Apples datorer med operativsystemet OS X blir allt vanligare på arbetsplatserna. För att företagets IT-avdelning ska kunna upprätthålla en stabil och säker miljö strävar man efter att standardisera system och hårdvara. Verkligheten stämmer inte alltid överens med IT-avdelningens strävan och anställda vill i ökande grad använda sig av produkter de valt själva. Arbetet har undersökt möjligheterna och begränsningarna med att integrera Apple OS X i Microsofts Active Directory. För att kunna besvara de frågor som använts som avgränsning inleddes arbetet med att metodiskt studera litteratur och på internet publicerade artiklar. Därefter har laborationer med och utan tredjepartsmjukvarorna ADmitMac och Centrify genomförts med inriktning på arbetets avgränsningar. Parallellt med detta har intervjuer av organisationer med olika bakgrund genomförts. Intervjuer och laborationer gav ett resultat som sedan diskuterades i rapportens avslutande del. I analysen gjordes en jämförelse av resultaten från intervjuer samt laborationer. Från detta kunde bland annat följande slutsats dras; För att integrera en dator med Apple OS X i Active Directory fungerar det inbyggda stödet men med begränsad funktionalitet. Med hjälp av tredjepartsmjukvaror utökas stödet och fler funktioner i Active Directory kan användas.

The concept of wireless sensor network (WSN) is where tiny devices (sensor nodes), positioned fairly close to each other, are used for sensing and gathering data from its environment and exchange information through wireless connections between these nodes (e.g. sensor nodes distributed through out a bridge for monitoring the mechanical stress level of the bridge continuously). In order to easily deploy a relatively large quantity of sensor nodes, the sensor nodes are typically designed for low price and small size, thereby causing them to have very limited resources available (e.g. energy, processing power). Over the years, different security (cryptographic) primitives have been proposed and refined aiming at utilizing modern processor’s power e.g. 32-bit or 64-bit operation, architecture such as MMX (Multi Media Extension) and etc. In other words, security primitives have targeted at high-end systems (e.g. desktop or server) in software implementations. Some hardware-oriented security primitives have also been proposed. However, most of them have been designed aiming only at large message and high speed hashing, with no power consumption or other resources (such as memory space) taken into considerations. As a result, security mechanisms for ultra-low power (<500µW) devices such as the wireless sensor nodes must be carefully selected or designed with their limited resources in mind. The objective of this project is to provide implementations of security primitives (i.e. encryption and authentication) suitable to the WSN environment, where resources are extremely limited. The goal of the project is to provide an efficient building block on which the design of WSN secure routing protocols can be based on, so it can relieve the protocol designers from having to design everything from scratch. This project has provided three main contributions to the WSN field.  Provides analysis of different tradeoffs between cryptographic security strength and performances, which then provide security primitives suitable for the needs in a WSN environment. Security primitives form the link layer security and act as building blocks for higher layer protocols i.e. secure routing protocol.  Implements and optimizes several security primitives in a low-power microcontroller (TI MSP430F1232) with very limited resources (256 bytes RAM, 8KB flash program memory). The different security primitives are compared according to the number of CPU cycles required per byte processed, specific architectures required (e.g. multiplier, large bit shift) and resources (RAM, ROM/flash) required. These comparisons assist in the evaluation of its corresponding energy consumption, and thus the applicability to wireless sensor nodes.  Apart from investigating security primitives, research on various security protocols designed for WSN have also been conducted in order to optimize the security primitives for the security protocols design trend. Further, a new link layer security protocol using optimized security primitives is also proposed. This new protocol shows an improvement over the existing link layer security protocols. Security primitives with confidentiality and authenticity functions are implemented in the TinyMote sensor nodes from the Technical University of Vienna in a wireless sensor network. This is to demonstrate the practicality of the designs of this thesis in a real-world WSN environment. This research has achieved ultra-low power security primitives in wireless sensor network with average power consumption less than 3.5 µW (at 2 second packet transmission interval) and 700 nW (at 5 second packet transmission interval). The proposed link layer security protocol has also shown improvements over existing protocols in both security and power consumption. / Dissertation (MEng (Computer Engineering))--University of Pretoria, 2008. / Electrical, Electronic and Computer Engineering / unrestricted

