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Adaptive neural network tracking control for underactuated systems with matched and mismatched disturbances
Get PDFThis paper studies neural network-based tracking control of underactuated systems with unknown parameters and with matched and mismatched disturbances. Novel adaptive control schemes are proposed with the utilization of multi-layer neural networks, adaptive control and variable structure strategies to cope with the uncertainties containing approximation errors, unknown base parameters and time-varying matched and mismatched external disturbances. Novel auxiliary control variables are designed to establish the controllability of the non-collocated subset of the underactuated systems. The approximation errors and the matched and mismatched external disturbances are efficiently counteracted by appropriate design of robust compensators. Stability and convergence of the time-varying reference trajectory are shown in the sense of Lyapunov. The parameter updating laws for the designed control schemes are derived using the projection approach to reduce the tracking error as small as desired. Unknown dynamics of the non-collocated subset is approximated through neural networks within a local region. Finally, simulation studies on an underactuated manipulator and an underactuated vibro-driven system are conducted to verify the effectiveness of the proposed control schemes
Computer-aided methods for single stage fibrous dysplasia excision and reconstruction in the zygomatico-orbital complex
Get PDFComputer Aided Design and Additive Manufacture (CAD/AM) technologies are sufficiently refined and meet
the necessary regulatory requirements for routine incorporation into the medical field, with long-standing
application in surgeries of the maxillofacial and craniofacial region. They have resulted in better medical care
for patients, and faster, more accurate procedures. Despite ever-growing evidence about the advantages of
computer aided planning, CAD and AM in surgery, detailed reporting on critical design decisions that enable
methodological replication, and the development and establishment of guidelines to ensure safety, are limited.
This paper presents a novel application of CAD and AM to a single stage resection and reconstruction of fibrous
dysplasia in the zygoma and orbit. It is reported in sufficient fidelity to permit methods replication and design
guideline developments in future cases, wherever they occur in the world. The collaborative approach included
engineers, designers, surgeons and prosthetists to design patient-specific cutting guides and a custom implant.
An iterative design process was used, until the desired shape and function were achieved, for both of the
devices. The surgery followed the CAD plan precisely and without problems. Immediate post-operative
subjective clinical judgements were of an excellent result.
At 19 months post-op, a CT scan was undertaken to verify the clinical and technical outcomes. Dimensional
analysis showed maximum deviation of 4.73 mm from the plan to the result, while CAD-Inspection showed that
the deviations range between -0.1 and -0.8 mm, and that the majority of deviations are located around the –0.3
mm.
Improvements are suggested and conclusions drawn regarding the design decisions considered critical to a
successful outcome for this type of procedure in the future
External cueing influences drop jump performance in trained young soccer players
Get PDFDrop jump (DJ) characteristics provide insight on power production and injury risk. The purpose of this study was to investigate the effect of external cueing on drop jump characteristics in young male soccer players. Fourteen academy soccer players performed DJs with four different conditions, control (CONT), contact cue (CC), height cue (HC), and quiet cue (QC). Performance measures were reactive strength index (RSI), jump height, ground contact time (GCT), and take-off impulse, with injury risk reflected by impact peak, impact timing and landing impulse. CC showed a very large significant reduction in GCT (ES > 2.0, p0.05) to CONT. The data showed that all cues provided a specific response; CC reduced GCT and increased RSI, HC increased jump height and QC reduced outcomes associated with injury risk. HC may be advantageous for young soccer players with a low training age as it shows a small to moderate increase in jump height without increasing injury risk. Young players may need to be safely progressed to be able to use a CC to facilitate high reactive strength without being exposed to undue injury risk
UBC-Nepal Expedition: Haemoconcentration underlies the reductions in cerebralblood flow observed during acclimatization to high-altitude
