ALBERT EINSTEIN

ALBERT EINSTEIN
THE GREAT PHYSICIST

MY PHYSICS WORLD

EVERYTHING IS ALL ABOUT PHYSICS. THINK PHYSICS, THINK POSSIBILITY!

Sunday, May 29, 2011

SOLAR PANEL



A solar panel (photovoltaic module or photovoltaic panel) is a packaged interconnected assembly of solar cells, also known as photovoltaic cells. The solar panel can be used as a component of a larger photovoltaic system to generate and supply electricity in commercial and residential applications.
Because a single solar panel can only produce a limited amount of power, many installations contain several panels. A photovoltaic system typically includes an array of solar panels, an inverter, may contain a battery and interconnection wiring.

Theory and construction
Solar panels use light energy (photons) from the sun to generate electricity through the photovoltaic effect. The structural (load carrying) member of a module can either be the top layer or the back layer. The majority of modules use wafer-based crystalline silicon cells or thin-film cells based on cadmium telluride or silicon. The conducting wires that take the current off the panels may contain silver, copper or other conductive (but generally not magnetic) transition metals.
The cells must be connected electrically to one another and to the rest of the system. Cells must also be protected from mechanical damage and moisture. Most solar panels are rigid, but semi-flexible ones are available, based on thin-film cells.
Electrical connections are made in series to achieve a desired output voltage and/or in parallel to provide a desired current capability.
Separate diodes may be needed to avoid reverse currents, in case of partial or total shading, and at night. The p-n junctions of mono-crystalline silicon cells may have adequate reverse current characteristics that these are not necessary. Reverse currents waste power and can also lead to overheating of shaded cells. Solar cells become less efficient at higher temperatures and installers try to provide good ventilation behind solar panels.
Some recent solar panel designs include concentrators in which light is focused by lenses or mirrors onto an array of smaller cells. This enables the use of cells with a high cost per unit area (such as gallium arsenide) in a cost-effective way.
Depending on construction, photovoltaic panels can produce electricity from a range of frequencies of light, but usually cannot cover the entire solar range (specifically, ultraviolet, infrared and low or diffused light). Hence much of the incident sunlight energy is wasted by solar panels, and they can give far higher efficiencies if illuminated with monochromatic light. Therefore another design concept is to split the light into different wavelength ranges and direct the beams onto different cells tuned to those ranges. This has been projected to be capable of raising efficiency by 50%. The use of infrared photovoltaic cells has also been proposed to increase efficiencies, and perhaps produce power at night.
Sunlight conversion rates (solar panel efficiencies) can vary from 5-18% in commercial products, typically lower than the efficiencies of their cells in isolation. Panels with conversion rates around 18% are in development incorporating innovations such as power generation on the front and back sides.[citation needed] The Energy Density of a solar panel is the efficiency described in terms of peak power output per unit of surface area, commonly expressed in units of Watts per square foot (W/ft2). The most efficient mass-produced solar panels have energy density values of greater than 13 W/ft2.

Crystalline silicon modules
Most solar modules are currently produced from silicon PV cells. These are typically categorized into either monocrystalline or multicrystalline modules.

Thin-film modules
Third generation solar cells are advanced thin-film cells. They produce high-efficiency conversion at low cost.

Rigid thin-film modules
In rigid thin film modules, the cell and the module are manufactured in the same production line.
The cell is created on a glass substrate or superstrate, and the electrical connections are created in situ, a so called "monolithic integration". The substrate or superstrate is laminated with an encapsulant to a front or back sheet, usually another sheet of glass.
The main cell technologies in this category are CdTe, or a-Si, or a-Si+uc-Si tandem, or CIGS (or variant). Amorphous silicon has a sunlight conversion rate of 6-12%.

Flexible thin-film modules

Flexible thin film cells and modules are created on the same production line by depositing the photoactive layer and other necessary layers on a flexible substrate.
If the substrate is an insulator (e.g. polyester or polyimide film) then monolithic integration can be used.
If it is a conductor then another technique for electrical connection must be used.
The cells are assembled into modules by laminating them to a transparent colourless fluoropolymer on the front side (typically ETFE or FEP) and a polymer suitable for bonding to the final substrate on the other side. The only commercially available (in MW quantities) flexible module uses amorphous silicon triple junction (from Unisolar).
So-called inverted metamorphic (IMM) multijunction solar cells made on compound-semiconductor technology are just becoming commercialized in July 2008. The University of Michigan's solar car that won the North American Solar challenge in July 2008 used IMM thin-film flexible solar cells.
The requirements for residential and commercial are different in that the residential needs are simple and can be packaged so that as technology at the solar cell progress, the other base line equipment such as the battery, inverter and voltage sensing transfer switch still need to be compacted and unitized for residential use. Commercial use, depending on the size of the service will be limited in the photovoltaic cell arena, and more complex parabolic reflectors and solar concentrators are becoming the dominant technology.
The global flexible and thin-film photovoltaic (PV) market, despite caution in the overall PV industry, is expected to experience a CAGR of over 35% to 2019, surpassing 32 GW according to a major new study by IntertechPira.

Module embedded electronics
Several companies have begun embedding electronics into PV modules. This enables performing Maximum Power Point Tracking (MPPT) for each module individually, and the measurement of performance data for monitoring and fault detection at module level. Some of these solutions make use of Power Optimizers, a DC to DC converter technology developed to maximize the power harvest from solar photovoltaic systems.

Module performance and lifetime
Module performance is generally rated under Standard Test Conditions (STC) : irradiance of 1,000 W/m², solar spectrum of AM 1.5 and module temperature at 25°C.
Electrical characteristics include nominal power (PMAX, measured in W), open circuit voltage (VOC), short circuit current (ISC, measured in amperes), maximum power voltage (VMPP), maximum power current (IMPP), peak power, kWp, and module efficiency (%).
Nominal voltage refers to the voltage of the battery that the module is best suited to charge; this is a leftover term from the days when solar panels were used only to charge batteries. The actual voltage output of the panel changes as lighting, temperature and load conditions change, so there is never one specific voltage at which the panel operates. Nominal voltage allows users, at a glance, to make sure the panel is compatible with a given system.
Open circuit voltage or VOC is the maximum voltage that the panel can produce when not connected to an electrical circuit or system. VOC can be measured with a meter directly on an illuminated panel's terminals or on its disconnected cable.
The peak power rating, kWp, is the maximum output according to STC (not the maximum possible output).

Solar panels must withstand heat, cold, rain and hail for many years. Many crystalline silicon module manufacturers offer a warranty that guarantees electrical production for 10 years at 90% of rated power output and 25 years at 80%.

Production
15.9 GW of solar PV system installations were completed in 2010. Solar PV pricing survey and market research company, PVinsights reported a 117.8% growth of solar PV installation on a year-on-year basis.With over 100% year-on-year growth in PV system installation, PV module makers dramatically rose up their shipments of solar panel in 2010. They actively expanded their capacity and turned themselves into Giga-watt GW Player. According to PVinsights, five of top 10 PV module companies in 2010 are GW player. Suntech, First Solar, Sharp, Yingli, Trina Solar are GW players now and most of them doubled their shipments in 2010.

Top ten
Top ten solar panel producers(by MW shipments) in 2010 were:
1. Suntech
2. First Solar
3. Sharp Solar
4. Yingli
5. Trina Solar
6. Canadian Solar
7. Hanwha Solarone
8. Sunpower
9. Renewable Energy Corporation
10. Solarworld

Price
Average pricing information divides in three pricing categories: those buying small quantities (modules of all sizes in the kilowatt range annually), mid-range buyers (typically up to 10 MWp annually), and large quantity buyers (self explanatory—and with access to the lowest prices). Over the long term—and only in the long-term—there is clearly a systematic reduction in the price of cells and modules. For example in 1998 it was estimated that the quantity cost per watt was about $4.50, which was 33 times lower than the cost in 1970 of $150.
Following to RMI, Balance-of-System (BoS) elements, this is, non-module cost of non-microinverter solar panels (as wiring, converters, racking systems and various components) make up about half of the total costs of installations. Also, standardizing technologies could encourage greater adoption of solar panels and, in turn, economies of scale.

Mounting Systems
Trackers

Solar Trackers increase the amount of energy produced per panel at a cost of mechanical complexity and need for maintenance.

