64 research outputs found
The Remains of authoritarianism : bureaucracy and civil society in post-authoritarian Greece
No full textDimitrios A. Sotiropoulos. 30 cm. He presented this paper at a seminar held at the Center on October 21, 1994. - T.p. Includes bibliographical references (p. 31-35
ATHENS City of Crossroads
No full textThe project investigates the possibility of an alternative movement pattern in the City of Athens. The crossroad condition is the one that demonstrates the new urban logic through three different case study. The movement takes the form of a multilevel labyrinth that penetrates the urban mass and forms a new collective space.Expolore LabArchitectureArchitecture and The Built Environmen
Corpus Callosum as a biomarker for Alzheimer and Multiple Sclerosis
No full textWith the increase of the life expectancy and the deterioration of the quality of life that neurodegenerative diseases can cause to the patients, they have been receiving more and more attention the last few decades in the developed countries. Two of the leading neurodegenerative diseases are Alzheimer’s Disease and Multiple Sclerosis. In diagnosis and assessment progression Magnetic Resonance Imaging (MRI) is playing an important role. MRI is a non-invasive tool and can achieve a great contrast between the different tissues that exist inside the brain. In the search of biomarkers for the faster diagnosis of these diseases, the Corpus Callosum appears to be an interesting brain structure, as it facilitates inter-hemispheric communication and it is not sensitive to brain hydration and dehydration effects. This thesis investigates if the regional and global shape and area changes of the Cor- pus Callosum could set the Corpus Callosum as a biomarker for Alzheimer’s Disease and Multiple Sclerosis. In order to achieve that a segmentation pipeline is proposed, so as to extract the Corpus Callosum from Magnetic Resonance brain images. After such a pipeline is constructed and validated, the quantification of the Corpus Callosum area is investigated for scans acquired in scanners of different vendors and in scanners of different magnetic field strengths, in order to gain better insights of the differences that can exist between such scans. Finally, the potential of the Corpus Callosum to be used as a biomarker is investigated, by attempting to correlate the global and regional shape and area changes of the Corpus Callosum with neurodegenerative diseases. During the thesis the segmentation algorithm showed a high segmentation accuracy performance with a mean dice of 93%, a segmentation reproducibility error of 1.93% and the clas- sification accuracy between AD and MS patients with NC was above 95% for both groups.BMEBioMechanical EngineeringMechanical, Maritime and Materials Engineerin
Integrated entangling gates: Creating GHZ States for Stabilizer Measurements in Distributed Quantum Computing
No full textHigh fidelity GHZ states among remote nodes is a precious commodity which can allow for non-local stabilizer measurements and thus pave the way for a modular fault-tolerant quantum computer. To this end, we extend the high fidelity intracavity gate introduced by Borregaard et al. (2015) to distributed paradigm, consisting of SnV-inspired atomic states in cavities connected by fibers. The adiabatic dynamics of this system can be solved efficiently using the effective operator formalism of Reiter and Sørensen (2012). We develop a Python framework that enables the analytical calculation of these effective dynamics reliably and swiftly, while being versatile and easily modifiable. The possibilities of this framework are showcased by obtaining results for a symmetric distributed setup and verifying its scalability. We present the ways that it can be optimized while taking into consideration experimentally inspired constraints, and proceed to optimize it for GHZ generation in color centers. These optimized gates are compared against an emission based protocol using the GHZ creation simulations of the Modicum protocol. As a byproduct of our investigation, we identify a specific set of Hamiltonians which, under certain conditions, can generate GHZ states with a single multi-qubit entangling gate.Applied Physics | Quantum Technolog
Subcontracting in public employment services: the design and delivery of ‘outcome based’ and ‘black box’ contracts: analytical paper
No full textA Study of Bugs Found in the Moby Configuration Management System
No full textThe study of bugs can provide important information to understand their nature in the context of complex software systems as well as supporting developers in their detection, fix and prevention. Previous studies focused on analyzing bugs under different perspectives such as changes at code level, frequency, semantics, symptoms, root causes and reproducibility through test cases. Although these studies offer valid methodologies that can be applied in different areas of bugs analysis, literature suggests that very little focus has been aimed towards configuration management systems.This research has the goal to provide a characterization of bugs in the Moby configuration management system, an open framework used to create container systems. A random sample of 100 collected Moby bugs is manually inspected and categorized by their (1) symptoms, (2) root causes, (3) impact, (4) fixes, (5) system dependency and (6) triggers. Some representative takeaways suggest that: bugs symptoms are mostly linked to a specific root cause, which means that bugs occur in certain areas of the system; the modular nature of Moby drives up the criticality of the bugs as each component needs to work correctly; bugs are overall hard to reproduce as only 24.5\% of the fixes included a test case; developing an automatic tool that provides a historical distribution of bugs can support maintainers in their work by enhancing bugs prevention.The research provides an analysis and categorization of bugs in the Moby configuration management system. The work adds a new perspective to the literature on the topics of both bugs analysis and configuration management systems and can be used as a starting point for further studies.https://github.com/MKrupauskas/tudelft-research Open source repository with the script used to obtain the results discussed in the paper.CSE3000 Research ProjectComputer Science and Engineerin
