Adsorption (Activated Carbon)

Compiled by:

Félicien Mazille (Aquasis, cewas international centre for water management services) , Dorothee Spuhler (seecon international gmbh)

Activated carbon filtration is a commonly used technology based on the adsorption of contaminants onto the surface of a filter. This method is effective in removing certain organics (such as unwanted taste and odours, micropollutants), chlorine, fluorine or radon from drinking water or wastewater. However, it is not effective for microbial contaminants, metals, nitrates and other inorganic contaminants. The adsorption efficiency depends on the nature of activated carbon used, the water composition, and operating parameters. There are many types of activated carbon filters that can be designed for household, community and industry requirements. Activated carbon filters are relatively easy to install but require energy and skilled labour and can have high costs due to regular replacement of the filter material.

In	Out
Freshwater,Non-biodegradable Wastewater, Treated Water	Drinking Water, Treated Water

Introduction

The use of carbon in the form of charcoal has been used since antiquity for many applications. In Hindu documents dating from 450 BC charcoal filters are mentioned for the treatment of water. Charred wood, bones and coconut charcoals were used during the 18th and 19th century by the sugar industry for decolourising solutions (CECEN 2011). Activated carbon is a material prepared in such a way that it exhibits a high degree of porosity and an extended surface area.

A typical carbon particle has numerous pores that provide a large surface area for water treatment. Source: LEMLEY et al. (1995)

During water filtration through activated carbon, contaminants adhere to the surface of these carbon granules or become trapped in the small pores of the activated carbon (AMIRAULT et al. 2003). This process is called adsorption. Activated carbon filters are efficient to remove certain organics (such as unwanted taste and odours, micropollutants), chlorine, fluorine or radon, from drinking water or wastewater. However, it is not effective for microbial contaminants, metals, nitrates and other inorganic contaminants.Activated carbon filtration is commonly used in centralised treatment plants and at household level, to produce drinking water and in industries to treat effluents. It is also an upcoming treatment applied for the removal of micropollutants both in drinking water production and for the purification of treated wastewater before disposal (see also surface disposal or surface and subsurface groundwater recharge).

Treatment Principles

(Adapted from LEMLEY et al. 1995)

Activated carbon filters for water treatment. Source: FOCUS TECHNOLOGY CO LTD (2011)

There are two basic types of water filters: particulate filters and adsorptive/reactive filters. Particulate filters exclude particles by size, and adsorptive/reactive filters contain a material (medium) that either adsorbs or reacts with a contaminant in water. The principles of adsorptive activated carbon filtration are the same as those of any other adsorption material. The contaminant is attracted to and held (adsorbed) on the surface of the carbon particles. The characteristics of the carbon material (particle and pore size, surface area, surface chemistry, etc.) influence the efficiency of adsorption.
The characteristics of the chemical contaminant are also important. Compounds that are less water-soluble are more likely to be adsorbed to a solid. A second characteristic is the affinity that a given contaminant has with the carbon surface. This affinity depends on the charge and is higher for molecules possessing less charge. If several compounds are present in the water, strong adsorbers will attach to the carbon in greater quantity than those with weak adsorbing ability.

Preparation of Activated Carbon

(Adapted from DROVAC and SKIPTON 2008)

Wood based powder activated carbon for drinking water treatment. Source: GCHFF (2011)

The medium for an activated carbon filter is typically petroleum coke, bituminous coal, lignite, wood products, coconut shell or peanut shell. The carbon medium is “activated” by subjecting it to stream (a gas like water, argon or nitrogen) and high temperature (800-1000°C) usually without oxygen. In some cases, the carbon may also undergo an acidic wash or be coated with a compound to enhance the removal of specific contaminants. The activation produces carbon with many pores and a high specific surface area. It is then crushed to produce a granular or pulverised carbon product.

