Energy aware software for many-core systems

Many-core systems provide a great potential in application performance with the massively parallel structure. Such systems are currently being integrated into most parts of daily life from high-end server farms to desktop systems, laptops and mobile devices. Yet, these systems are facing increasing challenges such as high temperature causing physical damage, high electrical bills both for servers and individual users, unpleasant noise levels due to active cooling and unrealistic battery drainage in mobile devices; factors caused directly by poor energy efficiency. Power management has traditionally been an area of research providing hardware solutions or runtime power management in the operating system in form of frequency governors. Energy awareness in application software is currently non-existent. This means that applications are not involved in the power management decisions, nor does any interface between the applications and the runtime system to provide such facilities exist. Power management in the operating system is therefore performed purely based on indirect implications of software execution, usually referred to as the workload. It often results in over-allocation of resources, hence power waste. This thesis discusses power management strategies in many-core systems in the form of increasing application software awareness of energy efficiency. The presented approach allows meta-data descriptions in the applications and is manifested in two design recommendations: 1) Energy-aware mapping 2) Energy-aware execution which allow the applications to directly influence the power management decisions. The recommendations eliminate over-allocation of resources and increase the energy efficiency of the computing system. Both recommendations are fully supported in a provided interface in combination with a novel power management runtime system called Bricktop. The work presented in this thesis allows both new- and legacy software to execute with the most energy efficient mapping on a many-core CPU and with the most energy efficient performance level. A set of case study examples demonstrate realworld energy savings in a wide range of applications without performance degradation.

Design and Simulation of High-Speed Rotating Electrical Machinery

Global energy consumption has been increasing yearly and a big portion of it is used in rotating electrical machineries. It is clear that in these machines energy should be used efficiently. In this dissertation the aim is to improve the design process of high-speed electrical machines especially from the mechanical engineering perspective in order to achieve more reliable and efficient machines. The design process of high-speed machines is challenging due to high demands and several interactions between different engineering disciplines such as mechanical, electrical and energy engineering. A multidisciplinary design flow chart for a specific type of high-speed machine in which computer simulation is utilized is proposed. In addition to utilizing simulation parallel with the design process, two simulation studies are presented. The first is used to find the limits of two ball bearing models. The second is used to study the improvement of machine load capacity in a compressor application to exceed the limits of current machinery. The proposed flow chart and simulation studies show clearly that improvements in the high-speed machinery design process can be achieved. Engineers designing in high-speed machines can utilize the flow chart and simulation results as a guideline during the design phase to achieve more reliable and efficient machines that use energy efficiently in required different operation conditions.

Evaluation of the main energy scenarios for the global energy transition

Energy scenarios are used as a tool to examine credible future states and pathways. The one who constructs a scenario defines the framework in which the possible outcomes exist. The credibility of a scenario depends on its compatibility with real world experiences, and on how well the general information of the study, methodology, and originality and processing of data are disclosed. In the thesis, selected global energy scenarios’ transparency and desirability from the society’s point of view were evaluated based on literature derived criteria. The global energy transition consists of changes to social conventions and economic development in addition to technological development. Energy solutions are economic and ethical choices due to far-reaching impacts of energy decision-making. Currently the global energy system is mostly based on fossil fuels, which is unsustainable over the long-term due to various reasons: negative climate change impacts, negative health impacts, depletion of fossil fuel reserves, resource-use conflicts with water management and food supply, loss of biodiversity, challenge to preserve ecosystems and resources for future generations, and inability of fossil fuels to provide universal access to modern energy services. Nuclear power and carbon capture and storage cannot be regarded as sustainable energy solutions due to their inherent risks and required long-term storage. The energy transition is driven by a growing energy demand, decreasing costs of renewables, modularity and scalability of renewable technologies, macroeconomic benefits of using renewables, investors’ risk awareness, renewable energy related attractive business opportunities, almost even distribution of solar and wind resources on the planet, growing awareness of the planet’s environmental status, environmental movements and tougher environmental legislation. Many of the investigated scenarios identified solar and wind power as a backbone for future energy systems. The scenarios, in which the solar and wind potentials were deployed in largest scale, met best the set out sustainability criteria. In future research, energy scenarios’ transparency can be improved by better disclosure on who has ordered the study, clarifying the funding, clearly referencing to used sources and indicating processed data, and by exploring how variations in cost assumptions and deployment of technologies influence on the outcomes of the study.

Standardized electrical tests for electrical equipment in road vehicles Case: Visedo Oy PowerMASTER M-frame

Electrical road vehicles were common at the begin of the 20th century but internal combustion engines took a victory from electrical motors in road vehicles. The acknowledgement of the environment, and the price and the availability of the crude oil are reasons for the comeback of the electrical vehicles. Advancement in industrial technology and political atmosphere in EU as the directive 20--20--20, which consists of reducing fossil emission, increasing renewable energy and increasing the energy efficiency, have made the electrification popular again. In this thesis tests based on standard ISO 16750--2 electrical loads for electrical equipment in road vehicles are made for Visedo Oy's PowerMASTER M-frame power electronics device. This device is designed for mainly drive trains in mobile work machines and marine vessels but can be used in other application in its power range which also includes road vehicles. The functionality of the device is tested with preliminary tests which act as a framework for the tests based on standards.