In both the chemical and mechanical pulping process, the logs are cut into wood chips by a disc chipper before fibre separation. To make the wood chipping process more efficient, one have to investigate in detail the coupling between theprocess parameters and the quality of the chips. The objective of this thesis is to obtain an understanding of the fundamental mechanisms behind the creation of wood chips. Both experimental and analytical/numerical approaches have been taken inthis work. The experimental investigations were performed with an in‐house developed equipment and a digital speckle photography equipment. The results from the experimental investigation showed that the friction between the log and chipping tool is probably one crucal factor for the chip formation. Further more it was found that the indentation process is approximately self‐similar, and that the stress field over the entire crack‐plane is critical for chip creation. The developed analytical model predicts the normal and shear strain distribution. The analytical distributions are in reasonable agreement with the corresponding distributions obtained from a finite element analysis.

The objective of the proposed research is to develop an analytical model that predicts performance and power for many-core architecture and further propose a mechanism, which leverages the analytical model, to enable energy-efficient execution of an application. The key insight of the model is to investigate and quantify a complex relationship that exists between the thread-level parallelism and memory-level parallelism for an application on a given many-core architecture. Two metrics are proposed: memory warp parallelism (MWP), which refers to the number of overlapping memory accesses per core, and computation warp parallelism (CWP), which characterizes an application type. By using these metrics in addition to the architectural and application parameters, the overall application performance is produced. The model uses statically-available parameters such as instruction-mixture information and input-data size, and the prediction accuracy is 13.3% for the GPU-computing benchmarks. Another important aspect of using many-core architecture is reducing peak power and achieving energy savings. By using the proposed integrated power and performance (IPP) framework, the results showed that different optimization points exist for GPU architecture depending on the application type. The work shows that by activating fewer cores, 10.99% of run-time energy consumption can be saved for the bandwidth-limited benchmarks, and a projection of 25.8% energy savings is predicted when power-gating at core level is employed. Finally, the model is shifted to throughput using OpenCL for targeting more variety of processors. First, multiple outputs relating to performance are predicted, including upper-bound and lower-bound values. Second, by using the model parameters, an application can be categorized into a different category, each with its own suggestions for improving performance and energy efficiency. Third, the bandwidth saturation point accuracy is significantly improved by considering independent memory accesses and updating the performance model. Furthermore, a trade-off analysis using architectural and application parameters is straightforward, which provides more insights to improve energy efficiency. In the future, a computer system will contain hundreds of heterogeneous cores. Hence, it is mandatory that a workload gets scheduled to an efficient core or distributed on both types of cores. A preliminary work by using the analytical model to do scheduling between CPU and GPU is demonstrated in the appendix. Since profiling phase is not required, the kernel code can be transformed to run more efficiently on the specific architecture. Another extension of the work regarding the relationship between the speed-up and energy efficiency is mathematically derived. Finally, future research ideas are presented regarding the usage of the model for programmer, compiler, and runtime for future heterogeneous systems.

This thesis amends some existing theoretical gaps and an overall lack of empirical studies regarding the ways R&D managers can use Open Innovation during the management of the radical innovation processes’ early development phase.Using existing theories, an interview guide and an analytical model was created. These were later used during the gathering and analysis of empirical data. Our sampling involves three of Sweden’s largest companies, representing three distinct industry fields. Interviews took place during April 2010, and all the interviewees were R&D managers with previous experience with Open Innovation and radical innovation.The results reveal that the managers do use Open Innovation when managing radical innovation, and point to both benefits and issues brought about by using Open Innovation during this process. The use of Open Innovation during the management of radical innovation can be divided into two main aspects; the actual extent to which it is used, and the ways the managers use it. Our results reveal that the extent varies from an early peak, an in between Open Innovation chasm and a final increase. Furthermore, our studies also show that the main ways the managers use OI are; exploitation and creation of revenue streams, knowledge leveraging and integration, and finally to create superior products using broad knowledge networks.

