QEMU is a machine emulator that is able to emulate environment of various hardware platforms, including PC, PowerPC, ARM and SPARC. The goal of this master thesis is to port QEMU to HelenOS, thus allowing developers run the emulation of HelenOS inside HelenOS. The thesis contains a detailed analysis of the possible porting approaches (including the port of prerequisite libraries or their replacements) and an analysis of the features of QEMU (a reasonable subset of all features of QEMU) that are essential for achieving the goal and features that can be omitted in the prototype implementation. The primary focus of the implementation is to support the PC (x86 and x86-64) guest environment. Although not part of the prototype implementation, the thesis also focuses on analyzing the requirements for running QEMU as a virtualization hypervisor in HelenOS. Powered by TCPDF (www.tcpdf.org)

Developing analytical models that can accurately describe behaviors of Internet-scale networks is difficult. This is due, in part, to the heterogeneous structure, immense size and rapidly changing properties of today's networks. The lack of analytical models makes large-scale network simulation an indispensable tool for studying immense networks. However, large-scale network simulation has not been commonly used to study networks of Internet-scale. This can be attributed to three factors: 1) current large-scale network simulators are geared towards simulation research and not network research, 2) the memory required to execute an Internet-scale model is exorbitant, and 3) large-scale network models are difficult to validate. This dissertation tackles each of these problems. First, this work presents a method for automatically enabling real-time interaction, monitoring, and control of large-scale network models. Network researchers need tools that allow them to focus on creating realistic models and conducting experiments. However, this should not increase the complexity of developing a large-scale network simulator. This work presents a systematic approach to separating the concerns of running large-scale network models on parallel computers and the user facing concerns of configuring and interacting with large-scale network models. Second, this work deals with reducing memory consumption of network models. As network models become larger, so does the amount of memory needed to simulate them. This work presents a comprehensive approach to exploiting structural duplications in network models to dramatically reduce the memory required to execute large-scale network experiments. Lastly, this work addresses the issue of validating large-scale simulations by integrating real protocols and applications into the simulation. With an emulation extension, a network simulator operating in real-time can run together with real-world distributed applications and services. As such, real-time network simulation not only alleviates the burden of developing separate models for applications in simulation, but as real systems are included in the network model, it also increases the confidence level of network simulation. This work presents a scalable and flexible framework to integrate real-world applications with real-time simulation.

Wildfire is the primary natural disturbance in Interior Cedar-Hemlock (ICH) forests, and since the mid-20th century, forest harvesting (clearcutting, in this case) has become the primary anthropogenic disturbance type. Forest management in British Columbia is currently governed by a paradigm that maintains that biological diversity can be preserved by utilizing forest harvesting regimes that closely mimic "natural" disturbance regimes, but a question remains as to how closely these regimes mimic wildfire disturbances. More specifically, how do clearcutting and wildfires compare in their effects on the structure and composition of early-successional ICH plant communities? This study compares vegetation structure, composition, relative abundance and diversity among 39 sites that experienced either a stand-replacing fire or a clearcut within the last 40 years. Sites of different ages and disturbance types were located within the wet cool ICHwkl and very-wet cool ICHvk I biogeoclimatic variants near Revelstoke, B.C. For each site, overstory structural characteristics (tree and snag diameters, basal area and density), overstory composition, and surface fuels (volume of coarse woody debris (CWD)) were assessed. Understory vegetation percent cover, species richness, composition and diversity were also determined. Linear regression analysis was used to examine differences in each of these variables between disturbance types, over time. The trends in structural legacies (especially snag and CWD dynamics) varied greatly between wildfire and clearcut sites. Compared to burned sites, clearcut sites exhibited patterns of accelerated succession in several characteristics (overstory tree regeneration, vegetation cover and understory species richness) due to planting treatments and pre-disturbance relicts. Understory species composition also varied between disturbances, with clearcut sites containing more shade-tolerant survivors initially. Both disturbance types had similar levels of floristic diversity during early succession. These results suggest that clearcut harvesting may not emulate stand-replacing fires in terms of impact on early ICH plant succession in any aspect but diversity. However, it is unclear if these early-successional differences will continue through time. There is a need for further research in this ecosystem, as well as any other ecosystems where emulation silviculture is applied, in order to confirm that silvicultural effects mimic those of natural disturbance regimes. / Forestry, Faculty of / Graduate

The master thesis discusses the design of an emulator of a CPU architecture instruction set aimed at assembly languages course. While most of nowadays emulators are architecture specific, the emulator proposed in master thesis aims at education and better understanding of assembly languages. The emulator is not limited to a single CPU, but it easily allows defining a purpose-specific architecture and instruction set in order to perform operations upon it and to display its current state.

