Identifying Dark Web clusters with temporal coherence analysis

2011 ◽  
Author(s):  
Christopher C. Yang ◽  
Xuning Tang ◽  
Xiajing Gong
Keyword(s):  
Temporal Coherence ◽  
Coherence Analysis ◽  
Web Clusters ◽  
Dark Web

Defect Detection of Flip Chip Solder Bumps Through Local Temporal Coherence Analysis of Laser Ultrasound Signals

2007 ◽  
Author(s):  
Jin Yang ◽  
Charles Ume
Keyword(s):  
Defect Detection ◽  
Flip Chip ◽  
Solder Bump ◽  
Temporal Coherence ◽  
Coherence Analysis ◽  
Laser Ultrasound ◽  
Surface Mount ◽  
Flip Chips ◽  
Solder Bumps ◽  
Ultrasound Signals

Microelectronics packaging technology has evolved from through-hole and bulk configuration to surface-mount and small-profile ones. In surface mount packaging, such as flip chips, chip scale packages (CSP), and ball grid arrays (BGA), chips/packages are attached to the substrates or printed wiring boards (PWB) using solder bump interconnections. Solder bumps, which are hidden between the device and the substrate/board, are no longer visible for inspection. A novel solder bump inspection system has been developed using laser ultrasound and interferometric techniques. This system has been successfully applied to detect solder bump defects including missing, misaligned, open, and cracked solder bumps in flip chips, and chip scale packages. This system uses a pulsed Nd:YAG laser to induce ultrasound in the thermoelastic regime and the transient out-of-plane displacement response on the device surface is measured using the interferometric technique. In this paper, local temporal coherence (LTC) analysis of laser ultrasound signals is presented and compared to previous signal processing methods, including Error Ratio and Correlation Coefficient. The results show that local temporal coherence analysis increases measurement sensitivity for inspecting solder bumps in packaged electronic devices. Laser ultrasound inspection results are also compared with X-ray and C-mode Scanning Acoustic Microscopy (CSAM) results. In particular, this paper discusses defect detection for a 6.35mm×6.35mm×0.6mm PB18 flip chip and a flip chip (SiMAF) with 24 lead-free solder bumps. These two flip chip specimens are both non-underfilled.

First demonstration of a temporal coherence analysis through a parametric interferometer

2008 ◽  
Vol 281 (10) ◽  
pp. 2722-2726 ◽  
Author(s):  
L. Del Rio ◽  
M. Ribiere ◽  
L. Delage ◽  
F. Reynaud
Keyword(s):  
Temporal Coherence ◽  
Coherence Analysis

scholarly journals Effect of spectral sampling on the temporal coherence analysis of a broadband source in a SFG interferometer

2015 ◽  
Vol 23 (20) ◽  
pp. 25450 ◽  
Author(s):  
Pascaline Darré ◽  
Ludovic Szemendera ◽  
Ludovic Grossard ◽  
Laurent Delage ◽  
François Reynaud
Keyword(s):  
Temporal Coherence ◽  
Coherence Analysis ◽  
Spectral Sampling

Principle and practice of high-resolution imaging with a field-emission TEM

1992 ◽  
Vol 50 (1) ◽  
pp. 138-139
Author(s):  
Max T. Otten ◽  
Wim M.J. Coene
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Incidence Angle ◽  
Temporal Coherence ◽  
Energy Spread ◽  
High Resolution Imaging ◽  
Major Improvement ◽  
High Resolution Images ◽  
Resolution Imaging

High-resolution imaging with a LaB6 instrument is limited by the spatial and temporal coherence, with little contrast remaining beyond the point resolution. A Field Emission Gun (FEG) reduces the incidence angle by a factor 5 to 10 and the energy spread by 2 to 3. Since the incidence angle is the dominant limitation for LaB6 the FEG provides a major improvement in contrast transfer, reducing the information limit to roughly one half of the point resolution. The strong improvement, predicted from high-resolution theory, can be seen readily in diffractograms (Fig. 1) and high-resolution images (Fig. 2). Even if the information in the image is limited deliberately to the point resolution by using an objective aperture, the improved contrast transfer close to the point resolution (Fig. 1) is already worthwhile.

The elementary forms of digital culture. Knowledge, connections and sociality

2020 ◽  
pp. 316-328
Author(s):  
Vincenzo Susca
Keyword(s):  
Public Opinion ◽  
Daily Life ◽  
Digital Culture ◽  
Social Boundaries ◽  
Public Spheres ◽  
The Public ◽  
Nation States ◽  
The Senses ◽  
Point Of Intersection ◽  
Dark Web

Contemporary communicative platforms welcome and accelerate a socio-anthropological mutation in which public opinion (Habermas, 1995) based on rational individuals and alphabetic culture gives way to a public emotion whose emotion, empathy and sociality are the bases, where it is no longer the reason that directs the senses but the senses that begin to think. The public spheres that are elaborated in this way can only be disjunctive (Appadurai, 2001), since they are motivated by the desire to transgress the identity, political and social boundaries where they have been elevated and restricted. The more the daily life, in its local intension and its global extension, rests on itself and frees itself from projections or infatuations towards transcendent and distant orders, the more the modern territory is shaken by the forces that cross it and pierce it. non-stop. The widespread disobedience characterizing a significant part of the cultural events that take place in cyberspace - dark web, web porn, copyright infringement, trolls, even irreverent ... - reveals the anomic nature of the societal subjectivity that emerges from the point of intersection between technology and naked life. Behind each of these offenses is the affirmation of the obsolescence of the principles on which much of the modern nation-states and their rights have been based. Each situation in which a tribe, cloud, group or network blends in a state of ecstasy or communion around shared communications, symbols and imaginations, all that surrounds it, in material, social or ideological terms, fades away. in the air, being isolated by the power of a bubble that in itself generates culture, rooting, identification: transpolitic to inhabit

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