compounds in biosensing, in situ interaction studies between bromine oxidised compounds and biological cofactors nicotinamide adenine dinucleotide (NADH) and L-ascorbic acid (vitamin C) were carried out using optical absorption spectroscopy. Thin films of a non-peripherally octyl substituted LC lead phthalocyanine was exposed to 99.9 % pure hydrogen sulfide gas to produce hybrid nanocomposites consisting of lead sulphide quantum dots embedded in the analogous metal free phthalocyanine matrix. Trapping of charge carriers caused hysteresis in the current-voltage characteristics of the film on interdigitated gold electrodes. The charge hopping distance was found to be 9.05 nm, more than the percolation limit and responsible for forming two well-defined conducting states with potential application as a memristor.
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Thakur, Ravi Bhushan. "Low power design implementation of a signal acquisition module". Thesis, Kansas State University, 2010. http://hdl.handle.net/2097/4617.
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Master of ScienceDepartment of Electrical and Computer Engineering
Don M. Gruenbacher
As semiconductor technologies advance, the smallest feature sizes that can be fabricated get smaller. This has led to the development of high density FPGAs capable of supporting high clock speeds, which allows for the implementation of larger more complex designs on a single chip. Over the past decade the technology market has shifted toward mobile devices with low power consumption at or near the top of design considerations. By reducing power consumption in FPGAs we can achieve greater reliability, lower cooling cost, simpler power supply and delivery, and longer battery life. In this thesis, FPGA technology is discussed for the design and commercial implementation of low power systems as compared to ASICs or microprocessors, and a few techniques are suggested for lowering power consumption in FPGA designs. The objective of this research is to implement some of these approaches and attempt to design a low power signal acquisition module. Designing for low power consumption without compromising performance requires a power-efficient FPGA architecture and good design practices to leverage the architectural features. With various power conservation techniques suggested for every stage of the FPGA design flow, the following approach was used in the design process implementation: the switching activity is addressed in the design entry, and synthesis level and software tools are utilized to get an initial estimate of and optimize the design’s power consumption. Finally, the device choice is made based on its features that will enhance the optimization achieved in the previous stages; it is configured and real time board level power measurements are made to verify the implementation’s efficacy
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Indeir, Fahima. "Development of an advanced DC-polarisation/AC-impedance cyclic test to evaluate the corrosion of electrically-conductive coating/substrate systems". Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/17935/.
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In this work, an advanced (AC)DC/OCP/AC cyclic test regime has been developed (and validated experimentally) as a new tool for the evaluation of the corrosion behaviour of metallic substrates and/or electrically-conductive coatings. Incorporation of concurrent solution pH measurement with the advanced (AC)DC/OCP/AC technique developed in this work, qualifies this approach to be applied in different industrial applications, such as in aircraft, nuclear and biomedical sectors. It provides opportunities to evaluate objectively the detailed corrosion behaviour in shorter exposure times (as little as 1 day) compared to the widely-used and accepted (but highly subjective) salt spray test (SST) and to conventional (periodically repeated but laborious) electrochemical impedance spectroscopy (EIS) evaluation at open circuit potential (EOCP). The (AC)DC/OCP/AC cyclic test provides valuable information concerning the corrosion behaviour of uncoated Al 6082 alloy (repeat tests are performed, to eliminate test protocol variables and improve the robustness of the test). The three examples of prototype PVD Al-based nanostructured coatings (AlCr, AlCr(N) and AlCrTi), deposited on 17/4 PH steel, were then evaluated from a scientific perspective, to acquire a fundamental understanding of their performance and degradation with time. The results are shown in two main sets; i) electrochemical results obtained at EOCP and six repeated cycles of (AC)DC/OCP/AC cyclic testing and ii) solution pH results during continuous monitoring of the cyclic electrochemical test procedure. AlCrTi coating showed the best corrosion resistance after application of six successive DC/OCP cycles as a sacrificial protection for the substrate, followed by the AlCr(N) and AlCr coatings. However, the repassivation behaviour exhibited by the AlCr(N) coating after breakdown during extreme DC polarisation, may suggest an advantage to use this coating preferably in aerospace applications because of its strong ability to self-heal. This might be promising for future coating materials for corrosion protection where cadmium or hard chromium needs to be replaced. In addition, the structural and chemical composition of these samples was characterised using SEM and EDX analysis. Conventional open circuit potential (EOCP) and potentiodynamic polarisation scans were also employed, to determine the ‘as-received’ corrosion behaviour.
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Choudhury, Noor. "Reliability prediction of electronic products combining models, lab testing and field data analysis". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202594.
