891 |
Engineering Complex Systems with an Emphasis on Robustness: Utility-Based Analysis with Focus on RobustnessBaxter, Benjamin Andrew 16 December 2013 (has links)
Engineered system complexity continues to increase rapidly, concurrent with the requirement for the engineered system to be robust. Robustness is often considered a critical attribute of complex engineered systems, but an exact definition of robustness is not agreed upon within the systems engineering community. Lack of a clear definition, makes it difficult to develop or utilize a quantitative measure of robustness. Having a formal measure for robustness may not be considered necessary, but a lack of a specific measure results in the inability to communicate the desired level of robustness, inability to measure how various options impact robustness, and makes it difficult to measure tradeoffs between robustness and other engineering parameters.
The objective of this research is to examine robustness and how it can be attained in systems engineering. In order to accomplish this objective, data from several scientific communities is examined to develop the meaning of robustness. While definitions between and even within each community differ, a key attribute is present in each definition: A robust system needs to maintain its core functions in the presence of internal and external changes. The key component of the characteristic is that each function within a system has its own measure of robustness.
When robustness and engineering are discussed, Robust Design must be examined. The scientific community uses variance as its measure for robustness. The Robust Design method has the adverse characteristic of forcing preferences upon the designer. Examining the mean-variance approach with utility theory shows that it imposes an increasingly risk averse position upon the designer. This position may not be compatible with the designer’s true risk attitude, causing issues when applying the method.
To contend with this issue, a novel utility-based approach is suggested. The approach focuses on generating functional models of the proposed systems, which provide the designer with insight into which perturbations are relevant to the system and subsystems. Additionally this approach incorporates utility theory to allow the designer to convey their preferences. The utility-based approach allows the designer to convey their own preferences, while incorporating steps to ensure the final design is robust.
|
892 |
Viability of Photogrammetry for As-built Surveys without Control Points in Building Renovation ProjectsLiu, Yang 16 December 2013 (has links)
In recent years, it is becoming more and more common to utilize 3D modeling technology to reconstruct cultural heritages. The most common way to deliver the 3D model of an existing object is based on hands-on surveys and CAD tools which could be impractical for large or complex structure in term of time consumption and cost. Recently, laser scanning technology and more automated photogrammetric modeling methods become available, and making the 3D reconstruction process of real world objects easier. Photogrammetry is one of the most cost-effective approaches we could use to gather the physical information of an object, such as size, location, and appearance. Also, the operation of the equipment of photogrammetry, which is a camera, is very easy and cost-effective. However, it also has its drawback, which is mainly caused the outcome’s low accuracy level. Accurate drawings or models only have been achieved with other approaches, such as 3D laser scanning or total station.
The 3D model of the Francis Hall at Texas A&M University, which will be renovated soon, was created in order to investigate whether the image-based 3D model produced using photogrammetry technology would be acceptable or not for the use in renovation projects. For this investigation, the elapsed time for data acquisition and 3D modeling was measured. The accuracy level of the image-based 3D model and the deficiencies of this approach were also recorded. Then, the image-based 3D model of Francis Hall was presented in the BIM CAVE to four industry professionals and one graduate student. The regular 3D model of the Francis Hall, which was created, using dimensions extracted from 2D drawings, was also presented to the interviewees in the BIM CAVE. After watching two different 3D models (image-based 3D model and regular 3D model) of the same Francis Hall, five interviewees were requested to describe the differences they noticed between image-based 3D model and regular 3D model presented in the BIM CAVE.