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Cognitive Radio (CR) capitalizes advances in signal processing and radio technology and is capable of reconfiguring RF and switching to desired frequency bands. It is a frequency-agile data communication device that is vastly more powerful than existing multi-channel multi-radio (MC-MR) technology. In this thesis, we investigate the important problem of multi-hop networking with CR nodes. In a CR network, each node has a set of frequency bands (not necessarily of equal size) that may not be the same as those at other nodes. The uneven size of frequency bands prompts the need of further division into sub-bands for optimal spectrum sharing. We characterize behaviors and constraints for such multi-hop CR network from multiple layers, including modeling of spectrum sharing and sub-band division, scheduling and interference constraints, and flow routing. We give a formal mathematical formulation with the objective of maximizing the network throughput for a set of user communication sessions. Since such problem formulation falls into mixed integer non-linear programming (MINLP), which is NP-hard in general, we develop a lower bound for the objective by relaxing the integer variables and linearization. Subsequently, we develop a nearoptimal algorithm to this MINLP problem. This algorithm is based on a novel sequential fixing (SF) procedure, where the integer variables are determined iteratively via a sequence of linear program (LP). In order to implement and evaluate these algorithms in a controlled laboratory setting, we design and implement an emulation testbed. The highlights of our experimental research include: • Emulation of a multi-hop CR network with arbitrary topology; • An implementation of the proposed SF algorithm at the application layer; • A source routing implementation that can easily support comparative study between SF algorithm and other schemes; • Experiments comparing the SF algorithm with another algorithm called Layered Greedy Algorithm (LGA); • Experimental results show that the proposed SF significantly outperforms LGA. In summary, the experimental research in this thesis has demonstrated that SF algorithm is a viable algorithm for optimal spectrum sharing in multi-hop CR networks. / Master of Science

Seamless interconnection of smart mobile devices and cloud services is a key goal in modern mobile computing. Mobile Cloud Computing is the holistic integration of contextually-rich mobile devices with computationally-powerful cloud services to create high value products for end users, such as Apple's Siri and Google's Google Now product. This coupling has enabled new paradigms and fields of research, such as crowdsourced data collection, and has helped spur substantial changes in research fields such as vehicular ad hoc networking. However, the growth of Mobile Cloud Computing has resulted in a number of new challenges, such as testing large-scale Mobile Cloud Computing systems, and increased the importance of established challenges, such as ensuring that a user's privacy is not compromised when interacting with a location-aware service. Moreover, the concurrent development of the Infrastructure as a Service paradigm has created inefficiency in how Mobile Cloud Computing systems are executed on cloud platforms. To address these gaps in the existing research, this dissertation presents a number of software and algorithmic solutions to 1) preserve user locational privacy, 2) improve the speed and effectiveness of deploying and executing Mobile Cloud Computing systems on modern cloud infrastructure, and 3) enable large-scale research on Mobile Cloud Computing systems without requiring substantial domain expertise. / Ph. D.

Thesis advisor: Josh Seim / In this thesis, I examine the productivity of emulation experiences as they relate to building empathy for systems of oppression by utilizing Dinner in the Dark, a vision impairment simulation dinner, hosted by the Boston College Undergraduate Government of Boston College Council for Students with Disabilities, as a case study. Drawing from semi-structured qualitative interviews with 19 participants of Dinner in the Dark and field notes taken on site of both nights of the dinner, I find that developing empathy or experiencing an increase in empathy following Dinner in the Dark did not always necessarily translate into an inclusive and non-stereotypical understanding of the visually impaired disabled identity. In other words, although simulation may promote empathy, emulating a state of being that one is not naturally in possession of, especially if it is also for a brief period, may provide misleading information as well as prompt discrimination. / Thesis (BA) — Boston College, 2024. / Submitted to: Boston College. Morrissey School of Arts and Sciences. / Discipline: Sociology. / Discipline: Departmental Honors.

Genom att använda sig utav en virtuell kopia utav en produktionscell kan programmering och funktionstester av olika paneler testas i ett tidigt stadie. En virtuell kopia bidrar också till enklare felsökning och minskning av kostnader vid idrifttagning. Tanken med projektet är att undersöka i vilken utsträckning som emuleringsmodellen kan ersätta den riktiga cellen vid ett funktionstest för leverantören. Det som också undersöks är i vilken utsträckning riktiga CAD-ritningar kan användas och vilka krav som ställs på ritningarna för att underlätta emulering. Projektet hade flera utmaningar och en av dem som uppkom under projektets gång var problemet med att det inte gick att emulera säkerhetssystemen. Detta löstes genom att bygla alla säkerhetskretsar i PLC-programmet. En viktig del i emulering är kommunikation mellan de olika programvarorna i systemet. I projektets visade det sig fördelaktigt att dela upp programmen i emuleringssystemet för att fördela resurserna över tre datorer. Att använda sig utav en emuleringsmodell istället för en riktig produktionscell är fortfarande i forskningsstadiet men genom projektet har många användningsområden identifierats och skulle kunna förändra idrifttagning i framtiden. / Using a virtual twin of a production cell, makes it possible for programming and different functional testing of panels to be performed in early stages of development. A virtual twin contributes to a simpler debugging and to identify problems and minimize cost in commissioning of the production cell. The aim for the project is to investigate how well an emulated cell will perform compared to the real production cell in a factory acceptance test. Another objective is to investigate how you can use real CAD models in the emulation and what type of criteria the models should meet. The project had a lot of challenges and one of them was the difficulty to emulate the safety systems. This was solved by bypassing the safety in the PLC program. One important thing about emulation is communication between the different software used in the system. In this project, it proved successful to distribute the software on three computers to ease the workload of the programs used in the emulation. To use the emulated model instead of the real system is still in the research phase but in this project a lot of useful applications could be identified that could change commissioning in the future.