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Barton M.D.,Dartmouth College | Barton M.D.,Creare Inc. | Trembly B.S.,Dartmouth College
Experimental Eye Research | Year: 2013

Accurate thermal models for the cornea of the eye support the development of thermal techniques for reshaping the cornea and other scientific purposes. Heat transfer in the cornea must be quantified accurately so that a thermal treatment does not destroy the endothelial layer, which cannot regenerate, and yet is responsible for maintaining corneal transparency. We developed a custom apparatus to measure the thermal conductivity of exvivo porcine corneas perpendicular to the surface and applied a commercial apparatus to measure thermal conductivity parallel to the surface. We found that corneal thermal conductivity is 14% anisotropic at the normal state of corneal hydration. Small numbers of exvivo feline and human corneas had a thermal conductivity perpendicular to the surface that was indistinguishable from the porcine corneas. Aqueous humor from exvivo porcine, feline, and human eyes had a thermal conductivity nearly equal to that of water. Including the anisotropy of corneal thermal conductivity will improve the predictive power of thermal models of the eye. © 2013. Source

Micka D.J.,University of Michigan | Micka D.J.,Creare Inc. | Driscoll J.F.,University of Michigan
Combustion and Flame | Year: 2012

Measurements are reported of the heat release profiles, the flame lengths, flame structure and other properties of a reacting jet-in-cross-flow (JICF) for two fuels. The air was heated to a static temperature of 1390K, which is above the autoignition temperature, and the air velocity was 468m/s, which is much larger than values that were considered previously. Aerodynamic strain rates are so large that the flame was expected to fall into either the " distributed reaction" , " thickened flamelet" , or " shredded flamelet" regimes. Fluorescence images of CH, OH and formaldehyde identified the flame structure. The jet-in-cross-flow is a unit physics problem that occurs in turbojets and scramjets. While scaling relations are known for the non-reacting case, more information about the reacting case is needed, especially when autoignition and strain rates become important. Three regions were identified. In the liftoff region autoignition reactions occur which create a strong formaldehyde PLIF signal. However, flames and heat release do not occur in the liftoff region since CH and CH * signals were negligible. The second region is the lifted flame base, which has the character of a premixed flame, as evidenced by a very rapid rise in the heat release rate as indicated by the CH * and OH * signals. The third region contains a turbulent non-premixed flame and the CH images indicate the presence of thickened and shredded flamelets. The 2-3mm thickness of each CH layer is more than 10times the laminar flamelet thickness. In the third region the heat release rate decays slowly downstream, which is typical of a non-premixed flame. Because both upstream autoignition and downstream thickened flamelets were observed, we classify this combustion to be an " autoignition-assisted flame" Flame lengths increase linearly with fuel mass flow rate, indicating that mixing is controlled by the air velocity rather than the fuel velocity. © 2011 The Combustion Institute. Source

Allen L.V.,Creare Inc. | Tilbury D.M.,University of Michigan
IEEE Transactions on Systems, Man, and Cybernetics Part A:Systems and Humans | Year: 2012

Detecting and debugging faults more efficiently can significantly improve the performance of systems, and a first step toward fault detection is anomaly detection. A new anomaly detection solution is proposed in this paper for event-based systems that consist of processes that interact through shared resources and that do not have a preexisting formal discrete event system model. This solution generates models of the system, assesses the models' performance in detecting faults, and then uses the models and their performance to detect anomalies in new event streams. A new resource-based Petri net formalism is introduced to model these types of systems. The model generation uses an algorithm based on workflow mining to generate resource-based models. The proposed solution is demonstrated on two manufacturing cell examples. © 2012 IEEE. Source

Chen W.,Creare Inc.
Cryogenics | Year: 2014

This paper discusses the design of a micromachined regenerator in an Active Magnetic Regenerative Refrigeration (AMRR) system for space applications. The AMRR system is designed to provide continuous remote/distributed cooling at about 2 K and reject heat at temperatures of about 15 K. This paper first discusses the general thermal and fluid performance requirements for an AMRR regenerator, a unique structured bed configuration that enables the regenerator to meet these requirements, and its thermal and fluid performance based on numerical analyses. The paper then discusses the general design consideration for the magnetic field driving the regenerator for optimal thermal performance, and the analysis processes to optimize the variation rate of the magnetic field in an actual superconducting magnet during the isothermal processes of the AMRR cycle to enhance the performance of an actual regenerator. The paper finally presents the thermal performance of the regenerator from such iterative design optimization processes. © 2014 Elsevier Ltd. All rights reserved. Source

The United States Of America and Creare Incorporated | Date: 2013-06-24

A nasal delivery device can include air-receiving section that has a first passageway therethrough to allow air to pass through the air-receiving section, a powder-reservoir receiving section sized to receive a powder reservoir, and a powder-delivery section that has a second passageway therethrough to allow aerosolized powder from the powder reservoir to pass through the powder-delivery section. The first passageway can have a first end and a second end, with the first end being further from the powder-reservoir receiving section and the second end being at or near the powder-reservoir receiving area. The second end of the air-receiving section can include a flattened region so that air exiting the air-receiving section has a generally flattened profile.

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