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排序方式: 共有193条查询结果,搜索用时 31 毫秒
1.
A dyeing profile for a range of reactive dyes suitable for application to cellulosic knitwear is defined. Such a profile shows good level-dyeing, reproducibility and fastness properties together with potential for simplified dyeing processes. 相似文献
2.
Frequency Dependence of Fatigue Life and Internal Heating of a Fiber-Reinforced/Ceramic-Matrix Composite 总被引:1,自引:0,他引:1
John W. Holmes Xin Wu Bent F. Sørensen 《Journal of the American Ceramic Society》1994,77(12):3284-3286
The influence of loading frequency on the fatigue life and internal (frictional) heating of unidirectional SiC-fiber/ calcium aluminosilicate-matrix composites was investigated at room temperature. Specimens were subjected to tension–tension fatigue at sinusoidal loading frequencies from 25 to 350 Hz and maximum fatigue stresses of 180 to 240 MPa. The key findings of the study were that (1) fatigue life decreased sharply as the loading frequency was increased, (2) for all loading frequencies, fatigue failures occurred at stress levels that were significantly below the monotonic proportional limit stress of ∼285 MPa, and (3) pronounced internal heating occurred during fatigue, with the surface temperature of the fatigue specimens increasing by 160 K during 350-Hz fatigue at a peak stress of 240 MPa. 相似文献
3.
Joseph Eng Jr. Bernd Frühberger Jingguang G. Chen Brian E. Bent 《Catalysis Letters》1998,54(3):133-140
The thermal decomposition pathways of isobutene and 1-butene on both Mo(110) and 4 × 4-C/Mo(110) surfaces have been studied using high-resolution electron energy loss spectroscopy (HREELS) in order to highlight the substantially different activities of these two surfaces towards the cleavage of C–H and C–C bonds. On clean Mo(110), the CH2 group of isobutene decomposes upon heating to 150 K, producing either a /-bonded isobutenylidene [(CH3)2CCH] species or a 1,1-di-/-bonded isobutenyl [(CH3)2CC] species. Upon further heating, extensive C–H bond scission occurs to form hydrocarbon fragments which do not contain CH3 or CH2 groups, but appear to have largely intact carbon skeletons. By contrast, isobutene is molecularly adsorbed on the carbide-modified surface at 150 K. Further heating produces isobutylidyne [(CH3)2HCC] by 300 K, which subsequently decomposes via C–C bond scission to generate surface methyl groups. The different activation sequence of the C–H and C–C bonds of isobutene on clean and carbide-modified Mo(110) surfaces is also qualitatively confirmed by comparative studies of 1-butene on the two surfaces. 相似文献
4.
The disproportionation ofn-butane (and of isobutane) was catalyzed by sulfated zirconium oxide containing 1.5 wt% Fe, 0.5 wt% Mn, and 4.0 wt% sulfate at 2.0 atm and temperatures in the range of 30–60C. The reaction accompanies isomerization, which under some conditions is as much as one or two orders of magnitude faster than disproportionation. The conversion to each of the products increased with time on stream in a flow reactor, and then declined. The time on stream for maximum conversion was the same for each product. The results suggest that the disproportionation and isomerization reactions proceed through a common C8 intermediate. Rates of the disproportionation reaction were determined at the time on stream corresponding to the maximum conversion at each temperature; for example, the rate of conversion ofn-butane into isopentane at 60C with ann-butane partial pressure of 0.58 atm was about 1×10–7 mol/(g of catalyst s). 相似文献
5.
Moira Bent 《New Review of Information Networking》2013,18(2):81-99
This article uses data from research conducted in the course of writing a book on the needs, wants and characteristics of researchers to examine how researchers view themselves and the research process. As a result of this, the Seven Ages of Research model was developed which categorises a researcher's learning life into a series of discrete stages. The article explores learning needs relevant to each age in the learning life and links them to the development of information literacy. The authors explore the polarisation that exists between what researchers think research is about and what they believe the library can offer them, and suggest that information literacy needs to be seen as involving a change in understanding of, and attitude to, the world of information, as well as the nature of those information needs. Finally, they explore the librarian's role in an e-environment which has changed the way researchers work and identify some of the challenges facing library and information services professionals in the future in supporting researchers throughout their learning lives. 相似文献
6.
