M.Sc. (Informatics) / Please refer to full text to view abstract

A 3D visualization tool for file system hierarchies is presented. The visualization technique used is based on the Tree-map / nested Venn diagram concept and is capable of visualizing metrics and attributes such as size, change and file type for thousands of nodes simultaneously. Size is visualized through node base area, change is visualized through the ghosting and hiding of unchanged nodes and file type is visualized through colors. Actions such as navigation and selection are performed exclusively in 3D. Finally a method for improving the visibility of nodes through the equalization of sibling nodes is proposed. / Ett 3D visualiseringsverktyg för filsystem presenteras. Visualiseringstekniken är baserad på Tree-maps / Venn diagram och kan visualisera attribut såsom storlek, förändring och filtyp för tusentals noder samtidigt. Storlek visualiseras genom noders bas area, förändringar visualiseras genom ghosting (avfokusering) och hiding (gömning) av oförändrade noder och filtyp visualiseras med färger. Slutligen så föreslås en metod för att förbättra synligheten hos noder genom utjämning. / Tel. 0457-26310 Alt. 044-246025 (annars e-mail)

Storage devices based on Multi-Level Cell (MLC) NAND flash can be found in almost all computer systems except rugged, industrial systems; even though MLC is less expensive and more dense than devices based on standard Single-Level Cell (SLC) NAND flash, MLC’s lower write endurance and lower retention has led system designers to avoid using it. This avoidance is unnecessary in many applications which will never come close to the endurance limits. Furthermore, new processes are leading to storage devices with higher write endurance. System designers should review the specific use-model for their systems and can select MLC-based storage devices when warranted. The result is lower system costs without worry of data loss due to write endurance.

Increased production and use of multimedia data has led to the development of a more advanced Database Management System (DBMS), like an Object Relational Database Management System (ORDBMS). These advanced databases are necessitated by the complexity in structure and the functionality required by multimedia data. Unfortunately, no suitable benchmarks exist with which to test the performance of databases when handling multimedia data. This thesis describes the design of a benchmark to measure the performance of basic functionality found in multimedia databases. The benchmark, called MORD (Multimedia Object Relational Databases), targets Oracle, a well known commercial Object Relational Database Management System (ORDBMS) that can handle multimedia data. Although MORD targets Oracle, it can easily be applied to other Multimedia Database Management System (MMDBMS) as a result of a design that stressed its portability, and simplicity. MORD consists of a database schema, test data, and code to simulate representative queries on multimedia databases. A number of experiments are described that validate MORD and ensure its correct design and that its objectives are met. A by-product of these experiments is an initial understanding of the performance of multimedia databases. The experiments show that with multimedia data the buffer cache should be at least large enough to hold the largest dataset, a bigger block size improves the performance, and turning off logging and caching for bulk loading improves the performance. MORD can be used to compare different ORDBMS or to assist in the configuration of a specific database.

To explore the feasibility of processing Compact Muon Solenoid (CMS) analysis jobs across the wide area network, the FIU CMS Tier-3 center and the Florida CMS Tier-2 center designed a remote data access strategy. A Kerberized Lustre test bed was installed at the Tier-2 with the design to provide storage resources to private-facing worker nodes at the Tier-3. However, the Kerberos security layer is not capable of authenticating resources behind a private network. As a remedy, an xrootd server on a public-facing node at the Tier-3 was installed to export the file system to the private-facing worker nodes. We report the performance of CMS analysis jobs processed by the Tier-3 worker nodes accessing data from a Kerberized Lustre file. The processing performance of this configuration is benchmarked against a direct connection to the Lustre file system, and separately, where the xrootd server is near the Lustre file system.

No description available.

Objective: This study evaluated the reliability of the digits-in-noise (DIN) test application across various low and high-end digital devices utilizing different transducers and sound file types. Design: The study utilized a cross-sectional within-subject design. Methods: The study consisted of two objectives. In the first objective, 40 normal hearing participants aged between 18 to 24 years (mean: 20; SD= 1.9) were recruited. Speech Reception Thresholds (SRTs) across Android smartphones (one low-end and one high-end smartphone), as well as an Android tablet coupled with different transducers (headphones and earphones) were compared. For the second objective, participants comprised of 12 normal-hearing females aged between 23 to 24 years (mean: 23, SD= 0.5). SRTs were compared across three different sound file types (OGG file, AAC file and MP3 file). Results: There was no significant difference in the SRTs between electronic devices or transducers used (p< 0.05). Furthermore, between the different sound files used, the difference was also not significant (p< 0.05). Conclusions: The DIN test is reliable when conducted across different electronic devices, regardless of the transducer or sound file type used. Therefore, the DIN test is clinically valid when downloaded and performed on Android devices despite the cost of the device thus offering greater usability in a variety of audiological contexts. / Dissertation (MA)--University of Pretoria, 2019. / Speech-Language Pathology and Audiology / MA / Unrestricted

This master’s thesis deals with the topic of program source code compilation for RISC-V processor architecture. The generated object files need to be compatible with GNU binutils open source tools which are already available for the architecture. The focus is on relocations which must be correctly detected in Codasip Studio tools and transformed into RISC-V platform specific relocation types.

The topic of this masterâs thesis is the development of a file generator which will be used as a support tool for web application development in LOGEX Solution Center s.r.o. The application was written in TypeScript using the Node.js JavaScript runtime.

<div>Cloud and parallel computing are fundamental components in the processing of large data sets. Deployments of distributed computers require network infrastructure that is fast, efficient, and secure. Software Defined Networking (SDN) separates the forwarding of network data by switches (data plane) from the setting and managing of network policies (control plane). While this separation provides flexibility for setting network policies affecting the establishment of network flows in the data plane, it provides little to no fault tolerance for failures, either benign or caused by corrupted/malicious applications. Such failures can cause network flows to be incorrectly routed through the network or stop such flows altogether. Without protection against faults, cloud network providers using SDN run the risk of inefficient allocation of network resources or even data loss. Furthermore, the asynchronous nature existing protocols for SDN does not provide a mechanism for consistency in network policy updates across multiple switches.</div><div>In addition, cloud and parallel applications require an efficient means for accessing local system data (input data sets, temporary storage locations, etc.). While in many cases it may be possible for a process to access this data by making calls directly to a file system (FS) kernel driver, this is not always possible (e.g. when using experimental distributed FSs where the needed libraries for accessing the FS only exist in user space).</div><div>This dissertation provides a design for fault tolerance of SDN and infrastructure for advancing the performance of user space FSs. It is divided into three main parts. The first part describes a fault tolerant, distributed SDN control plane framework. The second part expands upon the fault tolerant approach to SDN control plane by providing a practical means for dynamic control plane membership as well as providing a simple mechanism for controller authentication through threshold signatures. The third part describes an efficient framework for user space FS access.</div><div>This research makes three contributions. First, the design, specification, implementation, and evaluation of a method for fault tolerant SDN control plane that is inter-operable with existing control plane applications involving minimal instrumentation of the data plane runtime. Second, the design, specification, implementation and evaluation of a mechanism for dynamic SDN control plane membership that all ensure consistency of network policy updates and minimizes switch overhead through the use of distributed key generation and threshold signatures. Third, the design, specification, implementation, and evaluation of a user space FS access framework that is correct to the Portable Operating System Interface (POSIX) specification with significantly better performance over existing user space access methods, while requiring no implementation changes for application programmers.</div>