Matrix Transfer Function Design for Flexible Structures: An Application

The application of matrix transfer function design techniques to the problem of disturbance rejection on a flexible space structure is demonstrated. The design approach is based on parameterizing a class of stabilizing compensators for the plant and formulating the design specifications as a constrained minimization problem in terms of these parameters. The solution yields a matrix transfer function representation of the compensator. A state space realization of the compensator is constructed to investigate performance and stability on the nominal and perturbed models. The application is made to the ACOSSA (Active Control of Space Structures) optical structure

Interval-Valued Kriging Models with Applications in Design Ground Snow Load Prediction

One critical consideration in the design of buildings constructed in the western United States is the weight of settled snow on the roof of the structure. Engineers are tasked with selecting a design snow load that ensures that the building is safe and reliable, without making the construction overly expensive. Western states use historical snow records at weather stations scattered throughout the region to estimate appropriate design snow loads. Various mapping techniques are then used to predict design snow loads between the weather stations. Each state uses different mapping techniques to create their snow load requirements, yet these different techniques have never been compared. In addition, none of the current mapping techniques can account for the uncertainty in the design snow load estimates. We address both issues by formally comparing the existing mapping techniques, as well as creating a new mapping technique that allows the estimated design snow loads to be represented as an interval of values, rather than a single value. In the process, we have improved upon existing methods for creating design snow load requirements and have produced a new tool capable of handling uncertain climate data

MUSCLE SYNERGY DURING A SINGLE LEG STANDING TEST IN AMBULATORY CHILDREN WITH CEREBRAL PALSY

INTRODUCTION: Cerebral Palsy (CP) is a sensorimotor disorder characterized by dysfunctional motor coordination, balance problems, and loss of selective motor control. Motor coordination exhibited as co-contraction, has been subjectively quantified using gait analysis, but recent studies have begun to objectively analyze the amount of co-contraction by collecting electromyography (EMG) data. Center of pressure excursion (COPE) measurements collected during a single leg standing test (SLST) have shown to be more valid measurements of balance in populations with motor disabilities than a SLST alone. A recent study has correlated increased COPE velocity with a lower fall risk as determined by reported fall frequency, suggesting a more objective measure of fall risk. The current study aimed to determine if the fall risk calculated by COPE velocity in children with CP is correlated with co-contraction index value in various muscle synergy groups. It was hypothesized that i) co-contraction index values will differ between high and low fall risk groups, ii) there will be preferential activation of different synergy groups within the high and low fall risk groups, and iii) there will be a negative and direct correlation between COPE velocity and co-contraction index values for all synergy groups. METHODS: Fall risk grouping was determined by average COPE velocity values calculated from previously reported fall frequency groups. Balance ability was determined by COPE measurements during a SLST on a force plate. Muscle synergy groups were determined by common muscle pairings at the hip, knee and ankle. Co-contraction indices were determined from linear envelopes plotted from muscle group EMG data. An independent t-test was run on muscle synergy groups between high and low fall risk groups. Nonparametric Analysis of Variance (ANOVA) and Tukey post-hoc tests were run on the high and low fall risk groups separately to determine differences in co-contraction index value within high and low fall risk groups. A Pearson correlation analyzed COPE velocity and co-contraction index value. RESULTS: No significant differences in muscle synergy between the high and low fall risk groups were found (p = 0.476, 0.076, 0.064, 0.364). The ANOVA and Tukey post-hoc tests for high fall risk group found significant differences in co-activation index value between the sagittal hip and frontal hip groups (p = 0.022) and sagittal hip and ankle groups (p = 0.016). Low fall risk group was found to have significant differences between the sagittal hip and frontal hip groups (p = 0.038) and frontal hip and knee groups (p = 0.012). Weak and negative correlations were found between COPE velocity and both knee and ankle groups (r = -0.309, -0.323, p = 0.059, 0.050). Negligible and insignificant correlations were found between frontal hip and sagittal hip synergies and COPE velocity ((r = 0.013, -0.068, p = 0.475, 0.367). CONCLUSION: There is insufficient evidence to claim that muscle group activations are different depending on fall risk grouped by COPE velocity. It is not currently possible to correlate COPE velocity to a specific synergy group recruitment. However, data do suggest that sagittal hip and knee strategies are recruited more than ankle and frontal hip strategies during SLST

