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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.
31

Methods for the analysis of ordinal response data in medical image quality assessment

Keeble, C., Baxter, P.D., Gislason-Lee, Amber J., Treadgold, L.A., Davies, A.G. 12 April 2016 (has links)
Yes / The assessment of image quality in medical imaging often requires observers to rate images for some metric or detectability task. These subjective results are used in optimization, radiation dose reduction or system comparison studies and may be compared to objective measures from a computer vision algorithm performing the same task. One popular scoring approach is to use a Likert scale, then assign consecutive numbers to the categories. The mean of these response values is then taken and used for comparison with the objective or second subjective response. Agreement is often assessed using correlation coefficients. We highlight a number of weaknesses in this common approach, including inappropriate analyses of ordinal data and the inability to properly account for correlations caused by repeated images or observers. We suggest alternative data collection and analysis techniques such as amendments to the scale and multilevel proportional odds models. We detail the suitability of each approach depending upon the data structure and demonstrate each method using a medical imaging example. Whilst others have raised some of these issues, we evaluated the entire study from data collection to analysis, suggested sources for software and further reading, and provided a checklist plus flowchart for use with any ordinal data. We hope that raised awareness of the limitations of the current approaches will encourage greater method consideration and the utilization of a more appropriate analysis. More accurate comparisons between measures in medical imaging will lead to a more robust contribution to the imaging literature and ultimately improved patient care. / EU-funded PANORAMA project, funded by grants from Belgium, Italy, France, Netherlands, UK and the ENIAC Joint Undertaking.
32

Impacts of Professional Development on Elementary Mathematics Teachers' Implementation of Cognitively Demanding Tasks

Porras Monroy, Maria 01 January 2024 (has links) (PDF)
This study provided insight into the impact a professional development series on cognitively demanding tasks had on teachers’ identification and implementation of tasks, as well as, determined which aspects of the professional development were beneficial to participants’ understanding of cognitively demanding tasks. The professional development included five sessions and was centered on the Instructional Quality Assessment (IQA) Potential of the Task and Implementation of the Task Rubrics (Boston et al., 2019). As part of the study, participants submitted tasks and student artifacts pre and post professional development. The investigation included an analysis of tasks, student artifacts, and a thematic analysis of collaborative conversations and interviews. A single case study was conducted, with the case being the professional development series. Additionally, case participants provided insights on their experiences and learning on cognitively demanding tasks. Findings suggested that there was an impact on participants’ implementation of cognitively demanding tasks after they participated in the professional development series. Throughout the thematic analysis, aspects of the professional development were identified as beneficial to participants’ learning and understanding of cognitively demanding tasks. Discussion of the findings in relation to the current literature and their implications were provided. Additional research was suggested to continue the professional development series with the IQA Teachers’ Questions, Teacher’s Linking, and Teacher’s Press Rubrics (Boston et al., 2019) which follow the IQA progression. Further research into the complexity of schools under heightened state or county supervision should be investigated in regard to professional development and teacher autonomy. These findings add to the literature and research in the field of mathematics education, cognitively demanding tasks, and professional development.
33

Implementation and Evaluation of P.880 Methodology

Imam, Hasani Syed Hassan January 2009 (has links)
Continuous Evaluation of Time Varying Speech Quality (CETVSQ) is a method of subjective assessment of transmitted speech quality for long speech sequences containing quality fluctuations in time. This method is modeled for continuous evaluation of long speech sequences based on two subjective tasks. First task is to assess the speech quality during the listening and second task is to assess the overall speech quality after listening to the speech sequences. The development of continuous evaluation of time varying speech quality was motivated by fact that speech quality degradations are often not constant and varies in time. In modern IP telephony and wireless networks, speech quality varies due to specific impairments such as packet loss, echo, handover in networks etc. Many other standard methods already exist, which are being used for subjective assessment of short speech sequences. These methods such as ITU-T Rec. P.800 are well suited for only time constant speech quality. In this thesis work, it was required to implement CETVSQ methodology, so that it could be possible to assess long speech sequences. An analog hardware slider is used for the continuous assessment of speech qualities, as well as for overall quality judgments. Instantaneous and overall quality judgments are being saved into Excel file. The results stored in the Excel file are analyzed by applying different statistical measures. In evaluation part of the thesis work, subjects’ scores are analyzed by applying statistical methods to identify several factors that have originated in the CETVSQ methodology. A subjective test had already been conducted according to P.800 ACR method. The long speech sequences were divided into 8 seconds short sequences and then assessed using P.800 ACR method. In this study, the long speech sequences are assessed using CETVSQ methodology and comparison is conducted between P.800 ACR and CETVSQ results. It has been revealed that if long speech sequences are divided into short segments and evaluated using P.800 ACR, then P.800 ACR results will be different from the results obtained from CETVSQ methodology. The necessity of CETVSQ methodology is proved by this study.
34

