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Monday 22 August 2011

Diesel Cycle - Ideal Cycle for Compression-ignition Engines


Isentropic Compression (1-2)
Click to View Movie (25.0 kB)
The only difference between ideal Otto cycle and ideal Diesel cycle is the heat addition process. Instead of constant volume heat addition process in SI engine, heat is added to the air in the Diesel engine at constant pressure. The four processes are:
  • 1-2 Isentropic compression
  • 2-3 Constant pressure heat addition
  • 3-4 Isentropic expansion
  • 4-1 Constant volume heat rejection

Constant Pressure Heat Addition (2-3)
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Isentropic Expansion (3-4)
Click to View Movie (29 kB)

Constant Volume Heat Rejection (4-1)
Click to View Movie (35 kB)
Noting that the ideal Diesel cycle is executed in a closed system and the working fluid is air according to the air-standard assumption. Also, changes in kinetic and potential energies are negligible. No heat transfer is involved in the two isentropic processes. The energy balances for these two processes are:
      -w12 = u2 - u1
      -w34 = u4 - u3
w12 is negative since work is needed to compress the air in the cylinder and w34 is positive since air does work to the surroundings during its expansion.
In the constant pressure heat addition process, air is expanded to keep the pressure as constant during the heat addition. The expansion work equals
      w23 = P2(v3 - v2)
The energy balances for this process is:
      q23 = u3 - u2 + w23 = h3 - h2
In the constant volume heat rejection process, no work interaction is involved since no volume change occurs. The energy balances for this process is:    
      q41 = u1 - u4
q23 is positive since heat is added to the air and q41 is negative since heat is rejected to the surroundings during this process.
For the whole cycle, the energy balance can be determined by adding the energy balance of its four processes. That is,
      q23 + q41 - w12 - w34 = 0

The thermal efficiency of an ideal Otto cycle is
      ηth,Diesel = wnet/qin
According to the analysis above, the net work output is
      wnet = w34 + w12 = q23 + q41
      qin = q23
      ηth, Diesel = 1+ q41/q23
Under the cold air-standard assumption, the thermal efficiency of an ideal Diesel cycle is
      
In order to simplify the above equation, the cutoff ratio rc is defined as
rc = v3/v2
Process 1-2 and process 3-4 are isentropic. Thus,
      
The thermal efficiency relation reduces to
      

Thermodynamics(Auto cycle, Diesel cycle,Brayton cycle,Gay-Lussac's Law,Efficiency of Heat Engine formulas)


Computer drawing of Otto cycle with p-V plot. Equations to compute
 the engine performance are given
Thermodynamics is a branch of physics which deals with the energy and work of a system. It was born in the 19th century as scientists were first discovering how to build and operate steam engines. Thermodynamics deals only with the large scale response of a system which we can observe and measure in experiments. As aerodynamicists, we are most interested in the thermodynamics of propulsion systems and high speed flows. On this page we consider the thermodynamics of a four-stroke internal combustion engine. Today, most general aviation or private airplanes are powered by internal combustion (IC) engines, much like the engine in your family automobile.
There are two main parts to engine operation: the mechanical operation of the engine parts, and the thermodynamics through which the engine produces work and power. On this page we discuss the basic thermodynamic equations that allow you to design and predict engine performance.
In an internal combustion engine, fuel and air are ignited inside a cylinder. The hot exhaust pushes a piston which is connected to a crankshaft to produce power. The burning of fuel is not a continuous process, but occurs very quickly at regular time intervals. Between ignitions, the engine parts move in a repeated sequence called a cycle. The engine is called a four stroke engine because there are four movements, or strokes, of the piston during one cycle.
On the figure we show a plot of pressure versus gas volume throughout one cycle. We have broken the cycle into six numbered stages based on the mechanical operation of the engine. For the ideal four stroke engine, the intake stroke (1-2) and exhaust stroke (6-1) are done at constant pressure and do not contribute to the generation of power by the engine. During the compression stroke (2-3), work is done on the gas by the piston. If we assume that no heat enters the gas during the compression, we know the relations between the change in volume and the change in pressure and temperature from our solutions of the entropy equation for a gas. We call the ratio of the volume at the beginning of compression to the volume at the end of compression the compression ratio, r. Then
p3 / p2 = r ^ gamma
T3 / T2 = r ^ (gamma - 1)
where p is the pressure, T is the temperature, and gamma is the ratio of specific heats. During the combustion process (3-4), the volume is held constant and heat is released. The change in temperature is given by
T4 = T3 + f * Q /cv
where Q is the heat released per pound of fuel which depends on the fuel,f is the fuel/air ratio for combustion which depends on several factors associated with the design and temperature in the combustion chamber, and cv is the specific heat at constant volume. From the equation of state, we know that:
p4 = p3 * (T4 /T3)
During the power stroke (4-5), work is done by the gas on the piston. The expansion ratio is the reciprocal of the compression ratio and we can use the same relations used during the compression stroke:
p5 / p4 = r ^ (-gamma)
T5 / T4 = r ^ (1 - gamma)
Between stage 5 and stage 6, residual heat is transferred to the surroundings so that the temperature and pressure return to the initial conditions of stage 1 (or 2).
During the cycle, work is done on the gas by the piston between stages 2 and 3. Work is done by the gas on the piston between stages 4 and 5. The difference between the work done by the gas and the work done on the gas is shown in yellow and is the work produced by the cycle. We can calculate the work by determining the area enclosed by the cycle on the p-V diagram. But since the processes 2-3 and 4-5 are curves, this is a difficult calculation. We can also evaluate the work W by the difference of the heat into the gas minus the heat rejected by the gas. Knowing the temperatures, this is an easier calculation.
W = cv * [(T4 - T3) - (T5 - T2)]
The work times the rate of the cycle (cycles per second cps) is equal to the power P produced by the engine.
P = W * cps