Fixed Racks

Fixed racks hold panels in a single location as the sun moves across the sky.
The fixed rack sets the angle at which the panel is held. Tilt angles equivalent to an installation's latitude is common.

Standards
Standards generally used in photovoltaic panels:
* IEC 61215 (crystalline silicon performance), 61646 (thin film performance) and 61730 (all modules, safety)
* ISO 9488 Solar energy—Vocabulary.
* UL 1703
* CE mark
* Electrical Safety Tester (EST) Series (EST-460, EST-22V, EST-22H, EST-110).

Devices with photovoltaic modules
Further information: Solar panels on spacecraft and Solar charger
Electric devices that includes solar panels:
* Solar cell phone : Sharp announced that its first solar-powered cell phone would be released in summer, 2009.
* Solar lamp
* Solar notebook: IUNIKA makes the first Solar Powered Netbook, the Gyy.[10]
* Solar-pumped laser
* Solar vehicle
* Solar plane
Space stations and various spacecraft employ, or have employed photovoltaic panels to generate power.
* Soyuz spacecraft
* International Space Station
* Skylab space laboratory
* Mir space station

A PV MODULE ON ISS

Thursday, May 26, 2011

BIOGRAPHY OF ALBERT EINSTEIN



Albert Einstein (March 14, 1879 – April 18, 1955) was a German-born American theoretical physicist who is widely regarded as the greatest scientist of the 20th century. He proposed the theory of relativity and also made major contributions to the development of quantum mechanics, statistical mechanics, and cosmology. He was awarded the 1921 Nobel Prize for Physics for his explanation of the photoelectric effect and "for his services to Theoretical Physics".


The parents of Albert Einstein, Pauline Koch and Hermann Einstein

After his general theory of relativity was formulated in November 1915, Einstein became world famous, an unusual achievement for a scientist. In his later years, his fame exceeded that of any other scientist in history, and in popular culture, Einstein has become a byword for great intelligence or even genius.

Einstein himself was deeply concerned with the social impact of scientific discovery. An individual of monumental intellectual achievement, he remains the most influential theoretical physicist of the modern era. Einstein's reverence for all creation, his belief in the grandeur, beauty, and sublimity of the universe (the primary source of inspiration in science), his awe for the scheme that is manifested in the material universe—all of these show through in his work and philosophy. To this day Einstein receives popular recognition unprecedented for a scientist.

Biography

Youth and college



First Photo of Albert Einstein


Young Einstein before the Einsteins moved from Germany to Italy.

Einstein was born at Ulm in Baden-Württemberg, Germany, about 100 km east of Stuttgart. His parents were Hermann Einstein, a featherbed salesman who later ran an electrochemical works, and Pauline, whose maiden name was Koch. They were married in Stuttgart-Bad Cannstatt. The family was Jewish (and non-observant); Albert attended a Catholic elementary school and, at the insistence of his mother, was given violin lessons.

At age five, his father showed him a pocket compass, and Einstein realized that something in "empty" space acted upon the needle; he would later describe the experience as one of the most revelatory of his life. Though he built models and mechanical devices for fun, he was considered a slow learner, possibly due to dyslexia, simple shyness, or the significantly rare and unusual structure of his brain (examined after his death). He later credited his development of the theory of relativity to this slowness, saying that by pondering space and time later than most children, he was able to apply a more developed intellect. Another, more recent, theory about his mental development is that he had Asperger's syndrome, a condition related to autism.

Einstein began to learn mathematics around age twelve. There is a recurring rumor that he failed mathematics later in his education, but this is untrue; a change in the way grades were assigned caused confusion years later. Two of his uncles fostered his intellectual interests during his late childhood and early adolescence by suggesting and providing books on science and mathematics.

In 1894, following the failure of Hermann's electrochemical business, the Einsteins moved from Munich to Pavia, Italy (near Milan). During this year, Einstein's first scientific work was written (called "The Investigation of the State of Aether in Magnetic Fields"). Albert remained behind in Munich lodgings to finish school, completing only one term before leaving the gymnasium in spring 1895, before rejoining his family in Pavia. He quit without telling his parents and a year and a half prior to final examinations, Einstein convinced the school to let him go with a medical note from a friendly doctor, but this meant he had no secondary-school certificate.

Despite excelling in the mathematics and science portion, his failure of the liberal arts portion of the Eidgenössische Technische Hochschule (Swiss Federal Institute of Technology, in Zurich) entrance exam the following year was a setback; his family sent him to Aarau, Switzerland, to finish secondary school, where he received his diploma in September 1896. During this time he lodged with Professor Jost Winteler's family and became enamoured with Marie, their daughter, his first sweetheart. Albert's sister Maja was to later marry their son Paul, and his friend Michele Besso married their other daughter Anna. Einstein subsequently enrolled at the Eidgenössische Technische Hochschule in October and moved to Zurich, while Marie moved to Olsberg for a teaching post. The same year, he renounced his Württemberg citizenship, becoming stateless.


Einsteins wife Mileva with her sons Eduard and Hans Albert

In the spring of 1896, the Serbian Mileva Marić (an acquaintance of Nikola Tesla) started initially as a medical student at the University of Zurich, but after a term switched to the same section as Einstein, and as the only woman that year, to study for the same diploma. Einstein's relationship with Mileva developed into romance over the next few years.

In 1900, he was granted a teaching diploma by the Eidgenössische Technische Hochschule and was accepted as a Swiss citizen in 1901. During this time Einstein discussed his scientific interests with a group of close friends, including Mileva. He and Mileva had a daughter Lieserl, born in January 1902. Lieserl, at the time, was considered illegitimate because the parents were unwed.

Work and doctorate



Einstein, in 1905, when he wrote the "Annus Mirabilis Papers"

Upon graduation, Einstein could not find a teaching post, mostly because his brashness as a young man had apparently irritated most of his professors. The father of a classmate helped him obtain employment as a technical assistant examiner at the Swiss Patent Office [3] in 1902. There, Einstein judged the worth of inventors' patent applications for devices that required a knowledge of physics to understand. He also learned how to discern the essence of applications despite sometimes poor descriptions, and was taught by the director how "to express myself correctly". He occasionally rectified their design errors while evaluating the practicality of their work.

Einstein married Mileva Marić on January 6, 1903. Einstein's marriage to Marić, who was a mathematician, was both a personal and intellectual partnership: Einstein referred to Mileva as "a creature who is my equal and who is as strong and independent as I am". Ronald W. Clark, a biographer of Einstein, claimed that Einstein depended on the distance that existed in his and Mileva's marriage in order to have the solitude necessary to accomplish his work. Abram Joffe, a Soviet physicist who knew Einstein, in an obituary of Einstein, wrote, "The author of [the papers of 1905] was ... a bureaucrat at the Patent Office in Bern, Einstein-Marić" and this has recently been taken as evidence of a collaborative relationship. However, according to Alberto A. Martínez of the Center for Einstein Studies at Boston University, Joffe only ascribed authorship to Einstein, as he believed that it was a Swiss custom at the time to append the spouse's last name to the husband's name.[4] Whatever the truth, the extent of her influence on Einstein's work is a highly controversial and debated question.

On May 14, 1904, the couple's first son, Hans Albert Einstein, was born. In 1904, Einstein's position at the Swiss Patent Office was made permanent. He obtained his doctorate after submitting his thesis "A new determination of molecular dimensions" ("Eine neue Bestimmung der Moleküldimensionen") in 1905.

That same year, he wrote four articles that provided the foundation of modern physics, without much scientific literature to which he could refer or many scientific colleagues with whom he could discuss the theories. Most physicists agree that three of those papers (on Brownian motion, the photoelectric effect, and special relativity) deserved Nobel Prizes. Only the paper on the photoelectric effect would win one. This is ironic, not only because Einstein is far better-known for relativity, but also because the photoelectric effect is a quantum phenomenon, and Einstein became somewhat disenchanted with the path quantum theory would take. What makes these papers remarkable is that, in each case, Einstein boldly took an idea from theoretical physics to its logical consequences and managed to explain experimental results that had baffled scientists for decades.

Annus Mirabilis Papers

For a more detailed treatment of this topic, see the subarticle Annus Mirabilis Papers.



Max Planck and Einstein

Einstein submitted the series of papers to the "Annalen der Physik". They are commonly referred to as the "Annus Mirabilis Papers" (from Annus mirabilis, Latin for 'year of wonders'). The International Union of Pure and Applied Physics (IUPAP) plans to commemorate the 100th year of the publication of Einstein's extensive work in 1905 as the 'World Year of Physics 2005'.


