Effective Viscous Damping Enables Morphological Computation in Legged Locomotion

Muscle models and animal observations suggest that physical damping is beneficial for stabilization. Still, only a few implementations of mechanical damping exist in compliant robotic legged locomotion. It remains unclear how physical damping can be exploited for locomotion tasks, while its advantages as sensor-free, adaptive force- and negative work-producing actuators are promising. In a simplified numerical leg model, we studied the energy dissipation from viscous and Coulomb damping during vertical drops with ground-level perturbations. A parallel spring-damper is engaged between touch-down and mid-stance, and its damper auto-disengages during mid-stance and takeoff. Our simulations indicate that an adjustable and viscous damper is desired. In hardware we explored effective viscous damping and adjustability and quantified the dissipated energy. We tested two mechanical, leg-mounted damping mechanisms; a commercial hydraulic damper, and a custom-made pneumatic damper. The pneumatic damper exploits a rolling diaphragm with an adjustable orifice, minimizing Coulomb damping effects while permitting adjustable resistance. Experimental results show that the leg-mounted, hydraulic damper exhibits the most effective viscous damping. Adjusting the orifice setting did not result in substantial changes of dissipated energy per drop, unlike adjusting damping parameters in the numerical model. Consequently, we also emphasize the importance of characterizing physical dampers during real legged impacts to evaluate their effectiveness for compliant legged locomotion

Psychological morbidity and job satisfaction among teachers in private secondary schools

Background: Teachers are an inseparable corner stone of the society and their satisfaction will affect the quality of service they render. Poor job satisfaction could result in job stress and this could affect their psychological health. This study aims to ascertain the level, causes of job dissatisfaction, intentions to quit and psychological morbidity among teachers in private secondary schools in a developing country.Methods: A cross-sectional study was conducted among teachers (392) in private secondary schools in Benin-City, Edo-State Nigeria, between June 2003 to November 2003. A total population of 400 teachers who had spent at least one year in the service were included in the study. The respondents completed a self – administered designed questionnaire and a standard instrument – The General Health Questionnaire (GHQ 28)Results: The response rate was 98%. Fifty- eight (14.8%) of the respondents had psychological morbidity (GHQ score of 4 and above). One hundred and seventy - eight (45.4%) teachers were very satisfied or satisfied with their jobs. A significant number (45.9%) of teachers would want to quit their jobs. The proportion of teachers with GHQ score 4 and above increased with the level of dissatisfaction but this was not found to be statistically significant. Poor salary was found to be the main cause of job dissatisfaction and major reason for wanting to quit the job.Conclusion: This study shows a low level of job satisfaction among Nigerian teachers. Poor salary was the major cause of job dissatisfaction and intension to quit. Further work need to be done to ascertainthe association of psychological morbidity and job dissatisfaction

Fast Sensing and Adaptive Actuation for Robust Legged Locomotion

Robust legged locomotion in complex terrain demands fast perturbation detection and reaction. In animals, due to the neural transmission delays, the high-level control loop involving the brain is absent from mitigating the initial disturbance. Instead, the low-level compliant behavior embedded in mechanics and the mid-level controllers in the spinal cord are believed to provide quick response during fast locomotion. Still, it remains unclear how these low- and mid-level components facilitate robust locomotion. This thesis aims to identify and characterize the underlining elements responsible for fast sensing and actuation. To test individual elements and their interplay, several robotic systems were implemented. The implementations include active and passive mechanisms as a combination of elasticities and dampers in multi-segment robot legs, central pattern generators inspired by intraspinal controllers, and a synthetic robotic version of an intraspinal sensor. The first contribution establishes the notion of effective damping. Effective damping is defined as the total energy dissipation during one step, which allows quantifying how much ground perturbation is mitigated. Using this framework, the optimal damper is identified as viscous and tunable. This study paves the way for integrating effective dampers to legged designs for robust locomotion. The second contribution introduces a novel series elastic actuation system. The proposed system tackles the issue of power transmission over multiple joints, while featuring intrinsic series elasticity. The design is tested on a hopper with two more elastic elements, demonstrating energy recuperation and enhanced dynamic performance. The third contribution proposes a novel tunable damper and reveals its influence on legged hopping. A bio-inspired slack tendon mechanism is implemented in parallel with a spring. The tunable damping is rigorously quantified on a central-pattern-generator-driven hopping robot, which reveals the trade-off between locomotion robustness and efficiency. The last contribution explores the intraspinal sensing hypothesis of birds. We speculate that the observed intraspinal structure functions as an accelerometer. This accelerometer could provide fast state feedback directly to the adjacent central pattern generator circuits, contributing to birds’ running robustness. A biophysical simulation framework is established, which provides new perspectives on the sensing mechanics of the system, including the influence of morphologies and material properties. Giving an overview of the hierarchical control architecture, this thesis investigates the fast sensing and actuation mechanisms in several control layers, including the low-level mechanical response and the mid-level intraspinal controllers. The contributions of this work provide new insight into animal loco-motion robustness and lays the foundation for future legged robot design