On this page we have shown an ideal Otto cycle in which there is no heat entering (or leaving) the gas during the compression and power strokes, no friction losses, and instantaneous burning occurring at constant volume. In reality, the ideal cycle does not occur and there are many losses associated with each process. These losses are normally accounted for by efficiency factors which multiply and modify the ideal result. For a real cycle, the shape of the p-V diagram is similar to the ideal, but the area (work) is always less than the ideal value.

Diesel Cycle

Rudolph Diesel
Rudolph Diesel was born in Paris of Bavarian parents in 1858. As a budding mechanical engineer at the Technical University in Munich, he became fascinated by the 2nd law of thermodynamics and the maximum efficiency of a Carnot process and attempted to improve the existing thermal engines of the day on the basis of purely theoretical considerations. His first prototype engine was built in 1893, a year after he applied for his initial patent, but it wasn't until the third prototype was built in 1897 that theory was put into practice with the first 'Diesel' engine.
Diesel Cycle Operation
The Diesel cycle is the cycle used in the Diesel (compression-ignition) engine. In this cycle the heat is transferred to the working fluid at constant pressure. The process corresponds to the injection and burning of the fuel in the actual engine. The cycle in an internal combustion engine consists of induction, compression, power and exhaust strokes.
Induction Stroke
The induction stroke in a Diesel engine is used to draw in a new volume of charge air into the cylinder. As the power generated in an engine is dependent on the quantity of fuel burnt during combustion and that in turn is determined by the volume of air (oxygen) present, most diesel engines use turbochargers to force air into the cylinder during the induction stroke.
From a theoretical perspective, each of the strokes in the cycle complete at Top Dead Centre (TDC) or Bottom Dead Centre (BDC), but in practicality, in order to overcome mechanical valve delays and the inertia of the new charge air, and to take advantage of the momentum of the exhaust gases, each of the strokes invariably begin and end outside the 0, 180, 360, 540 and 720 (0) degree crank positions (see valve timing chart).
 
Compression Stroke
The compression stroke begins as the inlet valve closes and the piston is driven upwards in the cylinder bore by the momentum of the crankshaft and flywheel.
The purpose of the compression stroke in a Diesel engine is to raise the temperature of the charge air to the point where fuel injected into the cylinder spontaneously ignites. In this cycle, the separation of fuel from the charge air eliminates problems with auto-ignition and therefore allows Diesel engines to operate at much higher compression ratios than those currently in production with the Otto Cycle.
Compression Ignition
Compression ignition takes place when the fuel from the high pressure fuel injector spontaneously ignites in the cylinder.
In the theoretical cycle, fuel is injected at TDC, but as there is a finite time for the fuel to ignite (ignition lag) in practical engines, fuel is injected into the cylinder before the piston reaches TDC to ensure that maximum power can be achieved. This is synonymous with automatic spark ignition advance used in Otto cycle engines.
 
