The strain capacity of structures depends on the plastic hinge behaviour. There are different proposals in the scientific literature in order to improve this behaviour in reinforced concrete structures such as the following ones: proposals include the use of fiber reinforced concrete, very high performance concrete or replacing in the critical structure zone, the steel reinforcement with shape memory alloy and superelasticity bars (from this point forward SMA), among other solutions. However, the strain capacity of hinges is dependent on the compressed reinforcement buckling, which means a drastic diminishing in the bearing capacity and ductility. This phenomenon happens due to the cover spalling or degradation, or due to an insufficient transverse reinforcement arrangement. The design codes propose requirements related to the diameter of longitudinal bars and to the transverse reinforcement separation to assure the bearing capacity or to assure the hinge rotation without the compressed reinforcements buckle. Nevertheless, the aforementioned requirements are not valid in compressed elements made of new materials (fiber reinforced concrete, very high performance concrete or SMA bars). This doctoral thesis analyzes the compressed steel or NiTi - SMA bars behaviour in elements made of conventional, high strength or very high performance concrete, with or without fibres. Therefore, an experimental research has been carried out to study the local instability of the compressed bars (steel and NITI) in concrete elements. 32 columns subject to a bending-compression load have been analyzed. An analytic model has been proposed to analyze the buckling critical stress and length in the compressed bars in concrete elements. This model has been calibrated based on experimental tests. It has been performed an experimental and numerical research to analyze the behaviour of the NITI bars as isolated bars. It has been proposed an analytic model to calculate the relationship stress-strain of the compressed bars that includes the buckling effect. This model has been verified by both experimental and numerical results. Finally, it has been proposed an expression to calculate the maximum separation of the transverse reinforcement according to the required limited stress, for both steel and SMA bars. In order to define that stress, two criteria have been proposed: one of them is based on stresses and the other one on strains. With respect to the concrete without fibres case, the proposed expression has been compared with the current code. / La capacidad de deformación de las estructuras depende del comportamiento de las rótulas plásticas. Para mejorar dicho comportamiento en estructuras de hormigón armado, en la literatura técnica se propone utilizar hormigón con fibras de acero en su masa, hormigón de muy altas prestaciones o sustituir en la zona crítica de la estructura las armaduras de acero por barras de aleación con memoria de forma y superelasticidad (en adelante SMA) entre otras soluciones. Sin embargo, la capacidad de deformación de las rótulas está condicionada por el pandeo de la armadura comprimida, lo que supone una disminución drástica de la capacidad resistente y de la ductilidad. Este fenómeno se produce porque el recubrimiento del hormigón salta o se degrada, o por una insuficiente disposición de armadura transversal. En las normativas de diseño se proponen requisitos acerca del diámetro y de la separación de la armadura transversal para asegurar la capacidad resistente o la deformación de la rótula sin que las armaduras comprimidas pandeen. Sin embargo, dichas expresiones no son válidas en elementos comprimidos fabricados con nuevos materiales (hormigón con fibras en su masa, hormigones de muy altas prestaciones o barras de SMA). En esta tesis doctoral se analiza el comportamiento de barras comprimidas, de acero o de SMA en base NiTi, en elementos fabricados con hormigones convencionales, de alta resistencia o de muy altas prestaciones, con o sin fibras en su masa. A tal efecto, se ha ejecutado un programa experimental para estudiar la inestabilidad local de las barras comprimidas (acero y NiTi) en elementos de hormigón. Se han analizado un total de 32 soportes sometidos a una solicitación de flexo-compresión. Se ha propuesto un modelo analítico para determinar la tensión y la longitud crítica de pandeo de barras comprimidas en elementos de hormigón. Este modelo ha sido calibrado con los ensayos experimentales. Se ha realizado un estudio experimental y numérico para analizar el comportamiento de las barras de NiTi como barras aisladas. Se ha propuesto un modelo analítico para calcular la relación tensión - deformación de barras comprimidas que incluye el efecto del pandeo. Este modelo ha sido verificado tanto con los resultados experimentales como numéricos. Finalmente, se ha propuesto una expresión para el cálculo de la separación máxima de la armadura transversal en función de la tensión límite requerida, tanto para barras de acero como de SMA. Para la definición de dicha tensión se proponen dos criterios: