raketové motory

16. června 2011 v 11:35 | Marketta |  ->SCHOOL<-
Raketový motor je typ tepelného motoru, který pracuje na principu akce a reakce. Na rozdíl od většiny ostatních reaktivních motorů není závislý na atmosferickém kyslíku, a tak je schopen se pohybovat mimo atmosféru. Může být poháněn tuhými a kapalnými palivy.
Motor poháněný tuhými palivy (využívající tuhé pohonné látky tzv. TPL) je jednodušší. Je tvořen spalovací komorou a hnací tryskou. Skoro celá spalovací komora je naplněna palivem nebo směsí paliva a okysličovadla, které postupně odhořívá. Tento typ je velice spolehlivý, protože nemá žádné pohyblivé části. Nemá možnost opakovaného zažehnutí a jeho výkon se dá regulovat jen velmi omezeně, proto se nejvíce používají pro neřízené i řízené střely a pomocné rakety, které např. zkracují vzlet letadel. Tohoto typu jsou i boční stupně amerického raketoplánu.
Motor na kapalné palivo (využívající kapalné pohonné látky tzv. KPL) je výkonnější, účinnější, ale také složitější. Je obvykle napájen ze dvou nádrží. V jedné je palivo a ve druhé okysličovadlo. Palivo je s okysličovadlem do spalovací komory vháněno buď pomocí čerpadel nebo pouze tlakem interního plynu. Čerpadlo může být poháněno například parní turbínou, pro kterou se pára vyrábí rozkladem peroxidem vodíku a manganistanu draselného. U motoru na kapalné palivo je výstupní tryska vysoce tepelně namáhána a proto je vyložena např. grafitem. Komora motoru i tryska bývají také často chlazeny vstupujícím palivem. Tyto motory se používají pro pokusná letadla a veliké rakety o hmotnosti několika tun.
Existují také hybridní raketové motory, které oba principy kombinují. Příkladem může být motor z pokusného letounu SpaceShipOne, který má komoru vyplněnou tuhou hořlavinou a kapalné okysličovadlo je dodáváno z oddělené nádrže.

http://www.auto-motory.com/raketove-motory/
http://cs.wikipedia.org/wiki/Konstantin_Eduardovi%C4%8D_Ciolkovskij

Raketový motor
1.
- tepelný motor
- práce na principu akce a reakce
- nezávislý na atmosférickém kyslíku - možný pohyb mimo atmosféru
- poháněn tuhými a kapalnými palivy
- Při hoření pohonného paliva se uvolňují žhavé plyny, které jsou pak pod silou tlaku vytlačovány do okolního prostoru skrze expanzní tryskou

1,5. Raketa
- čím je raketa lehčí, tím je její rychlost větší.
- nádrž s palivem zabíra 90 % rychlosti rakety, proto byla navržena vícefázová raketa, která může prázdné nádrže vypustit.
- raketovou technikou se zabýval K.E. Ciolkovskij, vytvořil tzv. Ciolkovského rovnici, jejíž pomocí se dá vypočítat, jak se raketa bude pohybovat

1,75.
Konstantin Eduardovič Ciolskovsij
- ruský a sovětský vědec
- zakladatel novodobé kosmonautiky

2. Motor na tuhá paliva
- nemá pohyblivé části (větši spolehlivita)
- není možné opakované zažehnutí, špatná regulace výkonu
- části: Spalovací komora a tryska
- Spalovací komora je téměř celá naplněna palivem a okysličovadlem, které postupně odhořívá
- použití: řízené i neřízené střely a pomocné rakety (zkracují vzlet letadel)


3. Motor na kapalná paliva
- výkonější, účinější a složitějsí než motor na tuhé pohonné látky
- části: spalovací komora, čerpadlo (pokud motor není napájen tlakem interního plynu), výstupní tryska
- palivo a okysličovadlo se vhání do spalovací motory z dvou různých nádrží
- použití: pokusná letadla, veliké rakety o hmotnosti několika tun
 


Imaparfait

25. února 2011 v 11:25 | Marketta |  Le Francais <3

..:imparfait:..

..:minulý čas souminulý:..

tvoření

pravidelná slovesa

tvoří se od přítomného kmene slovesa (trouv|ons, finiss|ons)
je trouvaisnous trouvions
tu trouvaisvous trouviez
il trouvaitils trouvaient
je finissaisnous finissions
tu finissaisvous finissiez
il finissaitils finissaient

nepravidelná slovesa

imparfait nepravidelných sloves se tvoří pravidelně
odlišný kmen má imparfait slovesa être
j'étaisnous étions
tu étaisvous étiez
il étaitils étaient
užívání
1. časově neohraničené trvání minulého děje
2. okolnosti průběhu jiného děje minulého
3. minulý děj opakovaný, znamenající zvyk či návyk
4. časově přesně určenou minulou událost v jejím průběhu
5. zdvořilost
 


Dzoukes

1. února 2010 v 19:34 | Marketta |  Blbinky
A young woman was taking an afternoon nap. After she woke up, she told her husband, "I just dreamed that you gave me a pearl necklace for Valentine's day. What do you think it means?"

"You'll know tonight." he said.