Power Stroke
The power stroke begins as the injected fuel spontaneously ignites with the air in the cylinder. As the rapidly burning mixture attempts to expand within the cylinder walls, it generates a high pressure which forces the piston down the cylinder bore. The linear motion of the piston is converted into rotary motion through the crankshaft. The rotational energy is imparted as momentum to the flywheel which not only provides power for the end use, but also overcomes the work of compression and mechanical losses incurred in the cycle (valve opening and closing, alternator, fuel injector pump, water pump, etc.).
Exhaust Stroke
The exhaust stroke is as critical to the smooth and efficient operation of the engine as that of induction. As the name suggests, it's the stroke during which the gases formed during combustion are ejected from the cylinder. This needs to be as complete a process as possible, as any remaining gases displace an equivalent volume of the new charge air and leads to a reduction in the maximum possible power.
 
Exhaust and Inlet Valve Overlap
Exhaust and inlet valve overlap is the transition between the exhaust and inlet strokes and is a practical necessity for the efficient running of any internal combustion engine. Given the constraints imposed by the operation of mechanical valves and the inertia of the air in the inlet manifold, it is necessary to begin opening the inlet valve before the piston reaches Top Dead Centre (TDC) on the exhaust stroke. Likewise, in order to effectively remove all of the combustion gases, the exhaust valve remains open until after TDC. Thus, there is a point in each full cycle when both exhaust and inlet valves are open. The number of degrees over which this occurs and the proportional split across TDC is very much dependent on the engine design and the speed at which it operates.

Monday 8 August 2011

Mayan Civilization and Pyramids


Allowing us to trace the Mayan Civilization back in history as far as 3, 000 years, tells us that we have much to learn of the Mayan People. The people came from the southern part of mexico and the northern part of central America. Archaeological evidence shows us hat they began building their charactristic ceremonial structures (Mayan Pyramids) or Pyramid Temples, right back 3, 000 years ago. They belong from the Terminal pre-classic period and can be traced from before this time in some cases, they first seen as burial mounds.

There are two types of Mayan Pyramids: A climbing pyramid and the other was built for non climbing purposes, infact the purpose was thought to be that to be used to carry out sacrificial rituals. The climbing Pyramid strangley was not built for climbing at all, it had very steep steps leading to doorways that infact lead literally to nowhere!

Some of the pyramids consisted of as many as four staircases one for each side, others had a mere two on each side. The point was that when the priests or kings performed their rituals, they ascended the Pyramid from the staircases, which was a symbol of rising from earth to heaven. Obviously they would start from the ground and make their way up to the temple top, on the top was a constructed smaller building. Also situated somewhere in the middle was a platform that would connect the staircases, the priest or king would rest there and perform part of the ritual before continuing to the peak of the Pyramid.

Pyramids built as burial places were not just built for kings and priets but were also built specially for those with higher power. There were a certain Mayan Pyramid like construction. Normally these burial chambers contained treasures such as Jade.

These Pyramid like constructions could been seen above the tops of the jungle, they served as landmarks for the Mayan Civilization. It was also a reminder to the people that the Ancient Gods were also present!

The Pyramids also held symbolization for mountains, like thier temples held symbolization for something very different, according to historians the temples were a symbol to the caves that led to the underworld, while the doorways were representative of the mouths of monsters, and hence were embellished accordingly. The Mayan people had a great reputation of being keen astronomers, therefore using their pyramid structures as observatories. As well as religion, period of time and customs to each region, it was said that the pyramids were built accordingly serving the variety of functions and purposes.

There was no aids of help taken when building these hugh structures, not domestically anyway, no animals or wheels which had not been invented then. It was also not common to use metal tools, thi swas because it was common in the region of which they inhibited.

The tools they made use of were made of quartize, granite, limestone, and flint on stone, tools used for example were fire axes and basalt axes. To correctly judge the vertical accuracy tools like plumb bob were used.