A generalized ejector model was successfully developed for gas ejector design and performance analysis. Previous 1-D analytical models can be derived from this new comprehensive model as particular cases. For the first time, this model shows the relationship between the cosntant-pressure and constant-area 1-D ejector models. The new model extends existing models and provides a high level of confidence in the understanding of ejector mechanics. “Off-design” operating conditions, such as the shock occurring in the primary stream, are included in the generalized ejector model. Additionally, this model has been applied to two-phase systems including the gas-liquid ejector designed for a Proton Exchange Membrane (PEM) fuel cell system. The equations of the constant-pressure and constant-area models were verified. A parametric study was performed on these widely adopted 1-D analytical ejector models. FLUENT, commercially available Computational Fluid Dynamics (CFD) software, was used to model gas ejectors. To validate the CFD simulation, the numerical predictions were compared to test data and good agreement was found between them. Based on this benchmark, FLUENT was applied to design ejectors with optimal geometry configurations.

It is an internationally acknowledged that marine protected area (MPA) is an important measure for maintaining biodiversity and rescuing endangered species. MPA can also effectively inhibit human interferences such as development and pollution discharge. The establishment of MPA is possible to fulfill the goal of sustainable management, which is to conserve marine habitat for an integrative ecosystem and a higher biodiversity. However, how to design an effective MPA remains an important research issue to be explored. In order to grasp the spatial distribution of the ecological data in the study area, the current research uses spatial interpolation tool, Kriging, provided by the Geographic information system (GIS) software. Then three spatial analytical models have been developed based on integer programming techniques. It is guarantee that all three models can find the global optimal solutions for the best protective area partitions. This quantitative approach is more efficient and effective compared to the qualitative methods in many aspects. The models are able to preserve the maximum ecological resources under the limited spatial area. Besides, the model formulation can be adjusted from different environmental impact factors to fulfill the requirements of users. The case study of the research is to design a MPA for Kaomei wetland. However the spatial analytical models developed in this research can also be applied to protected area design in land area.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Um aspecto particular no dimensionamento de maciços reforçados com geossintéticos consiste na análise da estabilidade interna. A ruptura interna pode ocorrer quando as solicitações impostas ao elemento de reforço superam a resistência à tração, ou quando ocorre o arrancamento do reforço da massa de solo, por ancoragem insuficiente. A distribuição das deformações e das tensões ao longo do comprimento enterrado do reforço não é uniforme, e este aspecto não é considerado no dimensionamento. Desta forma, modelos analíticos e numéricos aparecem como alternativas capazes de reduzir incertezas no dimensionamento de maciços reforçados, permitindo a adoção de soluções menos conservativas. O presente trabalho propõe um modelo analítico para a reprodução do mecanismo de transferência de esforços e deslocamentos ao longo do comprimento de geotêxteis sob condição de arrancamento, e apresenta a modelagem numérica de ensaios de arrancamento, fazendo uso do programa Plaxis, de elementos finitos. A partir dos resultados de um extenso programa experimental de ensaios de arrancamento instrumentados, em geotêxteis (Espinoza,2000), os modelos analítico e numérico foram validados e discutidos. Posteriormente, apresenta-se a simulação de um ensaio de arrancamento hipotético fazendo uso de ambos os modelos. Os resultados sugerem que os modelos analítico e numérico foram adequados na previsão dos esforços, deformações e deslocamentos ao longo do comprimento de geotêxteis em solicitações de arrancamento. Observou-se um melhor ajuste entre as previsões do modelo analítico e os resultados experimentais, justificado pela adoção do modelo não linear para o elemento geotêxtil. A distribuição de esforços e deslocamentos ao longo de geotêxteis é complexa, e a boa concordância dos modelos com os resultados experimentais reforça a potencialidade dos modelos para uso futuro. / The internal stability analysis is a particular aspect in the design of reinforced soil with geotextiles. Internal failure may occur when the stresses transmitted to the reinforcing element exceeds the tensile strength or when it is pulled out, due to insufficient anchorage. The stress strain distribution along the embedded length of the reinforcement is not uniform, and this condition is not incorporated in the design. Thus, analytical and numerical models appear as alternatives to reduce uncertainties in the design of reinforced soil structures, allowing the adoption of less conservative solutions.The present research proposes an analytical model that reproduces load transfer mechanism and displacements along the length of geotextiles under pullout condiction, and also presents a numerical simulation of pullout tests, making use of Plaxis FEM program. Based on the results of an extensive program of pullout tests in instrumented samples of geotextiles (Espinoza, 2000), the analytical and numerical models were validated and discussed. The simulation of a hypothetical pullout test making use of both models is also presented.The results suggest that the analytical and numerical models are suitable to predict loads, strains and displacements along the geotextiles length, submitted to pullout. The analytical model provided a better fit for the experimental results, since it incorporates a non-linear behavior for the geotextile. The distribution of loads and displacements along the geotextiles is complex, and the good agreement between the models and the experimental results emphasizes the capability of the models for further use.