Towards model governance in predictive toxicology

Palczewska, Anna Maria, Fu, X., Trundle, Paul R., Yang, Longzhi, Neagu, Daniel, Ridley, Mick J., Travis, Kim January 2013 (has links)
no / Efficient management of toxicity information as an enterprise asset is increasingly important for the chemical, pharmaceutical, cosmetics and food industries. Many organisations focus on better information organisation and reuse, in an attempt to reduce the costs of testing and manufacturing in the product development phase. Toxicity information is extracted not only from toxicity data but also from predictive models. Accurate and appropriately shared models can bring a number of benefits if we are able to make effective use of existing expertise. Although usage of existing models may provide high-impact insights into the relationships between chemical attributes and specific toxicological effects, they can also be a source of risk for incorrect decisions. Thus, there is a need to provide a framework for efficient model management. To address this gap, this paper introduces a concept of model governance, that is based upon data governance principles. We extend the data governance processes by adding procedures that allow the evaluation of model use and governance for enterprise purposes. The core aspect of model governance is model representation. We propose six rules that form the basis of a model representation schema, called Minimum Information About a QSAR Model Representation (MIAQMR). As a proof-of-concept of our model governance framework we develop a web application called Model and Data Farm (MADFARM), in which models are described by the MIAQMR-ML markup language. (C) 2013 Elsevier Ltd. All rights reserved.
35

Gehaltebeheer binne interne ouditfunksies en die toepassing daarvan in Suid-Afrika

Marais, Marinda 30 June 2003 (has links)
The purpose of quality control within internal auditing functions is to ensure that internal auditing functions add value by providing a quality service. The aim of this research project was to investigate the importance of quality control within internal auditing functions as prescribed by the standards and guidelines of the internal auditing profession. It was also attempted to determine to what extent these standards and guidelines are applied within internal auditing functions in South Africa. The study concluded that quality control is not adequately applied within all internal auditing functions in South Africa. Compliance with the internal auditing standards (implemented on 1 January 2002) should contribute to improve the situation. The internal auditors’ professional body should motivate internal auditing functions to exercise quality control according to the internal auditing standards. This will uplift the image of the internal auditing profession and ensure the future existence of internal auditing functions. / Auditing / M.Comm.
36

Gehaltebeheer binne interne ouditfunksies en die toepassing daarvan in Suid-Afrika

Marais, Marinda 30 June 2003 (has links)
The purpose of quality control within internal auditing functions is to ensure that internal auditing functions add value by providing a quality service. The aim of this research project was to investigate the importance of quality control within internal auditing functions as prescribed by the standards and guidelines of the internal auditing profession. It was also attempted to determine to what extent these standards and guidelines are applied within internal auditing functions in South Africa. The study concluded that quality control is not adequately applied within all internal auditing functions in South Africa. Compliance with the internal auditing standards (implemented on 1 January 2002) should contribute to improve the situation. The internal auditors’ professional body should motivate internal auditing functions to exercise quality control according to the internal auditing standards. This will uplift the image of the internal auditing profession and ensure the future existence of internal auditing functions. / Auditing / M.Comm.
37

SSIM-Inspired Quality Assessment, Compression, and Processing for Visual Communications

Rehman, Abdul January 2013 (has links)
Objective Image and Video Quality Assessment (I/VQA) measures predict image/video quality as perceived by human beings - the ultimate consumers of visual data. Existing research in the area is mainly limited to benchmarking and monitoring of visual data. The use of I/VQA measures in the design and optimization of image/video processing algorithms and systems is more desirable, challenging and fruitful but has not been well explored. Among the recently proposed objective I/VQA approaches, the structural similarity (SSIM) index and its variants have emerged as promising measures that show superior performance as compared to the widely used mean squared error (MSE) and are computationally simple compared with other state-of-the-art perceptual quality measures. In addition, SSIM has a number of desirable mathematical properties for optimization tasks. The goal of this research is to break the tradition of using MSE as the optimization criterion for image and video processing algorithms. We tackle several important problems in visual communication applications by exploiting SSIM-inspired design and optimization to achieve significantly better performance. Firstly, the original SSIM is a Full-Reference IQA (FR-IQA) measure that requires access to the original reference image, making it impractical in many visual communication applications. We propose a general purpose Reduced-Reference IQA (RR-IQA) method that can estimate SSIM with high accuracy with the help of a small number of RR features extracted from the original image. Furthermore, we introduce and demonstrate the novel idea of partially repairing an image using RR features. Secondly, image processing algorithms such as image de-noising and image super-resolution are required at various stages of visual communication systems, starting from image acquisition to image display at the receiver. We incorporate SSIM into the framework of sparse signal representation and non-local means methods and demonstrate improved performance in image de-noising and super-resolution. Thirdly, we incorporate SSIM into the framework of perceptual video compression. We propose an SSIM-based rate-distortion optimization scheme and an SSIM-inspired divisive optimization method that transforms the DCT domain frame residuals to a perceptually uniform space. Both approaches demonstrate the potential to largely improve the rate-distortion performance of state-of-the-art video codecs. Finally, in real-world visual communications, it is a common experience that end-users receive video with significantly time-varying quality due to the variations in video content/complexity, codec configuration, and network conditions. How human visual quality of experience (QoE) changes with such time-varying video quality is not yet well-understood. We propose a quality adaptation model that is asymmetrically tuned to increasing and decreasing quality. The model improves upon the direct SSIM approach in predicting subjective perceptual experience of time-varying video quality.
38