Given below are some of the great townships that were built during the 1, 500 years that the Mayans had flourished in the expanses of the Yucatan Peninsula of Mexico, and in the verdant jungles of Honduras, Belize, and Guatemala, in which they built their distinctive pyramids, like Chichen Itza, Tulum, Uxmal, Tikal, Cholula, Copan, and Calacmul.

Its massive pyramids, including the enormous El Castillo pyramid which contains a jaguar throne, have wonderful murals and carvings. Dedeicated to the rain God, a natural well is found, it was used for making human sacrifices!

Tikal: Covering 60 squares miles and located in Guatemala lays the laregst city of the Mayan people. The Temple Pyramid, being the largest out of many of the Mayan Pyramids, boasts 230 feet in height. It was said for these pyramids to have been built from the period of the 7th century and headin out of the early part of the 9th century.

Uxmal: This was regarded as the most beautiful of the Mayan populated cities, given again its location in Mexico. It has the 'Pyramid of Magician'. Ithas been given its distinctive individuality as it is the only one with an oval base, instead of the usual square or rectangular shape. It provides us with fantsic breath taking views from the Pyramis terraces, also genrously offering us wonderful acoustics. The other numerous, temple Pyramids, monuments and quadrangles are given some considerable size, and are in various degrees of preservation.

Cholula: This Pyramid without doubt has earnt its right to be given the name 'the great pyramid of cholula'. It was conisdered to be the largest of them all including the Great Pyramid of Egypt, making it really the largest in the world. Later, however, another pyramid found in the ruins of El Mirador, in Guatemala, known as the Danta Pyramid has overtaken it by size, measuring up to 230 feet in height. However the main Pyramid of Cholula is very big, given a base covering 25 acres of land! As now it has the look of of being a natural hill with a church on its peak, Mayan Pyramids are similarly covered by earth and are given a catholic church to surmount on them.

Calakmul: Also known as Kalakmul, this is one of the largest amongst the ancient Mayan cities that have been discovered. It is situated in the Calakmul Biosphere Reserve, 30 km from the border of Guatemala, in the Petén jungles. The name of this city means ‘City of the Two Adjacent Pyramids.’

During their astonishing time of inhibitation, they built many more Mayan Pyramids of various sizes and fame in all their ancient cities. The presence of these wonderful structures reminds us chilingly of their former presence and disappearence of their own civilization. It was said to have been in the 10th century period when the civilization left the mysteries of themselves to the world history. Rightly earned recently these fabulous Pyramids have yet again stolen the attentions of the world and have been given the name as one of the most new seven wonders of the world!

Ten scenarios for the end of the world

All mankind shivers in anticipation of December 2012, when according to some interpreters of the Mayan calendar the end of the world will come.

Will the end of humanity really come? The British newspaper "Daily Telegraph" published the 10 most-circulated in recent years, scenarios for the end of the Earth.

Invasion of aliens

This version was more popular than back in 1898 when HG Wells published his novel "War of the Worlds". But scientists have found an interesting trend - fears of a deadly alien attack are increased at a time when people are afraid of more worldly threats.

- At the beginning of the 21st century an unknown planet will interject with the Earth, and will destroy civilization, or will cause a huge natural disaster. This scenario is based on fiction invented by the American Zekariya planet Nibiru Sitchin.

Every 3700 years Nibiru ends up in the inner part of our planetary system, but there are Mercury, Venus, Earth and Mars. Proof of the existence of Nibiru exists. In 2005, NASA announced that it has finally found a planet of our solar system and many believe that it will pass in 2012 near the Earth and will somewhat affect us.

- A powerful solar flare will swallow the Earth. Scientists actually believe that when the sun "exhausted its fuel, " it will swell to the size of a red giant, will explode and then swallow the Earth. That will happen no sooner than 5 billion years.

- Theory of the Earth's shifting magnetic poles. According to its supporters this will cause a change in the rotation of the planet and subsequent catastrophic events.

Scientists from Princeton University and the University "Paul Sabatier" in Toulouse found that Earth did some "re- balancing", 800 million years ago. They studied the minerals in rocks sediments in Norway and found that the north pole has shifted by 50 degrees in 20 million years. Such a shift will be due again in the very near future, predict the supporters of apocalyptic theories. According to geologists, however, this will happen over a period of 1 million years.

