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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.
1

Novel Escapement Mechanism using a Compliant Mechanism and a Piezoelectric Actuator

Mali, Girish Suresh 12 December 2007 (has links)
"Escapement mechanisms hold back a stream of parts driven either by mechanical or pneumatic means for a length of time and release a single part as required to an assembly station. They are used in most automatic multi-component assembly equipment. They occupy a significant design space and have dynamic characteristics of their own. This research aimed to develop a novel high speed mechanism for parts escapement that occupies less design space and contributes less to the dynamic activity of the structure. Several conceptual mechanisms were generated and evaluated. A compliant mechanism that amplifies the very small displacement of a piezo actuator was selected for detailed design. A proof of concept prototype was fabricated and tested. A piezo stack was used to bend a thin, spring steel, compliant beam. Its deflection was further amplified by attaching a comparatively rigid beam extension at the end of the compliant section. The mechanism escapes parts at 16 Hz using constrained layer damping on the beam to reduce vibrations. The concept is feasible to use on production machinery and provides advantages in terms of higher operating speeds and compactness. The concept could also be used where there is a requirement of high speed gating."
2

Exploring the Dynamics of a Mechanical Watch Lever Escapement using Finite Element Analysis

Naperkoski, Brian Michael 30 November 2022 (has links)
This thesis focuses on the development of a short-term, operationally stable finite element-based simulation of a mechanical watch lever escapement. This was accomplished in four steps: by choosing a reference escapement based on the needs of the study, by executing a reverse engineering methodology to create a lever escapement in computer-aided design (CAD) software, by capturing experimental data from the reference escapement via custom- built apparatus and then reconciling this data with an analytical model, and by using the knowledge gained from these efforts to develop an implicit dynamic simulation of a lever escapement that aimed to achieve performance metrics defined by watchmaking sources. The final version of the simulated lever escapement was able to meet two of the three performance goals defined for the study. The simulation met the primary performance goal by achieving stable operation for two seconds. During this window of stability, the simulated lever escapement met the secondary performance goal of the study by achieving timing performance metrics defined by watchmaking sources. Unfortunately, the tertiary performance goal was not met as the balance amplitude of the final simulation was outside of the target range by 5.23% when compared against the lower bound. Although the balance amplitude error of the simulated escapement would be indicative of a mechanism that needs servicing, its performance during the stability period was assessed to be representative of a functional lever escapement and therefore, its dynamics and sensitivities were explored and presented. / Master of Science / Mechanical watches rely on physics to keep accurate time. The time regulation mechanism within a mechanical watch is called an escapement, and the most widely used escapement design adopted by watchmakers is the lever escapement. While prior attempts have been made to simulate the physics that these mechanisms use to keep accurate time, achieving stable operating performance in a complete lever escapement simulation remains elusive in published studies. The examination of a stable, simulated lever escapement could reveal new insights into these mechanisms by reducing the impact of transient phenomena. This thesis focuses on the development of a short-term, operationally stable simulation of a lever escapement mechanism. This was achieved by developing a model of a real-world lever escapement, by capturing experimental data to improve the model, and then by applying the knowledge gained from these efforts to create a dynamic simulation in Abaqus/CAE. The final simulation was able to meet two of the three performance goals defined for the study, which proved that it is possible to create a simulation of a lever escapement. Furthermore, the study revealed unexpected phenomena that may be present in real-world lever escapements and may affect their performance.
3

The extent of hatchery-origin fish among fall chinook salmon (Onchorhynchus tshawytscha) observed in South Puget Sound tributary streams

Kennedy, Kevin M. January 2008 (has links) (PDF)
Thesis (M.E.S.)--The Evergreen State College, 2008. / Title from title screen (viewed 2/25/2010). Includes bibliographical references (leaves 95-101).
4