Photoelectric effect, Physicist / Astronomers Stamps

The first paper, named "On a Heuristic Viewpoint Concerning the Production and Transformation of Light", ("Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt") proposed the idea of "energy quanta" (which underlies the concept of what are now called photons) and showed how it could be used to explain such phenomena as the photoelectric effect.

His second article in 1905, named "On the Motion—Required by the Molecular Kinetic Theory of Heat—of Small Particles Suspended in a Stationary Liquid", ("Über die von der molekularkinetischen Theorie der Wärme geforderte Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen") covered his study of Brownian motion, and provided empirical evidence for the existence of atoms.

Einstein's third paper that year, "On the Electrodynamics of Moving Bodies" ("Zur Elektrodynamik bewegter Körper"), was published on June 30, 1905. While developing this paper, Einstein wrote to Mileva about "our work on relative motion", and this has led some to ask whether Mileva played a part in its development. This paper introduced the special theory of relativity, a theory of time, distance, mass and energy which was consistent with electromagnetism, but omitted the force of gravity.

A fourth paper, "Does the Inertia of a Body Depend Upon Its Energy Content?", ("Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig?") published late in 1905, showed one further deduction from relativity's axioms, the famous equation that the energy of a body at rest (E) equals its mass (m) times the speed of light (c) squared.

Middle years


Marcel Grossmann

In 1906, Einstein was promoted to technical examiner second class. In 1908, Einstein was licensed in Bern, Switzerland, as a Privatdozent (unsalaried teacher at a university). Einstein's second son, Eduard, was born on July 28, 1910. In 1911, Einstein became first associate professor at the University of Zurich, and shortly afterwards full professor at the (German) University of Prague, only to return the following year to Zurich in order to become full professor at the ETH Zurich. At that time, he worked closely with the mathematician Marcel Grossman. In 1912, Einstein started to refer to time as the fourth dimension.

In 1914, just before the start of World War I, Einstein settled in Berlin as professor at the local university and became a member of the Prussian Academy of Sciences. He took German citizenship. His pacifism and Jewish origins irritated German nationalists. After he became world-famous, nationalistic hatred of him grew and for the first time he was the subject of an organized campaign to discredit his theories. From 1914 to 1933, he served as director of the Kaiser Wilhelm Institute for Physics in Berlin, and it was during this time that he was awarded his Nobel Prize and made his most groundbreaking discoveries.

Einstein divorced Mileva on February 14, 1919, and married his cousin Elsa Löwenthal (née Einstein: Löwenthal was the surname of her first husband, Max) on June 2, 1919. Elsa was Albert's first cousin (maternally) and his second cousin (paternally). She was three years older than Albert, and had nursed him to health after he had suffered a partial nervous breakdown combined with a severe stomach ailment. There were no children from this marriage. The fate of Albert and Mileva's first child, Lieserl, is unknown: some believe she died in infancy, while others believe she was given out for adoption. Eduard was institutionalized for schizophrenia and died in an asylum, while Hans became a professor of hydraulic engineering at the University of California, Berkeley, having little interaction with his father. In 1922, Einstein and his wife Elsa boarded the SS Kitano Maru bound for Japan. The trip also took them to other ports including Singapore, Hong Kong and Shanghai.

General relativity



"Einstein theory triumphs," declared the New York Times on November 10, 1919.

In November 1915, Einstein presented a series of lectures before the Prussian Academy of Sciences in which he described his theory of general relativity. The final lecture climaxed with his introduction of an equation that replaced Newton's law of gravity. This theory considered all observers to be equivalent, not only those moving at a uniform speed. In general relativity, gravity is no longer a force (as it is in Newton's law of gravity) but is a consequence of the curvature of space-time.

The theory provided the foundation for the study of cosmology and gave scientists the tools for understanding many features of the universe that were discovered well after Einstein's death. A truly revolutionary theory, general relativity has so far passed every test posed to it — unlike many other scientific theories — and become a method of perceiving all of physics.

Initially, scientists were skeptical because the theory was derived by mathematical reasoning and rational analysis, not by experiment or observation. But in 1919, predictions made using the theory were confirmed by Arthur Eddington's measurements (during a solar eclipse), of how much the light emanating from a star was bent by the Sun's gravity when it passed close to the Sun. On November 7, The Times reported the confirmation, cementing Einstein's fame.

However, many scientists were still unconvinced for various reasons, ranging from disagreement with Einstein's interpretation of the experiments, to not being able to tolerate the absence of an absolute frame of reference. In Einstein's view, many of them simply could not understand the mathematics involved. Einstein's public fame which followed the 1919 article created resentment among these scientists, some of which lasted well into the 1930s.

In the early 1920s, Einstein was the lead figure in a famous weekly physics colloquium at the University of Berlin. On March 30, 1921, Einstein went to New York to give a lecture on his new theory. In the same year, he was finally awarded the Nobel Prize. Though he is now most famous for his work on relativity, it was for his earlier work on the photoelectric effect that he was given the Prize, because his work on relativity was still disputed and the Nobel committee decided that citing his less-contested theory would be a better political move.

The "Copenhagen" interpretation

Einstein's relationship with quantum physics was quite remarkable. He was the first to say that quantum theory was revolutionary. His idea of light quanta, now known as photons, marked a landmark break with the classical physics. In 1909, Einstein presented his first paper to a gathering of physicists and told them that they must find some way to understand waves and particles together.

In the mid-1920s, as the original quantum theory was replaced with a new quantum mechanics, Einstein balked at the Copenhagen interpretation of the new equations because it settled for a probabilistic, non-visualizable account of physical behavior. Einstein agreed that the theory was the best available, but he looked for a more "complete" explanation, i.e., more deterministic. He could not abandon the belief that physics described the laws that govern "real things", the belief which had led to his successes with atoms, photons, and gravity.

In a 1926 letter to Max Born, Einstein made a remark that is now famous:

Quantum mechanics is certainly imposing. But an inner voice tells me it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the Old One. I, at any rate, am convinced that He does not throw dice.

To this, Bohr, who sparred with Einstein on quantum theory, retorted, "Stop telling God what He must do!" The Bohr-Einstein debates on foundational aspects on quantum mechanics happened during the Solvay conferences.

It was not a rejection of probabilistic theories per se—Einstein had used statistical analysis in his work on Brownian motion and photoelectricity, and in papers published before the miraculous year 1905, and had even discovered Gibbs ensembles on his own—but he believed that, at the core, physical reality behaved deterministically. Experimental evidence against this belief has been found only much later with the discovery of Bell's Theorem and Bell's inequality. However, there is still space for controversial discussions about the interpretation of quantum mechanics.

Bose-Einstein statistics

In 1924, Einstein received a short paper from a young Indian physicist named Satyendra Nath Bose describing light as a gas of photons and asking for Einstein's assistance in publication. Einstein realized that the same statistics could be applied to atoms, and published an article in German (then the lingua franca of physics) which described Bose's model and explained its implications. Bose-Einstein statistics now describe any assembly of these indistinguishable particles known as bosons. The Bose-Einstein condensate phenomenon was predicted in the 1920s by Bose and Einstein, based on Bose's work on the statistical mechanics of photons, which was then formalized and generalized by Einstein. The first such condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of Colorado at Boulder.

Einstein also assisted Erwin Schrödinger in the development of the Quantum Boltzmann distribution, a mixed classical and quantum mechanical gas model—although he realized that this was less significant than the Bose-Einstein model, and declined to have his name included on the paper.

Later years



Einstein and Szilárd's patent diagram.

Einstein and former student Leó Szilárd co-invented a unique type of refrigerator (usually called the Einstein Refrigerator) in 1926. [5] [6] On November 11, 1930, U.S. Patent 1,781,541 was awarded to Albert Einstein and Leó Szilárd. The patent covered a thermodynamic refrigeration cycle providing cooling with no moving parts, at a constant pressure, with only heat as an input. The refrigeration cycle used ammonia, butane, and water.