Development of Prediction Models to Estimate 1-RM for Upper and Lower Body Exercises in Non-Resistance Trained Women

PURPOSE: The purpose of this investigation was to develop and validate a one-repetition maximum (1-RM) prediction model for the upper and the lower body in non-resistance trained women. METHODS: Sixty seven healthy, non-resistance trained women between the ages of 18 and 25 years volunteered for this investigation. The investigation was performed in 2 phases. During phase I, all subjects completed 2 experimental sessions. During the first session, subjects performed a bench press repetition to fatigue (RTF) test with 45 lb and 55 lb. Subjects also performed a leg press RTF with 175 lb and 215 lb. Additional variables that were measured were: body height (in.), body weight (lb), and sum of skinfolds (mm). During the second session, subjects performed a 1-RM bench press and a 1-RM leg press. Phase II of the experiment involved the development and validation of 1-RM prediction models for the bench press and the leg press exercise. RESULTS: A stepwise regression analysis was carried out to develop a 1-RM prediction model for the bench press exercise and for the leg press exercise. The initial set of predictor variables considered for the upper body prediction model were: RTF with the bench press, body height (in.), body weight (lb), and sum of skinfolds (mm). The variable selected by the stepwise regression analysis for inclusion in the bench press prediction model was RTF with 55 lb (r = 0.914). The model to predict 1-RM bench press was: Model I: 1-RM bench press = 56.199 + 1.94(RTF55). A paired samples t-test indicated that the difference between the mean measured and mean predicted 1-RM was not significant (p>.05). The correlation between the measured and the predicted 1-RM values for the bench press was r = 0.935. The initial set of predictor variables considered for the lower body prediction model were: RTF with the leg press, body height (in.), body weight (lb), and sum of skinfolds (mm). The variables selected by the stepwise regression analysis for inclusion in the leg press prediction model were RTF with 215 lb and body weight (lb) (r = 0.798). The model to predict 1-RM leg press was: Model II: 1-RM leg press = 145.099 + 2.752 (RTF215) + .618 (body weight). A paired samples t-test indicated that the difference between the mean measured and mean predicted 1-RM was not significant (p>.05). The correlation between the measured and the predicted 1-RM values for the leg press was r = 0.695. CONCLUSION: The models developed in this investigation can be used to estimate the upper and/or lower body 1-RM strength of non-resistance trained women. These models will be useful for coaches, personal trainers, and fitness professionals who wish to design strength-training programs to enhance performance and the health-fitness levels of recreationally active females

The Robes of the Medical Royal Colleges and Other Societies: Medical Education ouside the Universities

In his book English University Life in the Middle Ages Alan Cobban remarked on the theoretical nature of medical education in the Middle Ages. Many men who graduated were more interested in teaching the subject than in the practice of medicine. A more practical approach would be gained from Continental centres, Padua and Leiden, but the non-academic bodies in London, the two Royal Colleges and the Society of Apothecaries would play an important part. The author assesses and analyzes how the formation of the profession would influence the development of ceremonial robes outside the two ancient universities. [Excerpts]