Finding typing compiler bugs
No full textWe propose a testing framework for validating static typing procedures in compilers. Our core component is a program generator suitably crafted for producing programs that are likely to trigger typing compiler bugs. One of our main contributions is that our program generator gives rise to transformation-based compiler testing for finding typing bugs. We present two novel approaches (type erasure mutation and type overwriting mutation) that apply targeted transformations to an input program to reveal type inference and soundness compiler bugs respectively. Both approaches are guided by an intra-procedural type inference analysis used to capture type information flow. We implement our techniques as a tool, which we call Hephaestus. The extensibility of Hephaestus enables us to test the compilers of three popular JVM languages: Java, Kotlin, and Groovy. Within nine months of testing, we have found 156 bugs (137 confirmed and 85 fixed) with diverse manifestations and root causes in all the examined compilers. Most of the discovered bugs lie in the heart of many critical components related to static typing, such as type inference.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Software Engineerin
Studying bugs in the Salt Configuration Management System
No full textConfiguration management systems are a class of software used to automate system administrative tasks, one of which is the configuration of software systems. Although the automation is less error-prone than manual configuration done by a human, bugs in the source code can still cause configuration errors. This can result into unwanted consequences for the managed software system, some examples are performance degradation, downtime and security breaches.Bug studies are conducted on previously reported bugs to find out their characteristics. Such findings help with preventing, detecting and fixing bugs, which ultimately causes software to become more reliable. This paper aims to fill in a research gap in the literature surrounding bug studies conducted on configuration management systems. From Salt, a widely used open-source configuration management system, a data-set of 5,896 bugs with fixes was collected. The main research question answered by this paper is ``What are the common patterns can be extracted from bugs found in Salt?'' To answer this, 100 bugs were randomly sampled from this data-set to analyze their symptoms, root causes, impact, fixes, system-dependence and triggers.CSE3000 Research ProjectComputer Science and Engineerin
A study of bugs found in the Ansible configuration management system
No full textResearch that focuses on examining software bugs is critical when developing tools for preventing and for fixing software issues. Previous work in this area has explored other types of systems, such as bugs of compilers and security issues stemming from open source systems hosted on public repositories. This paper explores the bugs within the Ansible software provisioning and configuration management system. The main question this paper seeks to answer is "What common patterns can be extracted from the bugs found and what are the root causes, symptoms, triggers, system-dependence factors, fixes, and the impact of the most frequent types of bugs in the Ansible configuration management system". This study defines a data pipeline and custom tools to extract and analyze 100 Ansible bugs. Common classifications are determined, and the bugs are manually classified, revealing common patters within the bugs. Insights are drawn from the aggregated data, and recommendations are made for addressing bug-prone areas of execution and connectivity components, and expanding the test suite with input fuzzing and a genetic algorithms test solution, in order to improve the overall code quality of the Ansible code base.CSE3000 Research ProjectComputer Science and Engineerin
A Study of Bugs Found in the Puppet Configuration Management System
No full textThis research studies the symptoms, root causes, impact, triggers, fixes, and system dependency of bugs in the Puppet configuration management system. Puppet is a widely used open-source configuration management system that performs various administrative tasks on machines based on a central specification. This paper aims to fill the research gap and help improve the understanding of these systems. 2146 registered bugs and fixes are collected and a random sample of 100 is analyzed to answer the research questions. The most common bug types have the symptom of unexpected runtime behavior. The root cause is generally incorrect target machine operations. The impact severity is typically medium and the impact consequence of most bugs is target configuration failure. Bug fixes tend to be small method code changes and usually occur in the execution component. Bugs are generally system-independent and are caused by logic errors that can be triggered by specifically executing an erroneous module. The analysis shows that applying automated bug discovery methods to the most error-prone execution and parser components of the system would lead to the largest improvement in the system’s quality.CSE3000 Research ProjectComputer Science and Engineerin
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