The United States plans to bury high level radioactive waste from commercial power reactors and from nuclear weapons manufacturing in Yucca Mountain, Nevada. Yucca Mountain, located about 80 miles northwest of Las Vegas, consists of horizontally bedded tuff deposits. Although the region is very arid, enough water exists in the tuffs to create a vapor dominated geothermal system as the pore water evaporates, circulates and recondenses. This study examines how silica leaching might occur as a result of water-tuff interactions in Yucca Mountain after the emplacement of heat-producing nuclear waste canisters. A vertical thermal gradient experiment (VTGE) was designed and built in order to simulate the water cycling scenario where water in the tuff is vaporized by the heat from the canisters, moves to cooler regions along fractures and condenses as a liquid which flows downward toward the hot canisters. This experiment was used to measure the rate of silica leaching from Yucca Mountain tuff at various heat fluxes. The results show that under the experimental conditions silica is leached from the tuff sample very effectively (about 1.85 x 10 -8 g per Joule of heat transferred). With such a rate, significant amount of amorphous silica (135 kg per canister for the first 1,000 years after emplacement) could be leached, transported and deposited above the repository horizon; the resulting low permeability zone might change the geological and hydrological properties of the host rock. A significant amount of colloidal silica was formed in the solution soon after the water recycling began. Such colloidal silica could adsorb and transport radionuclides released from breached waste canisters more efficiently than that when radionuclides act alone. The results indicate that silica leaching is a potential problem for the current designs of the Yucca Mountain repository. / Master of Science

I detta arbete har en trådad simulator tagits fram enligt standarden High Level Architecture (HLA). Simulatorn är kapabel att avgöra den kortaste vägen från alla noder till alla andra noder i ett radionätverk med 200 noder på i genomsnitt 263 millisekunder. Tidigare var det endast möjligt att simulera kommunikation mellan två noder i ett nätverk som hade direkt förbindelse med varandra. I och med detta tillägg kan kommunikationssignalen reläas fram genom nätverket om en direkt förbindelse inte är möjlig. Simulatorn, eller federatet som det kallas i HLA, bygger på en centraliserad routingalgoritm och kan konfigureras till att beräkna specifika vägar på begäran alternativt beräkna alla möjliga vägar genom nätverket utan att någon efterfrågan behövs. Simulatorn använder sig av en A*-algoritm som kan använda en av två heuristiker där den ena heuristiken tar fram den kortaste vägen mellan två noder i nätverket och den andra heuristiken tar fram den väg med bäst signalkvalitet mellan två noder. / This paper presents a threaded simulator designed according to the standard High Level Architecture (HLA). The simulator is capable of determining the shortest path from all nodes to all other nodes in a radio network with 200 nodes in 263 milliseconds on average. It was previously only possible to simulate communication between two nodes which had direct connection. As of this addition, the communication can be relayed through other nodes in the network if direct connection is not possible. The simulator, or federate as it is called in HLA, implements a centralised routing algorithm and can be configured to find specific paths on the basis of requests alternatively find all paths through the network without the need for any request. The simulator uses an A* (A-star) algorithm which can use one of two heuristics, one of which returns the shortest path and the other returns the path with the best signal quality.

