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排序方式: 共有264条查询结果,搜索用时 15 毫秒
1.
R. C. Pennefather D. H. Boone 《International Journal of Pressure Vessels and Piping》1996,66(1-3):351-358
Cyclic oxidation tests were performed on a large variety of commercially available overlay coatings. The results of cyclic oxidation tests confirmed that the composition of the coating as well as the processing method of the coating can affect the life of the system. Coating life was determined by the time to coating penetration and initiation of substrate attack. As this work was part of a effort to evaluate the relative protectiveness of available coating systems for Industrial Gas Turbine applications at relatively high temperature, an extensive testing programme was undertaken. The different coatings were tested to visual failure. The results presented in this paper concentrate on the surface instability of the coating. Apart from usual oxidation of the coating an additional degradation mechanism was observed. A mechanical effect caused by the instability of the coating as a result of the difference in the thermal coefficient of expansion and mechanical properties between the substrate and coating. This effect, the so-called “rumpling” effect, resulted in a significant reduction in time to penetration and was in some systems the life controlling factor. 相似文献
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H. Tsukamoto T.D. Boone J. Han J.M. Woodall 《Photonics Technology Letters, IEEE》2005,17(7):1411-1413
We present a novel optical switching technique utilizing emission packet positioning of semiconductor heterostructure. A modulation-doped p-AlGaAs-GaAs heterostructure is employed to control spontaneous emission packet positioning with electric fields. Emission packets generated by optical input signals are brought over 150 /spl mu/m with electric fields, so the output fibers can detect the emission intensity as signals. The first-order analysis indicates that the drift velocity of minority electrons in GaAs limits the detectable maximum data rate and nanoseconds timescale signal routing operation at 20 Gb/s is possible at an electron drift velocity of 2/spl times/10/sup 7/ cm/s. 相似文献
3.
Sandra L. McLellan Erika J. HollisMorgan M. Depas Meredith Van DykeJosh Harris Caitlin O. Scopel 《Journal of Great Lakes research》2007,33(3):566-580
Escherichia coli distribution and persistence in nearshore Lake Michigan were assessed following heavy rains and sanitary sewer overflow (SSO) and combined sewer overflow (CSO) events over a 5-year period, including an 18-day period following 25.4 cm of rainfall in which intensive studies were conducted following multiple CSO and SSO events. E. coli levels in the Milwaukee estuary and harbor following SSO and CSO events ranged from 104 to nearly 105 CFU/100 mL, which were significantly higher (p ≤ 0.05) than levels following rainfall alone. Sites outside of the breakwall but within the contamination plume (e.g., within 2 km of the harbor) were an order of magnitude lower. Locations 2–5 km from the harbor ranged from below detection limits, of < 1 to 5 CFU/100 mL. E. coli levels corrected for dilution based on specific conductivity measurements were lower than what would be expected for loss due to dilution alone, suggesting a combination of die-off and dilution, were responsible for the rapid disappearance of these organisms outside of the harbor. E. coli and fecal coliforms measured concurrently demonstrated that fecal coliforms could be recovered longer than E. coli in the open waters of the lake. E. coli isolated directly from sewage treatment plant influent were found to have a marked increase in antibiotic resistance traits for ten antibiotics commonly used in the human population compared with isolates from two animal sources of fecal pollution. However, E. coli obtained from sewage impacted water (n = 2,513) and from stormwater impacted water (n = 1,465) collected the previous year when there were no sewage overflows, were found to have no significant difference (p < 0.05) in the frequency of resistance when comparing the two conditions. E. coli survival characteristics and population dynamics are most likely influenced by multiple factors in complex systems such as the watershed/estuarine/lake environments of the Great Lakes. 相似文献
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Rapid building detection using machine learning 总被引:1,自引:0,他引:1
Joseph Paul Cohen Wei Ding Caitlin Kuhlman Aijun Chen Liping Di 《Applied Intelligence》2016,45(2):443-457
This work describes algorithms for performing discrete object detection, specifically in the case of buildings, where usually only low quality RGB-only geospatial reflective imagery is available. We utilize new candidate search and feature extraction techniques to reduce the problem to a machine learning (ML) classification task. Here we can harness the complex patterns of contrast features contained in training data to establish a model of buildings. We avoid costly sliding windows to generate candidates; instead we innovatively stitch together well known image processing techniques to produce candidates for building detection that cover 80–85 % of buildings. Reducing the number of possible candidates is important due to the scale of the problem. Each candidate is subjected to classification which, although linear, costs time and prohibits large scale evaluation. We propose a candidate alignment algorithm to boost classification performance to 80–90 % precision with a linear time algorithm and show it has negligible cost. Also, we propose a new concept called a Permutable Haar Mesh (PHM) which we use to form and traverse a search space to recover candidate buildings which were lost in the initial preprocessing phase. All code and datasets from this paper are made available online (http://kdl.cs.umb.edu/w/datasets/ and https://github.com/caitlinkuhlman/ObjectDetectionCLUtility). 相似文献
7.