After Adolf Hitler came to power in 1933, expressions of hatred for Einstein reached new levels. He was accused by the National Socialist regime of creating "Jewish physics" in contrast with Deutsche Physik—German or "Aryan physics". Nazi physicists (notably including the Nobel laureates Johannes Stark and Philipp Lenard) continued the attempts to discredit his theories and to blacklist politically those German physicists who taught them (such as Werner Heisenberg). Einstein renounced his German citizenship and fled to the United States, where he was given permanent residency. He accepted a position at the newly founded Institute for Advanced Study in Princeton Township, New Jersey. He became an American citizen in 1940, though he still retained Swiss citizenship.

Einstein spent the last fourteen years of his life trying to unify gravity and electromagnetism, giving a new subtle understanding of quantum mechanics. He was looking for a classical unification of gravity and electromagnetism.

Institute for Advanced Study

His work at the Institute for Advanced Study focused on the unification of the laws of physics, which he referred to as the Unified Field Theory. He attempted to construct a model, under the appropriate conditions, which described all of the fundamental forces as different manifestations of a single force. His attempt was in a way doomed to failure because the strong and weak nuclear forces were not understood independently until around 1970, fifteen years after Einstein's death. Einstein's goal survives in the current drive for unification of the forces, embodied most notably by string theory.

Generalized theory

Einstein began to form a generalized theory of gravitation with the universal law of gravitation and the electromagnetic force in his first attempt to demonstrate the unification and simplification of the fundamental forces. In 1950, he described his work in a Scientific American article. Einstein was guided by a belief in a single statistical measure of variance for the entire set of physical laws, and he investigated the similar properties of the electromagnetic and gravity forces, as they are infinite and obey inverse-square laws.

Einstein's generalized theory of gravitation is a universal mathematical approach to field theory. He investigated reducing the different phenomena by the process of logic to something already known or evident. Einstein tried to unify gravity and electromagnetism in a way that also led to a new subtle understanding of quantum mechanics.

Einstein assumed a four-dimensional space-time continuum expressed in axioms represented by five component vectors. Particles appear in his research as a limited region in space in which the field strength or the energy density are particularly high. Einstein treated subatomic particles as objects embedded in the unified field, influencing it and existing as an essential constituent of the unified field but not of it. Einstein also investigated a natural generalization of symmetrical tensor fields, treating the combination of two parts of the field as being a natural procedure of the total field and not the symmetrical and antisymmetrical parts separately. He researched a way to delineate the equations and systems to be derived from a variational principle.

Einstein became increasingly isolated in his research on a generalized theory of gravitation and was ultimately unsuccessful in his attempts.

Final years



Einstein's two-story house, white frame with front porch in Greek revival style, in Princeton (112 Mercer Street).

In 1948, Einstein served on the original committee which resulted in the founding of Brandeis University. A portrait of Einstein was taken by Yousuf Karsh on February 11 of that same year. In 1952, the Israeli government proposed to Einstein that he take the post of second president. He declined the offer, and remains the only United States citizen to ever be offered a position as a foreign head of state. On March 30, 1953, Einstein released a revised unified field theory.

He died in his sleep at a hospital in Princeton, New Jersey, on April 18, 1955, leaving the Generalized Theory of Gravitation unsolved. The only person present at his deathbed, a hospital nurse, said that just before his death he mumbled several words in German that she did not understand. He was cremated without ceremony on the same day he died at Trenton, New Jersey, in accordance with his wishes. His ashes were scattered at an undisclosed location.

His brain was preserved in a jar by Dr. Thomas Stoltz Harvey, the pathologist who performed the autopsy on Einstein. Harvey found nothing unusual with his brain, but in 1999 further analysis by a team at McMaster University revealed that his parietal operculum region was missing and, to compensate, his inferior parietal lobe was 15% wider than normal [7]. The inferior parietal region is responsible for mathematical thought, visuospatial cognition, and imagery of movement.

Personality


Albert Einstein Stamps

Albert Einstein was much respected for his kind and friendly demeanor rooted in his pacifism. He was modest about his abilities, and had distinctive attitudes and fashions—for example, he minimized his wardrobe so that he would not need to waste time in deciding on what to wear. He occasionally had a playful sense of humor, and enjoyed sailing and playing the violin. He was also the stereotypical "absent-minded professor"; he was often forgetful of everyday items, such as keys, and would focus so intently on solving physics problems that he would often become oblivious to his surroundings.

Religious views

Although he was raised Jewish, he was not a believer in Judaism. He simply admired the beauty of nature and the universe. From a letter written in English, dated March 24, 1954, Einstein wrote, "It was, of course, a lie what you read about my religious convictions, a lie which is being systematically repeated. I do not believe in a personal God and I have never denied this but have expressed it clearly. If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it."

He also said (in an essay reprinted in Living Philosophies, vol. 13 (1931)): "A knowledge of the existence of something we cannot penetrate, our perceptions of the profoundest reason and the most radiant beauty, which only in their most primitive forms are accessible to our minds - it is this knowledge and this emotion that constitute true religiosity; in this sense, and this alone, I am a deeply religious man."

The following is a response made to Rabbi Herbert Goldstein of the International Synagogue in New York which read, "I believe in Spinoza's God who reveals himself in the orderly harmony of what exists, not in a God who concerns himself with the fates and actions of human beings." After being pressed on his religious views by Martin Buber, Einstein exclaimed, "What we [physicists] strive for is just to draw His lines after Him." Summarizing his religious beliefs, he once said: "My religion consists of a humble admiration of the illimitable superior spirit who reveals himself in the slight details we are able to perceive with our frail and feeble mind."

He also expressed admiration for Buddhism, which he said "has the characteristics of what would be expected in a cosmic religion for the future: It transcends a personal God, avoids dogmas and theology; it covers both the natural and the spiritual, and it is based on a religious sense aspiring from the experience of all things, natural and spiritual, as a meaningful unity."

Victor J. Stenger, author of Has Science Found God? (2001), wrote of Einstein's presumed pantheism, "Both deism and traditional Judeo-Christian-Islamic theism must also be contrasted with pantheism, the notion attributed to Baruch Spinoza that the deity is associated with the order of nature or the universe itself. This also crudely summarizes the Hindu view and that of many indigenous religions around the world. When modern scientists such as Einstein and Stephen Hawking mention 'God' in their writings, this is what they seem to mean: that God is Nature."

He was a fond lover of Mahatma Gandhi and his political views.

Political views

Einstein considered himself a pacifist [8] and humanitarian [9], and in later years, a committed democratic socialist. He once said, "I believe Gandhi's views were the most enlightened of all the political men of our time. We should strive to do things in his spirit: not to use violence for fighting for our cause, but by non-participation of anything you believe is evil." Einstein's views on other issues, including socialism, McCarthyism and racism, were controversial (see Einstein on socialism). Einstein was a co-founder of the liberal German Democratic Party.

The U.S. FBI kept a 1,427 page file on his activities and recommended that he be barred from immigrating to the United States under the Alien Exclusion Act, alleging that Einstein "believes in, advises, advocates, or teaches a doctrine which, in a legal sense, as held by the courts in other cases, 'would allow anarchy to stalk in unmolested' and result in 'government in name only'", among other charges. They also alleged that Einstein "was a member, sponsor, or affiliated with thirty-four communist fronts between 1937-1954" and "also served as honorary chairman for three communist organizations."[10]

Einstein opposed tyrannical forms of government, and for this reason (and his Jewish background), opposed the Nazi regime and fled Germany shortly after it came to power. He initially favored construction of the atomic bomb, in order to ensure that Hitler did not do so first, and even sent a letter [11] to President Roosevelt (dated August 2, 1939, before World War II broke out, and likely authored by Leó Szilárd) encouraging him to initiate a program to create a nuclear weapon. Roosevelt responded to this by setting up a committee for the investigation of using uranium as a weapon, which in a few years was superseded by the Manhattan Project.

After the war, though, Einstein lobbied for nuclear disarmament and a world government: "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones."

Einstein was a supporter of Zionism. He supported Jewish settlement of the ancient seat of Judaism and was active in the establishment of the Hebrew University in Jerusalem, which published (1930) a volume titled About Zionism: Speeches and Lectures by Professor Albert Einstein, and to which Einstein bequeathed his papers. However, he opposed nationalism and expressed skepticism about whether a Jewish nation-state was the best solution. He may have imagined Jews and Arabs living peacefully in the same land. In later life he was offered the post of second president of the newly created state of Israel, but declined the offer, claiming that he lacked the necessary people skills.