- The outbreak of a super volcano. Such volcanic explosion would occur when magma rose in the bowels of the earth, but can not find its way out, researchers explain. Enormous pressure accumulates, which ultimately will lead to a giant explosion. Such a cataclysm would spew into the air tons of toxic gases and volcanic debris, and would cause a new ice age and would destroy the life of the planet.
Ten scenarios for the end of the world

A similar explosion may be in a giant caldera in Yellowstone National Park in the U.S.. Satellite images in recent years there have shown changes in the movement of molten rock at a depth of 16 kilometers. But now, nobody knows if and when this caldera will erupt.

- World War III, for which will be used nuclear weapons. This scenario was updated during the Cold War. After the collapse of the Soviet Union, Cold War fears allayed. In recent years, concern has also been returned because of Iran's nuclear program, tensions on the Korean Peninsula and continuing tensions between India and Pakistan - two countries with nuclear arsenals.

Last year in Prague, Barack Obama tried to dispel these fears with the promise of a world free of nuclear weapons.

- The act of terrorism with weapons of mass destruction. After the attacks on the twin towers in New York on September 11, 2001, when nearly 3, 000 people died, fears of scenario # 7 have risen sharply. Western governments are talking about the danger of similar attacks against major cities.

At the opposite end is the conspiracy theory that the September 11 attacks were planned and carried out by the U.S. administration. Currently there is no evidence that Al Qaeda has nuclear weapons.

- Peak demand for oil will lead to the end of the world. Demand will be much greater than supply and shortage of oil supplies will have huge implications worldwide. Most economies are powered by oil, agriculture depends on it, the plastics industry is based entirely on it. Such a crisis would lead to collapse of social order.

According to optimists, this will occur by 2020, some oil giants, however, acknowledged that they have overestimated their oil reserves and raised fears that we have entered an era when demand for oil is greater than supply.

- Scenario number 9 is associated with the phenomenon observed in the winter of 2008 - the extinction of whole colonies. And over a third of commercial bee swarms in the U.S. died as a result of the collapse of the syndrome of bee colonies.

Syndrome spread to several European countries including France, Belgium, Italy, Spain and Portugal. Several reasons were identified for the disease - pesticides, Israeli acute paralysis virus, wax moths, climate change, mobile phones and their networks.

New cases of the disease were previously reported by affected parties and hanging the threat of a pandemic on the bees, which can lead to their complete disappearance. If something like this happens, several cultures that are important to people, would disappear. These include soybeans, cotton, some nuts, grapes, apples, sunflowers, etc.

Third of the food consumed in the world is produced due to unsuspected involvement of bees. So the extinction of bees could lead to shortages of some foods, which leads to migration, violence, wars.

- Global warming and climate change. This can lead to multiplication of elements, from floods, to droughts ... Few scientists dispute the fact that average global temperatures increased last century. There were, however, climate skeptics, who discovered the errors and poorly substantiated conclusions in reports of international organizations for change, said that climate change data are manipulated by climatologists.

The world today has taken to counteract this phenomenon, and organized several international conferences on climate change.

Mysterious Nazca lines

Centuries ago, deserts, hills and mountains in the Pacific coast of South America were covered by an extensive network of drawings, lines and geometric shapes, figures of mammals, insects and deities. Nazca lines opened in 1927, and are a most extraordinary legacy left by the culture that flourished 2, 000 years ago. These lines and other figures represent a series of complex projects, some of them with long miles, which can be seen in their true dimension only from heaven. Not to be assumed that then the Nazca culture were able to fly, but still remains the question of how these drawings are made, what technologies are used and for what purpose have these lines been made?
Nazca Lines

City Nazca was founded in 1591 by the Spanish who conquered Nazca on plateau without any knowledge of what is located nearby. Today Nazca is a small, underdeveloped town, the main economic activity is based on tourism associated with unusual shapes, agriculture and trade. Tourism is directly related to the Nazca lines and other archaeological complexes such as the Kahuachi, Estakueriya, Chauchila tombs and the lines of Palpa valley.

Who drew the lines of Nazca?

Undoubtedly, after this question comes a number of questions, namely: Ancient religion? Did aliens came from space? Ancient astronomers? Artists with extraordinary opportunities? Initially it was thought that these pieces are the remains of irrigation canals in the flooded valley of Nazca. But after having been seen from the air, it became clear that the lines are fully recognizable as a huge network of amazing artifacts as they are in reality.