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At present there are different reliability standards that are being used for carrying out reliability prediction. They take into consideration different factors, environments and data sources to give reliability data for a wide range of electronic components. However, the users are not aware of the differences between the different reliability standards due to the absence of benchmarks of the reliability standards that would help classify and compare between them. This lack of benchmark denies the users the opportunity to have a top-down view of these different standards and choose the appropriate standard based on qualitative judgement in performing reliability prediction for a specific system. To addres this issue, the benchmark of a set of reliability standards are developed in this dissertation. The benchmark helps the users of the selected reliability standards understand the similarities and differences between them and based on the evaluation criterion defined can easily choose the appropriate standard for reliability prediction in different scenarios. Theoretical reliability prediction of two electronic products in Bombardier is performed using the standards that have been benchmarked. One of the products is matured with available incident report from the field while the other is a new product that is under development and yet to enter in service. The field failure data analysis of the matured product is then compared and correlated to the theoretical prediction. Adjustment factors are then derived to help bridge the gap between the theoretical reliability prediction and the reliability of the product in field conditions. Since the theoretical prediction of the product under development could not be used to compare and correlate any data due to unavailability, instead, the accelerated life test is used to find out the product reliability during its lifetime and find out any failure modes intrinsic to the board. A crucial objective is realized as an appropriate algorithm/model is found in order to correlate accelerated test temperature-cycles to real product temperature-cycles. The PUT has lead-free solder joints, hence, to see if any failures occurring due to solder joint fatigue has also been of interest. Additionally, reliability testing simulation is a performed in order to verify and validate the performance of the product under development during ALT. Finally, the goal of the thesis is achieved as separate models are proposed to predict product reliability for both matured products and products under development. This will assist the organization in realizing the goal of predicting their product reliability with better accuracy and confidence.För närvarande finns det olika tillförlitlighetsstandarder som används för att utföra tillförlitlighet förutsägelse. De tar hänsyn till olika faktorer, miljöer och datakällor för att ge tillförlitlighetsdata för ett brett spektrum av elektronikkomponenter. Men användarna inte är medvetna om skillnaderna mellan de olika tillförlitlighetsstandarder på grund av avsaknaden av riktmärken för tillförlitlighetsstandarder som skulle hjälpa klassificera och jämföra mellan dem. Denna brist på jämförelse förnekar användarna möjlighet att få en top-down bakgrund av dessa olika standarder och välja lämplig standard baserad på kvalitativ bedömning att utföra tillförlitlighet prognos för ett specifikt system. För att lösa detta problem, är riktmärket en uppsättning av tillförlitlighetsstandarder som utvecklats i denna avhandling. Riktmärket hjälper användarna av de utvalda tillförlitlighetsstandarder förstå likheter och skillnader mellan dem och på grundval av bedömningskriteriet definieras kan enkelt välja lämplig standard för pålitlighet förutsägelse i olika scenarier. Teoretisk tillförlitlighet förutsäga två elektroniska produkter i Bombardier utförs med hjälp av standarder som har benchmarking. En av produkterna är mognat med tillgängliga incidentrapport från fältet, medan den andra är en ny produkt som är under utveckling och ännu inte gå in i tjänsten. Analysen av den mognade produkten fält feldata jämförs sedan och korreleras till den teoretiska förutsägelsen. Justeringsfaktorer sedan härledas för att överbrygga klyftan mellan den teoretiska tillförlitlighet förutsägelse och tillförlitligheten av produkten i fältmässiga förhållanden. Eftersom den teoretiska förutsägelsen av produkt under utveckling inte kan användas för att jämföra och korrelera alla data på grund av otillgängligheten, i stället är det accelererade livslängdstest som används för att ta reda på produktens tillförlitlighet under dess livstid och reda ut eventuella felmoder inneboende till styrelsen . Ett viktigt mål realiseras som en lämplig algoritm /modell finns i syfte att korrelera accelererade provningen temperaturcykler på verkliga produkttemperatur cykler. PUT har blyfria lödfogar därmed att se om några fel inträffar på grund av löda gemensam trötthet har också varit av intresse. Dessutom är tillförlitlighet testning simulering en utförs för att verifiera och validera produktens prestanda under utveckling under ALT. Slutligen är målet med avhandlingen uppnås som separata modeller föreslås att förutsäga produktens tillförlitlighet för både förfallna och produkter under utveckling. Detta kommer att hjälpa organisationen att förverkliga målet att förutsäga deras tillförlitlighet med bättre noggrannhet och förtroende.
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SWANSON, DALE DORSETT. "ELECTROCHEMICAL AND SPECTROSCOPIC STUDIES OF THIOETHER COORDINATION COMPLEXES (CYCLIC VOLTAMMETRY, OCTAHEDRAL LOW-SPIN METALS, BLUE COPPER PROTEINS, ELECTRON PARAMAGNETIC RESONANCE)". Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188102.
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The bis 1,4,7-trithiacyclononane (1,4,7-TTCN) complexes of iron, cobalt, nickel and copper are reported in this work. Their properties have been examined using computer-controlled electrochemical and spectroscopic techniques. These TTCN complexes form readily, are unusually symmetrical and support electron transfer reactions at the metal center. The cobalt(II) complex is octahedral, low spin and symmetrical. Four oxidation states of cobalt-TTCN complex are observed; two one-electron transfer processes are reversible. Copper (II) bis 1,4,7-TTCN is unusually symmetrical evidenced by both solid phase and ambient temperature aqueous phase electron paramagnetic resonance spectra. An unusually high redox potential for the copper complex indicates extraordinary stability of the Cu(I) oxidation state but evidently not at the expense of Cu(II) stability. The complex also has a high formation constant compared to other copper-thioether complexes. This unusual strength of thioether donor is attributed to ligand geometry. The 1,4,7-TTCN molecule is the only known cyclic polythioether to have all sulfur atoms endodentate. This structure contributes to thermodynamic stability of complexes as the ground state configuration of the free ligand is maintained in the complex.
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Moncoľ, Maroš. "Uhlíkové elektrody pro superkondenzátory". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218318.
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This master thesis deals with supercapacitors based on electrical double layer and proper carbon electrodes for this type of supercapacitors. In theoretical part of work is described theory of supercapacitors, energy storage principles and their properties. In the next part are described carbon materials, their properties and electrochemical methods of measurements that we used. In the experimental part is described preparation of electrodes, results and conclusion.