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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

Analysis of Davit Structure with a Telescopic Arm of a Ship

Chen, Hong-long 20 July 2007 (has links)
Abstract Maritime transportation is important to national development because of Taiwan is in surrounding seas region. Therefore it is necessary that this research aimed to safety of the crane transportation system. This research investigated davit structure with a telescopic arm of a ship by means of the static analysis and modal analysis. To achieve the purpose, the researcher used the computer-aided design software Solidworks to set up this structure model. After that, he used finite element analysis software ANSYS to analyze the data. This research simulated in three situations. In static analysis, the researcher found the maximum displacement, the maximum von Mises stress and factors for safety of the structure in 16 dimensional sets in 53¢X of inclination at the davit with the telescopic arm being the shortest. After that, he discussed its tendency situation. In addition, he also checked the original structure in 53¢X of inclination at the davit with the telescopic arm being the longest and horizontal at the davit with the telescopic arm being the longest, respectively. In modal analysis, the researcher found natural frequencies and vibration shapes of the original structure. The structure had good vibration-proof ability and the resonance effect possibility not to be high. Generally, the researcher hoped that this study could provide helpful references for the relevant davit structure designers in the future.
162

PATHOPHYSIOLOGY AND CLINICAL PICTURE OF HAND-ARM VIBRATION SYNDROME IN JAPANESE WORKERS

MATOBA, TSUNETAKA 05 1900 (has links)
No description available.
163

CLINICAL ASSESSMENT OF HAND-ARM VIBRATION SYNDROME

KUSIAK, ROBERT, PELMEAR, PETER L. 05 1900 (has links)
No description available.
164

HAND-ARM VIBRATION EXPOSURE AND THE DEVELOPMENT OF VFFIRATION SYNDROME

IWATA, HIROTOSHI, TAKEDA, SHINTARO, KURODA, MOTOTSUGU, MIYAMOTO, KUNIHIKO, MIYASHITA, KAZUHISA 05 1900 (has links)
No description available.
165

Vibrationsbaserad maskinaktivitetssensor / Vibration based machine activity sensor

Bergquist, Albert January 2006 (has links)
<p>I detta projekt undersöker vi om man kan bygga en maskinaktivitetssensor med</p><p>hjälp av en enkretsdator som genom en accelerometer mäter en maskins</p><p>vibrationer. Sensorn skall generera en statussignal. Accelerometern ger en</p><p>mätbar signal baserad på maskinens vibrationer. Enkretsdatorn används för att</p><p>sampla, transformera och analysera signalen och generera statusinformation.</p><p>Med LabView kan vi spara, studera och analysera olika signaler och olika</p><p>transformer. Vi studerar maskinvibrationer i LabView och beslutar att 5 kHz</p><p>sampling räcker för att fånga intressanta vibrationer. Vi jämför transformers</p><p>egenskaper och beräkningskrav och väljer Fouriertransform som analysmetod.</p><p>Vi beräknar att en Atmel ARM SAM7S256 kan utföra uppgiften och</p><p>implementerar interruptbaserad signalsampling, frekvensanalys och en</p><p>beslutsrutin som resulterar i en utsignal med statusinformation.</p> / <p>In this project we examine the possibility to create a machine activity sensor by</p><p>a one-chip computer that measures a machines vibrations through an</p><p>accelerometer. The sensor shall generate a status signal. The accelerometer is</p><p>used to give a measurable signal of a machines vibrations. The one-chip</p><p>computer is used to sampel, transform and analyze this signal and generate a</p><p>status signal. With LabView we can save, study and analyze different signals</p><p>and their different transforms. By studying machine vibrations in LabView we</p><p>decide that sampling at 5 kHz is sufficient. By comparing different</p><p>transformations in regards to performance and calculation needs we choose</p><p>Fast Fourier Transform as analyzing tool. We calculate that a ARM</p><p>SAM7S256 can manage the task and implement an interrupt based sampling,</p><p>frequency analysis and decision making routine which results in a status signal.</p>
166

