In recent years, with the rapid development of electric and electronic technology, the All-Electric Aircraft (AEA) concept has attracted more and more attention, which only utilizes the electric power instead of conventional hydraulic and pneumatic power to supply all the airframe systems. To meet the power requirements under various flight stages and operating conditions, the AEA approach has resulted in the current aircraft electrical power generation capacity up to 1.6 MW. To satisfy the power quality and stability requirements, the advanced power electronic interfaces and more efficient power distribution systems must be investigated. Moreover, with the purpose of taking the full advantages of available electrical power, novel dynamic power distribution management research and design for an AEA must be carried out. The main objective of this thesis is to investigate and develop a methodology of more efficient power distribution management with the purpose of minimizing the rated power generating capacity and the mass of the electrical power system (EPS) including the power generation system and the power distribution system in an AEA. It is important to analyse and compare the subsistent electrical power distribution management approaches in current aircraft. Therefore the electrical power systems of A320 and B777, especially the power management system, will be discussed in this thesis. Most importantly the baseline aircraft, the Flying Crane is the outcome of the group design project. The whole project began in March 2008, and ended in September 2010, including three stages: conceptual design, preliminary design and detailed design. The dynamic power distribution management research is based on the power distribution system of the Flying Crane. The main task of the investigation is to analyse and manage the power usage among and inside typical airframe systems by using dynamic power distribution management method. The characteristics and operation process of these systems will be investigated in detail and thoroughly. By using the method of dynamic power distribution management, all the electrical consumers and sub-systems powered by electricity are managed effectively. The performance of an aircraft can be improved by reducing the peak load requirement on board. Furthermore, the electrical system architecture, distributed power distribution system and the dynamic power distribution management system for AEA are presented. Finally, the mass of the whole electrical power system is estimated and analysed carefully.

There has been a constant need for low power techniques to achieve high performance at the lowest possible power dissipation. Lots of works have been done to achieve this target. These works have focused on the different aspects of power reduction. One of these aspects of power saving is Dynamic power reduction. This thesis work is focused on this aspect of power saving by reducing the unnecessary transitioning in the circuit. To achieve this, new method called data gating, is proposed here which stops unnecessary toggling in the circuit using different forms of gating mechanisms. This thesis is organized as follows; first chapter is about the low power design of CMOS circuits. That chapter covers the sources of power dissipation in ICs as well as the techniques that have been used to minimize the power consumption. Second chapter talks more about dynamic power consumption. Techniques used for reducing dynamic power consumption through reduction in switching activities are mentioned in that chapter. Also the new technique, Data Gating, to reduce dynamic power is proposed in second chapter. Third chapter talks about simulation setup, tools used for simulation. Results obtained from different simulations are presented in that chapter. Fourth Chapter is about the analysis of simulation results. It also outlines some possible limitations of the proposed method as well as certain points that need to be considered before applying new technique. Fifth and final chapter summarizes the conclusion and possible future work that can be done to enhance the proposed technique, Data Gating. / text

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Long Term Evolution (LTE) is enormously adopted by several mobile operators and has been introduced as a solution to fulfil ever-growing Users (UEs) data requirements in cellular networks. Enlarged data demands engage resource blocks over prolong time interval thus results into more dynamic power consumption at downlink in Basestation. Therefore, realisation of UEs requests come at the cost of increased power consumption which directly affects operator operational expenditures. Moreover, it also contributes in increased CO2 emissions thus leading towards Global Warming. According to research, Global Information and Communication Technology (ICT) systems consume approximately 1200 to 1800 Terawatts per hour of electricity annually. Importantly mobile communication industry is accountable for more than one third of this power consumption in ICT due to increased data requirements, number of UEs and coverage area. Applying these values to global warming, telecommunication is responsible for 0.3 to 0.4 percent of worldwide CO2 emissions. Moreover, user data volume is expected to increase by a factor of 10 every five years which results in 16 to 20 percent increase in associated energy consumption which directly effects our environment by enlarged global warming. This research work focuses on the importance of energy saving in LTE and initially propose bandwidth expansion based energy saving scheme which combines two resource blocks together to form single super RB, thereby resulting in reduced Physical Downlink Control Channel Overhead (PDCCH). Thus, decreased PDCCH overhead helps in reduced dynamic power consumption up to 28 percent. Subsequently, novel reduced early handover (REHO) based idea is proposed and combined with bandwidth expansion to form enhanced energy ii saving scheme. System level simulations are performed to investigate the performance of REHO scheme; it was found that reduced early handover provided around 35% improved energy saving while compared to LTE standard in 3rd Generation Partnership Project (3GPP) based scenario. Since there is a direct relationship between energy consumption, CO2 emissions and vendors operational expenditure (OPEX); due to reduced power consumption and increased energy efficiency, REHO subsequently proven to be a step towards greener communication with lesser CO2 footprint and reduced operational expenditure values. The main idea of REHO lies in the fact that it initiate handovers earlier and turn off freed resource blocks as compare to LTE standard. Therefore, the time difference (Transmission Time Intervals) between REHO based early handover and LTE standard handover is a key component for energy saving achieved, which is estimated through axiom of Euclidean geometry. Moreover, overall system efficiency is investigated through the analysis of numerous performance related parameters in REHO and LTE standard. This led to a key finding being made to guide the vendors about the choice of energy saving in relation to radio link failure and other important parameters.