Clay formations are investigated worldwide as potential host rock for the deep geological disposal of high-level radioactive waste (HLW). Usually bentonite is preferred as the buffer and backfill material in the disposal system. In the disposal of HLW, heat emission is one of the most important issues as it can generate a series of complex thermo-hydro-mechanical (THM) processes in the surrounding materials and thus change the material properties. In the context of safety assessment, it is important to understand the thermally induced THM interactions and the associated change in material properties. In this work, the thermally induced coupled THM behaviours in the clay host rock and in the bentonite buffer as well as the corresponding coupling effects among the relevant material properties are numerically analysed. A coupled non-isothermal Richards flow mechanical model and a non-isothermal multiphase flow model were developed based on the scientific computer codes OpenGeoSys (OGS). Heat transfer in the porous media is governed by thermal conduction and advective flow of the pore fluids. Within the hydraulic processes, evaporation, vapour diffusion, and the unsaturated flow field are considered. Darcy’s law is used to describe the advective flux of gas and liquid phases. The relative permeability of each phase is considered. The elastic deformation process is modelled by the generalized Hooke’s law complemented with additional strain caused by swelling/shrinkage behaviour and by temperature change. In this study, special attention has been paid to the analysis of the thermally induced changes in material properties. The strong mechanical and hydraulic anisotropic properties of clay rock are described by a transversely isotropic mechanical model and by a transversely isotropic permeability tensor, respectively. The thermal anisotropy is described by adoption of the bedding-orientation-dependent thermal conductivity. The dependency of the thermal conductivity on the degree of water saturation, the dependency of the thermal effects on the water retention behaviour, and the dependency of the effects of the pore pressure variation on the permeability and the anisotropic swelling/shrinkage behaviour have been intensively analysed and the corresponding numerical models to consider those coupling effects have been developed. The developed numerical model has been applied to simulate the laboratory and in situ heating experiments on the bentonite and clay rock at different scales. Firstly the laboratory heating experiment on Callovo-Oxfordian Clay (COX) and the laboratory long-term heating and hydration experiment on MX80 pellets were simulated. Based on the knowledge from the numerical analysis of the laboratory experiments, a 1:2 scale in situ heating experiment of an integrated system of the bentonite engineered barrier system (EBS) in the Opalinus Clay host rock was simulated. All the relevant operation phases were considered in the modelling. Besides, the modelling was extended to 50 years after the heat shut-down with the aim of predicting the long-term behaviours. Additionally, variation calculations were carried out to investigate the effects of the storage capacity of the Opalinus Clay on the thermally induced hydraulic response. In the long-term modelling, the effects of different saturated water permeabilities of buffer material on the resaturation process were analysed. Based on the current researches and model developments, the observed THM behaviours of the bentonite buffer and the clay rock, that is, the measured evolution of temperature, pore pressure, humidity, swelling pressure, and so on in the laboratory and in situ experiments can be reproduced and interpreted well. It is proved that by using both a non-isothermal multiphase flow model and a non-isothermal Richards flow model combined with the corresponding thermal and mechanical models, the major THM behaviours can be captured. It is validated that the developed model is able to simulate the relevant coupled THM behaviours of clayey material under the well-defined laboratory conditions as well as under the complex natural disposal conditions.

Modern systems fulfil calculation tasks across the hardware- software boundary. Tasks are divided into coarse parallel subtasks that run on distributed resources. These resources are classified into a software (SW) and a hardware (HW) domain. The software domain usually contains processors for general purpose or digital signal calculations. Dedicated co-processors such as encryption or video en-/decoding units belong to the hardware domain. Nowadays, a decision in which domain a certain subtask will be executed in a system is usually taken during system level design. This is done on the basis of certain assumptions about the system requirements that might not hold at runtime. The HW/SW partitioning is static and cannot adapt to dynamically changing system requirements at runtime. Our contribution to tackle this, is to combine a ESL based HW/SW codesign methodology with a coarse grained reconfigurable System on Chip architecture. We propose this as Preemptive HW/SW-Threading.

Today’s embedded systems depend on the availability of hybrid platforms, that contain heterogeneous computing resources such as programmable processors units (CPU’s or DSP’s) and highly specialized hardware cores. These platforms have been scaled down to integrated embedded system-on-chip. Modern platform FPGAs enhance such systems by the flexibility of runtime configurable silicon. One of the major advantages that arises is the ability to use hardware (HW) and software (SW) resources in a time-shared manner. Though the ability to dynamically assign computing resources based on decisions taken at runtime is given.