Get PDFAt high‐altitude, increases in haematocrit (Hct) are achieved through altitude‐induced diuresis and erythropoiesis, both of which result in increased arterial oxygen content (CaO2). Given the impact alterations in Hct have on CaO2, haemoconcentration has been hypothesized to partly mediate the attenuation of the initial elevation in cerebral blood flow (CBF) at high‐altitude. To test this hypothesis, healthy males (n = 13) ascended to 5050 m over nine days without the aid of prophylactic acclimatization medications. Following one‐week of acclimatization at 5050 m, participants were haemodiluted by rapid saline infusion (2.10 ± 0.28 L) to return Hct towards pre‐acclimatized levels. Arterial blood gases, Hct, global CBF (duplex ultrasound), and haemodynamic variables were measured following initial arrival to 5050 m, and after one‐week of acclimatization at high‐altitude, prior to and following the haemodilution protocol. Following one‐week at 5050 m, Hct increased from 42.5 ± 2.5 to 49.6 ± 2.5% (P < 0.001), and was subsequently reduced to 45.6 ± 2.3% (P < 0.001) following haemodilution. Global CBF decreased from 844 ± 160 to 619 ± 136 ml mi−1 n (P = 0.033) following one‐week of acclimatization and increased to 714 ± 204 ml mi−1n (P = 0.045) following haemodilution. Despite the significant changes in Hct, and thus CaO2, cerebral oxygen delivery was unchanged at all time points. Furthermore, these observations occurred in the absence of any changes in mean arterial blood pressure, cardiac output, arterial blood pH, or oxygen saturation pre‐ and post‐haemodilution. These data highlight the influence of Hct in the regulation of CBF and are the first to demonstrate experimentally that haemoconcentration contributes to the reduction in CBF during acclimatization to altitude
Spiritual moments making music in nature. A study exploring the experiences of children making music outdoors, surrounded by nature
Get PDFOutdoor learning is recognised internationally as an essential part of a child’s holistic education and children’s wellbeing can be improved when being outdoors surrounded by nature. However, there is a growing body of evidence that suggests children are becoming disconnected from nature. This study investigated the experiences of six classes of children aged 7–11 years from six primary schools making music outdoors in rural locations in Wales over a two-year period. Groups of children from each school undertook semi-structured interviews using video-stimulated reflective dialogue (VSRD). Their teachers also took part in semi-structured interviews, without VSRD. The data suggest children’s music making involved interactivity with nature provoking biophilic responses. The analysis revealed they experienced extraordinary, transcendent or what might be called spiritual moments. Evidence is analysed with conceptions of spirituality, communitas and philosophy of dialogue
Your Guess is as Good as Mine: Finding Your Way on Board a Cruise Ship
Get PDFWayfinding on board a large cruise ship might be mistakenly thought to be easy and straightforward, and this may well account for the absence of literature on this topic. This paper will address this gap by exploring and exposing the influences that shape our everyday practices while cruising, itself a moving experience, carrying us by consent across the seas to distant shores. The need to address on-site experiences is not as Pearce (2011) points out, always fully investigated in post-holiday satisfaction surveys, and so this exploration of how passengers react and respond to their cruise ship surroundings exposes the scale, and sometimes overwhelming enormity, of some of these vessels now selling a mass tourism product
Influence of resisted sled-push training on the sprint force-velocity profile of male high school athletes
No full textSled pushing is a commonly used form of resisted sprint training; however, little empirical evidence exists, especially in youth populations. The aim of this study was to assess the effectiveness of unresisted and resisted sled pushing across multiple loads. Fifty high school athletes were assigned to an unresisted (n = 12), or 3 resisted groups; light (n = 14), moderate (n = 13), and heavy (n = 11) resistance that caused a 25%, 50%, and 75% velocity decrement in maximum sprint speed, respectively. All participants performed two sled‐push training sessions twice weekly for 8 weeks. Before and after the training intervention, the participants performed a series of jump, strength, and sprint testing to assess athletic performance. Split times between 5 and 20 m improved significantly across all resisted groups (all P < .05, d = 0.34‐1.16) but did not improve significantly with unresisted sprinting. For all resisted groups, gains were greatest over the first 5 m (d = 0.67‐0.84) and then diminished over each subsequent 5 m split (d = 0.08‐0.57). The magnitude of gains in split times was greatest within the heavy group. Small but non‐significant within‐group effects were found in pre to post force‐velocity profiles. There was a main effect of time but no interaction effects as all groups increased force and power, although the greatest increases were observed with the heavy load (d = 0.50‐0.51). The results of this study suggest that resisted sled pushing with any load was superior to unresisted sprint training and that heavy loads may elicit the greatest gains in sprint performance over short distances
ICON 2019—International Scientific Tendinopathy Symposium Consensus: There are nine core health-related domains for tendinopathy (CORE DOMAINS): Delphi study of healthcare professionals and patients
Get PDFBackground: The absence of any agreed-upon tendon health-related domains hampers advances in clinical tendinopathy research. This void means that researchers report a very wide range of outcome measures inconsistently. As a result, substantial synthesis/meta-analysis of tendon research findings is almost futile despite researchers publishing busily. We aimed to determine options for, and then define, core health-related domains for tendinopathy.