We present an energy conscious location-aware computing system that provides relevant information about the users current location. The location-aware computing system is initialized with a map (in the form of a graph) as well as audio files associated with several locations in the map. The system consists of: GPS receiver module, Serial port, Compact flash module, Stereo codec, Power manager module implementing three sub modules namely, GPS-to-real-world position conversion module (implements algorithm to convert GPS co-ordinates to graph nodes), Nearest-location-search module (implements modified Dijkstras algorithm), and User speed estimation module. The location-aware computing system receives the GPS co-ordinates for the current location from GPS receiver through the serial port. The system converts the GPS co-ordinates to map co-ordinates stored in the Compact Flash card. If the current location matches the landmarks of interest in the site, then the relevant audio details of the current location is played out to the user. The power manager sets the GPS co-ordinates update frequency to avoid keeping the system component on throughout the entire course of travel. The power manager implements an algorithm that works as follows: at any given location, the algorithm predicts the user speed by exponential average approach. The attenuation factor of this approach can be varied to account for the user speed history. The estimated speed is used to predict the time (say T) required to reach the next nearest location determined by Nearest-location-search module implementing modified Dijkstras algorithm. The subsystems are shut-down or switched to low-power mode for time T. After time T, the system will wake up and re-execute the algorithm.

In the present day, Ad Hoc wireless networks are quite convenient in a local area. But hidden terminal problems and exposed terminal problems exits in Ad Hoc networks. So how to avoid these problems and add channel bandwidth utilization efficiently in MAC (Medium Access Control) layer is a very critical topic. A number of MAC protocols have been presented to overcome these drawbacks, such as RTS / CTS ¡V based and busy tone ¡V based protocol. In this paper, we proposed a dynamic power control scheme, Adjustable Power Control Protocol (APC). APC is based on the concept of power level with broadcasted message. The basic idea is sender should not interfere with other hosts¡¦ going transmissions. Sender would use a suitable power level to send its data so as to overcome above problems. Our simulations show that the channel utilizations of APC is indeed increased in the same time.

Energy saving, in battery operated wireless sensor networks, for the purpose of increasing the node and network lifetime, has gained substantial importance. This research was conducted with the objective of reducing the power consumption of the MICA2 sensors. The objective was pursued by manipulating the MAC layer, and by introducing a dynamic transmission power control algorithm. A new simulation tool was developed in order to reduce the complexity related to the design and testing of the transmission power control algorithm. The power control algorithm was also developed in the NesC language for the MICA2 sensors. In addition,several modifications were introduced to the original MAC protocol. Data, derived from both simulations and experiments, demonstrated that a significant reduction in energy expenditure was achieved, for the MICA2 sensors. In addition,the data revealed that the network lifetime was extended. This research dramatically illustrated the energy saving potential of the application of transmission power control procedures in wireless sensor networks.

This thesis introduces performance and power optimization techniques for caches. Our optimization techniques target both conventional caches, which are implemented using six-transistor (6T) cells, and highly reliable caches implemented using eight-transistor (8T) cells. In 6T cell caches, we enhance leakage power dissipation by adapting a previous proposed technique, Drowsy Cache, according to the application behavior. We show that spatial locality in embedded applications is low and Drowsy Cache misses a significant leakage power saving opportunities. By taking a finer granularity approach, we achieve a significant leakage power reduction with minimal performance overhead. Although 6T cell caches are commonly used, we show that they are not proper choice for future designs due to poor stability. We investigate 8T cells as alternative reliable designs for implementing caches. However, Column Selection Issue limits efficiency of 8T cells during write operations. Previous solution, Read-Modify-Write (RMW), addressed column selection issue by requiring a read operation before each write operation, imposing significant overhead on performance, cache traffic, and power. We observe that a significant share of cache accesses in RMW is either redundant or unnecessary, consequently can be avoided without compromising program execution consistency. Based on our observations, we propose two techniques which exploit a buffering mechanism to detect and filter out unnecessary and redundant cache accesses. Our simulation results show that our techniques improve performance and cache traffic effectively in 8T cell caches. Furthermore, we propose a novel dual threshold 8T cell which reduces leakage power significantly with negligible impact on performance. Our proposed cell also improves stability and robustness to process variations compared to the conventional 8T cells. / Graduate / 0544 / farahani.mostafa@gmail.com

This thesis presents a novel self-powered infrastructural traffic monitoring approach that estimates traffic information by combining three detection techniques. The traffic information can be obtained from the presented approach includes vehicle counts, speed estimation and vehicle classification based on size. Two categories of sensors are used including IR Lidar and IR camera. With the two sensors, three detection techniques are used: Time of Flight (ToF) based, vision based and Laser spot flow based. Each technique outputs observations about vehicle location at different time step. By fusing the three observations in the framework of Kalman filter, vehicle location is estimated, based on which other concerned traffic information including vehicle counts, speed and class is obtained. In this process, high reliability is achieved by combing the strength of each techniques. To achieve self-powering, a dynamic power management strategy is developed to reduce system total energy cost and optimize power supply in traffic monitoring based on traffic pattern recognition. The power manager attempts to adjust the power supply by reconfiguring system setup according to its estimation about current traffic condition. A system prototype has been built and multiple field experiments and simulations were conducted to demonstrate traffic monitoring accuracy and power reduction efficacy. / Master of Science

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