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Communication underwater is challenging because of the inherent characteristics of the media. First, common radio frequency (RF) signals utilized in wireless communications cannot be used under water. RF signals are attenuated in such as way that RF communication underwater is restricted to very few meters. As a result, acoustic-based communication is utilized for underwater communications; however, acoustic communication has its own limitations. For example, the speed of sound is five orders of magnitude lower than the speed of light, meaning that communications under water experience long propagation delays, even in short distances. Long propagation delays impose strong challenges in the design of Data Link Layer (DLL) protocols. The underwater communication channel is noisy, too. The bit error rate (BER) can also change depending on depth and other factors, and the errors are correlated, like in wireless communications. As in wireless communications, transducers for acoustic communication are half duplex, limiting the application of well-known detection mechanisms in Medium Access Control (MAC) layer protocols. Further, known problems like the hidden and exposed terminal problem also occur here. All these aspects together make the underwater communication channel to have the worst characteristics of all other known channels. Because of these reasons, underwater scenarios are complicated to implement, especially when they have underwater autonomous vehicles exchanging information among them. This dissertation proposes data link layer protocols in support of swarming of underwater autonomous vehicles that deal with the problems mentioned before. At the MAC sublayer, a MAC protocol called 2MAC is introduced. 2MAC improves the throughput of the network using the multichannel capabilities of OFDM at the physical layer. At the logical link control sublayer, a protocol named SW-MER is proposed. SW-MER improves the throughput and the reliability combining the well-known stop and wait protocol with the sliding window strategy, and using an exponential retransmission strategy to deal with errors. 2MAC and SW-MER are evaluated and compared with other protocols using analytical means and simulations. The results show that by using 2MAC, packet collisions are considerably reduced and the throughput improved. In addition, the use of SW-MER improves the packet delivery ratio over existing mechanisms. In general, the evaluations indicate that the proposed data link layer protocols offer a better communication alternative for underwater autonomous vehicles (UAV) than traditional protocols.

The project deals with the creation of graphical applications for iOS system, describes the basics of OpenGL ES 2.0, development environment Xcode, Cocoa Touch Framework and Objective-C language. It focuses on the description of creation OpenGL game in the genre of "line drawing" games.

This work is engaged in access control mechanism in GNU/Linux operating systems. At first discretionary and mandatory access control are compared and examine basic technologies based on mandatory access control. More closely is focused on project SELinux, whose generation of new rules is explained. Within the thesis is made application for logging evaluation and for writing new Type Enforcement rules.

This thesis informs about technologies and architecture of computer network at BUT.  It describes chosen technologies and some of theirs variants.  Further, it contains simulation model design of a network switch device.  That is followed by the model implementation with detailed description of model parts. Then, the model is tested on a set of simulation scenarios and it is evaluated in comparison with theoretical basis and real devices.  In conclusion, thesis suggests future model development and improvements.

This research study took place at the High Performance Centre (hpc) at the University of Pretoria (UP) in South Africa (SA). The sport psychologists/sports counselors at the hpc mainly deliver performance development services to the athletes. The sport psychology services at the hpc are conducted to the athletes via the Psychological Skills Training (PST) approach and Mindfulness-Acceptance-Commitment (MAC) approach. These two approaches are individualistic in nature and the aim of my study was to move away from a more traditional individualistic perspective to an ecological perspective that takes into consideration other role players such as sport scientists. This was achieved by developing a sport science specific MAC programme for the sport scientists, which was facilitated through experiential learning. The goal of the MAC programme was to explore the sport scientists’ experiences with reference to what they discovered and how they applied their learning. Eight in depth, semi-structured interviews were conducted with four sport scientists at the hpc after their participation in the programme. Interpretive Phenomenological Analysis (IPA) was used to analyse the semi-structured interviews. The findings were mainly related to difficulties and advantages that the sport scientists experienced when they applied the MAC principles. / Dissertation (MA)--University of Pretoria, 2016. / Psychology / MA / Unrestricted

Benutzerbestimmte Zugriffskontrolle ist an vielen Stellen schwer zu beschränken und zu administrieren. Der Ansatz der systembestimmten Zugriffskontrolle - Mandatory Access Control - gibt die Verantwortung an das System ab und gibt Benutzern deutlich weniger Rechte. Diese Arbeit vergleicht zwei Vertreter, welche Mandatory Access Control umsetzen, einerseits das Linux Security Module Framework und andererseits das FreeBSD MAC Framework, zudem werden die wichtigsten Policy Vertreter angegeben. Auf beiden Seiten finden sich ähnliche Ansätze wie die Umsetzung als Kernelmodul und vor allem generische Fähigkeiten, allerdings sind die implementierten Funktionalitäten unter FreeBSD im Detail oft besser durchdacht oder auch ausgereifter.

This paper presents a scheduling algorithm for point to point wireless power transfer system (WPTS) to sensor nodes of wireless body area networks (WBAN). Since the sensors of wireless body area networks are continuously monitoring and sending data to remote central unit, power crisis for these sensor nodes degrades the data transfer of patient monitoring system. Although energy harvesting from ambient sources using electromagnetic induction enhances the longevity of sensor performance, continuous operation in the primary side decreases the overall efficiency. With such paradigm in sight, a framework is proposed for increasing the primary battery longevity and reducing the transmission loss, inductive power is transmitted from primary to secondary unit using medium access control (MAC) protocols for underlying the centralized scheduling opportunity in a collision free scheme for channel access of rare yet critical emergency situation. In a preliminary study, the proposed scheduling for charging sensor nodes in a wireless body area network (WBAN) is evaluated in a case consideration.