7.
This paper explores how theories of the planning fallacy and the outside view may be used to conduct quality control and due diligence in project management. First, a much-neglected issue in project management is identified, namely that the front-end estimates of costs and benefits – used in the business cases, cost–benefit analyses, and social and environmental impact assessments that typically support decisions on projects – are commonly significantly different from actual ex post costs and benefits, and are therefore poor predictors of the actual value and viability of projects. Second, it is discussed how Kahneman and Tversky's theories of the planning fallacy and the outside view may help explain and remedy this situation through quality control of decisions. Third, it is described what quality control and due diligence are in the context of project management, and an eight-step procedure is outlined for due diligence based on the outside view. Fourth, the procedure is tested on a real-life, multibillion-dollar project, organized as a public–private partnership. Finally, Akerlof and Shiller's recent discussion in economics of “firing the forecaster” is discussed together with its relevance to project management. In sum, the paper demonstrates the need, the theoretical basis, a practical methodology, and a real-life example for how to de-bias project management using quality control and due diligence based on the outside view. 相似文献
8.
Natasja Leth Bergholt Ari Demirel Michael Pedersen Ming Ding Tue Wenzel Kragstrup Thomas Andersen Bent Winding Deleuran Casper Bindzus Foldager 《International journal of molecular sciences》2022,23(1)
Systemic Intermittent Hypoxic Therapy (IHT) relies on the adaptive response to hypoxic stress. We investigated allogenic bone-graft resorption in the lumbar spine in 48 mice. The mice were exposed to IHT for 1 week before surgery or 1 week after surgery and compared with controls after 1 and 4 weeks. Complete graft resorption was observed in 33–36% of the animals in the control group, but none in the preoperative IHT group. Increased bone-graft volume was demonstrated by micro-computed tomography in the preoperative IHT group after 1 week (p = 0.03) while a non-significant difference was observed after 4 weeks (p = 0.12). There were no significant differences in the postoperative IHT group. Increased concentration of immune cells was localized in the graft area, and more positive tartrate-resistant acid phosphatase (TRAP) staining was found in controls compared with IHT allogenic bone grafts. Systemic IHT resulted in a significant increase of the major osteoclast inhibitor osteoprotegerin as well as osteogenic and angiogenic regulators Tgfbr3, Fst3l, Wisp1, and Vegfd. Inflammatory cytokines and receptor activator of nuclear factor kappa-B ligand (RANKL) stimulators IL-6, IL-17a, IL-17f, and IL-23r increased after 1 and 4 weeks, and serum RANKL expression remained constant while Ccl3 and Ccl5 decreased. We conclude that the adaptive response to IHT activates numerous pathways leading to inhibition of osteoclastic activity and inhibition of allogenic bone-graft resorption. 相似文献
9.
In the present paper the Natvig measures of component importance for repairable systems, and its extended version are analyzed for two three-component systems and a bridge system. The measures are also applied to an offshore oil and gas production system. According to the extended version of the Natvig measure a component is important if both by failing it strongly reduces the expected system uptime and by being repaired it strongly reduces the expected system downtime. The results include a study of how different distributions affect the ranking of the components. All numerical results are computed using discrete event simulation. In a companion paper [Huseby AB, Eide KA, Isaksen SL, Natvig B, Gåsemyr, J. Advanced discrete event simulation methods with application to importance measure estimation. 2009, submitted for publication] the advanced simulation methods needed in these calculations are described. 相似文献
10.
Future Scenarios: What are the Future Services and Applications? 总被引:1,自引:1,他引:0
Christian Kloch Jens Enevold Kristensen Bent Bilstrup 《Wireless Personal Communications》2010,53(3):315-327
With the change of paradigm within user-machine interaction, there is an increasing demand for seamless interoperability between
different technologies as well as more intuitive ways of utilizing the applications on the devices. This implies that the
underlying technologies must support the appropriate bandwidth, mobility and quality at the right cost in order for the end-user
to perceive the infrastructure appropriate for the services and corresponding applications of the future. In addition, it
is required that interoperability will be realized at the semantic level and not just the syntactical level. The purpose of
the paper is to present the authors’ thoughts of a new Information and Communication Technology paradigm and to highlight
what might have an impact on the realization/deployment of such a paradigm. 相似文献