abstract: As the demand of sustainable construction materials increases, use of fibers and textiles as partial or full reinforcement in concrete members present a tremendous opportunity. Proper characterization techniques and design guides for hybrid materials are therefore needed. This dissertation presents a comprehensive study on serviceability-based design of strain softening and strain hardening materials. Multiple experimental procedures are developed to document the nature of single crack localization and multiple cracking mechanisms in various fiber and fabric reinforced cement-based composites. In addition, strain rate effects on the mechanical properties are examined using a high speed servo-hydraulic tension test equipment. Significant hardening and degradation parameters such as stiffness, crack spacing, crack width, localized zone size are obtained from tensile tests using digital image correlation (DIC) technique. A tension stiffening model is used to simulate the tensile response that addresses the cracking and localization mechanisms. The model is also modified to simulate the sequential cracking in joint-free slabs on grade reinforced by steel fibers, where the lateral stiffness of slab and grade interface and stress-crack width response are the most important model parameters. Parametric tensile and compressive material models are used to formulate generalized analytical solutions for flexural behaviors of hybrid reinforced concrete (HRC) that contains both rebars and fibers. Design recommendations on moment capacity, minimum reinforcement ratio etc. are obtained using analytical equations. The role of fiber in reducing the amount of conventional reinforcement is revealed. The approach is extended to T-sections and used to model Ultra High Performance Concrete (UHPC) beams and girders. The analytical models are extended to structural members subjected to combined axial and bending actions. Analytical equations to address the P-M diagrams are derived. Closed-form equations that generate the interaction diagram of HRC section are presented which may be used in the design of multiple types of applications. The theoretical models are verified by independent experimental results from literature. Reliability analysis using Monte Carlo simulation (MCS) is conducted for few design problems on ultimate state design. The proposed methodologies enable one to simulate the experiments to obtain material parameters and design structural members using generalized formulations. / Dissertation/Thesis / Doctoral Dissertation Civil and Environmental Engineering 2016