uno basado en tensiones y otro en deformaciones. En el caso de hormigón sin fibras, la expresión propuesta se ha comparado con la normativa actual. / La capacitat de deformació de les estructures depén del comportament de les ròtules plàstiques. Per a millorar dit comportament en estructures de formigó armat, en la literatura tècnica es proposa utilitzar formigó amb fibres d'acer en la seua massa, formigó de molt altes prestacions o substituir en la zona crítica de l'estructura les armadures d'acer per barres d'aliatge amb memòria de forma i superelasticitat (d'ara endavant SMA) entre d'altres solucions. No obstant això, la capacitat de deformació de les ròtules està condicionada pel vinclament de l'armadura comprimida, la qual cosa suposa una disminució dràstica de la capacitat resistent i de la ductilitat. Este fenomen es produeix perquè el recobriment del formigó salta o es degrada, o per una insuficient disposició de l'armadura transversal. En les normatives de disseny es proposen requisits quant al diàmetre i a la separació de l'armadura transversal per assegurar la capacitat resistent o la deformació de la ròtula sense que les armadures comprimides vinclen. No obstant això, estes expressions no son vàlides en elements comprimits fabricats amb nous materiales (formigó amb fibres en la seua massa, formigons de molt altes prestacions o barres de SMA). En esta tesis doctoral s'analitza el comportament de barres comprimides, d'acer o de SMA compost per NiTi, en elements fabricats amb formigons convencionals, d'alta resistència o de molt altes prestacions, amb o sense fibres en la seua massa. A tal efecte, s'ha executat un programa experimental per estudiar la inestabilitat local de les barres comprimides (acer i NiTi) en elements de formigó. S'han analitzat un total de 32 soports somesos a una solicitació de flexo-compressió. S'ha proposat un model analític per determinar la tensió i longitud crítica de vinclament de barres comprimides en elements de formigó. Este model ha sigut calibrat amb els assajos experimentals. S'ha realitzat un estudi experimental i numéric per analitzar el comportament de les barres de NiTi com barres aïllades. S'ha proposat un model analític per calcular la relació tensió-deformació de barres comprimides que inclou l'efecte del vinclament. Este model ha sigut verificat tant amb els resultats experimentals com numérics. Finalment, s'ha proposat una expressió per al càlcul de la separació màxima de l'armadura transversal en funció de la tensió límit requerida., tant per a barres d'acer com de SMA. Per a la definició de dita tensió es proposen dos criteris: uno basat en tensions i l'altre en deformacions. En el cas del formigó amb fibres, l'expressió proposada s'ha comparat amb la normativa actual. / Pereiro Barceló, J. (2017). INESTABILIDAD DE BARRAS COMPRIMIDAS DE ACERO Y DE SMA EN ELEMENTOS DE HORMIGÓN FABRICADOS CON NUEVOS MATERIALES. RECOMENDACIONES DE DISEÑO [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90650

In order to run and manage resource-intensive high-performance applications, large-scale computing and storage platforms have been evolving rapidly in various domains in both academia and industry. The energy expenditure consumed to operate and maintain these cloud computing infrastructures is a major factor to influence the overall profit and efficiency for most cloud service providers. Moreover, considering the mitigation of environmental damage from excessive carbon dioxide emission, the amount of power consumed by enterprise-scale data centers should be constrained for protection of the environment.Generally speaking, there exists a trade-off between power consumption and application performance in large-scale computing systems and how to balance these two factors has become an important topic for researchers and engineers in cloud and HPC communities. Therefore, minimizing the power usage while satisfying the Service Level Agreements have become one of the most desirable objectives in cloud computing research and implementation. Since the fundamental feature of the cloud computing platform is hosting workloads with a variety of characteristics in a consolidated and on-demand manner, it is demanding to explore the inherent relationship between power usage and machine configurations. Subsequently, with an understanding of these inherent relationships, researchers are able to develop effective power management policies to optimize productivity by balancing power usage and system performance. In this dissertation, we develop an autonomic power-aware system management framework for large-scale computer systems. We propose a series of techniques including coarse-grain power profiling, VM power modelling, power-aware resource auto-configuration and full-system power usage simulator. These techniques help us to understand the characteristics of power consumption of various system components. Based on these techniques, we are able to test various job scheduling strategies and develop resource management approaches to enhance the systems' power efficiency.