There are many hypotheses about the emergence of these incredible pieces, such as Erich von Danica, who claims to the 'chariots of the gods' that they are remnants of a giant extraterritorial airport. But the reality is often much more mysterious than fiction and this is exactly the case with Nazca and other artifacts of ancient cultures of Peru. Long before Inca they managed four kingdoms Nazca, Parakas, Kazma and Karan and yet with no plants were still able to calculate the passing time and seasons, and have built some of the oldest cities in the world.

New Science of Nazca lines

With the advancement of science we are able to learn more about ancient civilizations that may have created the Nazca lines and other mysterious figures.

In August 2007 a new science is presented by Anthony Pera, John McGovern, Alfred Koyayama, Marinus Anthony van der Slazhs and Matthias Wash. This new theory of science explores the relationship between prehistoric stone carvings, shapes of the earth and the periodic and extraordinary intensity of emission and appearance of the glow. There is a very high energy radiance if the world finishes and starts again repeating itself every several thousand years. This not only provokes high energy radiance but also provokes the changing of colors and patterns.

In many cases this can also reproduce static high energy radiation on the ground, resulting in the formation of a 'glass like wildfire' which also forms patterns that differ substantially from the ordinary to lightening strikes, namely in the form of lines, as are the Nazca lines.

Make-up of ancient Egyptians protected against infections

Thick painted eyes of the ancient Egyptians were not only beauty but also a healthy goal. Namely, to protect them from infection. Assumption groups voiced by French scientists to the "National Geographic".

Ancient Egyptians believed that make-up ocular had magical properties, drawing eyes so they can provide protection from the gods Ra and Horus against diseases such as eye infections such as conjunctivitis, which are commonly found in marshy areas near the Nile.

Generally found in the make-up of the Egyptians are four components, based on the lead. It was therefore considered that the make-up of Cleopatra and her subordinate was harmful.
Make-up of ancient Egyptians protected against infections

The new study, however, is not so. The make-up contained low doses of lead salts. They have positive qualities, as in contact with skin they stimulate the production of nitric oxide. This is a chemical that stimulates the immune system and helps in the battle against bacteria.

"Two of the components contained in the make-up of the Egyptians, are not found in their natural state and has required 30 day to be created. In my opinion, the Egyptians knew that these ingredients improve Health and produced them intentionally, " reported one participant in the study, from the University Pierre et Marie Curie in Paris.

Ancient Egyptians and kissing death

Grave of men kissing was discovered in 1964 during an archaeological excavation of ancient tombs in the vicinity of Cairo. Once the archaeologists dug the tomb, they found neither the king nor treasures.

It shocked them somewhat, but the surprise came later. On the wall of the tomb were buried embossed images. These were two men. Surprisingly, however, was that they were frozen in a hug.

Their hands were intertwined, and their noses rub each other, which in ancient Egypt are believed to be an intimate kiss. A relief was written under their names and these were Nianhhnum and Hnumhotep. Egyptologists decipher them and give their occupation; they were personal manicurists to the Pharaoh during the fifth dynasty.

In the tombs of the Pharaoh were found his wife, children and even pets but never the latter husband who does not seem to be of a direct relative. Scientists still disagree on the question of relations between the two manicurists.

According to one hypothesis they were Siamese twins who just cannot but touch each other. According to others their relationship was pure love and therefore those who buried them have enabled them to be together in death.

Scientists have not yet discovered the mysterious reasons for this strange burial. They believe that the truth on this issue will shed light on homosexual relationships in the palace of the ancient Pharaohs.

Volcano struck the Neanderthals

Scientists from Russia announced in the newspaper, that it was 40, 000 years ago that the powerful volcano struck Neanderthals in Europe.

The eruption caused a "volcanic winter", which has proved fatal for the Neanderthals.
Volcanic Eruption

Modern humans have survived because at that time they lived in Africa and Southwest Asia, away from the reach of volcanic ash clouds.

Neanderthal is an extinct man that lived in Europe and western Asia in the era of the middle Paleolithic (130, 000 to 14, 000 BC). Until recently, Neanderthals have been regarded as subspecies of Homo sapiens and have been classified under the name, Homo sapiens neanderthalensis.