SSIM-Inspired Quality Assessment, Compression, and Processing for Visual Communications

Rehman, Abdul January 2013 (has links)
Objective Image and Video Quality Assessment (I/VQA) measures predict image/video quality as perceived by human beings - the ultimate consumers of visual data. Existing research in the area is mainly limited to benchmarking and monitoring of visual data. The use of I/VQA measures in the design and optimization of image/video processing algorithms and systems is more desirable, challenging and fruitful but has not been well explored. Among the recently proposed objective I/VQA approaches, the structural similarity (SSIM) index and its variants have emerged as promising measures that show superior performance as compared to the widely used mean squared error (MSE) and are computationally simple compared with other state-of-the-art perceptual quality measures. In addition, SSIM has a number of desirable mathematical properties for optimization tasks. The goal of this research is to break the tradition of using MSE as the optimization criterion for image and video processing algorithms. We tackle several important problems in visual communication applications by exploiting SSIM-inspired design and optimization to achieve significantly better performance. Firstly, the original SSIM is a Full-Reference IQA (FR-IQA) measure that requires access to the original reference image, making it impractical in many visual communication applications. We propose a general purpose Reduced-Reference IQA (RR-IQA) method that can estimate SSIM with high accuracy with the help of a small number of RR features extracted from the original image. Furthermore, we introduce and demonstrate the novel idea of partially repairing an image using RR features. Secondly, image processing algorithms such as image de-noising and image super-resolution are required at various stages of visual communication systems, starting from image acquisition to image display at the receiver. We incorporate SSIM into the framework of sparse signal representation and non-local means methods and demonstrate improved performance in image de-noising and super-resolution. Thirdly, we incorporate SSIM into the framework of perceptual video compression. We propose an SSIM-based rate-distortion optimization scheme and an SSIM-inspired divisive optimization method that transforms the DCT domain frame residuals to a perceptually uniform space. Both approaches demonstrate the potential to largely improve the rate-distortion performance of state-of-the-art video codecs. Finally, in real-world visual communications, it is a common experience that end-users receive video with significantly time-varying quality due to the variations in video content/complexity, codec configuration, and network conditions. How human visual quality of experience (QoE) changes with such time-varying video quality is not yet well-understood. We propose a quality adaptation model that is asymmetrically tuned to increasing and decreasing quality. The model improves upon the direct SSIM approach in predicting subjective perceptual experience of time-varying video quality.
39

Hodnocení kvality vybraného komoditního produktu / Quality assessment of the selected commodity product

Syrovátková, Irena January 2008 (has links)
The quality of a product is very important nowadays. The customer take into account by the purchase of the product not only price and the quantity of the purchased product but also he requires mainly its quality. The theme of the disertation is the comparison of selected motorcycles of the same category and different brands which are sold in the Czech market. Here is mentioned the basic information about their engineering characteristic, costs, design and customer service. On the basis of these charakteristics was analyzed the quality of motorcycles in the each group of evaluation. After that was determined the average sequence accordance with particular issues. Questionnaire was created to the quality of the motorcycles was set objectively. Its elaboration helped to better evaluation of the motorcycles and to find out which characteristics of are consider to cover up into the evaluation.
40

Through the eye of a student : customer care in academic libraries, a case at the Central University of Technology, Free State

Molopyane, J January 2013 (has links)
Published Article / The purpose of this research was to investigate the perceptions of clients namely, students, about the quality of library services and also the quality of staff client relationship. It was envisaged that through this study the perceptions, feelings and views of students in as far as their needs satisfaction could be illuminated. The study addressed the following concerns: Apart from the physical and other library resources, are there other mechanisms of evaluating the quality of services an academic library has to offer? In order for an academic library to improve service quality, what role should clients play? What are their concerns about their information needs consideration and what other possible means can be done to satisfy those needs?

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