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Self - Propelled Robotic System with a Visco - Elastic Joint: Dynamics and Motion Analysis
Get PDFThis paper studies the dynamics and motion generation of a self
-
propelled robotic
system with a visco
-
elastic joint. The system is underactuated,
legless and wheelless, and has
potential applications in environmental inspection and operation in restricted space which are
inaccessible to human beings, such as pipeline inspection, medical assistance and disaster
rescues. Locomotion of the system relie
s on the stick
-
slip effects, which interacts with the
frictional force at the surface in contact. The nonlinear robotic model utilizes combined
tangential
-
wise and normal
-
wise vibrations for underactuated locomotion, which features a
generic significance f
or the studies on self
-
propelled systems. To identify the characteristics
of the visco
-
elastic joint and shed light on the energy efficacy, parameter dependences on
stiffness and damping coefficients are thoroughly analysed. Our studies demonstrate that
dy
namic behaviour of the self
-
propelled system is mainly periodic and desirable forward
motion is achieved via identification of the variation laws of the control parameters and
elaborate selection of the stiffness and damping coefficients. A motion generati
on strategy is
developed, and an analytical two
-
stage motion profile is proposed based on the system
response and dynamic constraint analysis, followed by a parameterization procedure to
optimally generate the trajectory. The proposed method provides a nov
el approach in
generating self
-
propelled locomotion, and designing and computing the visco
-
elastic
parameters for energy efficacy. Simulation results are presented to demonstrate the
effectiveness and feasibility of the proposed model and motion generation
approach
Judging athletes’ moral actions: some critical reflections
Get PDFApproving or disapproving of athletes’ moral conduct and character is commonplace. In this essay I explore to what extent such judgements are valid and reliable moral judgements. I identify some methodological problems associated with making moral judgements particularly, but not exclusively, from a virtue perspective. I argue that we have no reliable access to states of mind needed to make informed evaluations. Moreover, even if such access was available, the validity of our judgements would be compromised or limited by our own moral character
Cardiac structure and function characterized across age groups and between sexes in healthy wild-born captive chimpanzees (Pan troglodytes) living in sanctuaries
No full textObjective: To comprehensively characterize cardiac structure and function, from infancy to adulthood, in male and female wild-born captive chimpanzees (Pan troglodytes) living in sanctuaries. Animals: 290 wild-born captive chimpanzees. Procedures: Physical and echocardiographic examinations were performed on anesthetized chimpanzees in 3 sanctuaries in Africa between October 2013 and May 2017. Results were evaluated across age groups and between sexes, and potential differences were assessed with multiple 1-way independent Kruskal-Wallis tests. Results: Results indicated that left ventricular diastolic and systolic function declined at a younger age in males than in females. Although differences in right ventricular diastolic function were not identified among age groups, right ventricular systolic function was lower in adult chimpanzees (> 12 years old), compared with subadult (8 to 12 years old) and juvenile (5 to 7 years old) chimpanzees. In addition, male subadult and adult chimpanzees had larger cardiac wall dimensions and chamber volumes than did their female counterparts. Conclusions and Clinical Relevance: Results of the present study provided useful reference intervals for cardiac structure and function in captive chimpanzees categorized on the basis of age and sex; however, further research is warranted to examine isolated and combined impacts of blood pressure, age, body weight, and anaesthetic agents on cardiac structure and function in chimpanzees
Feasibility study to determine the external validity of the Diabetic Foot Screening Tool in detecting risk factors in the end stage renal disease population on haemodialysis therapy
No full textOver the past three decades there has been a dramatic increase in the prevalence of End Stage Renal Disease (ESRD) which has heightened the global demand for renal replacement therapy. This is of particular importance because dialysis therapy is associated with high economic costs, a reduced quality of life and premature mortality relating from a wide range of metabolic complications.1One of the main challenges facing the Chronic Kidney Disease (CKD) population in Wales is that it currently has the highest incidence of haemodialysis therapy in the United Kingdom (UK). The impact of this is further compounded given that a high proportion of this population has diabetic nephropathy (28.2%) documented as their primary diagnosis.2 This may be attributed to the fact that social deprivation figures in Wales (48%) are substantially higher than in England (38%). It is estimated that people living in the most deprived areas in the UK are 2.5 times more likely to develop Type II diabetes as a consequence of poor nutritional choices and a sedentary lifestyle