By reviewing and analyzing the data from interviews. Following conclusions could be made. First, the image-based 3D model of Francis Hall gave people more feeling of reality than the traditional CAD drawings or BIM models. Second, the image-based 3D model could be used for saving travels, showing details, improving coordination, improving design, facilities management tool, and marketing tool. Third, in order to make it practical for the industry, the time consumption and cost of generating the image-based 3D model should be at least equivalent to time consumption and cost for architects to conduct survey and generate CAD drawings or BIM model.
|
893 |
Development and Automatic Monitoring of Trust-Aware Service-Based SoftwareUddin, Mohammad Gias 12 February 2008 (has links)
Service-based software can be exploited by potentially untrustworthy service requestors while providing services. Given that, it is
important to identify, analyze the trust relationships between service providers and requestors, and incorporate them into the
service-based software. Treating trust as a nonfunctional requirement (NFR) during software development and monitoring allows
clarifying these relationships and measuring the trustworthiness of service requestors. This analysis is facilitated by incorporating
trust scenarios and trust models into the software. A trust scenario describes a trust relationship between interested parties based on a specific context. A trust model provides trust equations to measure the trustworthiness of service requestors based on the analysis of service-based interactions. Although much research has been devoted to monitor service quality, to date, no approach has been proposed
to develop and automatically monitor service providing software from trust perspectives.
In this thesis, we propose a trust-aware service-based software development framework which utilizes our proposed Unified Modeling
Language (UML) extension called UMLtrust (UML for trust scenarios)to specify the trust scenarios of a service provider and
incorporates our developed trust model called CAT (Context-Aware Trust) into the software to calculate the trustworthiness of service
requestors. The trust scenarios are converted to trust rules to monitor service-based interactions. A service requestor is penalized for the violation of a trust rule and rewarded when no rule is violated. The trustworthiness of the requestor is then calculated (using the equations of CAT) based on the current request, outcomes of previous requests, and recommendations from other service providers. A trust-based service granting algorithm is presented to decide whether a service requestor should be granted the requested service. A trust monitoring architecture is presented which is
assumed to reside in each service provider. The monitor uses trust rules from UMLtrust specifications and trust equations from CAT to analyze service-based interactions. The incorporation of the monitor into a provider makes it trust-aware. A trust monitoring algorithm is provided to analyze interactions and make decisions at run-time. A prototype of a file sharing service-based grid is implemented to evaluate the applicability of our framework that confirms the effectiveness of the framework. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2008-02-11 15:57:22.003 / Natural Sciences and Engineering Research Council (NSERC)
|
894 |
An investigation into the pathophysiology of non-specific arm pain: an examination of the utility and reliability of quantitative electomyographyCalder, KRISTINA 18 November 2009 (has links)
The wrist extensor muscles have been implicated in a work-related upper limb disorder referred to as non-specific arm pain (NSAP), which has an unknown pathophysiology. The primary objective of this thesis was to perform an electrophysiological evaluation of NSAP to gain a better understanding of the underlying pathophysiology. Secondary objectives were to determine the utility and reliability of the decomposition-based quantitative electromyography (DQEMG) system used to examine NSAP.
The utility of the DQEMG system was first tested to determine whether physiological changes in muscles of healthy individuals performing low-level fatiguing contractions could be detected using this approach. Next, the reliability of the outcome variables produced through this system was tested on healthy individuals performing low-level non-fatiguing contractions. A case-control study was then performed using DQEMG to determine whether there were measurable changes in electrophysiological variables that suggest whether NSAP is myopathic or neuropathic in nature. Finally, the case control study was repeated using a less invasive approach of electrophysiological evaluation to determine if this method might be equally useful in determining the pathophysiology of NSAP.
