Prompted by the energy crisis in the 1970's, European level fiscal and financial measures encourage energy efficient building design. "Mixed mode" strategies can be employed in buildings with moderate thermal loads, this approach can reduce building energy usage, and by inference, reduce C02 emissions. A mixed mode approach might employ chilled surfaces with displacement ventilation. This thesis investigates the performance and integration of one form of chilled surface design, (a sub-dew point chilled beam), within mixed mode strategies. Sub-dew point chilled beams have a surface temperature that is at or below the zone saturation temperature, this increases the cooling capacity of the chilled beam and consequently produces a latent heat transfer addition due to condensation mass transfer. This thesis describes the sensible and latent modelling approach which models the zone, sub-dew point chilled beam and mixed mode strategy thermal plant response to external disturbances. The thesis describes the use of an Enclosure Comfort Performance Indicator that acts as the objective function for the optimization of the mixed mode strategies with and without the integration of the sub-dew point chilled beam. The implementation of the Complex method for finding the operational optimums of the mixed mode strategy is described, and its effectiveness at finding the optimum solution evaluated. Normalised energy, cost and comfort performance indicators are used to assess the overall performance and integration of the sub-dew point chilled beam for different mixed mode strategies, for the ambient test conditions and for different thermal weights of building construction.

Thesis (Ph. D.)--University of Chicago Graduate School of Business, August 1999. / Includes bibliographical references. Also available on the Internet.

We present PTIME language-preserving techniques for the reduction of non-deterministic tree automata, both for the case of finite trees and for infinite trees. Our techniques are based on new transition removing and state merging results, which rely on binary relations that compare the downward and upward behaviours of states in the automaton. We use downward/upward simulation preorders and the more general but EXPTIME-complete trace inclusion relations, for which we introduce good under-approximations computable in polynomial time. We provide a complete picture of combinations of downward and upward simulation/trace inclusions which can be used in our reduction techniques. We define an algorithm that puts together all the reduction results found for finite trees, and implemented it under the name minotaut, a tool built on top of the well-known tree automata library libvata. We tested minotaut on large collections of automata from program verification provenience, as well as on different classes of randomly generated automata. Our algorithm yields substantially smaller and sparser automata than all previously known reduction techniques, and it is still fast enough to handle large instances. Taking reduction of automata on finite trees one step further, we then introduce saturation, a technique that consists of adding new transitions to an automaton while preserving its language. We implemented this technique on minotaut and we show how it can make subsequent state-merge and transition-removal operations more effective. Thus we obtain a PTIME algorithm that reduces the number of states of tree automata even more than before. Additionally, we explore how minotaut alone can play an important role when performing hard operations like complementation, allowing to obtain smaller complement automata and at lower computation times overall. We then show how saturation can extend this contribution even further. An overview of the tool, highlighting some of its implementation features, is presented as well.

Recently an efficient multicasting protocol has been reported which uses a concept known as pseudo diameter to reduce the number of duplicate packets generated during multicasting in wide area networks (WANs). This work is superior to the Distance Vector Multicast Routing protocols (DVMRP) from the viewpoint of better bandwidth utilization. In this thesis security aspect of the above mentioned multicast protocol has been considered. Asymmetric key cryptography concept has been used effectively to design the protocol.

This work is concerned with the analysis of industrial energy use for the purposes of reducing that use to a minimum within the constraints imposed by the existing plant. The work is divided into two parts. Firstly, a general analysis of the energy used in an industrial plant is made for the year 1986. Based on monthly records of energy consumption and environmental parameters, it is primarily intended to heighten management awareness of energy flows and the relative contributions from each energy type towards the total annual consumption and cost. It is performed using a suite of interactive linked computer programs and the data is reduced to a graphical form for presentation in a report. The analysis is a first approximation, assuming steady state conditions with many parameters time and space averaged, but is justified by the findings that monetary savings approaching 5% of the annual energy bill could be made with changes to operational procedures alone. As a result of this work, it was revealed that the boiler-house supplying the majority of the plant with high pressure hot water for process and space heating requirements used more than half of the total annual energy requirements and that potential energy savings were likely. Secondly, a detailed analysis of the energy used by the boiler-house is- carried out. A real time monitoring and targeting system which records and displays boiler, environmental and plant parameters is developed and installed. Data gathered over a period of six months enables (i) specific cases of energy wastage resulting from operational procedures to be identified and (ii) trends of performance indicating poor energy efficiency to be traced. The system developed may be used to provide the information necessary to enable improved control. A general result which may be inferred from this work would be that the combined approaches of a topdown general analysis and a bottom-up detailed analysis of energy use can provide significant opportunities for energy conservation resulting solely from the improved operation of large energy consuming plant. The work was performed at a major manufacturing plant in the U. K. with an annual energy consumption of the order of 600 gigawatt-hours and an annual energy bill of the order of E10 million.

