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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.
11

Zero Tolerance Program : A strategic approach to reduce operational cost and improve quality levels

Pettersson, Anna-Lena January 2010 (has links)
<p>For a company to be competitive today, one way is to create a natural feedback loop from the production department to the design department with information regarding the production systems ability to deliver a finished component. The purpose with this feedback loop is to create respect for tolerances and to more design for manufacturing and assembly. The studied company in this thesis work developed a quality program to reach a spiral of continuous improvements to reduce cost of poor quality (CoPQ) and to reach an improved quality level (PPM). The object of this work was to test and improve the quality program called The Zero Tolerance Program. Delimitations were made when the work was started and ongoing which led to that the impact on PPM could not be studied. The connection to CoPQ was difficult to obtain and could only be proved theoretically, not practically, due to the short timetable.</p><p>During the short amount of time the right root cause could not be found. The thesis work findings came to a number of identified Measurable Success Criteria and requirements which must be in place for the further progress of The Zero Tolerance Program.</p> / PREPARE
12

Toleranzmanagement in der Konstruktion mit sich ändernden Normen

Bruns, Christoph 08 May 2014 (has links) (PDF)
Neue Normenkonzepte nach ISO /TR 14638 zwingen Unternehmen sich neu zu orientieren, um normgerechtes und wertschöpfendes Toleranzmanagement durchzuführen. INNEO-Produkte können dabei helfen.
13

APPLICATION OF ASPHERICS FOR WEIGHT REDUCTION IN SELECTED CATADIOPTRIC LENSES

Buchroeder, Richard A. 07 1900 (has links)
QC 351 A7 no. 69 / The history of modern wide -field, high-speed catadioptric lenses is reviewed. One system comprising only spherical curves and representative of the current art for low-light-level systems is evaluated and used as a baseline design in a weight-reduction study. Five aspheric designs are computed and evaluated. It is found that the use of aspherics will permit weight reduction only in certain instances, i.e., if one element of an all-spherical design can be eliminated or if a fundamentally different configuration that is possible only with aspherics is substituted for the all-spherical configuration. Of these possibilities, the elimination of an element is the best replacement for the baseline design. The case of a highly constrained, purely refractive triplet is studied in some detail. Four designs are computed -from the all-spherical case to the most complex polynomial aspheric. It is found that, if only conic aspherics are employed, significant improvement can be obtained and the problems involved are sensibly the same as those in all-spherical designs. When complex aspherics are applied, the problem becomes surprisingly difficult, and there is some indication that a computer can deal with it better than can a human lens designer.
14

Zero Tolerance Program : A strategic approach to reduce operational cost and improve quality levels

Pettersson, Anna-Lena January 2010 (has links)
For a company to be competitive today, one way is to create a natural feedback loop from the production department to the design department with information regarding the production systems ability to deliver a finished component. The purpose with this feedback loop is to create respect for tolerances and to more design for manufacturing and assembly. The studied company in this thesis work developed a quality program to reach a spiral of continuous improvements to reduce cost of poor quality (CoPQ) and to reach an improved quality level (PPM). The object of this work was to test and improve the quality program called The Zero Tolerance Program. Delimitations were made when the work was started and ongoing which led to that the impact on PPM could not be studied. The connection to CoPQ was difficult to obtain and could only be proved theoretically, not practically, due to the short timetable. During the short amount of time the right root cause could not be found. The thesis work findings came to a number of identified Measurable Success Criteria and requirements which must be in place for the further progress of The Zero Tolerance Program. / PREPARE
15

Dynamic Modeling And Analysis Of Vibration Effects On Performance In Optical Systems

Avsar, Ahmet Levent 01 August 2008 (has links) (PDF)
In order to understand the effects of structurally induced line of sight (SILOS) jitter (vibration) and to predict its effects on optical system performance, a simple and practical vibratory model and software are developed by using discrete and finite element modeling techniques. For an existing simple optical system, discrete and FE dynamic models are constructed and they are validated by modal tests for the frequency range of interest. In order to find material properties of adhesive, which is used in optical system, a simple test is constructed and these properties are found by using a single degree of freedom model. The effects of vibration on the system performance are investigated under random vibration load conditions by using the software developed. It is concluded that the analytical model suggested can successfully be used in preliminary design stage of a simple optical system when the optical housing and lens behave rigidly in the frequency range of interest. The optical performance prediction software combines the optical element tolerances and displacements in order to determine the optical performance.
16

An investigation of the measurement accuracy and productivity of a Waratah HTH 625c Processor Head

Saathof, David January 2014 (has links)
Log processor heads have become increasingly used in New Zealand (NZ) forest harvesting operations to increase productivity and improve worker safety. Information regarding the measurement accuracy and productivity of new model processor heads is limited. As a result, log quality control (QC) is carried out on logs that have been merchandised by a processor head. This task can have a high risk for injury from man – machine interaction. A trend between studies was that older model Waratah’s did not have sufficient measurement accuracy to alleviate the requirement for log QC. In this study, a Waratah HTH 625c processor head operating in NZ was analysed for measurement accuracy and productivity. Measurement accuracy was considered by measuring logs for length, diameter and branch size. A comparison of two methods of processing was also considered to determine measurement accuracy, productivity and production efficiency for the way logs are delimbed and merchandised. Once gathered, the data was then analysed to identify significant effects, trends and relationships between variables. Length measurements were highly accurate but diameter measurements were under- estimated. It was also evident that although there was absolute accuracy, there was a high variability in measurements with underestimating and overestimating. Branch size was also found to have a significant impact in reducing length measurement accuracy and productivity. Single pass processing has significantly higher production efficiency than two pass processing, although single pass processing had a higher length error associated with it. The Waratah HTH 625c processor head has better measurement accuracy than older model Waratah’s. However, logs are still cut out-of-spec which will require a log QC to identify. As measurement technology is further improved in processor heads, and improvements to NZ’s plantation resource (improved form and smaller branching) are realised at harvest age, measurement accuracy and productivity of log processor heads will further improve.
17