Results revealed DQEMG can be effectively and reliably used to detect changes in the physiological characteristics of motor units that accompany fatigue. Specifically, decreases in mean motor unit firing rates along with increases in amplitude, duration, and area parameters of needle- and surface-detected motor unit potentials (MUPs) suggest that recruitment is a main cause of increased electromyographic amplitude parameters with fatigue. Results of the reliability study suggested that DQEMG provides sufficiently consistent results to allow it to be effectively used for quantitative electromyographic (QEMG) analysis. In the first case control study, the QEMG parameters suggested that the underlying pathophysiology in NSAP may be myopathic in nature; specifically, QEMG findings for the NSAP group revealed smaller MUPs compared to the other groups. Lastly, the case control study using spike shape analysis across different levels of isometric wrist extension contractions was deemed to be useful in determining differences among the groups. This research suggests that NSAP may be myopathic in nature, since the NSAP group showed significantly lower mean spike amplitude and mean spike slope values compared to healthy subjects. / Thesis (Ph.D, Rehabilitation Science) -- Queen's University, 2008-08-27 14:53:55.892
|
895 |
Educational Innovation in an Undergraduate Medical Course: Implementation of a Blended e-Learning, Team-Based Learning ModelDavidson, Lindsay 26 January 2009 (has links)
Medical education has been the subject of ongoing reform since the second part of the 18th century (Papa & Harasym, 1999). Most recently, medical education has been redefined to include a broad set of competencies over and above traditional expertise. In an attempt to facilitate this approach, different instructional models have been proposed. Most of these seek to foster learner engagement and active participation and promote life-long learning. Nevertheless, there is no consensus amongst medical educators about the optimal way to teach future physicians.
Despite the efforts of both researchers and local champions, instructional innovations frequently fail. Fullan (2001) ascribes this to faulty assumptions on the part of planners as well as to the inherent complexity of the organizations involved, further stating that effective change requires some degree of reculturing. This study examines the process of educational change in an undergraduate medical course over a three-year period. Formerly taught exclusively by large class lectures, the course was redesigned to include a blend of e-learning and Team-Based Learning (TBL). The process of change is described and viewed in parallel from the perspectives of both student and teacher while uncovering contextual and process elements that contributed to the outcome.
Shifting student attitudes to teaching and learning were identified over time, suggesting that these evolve in parallel to faculty experience implementing a new teaching strategy. Van Melle (2005) has suggested that acceptance of educational innovation is dependent on the environment and organizational context. The results of this study highlight the importance of these factors in the successful introduction of a new instructional paradigm as well as the value of longitudinal evaluation of instructional changes in order to better understand their transformational potential. / Thesis (Master, Education) -- Queen's University, 2009-01-24 10:02:24.877
|
896 |
Feature Based Registration of Ultrasound and CT Data of a ScaphoidKoslowski, Brian 28 May 2010 (has links)
Computer assisted surgery uses a collection of different techniques including but not limited to: CT-guided, fluoroscopy-guided, and ultrasound-guided imaging which allows medical staff to view bony anatomy of a patient in relation to surgical tools on a computer screen. By providing this visual data to surgeons less invasive surgeries can be performed on a patient's fractured scaphoid. The data required for a surgeon to perform a minimally invasive surgery while looking only at a computer screen, and not directly at a patient's anatomy, will be provided by CT and ultrasound data. We will discuss how ultrasound and CT data can be used together to allow a minimally invasive surgery of the scaphoid to be performed.
In this thesis we will explore two techniques of registering segmented ultrasound images to CT data; an Iterative Closest Point (ICP) approach, and an Unscented Kalman Filter-based Registration (UKF). We use two different ultrasound segmentation methods; a semi-automatic segmentation, and a Bayesian segmentation technique. The segmented ultrasound data is then registered to a CT volume. The success or failure of the
registrations is measured by the error calculated in mapping the corresponding land-
marks to one another and calculating the target registration error. The results show that the Unscented Kalman Filter-based registration using the Bayesian segmentation of ultrasound images has the least registration error, and has the most robustness to error in initial alignment of the two data sets. / Thesis (Master, Computing) -- Queen's University, 2010-05-28 11:17:31.934
|
897 |
Assessing the potential to involve healers in expanding coverage of cARV programs in rural western UgandaHuntington, Janis Dawn Unknown Date
No description available.
|
898 |
An ontology-driven concept-based information retrieval approach for web documentsLi, Zhan Unknown Date
No description available.
|
899 |
Picture this: evaluating a nonprofit arts-based children's program through photographyKisilevich, Susan Joan Unknown Date
No description available.
|
900 |
A cognitive approach to multi-verb constructions in Mandarin ChineseYin, Hui Unknown Date
No description available.
|
Page generated in 0.0618 seconds