Use of Activated Carbon Units

(Adapted from DROVAC and SKIPTON 2008)

 Types of activated carbon units. Source: AMIRAULT et al. (2003)

Activated carbon units are commonly used to remove organics (odours, micropollutants) from drinking water at centralised and decentralised level. At centralised level, they are generally part of one of the last steps, before the water is fed into the water distribution network. At decentralised level, activated carbon filtration units can either be point-of-use (POU) or point-of-entry (POE) treatment. A POE device is recommended for the treatment of radon and volatile organic compounds because these contaminants can easily vaporise from water in showers or washing machines and expose users to health hazards. POU devices are useful for the removal of lead and chlorine. The structure of POU devices can either be in-line, line-bypass faucet mounted (see also advanced filters) or pour-through (similar to the design of ceramic candles, colloidal silver or biosand filters).
Activated carbon filters can also be used as a tertiary treatment in wastewater treatment plants to remove micropollutants from municipal effluents or recalcitrant contaminants from industrial effluents.

Combination of Activated Carbon With Other Processes

Activated carbon is often used as pre-treatment to protect other water treatment units such as reverse osmosis membranes and ion exchange resins from possible damage due to oxidation or organic fouling. The combination of ozonation with activated carbon is a very efficient technique for eliminating organic matter including micropollutants. Besides, the lifetime of activated carbon filters is extended drastically when used in combination with ozone, deceasing operation costs substantially (AEPPLI and DYER-SMITH 1996).

Cost Considerations

(Adapted from AMIRAULT et al. 2003)
Installation costs are moderate but additional technical equipment is required. Operating costs are usually limited to filter replacement. Depending on the type and concentration of the contaminant being removed, some carbon filters may require special hazardous waste handling and disposal, which can be costly.

Operation and Maintenance

(Adapted from LEMLEY et al. 1995)
Carbon filters are relatively easy to install and maintain but skilled labour is required at least occasionally for monitoring the removal performance over time of both POU and POE equipment. Activated carbon filters have a limited lifetime. After long-term use, their surfaces are saturated with adsorbed pollutants and no further purification occurs. The filter material therefore has to be replaced at regular intervals, according to manufacturer's instructions. Replacement intervals should be calculated based on the average daily water use through the filter and the amount of contaminant being removed. Cartridge disposal depends on usage. A carbon cartridge can be backwashed and then reused or discarded if non-toxics have been adsorbed.

At a Glance

Working Principle	The pollutants are removed from water through adsorption on the surface of the activated carbon. Use at the POE or POU (e.g. advanced filters).
Capacity/Adequacy	Simple technique using abundant raw material (e.g. petroleum coke, bituminous coal, lignite, wood products, coconut shell or peanut shell). Skilled labour required at least occasionally.
Performance	Efficient for pollutant having high affinity with activated carbon surface (non-polar compounds).
Costs	Relatively low operation costs.
Self-help Compatibility	Initial analysis of water is required to choose proper adsorbent (type of activated carbon).
O&M	Regular replacement or regeneration of carbon cartridge.
Reliability	Reliable if the water composition is taken into account when choosing the type of activated carbon used as filter material.
Main strength	Activated carbon can be produced relatively easily everywhere in the world.
Main weakness	Filter has to be replaced on a regular basis.

Applicability

Activated carbon filters are widely used to produce drinking water at household and community level (to remove certain organics, chlorine or radon from drinking water) and to treat industrial or municipal wastewaters. It is not efficient for disinfection and nitrates removal. Adsorption on activated carbon is a simple technology based on materials such as fossil fuels (petroleum coke, lignite...) and even agricultural waste (e.g. coconut shell, wood, etc.).
To choose the most applicable type of activated carbon for a given application it is important to analyse the composition of the influent water previously. The carbon filter has to be replaced or regenerated regularly to remain efficient. Activated carbon can also be used as a pre-treatment to protect other water treatment units.