Einstein, along with Albert Schweitzer and Bertrand Russell, fought against nuclear tests and bombs. As his last public act, and just days before his death, he signed the Russell-Einstein Manifesto, which led to the Pugwash Conferences on Science and World Affairs. His letter to Russell read:

Dear Bertrand Russell,

Thank you for your letter of April 5. I am gladly willing to sign your excellent statement. I also agree with your choice of the prospective signers.

With kind regards, A. Einstein

Popularity and cultural impact

Einstein's popularity has led to widespread use of Einstein in advertising and merchandising, including the registration of "Albert Einstein" as a trademark.


"He who joyfully marches to music in rank and file has already earned my contempt. He has been given a large brain by mistake, since for him the spinal cord would fully suffice. This disgrace to civilization should be done away with at once. Heroism at command, senseless brutality, and all the loathsome nonsense that goes by the name of patriotism, how violently I hate all this, how despicable and ignoble war is; I would rather be torn to shreds than be part of so base an action! It is my conviction that killing under the cloak of war is nothing but an act of murder."

The photo (detail from the original) of this humorous expression was taken during Einstein's birthday on March 14, 1951, UPI

Entertainment

Albert Einstein has become the subject of a number of novels, films and plays, including Nicolas Roeg's film Insignificance, Fred Schepisi's film I.Q., Alan Lightman's novel Einstein's Dreams, and Steve Martin's comedic play "Picasso at the Lapin Agile". He was the subject of Philip Glass's groundbreaking 1976 opera Einstein on the Beach. Since 1978, Einstein's humorous side has been the subject of a live stage presentation Albert Einstein: The Practical Bohemian, a one man show performed by actor Ed Metzger.

He is often used as a model for depictions of eccentric scientists in works of fiction; his own character and distinctive hairstyle suggest eccentricity, electricity, or even lunacy and are widely copied or exaggerated.

On Einstein's 72nd birthday in 1951, the UPI photographer Arthur Sasse was trying to coax him into smiling for the camera. Having done this for the photographer many times that day, Einstein stuck out his tongue instead [12]. The image has become an icon in pop culture for its contrast of the genius scientist displaying a moment of levity. Yahoo Serious, an Australian film maker, used the photo as an inspiration for the intentionally anachronistic movie Young Einstein.

Licensing

The Roger Richman Agency, Inc. licences the commercial use of the name "Albert Einstein" and associated imagery and likenesses of Einstein, as agent for the Hebrew University of Jerusalem. Einstein actively supported the university during his life and this support continues with the royalties received from licensing activities. As head licensee the agency can control commercial usage of Einstein's name which does not comply with certain standards (e.g., when Einstein's name is used as a trademark, the ™ symbol must be used [13]).

Honors

Einstein has received a number of posthumous honors, including:


100 Years Relativity - Atoms- Quanta, 2005 German Stamp


in 1999, he was named "Person of the Century" by TIME magazine.

the year 2005 was designated as the "World Year of Physics" by UNESCO for its coinciding with the centennial of the "Annus Mirabilis" papers, celebrated at the Einstein Symposium.

Among Einstein's many namesakes are:

* a unit used in photochemistry, the einstein.
* the chemical element 99, einsteinium.
* the asteroid 2001 Einstein.
* the Albert Einstein Peace Prize.
* the Albert Einstein College of Medicine of Yeshiva University was named after Einstein upon his death in 1955.

Monday, May 23, 2011

ORACLE DATABASE

PHYSICAL AND LOGICAL STRUCTURES


An Oracle database system—identified by an alphanumeric system identifier or SID[4]—comprises at least one instance of the application, along with data storage. An instance—identified persistently by an instantiation number (or activation id: SYS.V_$DATABASE.ACTIVATION#)—comprises a set of operating-system processes and memory-structures that interact with the storage. Typical processes include PMON (the process monitor) and SMON (the system monitor).

Users of the Oracle databases refer to the server-side memory-structure as the SGA (System Global Area). The SGA typically holds cache information such as data-buffers, SQL commands, and user information. In addition to storage, the database consists of online redo logs (or logs), which hold transactional history. Processes can in turn archive the online redo logs into archive logs (offline redo logs), which provide the basis (if necessary) for data recovery and for some forms of data replication.

If the Oracle database administrator has implemented Oracle RAC (Real Application Clusters), then multiple instances, usually on different servers, attach to a central storage array. This scenario offers advantages such as better performance, scalability and redundancy. However, support becomes more complex, and many sites do not use RAC. In version 10g, grid computing introduced shared resources where an instance can use (for example) CPU resources from another node (computer) in the grid.

The Oracle DBMS can store and execute stored procedures and functions within itself. PL/SQL (Oracle Corporation's proprietary procedural extension to SQL), or the object-oriented language Java can invoke such code objects and/or provide the programming structures for writing them.
[edit] Storage

The Oracle RDBMS stores data logically in the form of tablespaces and physically in the form of data files ("datafiles").[5] Tablespaces can contain various types of memory segments, such as Data Segments, Index Segments, etc. Segments in turn comprise one or more extents. Extents comprise groups of contiguous data blocks. Data blocks form the basic units of data storage.

There is also a partitioning feature available on newer versions of the database, which allows tables to be partitioned based on different set of keys. Specific partitions can then be easily added or dropped to help manage large data sets.

Oracle database management tracks its computer data storage with the help of information stored in the SYSTEM tablespace. The SYSTEM tablespace contains the data dictionary—and often (by default) indexes and clusters. A data dictionary consists of a special collection of tables that contains information about all user-objects in the database. Since version 8i, the Oracle RDBMS also supports "locally managed" tablespaces which can store space management information in bitmaps in their own headers rather than in the SYSTEM tablespace (as happens with the default "dictionary-managed" tablespaces). Version 10i and later introduced the SYSAUX tablespace which contains some of the tables formerly in the SYSTEM tablespace.
Disk files

Disk files primarily consist of the following types:

* Data and index files
* Redo log files consisting of all changes to the database, used to recover from an instance failure
* Undo files used for recovery, rollbacks, and read consistency
* Archive log files
* Temporary files
* Control files containing information on data files

At the physical level, data files comprise one or more data blocks, where the block size can vary between data files.

Data files can occupy pre-allocated space in the file system of a computer server, utilize raw disk directly, or exist within ASM logical volumes.[6]
[edit] Control files

The following parameters govern the size of the control files:

* maxlogfile
* maxlogmembers
* maxloghistory
* maxinstances
* control_file_record_keep_time

Database Schema

Oracle database conventions refer to defined groups of object ownership (generally associated with a "username") as schemas.

Most Oracle database installations traditionally came with a default schema called SCOTT. After the installation process has set up the sample tables, the user can log into the database with the username scott and the password tiger. The name of the SCOTT schema originated with Bruce Scott, one of the first employees at Oracle (then Software Development Laboratories), who had a cat named Tiger.[7]

Oracle Corporation has de-emphasized the use of the SCOTT schema, as it uses few of the features of the more recent releases of Oracle. Most recent[update] examples supplied by Oracle Corporation reference the default HR or OE schemas.

Other default schemas[8][9] include:

* SYS (essential core database structures and utilities)
* SYSTEM (additional core database structures and utilities, and privileged account)
* OUTLN (utilized to store metadata for stored outlines for stable query-optimizer execution plans.[10]
* BI, IX, HR, OE, PM, and SH (expanded sample schemas[11] containing more data and structures than the older SCOTT schema).

System Global Area
Main article: System Global Area

Each Oracle instance uses a System Global Area or SGA—a shared-memory area—to store its data and control-information.[12]

Each Oracle instance allocates itself an SGA when it starts and de-allocates it at shut-down time. The information in the SGA consists of the following elements, each of which has a fixed size, established at instance startup:

* the redo log buffer: this stores redo entries—a log of changes made to the database. The instance writes redo log buffers to the redo log as quickly and efficiently as possible. The redo log aids in instance recovery in the event of a system failure.
* the shared pool: this area of the SGA stores shared-memory structures such as shared SQL areas in the library cache and internal information in the data dictionary. An insufficient amount of memory allocated to the shared pool can cause performance degradation.

Library cache

The library cache[13] stores shared SQL, caching the parse tree and the execution plan for every unique SQL statement. If multiple applications issue the same SQL statement, each application can access the shared SQL area. This reduces the amount of memory needed and reduces the processing-time used for parsing and execution planning.
Data dictionary cache

The data dictionary comprises a set of tables and views that map the structure of the database.

