Cross-entropy method - Revision history

89.103.14.101: /* Estimation via importance sampling */ typo

2015-01-06T00:13:53Z

Estimation via importance sampling: typo

← Older revision		Revision as of 02:13, 6 January 2015
Line 1:		Line 1:
	~~{{Refimprove\|date=December 2008}}~~		Let me initial start by introducing myself. My name is Boyd Butts even though it is not the title on my beginning certificate. One of the very best issues in the world for me is to do aerobics and now I'm attempting to make money with it. South Dakota is where me and my husband reside. He used to be unemployed but now he is a meter reader.<br><br>Review my weblog; [http://citymama.com.ua/profile_info.php?ID=38588 citymama.com.ua]
	~~The '''Bond albedo''', named after the American astronomer [[George Phillips Bond]] (1825–1865), who originally proposed~~ it, is the ~~fraction of [[power (physics)\|power]] in the total [[electromagnetic radiation]] incident~~ on ~~an astronomical body that is scattered back out into space~~.

	~~Because the Bond albedo accounts for all~~ of the light scattered from a body at all [[wavelength]]s and all [[Phase angle (astronomy)\|phase angles]], it is a necessary quantity for determining how much energy a body absorbs. This, in turn, is crucial for determining the [[equilibrium temperature]] of a body.

	~~Because bodies~~ in the ~~outer Solar System are always observed at very low phase angles from the Earth, the only reliable data~~ for ~~measuring their Bond albedo comes from spacecraft.~~

	~~==Phase integral==~~
	~~The Bond albedo (''A'')~~ is ~~related~~ to ~~the [[geometric albedo]] (''p'') by the expression~~

	~~::<math>~~
	~~A = p q \frac{}{}~~
	~~</math>~~

	~~where ''q'' is termed the ''phase integral''~~ and ~~is given in terms of the directional scattered flux ''~~I'~~'(''α'') into phase angle α (averaged over all wavelengths and azimuthal angles) as~~

	~~::<math>~~
	~~q = 2\int_0^\pi \frac{I(\alpha)}{I(0)} \sin \alpha \, d\alpha~~.
	~~</math>~~

	~~The phase [[angle]] α~~ is ~~the angle between the source of the radiation (usually the Sun) and the observing direction,~~ and ~~varies from zero for light scattered back towards the source, to 180° for observations looking towards the source~~. ~~For example, during opposition or looking at the full moon, α is very small, while backlit objects or the new moon have α close~~ to ~~180°.~~

	~~==Examples==~~
	~~The Bond albedo~~ is a value strictly between 0 and 1, as it includes all possible scattered light (but not radiation from the body itself). This is in contrast to other definitions of [[albedo]] such as the geometric albedo, which can be above 1. In general, though, the Bond albedo may be greater or smaller than the geometric albedo, depending on surface and atmospheric properties of the body in question.

	~~Some examples:<ref>[http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/albedo~~.~~html Albedo of the Earth~~<~~!-- Bot generated title --~~>]<~~/ref~~>
	~~{{astronomical albedo table}}~~

	~~==See also==~~
	* [[Albedo]]
	*[[~~Geometric albedo]]~~

	~~==References==~~
	~~<references>~~
	~~<ref name="earth_fact_sheet">{{cite web\|last1=Williams\|first1=David R.\|date=2004-09-01\|url=~~http://~~nssdc~~.~~gsfc.nasa~~.~~gov/planetary/factsheet~~/~~earthfact~~.~~html\|title=Earth Fact Sheet\|publisher=NASA\|accessdate=2010-08-09}}</ref>~~
	~~</references>~~

	~~==External links=~~=
	* [http://web.archive.org/web/20090413042346/http://jeff.medkeff.com~~/astro/lunar/obs_tech/albedo~~.~~htm discussion of Lunar albedo]~~

	~~[[Category:Electromagnetic radiation]]~~
	~~[[Category:Astrophysics]]~~
	~~[[Category:Radiometry]]~~
	~~[[Category:Scattering, absorption and radiative transfer (optics)]~~]