This dissertation develops new techniques to reduce computational complexity for hyperspectral remote sensing image analysis. Specific techniques are applied with regards to different applications of hyperspectral imagery, i.e., classification, target detection. The contribution of this dissertation can be summarized as follows. 1. A time efficient version combining multiple collaborative representations model is proposed for hyperspectral image classification. Collaborative representation (CR) can be implemented either with a dictionary containing training samples of all-classes or class-specific. A collaborative representation optimized classifier with Tikhonov regularization (CROCT) is proposed to avoid the redundant operations in all-class and class-specific versions. 2. An efficient probabilistic collaborative representation is presented for hyperspectral image classification. Its performance is evaluated on different types of spatial features of hyperspectral imagery including shape feature (i.e., extended multi-attribute feature), global feature (i.e., Gabor feature), and local feature (i.e., Local Binary Pattern). Experimental results show the probabilistic collaborative representation based classifier (PROCRC) has excellent performance in terms of both accuracy and computational cost compared with the original CRC and regularized versions of CRC. 3. Fast nonlinear classification and an explicit kernel approach are built for multispectral and hyperspectral imagery respectively to improve the kernel version of collaborative representation based algorithms. Experimental results show that using artificial bands generated from a simple band ratio function can yield better classification accuracy than the nonlinear kernel method and also reduce computational cost. In addition, the explicit kernel mapping approach can yield high accuracy as the original kernel versions of CR-based algorithms but with similarly low computational cost as in the original linear CRC classifiers. 4. Efficient band selection approaches are proposed for hyperspectral target detection. A maximum-sub-maximum ratio (MSR) metric has been applied for band selection, which can well gauge the target background separation. Efficient evolutionary searching methods such as particle swarm optimization and firefly algorithm are used in conjunction with maximum-sub-maximum ratio metric for band selection. Experimental results show that the proposed band selection approach can select a small band set while yielding similar detection performance compared with using all the original bands.

No description available.

Microprocessors are used in a variety of systems ranging from high-performance super computers running scientific applications to battery powered cell phones performing realtime tasks. Due to the large disparity between processor clock speed and main memory access time, most modern processors include several caches, which consume more than half of the total chip area and power budget. As the performance gap between processors and memory has increased, the trend has been to increase the size of the on-chip caches. However, increasing the cache size also increases its access time and energy consumptions. This growing power dissipation problem is making traditional cooling and packaging techniques less effective thus requiring cache designers to focus more on architectural level energy efficiency than performance alone. The goal of this thesis is to propose a new cache architecture and to evaluate its efficiency in terms of miss rate, system performance, energy consumption, and area overhead. The proposed architecture employs the use of a few Ternary-CAM (TCAM) cells in the tag array to enable dynamic compression of tag entries containing contiguous values. By dynamically compressing tag entries, the number of entries in the tag array can be reduced by 2N, where N is the number of tag bits that can be compressed. The architecture described in this thesis is applicable to any cache structure that uses Content Addressable Memory (CAM) cells to store tag bits. To evaluate the effectiveness of the TCAM Enhanced Cache Architecture for a wide scope of applications, two case studies were performed ?? the L2 Data-TLB (DTLB) of a high-performance processor and the L1 instruction and data caches of a low-power embedded processor. Results indicate that a L2 DTLB implementing 3-bit tag compression can achieve 93% of the performance of a conventional L2 DTLB of the same size while reducing the on-chip energy consumption by 74% and the total area by 50%. Similarly, an embedded processor cache implementing 2-bit tag compression achieves 99% of the performance of a conventional cache while reducing the on-chip energy consumption by 33% and the total area by 10%.

Implementing demand side management (DSM) is expensive and often time consuming. Eskom grants subsidies for DSM projects based on the proposed savings. The subsidy granted is not always adequate to fund all the required control equipment to achieve the desired saving. This study focuses on alternative cost– and time–effective methods to implement DSM on gold mines, specifically on the compressed–air systems where the infrastructure is inadequate, worn out or outdated. The compressors generating compressed air for mining are one of the largest electricity consumer at gold mines. By optimising the energy consumption of these compressed–air systems, the largest potential demand reduction can be achieved. This will lighten the demand load on the already overloaded national power grid. Compressed air at gold mines is mainly used for production purposes, thus the majority of savings on these systems need to be achieved during non–production hours. Fixing air leaks, optimising compressor control, meticulous planning of implementation locations and controlling air usage are all methods that were investigated to achieve alternative cost– and time–effective methods to implement DSM on mine compressed–air systems. The methods were implemented by an Energy Services Company (ESCo) at four different mines. The results achieved from these case studies are documented and discussed in this study. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2011.

Implementing demand side management (DSM) is expensive and often time consuming. Eskom grants subsidies for DSM projects based on the proposed savings. The subsidy granted is not always adequate to fund all the required control equipment to achieve the desired saving. This study focuses on alternative cost– and time–effective methods to implement DSM on gold mines, specifically on the compressed–air systems where the infrastructure is inadequate, worn out or outdated. The compressors generating compressed air for mining are one of the largest electricity consumer at gold mines. By optimising the energy consumption of these compressed–air systems, the largest potential demand reduction can be achieved. This will lighten the demand load on the already overloaded national power grid. Compressed air at gold mines is mainly used for production purposes, thus the majority of savings on these systems need to be achieved during non–production hours. Fixing air leaks, optimising compressor control, meticulous planning of implementation locations and controlling air usage are all methods that were investigated to achieve alternative cost– and time–effective methods to implement DSM on mine compressed–air systems. The methods were implemented by an Energy Services Company (ESCo) at four different mines. The results achieved from these case studies are documented and discussed in this study. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2011.