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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Energy Accounting and Optimization for Mobile Systems

Dong, Mian 16 September 2013 (has links)
Energy accounting determines how much a software process contributes to the total system energy consumption. It is the foundation for evaluating software and has been widely used by operating system based energy management. While various energy accounting policies have been tried, there is no known way to evaluate them directly simply because it is hard to track every hardware use by software in a heterogeneous multicore system like modern smartphones and tablets. This work provides the ground truth for energy accounting based on multi-player game theory and offers the first evaluation of existing energy accounting policies, revealing their important flaws. The proposed ground truth is based on Shapley value, a single value solution to multi-player games of which four axiomatic properties are natural and self-evident to energy accounting. This work further provides a utility optimization formulation of energy management and shows, surprisingly, that energy accounting does not matter for existing energy management solutions that control the energy use of a process by giving it an energy budget, or budget based energy management (BEM). This work shows an optimal energy management (OEM) framework can always outperform BEM. While OEM does not require any form of energy accounting, it is related to Shapley value in that both require the system energy consumption for all possible combination of processes under question. This work reports a prototype implementation of both Shapley value-based energy accounting and OEM based scheduling. Using this prototype and smartphone workload, this work experimentally demonstrates how erroneous existing energy accounting policies can be, show that existing BEM solutions are unnecessarily complicated yet underperforming by 20% compared to OEM.
2

Energy Modelling and Fairness for Efficient Mobile Communication

Vergara Alonso, Ekhiotz Jon January 2016 (has links)
Energy consumption and its management have been clearly identified as a challenge in computing and communication system design, where energy economy is obviously of paramount importance for battery powered devices. This thesis addresses the energy efficiency of mobile communication at the user end in the context of cellular networks. We argue that energy efficiency starts by energy awareness and propose EnergyBox, a parametrised tool that enables accurate and repeatable energy quantification at the user end using real data traffic traces as input. EnergyBox offers an abstraction of the underlying states for operation of the wireless interfaces and allows to estimate the energy consumption for different operator settings and device characteristics. The tool is used throughout the thesis to quantify and reveal inefficient data communication patterns of widely used mobile applications. We consider two different perspectives in the search of energy-efficient solutions. From the application perspective, we show that systematically quantifying the energy consumption of design choices (e.g., communication patterns, protocols, and data formats) contributes to a significantly smaller energy footprint. From the system perspective, we devise a cross-layer solution that schedules packet transmissions based on the knowledge of the network parameters that impact the energy consumption of the handset. These attempts show that application level decisions require a better understanding of possible energy apportionment policies at system level. Finally, we study the generic problem of determining the contribution of an entity (e.g., application) to the total energy consumption of a given system (e.g., mobile device). We compare the state-of-the-art policies in terms of fairness leveraging cooperative game theory and analyse their required information and computational complexity. We show that providing incentives to reduce the total energy consumption of the system (as part of fairness) is tightly coupled to the policy selection. Our study provides guidelines to select an appropriate policy depending on the characteristics of the system.
3

Energy Audit and Accounting for Riksbyggen Fastighetsservice, Gävle

Liu, Yuanyuan, Shen, Yang January 2009 (has links)
<p>Riksbyggen Fastighetsservice is a company whose businesses cope with building construction and related services. The local office of Riksbyggen Fastighetsservice in Gävle has been studied in this project. The local office locates in Näringen 20:4, which was constructed in 1989.</p><p> </p><p>The aim of this project is to make a diagnosis of the current situation; find out the most applicable way of optimizing the operation of the facility in order to reduce the energy consumption, to study costs and possible savings and provide assistance with future energy management.   </p><p> </p><p>Firstly, a study of Energy Balance was conducted. The transmission losses was 57761 KWh; mechanical ventilation losses 3855 KWh; hot tap water heat losses 9579 KWh; natural transmission and infiltration 6897 KWh. On the other hand, heat gain from internal heat was 12707 KWh; solar radiation 8521 KWh; and supply heat 56806 KWh.</p><p> </p><p>Secondly, the energy costs have been checked out. 29655 KWh of electricity was consumed in 2008. 5948 KWh was used by 20 fuses electricity and 23707 KWh was for 25 fuses. Lighting, electrical equipment and machine composed the electricity consumption. Lighting consumes 13278 KWh; equipment consumes 6452 KWh; and machine consumes 9925 KWh. Lighting electricity was composed by office lighting and workshop lighting with 4798 KWh and 8480 KWh respectively.</p><p> </p><p>Electricity cost is very complicated and flexible in Sweden according to effect and consumption. The total cost of electricity consists of electricity commerce fee and electricity transmission net. Electricity commerce fee includes annual fixed fee, electricity fee, energy certificate and tax. Electricity transmission fee includes annual fixed transmission fee, grid fee and tax. Tax plays vital important role which results in huge total cost. The local office spent 43356 kr on electricity in 2008. 4798 kr was spent on office lighting, and 8480 kr was spent on workshop lighting.</p><p> </p><p>On the other hand district heating fee is composed by annual fixed fee, effect fee, energy fee and tax. The local office spent 37142 kr on 56.806 MWh of district heating in 2008. Thus, the local office purchased 86461 KWh of energies and spent 80498 kr in total in 2008.</p><p> </p><p>Thirdly, to assist its energy traces and management, three tables were designed. One table is for annual energy consumption and cost in each month with all information of sub-terms on costs. One table is for annual electricity consumption for each electrical equipment and cost in accordance. Another table is for district heating consumption and cost. </p><p> </p><p>At last, energy saving possibilities was explored. One way is applying improvements or maintenance of the office construction. The result of Energy Balance shows that transmission losses were 57761 KWh which occupies 74% of the total losses, and it is the biggest bite. As the office was constructed in 1989, if improvements and maintenance can be applied to the insulation of floor, roof and walls, or change the windows, the heat losses can be reduced.</p><p> </p><p>However, the other solution might be much more applicable and financial sound. Just go to Clas Ohlson to buy LED 1 W and 3 W lamps to replace the current bulbs. Spending 3009 kr to buy 51 LED incandescent bulbs of 1W effect, and 3576 kr on 24 LED fluorescent of 3W effect, will save 12057 kr every year. The lighting electricity consumption will be reduced from 13278 KWh / year to 264 KWh / year. Instead of spending 16017 kr on lighting, 98% will be reduced, and only 318 kr will be paid. Moreover, the payback is really nice, only 0.42 year. Action! The sooner the better! 20% of energy cost will be saved!</p>
4