Advantages

• Easy to install and maintain
• Can be used at the point-of-entry (semi-centralised drinking water treatment plants, wastewater treatment plants) or at the point-of-use (household/community filters)
• Efficient to remove certain organics, chlorine, radon
• Based on materials available everywhere

Disadvantages

• Filter has to be replaced regularly
• Skilled labour required, at least occasionally
• Water analysis is required to choose the most adapted type of activated carbon
• Contaminants are separated from water but not destroyed

References

AEPPLI, J.; DYER-SMITH, P. (1996): Ozonation and Granular Activated Carbon Filtration the Solution to Many Problems. In: Proceedings of the First Australian Conference of the International Ozone Association. URL [Accessed: 04.10.2011].

AMIRAULT, R.; CHOBANIAN, G.; MCCANTS, D.; MCCANN, A.; BURDETT, H.; NEPTIN,B. (2003): Activated Carbon Treatment of Drinking Water Supplies. In: Healthy Drinking Waters for Rhode Islanders. URL [Accessed: 04.10.2011]. PDF

CECEN, F. (2011): Water and Wastewater Treatment: Historical Perspective of Activated Carbon Adsorption and its Integration with Biological Processes. In: WILEY-VCH Verlag GmbH & Co. KGaA. URL [Accessed: 04.10.2011].

DROVAC, B. I.; SKIPTON, S.O. (2008): Drinking Water treatment: Activated Carbon. In: University of Nebraska-Lincoln Extension . URL [Accessed: 04.10.2011].

FOCUS TECHNOLOGY CO LTD (Editor) (2011): Water Treatment System (Active Carbon Filter). Zhangjiagang Beyond Machinery Co. Ltd.. URL [Accessed: 10.11.2011].

GCHFF (Editor) (2011): Wood based Powder Activated Carbon. Henan: Gongyi City Hongda Filter Factory (GCHFF) . URL [Accessed: 10.11.2011].

LEMLEY, A.; WAGENET, L.; KNEEN, B. (1995): Activated Carbon Treatment of Drinking Water. In: Water Treatment Notes Cornell Cooperative Extension. URL [Accessed: 04.10.2011]. PDF

For further readings, case studies, awareness raising material, training material, important weblinks or the related powerpoint presentation, see www.sswm.info/taxonomy/term/

'Dyson sphere' star found to be dimming dramatically - and nobody knows why

Alien megastructure mystery deepens: 'Dyson sphere' star found to be dimming dramatically - and nobody knows why

This star is breaking all the rules.

Bizarre readings from star called KIC 8462852 have baffled scientists

One theory is dips in light caused by structure similar to Dyson sphere

Others suggest break up of huge comets would block the starlight

A Kickstarter campaign to investigate has reached its £68,352 target

The star KIC 8463853 has a dark secret. Literally. In 2011 and 2013, the light from this star plummeted by as much as 20 percent, suggesting that something very big must be blocking the light. Like, something 20 times the size of Jupiter. Scientists have speculated that comets, gobs of dust, or even a large alien structure could be causing the dimming, but so far, none of the explanations really works.

Now, a paper that was just published to the arxiv has found that the star dimmed by an unprecedented amount over the whole four years that the Kepler telescope kept an eye on it. It's not known whether this phenomenon is connected to the huge but short-duration dips from 2011 and 2013.

Big Dipper

In new study, which is not yet peer-reviewed, astronomers Ben Montet and Joshua Simon measured the light from the star (known informally as "Tabby's Star") that the Kepler telescope recorded during its four-year mission. And they found some pretty strange activity.

For the first few years, Tabby's Star dimmed at about 0.34 percent per year. Then its light level dropped dramatically by about 2.5 percent in 200 days. After that it returned to the original slow fade rate.

The authors looked at 500 other stars in the vicinity of Tabby's Star, as well as 500 other stars that are similar in size and makeup to Tabby's Star, but none of the others experienced such a dramatic drop in light levels. Their brightness remained essentially unchanged.

A Long-Term Trend?

