13,033 research outputs found
Aligning and positioning device Patent
Description of device for aligning stacked sheets of paper for repetitive cuttin
Cross Recurrence Plot Based Synchronization of Time Series
The method of recurrence plots is extended to the cross recurrence plots
(CRP), which among others enables the study of synchronization or time
differences in two time series. This is emphasized in a distorted main diagonal
in the cross recurrence plot, the line of synchronization (LOS). A
non-parametrical fit of this LOS can be used to rescale the time axis of the
two data series (whereby one of it is e.g. compressed or stretched) so that
they are synchronized. An application of this method to geophysical sediment
core data illustrates its suitability for real data. The rock magnetic data of
two different sediment cores from the Makarov Basin can be adjusted to each
other by using this method, so that they are comparable.Comment: Nonlinear Processes in Geophysics, 9, 2002, in pres
On the selection of secondary indices in relational databases
An important problem in the physical design of databases is the selection of secondary indices. In general, this problem cannot be solved in an optimal way due to the complexity of the selection process. Often use is made of heuristics such as the well-known ADD and DROP algorithms. In this paper it will be shown that frequently used cost functions can be classified as super- or submodular functions. For these functions several mathematical properties have been derived which reduce the complexity of the index selection problem. These properties will be used to develop a tool for physical database design and also give a mathematical foundation for the success of the before-mentioned ADD and DROP algorithms
High reliability bond program using small diameter aluminum wire
The program was undertaken to characterize the performance of small diameter aluminum wire ultrasonically bonded to conductors commonly encountered in hybrid assemblies, and to recommend guidelines for improving this performance. Wire, 25.4, 38.1 and 50.8 um (1, 1.5 and 2 mil), was used with bonding metallization consisting of thick film gold, thin film gold and aluminum as well as conventional aluminum pads on semiconductor chips. The chief tool for evaluating the performance was the double bond pull test in conjunction with a 72 hour - 150 C heat soak and -65 C to +150 C thermal cycling. In practice the thermal cycling was found to have relatively little effect compared to the heat soak. Pull strength will decrease after heat soak as a result of annealing of the aluminum wire; when bonded to thick film gold, the pull strength decreased by about 50% (weakening of the bond interface was the major cause of the reduction). Bonds to thin film gold lost about 30 - 40% of their initial pull strenth; weakening of the wire itself at the bond heel was the predominant cause. Bonds to aluminum substrate metallization lost only about 22%. Bonds between thick and thin film gold substrate metallization and semiconductor chips substantiated the previous conclusions but also showed that in about 20 to 25% of the cases, bond interface failure occurred at the semiconductor chip
- …