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Um aspecto particular no dimensionamento de maciços reforçados com geossintéticos consiste na análise da estabilidade interna. A ruptura interna pode ocorrer quando as solicitações impostas ao elemento de reforço superam a resistência à tração, ou quando ocorre o arrancamento do reforço da massa de solo, por ancoragem insuficiente. A distribuição das deformações e das tensões ao longo do comprimento enterrado do reforço não é uniforme, e este aspecto não é considerado no dimensionamento. Desta forma, modelos analíticos e numéricos aparecem como alternativas capazes de reduzir incertezas no dimensionamento de maciços reforçados, permitindo a adoção de soluções menos conservativas. O presente trabalho propõe um modelo analítico para a reprodução do mecanismo de transferência de esforços e deslocamentos ao longo do comprimento de geotêxteis sob condição de arrancamento, e apresenta a modelagem numérica de ensaios de arrancamento, fazendo uso do programa Plaxis, de elementos finitos. A partir dos resultados de um extenso programa experimental de ensaios de arrancamento instrumentados, em geotêxteis (Espinoza,2000), os modelos analítico e numérico foram validados e discutidos. Posteriormente, apresenta-se a simulação de um ensaio de arrancamento hipotético fazendo uso de ambos os modelos. Os resultados sugerem que os modelos analítico e numérico foram adequados na previsão dos esforços, deformações e deslocamentos ao longo do comprimento de geotêxteis em solicitações de arrancamento. Observou-se um melhor ajuste entre as previsões do modelo analítico e os resultados experimentais, justificado pela adoção do modelo não linear para o elemento geotêxtil. A distribuição de esforços e deslocamentos ao longo de geotêxteis é complexa, e a boa concordância dos modelos com os resultados experimentais reforça a potencialidade dos modelos para uso futuro. / The internal stability analysis is a particular aspect in the design of reinforced soil with geotextiles. Internal failure may occur when the stresses transmitted to the reinforcing element exceeds the tensile strength or when it is pulled out, due to insufficient anchorage. The stress strain distribution along the embedded length of the reinforcement is not uniform, and this condition is not incorporated in the design. Thus, analytical and numerical models appear as alternatives to reduce uncertainties in the design of reinforced soil structures, allowing the adoption of less conservative solutions.The present research proposes an analytical model that reproduces load transfer mechanism and displacements along the length of geotextiles under pullout condiction, and also presents a numerical simulation of pullout tests, making use of Plaxis FEM program. Based on the results of an extensive program of pullout tests in instrumented samples of geotextiles (Espinoza, 2000), the analytical and numerical models were validated and discussed. The simulation of a hypothetical pullout test making use of both models is also presented.The results suggest that the analytical and numerical models are suitable to predict loads, strains and displacements along the geotextiles length, submitted to pullout. The analytical model provided a better fit for the experimental results, since it incorporates a non-linear behavior for the geotextile. The distribution of loads and displacements along the geotextiles is complex, and the good agreement between the models and the experimental results emphasizes the capability of the models for further use.

A comparison of the ability of different spatial filters to reduce the amount of crosstalk in a surface electromyography (sEMG) measurement was conducted. It focused on the influence of different properties of the muscle anatomy and detection system used on the amount of crosstalk present in the measurements. An analytical model was developed which enabled the simulation of single fibre action potentials (SFAPs). These fibres were grouped together in motor units (MUs). Each MU has characteristics which, along with the SFAPs, are used to obtain the motor unit action potential (MUAP). A summation of the MUAPs from all the MUs in a muscle leads to the electromyogram (EMG) signal generated by the muscle. This is the first model which simulates a complete muscle for crosstalk investigation. Previous studies were done for single fibres (Farina&Rainoldi 1999; Farina et al. 2002e; Farina et al. 2004a) or MUs (Dimitrova et al. 2002; Dimitrov et al. 2003; Winter et al. 1994). Lowery et al. simulated a complete muscle, but only investigated one spatial filter (Lowery et al. 2003a). This model is thus the first of its kind. EMG signals were generated for limbs with different anatomical properties and recorded with various detection systems. The parameters used for comparison of the recorded signals are the average rectified value (ARV) and mean frequency (MNF), which describe the amplitude and frequency components of an EMG signal, respectively. These parameters were computed for each EMG signal and interpreted to make recommendations on which detection system results in the best crosstalk rejection for a specific experimental set-up. The conclusion is that crosstalk selectivity in an sEMG measurement is decreased by increasing the thickness of the fat layer, increasing the skin conductivity, decreasing the fibre length, increasing the interelectrode distance of the detection system, placing the detection electrodes directly above the end-plate area or an increased state of muscle contraction. Varying the contraction force strength or placing the detection electrodes directly above the tendon area has no influence on the crosstalk selectivity. For most of the conditions investigated, the normal double differential (NDD) detection system results in the best crosstalk reduction. The only exceptions are a set-up with poor skin conductivity where NDD and double differential (DD) performed comparably, and the two simulations in which the muscle length is varied, where the DD filter performed best. Previous studies have found DD to be more selective for crosstalk rejection than NDD (Dimitrov et al. 2003; Farina et al. 2002a; Van Vlugt&Van Dijk 2000). Possible reasons for the contradictory results are the high value of skin conductivity currently used or influences of the muscle geometry. / Dissertation (MEng(Bio-Engineering))--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / unrestricted

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