Providing performance and isolation guarantees for applications running in virtualized datacenter environments requires continuous management of the underlying physical resources. For communication- and I/O-intensive applications running on such platforms, the management methods must adequately deal with the shared use of the high-performance fabrics these applications require. In particular, new classes of latency-sensitive and data-intensive workloads running in virtualized environments rely on emerging fabrics like 40+Gbps Ethernet and InfiniBand/RoCE with support for RDMA, VMM-bypass and hardware-level virtualization (SR-IOV). However, the benefits provided by these technology advances are offset by several management constraints: (i) the inability of the hypervisor to monitor the VMs’ usage of these fabrics can affect the platform’s ability to provide isolation and performance guarantees, (ii) the hypervisor cannot provide fine-grained I/O provisioning or perform management decisions for VMs, thus reducing the degree of consolidation that can be supported on the platforms, and (iii) without such support it is harder to integrate these fabrics into emerging cloud computing platforms and datacenter fabric management solutions. This is made particularly challenging for workloads spanning multiple VMs, utilizing physical resources distributed across multiple server nodes and the interconnection fabric. This thesis addresses the problem of realizing a flexible, dynamic resource management system for virtualized platforms with high performance fabrics. We make the following key contributions: (i) A lightweight monitoring tool, IBMon, integrated with the hypervisor to monitor VMs’ use of RDMA-enabled virtualized interconnects, using memory introspection techniques. (ii) The design and construction of a resource management system that leverages IBMon to provide latency-sensitive applications performance guarantees. This system is built on microeconomic principles of supply and demand and can be deployed on a per-node (Resource Exchange) or a multi-node (Distributed Resource Exchange) basis. Fine-grained resource allocations can be enforced through several mechanisms, including CPU capping or fabric-level congestion control. (iii) Sphinx, a fabric management solution that leverages Resource Exchange to orchestrate network and provide latency proportionality for consolidated workloads, based on user/application-specified policies. (iv) Implementation and experimental evaluation using InfiniBand clusters virtualized with the Xen or KVM hypervisor, managed via the OpenFloodlight SDN controller, and using representative data-intensive and latency-sensitive benchmarks.

The Explicit Finite Element Method is a powerful tool in nonlinear dynamic finite element analysis. Recent major developments in computational devices, in particular, General Purpose Graphical Processing Units (GPGPU's) now make it possible to increase the performance of the explicit FEM. This dissertation investigates existing explicit finite element method algorithms which are then redesigned for GPU's and implemented. The performance of these algorithms is assessed and a new asynchronous variational integrator spatial decomposition (AVISD) algorithm is developed which is flexible and encompasses all other methods and can be tuned based for a user-defined problem and the performance of the user's computer. The mesh-aware performance of the proposed explicit finite element algorithm is studied and verified by implementation. The current research also introduces the use of a Particle Swarm Optimization method to tune the performance of the proposed algorithm automatically given a finite element mesh and the performance characteristics of a user's computer. For this purpose, a time performance model is developed which depends on the finite element mesh and the machine performance. This time performance model is then used as an objective function to minimize the run-time cost. Also, based on the performance model provided in this research and predictions about the changes in GPU's in the near future, the performance of the AVISD method is predicted for future machines. Finally, suggestions and insights based on these results are proposed to help facilitate future explicit FEM development.

