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排序方式: 共有1079条查询结果,搜索用时 15 毫秒
101.
William Whittaker Peter Staritz Rob Ambrose Brett Kennedy Stephen Fredrickson Joe Parrish Chris Urmson 《Canadian Metallurgical Quarterly》2001,14(2):59-64
This paper profiles research relating to the robotic assembly, inspection, and maintenance of space solar-power facilities. Free-flying robots, fixed-base manipulators, and attached mobile manipulators are examined, the technical challenges facing them are outlined, and their roles in the construction process are illuminated. Themes include autonomous materials delivery, warehousing, large-scale payload handling and mating, payload attachment in confined spaces, and inspection. Research has addressed a fraction of the technologies needed to perform reliable autonomous assembly, inspection, and maintenance. Areas in need of further development are examined and potential research is outlined. Current technology cannot fulfill the requirements of orbital construction. The research and development needed can be completed in the near future, and substantive assembly inspection and maintenance can be achieved. 相似文献
102.
Feehan Michael; Stanton Warren R.; McGee Rob; Silva Phil A.; Moffitt Terrie E. 《Canadian Metallurgical Quarterly》1990,99(2):198
Results of recent research suggests an association between left lateral preference and delinquent behavior. In this study the lateral preferences of 881 seven-year-old children were determined using behavioral indicators of hand and foot use. Mixed-handedness was associated with parent-reported problem behavior scores and self-reported delinquency scores at ages 13 and 15. However, preference for left hand and foot use was found to be unrelated to the delinquency measures. The distribution of lateral preferences in an identified delinquent group was not significantly different from the distribution in the sample remainder. The lack of an association between left preference and delinquency may be accounted for by an increased cultural acceptance of individual preference. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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105.
Two processes have been hypothesized to underlie improvement in perception: attunement and calibration. These processes were examined in a dynamic touch paradigm in which participants were asked to report the lengths of unseen, wielded rods differing in length, diameter, and material. Two experiments addressed whether feedback informs about the need for reattunement and recalibration. Feedback indicating actual length induced both recalibration and reattunement. Recalibration did not occur when feedback indicated only whether 2 rods were of the same length or of different lengths. Such feedback, however, did induce reattunement. These results suggest that attunement and calibration are dissociable processes and that feedback informs which is needed. The observed change in variable use has implications also for research on what mechanical variables underlie length perception by dynamic touch. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
Short tests containing at most 15 items are used in clinical and health psychology, medicine, and psychiatry for making decisions about patients. Because short tests have large measurement error, the authors ask whether they are reliable enough for classifying patients into a treatment and a nontreatment group. For a given certainty level, proportions of correct classifications were computed for varying test length, cut-scores, item scoring, and choices of item parameters. Short tests were found to classify at most 50% of a group consistently. Results were much better for tests containing 20 or 40 items. Small differences were found between dichotomous and polytomous (5 ordered scores) items. It is recommended that short tests for high-stakes decision making be used in combination with other information so as to increase reliability and classification consistency. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
We study the scheduling problem of minimizing the maximum starting time on-line. The goal is to minimize the last time that a job starts. We show that while the greedy algorithm has a competitive ratio of Θ (log m), we can give a constant competitive algorithm for this problem. We also show that the greedy algorithm is optimal for resource augmentation in the sense that it requires 2m − 1 machines to have a competitive ratio of 1, whereas no algorithm can achieve this with 2m − 2 machines. 相似文献
108.
Luca Aceto Wan Fokkink Rob van Glabbeek Anna Inglfsdttir 《Information and Computation》2004,191(2):203
This paper studies nested simulation and nested trace semantics over the language BCCSP, a basic formalism to express finite process behaviour. It is shown that none of these semantics affords finite (in)equational axiomatizations over BCCSP. In particular, for each of the nested semantics studied in this paper, the collection of sound, closed (in)equations over a singleton action set is not finitely based. 相似文献
109.
JC Healy S Halligan RH Reznek S Watson CI Bartram MA Kamm RK Phillips P Armstrong 《Canadian Metallurgical Quarterly》1997,84(11):1555-1558
BACKGROUND: Evacuation proctography and measurements of anorectal physiology are frequently used to clarify the pathophysiology of obstructed defaecation. In some patients these tests are normal, despite convincing clinical evidence of defaecatory difficulty. The aim of this study was to determine whether magnetic resonance imaging (MRI) could reveal pelvic floor abnormality in patients with obstructed defaecation. METHODS: Eleven women with obstructed defaecation, in whom evacuation proctography and anorectal physiology were normal, were examined by MRI, using a fast gradient echo sequence. Measurements of pelvic visceral and muscular descent were taken at rest and during straining, and compared with those obtained from 13 asymptomatic volunteers. RESULTS: Patients with obstructed defaecation had significantly greater pelvic visceral descent (P < 0.05), levator muscle descent (P = 0.04), levator plate angle change (P = 0.003) and increase in the area of the pelvic floor hiatus (P = 0.0002) than asymptomatic volunteers. CONCLUSION: MRI demonstrated marked pelvic visceral and levator muscle descent in women with obstructed defaecation, despite normal evacuation proctography and anorectal physiology. MRI should be considered if these examinations have been normal. 相似文献
110.
Eijsink Vincent G.H.; Vriend Gerrit; van den Burg Bertus; van der Zee J.Rob; Veltman Oene R.; Stulp Ben K.; Venema Gerard 《Protein engineering, design & selection : PEDS》1992,5(2):157-163
A 10 residue ß-hairpin, which is characteristic ofthermostable Bacillus neutral proteases, was engineered intothe thermolabile neutral protease of Bacillus subtilis. Therecipient enzyme remained fully active after introduction ofthe loop. However, the mutant protein exhibited autocatalyticnicking and a 0.4°C decrease in thermostability. Two additionalpoint mutations designed to improve the interactions betweenthe enzyme surface and the introduced ß-hairpin resultedin reduced nicking and increased thermostability. After theintroduction of both additional mutations in the loopcontainingmutant, nicking was largely prevented and an increase in thermostabilityof 1.1°C was achieved. 相似文献