Lehigh University

About: Lehigh University is a education organization based out in Bethlehem, Pennsylvania, United States. It is known for research contribution in the topics: Catalysis & Fracture mechanics. The organization has 12684 authors who have published 26550 publications receiving 770061 citations.

Control Mechanisms for Residential Electricity Demand in SmartGrids

Abstract: We consider mechanisms to optimize electricity consumption both within a home and across multiple homes in a neighborhood. The homes are assumed to use energy management controllers (EMCs) to control the operation of some of their appliances. EMCs, which are a feature of the emerging SmartGrid, use both prices and user preferences to control power usage across the home. We first present a simple optimization model for determining the timing of appliance operation to take advantage of lower electricity rates during off-peak periods. We then demonstrate, using simulation, that the resulting solution may in fact be more peaky than the ``non-scheduled'' solution, thereby negating some of the benefits (for the utility) of off-peak pricing models. We then propose a distributed scheduling mechanism to reduce peak demand within a neighborhood of homes. The mechanism provides homes a guaranteed base level of power and allows them to compete for additional power to meet their needs. Finally, we introduce a more powerful EMC optimization model, based on dynamic programming, which, unlike our first optimization model, accounts for the potential for electricity capacity constraints.

Restoration of Bridge Networks after an Earthquake: Multicriteria Intervention Optimization

Abstract: This paper presents an optimization procedure for the restoration activities associated with the bridges of a transportation network severely damaged by an earthquake. The design variables are (i) the time intervals between the occurrence of the distress and the start of the interventions on each bridge of the network; and (ii) the restoration pace of the interventions, which represents a measure of the funding allocated to each bridge. The objectives of the optimization are the maximization of the network resilience, the minimization of the time required to reach a target functionality level, and the minimization of the total cost of the restoration activities. Because the first two objectives clearly conflict with the last one, the optimization procedure does not provide a unique solution, but an entire set of Pareto solutions. A numerical example involving a complex, existing transportation network in Santa Barbara, California, illustrates the capabilities of the proposed methodology.

Threshold for Fatigue Crack Propagation and the Effects of Load Ratio and Frequency

Abstract: The threshold in the alternating range of stress intensity factor for fatigue crack growth is investigated for 2024-T3 aluminum. Testing techniques provided displacement control at frequencies up to 1000 Hz. The thresholdis seen to decrease with increasing frequency at a fixed load ratio, dropping by nearly a factor of 2 from 342 to 832 Hz. The threshold is also observed to decrease with increasing load ratio in such a way that is tentatively explained by considerations of crack closure. Some confirmation of this is obtained from direct strain gage measurement of the closure stress intensity, K c , which agrees with that predicted from trends in the threshold data with respect to load ratio.