87.61.143.120: Same order of logical expression in code and in comment

2013-12-02T20:28:51Z

Same order of logical expression in code and in comment

← Older revision		Revision as of 22:28, 2 December 2013
Line 1:		Line 1:
	~~Hello~~ and ~~welcome~~. ~~My title~~ is ~~Numbers Wunder~~. ~~California~~ is where ~~her house~~ is ~~but she needs~~ to ~~move because of her family members~~. ~~What I adore doing~~ is to ~~gather badges~~ but ~~I've been taking~~ on ~~new issues recently~~. ~~For many years I've been working as a payroll clerk~~.<br><br>~~Have a look at my~~ web-~~site~~ :~~: std testing at home~~ - [http://~~raybana~~.~~com~~/~~chat~~/pg/~~groups~~/~~174883~~/~~solid-advice-for-dealing-with-a-candida~~/ ~~Read More Here~~],		{{Refimprove\|date=December 2008}}
			The '''Bond albedo''', named after the American astronomer [[George Phillips Bond]] (1825–1865), who originally proposed it, is the fraction of [[power (physics)\|power]] in the total [[electromagnetic radiation]] incident on an astronomical body that is scattered back out into space.

			Because the Bond albedo accounts for all of the light scattered from a body at all [[wavelength]]s and all [[Phase angle (astronomy)\|phase angles]], it is a necessary quantity for determining how much energy a body absorbs. This, in turn, is crucial for determining the [[equilibrium temperature]] of a body.

			Because bodies in the outer Solar System are always observed at very low phase angles from the Earth, the only reliable data for measuring their Bond albedo comes from spacecraft.

			==Phase integral==
			The Bond albedo (''A'') is related to the [[geometric albedo]] (''p'') by the expression

			::<math>
			A = p q \frac{}{}
			</math>

			where ''q'' is termed the ''phase integral'' and is given in terms of the directional scattered flux ''I''(''α'') into phase angle α (averaged over all wavelengths and azimuthal angles) as

			::<math>
			q = 2\int_0^\pi \frac{I(\alpha)}{I(0)} \sin \alpha \, d\alpha.
			</math>

			The phase [[angle]] α is the angle between the source of the radiation (usually the Sun) and the observing direction, and varies from zero for light scattered back towards the source, to 180° for observations looking towards the source. For example, during opposition or looking at the full moon, α is very small, while backlit objects or the new moon have α close to 180°.

			==Examples==
			The Bond albedo is a value strictly between 0 and 1, as it includes all possible scattered light (but not radiation from the body itself). This is in contrast to other definitions of [[albedo]] such as the geometric albedo, which can be above 1. In general, though, the Bond albedo may be greater or smaller than the geometric albedo, depending on surface and atmospheric properties of the body in question.

			Some examples:<ref>[http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/albedo.html Albedo of the Earth<!-- Bot generated title -->]</ref>
			{{astronomical albedo table}}

			==See also==
			* [[Albedo]]
			*[[Geometric albedo]]

			==References==
			<references>
			<ref name="earth_fact_sheet">{{cite web\|last1=Williams\|first1=David R.\|date=2004-09-01\|url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html\|title=Earth Fact Sheet\|publisher=NASA\|accessdate=2010-08-09}}</ref>
			</references>

			==External links==
			* [http://web.archive.org/web/20090413042346/http://jeff.medkeff.com/astro/lunar/obs_tech/albedo.htm discussion of Lunar albedo]

			[[Category:Electromagnetic radiation]]
			[[Category:Astrophysics]]
			[[Category:Radiometry]]
			[[Category:Scattering, absorption and radiative transfer (optics)]]

en>Shuroo at 08:17, 8 June 2012

2012-06-08T08:17:05Z

New page

Hello and welcome. My title is Numbers Wunder. California is where her house is but she needs to move because of her family members. What I adore doing is to gather badges but I've been taking on new issues recently. For many years I've been working as a payroll clerk.<br><br>Have a look at my web-site :: std testing at home - [http://raybana.com/chat/pg/groups/174883/solid-advice-for-dealing-with-a-candida/ Read More Here],