OBSCURANT AND EMISSION CHARACTERISTICS OF THE SCREENING SMOKE COMPOSITIONS USED IN NAVAL SHIPS

2020 ◽  
pp. 108-117
Author(s):  
Toan
Keyword(s):  
Wavelength Range ◽  
Extinction Coefficient ◽  
Infrared Emission ◽  
The Other ◽  
Emission Characteristics ◽  
Red Phosphorus ◽  
Other Hand

Obscurant and optronic decoy compositions are the pyrotechnic formulations that are an effective way to protect naval ships from optical guided missile seekers. In this work, the obscurant characteristics (i.e. the transmittance and the extinction coefficient) and the infrared emission characteristics (i.e. the infrared emission distribution and the radiance) of the obscurant and optronic decoy compositions were described. The results showed that the obscurant cloud made from the mixture of red phosphorus, Ba(NO3)2 and Viton rubber has a low transmittance, high extinction coefficient with 1.06 µm laser and strong infrared emission in the wavelength range of 8.0 to 14.0 µm. On the other hand, the infrared emission radiance (in the wavelength range of 2.5 to 5.0 µm) of the optronic decoy composition based on Mg-Al, hexachloroethane and Viton rubber reaches maximum values (i.e. 17.77E-3 W.cm-2.Sr-1) at about 17 wt% Mg-Al. Finally, the above obscurant and optronic decoy compositions can be used combination in naval ships against the anti-ship missile.

Absorption and index of refraction for the modeling of InGaAsP/InP photonic devices

1993 ◽  
Vol 71 (9-10) ◽  
pp. 410-416 ◽  
Author(s):  
B. Reid ◽  
R. Maciejko ◽  
A. Champagne
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Wavelength Range ◽  
Photonic Devices ◽  
Index Of Refraction ◽  
The Other ◽  
Other Hand ◽  
Lattice Matched

Methods for modeling, over an extended practical wavelength range, the index of refraction and the absorption in lattice-matched InGaAsP/InP-based photonic devices are reviewed, completed, and clarified. Carrier-induced effects on the optical properties are given special attention. For the index of refraction, the method gives results within 1% of the experimental ones. On the other hand, the results for absorption are more difficult to compare owing to the lack of experimental data.

OPTICAL PROPERTIES OF FUNCTIONALIZED POLYTHIOPHENES

2005 ◽  
Vol 19 (32) ◽  
pp. 4645-4676 ◽  
Author(s):  
N. SOMANATHAN ◽  
S. RADHAKRISHNAN
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Functional Groups ◽  
Thiophene Ring ◽  
Point Of View ◽  
The Other ◽  
Emission Characteristics ◽  
Polymeric Structure ◽  
Other Hand

This review focuses on the interrelation between the influences of polymeric structure on the optical properties of polythiophene — a versatile polymer for opto-electronic applications. From the application's point of view, the polymer should either be melt- or solution-processible. Functionalization of polythiophenes really helps for the above. On the other hand, the functionalization at the 3 and/or 4 position of the thiophene ring modifies the band gap of the polymer, which in turn, modifies photo absorption, photo- and electro-emission characteristics of polythiophenes. The present work reviews the influence of the optical properties of polythiophene on the different functional groups present in the thiophene ring.

scholarly journals Validation of UV-visible aerosol optical thickness retrieved from spectroradiometer measurements

2008 ◽  
Vol 8 (16) ◽  
pp. 4655-4663 ◽  
Author(s):  
C. Brogniez ◽  
V. Buchard ◽  
F. Auriol
Keyword(s):  
Correlation Coefficient ◽  
Wavelength Range ◽  
Optical Thickness ◽  
Regression Line ◽  
Aerosol Optical Thickness ◽  
The Other ◽  
Other Hand ◽  
Uv Visible ◽  
Nm Range ◽  
Good Agreement