Art, philosophy and the connectivity of concepts
Get PDFIn the history of philosophy, concepts are traditionally pictured as discrete containers that bring together objects or qualities based on the possession of shared, uniform properties. This paper focuses on a contrasting notion of the concept which holds that concepts are defined by their capacity to reach out and connect with other concepts. Two theories in recent continental philosophy maintain this view: one from Ricoeur, the other from Deleuze and Guattari. Both are offered as attempts to bring art and philosophy into relation, but they differ over how the process of connection is theorized. With Ricoeur, a concept is only a concept if it is inherently predisposed to connect with others, and open to being misapplied through metaphor, whereas, with Deleuze and Guattari, connection is left as the general notion of each and every concept being mutually consistent with other concepts, with the consistency attributed to the external action of “bridging”. I demonstrate the impact of this difference on how the philosophers perceive the art–philosophy relation, and argue that Ricoeur is better placed to provide a theory of philosophical discourse that is open to the aesthetic. Ricoeur can show it through metaphor, while Deleuze and Guattari can only assert or state an art–philosophy relation through a series of technical claims. The significance of the showing–saying distinction is that it can demonstrate the depth with which conceptual connectivity is located with the philosophers’ respective ontologies and, within this, it can help to reveal the value of conceptual connectivity for that ontology
Transformational leadership, organizational justice and organizational outcomes
Get PDFPurpose:
The purpose of this paper is to examine the impact of transformational leadership (TL) on organizational commitment (OC) with the mediating role of organizational justice (OJ) in the higher education (HE) sector in Syria.
Design/methodology/approach:
The data were collected from 502 employees from six HE institutions. Two measures of organizational outcomes were selected for this study, namely, job satisfaction (JS) and OC. Using structural equation modelling (SEM), the authors tested four alternative models to indicate the relationship between leadership and organizational outcomes.
Findings:
TL has both direct and indirect effects on OC through interactional justice (IJ). TL has an impact on JS through procedural justice (PJ) and IJ as intermediate variables, while transactional leadership (TrL) has an impact on JS through distributive justice (DJ). The three types of OJ have an impact on OC through JS. The authors found that the national culture may not influence the impact of the leader in the current globalization context, as the results were similar to the Western studies.
Practical implications:
The findings of the study provide managers of the HE sector with insights into the formations of employees’ fairness perceptions, and with some guidelines for managing employees by documenting OJ to draw positive attitudinal and behavioral responses from employees.
Originality/value:
While most previous research has focused on exploring the relationship between leadership and OJ or between OJ and JS in the business sector, the study, however, seeks in addition, to pinpoint the effect of OJ as a mediate variable between the leadership and JS and OC in HE
Co-design, evaluation and the Northern Ireland Innovation Lab
Get PDFAround the world there are more than 100 policy labs—multi-disciplinary government teams developing public services and policies using innovation methods to engage citizens and stakeholders. These policy labs use a range of innovation methods and approaches, including co-production, co-creation, co-design, behavioural insights, systems thinking, ethnography, data science, nudge theory and lean processes. Although the methods may vary, one element is consistent: policy labs actively, creatively and collaboratively engage the public and a wide range of stakeholders in jointly developing solutions. The Northern Ireland Public Sector Innovation Lab (iLab) is part of a growing UK and international community of policy labs using co-design to engage with users for value co-creation, aiming to improve public governance by creating a safe space to generate ideas, test prototypes and refine concepts with beneficiaries. Drawing on iLab’s experience, this paper explores three questions: What are the main determinants of effective co-design? What are the unintended consequences of co-design? And what lessons can be learned from iLab and shared with other policy labs
