Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy

Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS), coherent Raman spectroscopy, and terahertz (THz) spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications

In Evangelium secundum Matthaeum, Marcum, et Lucam commentarii ex ecclesiasticis scriptoribus collecti novae glossae ordinariae specimen, donec meliora Dominus.

GLN-1908Adams, Cambridge, B 1818, S 1817Bibelsammlung Stuttgart, D 617CDM, p. 22Collet, Montbrison, n° 139Drummond, Aberdeen, n° 1574Palatina, n° 5267Seebass, Osiandrica, n° 24.10Shaw, Cathedral Libr., 2, B 1642 (2e part.), E 622STC Edinburgh, p. 5

Analysis of Time-Resolved Shearographic Methods with Controlled Thermal Stressing

Electronic shearographic interferometry is a nondestructive evaluation (NDE) technique in which qualitative detection of subsurface defects is readily achieved. In both industrial and laboratory environments, various full field stressing methods, including vibration, vacuum, thermal and mechanical loading, have been employed to produce characteristic deformations which can be monitored shearographically [1,2]. However, quantitative measurements of parameters such as defect depth are difficult to make with these techniques. This paper presents the results of using controlled thermal stressing with shearography in an effort to expand the quantitative capabilities of the technique. The use of controlled thermal-stressing allows a totally noncontact inspection technique with a large standoff distance to monitor the time-dependent deformations of test specimens. Typically laser power levels of tens of milliWatts are sufficient to generate measurable deformations.</p

Comparison of Ultrasonic, Microwave, and Photothermal Imaging of Defective Graphite-Epoxy Composite Panels

We compare results of ultrasonic, microwave, and thermal imaging of graphite-epoxy composite panels with artificial defect structures

Development of the Variable Emittance Thermal Suite for the Space Technology 5 Microsatellite

The advent of very small satellites, such as nano and microsatellites, logically leads to a requirement for smaller thermal control subsystems. In addition, the thermal control needs of the smaller spacecraft/instrument may well be different from more traditional situations. For example, power for traditional heaters may be very limited or unavailable, mass allocations may be severely limited, and fleets of nano/microsatellites will require a generic thermal design as the cost of unique designs will be prohibitive. Some applications may require significantly increased power levels while others may require extremely low heat loss for extended periods. Small spacecraft will have low thermal capacitance thus subjecting them to large temperature swings when either the heat generation rate changes or the thermal sink temperature changes. This situation, combined with the need for tighter temperature control, will present a challenging situation during transient operation. The use of "off-the-shelf" commercial spacecraft buses for science instruments will also present challenges. Older thermal technology, such as heaters, thermostats, and heat pipes, will almost certainly not be sufficient to meet the requirements of these new spacecraft/instruments. They are generally too heavy, not scalable to very small sizes, and may consume inordinate amounts of power. Hence there is a strong driver to develop new technology to meet these emerging needs. Variable emittance coatings offer an exciting alternative to traditional control methodologies and are one of the technologies that will be flown on Space Technology 5, a mission of three microsatellites designed to validate "enabling" technologies. Several studies have identified variable emittance coatings as applicable to a wide range of spacecraft, and to potentially offer substantial savings in mass and/or power over traditional approaches. This paper discusses the development of the variable emittance thermal suite for ST-5. More specifically, it provides a description of and the infusion and validation plans for the variable emittance coatings

Measurement of Titan's surface permittivity with the DraGMet/DIEL sensor on Dragonfly

International audienc

Towards an English School Theory of Hegemony

English School (ES) writers have never developed a systematic account of hegemony, and most set out with assumptions that are `antihegemonial'. The writings of Hedley Bull, in particular, appeared to reject any notion of a legitimate hegemony. However, a social theory of hegemony that emphasizes its consensual nature does appear consistent with other ES positions, particularly on the role of the Great Powers. This article excavates an ES theory of hegemony. It develops the argument for hegemony as a potential institution of international society, by analogy with the role of the Great Powers, and by extension of other ES principles. This stresses not just the material power of the Great Powers, but their degree of social recognition. Accordingly, it suggests that such a view of hegemony is no more paradoxical than, say, ES acceptance of war as a similar institution. This fills a major void in ES theory which otherwise has nothing of interest to say about international order in conditions of primacy