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Jennifer Therkorn David Drewry III Thomas Pilholski Kathryn Shaw‐Saliba Gregory Bova Lisa L. Maragakis Brian Garibaldi Lauren Sauer 《Indoor air》2019,29(1):143-155
Biocontainment units (BCUs) are facilities used to care for patients with highly infectious diseases. However, there is limited guidance on BCU protocols and design. This study presents the first investigation of how HVAC (heating, ventilation, air‐conditioning) operating conditions influence the dissemination of fluorescent tracer particles released in a BCU. Test conditions included normal HVAC operation and exhaust failure resulting in loss of negative pressure. A suspension of optical brightener powder and water was nebulized to produce fluorescent particles simulating droplet nuclei (0.5‐5 μm). Airborne particle number concentrations were monitored by Instantaneous Biological Analyzers and Collectors (FLIR Systems). During normal HVAC operation, fluorescent tracer particles were contained in the isolation room (average concentration = 1 × 104 ± 3 × 103/Lair). Under exhaust failure, the automated HVAC system maximizes airflow into areas adjacent to isolation rooms to attempt to maintain negative pressure differential. However, 6% of the fluorescent particles were transported through cracks around doors/door handles out of the isolation room via airflow alone and not by movement of personnel or doors. Overall, this study provides a systematic method for evaluating capabilities to contain aerosolized particles during various HVAC scenarios. Recommendations are provided to improve situation‐specific BCU safety. 相似文献
63.
A unique strain gauge based method is developed to identify the magnitude and location of a load on a slender beam with variable cross sections, and pinned, firm rest, soft rest, pinned‐fixed, and fixed boundary conditions. Four uniaxial strain gauges are mounted to the bottom surface of the beam, and the bending moment diagram of the beam can be constructed using measured strains on the beam. By combining individually scaled strain gauge outputs, the magnitude and location of the load can be accurately identified. The strain gauge based force transducer methodology is experimentally validated on prismatic beams with firm rest, soft rest, firm rest‐fixed, and fixed boundary conditions, and a continuously tapered beam with rest boundary conditions. The force transducer methodology is independent of the boundary conditions of the beam, and the error from strain gauge drift due to uniform thermal expansion on a prismatic beam can cancel out. 相似文献
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Mohamad-Ali Mortada Thomas Carroll III Soumaya Yacout Aouni Lakis 《Journal of Intelligent Manufacturing》2012,23(2):289-302
There is a small subset of any repairable component population that can develop a failure mode outside the scope of the standard
repair and overhaul procedures, which makes them “rogue”. When this happens, a Darwinian-like “natural selection” phenomenon
ensures that they will be placed in the most disadvantageous position in the asset management program, negatively affecting
multiple aspects of the operational and maintenance organizations. Rogue components have long plagued the airline industry
and created havoc in their asset management programs. In this paper, we describe how these rogues develop, outline the natural
selection process that leads to their hampering the asset management program, and examine some of the negative impacts that
ensue. Then we propose a Condition based maintenance approach to control the development of these components. We explore the
use of a supervised learning data mining technique called Logical analysis of data (LAD) in CBM for the purpose of detecting
rogues within a population of repairable components. We apply the resulting LAD based decision model on an inventory of turbo
compressors belonging to an airline fleet. Finally, we evaluate the applicability of LAD to the rogue component detection
problem and review its efficiency as a decision model for this type of problem. 相似文献
66.
HAROLD W. LEWIS III 《国际通用系统杂志》2013,42(1-2):97-114
Abstract On the subject of fuzzy set-based approximate reasoning, this paper attempts to present a perspective that is both rigorously stated and different from the standard approach as stated by Mamdani and many others. Functionally speaking, this alternative perspective produces results essentially the same as the standard one, and in fact we intend to prove that subject to certain assumptions the results will be exactly die same. We feel however that the alternative perspective offers advantages in that it makes a more appropriate and more understandable use of such concepts as fuzzy relations, the extension principle, and fuzzy composition. If indeed it can lead to a clearer and more widespread understanding of the approximate reasoning formalism then this could conceivably spark broader interest in fuzzy control and other applications. 相似文献
67.
Efficacy of Citrilow and Cecure spray wash on prevalence of aerobic and Enterobacteriaceae bacteria/gram‐negative enteric bacilli and cattle hide quality 下载免费PDF全文
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69.
Juan P. Escobedo Ellen K. Cerreta Daniel T. Martinez Carl P. Trujillo Ricardo A. Lebensohn George T. Gray III 《Metallurgical and Materials Transactions A》2014,45(13):5877-5882
The influence of temperature on the dynamic tensile behavior of Zr has been investigated. Bullet-shaped Zr samples with two different textures were dynamically extruded at room temperature and 523 K (250 °C). A higher ductility was measured for samples deformed at elevated temperature as compared to those extruded at room temperature. This difference in ductility is discussed in terms of zirconium’s ability to accommodate plastic deformation via thermally enhanced slip activity, as evidenced by examination of the deformed microstructures. 相似文献
70.