Oracle databases store information here about the logical and physical structure of the database. The data dictionary contains information such as:

* user information, such as user privileges
* integrity constraints defined for tables in the database
* names and datatypes of all columns in database tables
* information on space allocated and used for schema objects

The Oracle instance frequently accesses the data dictionary in order to parse SQL statements. The operation of Oracle depends on ready access to the data dictionary: performance bottlenecks in the data dictionary affect all Oracle users. Because of this, database administrators should make sure that the data dictionary cache[14] has sufficient capacity to cache this data. Without enough memory for the data-dictionary cache, users see a severe performance degradation. Allocating sufficient memory to the shared pool where the data dictionary cache resides precludes these particular performance problems.
[edit] Program Global Area

The Program Global Area[15][16] or PGA memory-area of an Oracle instance contains data and control-information for Oracle's server-processes.

The size and content of the PGA depends on the Oracle-server options installed. This area consists of the following components:

* stack-space: the memory that holds the session's variables, arrays, and so on.
* session-information: unless using the multithreaded server, the instance stores its session-information in the PGA. (In a multithreaded server, the session-information goes in the SGA.)
* private SQL-area: an area in the PGA which holds information such as bind-variables and runtime-buffers.
* sorting area: an area in the PGA which holds information on sorts, hash-joins, etc.

Dynamic performance views

The dynamic performance views (also known as "fixed views") within an Oracle database present information from virtual tables (X$ tables[17]) built on the basis of database memory.[18] Database users can access the V$ views (named after the prefix of their synonyms) to obtain information on database structures and performance.
Process architectures
Oracle processes

The Oracle RDBMS typically relies on a group of processes running simultaneously in the background and interacting to monitor and expedite database operations. Typical operating environments might include some of the following individual processes (shown along with their abbreviated nomenclature):[19]

* advanced queueing processes (Qnnn)[20]
* archiver processes (ARCn)
* checkpoint process (CKPT) *REQUIRED*
* coordinator-of-job-queues process (CJQn): dynamically spawns slave processes for job-queues
* database writer processes (DBWn) *REQUIRED*
* dispatcher processes (Dnnn): multiplex server-processes on behalf of users
* job-queue slave processes (Jnnn)[21]
* log-writer process (LGWR) *REQUIRED*
* log-write network-server (LNSn): transmits redo logs in Data Guard environments
* logical standby coordinator process (LSP0): controls Data Guard log-application
* media-recovery process (MRP): detached recovery-server process
* memory-manager process (MMAN): used for internal database tasks such as Automatic Shared Memory Management
* memory-monitor process (MMON): process for automatic problem-detection, self-tuning and statistics-gathering[22]
* memory-monitor light process (MMNL): gathers and stores Automatic Workload Repository (AWR) data
* mmon slaves (Mnnnn—M0000, M0001, etc.): background slaves of the MMON process[23]
* process-monitor process (PMON) *REQUIRED*
* process-spawner (PSP0): spawns Oracle processes
* queue-monitor coordinator process (QMNC): dynamically spwans queue monitor slaves[24]
* queue-monitor processes (QMNn)
* recoverer process (RECO)
* remote file-server process (RFS)
* shared server processes (Snnn): serve client-requests
* system monitor process (SMON) *REQUIRED*

User processes, connections and sessions

Oracle Database terminology distinguishes different computer-science terms in describing how end-users interact with the database:

* user processes involve the invocation of application software[25]
* a connection refers to the pathway linking a user process to an Oracle instance[26]
* sessions consist of specific connections to an Oracle instance.[27] Each session within an instance has a session identifier or "SID"[28] (distinct from the system-identifier SID).

Concurrency and locking

Oracle databases control simultaneous access to data resources with locks (alternatively documented as "enqueues"[29] ). The databases also utilize "latches" -- low-level serialization mechanisms to protect shared data structures in the System Global Area.[30]
[edit] Configuration

Database administrators control many of the tunable variations in an Oracle instance by means of values in a parameter file.[31] This file in its ASCII default form ("pfile") normally has a name of the format init.ora. The default binary equivalent server paramater file ("spfile") (dynamically reconfigurable to some extent)[32] defaults to the format spfile.ora. Within an SQL-based environment, the views V$PARAMETER[33] and V$SPPARAMETER[34] give access to reading parameter values.
Internationalization

Oracle Database software comes in 63 language-versions (including regional variations such as British English and American English). Variations between versions cover the names of days and months, abbreviations, time-symbols such as A.M. and A.D., and sorting.[35]

Oracle Corporation has translated Oracle Database error-messages into Arabic, Catalan, Chinese, Czech, Danish, Dutch, English, Finnish, French, German, Greek, Hebrew, Hungarian, Italian, Japanese, Korean, Norwegian, Polish, Portuguese, Romanian, Russian, Slovak, Spanish, Swedish, Thai and Turkish.[36]

Oracle Corporation provides database developers with tools and mechanisms for producing internationalized database applications: referred to internally as "Globalization". [37] ".[38]
History
Corporate/technical timeline

* 1977: Larry Ellison and friends founded Software Development Laboratories.
* 1979: SDL changed its company-name to "Relational Software, Inc." (RSI) and introduced its product Oracle V2 as an early commercially available relational database system. The version did not support transactions, but implemented the basic SQL functionality of queries and joins. (RSI never released a version 1 - instead calling the first version version 2 as a marketing gimmick.)[39]
* 1982: RSI in its turn changed its name, becoming known as "Oracle Corporation",[40] to align itself more closely with its flagship product.
* 1983: The company released Oracle version 3, which it had re-written using the C programming language and which supported COMMIT and ROLLBACK functionality for transactions. Version 3 extended platform support from the existing Digital VAX/VMS systems to include Unix environments.[40]
* 1984: Oracle Corporation released Oracle version 4, which supported read-consistency.
* 1985: Oracle Corporation released Oracle version 5, which supported the client–server model—a sign of networks becoming more widely available in the mid-1980s.
* 1986: Oracle version 5.1 started supporting distributed queries.
* 1988: Oracle RDBMS version 6 came out with support for PL/SQL embedded within Oracle Forms v3 (version 6 could not store PL/SQL in the database proper), row-level locking and hot backups.[41]
* 1989: Oracle Corporation entered the application products market and developed its ERP product, (later to become part of the Oracle E-Business Suite), based on the Oracle relational database.
* 1990: the release of Oracle Applications release 8[40]
* 1992: Oracle version 7 appeared with support for referential integrity, stored procedures and triggers.
* 1997: Oracle Corporation released version 8, which supported object-oriented development and multimedia applications.
* 1999: The release of Oracle8i aimed to provide a database inter-operating better with the Internet (the i in the name stands for "Internet"). The Oracle8i database incorporated a native Java virtual machine (Oracle JVM, also known as "Aurora".[42]).
* 2000: Oracle E-Business Suite 11i pioneers integrated enterprise application software[40]
* 2001: Oracle9i went into release with 400 new features, including the ability to read and write XML documents. 9i also provided an option for Oracle RAC, or "Real Application Clusters", a computer-cluster database, as a replacement for the Oracle Parallel Server (OPS) option.
* 2003: Oracle Corporation released Oracle Database 10g, which supported regular expressions. (The g stands for "grid"; emphasizing a marketing thrust of presenting 10g as "grid computing ready".)
* 2005: Oracle Database 10.2.0.1—also known as Oracle Database 10g Release 2 (10gR2)—appeared.
* 2006: Oracle Corporation announces Unbreakable Linux[40]
* 2007: Oracle Database 10g release 2 sets a new world record TPC-H 3000 GB benchmark result[43]
* 2007: Oracle Corporation released Oracle Database 11g for Linux and for Microsoft Windows.
* 2008: Oracle Corporation acquires BEA Systems.
* 2010: Oracle Corporation acquires Sun Microsystems.

