There has been a significant rise of users in the 3D-printer community. A common dilemma amongst users is how to handle spools of plastic filament that does not contain enough filament for an arbitrary print. This report explores the possibility of fusing strands of filament together from two different spools into one spool by the method of fusion bonding. This concept of plastic bonding generally consists of the following three steps. Preparing the surface area, heating the polymer and physically pushing the filament strands on to each other. Fusion bonding proved to be successful for temperatures between 150-190 ◦C without reducing required tensile strength for printing. There was a clear deterioration in the ability to follow tight curves for the fused filament. This showed in the result where many of the welded strands snapped when conducting the bending test. The welded filament had an average diameter of 1.992 mm. It appears that the filament bond formed based on the geometry of the PTFE tube that acted like a mold. It was concluded that the welded filament bond could improve if the used PTFE-tube had a diameter closer to 1.75 mm. Possible improvements were discussed where an example of using PTFE coating could improve the quality of the fuse in terms of strand diameter. / Användningen av 3D-skrivare har ökat markant bland konsumenter. En vanlig situation som uppstår är att kvarvarande filamentrulle inte har tillräckligt med material över för en godtycklig utskrift. Den här rapporten avser att behandla möjligheten att svetsa ihop två olika plasttrådar av filament till en enda tråd och därefter rulla ihop den sammansvetsade plasten till en filamantrulle. Metoden som användes för att utföra svetsningen kallas för fusion bonding. Det finns flera olika varianter av denna metod. För att utföra sammansvetsning med fusion bonding krävs följande tre steg, förberedelse av ytan på den tilltänkta svetsen, upphettning av polymererna och därefter fysiskt röra de upphettade polymererna mot varandra tills kontakt uppstår. Fusion bonding visade sig vara en fungerande metod att sammansvetsa filament med för temperaturer mellan 150-190◦C utan att påverka den nödvändiga styrkan för att klara av en utskrift. Böjtestet påvisade en kraftig försämring av det sammansvetsade materialets förmåga att böja sig. Det visade sig även att medeldiametern vid sammansvetsningen var 1.992 mm. Slutsatsen som drogs av resultatet var att sammansvetsningen formade sig efter PTFE-tuben som agerade som en form åt polymererna. En möjlig förbättring som diskuterades var att använda PTFE-beläggningpå aluminiumblocket för att minska skillnaden i diametern mellan sammansvetsningen och originaldiametern.

<p dir="ltr">Dynamic analysis of embedded firmware is a necessary capability for many security tasks, e.g., vulnerability detection. Rehosting is a technique that enables dynamic analysis by facilitating the execution of firmware in a host environment decoupled from the actual hardware. Current rehosting techniques focus on high-fidelity execution of the entire firmware. Consequently, these techniques try to execute firmware in an emulated environment, with precise models of hardware (i.e., peripheral) interactions. However, these techniques are hard to scale and have various drawbacks. </p><p dir="ltr">Therefore, a novel take on rehosting is proposed by focusing on the application components and their interactions with the firmware without the need to model hardware dependencies. This is achieved by rehosting the embedded application as a Linux application. In addition to avoiding precise peripheral modeling, such a rehosting technique enables the use of existing dynamic analysis techniques on these embedded applications. The feasibility of this approach is demonstrated first by manually performing the rehosting on real-world embedded applications. The challenges in each of the phases – retargeting to x86-64, peripheral handling, and fuzzing the rehosted applications are elaborated. Furthermore, automated steps for retargeting to the x86-64 and peripheral handling are developed. The peripheral handling achieves 89% accuracy if reserved regions are also considered. The testing of these rehosted applications found 2 previously unknown defects in driver components.</p>

The proliferation of embedded systems into nearly every aspect of modern infrastructure and society has seen their deployment in such diverse roles as monitoring the power grid and processing commercial payments. Software intellectual property (SWIP) is a critical component of these increasingly complex systems and represents a significant investment to its developers. However, deeply immersed in their environment, embedded systems are difficult to secure. As a result, developers want to ensure that their SWIP is protected from being reverse engineered or stolen by unauthorized parties. Many techniques have been proposed to address the issue of SWIP protection for embedded systems. These range from secure memory components to complete shifts in processor architectures. While powerful, these approaches often require the development of systems from the ground up or the application of specialized and often expensive hardware components. As a result they are poorly suited to address the security concerns of legacy embedded systems or systems based on commodity components. This work explores the protection of SWIP on heavily constrained, legacy and commodity embedded systems. We accomplish this by evaluating a generic embedded system to identify the security concerns in the context of SWIP protection. The evaluation is applied to determine the limitations of a software only approach on a real world legacy embedded system that lacks any specialized security hardware features. We improve upon this system by developing a prototype system using only commodity components. Finally we propose a Portable Embedded Software Intellectual Property Security (PESIPS) system that can easily be deployed as a framework on both legacy and commodity systems. / Master of Science