Ground and excited state electron transfer dynamics

The focus of this work is the investigation of the factors controlling electron transfer in molecular electronic systems, in particular those affecting electron transfer to and from electronically excited states. To achieve this, a number of mono- and trimetallic osmium and ruthenium complexes were synthesised and characterised. Monolayers of an osmium polypyridyl complex bound to a platinum microelectrode via a ¿rara-l,2-bis-(4-pyridyl)ethylene bridge were formed to probe ground state electron transfer dynamics. This is compared to the rate of photoinduced oxidative electron transfer quenching which occurs in a trimetallic osmium complex where the metal centres are linked by the same bridging ligand. The rate constant for this quenching is 1.3 xlO8 s '1, compared to 2 x 106 s '1 for the ground state process with the same driving force. These investigations show that the strength of coupling across the bpe ligand is higher when it links two metal centres as opposed to when it bridges a metal centre and an electrode. Extensive experiments were carried out to quantify the effect of laser pulses on an unmodified electrode surface. Laser activation improves the heterogeneous kinetics of a solution phase redox probe by removing polishing debris and other adsorbed impurities. Laser-induced current transients observed following a single laser pulse are due to a rapid (jas) restructuring of the double-layer followed by a slow (ms) thermal decay within the metal electrode. A mathematical model has yielded values of the thermal diffusion coefficient as a function of applied potential. To investigate excited state heterogeneous electron transfer, monolayers of a ruthenium polypyridyl complex containing the bridging ligand, 2,2':4,4":4',4"- Quarterpyridyl are used. Using Rehm-Weller calculations, the excited state redox potentials occur a t -0.71 and +1.05 V for oxidation and reduction respectively. Laser excitation of these monolayers in conjunction with high-speed cyclic voltammetry was utilised to attempt to directly measure the excited state redox potentials of this complex. This experiment has not been entirely successful and suggestions for improvements to the experiment are discussed

Implementation of Static RFID Landmarks in SLAM for Planogram Compliance

Autonomous robotic systems are becoming increasingly prevalent in everyday life and exhibit robust solutions in a wide range of applications. They face many obstacles with the foremost of which being SLAM, or Simultaneous Localization and Mapping, that encompasses both creation of the map of an unknown environment and localization of the robot in said environment. In this experiment, researchers propose the use of RFID tags in a semi-dynamic commercial environment to provide concrete landmarks for localization and mapping in pursuit of increased locational certainty. With this obtained, the ultimate goal of the research is to construct a robotics platform for planogram compliance and inventory management to provide consistency between online retail platforms and brick and mortar stores. The platform of choice is the Turtlebot3 Burger platform, by ROBOTIS, modified to hold an RFID reader. With existing packages, researchers are provided with the ability to essentially perform SLAM on a base level using an inbuilt Lidar sensor. It is from these existing packages that researchers plan to build a system to localize RFID tags in generated maps to provide a quantifiable decrease in localization time and increase in certainty

Modelling of DPF regeneration using microwave energy

FEM based models in COMSOL multiphysics have been used to simulate regeneration of diesel particulate filter following the layout of an existing microwave cavity. The study utilized the physics packages in the software to model the electric field and thermal profiles of the microwave cavity and DPF. This was used to establish dimensions for microwave cavity and DPF. Further it was possible to integrate the heating properties of the Silicon Carbide used in the DPF substrate. The electric field and thermal profiles of the microwave cavity, as well as the DPF were investigated for the established dimensions and simulated results were compared with experiments. In the experiment, we deployed microwave power generated by a 2.45GHz magnetron into the existing microwave cavity to regenerate DPF. The results of the experiments showed the thermal profiles during DPF regeneration to be in agreement with the profiles from the simulated results. The scheme was further used to improve the design of the cavity for better energy utilization and DPF regeneration efficiency. Electric field and thermal profiles of the microwave cavity were established for various dimensions of microwave cavity for a given DPF size and the results were investigated. It was found that cylindrical cavity (diameter of 153mm and length of 533mm) gives the optimal dimensions for the regeneration of a commercial DPF (143mm (diameter) x 183mm (length) viewed in terms of near homogeneous electric field distribution.Authors wish to acknowledge InnovateUK for the financial support provided to the project ‘Marine Exhaust Gase Treatment System (MAGS) {grant reference number 42471-295209)’, in which, the presented work is part of