Analyse und Berechnung von Uhrwerkskomponenten in mechanischen Kleinuhren

Röseler, Benjamin 12 January 2016 (has links) (PDF)
Die steigende Nachfrage nach mechanischen Kleinuhren und deren monopolhafte, meist in Schweizer Unternehmen erfolgte Fertigung der Uhrenkomponenten, führten zu einem stetig zunehmenden Interesse, historisch gewachsene handwerkliche Vorgaben und Vorschriften zu hinterfragen. Genauere Fertigungstechnologien, die Verwendung neuerer Materialien und die Möglichkeit des Einsatzes heutiger Rechentechnik bei der Auslegung und Qualitätssicherung, welche beispielsweise in der Feinwerktechnik, dem Maschinenbau oder der Fahrzeugtechnik seit Jahren Stand der Technik sind, führen zu Forschungsaufgaben mit der Möglichkeit, ermittelte theoretische Ergebnisse mit reichlich handwerklichen Erfahrungen der Uhrmacher zu stützen. Das Interesse, die Funktionsweise der einzelnen Teilsysteme im Uhrwerk genau zu analysieren, Möglichkeiten der Anpassung sowohl fertigungsbedingt als auch wirkungsgrad- und genauigkeitssteigernd aufzuzeigen und zu definieren führte zur Anfertigung dieser Arbeit. Mit dieser Arbeit wird ein Beitrag geschaffen, welcher das systematische Vorgehen bei der Analyse und der Berechnung der Uhrwerkskomponenten Räderwerk und Schweizer Ankerhemmung beschreibt. Es werden theoretische Untersuchungen aufgeführt, Optimierungsparameter herausgestellt und Messungen an realen Uhrwerken durchgeführt, insbesondere zur Validierung der theoretischen Untersuchungen. Mit der Auswertung der Messergebnisse werden Möglichkeiten gezeigt, geometrische und kinematische Problemstellungen zu identifizieren und gezielt anzupassen.
5

Analyse und Berechnung von Uhrwerkskomponenten in mechanischen Kleinuhren

Röseler, Benjamin 14 December 2015 (has links)
Die steigende Nachfrage nach mechanischen Kleinuhren und deren monopolhafte, meist in Schweizer Unternehmen erfolgte Fertigung der Uhrenkomponenten, führten zu einem stetig zunehmenden Interesse, historisch gewachsene handwerkliche Vorgaben und Vorschriften zu hinterfragen. Genauere Fertigungstechnologien, die Verwendung neuerer Materialien und die Möglichkeit des Einsatzes heutiger Rechentechnik bei der Auslegung und Qualitätssicherung, welche beispielsweise in der Feinwerktechnik, dem Maschinenbau oder der Fahrzeugtechnik seit Jahren Stand der Technik sind, führen zu Forschungsaufgaben mit der Möglichkeit, ermittelte theoretische Ergebnisse mit reichlich handwerklichen Erfahrungen der Uhrmacher zu stützen. Das Interesse, die Funktionsweise der einzelnen Teilsysteme im Uhrwerk genau zu analysieren, Möglichkeiten der Anpassung sowohl fertigungsbedingt als auch wirkungsgrad- und genauigkeitssteigernd aufzuzeigen und zu definieren führte zur Anfertigung dieser Arbeit. Mit dieser Arbeit wird ein Beitrag geschaffen, welcher das systematische Vorgehen bei der Analyse und der Berechnung der Uhrwerkskomponenten Räderwerk und Schweizer Ankerhemmung beschreibt. Es werden theoretische Untersuchungen aufgeführt, Optimierungsparameter herausgestellt und Messungen an realen Uhrwerken durchgeführt, insbesondere zur Validierung der theoretischen Untersuchungen. Mit der Auswertung der Messergebnisse werden Möglichkeiten gezeigt, geometrische und kinematische Problemstellungen zu identifizieren und gezielt anzupassen.
6

Counting on their migration home: an examination of monitoring protocols and Saanich First Nations’ perspectives of Coho (Oncorhynchus kisutch), Chinook (O. tshawytscha) and Chum (O. keta) Pacific Salmon at Goldstream River and Saanich Inlet, Southern Vancouver Island, British Columbia

