A recent surge in the usage of instant messaging (IM) applications on mobile devices has brought the energy efficiency of those applications into the light. We are entering an era where IM applications are changing the message communication on mobile devices, beginning to overtake SMS messages and even phone calls in some cases. Smartphones experience a tremendous increase of data transmissions through wireless interfaces. As illustrated in this work, today's IM applications differ vastly in energy consumption when using the third generation (3G) cellular communication. This thesis focuses on studying the 3G transmission energy footprint of IM applications at the handset level. The energy cost of a common feature used in IM applications that informs that the user is currently typing a response ('typing notify'), is evaluated. The feature is shown to incur a great increase in energy cost compared to the base chat function, ranging from an increase of 43 % to 117 %. The work also proposes a bundle technique that aggregates chat messages over time reducing the energy consumption at the cost of delay for the user. The results show that the bundle technique can save up to 47 % in energy consumption while still keeping the chat function. For the evaluation, conversations collected from a popular IM application are used.

This thesis proposes a methodology for determining sensitivity of building energy consumption of HVAC systems to sensor error. It is based on a series of simulations of a generic building, the model for which is based on several typical input parameters. There are a total of eight scenarios considered in this simulation. The simulation tool was developed based on Excel. The control parameters examined include room temperature, cold deck temperature, hot deck temperature, pump pressure, and fan pressure. All of the parameters considered are varied in order to analyze the sensitivity of building energy consumption to their variation. In this tool, different operation schedules for equipment, occupancy, and lighting are considered. By changing each control parameter, the sensitivity of energy use to sensor error is simulated, a regression model is generated, and the energy consumption change is expressed as a function of sensor error and outside air percentage. Two applications of this methodology are presented in this thesis. One is a SDVAV system and the other is a DDVAV system. The outside air percentage changes the trend of the sensor error curve. After the sensitivity study is discussed, some recommendations regarding the calibration intervals of the sensors are given.

Abstract Steel is the mother of industry, and is also an energy consumption intensive industry. Especially for the rolling mill, the energy consumption in a reheating furnace take a half, so to save energy in a reheating furnace and reduce the energy consumption become the major issue in the future. The reheating furnace used in general process of steel producing can divided into two types-Continuous type and Batch type- through its ability of steel rolling¡Napproach and its demand. In this thesis, our research target is the batch type reheating furnace, we based on theory of heat transfer in a reheating furnace to build a simulation system of reheating furnace and calculate the temperature-time curve of slab and its heat flux. And then we use the thermal balance model to analysis the situation of fuel consumption. According to different operated conditions, we want to discuss the relationships between energy consumption and increasing temperature of slab inside furnace¡Nsoaking degree¡C From analysis result, we can find that fixed the total time in furnace, the longer of heating time is, the lower of average temperature of slab and the higher of temperature difference of discharge slab are. But in the process of increasing temperature, the max temperature difference of slab is lower. Using the exhaust gas to preheat air through the heat exchanger, we can find that when the temperature of preheated air is increasing, the heat loss of exhaust gas and fuel consumption will be lower. When air-fuel ratio is getting higher, the temperature difference in the process of increasing temperature will be getting lower, and it will be higher as the slab soaks. When air-fuel ratio is increasing, the quantity of fuel consumption will increase too. In respect of refractory material, heat loss of furnace and accumulation of heat in refractory material caused by using the refractory cottons is less than using the refractory bricks. Besides that, the different fuel will only affect the quantity of fuel consumption, not increasing temperature of slab and soaking degree.

Thesis (M.A. in National Security Affairs)--Naval Postgraduate School, June 2003. / Thesis advisor(s): Robert E. Looney, Maria Rasmussen. Includes bibliographical references (p. 55-57). Also available online.

Not available / text

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

Due to the fact that construction, maintenance and operation of buildings consume almost 50% of the energy today, architects play a major role in the reduction of energy consumption. The building’s envelope (façades and roof) can have a significant and measurable impact. With regard to overheating and the potential lost of internal heat, transparent parts of the building envelope have a large effect on the building’s energy consumption. Modern, transparent façade systems can fulfill contemporary demands, such as energy conservation, energy production or the degree of visual contact, of sustainable buildings in order to reduce internal heating, cooling, and electrical loads. An analysis of existing shading devices and façade design leads to a comparative analysis of conventional shading devices like horizontal and vertical blinds as well as eggcrate and honeycomb shading structures in a hot-humid climate like Austin, Texas. This study helped evaluating strengths and weaknesses of each device resulting in an optimization process of conventional shading devices. Ultimately, an optimized shading structure has been developed. This project aimed to develop an advanced transparent façade system for a south-oriented commercial façade in Austin, Texas, which fulfills high standards with regard to low energy use, by limiting cooling loads and demands for artificial lighting while avoiding glare and heat losses during the cold season. The optimization has been achieved in providing full shading for a specified period of time throughout the year while providing maximized solar exposure. The shading structure consists out of an array of fixed shading components varying in size and proportion to fulfill criteria like specific views, transparency and aesthetics. The shading structure has been compared to conventional shading devices and analyzed with regard to the reduction of annual solar radiation. The improvement in design and energy consumption contributes to the variety of shading structures for building skins. It is anticipated that the solutions will help to widen the options for aesthetically pleasing, high-performance façades for commercial buildings.

No description available.

No description available.

No description available.