First-stance phase force contributions to acceleration sprint performance in semi-professional soccer players
Get PDFBackground: Sprint running is a key determinant of player performance in soccer that is typically assessed and monitored using temporal methods. Purpose: The aim of this study was to examine the relationship between ground reaction force kinetics at the first step and sprint running performance in soccer players in order to enhance the development of training and assessment methods. Methods: Nineteen semi-professional soccer players participated (mean ± s: age 21.1 ± 1.9 years, body mass 79.4 ± 7.3 kg and stature 1.79 ± 0.06 m). The participants completed 20 m acceleration sprint runs as timing gates recorded split times between 0–5, 5–10, 10–15, 15–20 and 0–20 m. A force plate captured vertical, anteroposterior and mediolateral ground reaction force data (1000 Hz) of the first right foot strike stance phase. Results: Ground reaction force metrics, including peak anteroposterior propulsive force (r = 0.66 to 0.751; P = .000 to .002), peak vertical ground reaction force (r = 0.456 to 0.464; P = .045 to .05), average medial-lateral/anteroposterior orientation angle (r = −0.463; P = .023), and average anteroposterior/vertical orientation angle (r = −0.44; P = .03) were correlated with one or all split times between 0–5 m, 5–10 m, 10–15 m, 15–20 m and 0–20 m. Conclusions: Acceleration sprint running in soccer requires minimised mediolateral and increased anteroposterior loading in the stance phase. Multi-component ground reaction force measures of the first step in acceleration sprint runs are important for developing performance assessments, and understanding force application techniques employed by soccer players
The overlooked significance of plasma volume for successful adaptation to high altitude in Sherpa and Andean natives
Get PDFIn contrast to Andean natives, high altitude Tibetans present with a lower hemoglobin concentration that correlates with reproductive success and exercise capacity. Decades of physiological and genomic research have assumed that the lower hemoglobin concentration in Himalayan natives results from a blunted erythropoietic response to hypoxia (i.e. no increase in total hemoglobin mass). In contrast, herein we test the hypothesis that the lower hemoglobin concentration is the result of greater plasma volume, rather than an absence of increased hemoglobin production. We assessed hemoglobin mass, plasma volume and blood volume in lowlanders at sea level, lowlanders acclimatized to high altitude, Himalayan Sherpa and Andean Quechua, and explored the functional relevance of volumetric hematological measures to exercise capacity. Hemoglobin mass was highest in Andeans, but also elevated in Sherpa compared to lowlanders. Sherpa demonstrated a larger plasma volume than Andeans, resulting in a comparable total blood volume at a lower hemoglobin concentration. Hemoglobin mass was positively related to exercise capacity in lowlanders at sea level and Sherpa at high altitude, but not in Andean natives. Collectively, our findings demonstrate a unique adaptation in Sherpa that reorientates attention away from hemoglobin concentration and towards a paradigm where hemoglobin mass and plasma volume may represent phenotypes with adaptive significance at high altitude
The Effect of Mechanical Overloading on Surface Roughness of the Coronary Arteries
Get PDFBackground. Surface roughness can be used to identify disease within biological tissues. Quantifying surface roughness in the coronary arteries aids in developing treatments for coronary heart disease. This study investigates the effect of extreme physiological loading on surface roughness, for example, due to a rupture of an artery. Methods. The porcine left anterior descending (LAD) coronary arteries were dissected ex vivo. Mechanical overloading was applied to the arteries in the longitudinal direction to simulate extreme physiological loading. Surface roughness was calculated from three-dimensional reconstructed images. Surface roughness was measured before and after damage and after chemical processing to dehydrate tissue specimens. Results. Control specimens confirmed that dehydration alone results in an increase of surface roughness in the circumferential direction only. No variation was noted between the hydrated healthy and damaged specimens, in both the longitudinal ( and ) and circumferential ( and ) directions. After dehydration, an increase in surface roughness was noted for damaged specimens in both the longitudinal () and circumferential () directions. Conclusions. Mechanical overloading applied in the longitudinal direction did not significantly affect surface roughness. However, when combined with chemical processing, a significant increase in surface roughness was noted in both the circumferential and longitudinal directions. Mechanical overloading causes damage to the internal constituents of the arteries, which is significantly noticeable after dehydration of tissue