According to modern scientists, Neanderthals are materially different from modern man, with whom he has developed in parallel as a separate species. The two types of people likely shared a common ancestor, but Neanderthal does not fit into any evolutionary theory as a direct ancestor of modern man.

Researchers found deposits of volcanic dust in the cave in the Caucasus, which showed that Neanderthals were overtaken by an ecological disaster.

Among the deposits were very small plants. The disappearance of plants has been disastrous for the large mammals as they were the main food for the Neanderthals.

The scientist's team analyzed layers in the cave and discovered two types of volcanic ash which corresponded to two separate eruptions 45, 000 and 40, 000 years ago.

The first of the two eruptions was in the territory of the Caucasus and was weaker. The second, however, was very strong and was in what is now southern Italy.

Parts of the book of the dead were found in the sarcophagi

During excavations in El-Fayum oasis located 100 kilometers from Cairo 57 tombs have been discovered. Many of them have remained in very good condition and include a painted wooden sarcophagi.

They are of the eighteenth dynasty that ruled Egypt and the oldest of these tombs is 2750 BC. In this oasis, archaeologists have found items that may shed new light on the beliefs of the ancient Egyptians.

One of the oldest tombs proved to be virtually untouched by thieves. Mummies in all newly discovered tombs are covered with canvas.

The tomb was decorated with religious texts of the famous "Book of the Dead" and the scenes featuring ancient Egyptian deities, whose purpose was to help the deceased to undergo such tests of the afterlife.

One of the best preserved texts of the Book of the Dead refers precisely to the time of the eighteenth dynasty, when this work had intervened in a new stage of development.

Then the texts were moved on to the papyrus sarcophagi. Most of the papyrus texts from the mysterious book have been discovered in the tombs at Thebes. This caused the Book of the Dead to be called The Book of Thebes.

The papyrus was richly decorated with fine paintings that depicted scenes and burial containers in the afterlife. Researchers shared a special interest in the 125th page of the book, which describes the court of Osiris, who judged the deceased.

Osiris was the king and judge in the world of the dead, he was seated on a throne with the signs of kingship - crown, scepter and scourge. Above him is depicted, the god 42.

These are probably the gods of the different Egyptian regions. In the center of the room stood a statue of God Gore and God Anubis, it was a symbol of the soul of the ancient Egyptians.

In one part of the statue is the heart, mild or burdened with sins is the other - a reality in the form of the goddess Mahath. If a person has led a righteous life, his heart was with the severity of the statuette.

If he was wrong, the heart was more severe. Excuses from the deceased would go to paradise after death, but the sinner is eaten by the monster Amato, which constitutes a lion with a crocodile head.

Book of the Dead is a religious collection in which moral certainties are intertwined with ancient magic. In this collection there are prayers, songs and spells associated with the cult of the afterlife.

This colorful mix is explained by the fact that probably the Book of the Dead was edited and enriched for several centuries. Ancient texts have traditionally remained until recent times, although their content is to remain uncertain for the new generations.

Mayan calendar does not predict the end of the world

Mayan CivilizationScientists from around the world continue to study the Mayan calendar, according to which during the time and year of 21/12/2012 the world will come to an end on planet earth.
In the calendar it is described that on December 21st the sun will rise to the center of the Milky Way, listed as a black hole. Over the past five years, astronomers have discovered that in fact there is a huge black hole at the center of our Milky Way galaxy.
Modern astronomers supported the hypothesis that on the 21st December 2012 the situation on the ground will be aligned with the sun and the center of our Milky Way galaxy. This event happens once every 25, 800 years. Nobody knows what will be the effect, but the Mayans believed that something terrible would happen.
But does this have grounds for concern?
While studying the calendar of the extinct civilization, Michael Coe of Harvard University in 1966 concluded that after the calendar ends on December 21st 2012, then on that day so will come the end of the world.
However, many modern scholars have strongly opposed the theory that the planet will be deleted. Maya is one of the smartest and progressive civilizations born on Earth so far.
In their philosophy, time has never existed as a concept to the end of the world. Mayan Time is cyclical, it has no beginning and no end.
According to Mayan humanity we will be reborn again, but on another planet!