That evening, the man came home with a small package and gave it to his wife. Delighted, she opened it--only to find a book entitled "The meaning of dreams".


flaaaaaaaaags

15. ledna 2010 v 19:42 | Marketta |  Obrázky

EU History - Russia during reign of Nicholas II

11. ledna 2010 v 1:36 | Marketta |  ->SCHOOL<-
Russian Peasantry between 1861 and 1914

Although the Russsian government emancipated Russian peasants not everything seemed to be all right. Petitions and complainments came from all classes of society.
Mostly the petitions were from politians and peasants themselves. Sometimes the petitions came from intelectuals.
The first document shows us that dissatisfaction increased during the reign of tsar Nicholas II. (1894 - 1917).
The politicians and richer people agreed that peasants were uneducated and they didn't know how to handle with the new land that had been given to them. Somewhere even were revolts and rebellions led by peasants.
The reasons why the peasants became dissasfied were many. One of them was issue of that land that had been given to them. The landlords could decide what part of their land they'll give them so the peasants usually got bad soil where the crops didn't have as good quality as they could have had. Another reason of their dissatisfaction were fatal diseases and later famine and they had no protection against them. The peasants also desired for education for themselves and for their children and some of them tried to study at home. In 1906 the peasants made a petition and sent it to Duma. Their main requirements were peace, land and education.

Catherine II. and Elizabeth I.

11. ledna 2010 v 1:11 | Marketta |  ->SCHOOL<-
Catherine II of Russia and Elizabeth I of England

Machiavelli once suggested that a ruler should behave "like a lion" and "like a fox". What I understand by these statements is that a ruler should be hard-working, brave, and royal and do the best for his or her people - just like a lion, the king of all animals. What author means by "be like a fox" is that the ruler has to have something extra, some ace in his sleeve. There could be hundreds of clever and brave rulers but only the one who is enough smart to use some trick will get what he wants.
I picked Catherine the Great of Russia and Elizabeth I of England to describe. I'm going to start with Czarina Catherine:
Catherine was very young when she received a letter from Russian empress inviting her to Russia and lives in there. She came and married her cousin Peter. In 1762 Czarina died and Peter became a tsar. He had planned how to get of Catherine but she was faster and she got rid of him on the coup of 1762. During her reign she made from Russia very successful country.
Czarina showed her "lion" characteristics mainly during and after her marriage with heir of the Russian throne Peter III. She was brave and she fell for Enlightenment opinions. During her marriage she was de facto political prisoner for long eighteen years (until coup of 1762 when she became Russian empress) but she used this time for studying, reading books and writing with the writers of Enlightenment era so she was prepared for role of empress. Another "lion" thing was her hard studying of difficult Russian language.
She worked during her reign for more hours than was usual for any other European ruler. Her first priority was making Russia better country and she worked very hard for it. She made a cruise to make sure the orders she made had been done and she also put into effect a Statute for the Administration of the Provinces of the Russian Empire which divided Russia into provincies and districts which made administration easier.
She also used her "foxy side" for success:
After death of Czarina Elizabeth in 1762 Catherine spent hours with her dead body at church crying and being mourner which made her more popular among her peasants. I really doubt she was really so hearbroken by czarina's death because czarina had imprisoned her and made her life harder (it was pretty much caused by czarina's jealousness to younger and more beutiful Cathrine).
To make sure she won't be deposed from the throne the same way Cathrine deposed her husband she killed another heirs of throne.
Although she had been raised in Lutheran church and she loved her religion after her arrival to Russia she became a member of Russian Orthodox Church and received name of Catherine Alekseyevna.

The queen of England during 16th century Elizabeth I achieved success too. The whole
era is named after her.
She used her "lion side" by supporting English Protestant Church. There were still some Catholics in the country and the previous queen was Catholic, too. Not only that Elizabeth supported this church but she also made herself Supreme Governor allias the head of the church.
The period of her reign was called the Golden Age. England was succesful country and I believe it was because of Elizabeth's not being afraid of changes. She was pretty liberal queen and it made a space for artists like Shakespeare to show their talent.
Interesting is that the "foxy side" is not always good from the moral point od view. Elizabeth imprisoned her relative, Mary, Queen of Scots, for twenty years and then under pressure of her politics let her to be killed.

essay

10. ledna 2010 v 23:01 | Marketta |  ->SCHOOL<-
Contrast of the historical context, beliefs, and behavior of European youth in Germany, year of 1934 and in France, year of 1968.
In 1934 there was Hitler's reign in Germany. Young people joined Hitler Jugend. In 1968 in France there was Student Revolt. The main difference between these two events was that in Germany people were with their government and in France they were against their government.
In 1934 situation in Germany was like this: Hitler's Party won elections and all the German people loved and accepted Hitler. It was the time after the Great Deppresion and people were without job (and therefore without money) and then came Hitler and gave them work at building highways all across the Germany. Therefore not only German people were happier but German country started to look better. Hitler found a Hitler Youth for young people of certain age. The young people were with their leader believing in him and his ideas (or at least accepting them) and this youth represented its country and her ideals.
The situation in France was very different. Young people (students) got dissapointed by government's holding school money. They made a strike and were fighting with government offices for weeks.
The opposite between German young people and French ones was that Germans believed in their leader and French believed in themselves, in their education. The difference in their behavior was that French people were fighting for their ideas and German people shut up and received their leader's ideals.
The photography from Germany represened obedience and the French photography represened revolt.

amendments

7. ledna 2010 v 17:37 | Marketta |  ->SCHOOL<-




14th



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fotec

10. prosince 2009 v 4:34 | Marketta
http://www.facebook.com/photo.php?pid=134385&id=1500237972#/photo.php?pid=371820&id=1500237972&fbid=1145807814285


http://www.facebook.com/photo.php?pid=134385&id=1500237972#/photo.php?pid=142060&id=1500237972&fbid=1053771833443



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