Master of Science / Department of Architectural Engineering and Construction Science / Fred L. Hasler / The purpose of this report is to provide an introduction to the new ASHRAE Standard 189.1-2009, Standard for the Design of High-Performance Green Buildings. The report will include an overview of the standard to detail what the purpose, scope and requirements for high-performance buildings will be. The entire standard will be overviewed, but the focus of this paper is in the areas of energy efficiency and building performance. Next, the report will examine further impacts that the standard will have on the building design and construction industry. Chapter 3 includes the impact on other standards, specification writing and coordination of the design and construction teams. A case study of an office building is performed to compare a baseline building meeting ASHRAE Standard 90.1 to a building meeting the minimum standards of ASHRAE Standard 189.1. The case study compares the total annual energy use of the two projects to determine an expected energy savings. Based on this information, recommendations about the new standard will be discussed. Universities and government entities should require ASHRAE Standard 189.1 for new construction projects, to show willingness to provide sustainability in buildings. Finally, conclusions about how the standard will change and impact industry will be addressed. These conclusions will include issues with adopting ASHRAE Standard 189.1 as code as well as discussion on the LEED rating system.

Doctor of Philosophy / Department of Chemistry / Christopher T. Culbertson / High-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) are two well-established analytical separation techniques that are continuously being adapted for performing distinctive separations and analyses of multitudes of complex and/or unique samples. Since their introduction, these techniques have been pivotal in the discovery, analysis, and understanding of a variety of samples and still prove to be key analytical tools for biological investigation. Using these techniques, one can obtain a wide-range of valuable sample information from the hydrophobicity and molecular weights to size and charge distributions. Furthermore, these techniques allow for sample analysis, purification, and collection for additional sample analysis, such as mass spectrometry analysis. My doctoral dissertation encompasses the full scope of these two techniques and novel approaches for the investigation of distinct, relevant samples. Described herein is the fabrication of glass microfluidic devices used for CE and their diversity for numerous investigations. Chapter 2 shows that the resolution of the photomasks used in microchip fabrication does not alter the separation efficiency of the devices, as the separations remain diffusion-limited. Using an in-house built capillary electrophoresis system, wheat proteins were separated more than 25% faster than previously reported in literature, and the electropherograms used for sample varietal identification. The fabrication of a robust, portable CE system capable of performing biological analysis in microgravity and hypergravity environments is also discussed. The need for and features necessary to achieve a reliable, robust, automated system is further described in Chapter 4. Isolation and analysis of the pea aphid (Acyrthosiphon pisum) salivary secretions was completed for the first time using HPLC. By altering the aphid environment and the sample treatment parameters, sample concentrations were increased above the limit of detection. Coupled with mass spectrometry, identification of pea aphid salivary proteins such as exopeptidase, angiotensin converting enzyme, and Buchnera proteins has been achieved. Finally, a simplified contact conductivity detection system for the detection of jurkat cells was developed that surpasses current, complex optical systems. The experiments described in this dissertation demonstrate novel approaches for the preparation, separation, analysis, and identification of a wide variety of common, and uncommon, samples.