Energy Audit and Accounting for Riksbyggen Fastighetsservice, Gävle

Liu, Yuanyuan, Shen, Yang January 2009 (has links)
Riksbyggen Fastighetsservice is a company whose businesses cope with building construction and related services. The local office of Riksbyggen Fastighetsservice in Gävle has been studied in this project. The local office locates in Näringen 20:4, which was constructed in 1989.   The aim of this project is to make a diagnosis of the current situation; find out the most applicable way of optimizing the operation of the facility in order to reduce the energy consumption, to study costs and possible savings and provide assistance with future energy management.      Firstly, a study of Energy Balance was conducted. The transmission losses was 57761 KWh; mechanical ventilation losses 3855 KWh; hot tap water heat losses 9579 KWh; natural transmission and infiltration 6897 KWh. On the other hand, heat gain from internal heat was 12707 KWh; solar radiation 8521 KWh; and supply heat 56806 KWh.   Secondly, the energy costs have been checked out. 29655 KWh of electricity was consumed in 2008. 5948 KWh was used by 20 fuses electricity and 23707 KWh was for 25 fuses. Lighting, electrical equipment and machine composed the electricity consumption. Lighting consumes 13278 KWh; equipment consumes 6452 KWh; and machine consumes 9925 KWh. Lighting electricity was composed by office lighting and workshop lighting with 4798 KWh and 8480 KWh respectively.   Electricity cost is very complicated and flexible in Sweden according to effect and consumption. The total cost of electricity consists of electricity commerce fee and electricity transmission net. Electricity commerce fee includes annual fixed fee, electricity fee, energy certificate and tax. Electricity transmission fee includes annual fixed transmission fee, grid fee and tax. Tax plays vital important role which results in huge total cost. The local office spent 43356 kr on electricity in 2008. 4798 kr was spent on office lighting, and 8480 kr was spent on workshop lighting.   On the other hand district heating fee is composed by annual fixed fee, effect fee, energy fee and tax. The local office spent 37142 kr on 56.806 MWh of district heating in 2008. Thus, the local office purchased 86461 KWh of energies and spent 80498 kr in total in 2008.   Thirdly, to assist its energy traces and management, three tables were designed. One table is for annual energy consumption and cost in each month with all information of sub-terms on costs. One table is for annual electricity consumption for each electrical equipment and cost in accordance. Another table is for district heating consumption and cost.    At last, energy saving possibilities was explored. One way is applying improvements or maintenance of the office construction. The result of Energy Balance shows that transmission losses were 57761 KWh which occupies 74% of the total losses, and it is the biggest bite. As the office was constructed in 1989, if improvements and maintenance can be applied to the insulation of floor, roof and walls, or change the windows, the heat losses can be reduced.   However, the other solution might be much more applicable and financial sound. Just go to Clas Ohlson to buy LED 1 W and 3 W lamps to replace the current bulbs. Spending 3009 kr to buy 51 LED incandescent bulbs of 1W effect, and 3576 kr on 24 LED fluorescent of 3W effect, will save 12057 kr every year. The lighting electricity consumption will be reduced from 13278 KWh / year to 264 KWh / year. Instead of spending 16017 kr on lighting, 98% will be reduced, and only 318 kr will be paid. Moreover, the payback is really nice, only 0.42 year. Action! The sooner the better! 20% of energy cost will be saved!

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