Version numbering

Oracle products have historically followed their own release-numbering and naming conventions. With the Oracle RDBMS 10g release, Oracle Corporation started standardizing all current versions of its major products using the "10g" label, although some sources continued to refer to Oracle Applications Release 11i as Oracle 11i. The suffixes of "i" and "g" do not actually represent a lower-order level of version numbering, as letters typically represent in software industry version numbering. That is, there is no predecessor version of Oracle 10g called Oracle 10f. Instead, the letters merely represent a marketing gimmick to demonstrate Oracle's focus on the "internet" and "grid", respectively. Consequently, many simply drop the letter suffix when referring to Oracle versions. Major database-related products and some of their versions include:

* Oracle Application Server 10g (also known as "Oracle AS 10g"): a middleware product;
* Oracle Applications Release 11i (aka Oracle e-Business Suite, Oracle Financials or Oracle 11i): a suite of business applications;
* Oracle Developer Suite 10g (9.0.4);
* Oracle JDeveloper 10g: a Java integrated development environment;

Since version 5, Oracle's RDBMS release numbering has used the following codes:

* Oracle v5
* Oracle v6
* Oracle7: 7.0.16—7.3.4
* Oracle8 Database: 8.0.3—8.0.6
* Oracle8i Database Release 1: 8.1.5.0—8.1.5.1
* Oracle8i Database Release 2: 8.1.6.0—8.1.6.3
* Oracle8i Database Release 3: 8.1.7.0—8.1.7.4
* Oracle9i Database Release 1: 9.0.1.0—9.0.1.5 (patchset as of December 2003[update])
* Oracle9i Database Release 2: 9.2.0.1—9.2.0.8 (patchset as of April 2007[update])
* Oracle Database 10g Release 1: 10.1.0.2—10.1.0.5 (patchset as of February 2006[update])
* Oracle Database 10g Release 2: 10.2.0.1—10.2.0.5 (patchset as of April 2010[update])
* Oracle Database 11g Release 1: 11.1.0.6—11.1.0.7 (patchset as of September 2008[update])
* Oracle Database 11g Release 2: 11.2.0.1—11.2.0.2 (patchset as of November 2010[update])

The version-numbering syntax within each release follows the pattern: major.maintenance.application-server.component-specific.platform-specific.

For example, "10.2.0.1 for 64-bit Solaris" means: 10th major version of Oracle, maintenance level 2, Oracle Application Server (OracleAS) 0, level 1 for Solaris 64-bit.

The Oracle Administrator's Guide offers further information on Oracle release numbers.
[edit] List of claimed firsts
Question book-new.svg
This article needs additional citations for verification.
Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (December 2007)

Oracle Corporation claims to have provided:

* the first commercially available SQL-based database (1979)[44]
* the first database to support symmetric multiprocessing (SMP) (1983)
* the first distributed database (1986)
* the first database product tested to comply with the ANSI SQL standard (1993)[44]
* the first 64-bit database (1995)
* the first database to incorporate a native JRE (1998)
* the first proprietary RDBMS to become available on Linux (1998)[45]
* the first database to support XML (1999)

Marketing editions

Over and above the different versions of the Oracle database management software developed over time, Oracle Corporation subdivides its product into varying "editions" - apparently for marketing and license-tracking reasons. (Do not confuse the marketing "editions" with the internal virtual versioning "editions" introduced with Oracle 11.2[46]). In approximate order of decreasing scale, we find:

* Enterprise Edition[47] (EE) includes more features than the 'Standard Edition', especially in the areas of performance and security. Oracle Corporation licenses this product on the basis of users or of processors, typically for servers running 4 or more CPUs. EE has no memory limits, and can utilize clustering using Oracle RAC software.
* Standard Edition[48] (SE) contains base database functionality. Oracle Corporation licenses this product on the basis of users or of processors, typically for servers running from one to four CPUs. If the number of CPUs exceeds 4 CPUs, the user must convert to an Enterprise license. SE has no memory limits, and can utilize clustering with Oracle RAC at no additional charge.
* Standard Edition One,[49] (SE1[50] or SEO) introduced with Oracle 10g, has some additional feature-restrictions. Oracle Corporation markets it for use on systems with one or two CPUs. It has no memory limitations.
* Express Edition[51] ("Oracle Database XE"), introduced in 2005, offers Oracle 10g free to distribute on Windows and Linux platforms. It has a footprint of only 150 MB and is restricted to the use of a single CPU, a maximum of 4 GB of user data. Although it can install on a server with any amount of memory, it uses a maximum of 1 GB.[52] Support for this version comes exclusively through on-line forums and not through Oracle support.
* Oracle Database Lite,[53] intended for running on mobile devices. The embedded[54] mobile database located on the mobile device can synchronize with a server-based installation.

Host platforms

Prior to releasing Oracle 9i in 2001, Oracle Corporation ported its database product to a wide variety of platforms. More recently Oracle Corporation has consolidated on a smaller range of operating-system platforms.

As of October 2006[update], Oracle Corporation supported the following operating systems and hardware platforms for Oracle Database 10g[citation needed]:

* Apple Mac OS X Server: PowerPC
* HP HP-UX: PA-RISC, Itanium
* HP Tru64 UNIX: Alpha
* HP OpenVMS: Alpha, Itanium
* IBM AIX5L: IBM POWER
* IBM z/OS: zSeries
* Linux: x86, x86-64, PowerPC, zSeries, Itanium
* Microsoft Windows: x86, x86-64, Itanium
* Sun Solaris: SPARC, x86, x86-64

Related software
Oracle products

* Oracle Database Firewall[55] analyzes database traffic on a network to prevent threats such as SQL injection.[56]

Database options

Oracle Corporation refers to some extensions to the core functionality of the Oracle database as "database options".[57] As of 2008[update] such options include:

* Active Data Guard (extends Oracle Data Guard physical standby functionality in 11g)
* Advanced Compression (compresses tables, backups and redo-data)[58]
* Advanced Security (adds data encryption methods)
* Content database (provides a centralized repository for unstructured information)
* Database Vault (enforces extra security on data access)
* Data Mining ( ODM) (mines for patterns in existing data)
* In-Memory Database Cache (utilizes TimesTen technology)
* Label Security (enforces row-level security)
* Management Packs (various). For example:
o Oracle Database Change Management Pack[59][60] (tracks and manages schema changes)
* Oracle Answers (for ad-hoc analysis and reporting)
* Oracle OLAP (adds analytical processing)
* Oracle Programmer (provides programmatic access to Oracle databases via precompilers, interfaces and bindings)[61]
* Partitioning (granularizes tables and indexes for efficiency)
* Real Application Clusters (RAC) (coordinates multiple database servers, together accessing the same database)
* Oracle Real Application Testing (new at version 11g)—including Database Replay (for testing workloads) and SQL Performance Analyzer (SPA) (for preserving SQL efficiency in changing environments)[62]
* Records database (a records management application)
* Oracle Spatial (integrates relational data with geographic information systems (GIS))
* Transparent Gateway for connecting to non-Oracle systems. Offers optimized solution, with more functionality and better performance than Oracle Generic Connectivity.
* Total Recall (optimizes long-term storage of historical data)
* Oracle Warehouse Builder (in various forms and sub-options)

This list is incomplete; you can help by expanding it.

In most cases, using these options entails extra licensing costs.[63]
Suites

In addition to its RDBMS, Oracle Corporation has released several related suites of tools and applications relating to implementations of Oracle databases. For example:

* Oracle Application Server, a J2EE-based application server, aids in developing and deploying applications which utilise Internet technologies and a browser.
* Oracle Collaboration Suite contains messaging, groupware and collaboration applications.
* Oracle Developer Suite contains software development tools, including JDeveloper.
* Oracle E-Business Suite collects together applications for enterprise resource planning (including Oracle Financials), customer relationship management and human resources management (Oracle HR).
* Oracle Enterprise Manager (OEM) used by database administrators (DBAs) to manage the DBMS, and recently[update] in version 10g, a web-based rewrite of OEM called "Oracle Enterprise Manager Database Control". Oracle Corporation has dubbed the super-Enterprise-Manager used to manage a grid of multiple DBMS and Application Servers "Oracle Enterprise Manager Grid Control".
* Oracle Programmer/2000, a bundling of interfaces for 3GL programming languages, marketed with Oracle7 and Oracle8.[64][65]
* Oracle WebCenter Suite[66]

Database "features"

Apart from the clearly defined database options, Oracle databases may include many semi-autonomous software sub-systems, which Oracle Corporation sometimes refers to as "features" in a sense subtly different from the normal usage of the word. For example, Oracle Data Guard counts officially as a "feature", but the command-stack within SQL*Plus, though a usability feature, does not appear in the list of "features" in Oracle's list.[original research?] Such "features" may include (for example):