Mobile devices are often expected to perform computational tasks that may be beyond their processing or battery capability. Cloud computing techniques have been proposed as a means to offload a mobile device's computation to more powerful resources. In this thesis, we consider the case where powerful computing resources are made available by utilizing vehicles. These vehicles can be repositioned in real time to receive computational tasks from user-carried devices. They can be either equipped with rugged high-performance computers to provide both computation and communication service, or they can be simple message ferries that facilitate communication with a more powerful computing resource. These scenarios find application in challenged environments and may be used in a military or disaster relief settings. It is further enabled by increasing feasibility of (i) constructing a Mobile High Performance Computer (MHPC) using rugged computer hardware with form factors that can be deployed in vehicles and (ii) Message Ferries (MF) that provide communication service in disruption tolerant networks. By analogy to prior work on message ferries and data mules, one can refer to the use of our first schema, MHPCs, as computational ferrying. After illustrating and motivating the computational ferrying concept, we turn our attention into the challenges facing such a deployment. These include the well known challenges of operating an opportunistic and intermittently connected network using message ferries -- such as devising an efficient mobility plan for MHPCs and developing techniques for proximity awareness. In this thesis, first we propose an architecture for the system components to be deployed on the mobile devices and the MHPCs. We then focus on defining and solving the MHPC movement scheduling problem with sufficient generality to describe a number of plausible deployment scenarios. After thorough examination of the MHPC concepts, we propose a scheme in which MHPCs are downgraded to be simple MFs that instead provide communication to a stationary HPC with powerful computing resources. Similar to the MPHCs, we provide a framework for this problem and then describe heuristics to solve it. We conduct a number of experiments that provide an understanding of how the performance of the system using MHPCs or MFs is affected by various parameters. We also provide a thorough comparison of the system in the dimensions of Computation on the Move and Controlling the Mobility.

Most commercially available valves are able to produce a large flow rate or a fast response, but are incapable of producing both simultaneously. Commercially available valves that can achieve both are expensive as they require multiple stages of actuation and piloting pressures to deliver large flow rates quickly, preventing them from being broadly used in fluid power applications. This work investigates the design of an Energy Coupling Actuated Valve (ECAV) that is capable of solving this trade-off between large flow and fast switching times through the use of an innovative, high performance actuation system. The ECAV is a new development in valve technology in the area of hydraulic, high speed, proportional and digital on/off valves. High speed actuation is produced through the intermittent coupling of a kinetic energy source with a translational poppet or spool. This coupling process occurs through the use of magnetorheological fluid and a controlled magnetic flux through the fluid in the energy coupler. The ECAV has several design advantages including proportional force control and a large (7mm) stroke capability. Early results predict a nominal flow rate of 100 L/min at a 5 bar pressure drop can be achieved with a 3 ms on/off response time.

The stagnant performance of single core processors, increasing size of data sets, and variety of structure in information has made the domain of parallel and high-performance computing especially crucial. Graphics Processing Units (GPUs) have recently become an exciting alternative to traditional CPU architectures for applications in this domain. Although GPUs are designed for rendering graphics, research has found that the GPU architecture is well-suited to algorithms that search and analyze unstructured, graph-based data, offering up to an order of magnitude greater memory bandwidth over their CPU counterparts. This thesis focuses on GPU graph analysis from the perspective that algorithms should be efficient on as many classes of graphs as possible, rather than being specialized to a specific class, such as social networks or road networks. Using betweenness centrality, a popular analytic used to find prominent entities of a network, as a motivating example, we show how parallelism, distributed computing, hybrid and on-line algorithms, and dynamic algorithms can all contribute to substantial improvements in the performance and energy-efficiency of these computations. We further generalize this approach and provide an abstraction that can be applied to a whole class of graph algorithms that require many simultaneous breadth-first searches. Finally, to show that our findings can be applied in real-world scenarios, we apply these techniques to the problem of verifying that a multiprocessor complies with its memory consistency model.