Volcanoes hide anciant Myan secrets

Volcanic ash is falling systematically on the land of Mayan mystery explains how ancient metropolises have prospered in relatively poor soil, through which they survived.

Metropolitan areas of the Maya were built relatively far from the volcanoes in their land, but a new study shed light on how these Cities have survived, says "National Geographic".
Mayan Ruins

Mayan empire stretched from today’s southern Mexico through Guatemala to northern Honduras and flourished between 250 and 900 year BC and then declined.

Recently scientists discovered beige clay minerals in the ducts of the archaeological site Tikal in Guatemala, where in the past was the largest city in the southern lands of the Maya.

This mineral, which is volcanic can be formed only after the fall of volcanic ash. Scientists made this chemical analysis to establish the source and found that the material of Tikal comes from volcanoes on the territory of modern states Salvador, Guatemala, Honduras and Mexico.

"Minerals are talking about a series of volcanic events in the past, " says team leader Ken Tankarsli, an anthropologist at the University of Cincinnati.

Chalchuapa Mayan city in El Salvador was burned to the ground in a volcanic eruption in the sixth century. Scientists link the currents and dust to many distant cities of the Maya.
Mayan Pyramids

Samples of volcanic dust in Tikal are formed over a long period - from 340 BC to 990 BC by.

"There is no way to determine the number of eruptions, their frequency, or what kind of volcanic dust comes, " said Tankarsli.

The new discovery is considered very important because it explains the mystery of the Mayan lowland cities. Surrounding soil was very fertile. It was composed mainly of limestone and was not suitable for feeding many people. Yet in these places have lived between 160 and 230 people per square mile. The numbers puzzled scientists.

If the lowland of Maya cities, the fields were covered with volcanic ash for several years or even decades, soil there has been periodically enriched.

Then the powder was to improve soil fertility, and has increased its water permeability and porosity, and thus improves the ability to retain water. Volcanic ash is a source of useful items such as plants iron and magnesium.

Even a thin layer of volcanic ash, of several centimeters, may increase fertility for long. Moreover, some of it chokes harmful insects.

The Mayans believed that they could delay or prevent the eruption, having performed blood rituals and fed the spirits and gods to monitor volcanoes.

"They have built temples in the form of volcanoes and rituals were, like volcanic events. Volcanoes have been an integral part of Mayan life, " said Tankarsli.

Secrets of the Cheops pyramid

"Everything fears time, time fears the pyramids." This thought strikes each stood before the grandeur of the Egyptian pyramids. The most amazing buildings in human history were built approximately around 4600 years ago. Among them stands one of the last survivors to this day wonders of the world, the Great Pyramid.
According to Egyptian mythology, in this magnificent building should be preserved for eternity the mummy and treasures of the then ruler - Cheops. Some modern scholars believe that building there was for quite a different purpose than the common version. Others even believe that this was a giant machine for the production of excess energy.
One of today's consistently tantalizing questions: How can people who have had only stone hammers and copper chisels build such a huge building? According to ancient legends, Egyptian people inherited their incredible knowledge in ancient civilization. Unfortunately, very few reports have reached us, of how the pharaoh built the largest pyramid in the world. According to information disseminated, Egyptian priests told Herodotus that Cheops was a cruel tyrant. When he took the Egyptian throne, he brought misery to the country and forced everyone to work for him.
Another prominent historian named Diodorus does tell us that people hated the ruler so that they threw him in the mummy's tomb. Indeed, when the first treasure hunters penetrated into his tomb the sarcophagus was found there empty. There is another unsolved riddle on the construction of the ancient giant. If it was just the tomb, why was necessary the incredible mathematical perfection of both project?
According to modern theories, the pyramid is a scale model of the globe. Parallel and meridian, which intersect with it go through most of Earth. Therefore, it appears that it is located in the center of the Earth. While there is still much work needed, data archeology, mathematics and other sciences lead to the conclusion that the Great Pyramid is an impressive facility for capturing a mysterious energy field.
According to another theory, the pyramids at Giza are arranged like the stars in the constellation Orion. Researchers have many theories on the construction of the world of the ancient giants of the desert, but no exact answer to this day. These magnificent facilities survived millennia, and remain vigilant to keep their secrets. And we still only hope that soon a great mind will be able to unveil the mystery of the greatest surviving wonder of the world - the Great Pyramid.