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The development of an integrated avionics system containing all the required sensors and actuators for autopilot control is presented. The thesis analyzes the requirements for the system and presents detailed hardware design. The architecture of the system is based on an FPGA which is tasked with interfacing with the sensors and actuators. The FPGA abstracts a microprocessor from these interface modules, allowing it to focus only on the control and user interface algorithms. Firmware design for the FPGA, as well as a conceptualization of the microprocessor software design is presented. Simulation results showing the functionality of firmware modules are presented. / AFRIKAANSE OPSOMMING: Die ontwikkeling van ‘n geïntegreede avionika‐stelsel wat al die vereiste sensors en aktueerders vir outoloods‐beheer bevat, word voorgestel. Die tesis analiseer die vereistes van die stelsel en stel ‘n hardeware‐ontwerp voor. Die argitektuur van die stelsel bevat ‘n FPGA wat ‘n koppelvlak met sensors en aktueerders skep. Die FPGA verwyder die mikroverwerker weg van hierdie koppelvlak modules en stel dit sodoende in staat om slegs op die beheer en gebruikerskoppelvlak‐algoritmes te fokus. Sagteware‐ontwerp vir die FPGA, asook die konseptualisering van die sagtewareontwerp vir die mikroverwerker, word aangebied. Simulasie resultate wat die funksionaliteit van die FPGA‐sagteware modules aandui, word ook voorgestel.

abstract: The manufacturing process for electronic systems involves many players, from chip/board design and fabrication to firmware design and installation. In today's global supply chain, any of these steps are prone to interference from rogue players, creating a security risk. Manufactured devices need to be verified to perform only their intended operations since it is not economically feasible to control the supply chain and use only trusted facilities. It is becoming increasingly necessary to trust but verify the received devices both at production and in the field. Unauthorized hardware or firmware modifications, known as Trojans, can steal information, drain the battery, or damage battery-driven embedded systems and lightweight Internet of Things (IoT) devices. Since Trojans may be triggered in the field at an unknown instance, it is essential to detect their presence at run-time. However, it isn't easy to run sophisticated detection algorithms on these devices due to limited computational power and energy, and in some cases, lack of accessibility. Since finding a trusted sample is infeasible in general, the proposed technique is based on self-referencing to remove any effect of environmental or device-to-device variations in the frequency domain. In particular, the self-referencing is achieved by exploiting the band-limited nature of Trojan activity using signal detection theory. When the device enters the test mode, a predefined test application is run on the device repetitively for a known period. The periodicity ensures that the spectral electromagnetic power of the test application concentrates at known frequencies, leaving the remaining frequencies within the operating bandwidth at the noise level. Any deviations from the noise level for these unoccupied frequency locations indicate the presence of unknown (unauthorized) activity. Hence, the malicious activity can differentiate without using a golden reference or any knowledge of the Trojan activity attributes. The proposed technique's effectiveness is demonstrated through experiments with collecting and processing side-channel signals, such as involuntarily electromagnetic emissions and power consumption, of a wearable electronics prototype and commercial system-on-chip under a variety of practical scenarios. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2020

This work deals with virtualization of computer systems and network cards in high-speed computer networks, and describes implementation of the SR-IOV virtualization technology support in the COMBO network card platform. Various approaches towards network card virtualization are compared, and the benefits of the SR-IOV technology for high performance applications are described. The work gives overview of the COMBO platform and describes design and implementation of the SR-IOV technology support for the COMBO platform. The work concludes with measurement and analysis of the implemented technology performance in virtual machines. The result of this work is the COMBO cards' support for the SR-IOV technology, which makes it possible to use them in virtual machines with wire-speed performance preserved. This allows future COMBO cards to be used as accelerators in the networks utilizing the Network Function Virtualization.

Aktuální postup testování je příliš zdlouhavý a nepřesný, zároveň není měření některých vlastností motoru vůbec možné. Hlavním úkolem zařízení je zrychlení a zjednodušení procesu testování spolu s možností otestovat všechny vlastnosti motorů. Realizace zařízení začala definováním požadavků zákazníka, dalším krokem byla analýza daných požadavků a návrh zařízení. Následovala výroba a programovaní firmwaru spolu se softwarem. Výsledkem práce je funkční přístroj schopný automatického testování sedmi základních typů motorů, měření všech požadovaných funkcí spolu s novou možností měření počtu tiků enkodéru, periody FG signálu z řídící elektroniky BLDC motorů a napěťové úrovně těchto signálů. Dalšími rozšířeními jsou možnost uložení výsledků z uskutečněných testů pro možné budoucí využití a možnost vizualizace proudu motorem. Uživatel je tedy schopný otestovat velké množství motorů v kratším časovém úseku a zároveň se o testovaných motorech dozvědět mnohem více informací než doposud.

This thesis deals with methods of remote maintenance of microcontroller systems based on Atmel AVR family over the Ethernet interface and TCP/IP protocols. To create communication through TCP/IP, an embedded server NE-4100T is used. At the beginning, key features of the server and methods of handling with content of a program memory are discussed. The final solution is based on the bootloader method. It includes bootloader firmware and user program for PC. The hardware part covers design of interconnection electronics, DC-DC step down converter, real time clock and printed circuit board. The remote maintenance of program memory has been sucessfully solved, but the embedded server NE-4100T produces a problem with an auhentification without a sufficient solution.

This thesis treats concept of autonomous temperature, relative humidity and pressure USB datalogger. Also there is explained datalogger function, hardware design with respect on device consumption and design of chassis. Furthermore, there is described communication protocol for control and reading out data by the PC. Furthermore, there are described firmware drivers for some used components and modules for USB communication, RTC and data compression. Lastly there is described software which is used for datalogger configuration and data read out.

Diploma thesis is about narrowband PLC communication standards. The theoretical part describes details of all available OFDM standards including G3-PLC, PRIME, IEEE-1901.2 and G.hnem. The practical part deals with PRIME and G3-PLC standards. In this part is also compared OFDM technology with system of single carrier frequency in environment with real interferences. The last part describes developement of two firmwares for PLC modems Texas Instruments TMDSPLCKIT-V3, which allow UART communication and remote data collection. The thesis also includes Windows application developed to display and save collected data.