Submitted by Fernando Souza (fernandoafsou@gmail.com) on 2017-08-21T13:50:24Z No. of bitstreams: 1 arquivototal.pdf: 2220137 bytes, checksum: 5d830e5d1ba6396c3e9ff56a19b08deb (MD5) / Made available in DSpace on 2017-08-21T13:50:24Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2220137 bytes, checksum: 5d830e5d1ba6396c3e9ff56a19b08deb (MD5) Previous issue date: 2016-02-26 / Multi-Robot System (MRS) consisting of multiple interacting robots, each running a specific control strategy, which is not driven centrally. Technical challenges arise from the need to develop complex, software-intensive products that take the constraints of the physical world into account. Make tools, methodologies and teams from different fields can work together is not an easy task to accomplish. Co-simulation represents on technique of validation in heterogeneous systems. Its fundamental principle is to provide support to execute different simulators in a cooperative way. A known standard is the High Level Architecture (HLA) that is a pattern described in IEEE 1516 series and has been developed to provide a common architecture to distributed model and simulation. Using HLA, several simulators and real applications could be simulated together. That way, this work presents a project for Multi-Robot Systems (SMR) simulation using ROS co-simulation with a network simulator, the OMNeT++, using HLA. The main goal is make the simulations more realistic, where the data exchange will be performed by using a simulated network, as if we had real robots interacting through a conventional network. To this end, an interface was developed between ROS and OMNeT++ using HLA. Experiments demonstrate that the packet losses were correctly simulated, adding realism to simulations. / Sistemas Multi-Robôs (SMR) consistem em múltiplos robôs interagindo, cada um executando uma estratégia de controle específica, que não é conduzida de forma centralizada. Alguns desafios surgiram da necessidade de desenvolver produtos que levem o mundo real em consideração. Fazer com que ferramentas, metodologias e equipes de diferentes áreas possam trabalhar juntas não é uma tarefa simples de ser realizada. Cossimulação representa uma técnica para validação de sistemas heterogêneos. Seu princípio fundamental é prover suporte à execução de diferentes simuladores de forma cooperativa. Um dos padrões para tal é conhecido como High Level Architecture (HLA), que é um padrão descrito no IEEE 1516 e tem sido desenvolvido para dispor uma arquitetura para modelagem e simulação distribuídos. Utilizando HLA, vários simuladores e aplicações reais podem ser simulados juntos. Sendo assim, este trabalho apresenta um projeto para simulação de Sistemas Multi-Robôs (SMR) utilizando ROS cossimulado com um simulador de redes de computadores, o OMNeT++ através do HLA. Seu principal objetivo é tornar as simulações mais próximas da realidade, onde os dados irão ser trocados através de uma rede simulada, como se tivéssemos robôs reais interagindo através de uma rede convencional. Para tal, foi desenvolvida a interface entre o ambiente ROS e o OMNeT++ com o HLA. Experimentos demonstraram que a perda de pacotes foi simulada corretamente, adicionando ao ambiente mais realismo

This project describes the implementation of an LZ4 compression algorithm in a C/C++-like language, that can be used to generate VHDL programs for FPGA integrated circuits embedded in accelerated network interface controllers (NICs). Based on the algorithm specification, software versions of LZ4 compressor and decompressor are implemented, which are then transformed into a synthesizable language, that is then used to generate fully functional VHDL code for both components. Execution time and compression ratio of all implementations are then compared. The project also serves as a demonstration of usability and influence of high-level synthesis and high-level approach to design and implementation of hardware applications known from common programming languages.

Master of Science / Department of Computing and Information Sciences / Gurdip Singh / TinyOS is a component based operating system written in nesC programming language. TinyOS provides interfaces and components for common low level abstractions such as packet communication, routing and sensing for node level sensor network application programming. This project aims to provide high level abstractions to users by providing the notion of a virtual node, which represents a set of physical nodes, allowing users to specify global scenarios, and a mechanism to decompose a high level global scenario into local node level scenarios for each of the individual sensor nodes. A global scenario with virtual components, provided by the user, is first converted into a global scenario by eliminating the virtual components from the model by using a mapping information provided the user and replacing these virtual components by their respective physical components. Appropriate algorithm components and the automatically generated adapter components for these algorithm components are then plugged-in to implement inter-node interactions. This global scenario is then converted to the node level local scenarios by introducing the automatically generated proxy components for the remote components and connecting these proxy components using the RMI layer. The Cadena model is modified to include the attribute location for the components to identify the remote components. The make files are then generated for these local scenarios and are ready to be deployed on the physical motes. The framework provides a GUI tool which is used to visualize the data of the sensor network in both simulation and deployment. The framework provides the user with commands that can be issued to the network from the Cadena component model as a set of interfaces to the components and a python script is used to capture this information in an xml file. The Cadena model is modified to include the attribute observable to the interfaces to identify them as the GUI commands. The GUI loads this XML file and the topology file for the actual deployment, can issue commands to the network and displays the results to the user. The GUI tool also enhances the Tossim simulator to model the external effects over the sensor network and to place the motes based on the topology information using the Tython environment.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / In this paper we propose an open multi-robot architecture that dramatically reduces the time to deployment and increases the utility value to the mainstream non-technical user. We describe a multi-robot behavior-based coordination architecture and argue its suitability in the context of general-purpose robot teams operating in dynamic and unpredictable environments. We then formalize and describe a command fusion module for the coordination of high-level behaviors of the system. The command fusion module is interfaced to our middle-ware/compiler that generates behavior selection tips from a user specified abstract description of a scenario. Finally, we utilize an example search and rescue scenario to illustrate the overall process and give preliminary results of the experiments performed on actual robots.

International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Loral Instrumentation System 500 configured as an Advanced Commanding and Telemetry System (ACTS) supports the acquisition of multiple telemetry downlink streams, and simultaneously supports multiple uplink command streams for today’s satellite vehicles. By using industry and federal standards, the system is able to support, without relying on a host computer, a true distributed dataflow architecture that is complemented by state-of-the-art RISC-based workstations and file servers.