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排序方式: 共有219条查询结果,搜索用时 15 毫秒
1.
Dishongh T. Basaran C. Cartwright A.N. Ying Zhao Heng Liu 《Advanced Packaging, IEEE Transactions on》2002,25(3):433-438
In this paper the influence of the temperature cycle time history profile on the fatigue life of ball grid array (BGA) solder joints is studied. Temperature time history in a Pentium processor laptop computer was measured for a three-month period by means of thermocouples placed inside the computer. In addition, Pentium BGA packages were subjected to industry standard temperature cycles and also to in-situ measured temperature cycle profiles. Inelastic strain accumulation in each solder joint during thermal cycling was measured by high sensitivity Moire interferometry technique. Results indicate that fatigue life of the solder joint is not independent of the temperature cycle profile used. Industry standard temperature cycle profile leads to conservative fatigue life observations by underestimating the actual number of cycles to failure. 相似文献
2.
Lyndsay A. Cartwright Sue Hayes Douglas C. Tozer Dan Clayton Mary-Ann Burns Dena Lewis Noah Gaetz Namrata Shrestha 《Journal of Great Lakes research》2021,47(2):273-282
Beneficial use impairments (BUIs) under the Great Lakes Water Quality Agreement identify environmental issues requiring remedial action within the Great Lakes Areas of Concern (AOCs). We conducted this study to support the assessment of the wildlife component of BUI 3: degradation of fish and wildlife populations. We compared bird and amphibian (frogs and toads) data from the Toronto and Region Conservation Authority’s Terrestrial Long-term Monitoring Program in the Toronto and Region AOC to an adjacent, but otherwise similar, reference watershed, Duffins Creek. Twelve of 13 targets were met within the AOC for forest bird, wetland bird, meadow bird and amphibian populations based on averages of mean annual values at sites within the AOC that were within two standard deviations of averages at sites in the Duffins Creek reference watershed between 2008 and 2017. Even though wildlife populations within the AOC were within the normal range of variability expected from a reference watershed, they were often at lower levels than within the Duffins Creek reference watershed. In addition, forest bird and amphibian populations were negatively affected by urbanization within the AOC and meadow bird indices declined. We conclude that while wildlife populations within the AOC currently meet targets for BUI 3, they continue to be negatively impacted by numerous stressors that are primarily related to past and ongoing urbanization. Thus, continued restoration of wildlife habitat and protection of existing habitat within the AOC is highly recommended. 相似文献
3.
We investigate the applicability of some novel spatial analysis techniques, developed for studies of astrophysical datasets, to the analysis of spatial point data in sedimentary basins. The techniques are evaluated and compared with standard methods using two test areas that contain large numbers of submarine pockmarks developed in distributed arrays. The familiar Ripley K and Voronoi tesselation techniques are used, and the results are then compared with those obtained using more novel techniques, the correlation length and minimal spanning tree. The correlation length technique is found to identify the precise distances at which clustering occurs more accurately, making a physical interpretation more clear than is possible using the Ripley K. The minimal spanning tree is found to be powerful at identifying the space-filling nature of the pockmark distribution, and has the advantage of being immune to edge effects. The use of these two novel techniques permits more information to be extracted from the datasets, and demonstrates clear statistically significant differences between them, which are not detectable using standard techniques. 相似文献
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6.
R. C. McCune W. T. Donlon O. O. Popoola E. L. Cartwright 《Journal of Thermal Spray Technology》2000,9(1):73-82
The cold gas-dynamic spray method produces coatings or deposits by introducing solid feedstock particles into a supersonic
gas stream developed through the use of a converging-diverging (de Laval) nozzle. The particles thus accelerated impact on
a substrate surface and develop into a dense deposit through a process believed to be similar to cold compaction. The work
reported here explores the internal nature and physical characteristics of copper deposits produced by the cold gas-dynamic
spray method using two vastly different starting powders: in one case, a “spongy” copper obtained by a direct-reduction process,
and in the second, a denser, more spheroidal particulate produced by gas atomization. Optical and electron microscopies (scanning
electron microscopy [SEM] and transmission electron microscopy [TEM]) were used to observe details of microstructure in the
feedstock particles and deposits. Young’s modulus and residual stress measurements for the deposits were obtained through
mechanical means, and measurements of hardness and electrical conductivity are reported. The internal structure of the cold-spray
deposit was influenced by the surface purity of the feedstock material. 相似文献
7.
We present a procedure using continuous wavelet transforms (CWTs) to extract the phase information from moiré interferograms. The relationship between precise ridge detection of the two-dimensional CWT magnitude map and accurate phase extraction is detailed. A cost function is introduced for the adaptive selection of the ridge, and a computationally inexpensive implementation of the cost function ridge detection algorithm is explored with dynamic programming optimization. The results of the proposed ridge detection algorithm on actual interferograms are illustrated. Moreover, the resulting extracted phase is demonstrated to be smooth and accurate. As a result, the sensitivity of the moiré interferometry method is improved to obtain a pixel-by-pixel in-plane strain distribution map. 相似文献
8.
D.K. Cartwright G. Manent P. Chenebault R. Sesuy E. De Nontaignac W.R. Diggle F.A. Johnson J.R. Findlay W. Glauner S. Jacobi H. Feuerstein M. Relic 《Nuclear Engineering and Design》1980,59(2):287-300
During the course of the ‘SCARABEE’ experimental programme, the primary objective of which was to study the fuel and thermohydraulic behaviour, fission-product concentration were measured by a number of techniques. These included delayed neutron monitoring, total gamma, gamma spectrometry, sodium sampling and analysis and gas sampling and analysis. This paper describes the methods used to evaluate the data from these measurements and discusses the results.The theoretical models for fission-product generation and release are described and compared with the experimental data, and a critical examination of the techniques and results leads to recommendations for improvements in methods for future experiments. Conclusions are drawn relating to fission-product behaviour in LMFBRs. It is recognized that the experiments do not model closely the power reactor situation, but it is argued that the results obtained, particularly from delayed-neutron measurements, do provide a useful pointer to the value of fission-product monitoring in limiting fuel damage from local fuel overheating faults. 相似文献
9.
P. W. Griffiths M. di Leo P. Cartwright P. C. Eames P. Yianoulis G. Leftheriotis B. Norton 《Solar Energy》1998,63(4):243-249
An indium-based seal augmented with an adhesive, developed to maintain a vacuum between two sheets of glass, avoids the high temperatures required to produce a seal in evacuated glazings to date. An experimentally-validated three-dimensional transient model has been used to predict heat transfer for an indium/adhesive sealed 1 m2 area evacuated window with a highly insulating frame. An overall heat loss coefficient of 0.9 W m−2 K−1, with a midplane value of 0.36 W m−2 K−1, can be achieved with 0.72 visible transmittance for two 6 mm panes separated by 0.2 mm diameter pillars 40 mm apart. The conduction through a 3 mm edge-seal was 1.14 W m−2 K−1. Detailed three-dimensional isothermal contour plots through the system are presented. 相似文献
10.