Paul, Roxanne 20 August 2007 (has links)
Records of abundance of salmon that return to their natal spawning stream (escapements) are important indices that can assist with monitoring, conservation, and management of a salmon population over time. On their own, however these data reveal very little about the habitat, ecosystem and human communities that salmon encounter on their journey from freshwater to sea and back again. This research examines monitoring protocols for Goldstream River salmon stocks (coho, chinook and chum Pacific salmon). It includes and reaches beyond biostatistics from stream surveys to gauge First Nations’ artisanal fishing activities at Goldstream River and Saanich Inlet as well as their commercial chum fishing endeavours in Saanich Inlet on south Vancouver Island, British Columbia. Methods included summations of major themes from interviews on traditional ecological knowledge (TEK) shared by local Saanich First Nation fishers whose families have lived in the communities around Goldstream River and Saanich Inlet for more than 200 years. Analyses of Goldstream salmon escapements for the period 1932 to 2004 and native harvest statistics of chum caught from Saanich Inlet between 1982 and 2004 are integrated with results from analysis of TEK research undertaken for this project. Key recommendations arising from the results of this research are: stream habitat restoration in response to loss and degradation of salmon-bearing streams; modification of stream survey procedures to measure for morphological and physiological attributes including indicators of the health of Goldstream salmon; monitoring and eliminating sources of pollution to Saanich Inlet waters; implementing precautionary measures to ensure that overfishing of Goldstream salmon and shrimp in Saanich Inlet does not recur; and safeguarding naturally abundant Goldstream chum populations at the river. Under current management of the Goldstream chum fishery, the maximum carrying capacity (K) or target escapement of chum that the Goldstream River spawning grounds sustain is 15,000. Based on population assessments as well as physiography and ecosystem dynamics, I infer that Goldstream River’s K for its natural chum population is between ~16,000 and 18,000; ~1,500 for the mixed stocks of natural and hatchery enhanced coho; and ~50 for chinook (based on the river’s naturally occurring populations between 1932 and 1973) or ~385 enhanced chinook (based on the returning population from 1975 to 2002 since hatchery enhancement took place). A co-management relationship exists between Fisheries and Oceans Canada (DFO) resource managers and the Saanich First Nations bands (Saanich Tribal Fisheries councilors). Improvements to communication, collaboration and information sharing between DFO resource managers, Goldstream hatchery operators and Saanich First Nations with regards to decisions made about Goldstream salmon stocks are, however, necessary. In this thesis, I propose a model with recommendations for compatible fisheries management goals and techniques including adaptive management and ecosystem-based management to address this problem.
7

Counting on their migration home: an examination of monitoring protocols and Saanich First Nations’ perspectives of Coho (Oncorhynchus kisutch), Chinook (O. tshawytscha) and Chum (O. keta) Pacific Salmon at Goldstream River and Saanich Inlet, Southern Vancouver Island, British Columbia

Paul, Roxanne 20 August 2007 (has links)
Records of abundance of salmon that return to their natal spawning stream (escapements) are important indices that can assist with monitoring, conservation, and management of a salmon population over time. On their own, however these data reveal very little about the habitat, ecosystem and human communities that salmon encounter on their journey from freshwater to sea and back again. This research examines monitoring protocols for Goldstream River salmon stocks (coho, chinook and chum Pacific salmon). It includes and reaches beyond biostatistics from stream surveys to gauge First Nations’ artisanal fishing activities at Goldstream River and Saanich Inlet as well as their commercial chum fishing endeavours in Saanich Inlet on south Vancouver Island, British Columbia. Methods included summations of major themes from interviews on traditional ecological knowledge (TEK) shared by local Saanich First Nation fishers whose families have lived in the communities around Goldstream River and Saanich Inlet for more than 200 years. Analyses of Goldstream salmon escapements for the period 1932 to 2004 and native harvest statistics of chum caught from Saanich Inlet between 1982 and 2004 are integrated with results from analysis of TEK research undertaken for this project. Key recommendations arising from the results of this research are: stream habitat restoration in response to loss and degradation of salmon-bearing streams; modification of stream survey procedures to measure for morphological and physiological attributes including indicators of the health of Goldstream salmon; monitoring and eliminating sources of pollution to Saanich Inlet waters; implementing precautionary measures to ensure that overfishing of Goldstream salmon and shrimp in Saanich Inlet does not recur; and safeguarding naturally abundant Goldstream chum populations at the river. Under current management of the Goldstream chum fishery, the maximum carrying capacity (K) or target escapement of chum that the Goldstream River spawning grounds sustain is 15,000. Based on population assessments as well as physiography and ecosystem dynamics, I infer that Goldstream River’s K for its natural chum population is between ~16,000 and 18,000; ~1,500 for the mixed stocks of natural and hatchery enhanced coho; and ~50 for chinook (based on the river’s naturally occurring populations between 1932 and 1973) or ~385 enhanced chinook (based on the returning population from 1975 to 2002 since hatchery enhancement took place). A co-management relationship exists between Fisheries and Oceans Canada (DFO) resource managers and the Saanich First Nations bands (Saanich Tribal Fisheries councilors). Improvements to communication, collaboration and information sharing between DFO resource managers, Goldstream hatchery operators and Saanich First Nations with regards to decisions made about Goldstream salmon stocks are, however, necessary. In this thesis, I propose a model with recommendations for compatible fisheries management goals and techniques including adaptive management and ecosystem-based management to address this problem.

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