An Assessment of Economic Analysis Methods for Cogeneration Systems

Cogeneration feasibility studies were conducted for eleven state agencies of Texas. A net present value (NPV) analysis was used to evaluate candidate cogeneration systems and select the optimum system. CELCAP, an hour-by-hour cogeneration analysis computer program was used to determine the costs used in the NPV analysis. The results of the studies showed that the state could save over $6,000,000 per year in reduced utility bills. Different methods of analyzing the economic performance of a cogeneration system are presented for comparison. Other implications of the study are also discussed

A Multi-Fidelity Prediction of Aerodynamic and Sonic Boom Characteristics of the JAXA Wing Body

This paper presents a detailed comparison between the linear panel solver PANAIR A502 and the in-house Navier–Stokes solver UNS3D for a supersonic low-boom geometry. The high-fidelity flow solver was used to predict both the inviscid and laminar flow about the aircraft geometry. The JAXA wing body was selected as the supersonic low-boom geometry for this study. A comparison of the undertrack near-field pressure signatures showed good agreement between the three levels of model fidelity along the first 0.8L of the signature. Large oscillations in the PANAIR results were observed. The PANAIR discrepancies were traced back to violations of the underlying assumptions within PANAIR: (1) small perturbation velocities and (2) no regions of transonic flow. These violations were due to large changes in surface curvature resulting in a strong expansion wave. While investigating the PANAIR discrepancy, measures of the fundamental assumptions of the Prandtl-Glauert equation used by PANAIR were quantified and used to assess the applicability of PANAIR to a given problem. Further comparison of surface temperatures predicted between the inviscid and laminar solutions was made. It was found that the recovery temperatures predicted by the inviscid solution were 5% less than those predicted by the laminar solution in likely candidate regions for distributed adaptivity. A surface deformation was added to the forward portion of the geometry to asses the viability of a future optimization study in this region. In this study, it was found that the near-field and ground signatures predicted by PANAIR and the UNS3D solutions responded in similar manners to the deformation

Logic, Probability and Action: A Situation Calculus Perspective

The unification of logic and probability is a long-standing concern in AI, and more generally, in the philosophy of science. In essence, logic provides an easy way to specify properties that must hold in every possible world, and probability allows us to further quantify the weight and ratio of the worlds that must satisfy a property. To that end, numerous developments have been undertaken, culminating in proposals such as probabilistic relational models. While this progress has been notable, a general-purpose first-order knowledge representation language to reason about probabilities and dynamics, including in continuous settings, is still to emerge. In this paper, we survey recent results pertaining to the integration of logic, probability and actions in the situation calculus, which is arguably one of the oldest and most well-known formalisms. We then explore reduction theorems and programming interfaces for the language. These results are motivated in the context of cognitive robotics (as envisioned by Reiter and his colleagues) for the sake of concreteness. Overall, the advantage of proving results for such a general language is that it becomes possible to adapt them to any special-purpose fragment, including but not limited to popular probabilistic relational models

Numerical modeling of the tension stiffening in reinforced concrete members via discontinuum models

[prova tipográfica]This study presents a numerical investigation on the fracture mechanism of tension stiffening phenomenon in reinforced concrete members. A novel approach using the discrete element method (DEM) is proposed, where three-dimensional randomly generated distinct polyhedral blocks are used, representing concrete and one-dimensional truss elements are utilized, representing steel reinforcements. Thus, an explicit representation of reinforced concrete members is achieved, and the mechanical behavior of the system is solved by integrating the equations of motion for each block using the central difference algorithm. The inter-block interactions are taken into consideration at each contact point with springs and cohesive frictional elements. Once the applied modeling strategy is validated, based on previously published experimental findings, a sensitivity analysis is performed for bond stiffness, cohesion strength, and the number of truss elements. Hence, valuable inferences are made regarding discontinuum analysis of reinforced concrete members, including concrete-steel interaction and their macro behavior. The results demonstrate that the proposed phenomenological modeling strategy successfully captures the concrete-steel interaction and provides an accurate estimation of the macro behavior