* Active Session History (ASH), the collection of data for immediate monitoring of very recent database activity.[67]
* Automatic Workload Repository (AWR), providing monitoring services to Oracle database installations from Oracle version 10. Prior to the release of Oracle version 10, the Statspack facility[68] provided similar functionality.
* Clusterware
* Data Aggregation and Consolidation
* Data Guard for high availability
* Generic Connectivity for connecting to non-Oracle systems.
* Data Pump utilities, which aid in importing and exporting data and metadata between databases[69]
* Database Resource Manager (DRM), which controls the use of computing resources.[70]
* Fine-grained auditing (FGA) (in Oracle Enterprise Edition[71]) supplements standard security-auditing features[72]
* Flashback for selective data recovery and reconstruction[73]
* iSQL*Plus, a web-browser-based graphical user interface (GUI) for Oracle database data-manipulation (compare SQL*Plus)
* Oracle Data Access Components (ODAC), tools which consist of:[74]
o Oracle Data Provider for .NET (ODP.NET)[75]
o Oracle Developer Tools (ODT) for Visual Studio
o Oracle Providers for ASP.NET
o Oracle Database Extensions for .NET
o Oracle Provider for OLE DB
o Oracle Objects for OLE
o Oracle Services for Microsoft Transaction Server
* Oracle-managed files (OMF) -- a feature allowing automated naming, creation and deletion of datafiles at the operating-system level.
* Recovery Manager (rman) for database backup, restoration and recovery
* SQL*Plus, a program that allows users to interact with Oracle database(s) via SQL and PL/SQL commands on a command-line. Compare iSQL*Plus.
* Virtual Private Database[76] (VPD), an implementation of fine-grained access control.[77]

This list is incomplete; you can help by expanding it.

Standalone tools

Users can develop applications in Java and PL/SQL using tools such as Oracle JDeveloper, Oracle Forms, or Oracle Reports. Oracle Corporation has started[clarification needed] a drive toward 'wizard'-driven environments with a view to enabling non-programmers to produce simple data-driven applications.

Oracle SQL Developer, a free graphical tool for database development, allows developers to browse database objects, run SQL statements and SQL scripts, and edit and debug PL/SQL statements. It incorporates standard and customized reporting.
Other databases marketed by Oracle Corporation

By acquiring other technology in the database field, Oracle Corporation has taken over:

* TimesTen, a memory-resident database that can cache transactions and synchronize data with a centralized Oracle database server. It functions as a real-time infrastructure software product intended for the management of low-latency, high-volume data, of events and of transactions.
* BerkeleyDB, a simple, high-performance, embedded database
* Oracle Rdb, a legacy relational database for the OpenVMS operating system
* MySQL a relational database purchased as part of its immediate previous owner, Sun Microsystems

Use

The Oracle RDBMS has had a reputation among novice users as difficult to install on Linux systems.[citation needed] Oracle Corporation has packaged recent[update] versions for several popular Linux distributions in an attempt to minimize installation challenges beyond the level of technical expertise required to install a database server.[citation needed]
[edit] Official support

Users who have Oracle support contracts can use Oracle's "My Oracle Support" web site. The "My Oracle Support" site was known as MetaLink until a re-branding exercise completed in October 2010. The support site provides users of Oracle Corporation products with a repository of reported problems, diagnostic scripts and solutions. It also integrates with the provision of support tools, patches and upgrades.

The Remote Diagnostic Agent or RDA[78] can operate as a command-line diagnostic tool executing a script. The data captured provides an overview of the Oracle Database environment intended for diagnostic and trouble-shooting. Within RDA, the HCVE (Health Check Validation Engine)[79] can verify and isolate host system environmental issues that may affect the performance of Oracle software.
Database-related guidelines

Oracle Corporation also endorses certain practices and conventions as enhancing the use of its database products. These include:

* Oracle Maximum Availability Architecture (MAA), guidelines on developing high-availability systems
* Optimal Flexible Architecture (OFA), blueprints for mapping Oracle-database objects to file-systems

Oracle Certification Program
Main article: Oracle Certification Program

The Oracle Certification Program, a professional certification program, includes the administration of Oracle Databases as one of its main certification paths. It contains three levels:

1. Oracle Certified Associate (OCA)
2. Oracle Certified Professional (OCP)
3. Oracle Certified Master (OCM)

User groups

A variety of official (Oracle-sponsored) and unofficial Oracle User Groups has grown up of users and developers of Oracle databases. They include:

* Oracle Technology Network
* Independent Oracle Users Group
* Geographical/regional user groups
* Product-centric user groups
* Industry-centric user groups
* The Oak Table Network
* Usenet newsgroups

Market position
Competition

In the market for relational databases, Oracle Database competes against commercial products such as IBM's DB2 UDB and Microsoft SQL Server. Oracle and IBM tend to battle for the mid-range database market on UNIX and Linux platforms, while Microsoft dominates the mid-range database market on Microsoft Windows platforms. However, since they share many of the same customers, Oracle and IBM tend to support each other's products in many middleware and application categories (for example: WebSphere, PeopleSoft, and Siebel Systems CRM), and IBM's hardware divisions work closely[citation needed] with Oracle on performance-optimizing server-technologies (for example, Linux on zSeries). The two companies have a relationship perhaps[original research?] best described as "coopetition". Niche commercial competitors include Teradata (in data warehousing and business intelligence), Software AG's ADABAS, Sybase, and IBM's Informix, among many others.

In 2007, competition with SAP AG occasioned litigation from Oracle Corporation.[80]

Increasingly, the Oracle database products compete against such open-source software relational database systems as PostgreSQL, Firebird, and MySQL. Oracle acquired Innobase, supplier of the InnoDB codebase to MySQL, in part to compete better against open source alternatives, and acquired Sun Microsystems, owner of MySQL, in 2010. Database products licensed as open source are, by the legal terms of the Open Source Definition, free to distribute and free of royalty or other licensing fees.
Pricing

Oracle Corporation offers term licensing for all Oracle products. It bases the list price for a term-license on a specific percentage of the perpetual license price. Prospective purchasers can obtain licenses based either on the number of processors in their target server machines or on the number of potential seats ("named users").[81]

Enterprise Edition
As of July 2010[update], the database that costs the most per machine-processor among Oracle database editions, at $47,500 per processor. The term "per processor" for Enterprise Edition is defined with respect to physical cores and a processor core multiplier (common processors = 0.5*cores). e.g. An 8-processor, 32-core server using Intel Xeon 56XX CPUs would require 16 processor licenses.[82][83]
Standard Edition
Cheaper: it can run on up to four processors but has fewer features than Enterprise Edition—it lacks proper parallelization,[84] etc.; but remains quite suitable for running medium-sized applications.
Standard ONE
Sells even more cheaply, but remains limited to two CPUs. Standard Edition ONE sells on a per-seat basis with a five-user minimum. Oracle Corporation usually sells the licenses with an extra 22% cost for support and upgrades (access to MetaLink—Oracle Corporation's support site) which customers need to renew annually.
Oracle Express Edition (Oracle XE)
An addition to the Oracle database product family (beta version released in 2005, production version released in February 2006), offers a free version of the Oracle RDBMS, but one limited to 4 GB of user data and to 1 GB of RAM (SGA+PGA). XE will use no more than one CPU and lacks an internal JVM. XE runs only on Windows and on Linux, not on AIX, Solaris, HP-UX and the other operating systems available for other editions.

As computers running Oracle often have eight or more processors, the software price can rise into the hundreds of thousands of dollars. The total cost of ownership often exceeds this, as large Oracle installations usually require experienced and trained database administrators to do the set-up properly. Because of the product's large installed base and available training courses, Oracle specialists in some areas have become a more abundant resource than those for more exotic databases. Oracle frequently provides special training offers for database-administrators.

On Linux, Oracle's certified configurations include mostly commercial Linux distributions (Red Hat Enterprise Linux 3, 4 and 5, SuSE SLES 8, 9 and 10, Asianux) which can cost in a range from a few hundred to a few thousand USD per year (depending on processor architecture and the support package purchased).

The Oracle database system can also install and run on freely available Linux distributions such as the Red Hat-based CentOS,[85] or Debian-based systems.[86]
[edit] See also

* Comparison of relational database management systems
* Comparison of object-relational database management systems
* Database management system
* List of ERP software packages
* List of relational database management systems
* Oracle Rdb for OpenVMS
* Run Book Automation.