Previously, old astronomy plates indicated the star has been dimming for the past century, which would require a seemingly impossible number of giant comets to explain the trend. However, scientists disagree over those findings, and the debate over long-term dimming remains inconclusive.

The Kepler telescope's high precision data show that the star was definitely dimming over the 4 years that Kepler monitored this star, suggesting that the long-term dimming hypothesis is possible, but scientists still can't say for sure.

"These results introduce us to another delightfully unexpected piece of the puzzle," says Tabetha Boyajian, one of the star's discoverers and the namesake of the Tabby's Star nickname.

"Tabby's star continues to defy easy explanation!" Keivan Stassun, who has studied the star's long-term light patterns, told Popular Science in an email. "These intriguing new findings suggest that none of the considered phenomena can alone explain the observations. Of course, the star doesn't have to abide by our hope for a single explanation. In the end, figuring out this puzzle may require accounting for a combination of effects."

Defying Explanation

Scientists differ in their favorite explanations for what's happening around Tabby's Star. While Boyajian still thinks the most likely explanation is a group of cold comets, Montet thinks the evidence is growing that a large cloud of dust is blocking the star's light.

"Tabby's star continues to defy easy explanation."

If the light were being blocked by comet or dust (or an alien Dyson swarm, for that matter), scientists would expect to see extra heat energy coming from around the star. So far they don't, but Montet wonders if taking deeper measurements will find the missing energy.
"There's a lot of explanations that explain half or two-thirds of story, but there's nothing that fully explains everything," he says.
Although many uncertainties remain, the possibility that the weird blips in light are being caused by some previously undiscovered star behavior is at least seeming less likely, according to Montet.

"To have one thing that we haven't seen before might be explainable with a stellar mechanism, but this is a few things now. It seems unlikely we would miss a stellar mechanism that fits all of these."

Finding An Answer

To find out what's causing KIC 8462852's mysterious behavior, scientists want to study it while it's in the midst of one of the major dips, like the ones that happened in 2011 and 2013.
Although the Kepler telescope is no longer able to keep an eye on Tabby's Star, Boyajian's team recently won funding to continue monitoring the star using the Las Cumbres Observatory Global Telescope Network (LCOGT). If any funny business is detected, networks of astronomers--both professional and amateur--will be contacted immediately in order to collect as much data about the dimming event as possible.

Observations from the ground, like those of the LCOGT, aren't as precise as those of a space telescope like Kepler, but an upcoming telescope from the European Space Agency could also lend a hand.
PLATO (PLAnetary Transits and Oscillations of stars) will be like "Kepler on steroids," says Montet. The space-based telescope is expected to spend a few years studying the same region that Kepler monitored. The telescope is expected to launch in 2024.

In the meantime, the mystery surrounding Tabby's Star only deepens.

https://arxiv.org/abs/1608.01316

http://www.popsci.com/have-we-detected-alien-megastructures…

http://www.popsci.com/something-made-alien-megastructure-st…

http://www.popsci.com/study-confirms-that-alien-megastructu…

Cecile G. Tamura

Artist illustration of a crumbling Dyson sphere

Danielle Futselaar/SETI International

What is a Dyson Sphere ?

A proposed method for harnessing the power of an entire star is known as a Dyson sphere.

First proposed by theoretical physicist Freeman Dyson in 1960, this would be a swarm of satellites that surrounds a star.

They could be an enclosed shell, or spacecraft spread out to gather its energy - known as a Dyson swarm.

If such structures do exist, they would emit huge amounts of noticeable infrared radiation back on Earth.

But as of yet, such a structure has not been detected.

Source: All About Space magazine

Interest in the star, which is 1,480 light-years away, began last October when Yale scientists found unusual fluctuations in its light - with some suggesting the dips in light are caused by an alien megastructure. One theory that has got traction says the dips are caused by an alien megastructure, similar to a Dyson sphere (stock image)

Credit : Jay Wong/ All About Space Magazine

KIC 8462852, located 1,480 light-years away, was monitored by the Kepler Space Telescope for more than four years, beginning in 2009.