Abstract. Global and diffuse UV-visible solar irradiances are routinely measured since 2003 with a spectroradiometer operated by the Laboratoire d'Optique Atmosphérique (LOA) located in Villeneuve d'Ascq, France. The analysis of the direct irradiance derived by cloudless conditions enables retrieving the aerosol optical thickness (AOT) spectrum in the 330–450 nm range. The site hosts also sunphotometers from the AERONET/PHOTONS network performing routinely measurements of the AOT at several wavelengths. On one hand, comparisons between the spectroradiometer and the sunphotometer AOT at 440 nm as well as, when available, at 340 and 380 nm, show good agreement: in 2003–2005 at 440 nm the correlation coefficient, the slope and the intercept of the regression line are [0.97, 0.95, 0.025], and in 2006 at 440, 380 and 340 nm they are [0.97, 1.00, −0.013], [0.97, 0.98, −0.007], and [0.98, 0.98, −0.002] respectively. On the other hand, the AOT's spectral variations have been compared using the Angström exponents derived from AOT data at 340 and 440 nm for both instruments. The comparisons show that this parameter is difficult to retrieve accurately due to the small wavelength range and due to the weak AOT values. Thus, AOT derived at wavelengths outside the spectroradiometer range by means of an extrapolation using the Angström parameter would have large uncertainties, whereas spectroradiometer's spectral AOT could be used for direct validation of other AOT, such as those provided by satellite instruments.

scholarly journals Validation of UV-visible aerosol optical thickness retrieved from spectroradiometer measurements

2008 ◽  
Vol 8 (1) ◽  
pp. 3895-3919 ◽  
Author(s):  
C. Brogniez ◽  
V. Buchard ◽  
F. Auriol
Keyword(s):  
Wavelength Range ◽  
Optical Thickness ◽  
Aerosol Optical Thickness ◽  
The Other ◽  
Other Hand ◽  
Uv Visible ◽  
Nm Range ◽  
Good Agreement ◽  
Satellite Instruments

Abstract. Global and diffuse UV-visible solar irradiances are routinely measured since 2003 with a spectroradiometer operated by the Laboratoire d'Optique Atmosphérique (LOA) located in Villeneuve d'Ascq, France. The analysis of the direct irradiance derived by cloudless conditions enables retrieving the aerosol optical thickness (AOT) spectrum in the 330–450 nm range. The site hosts also sunphotometers from the AERONET/PHOTONS network performing routinely measurements of the AOT at several wavelengths. On one hand, comparisons between the spectroradiometer and the sunphotometer AOT at 440 nm as well as, when available, at 340 and 380 nm, show good agreement. On the other hand, the AOT's spectral variations have been compared using the Angström exponents derived from AOT data at 340 and 440 nm for both instruments. The comparisons show that this parameter is difficult to retrieve accurately due to the small wavelength range and due to the weak AOT values. Thus, AOT derived at wavelengths outside the spectroradiometer range by means of an extrapolation using the Angström parameter would be of poor value, whereas, spectroradiometer's spectral AOT could be used for direct validation of other AOT, such as those provided by satellite instruments.

scholarly journals Effects of Mg Al Alloy Powder on the Combustion and Infrared Emission Characteristics of the Mg Al PTFE Viton Composition

2020 ◽  
Vol 70 (6) ◽  
pp. 590-595
Author(s):  
Toan Nguyen Trung ◽  
Nhung Nguyen Thi Cam
Keyword(s):  
Particle Size ◽  
Burning Rate ◽  
Alloy Powder ◽  
Infrared Emission ◽  
The Other ◽  
Al Alloy ◽  
Emission Characteristics ◽  
Infrared Radiance ◽  
Alloy Particles ◽  
Pyrotechnic Composition

Metal-Fluorocarbon compositions are the pyrotechnic formulations which have been widely used in infrared decoy flares to protect aerial targets from infrared guide missile seekers. In this work, the effect of Mg-Al alloy powder (i.e. the particle size and the content) on the combustion and the infrared emission characteristics (i.e. the infrared emission distribution and the infrared radiance) of the pyrotechnic composition based on Mg-Al alloy, polytetrafluoroethylene (PTFE) and Viton rubber are described. The results show that the high burning rate (with the values of 4.0 mm.s-1 to 10.0 mm.s-1, depend on the compression density) of this composition is achieved with a high content of Mg-Al alloy or when using fine Mg-Al alloy particles as well as coarse PTFE particles. On the other hand, the infrared emission radiance (in the wavelength range of 2.5 μm to 5.0 μm) of Mg-Al/PTFE/Viton composition reaches maximum values (i.e. 17.7 W.cm-2.Sr-1 and 21.0 W.cm-2.Sr-1 with the size of Mg-Al particles are 20 μm and 120 μm, respectively) at 60 wt% Mg-Al alloy. Finally, the Mg-Al/PTFE/Viton composition has a similar combustion and emission characteristics as the Mg/PTFE/Viton composition.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

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