A Comparison and Outline of Tolerances in Performing Optical Time Division Multiplexing using Electro-Absorption Modulators

Owsiak, Mark 18 May 2010 (has links)
As high bandwidth applications continue to emerge, investigation in technologies that will increase transmission capacity become necessary. Of these technologies, Optical Time Division Multiplexing (OTDM) has been presented as a possible solution, supporting a next generation bit rate of 160 Gbit/s. To perform the demultiplexing task, the use of tandem electro-absorption modulators (EAMs) has been widely studied, and due to its benefits was chosen as the topology of this thesis. To create an effective model of an OTDM system, the vector based mathematical simulation tool MatLab is used. Care was taken to create an accurate representation of an OTDM system, including: the development of a realistic pulse shape, the development of a true pseudo-random bit sequence in all transmitted channels, the optimization of the gating function, and the representation of system penalty. While posing impressive bit rates, various sources of system performance degradation pose issues in an OTDM system, owning to its ultra-narrow pulse widths. The presence of dispersion, timing jitter, polarization mode dispersion, and nonlinear effects, can sufficiently degrade the quality of the received data. This thesis gives a clear guideline to the tolerance an OTDM system exhibits to each of the aforementioned sources of system penalty. The theory behind each impairment is thoroughly discussed and simulated using MatLab. From the simulated results, a finite degree of sensitivity to each source of system penalty is realized. These contributions are of particular importance when attempting to implement an OTDM system in either the laboratory, or the field. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2010-05-17 22:51:56.471
18

Standardization of CMM Algorithms and Development of Inspection Maps for Geometric Tolerances

January 2011 (has links)
abstract: The essence of this research is the reconciliation and standardization of feature fitting algorithms used in Coordinate Measuring Machine (CMM) software and the development of Inspection Maps (i-Maps) for representing geometric tolerances in the inspection stage based on these standardized algorithms. The i-Map is a hypothetical point-space that represents the substitute feature evaluated for an actual part in the inspection stage. The first step in this research is to investigate the algorithms used for evaluating substitute features in current CMM software. For this, a survey of feature fitting algorithms available in the literature was performed and then a case study was done to reverse engineer the feature fitting algorithms used in commercial CMM software. The experiments proved that algorithms based on least squares technique are mostly used for GD&T; inspection and this wrong choice of fitting algorithm results in errors and deficiency in the inspection process. Based on the results, a standardization of fitting algorithms is proposed in light of the definition provided in the ASME Y14.5 standard and an interpretation of manual inspection practices. Standardized algorithms for evaluating substitute features from CMM data, consistent with the ASME Y14.5 standard and manual inspection practices for each tolerance type applicable to planar features are developed. Second, these standardized algorithms developed for substitute feature fitting are then used to develop i-Maps for size, orientation and flatness tolerances that apply to their respective feature types. Third, a methodology for Statistical Process Control (SPC) using the I-Maps is proposed by direct fitting of i-Maps into the parent T-Maps. Different methods of computing i-Maps, namely, finding mean, computing the convex hull and principal component analysis are explored. The control limits for the process are derived from inspection samples and a framework for statistical control of the process is developed. This also includes computation of basic SPC and process capability metrics. / Dissertation/Thesis / M.S. Mechanical Engineering 2011
19

1. Návrh kontrolních procesů vevýrobě bezpečtnostního ventilu / Proposal of process control in production safety valve

Jaša, Aleš January 2011 (has links)
The aim of this thesis is precise definition of control processes for components of Pressure Limit Valve 5 Generation (PLV5) which is produced by Bosch Diesel Ltd. in Jihlava. The objective was to define measurement methods which ensure identical results of measurement between co. Bosch Diesel Ltd. in Jihlava and suppliers of individual components. The results of this study are introduced into control drawings and described in individual conclusions of the thesis.
20

Tolerances and Misalignment Aberrations for Electron Optical Elements and Systems / Tolerances and Misalignment Aberrations for Electron Optical Elements and Systems

Sháněl, Ondřej January 2014 (has links)
Nepřesnosti při výrobě a sestavení rotačně souměrné čočky a deflektrou a jejich přesného zařazení do elektronově optického systému se projeví jako dodatečné pole příslušné symetrie, které deformuje ideální zobrazení. Tato dodatečná pole dokážeme spočítat pomocí metody konečných prvků v programu EOD. Toleranční analýza spočívá ve stanovení požadavků na rozměry a sestavení jednotlivých prvků a jejich částí. Korekce vad seřízení pak spočívá v určení typu a polohy korekčních vychylovacích cívek a multipólů tak, aby se tyto dodatečné vady odstranily, nebo aby se minimalizoval jejich vliv. Cílem disertační práce je analýza projevů vad seřízení a chování neseřízených systémů prozařovacích elektronových mikroskopů.

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