Methods: We conducted a Delphi study of healthcare professionals (HCP) and patients in a three-stage process. In stage 1, we extracted candidate domains from clinical trial reports and developed an online survey. Survey items took the form: ‘The ‘candidate domain’ is important enough to be included as a core health-related domain of tendinopathy’; response options were: agree, disagree, or unsure. In stage 2, we administered the online survey and reported the findings. Stage 3 consisted of discussions of the findings of the survey at the ICON (International Scientific Tendinopathy Symposium Consensus) meeting. We set 70% participant agreement as the level required for a domain to be considered ‘core’; similarly, 70% agreement was required for a domain to be relegated to ‘not core’ (see Results next).
Results: Twenty-eight HCP (92% of whom had >10 years of tendinopathy experience, 71% consulted >10 cases per month) and 32 patients completed the online survey. Fifteen HCP and two patients attended the consensus meeting. Of an original set of 24 candidate domains, the ICON group deemed nine domains to be core. These were: (1) patient rating of condition, (2) participation in life activities (day to day, work, sport), (3) pain on activity/loading, (4) function, (5) psychological factors, (6) physical function capacity, (7) disability, (8) quality of life and (9) pain over a specified time. Two of these (2, 6) were an amalgamation of five candidate domains. We agreed that seven other candidate domains were not core domains: range of motion, pain on clinician applied test, clinical examination, palpation, drop out, sensory modality pain and pain without other specification. We were undecided on the other five candidate domains of physical activity, structure, medication use, adverse effects and economic impact.
Conclusion: Nine core domains for tendon research should guide reporting of outcomes in clinical trials. Further research should determine the best outcome measures for each specific tendinopathy (ie, core outcome sets)
Trajectory of auditory and language development in the early stages of pre-lingual children post cochlear implantation: A longitudinal follow up study
Get PDFObjectives
The aim of this longitudinal follow-up study was to explore the trajectories of early auditory and language development in Mandarin speaking children younger than 3 years of age following switch-on of their cochlear implants (CIs).
Methods
Early auditory and language development was measured longitudinally using the Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS), which is a commonly used tool for assessing early prelingual auditory development (EPLAD) in children, and the subtest (Words and Gestures, W&G) of the simplified short form version of the Mandarin Communicative Development Inventory (SSF-MCDI) to assess receptive and expressive vocabulary growths of children in 24 pediatric cochlea implant recipients at baseline, 3, 6, and 12 months following switch-on. Age at switch-on ranged from 1 to 3 years of age. Participants were divided into two groups based on age at switch-on. The IT-MAIS and SSF-MCDI (W&G) scores were analyzed with comparison to normal children, unaided hearing-impaired children, and CI children.
Results
Significant improvements in IT-MAIS and SSF-MCDI (W&G) scores from baseline to 12 months were seen after switch-on in both CI groups and were comparable to the normal hearing children in the first year of age. The IT-MAIS scores of CI children in both groups at 12 months after switch-on surpassed the average level of unaided peers with profound hearing loss and were similar to the average level of unaided peers with mild hearing loss. SSF-MCDI (W&G) scores in word comprehension and expression were significantly different between groups at some intervals.
Conclusions
Children younger than 3 years of age with cochlear implants have similar trajectories in early auditory and language developments to normally hearing children. Moreover, early implantation is an important factor for the early auditory development when comparing EPLAD results between CI children and unaided peers with different hearing loss. Finally, it is noteworthy that CI children master the skill of word comprehension before the skill of word expression, and that word comprehension may be the basis of word expression
Should responsible management education become a priority? A qualitative study of academics in Egyptian public business schools
Get PDFIn this paper we investigate why responsible management education (RME) should become a necessity in Egyptian public business schools. A total of 80 academics from three universities were contacted and interviewed in six different focus groups. Three types of motives were identified from the interviews: extrinsic local, intrinsic school and extrinsic global, which inspired academics to believe in the importance of implementing RME in their business schools. Most respondents consider implementing RME is crucial to rebuilding their schools' legitimate and ethical role. Focusing only on academics rather than the executives of the selected business schools, is perceived to be a limitation. Moreover, addressing only public business schools and excluding private ones may limit the authors’ ability to generalize results. Thus, the authors of this paper invite researchers from the fields of cultural diversity, CSR, sustainability and higher education (HE) to collaborate in producing more interdisciplinary and/or trans-disciplinary papers on the same topic. Future researchers may seek to investigate the perceptions of management in the addressed business schools. Replicating this study with private business schools in Egypt may be considered another research opportunity. The educational authorities need to develop a framework for implementing and assessing RME in public business schools. This paper contributes by filling a gap in HE management, responsible leadership, and sustainability literature in which empirical studies on RME and the responsible practices of academics have been limited so far