Laser assisted telerobotic control for remote manipulation activities

Khokar, Karan 01 June 2009 (has links)
The effort in this work has been to innovatively use range information from a laser sensor mounted on the end effector of a remote robotic arm in a telerobotic system to assist the user in carrying out remote tasks in unstructured environments. Assistance is provided in the form of Traded Supervisory Control where the human is involved in high level activities such as decision making and the machine generates task plans and executes tasks autonomously using laser data and machine intelligence. In this way human planning and high level decision making capabilities are combined with machine computational and precision task execution capabilities in an optimal way. Laser range data has been used in a novel way to generate trajectories and virtual constraints that assist the user either by executing trajectories autonomously or by guiding the user in teleoperation along specific virtual constraints. The ability of the laser to generate path plans and execute them autonomously, and generate 3D geometry information is another novel feature of the project. This has been achieved without using sophisticated sensory suite and extensive computer processing. The user simply points to certain locations in the unstructured environment by teleoperating the remote arm using the master arm and presses certain keys on the keyboard. The machine using laser data and its intelligence generates the appropriate trajectories, virtual geometric surfaces and path plans which assist the user in executing the task. Time and accuracy results in executing a remote manipulation tasks on a real-time telerobotic system with master and slave arms, with and without laser based assistance have been generated and compared to validate the hypothesis that laser based assistance improves task performance and reduces the cognitive load on the user. To improve dexterity of the arm and to enable smooth and stable control of the arm, singularity avoidance techniques have been implemented and results in simulation have been presented. Accuracy results to validate the motion control algorithms of the robot by comparing trajectories in simulation and on the robot have been generated.
167

The effects of age- and training-related changes in tendon stiffness on muscular force production and neuro-motor control during childhood

Waugh, Charlotte January 2011 (has links)
The research described in this thesis examined age- and strength training-related changes in Achilles tendon stiffness and plantarflexor force production in prepubertal children. The measurement of both Achilles tendon stiffness and muscular force production requires in vivo moment arm lengths to be known. Currently, this is possible only by using expensive and time-consuming medical imaging methodologies. Therefore, the predictability of the Achilles tendon moment arm from surface anthropometric measurements was assessed in the first experimental study (Chapter 3). The results demonstrated that a combination of foot length and the distance between the calcaneal tuberosity and 1st metatarsal head could explain 49% of the variability in Achilles tendon moment arm length in 5 – 12 year-old children. This was considered to be unacceptable for further use, thus an ultrasound-based method was decided upon for obtaining moment arm length in subsequent experimental studies. In the second and third experimental studies (Chapters 4 and 5), age-related changes in tendon mechanical and structural properties were documented and their relationship with changes in force production ability were examined in prepubertal children (5 – 12 years) and adult men and women. In Chapter 4, Achilles tendon stiffness was shown to increase with age through to adulthood, and that changes in tendon stiffness were strongly and independently associated with body mass (R2 = 0.58) and peak force production capacity (R2 = 0.51),which may provide the tendon with an increasing mechanical stimulus for growth and microadaptation. These increases in tendon stiffness were associated with a greater increase in tendon CSA (~105%) than that found for tendon length (~60%), in addition to an increase in Young’s modulus (~139%), suggesting that gross increases in tendon size as well as changes in its microstructure underpinned the increase in stiffness. In Chapter 5, the relationships between Achilles tendon stiffness and both electro-mechanical delay (EMD) and rate of force development (RFD) were determined during maximal isometric plantarflexion contractions. Moderate correlations were found between tendon stiffness and both EMD (r = -0.66) and RFD (r = 0.58). RFD was significantly better predicted when muscle activation (estimated as the rate of EMG rise) was included in a regression model. These data clearly show that increases in tendon stiffness with age through to adulthood are associated with decreases in EMD and increases in RFD, and that the rate of muscle activation has an additional influence on RFD during growth. Given that 1) Achilles tendon stiffness was lower in children than adults, 2) this lower stiffness was associated with a longer EMD and slower RFD, and 3) that strength training in adults had previously been shown to increase tendon stiffness and RFD, the adaptability of the developing Achilles tendon to a resistance training programme, and consequence of the potential changes on force production capacity were examined in the final experimental study (Chapter 6). Significant increases in Achilles tendon stiffness and Young’s modulus were found after 10 weeks of twice-weekly plantarflexor strength training in 8-9 year-old boys and girls, which demonstrates that the larger muscle force production provided a sufficient stimulus for tendon microadaptation. The training also resulted in a decrease in EMD, which was moderately correlated with the change in tendon stiffness (r = 55), but no change in RFD. Thus, the increasing tendon stiffness with training was associated with a decreasing EMD, but had no detectable effect on RFD. This would likely have a significant effect on the performance of tasks requiring rapid muscle force production. Together, the results of the present series of investigations demonstrate that the tendon loading experienced from both normal ageing and overloading (strength training) can increase tendon stiffness in children, and that these changes have a detectable effect on rapid force production.
168