The Determinants of Dividend Payments in UK: An Empirical Analysis

Abstract This dissertation is to investigate the determinants of dividend payments in UK. In this study, 50 firms listed in UKfrom five industries are selected to use as sample dataset between 2005 and 2011. Six determinants (profitability, firm size, liquidity, investment opportunity, and leverage and asset structure) are chose based on the previous studies and theories. Moreover, six hypotheses of these determinants have been established and tested by using regression model. Empirical findings concluded that the profitability, firm size, leverage and asset structure are strongly and significantly positive to dividend payments. Investment opportunity is the only one determinant that has an inverse correlation with dividend payments. In addition, there is no association between liquidity and dividend distribution. These results indicated some important issues. Firstly, firms‟ dividend payment was proved that they highly depend on their profitability. Secondly, firms prefer to pay higher dividends to mitigate the agency problems. Thirdly, investment opportunity has negative effect on dividend payment. But, this conclusion cannot represent that firms cut dividends to support their investments. The positive relationship between leverage and dividend distribution can explain that firms borrow more debts to pay dividends and finance their investment. Thus, they can use higher dividend payments to convey information to the outsiders

The Effect of Kinesio Tape® on Lower Extremity Functional Movement Screen™ Scores

International Journal of Exercise Science 5(3) : 196-204, 2012. The purpose was to determine if application of Kinesio Tape (KT®) improves lower extremity scores on the Functional Movement Screen (FMS™). Individual FMS™ score assessments of 32 college students were obtained. The subjects were then randomized into treatment and control groups. The treatment group had a second FMS™ score after application of KT® to the lower extremity while the control group had a second FMS™ score with no intervention. 16 varsity women’s basketball players and 16 non-varsity female students (Tegner Scale: 6.84 ±1.25, Age: 19±1.2, Height: 165.1±15.1cm, Weight: 68.1±10.9kg) at a NCAA Division II institution participated. FMS™ scores were collected and recorded by the principal investigator. Data was analyzed through two way analysis of variance (ANOVA). Post hoc analysis indicated the treatment group significantly improved in comparison to the control group (Left: P\u3c.001, 95% CI: .283 - .467; Right P\u3c.001, 95% CI: .327 - .523) for both sides of the Hurdle Step. There were no interactions with Deep Squat (P=0.667) or either side of In-Line Lunge (Left: P=0.291, and Right: P=0.530). There were no interactions with either group in Deep Squat and In-Line Lunge of FMS™. However, there was a significant interaction with both groups in the Hurdle Step of FMS™. Findings from this research suggest that KT® may improve movement that incorporates a non-weight-bearing segment

XXII International Conference on Chemical Reactors - Editorial

The XXII International Conference on Chemical Reactors, CHEMREACTOR-22, was organized by the Boreskov Institute of Catalysis of the Siberian Branch of the Academy of Sciences, Novosibirsk, Russia, together with University College London (UCL), UK. The conference took place during 19-23 September 2016 in London, and was held under the auspices of the European Federation of the Chemical Engineering (EFCE). The conference brought together about 200 researchers and engineers from 30 countries all over the world. As in previous editions of CHEMREACTOR, the conference was devoted to fundamental aspects and practical application of catalytic processes and chemical reactors, as well as to the development of novel technologies in this area. The scientific program of the conference included 6 plenary lectures, 9 keynote lectures, 68 oral and 100 poster presentations on the following topics

Multi-segmented Adaptive Feet for Versatile Legged Locomotion in Natural Terrain

Most legged robots are built with leg structures from serially mounted links and actuators and are controlled through complex controllers and sensor feedback. In comparison, animals developed multi-segment legs, mechanical coupling between joints, and multi-segmented feet. They run agile over all terrains, arguably with simpler locomotion control. Here we focus on developing foot mechanisms that resist slipping and sinking also in natural terrain. We present first results of multi-segment feet mounted to a bird-inspired robot leg with multi-joint mechanical tendon coupling. Our one- and two-segment, mechanically adaptive feet show increased viable horizontal forces on multiple soft and hard substrates before starting to slip. We also observe that segmented feet reduce sinking on soft substrates compared to ball-feet and cylinder-feet. We report how multi-segmented feet provide a large range of viable centre of pressure points well suited for bipedal robots, but also for quadruped robots on slopes and natural terrain. Our results also offer a functional understanding of segmented feet in animals like ratite birds