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排序方式: 共有272条查询结果,搜索用时 15 毫秒
91.
92.
Kevin Curran Derek Woods Nadene McDermot Colleen Bradley 《International Journal of Network Management》2003,13(1):83-94
From an exhaustive series of trace packets to a diverse set of destinations, our research has discovered that specific routers are the cause of bottlenecks in the Internet. We found that packets took the same route each time towards their destination. Our research has also found that over periods as large as seven days these routers continue to cause bottlenecks with no re‐routing of packets to alleviate congestion. This research begs the question as to why these bottlenecks occur at the same places and for so long a period and also queries the extent of implementation of dynamic routing algorithms. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
93.
Daniel R. Mumm David B. Marshall Alair Griffin Curtis W Griffin Colleen S. Turner 《Journal of the American Ceramic Society》1996,79(5):1416-1418
The hardness of zirconia-alumina laminar composites has been measured over contact size scales ranging from much smaller to much larger than the layer thicknesses. The results correlate with a weighted average of the hardnesses of the two layer constituents based on the volume of the plastic zone; and they deviate significantly from a similar average based on the contact area. 相似文献
94.
95.
Matvey Greg; Dunlosky John; Shaw Raymond J.; Parks Colleen; Hertzog Christopher 《Canadian Metallurgical Quarterly》2002,17(4):589
Knowledge updating involves learning about cue effectiveness based on task experience. Prior research has yielded inconsistent conclusions regarding age and knowledge updating. To resolve this inconsistency, the authors analyzed the effects of aging within a single paradigm. Participants studied cue-target associates during 2 study-test trials. Cues included rhyme cues and highly effective category cues. On each study-test trial, different items were presented, and participants predicted recall performance, received a cued recall test, and postdicted performance. Knowledge updating was operationalized as an improvement in the accuracy of predictive judgments across trials. An age deficit was evident in improvements in absolute accuracy, whereas age equivalence was evident in relative accuracy. Evidence suggested that deficient inferential processes contributed to the age deficit in knowledge updating. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
96.
97.
Hayden Elizabeth P.; Bodkins Misty; Brenner Colleen; Shekhar Anantha; Nurnberger John I. Jr.; O'Donnell Brian; Hetrick William P. 《Canadian Metallurgical Quarterly》2008,117(1):164
Dysregulation in behavioral activation system (BAS) activity has been implicated in the pathogenesis of bipolar disorder (BPD). To characterize BAS activity and related facets in this disorder, the authors compared 59 participants with BPD to 44 controls on multiple measures of BAS activity, including a standardized behavioral task, self-reports, and electroencephalographic indexes of regional cortical activity. Levels of putative BAS activity differed depending on assessment strategy. When a behavioral task indexing reward sensitivity was used, euthymic BPD patients showed evidence of higher BAS activity than either control participants or patients who were in a mood episode. Following a mood induction procedure designed to elicit BAS activity, currently episodic patients showed relatively greater left anterior cortical activity than either euthymic or control participants. Implications of the findings for future research on BPD vulnerability are described. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
98.
This paper describes an investigation into the sprinkler response time predictive capability of the BRANZFIRE fire model.
A set of 22 fire/sprinkler experiments are simulated where the sprinkler activation time and the heat release rate (HRR) for
each individual experiment had been determined. The experiments provided data for use in validating the sprinkler activation
prediction algorithms in the BRANZFIRE zone model.
A set of base case values were chosen and input files constructed for the simulations. The experiments were then simulated
by the fire model using both the NIST/JET ceiling jet and Alpert’s ceiling jet options (which are the two ceiling jet correlations
available in the BRANZFIRE zone model). The fire model included a heat transfer calculation for the temperature of the heat
sensitive sprinkler element. Different sprinkler operational parameters such as the conduction factor, response time index
(RTI) and the sprinkler depth below ceiling were also varied to assess the sensitivity of their effect on the activation time.
Results showed that using the NIST/JET ceiling jet algorithm gave a closer prediction of the sprinkler response time in a
small room than Alpert’s correlation. This was expected, since the former includes the effect of a hot upper layer while the
latter applies to unconfined ceilings. The experiments available for comparison had been conducted inside an enclosure with
a developing hot upper layer. The findings also signified that changing the sprinkler operational parameters can change the
predicted sprinkler activation time significantly. 相似文献
99.
Colleen Stroud Melvyn C. Branch Trina Vian Neal Sullivan Mark Strobel Michael Ulsh 《Fuel》2008,87(10-11):2201-2210
This study focuses on the key parameters that enhance the stability of ribbon burners used in various industrial processes, characterizing the flame environment and flow regimes that the burner creates under changing operating conditions. The research includes the exploration of ribbon-pack configurations in order to define the effects of separation distance and port arrangement on flame stability and thermal and fluid flow. Flow visualization studies reveal that burners having a 1.5–2.0 mm division between rows appear to be the most stable. More than four rows of ports in the ribbon-pack are required to resist entrainment of ambient air as a result of impinging surface motion. The flame environment created by the ribbon burner experiences higher levels of mixing, at a lower Reynolds number in comparison to a single non-reacting jet due to combustion-induced turbulence and jet interaction. Under these high flow velocity conditions there is little entrainment of ambient air along the impingement surface and a very stable flame environment is created. 相似文献
100.
A research study has been performed to determine the ultraviolet (UV) fluence-response of several target non-pathogenic microorganisms to UV light emitting diodes (UV-LEDs) by performing collimated beam tests. UV-LEDs do not contain toxic mercury, offer design flexibility due to their small size, and have a longer operational life than mercury lamps. Comsol Multiphysics was utilized to create an optimal UV-LED collimated beam design based on number and spacing of UV-LEDs and distance of the sample from the light source while minimizing the overall cost. The optimized UV-LED collimated beam apparatus and a low-pressure mercury lamp collimated beam apparatus were used to determine the UV fluence-response of three surrogate microorganisms (Escherichia coli, MS-2, T7) to 255 nm UV-LEDs, 275 nm UV-LEDs, and 254 nm low-pressure mercury lamps. Irradiation by low-pressure mercury lamps produced greater E. coli and MS-2 inactivation than 255 nm and 275 nm UV-LEDs and similar T7 inactivation to irradiation by 275 nm UV-LEDs. The 275 nm UV-LEDs produced more efficient T7 and E. coli inactivation than 255 nm UV-LEDs while both 255 nm and 275 nm UV-LEDs produced comparable microbial inactivation for MS-2. Differences may have been caused by a departure from the time-dose reciprocity law due to microbial repair mechanisms. 相似文献