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Complex polymers are defined by their distributive properties with respect to molecular weight, chemical composition, functionality and molecular topology. As a result, polymer properties are very frequently determined not only by one of these entities but by the correlation of two or more distributions. Aliphatic polyesters are industrially implemented in high performance coatings, paints and varnishes. However, it is typically difficult to correlate the resulting properties with the synthesis parameters as these polymers vary in reactivity and application properties. Copolyester synthesis by direct polyesterification is often assumed to produce randomized products due to the mechanisms involved in stepwise polymerization. The formation of cyclic products by intramolecular reactions of hydroxyl (OH) and carboxylic (COOH) functional groups, sidereactions such as transesterification, alcoholysis, and ester-ester interchange allow even further randomization, enabling a highly complex system. Therefore, in addition to molecular weight distribution, polyesters exhibit chemical composition, functionality type as well as branching distributions, classifying them as complex polymeric systems. The different methods of polymer chromatography in combination with sophisticated spectrometry techniques are useful tools for enabling the full description of the molecular heterogeneity of these complex polyesters. The present study entails method development of different modes of chromatography and mass spectrometry along with their combination, to facilitate the analysis of the various distributions of two model polyester systems, phthalic and maleic anhydride, respectively, in combination with propylene glycol. Gradient HPLC analysis enabled an oligomeric separation based on chemical composition of the respective anhydride/propylene glycol samples. Its off-line coupling to MALDITOF MS and ESI-QTOF MS revealed the presence of several distributions of varying endgroup functionality type and molecular weight distributions at different intervals throughout the polymerization. In addition, online gradient HPLC x size exclusion chromatography (2D-LC) was conducted to obtain the dual chemical composition-molecular weight (CCD-MWD) distribution. The combination of the different coupling techniques provided the opportunity to a more in-depth analysis of the structure-property relationships. / AFRIKAANSE OPSOMMING: Komplekse polimere word gedefinieer deur hul verdelings eienskappe ten opsigte van molekulêre massa, chemiese samestelling, funksionaliteit en molekulêre topologie. Gevolglik, word hul eienskappe dikwels bepaal deur nie net een van hierdie entiteite nie, maar ‘n korrelasie van twee of meer verdelings. Alifatiese poliësters word industrieel geϊmplimenteer in hoë werkverrigting bestrykings, verwe en politoere, dog is dit tipies moeilik om die uiteinde eienskappe met die verwante sintese parameters te korrelleer, aangesien die polimere varieer in reaktiviteit en toepassingseienskappe. Ko-poliëster sintese vanaf direkte poliësterivering word dikwels aanvaar om willekeurige produkte op te lewer as gevolg van die meganismes wat betrokke is tydens trapgroei polimerisasie. Die produsering van sikliese produkte weens intra-molekulêre reaksies van hidroksiel(OH) en karboksiel (COOH) verwante funksionele groepe, newereaksies soos transverestering, alkoholise en ester-ester verwisseling, het verdere ewekansigmaking tot gevolg wat ‘n hoog gekomplekseerde sisteem tot gevolg het. Benewens die molekulere massa verdeling, vertoon poliësters dus chemiese samestelling, funksionaliteit tipe so wel as vertakkings verdeling wat hul as komplekse polimeer sisteme klassifiseer. Die verskillende metodes van polimeer chromatografie in kombinasie met gesofistikeerde spektrometriese tegnieke dien as nuttige bronne vir die volledige beskrywing wat betref die molekulêre heterogeniteit van komplekse poliesters. Die huidige studie stel metode ontwikkeling van verskillende modus van chromatografie, massa spektrometrie sowel as hul aaneenvoeging bekend, om die die verskillende verdelings van twee model poliester sisteme, ftaal- en maleϊensuuranhidried onderskeidelik in kombinasie met propileenglikol, suksesvol te analiseer. Gradiënt hoë-druk vloeistof chromatografie (HPLC) analise het ‘n oligomeriese skeiding, gebaseer op die chemiese samestelling van die verskeie anhidried /propileenglikol monsters, opgelewer. Die nie-gekoppelde skakeling met matriks-assisteerdelaser/ desorpsie-ionisasie tyd-van-vlug (MALDI-TOF) en elektron-sproei-ionisasie kwadrupool-tyd-van-vlug (ESI-QTOF) massa spektrometrie het die teenwoordigheid van verskeie verdelings van varieërende endgroep funksionaliteit tipe en molekulêre verdelings by verskillende intervalle tydens die polimerisasie aan die lig gebring. Gekoppelde skakeling van gradient HPLC en grootte uitsluitings chromatografie is ook uitgevoer om die tweedelige chemiese samestelling-molekulere massa verdeling te bepaal. Aaneenvoeging van die verskeie skakelings tegnieke het die geleentheid gebied om ‘n deeglike studie van die struktuureienskappe verhoudinge suksesvol uit te voer.