Internal Representations for the Generalization of Motor Memories

Brayanov, Jordan Brayanov 14 March 2013 (has links)
Movement and memory are two of the most fundamental components of our existence. From the moment of birth, we rely on a variety of movements to interact with people and objects around us, and as we grow, we continuously form new motor memories to improve the fidelity of these interactions by exploring and learning more about our environment, especially in unfamiliar situations, ultimately becoming better equipped to handle novel and unknown environments. In this dissertation, we explore four facets of motor memory associated with voluntary movement and postural control in the upper limbs: (1) Optimal motor memory formation via sensorimotor integration. We ask whether the motor system combines prior memories with new sensory information to produce statistically-optimal weight estimates. We find that the weight estimate that the motor system makes in order to re-stabilize one’s arm posture when an object is rapidly removed from the hand that supports it, reflected information integration in a Bayesian, statistically-optimal fashion. Remarkably, we demonstrate that when experiencing the well-known size-weight illusion, the motor and perceptual system’s weight estimates are biased in opposite directions, suggesting two divergent modes for information integration within the central nervous system. (2) Movement features important for the learning and generalization of motor memories. We show that, velocity-dependent adaptation generalizes across different movements, even from discrete straight point-to-point to continuous circular movements, however the amount of generalization is limited and context-dependent. In a series of experiments, we quantified the contributions of different movement features to the elicited adaptation transfer. In particular, we show that other movement states (i.e. position and acceleration) make only minor contributions whereas, the contexts provided by movement geometry and movement continuity are critical. (3) Internal representation of motor memories in intrinsic-extrinsic coordinates. We show that motor memories are based not on fully intrinsic or extrinsic representations but on a gain-field (multiplicative) combination the two. This gain-field representation generalizes between actions by effectively computing movement similarity based on the Mahalanobis distance across both intrinsic and extrinsic coordinates, in line with neural recordings showing mixed intrinsic-extrinsic representations in motor and parietal cortices. (4) Motor memories with local and global generalization. We demonstrate the existence of two distinct components of motor memory displaying different generalization footprints: One generalizes only locally, around the trained movement direction and with the trained end-effector, whereas the other generalizes broadly across both., We proceed to show that broad generalization results from a rapidly-learning adaptive process, dominates on easier-to-learn tasks, and performs high-level processing, producing adaptation vectors that integrate multiple sources of information, in line with a recent theory for perceptual learning. / Engineering and Applied Sciences
169

Ανάπτυξη διάταξης βιομηχανικής όρασης για προσδιορισμό θέσης και προσανατολισμού κινούμενων αντικειμένων και οδήγηση ρομποτικού βραχίονα