Winson C C Lee Ming Zhang Peggy P Y Chan David A Boone 《IEEE transactions on neural systems and rehabilitation engineering》2006,14(3):370-377
The latest lower-limb prosthetic designs have been incorporated with dynamic elastic response (DER) components to enhance prosthesis flexibility, which are suggested to be beneficial to gait. Although DER prosthetic. feet are preferred by most transtibial amputees and their benefits to gait are supported by some biomechanical studies, many are still utilizing the simple conventional solid ankle cushioned heel (SACH) designs because of the lower cost. The monolimb, a transtibial prosthesis with the socket and the shank molded from a single piece of thermoplastic material, perhaps is an alternative to DER feet for providing flexibility at the shank. In addition to shank flexibility, low cost and light weight are other characteristics of monolimbs. In spite of the potential benefits, little analysis has been done to examine the simple-structured monolimb prosthesis. The main aim of this study is to evaluate the gait and perception of unilateral transtibial amputees using a flexible elliptical-shank monolimb as compared to a thicker circular-shank monolimb and a conventional rigid-shank prosthesis. Results suggested that a properly designed monolimb may potentially offer similar functional advantages to the relatively expensive DER feet. 相似文献
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Knowles Eric D.; Lowery Brian S.; Hogan Caitlin M.; Chow Rosalind M. 《Canadian Metallurgical Quarterly》2009,96(4):857
The authors propose that the content of certain sociopolitical ideologies can be shaped by individuals in ways that satisfy their social motivations. This notion was tested in the context of color-blind ideology. Color blindness, when construed as a principle of distributive justice, is an egalitarian stance concerned with reducing discrepancies between groups' outcomes; as a principle of procedural justice, however, color blindness can function as a legitimizing ideology that entrenches existing inequalities. In Study 1, White people high in antiegalitarian sentiment were found to shift their construal of color blindness from a distributive to a procedural principle when exposed to intergroup threat. In Studies 2, 3A, and 3B, the authors used manipulations and a measure of threat to show that antiegalitarian White people endorse color blindness to legitimize the racial status quo. In Study 3B, participants' endorsement of color-blind ideology was mediated by increases in their preference for equal treatment (i.e., procedural justice) as a response to threat. In the Discussion section, the authors examine implications of the present perspective for understanding the manner in which individuals compete over the meaning of crucial ideologies. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Linda M. Gallant Cynthia Irizarry Gloria M. Boone Brenna Ruiz‐Gordon 《Journal of Computer-Mediated Communication》2010,15(4):552-574
This study explores the nature and extent of Spanish language translation of hospital websites. A quantitative content analysis of 121 U.S. hospital websites located in Hispanic communities was conducted. Results indicate that a significant number of U.S. hospitals fail on their websites to offer equal content for Spanish language users. The study also examines several factors potentially associated with the incidence of website translation. First, organizational factors such as hospital size, ownership type and formal statements of diversity commitment are investigated. Second, demographic factors such as county population size and Hispanic population size are also considered. Hispanics' use of the Internet, the digital divide, culture's impact on Internet use, and eHealth provide a background for discussion of the findings. 相似文献