Energy-Efficient Algorithms

We initiate the systematic study of the energy complexity of algorithms (in addition to time and space complexity) based on Landauer's Principle in physics, which gives a lower bound on the amount of energy a system must dissipate if it destroys information. We propose energy-aware variations of three standard models of computation: circuit RAM, word RAM, and transdichotomous RAM. On top of these models, we build familiar high-level primitives such as control logic, memory allocation, and garbage collection with zero energy complexity and only constant-factor overheads in space and time complexity, enabling simple expression of energy-efficient algorithms. We analyze several classic algorithms in our models and develop low-energy variations: comparison sort, insertion sort, counting sort, breadth-first search, Bellman-Ford, Floyd-Warshall, matrix all-pairs shortest paths, AVL trees, binary heaps, and dynamic arrays. We explore the time/space/energy trade-off and develop several general techniques for analyzing algorithms and reducing their energy complexity. These results lay a theoretical foundation for a new field of semi-reversible computing and provide a new framework for the investigation of algorithms.Comment: 40 pages, 8 pdf figures, full version of work published in ITCS 201

Steam bottoming cycle for an adiabatic diesel engine

Steam bottoming cycles using adiabatic diesel engine exhaust heat which projected substantial performance and economic benefits for long haul trucks were studied. Steam cycle and system component variables, system cost, size and performance were analyzed. An 811 K/6.90 MPa state of the art reciprocating expander steam system with a monotube boiler and radiator core condenser was selected for preliminary design. The costs of the diesel with bottoming system (TC/B) and a NASA specified turbocompound adiabatic diesel with aftercooling with the same total output were compared, the annual fuel savings less the added maintenance cost was determined to cover the increase initial cost of the TC/B system in a payback period of 2.3 years. Steam bottoming system freeze protection strategies were developed, technological advances required for improved system reliability are considered and the cost and performance of advanced systes are evaluated

A CFD model of erosion-corrosion of Fe at elevated temperatures in aqueous environments

In studies of erosion-corrosion at materials at elevated temperatures, there have been many attempts to model the process. Such models have comprised quasi-static and simulation models. However in many environments, erosion-corrosion occurs in aqueous conditions and can be considerably affected by flowing gases in dry conditions. In such cases, any accurate models of erosion-corrosion must include an algorithm due to flow in addition to the mechanics and chemistry of the tribo-corrosion interactions. In this paper, a CFD model is generated of the tribo-chemical interaction at elevated temperatures. The initial work has concentrated on modeling temperature effects in wet conditions; however, the potential application of the model to dry conditions is also outlined. The results are discussed in relation to existing erosion-corrosion models in the literature at elevated temperatures

Daily weather direct readout microprocessor study

The work completed included a study of the requirements and hardware and software implementation techniques for NIMBUS ESMR and TWERLE direct readout applications using microprocessors. Many microprocessors were studied for this application. Because of the available Interdata development capabilities, it was concluded that future implementations be on an Interdata microprocessor which was found adequate for the task