Κανελλάκης, Χριστόφορος, Κυρίτσης, Γεώργιος 16 April 2015 (has links)
Ο πρωταρχικός στόχος αυτής της εργασίας είναι η υλοποίηση μιας βιομηχανικής διάταξης σε εργαστηριακή κλίμακα στην οποία να συνεργάζονται ένα στερεοσκοπικό σύστημα και ένας ρομποτικός βραχίονας. Πιο συγκεκριμένα, η διαδικασία χωρίζεται σε δύο μέρη, την αναγνώριση στο χώρο των επιθυμητών αντικειμένων και την οδήγηση βάση αυτής του ρομποτικού βραχίονα. Για το πρώτο μέρος έγινε χρήση της βιβλιοθήκης OpenCV σε γλώσσα C++ και ως στερεοσκοπικό υλικό χρησιμοποιήθηκαν δύο παράλληλα διατεταγμένες κάμερες τύπου webcam. Η διαδικασία που ακολουθήθηκε για την αναγνώριση θέσης χωρίστηκε σε αρκετά βήματα. Αρχικά δημιουργήθηκε ένα πρόγραμμα το οποίο αποθηκεύει καρέ από τις δύο κάμερες στα οποία απεικονίζεται ένα μοτίβο βαθμονόμησης. Στη συνέχεια, αυτές οι εικόνες εισάγονται στον κώδικα βαθμονόμησης με στόχο να υπολογιστούν οι εγγενείς και εξωγενείς παράμετροι των καμερών. Έπειτα, με τη χρήση των παραμέτρων αυτών και τη θεωρία της επιπολικής γεωμετρίας μπορεί να γίνει η αναγνώριση θέσης ενός αντικειμένου στο χώρο. Τέλος, χρησιμοποιείται ένας αλγόριθμος εντοπισμού του κέντρου ενός αντικειμένου στην οθόνη με βάση το χρώμα έτσι ώστε να καθοριστεί για ποιο αντικείμενο ο αλγόριθμος θα υπολογίσει τη θέση. Στο δεύτερο μέρος χρησιμοποιήθηκε ο ρομποτικός βραχίονας Katana s400 6M90G της εταιρείας Neuronics, ο οποίος προγραμματίστηκε σε γλώσσα C++, σε περιβάλλον Visual Studio 2008. Αρχικά, βρέθηκαν οι γωνίες Euler της αρπάγης, για διαφορετικές προσεγγίσεις του προσανατολισμού της. Με τον συνδυασμό των συντεταγμένων του αντικειμένου, που βρίσκονται από το στερεοσκοπικό σύστημα καθοδηγείται το Katana ώστε να το πιάσει. Τα πειράματα που διεξαχθήκαν περιλάμβαναν την αρπαγή στάσιμων αντικειμένων με γενικό και οριζόντιο προσανατολισμό εργαλείου. Τέλος, πραγματοποιήθηκαν πειράματα με αντικείμενα εν κινήσει, τυχαίας θέσης με γενικό, κάθετο και οριζόντιο προσανατολισμό αρπάγης. / The primary objective of this thesis is the implementation of an industrial system at laboratory scale in which a stereo system collaborates with a robotic arm. More specifically, the process is divided into two parts, the recognition of the desired objects and the manipulation of the robotic arm. In the first part were used the OpenCV library, in C ++ language and two parallel web-cameras. The procedure for the recognition of the objects, was divided into several steps. Initially a number of images were inserted in the calibration algorithm in order to estimate the intrinsic and extrinsic camera parameters. Then, using these parameters and the epipolar geometry it was possible to recognize the position of an object in 3D space. Finally, an algorithm is used to locate the center of an object on the screen by color in order to determine for what object the algorithm will calculate the position. In the second part was used the robotic arm Katana s400 6M90G by Neuronics, programmed in C ++, in Visual Studio 2008. Initially, the Euler angles of the gripper for different orientations were found. Given the coordinates of the objects, provided by the stereo system, the Katana arm was guided to grasp them. The experiments that were conducted included the grasping of stationary objects in a general and horizontal orientation of the Katana tool. Finally, experiments were performed with objects in motion and random position in general, vertical and horizontal orientation of the gripper.
170

Strategies for exercise assessment and training in patients with chronic obstructive pulmonary disease

Janaudis-Ferreira, Tania January 2010 (has links)
Rationale: Chronic obstructive pulmonary disease (COPD) is not only a common lung disease but is a major cause of morbidity and mortality worldwide. Pulmonary rehabilitation (PR) helps optimize function and independence by increasing exercise capacity, reducing symptoms and improving health related quality of life (HRQL). Exercise training is certainly a key component of the PR programs; however, many of its aspects still need to be better defined such as optimal exercise assessment and training modality for these patients. The general purpose of this thesis was to generate new knowledge that could contribute to new strategies for exercise assessment and training in patients with COPD. Methods and results: This thesis is comprised of four independent studies. Thigh muscle strength, endurance and fatigue were compared between 42 patients with moderate to severe COPD and 53 healthy controls (Study I). Impaired thigh muscle strength and endurance in patients with COPD was found, except for muscle strength in knee extension in male patients. Female patients had higher fatigue index than female controls while no difference was found between male patients and controls. The six-minute walk test (6MWD) performed on a non-motorized treadmill (6MWD-T) was compared with the 6MWD performed in a corridor (6MWD-C) in 16 healthy elderly subjects (Study II). They performed twelve tests (six 6MWD-C and six 6MWD-T) on two different days in a randomized order. An average discrepancy was found between the two methods with the subjects walking a shorter distance on the non-motorized treadmill. However, the results showed good test-retest reliability between days and test repetitions. A systematic review (Study III) was done of studies that investigated the effects of an arm training program in patients with COPD. The findings of this review indicated that there is evidence that an arm training program improves arm exercise capacity, but its effects on dyspnea, arm fatigue and healthy-related quality of life is unclear. Finally, a two-armed randomized controlled trial examined the effects of an arm training program on arm function, arm exercise capacity, muscle strength, symptoms and HRQL in patients with COPD (Study IV). The groups were randomized to arm training or sham. Compared with the changes observed in the control group, the magnitude of change in the intervention group was greater for arm function, arm exercise capacity and muscle strength. There was no difference between groups in HRQL or symptoms. Conclusions: Upper extremity resistance training improves arm exercise capacity, arm function and muscle strength in patients with COPD. Training and assessment of upper and lower limb muscles should be included into PR programs. The 6MWD performed on a non-motorized treadmill may offer an alternative option to the standard 6MWD when a 30-meter corridor is not available.

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