As a planet passes in front of a star's light it causes the light to dim, and Kepler can capture these fluctuations.

Typically this light dims in a symmetrical pattern.

However, during Kepler's study into KIC 8462852 the researchers noticed it went through 'irregularly shaped, aperiodic dips.'

In some cases, the flux dropped down to below the 20% level and lasted between 5 and 80 days at a time.

Some stars don't have uniformly bright discs and spin at such a high rate that they have an spheroidal shape.

This causes them to have a larger radius at the equator than at the poles.

The poles, with their smaller radius, have a higher surface gravity meaning they are hotter and brighter - or 'gravity brightened.'

Meanwhile, the equator is cooler and darker, which is known being 'gravity darkened.'

Mr Galasyn suggests that the dips and increases in flux of KIC 8462852 are caused as planets move across these brighter and darker areas.

Two of the dips, on day 1520 and 1570 of Kepler's mission, are shown having a similar shape but a different magnitude.

Despite their differences, both curves follow the shape of a planet travelling across a brightened pole, as suggested by the paper.

Mr Glasnyn claims that the two dips could be caused by two planets moving in front of the star.

If the first planet is large it could block out around 20% of the star's disc, while a smaller planet could occlude just 8% of it.

The second dip may be shorter because the smaller planet is moving faster and orbiting closer to the star.

Astronomers have been looking for answers about what is causing the bizarre light fluctuations around the star KIC 8462852 (pictured) for weeks. Some have suggested it is an alien megastructure such as a Dyson sphere. The strange structure was spotted by researchers from Yale

Dredit : Arxiv

Ruling out an alien structure

In order to explore the idea that such a structure could have been built by intelligent alien life, the Extraterrestrial Intelligence Institute, Seti, trained its Allen Telescope Array on the star for more than two weeks.

Experts looked for two types of radio signal: narrow-band signals generated as a 'hailing signal' for alien societies wanting to announce their presence, and broad-band signals.

These signals would be produced by 'beamed propulsion'.

Seti said that if large scale alien engineering projects really are underway, the array would pick up signals made by intense microwave beams that could be used to power spacecraft.

Scientists analysing the data found no clear evidence for either type of signal.

They believe this rules out the presence of omnidirectional transmitters - large antenna - of approximately 100 times today's total terrestrial energy usage in the case of the narrow-band signals, and ten million times that usage for broad band emissions.
So the presence of a Dyson sphere is unlikely.

Anbu manam kanintha pinne

Text messaging may Change How Our Brain Works

Recently, it has been reported that theta brain waves may also be present during text messaging. But it’s not just random theta brain waves – it’s a specific pattern of brain waves that falls within the frequency interval of theta brain waves. And apparently, it only occurs during text messaging, since it hasn’t been found during any other type of activities associated with speech, motor performance, concentration-attention, memory, and cognitive performance. This brain activity pattern has been named “the texting rhythm” and it seems to be a new technology-specific theta wave rhythm that occurs during texting.

Text messaging is a state of alertness that requires a concentrated form of enhanced mental activation associated with speech, visual perception, and specific fine motor skills. Furthermore, the smaller screen size of a smartphone may require a particularly high level of attention while sending a text message. It’s a very specific type of activity, which may account for its distinct brain wave pattern.

Fireman's bicycle from 1905

History of Fire Service Bicycles

The history of fire service bicycles is relatively hazy. I did however, find a handful of useful resources about early fire service vehicles, which appear to have been primarily used prior to the development of motorized transportation. Although I was haven’t yet be able to get my hands on what appears to be a very useful article by Steven Carter (1999) titled Fire Service Bicycles: Did They Ever Exist?, which was published in The Wheelman magazines, I did read through a journal article that cited Carter’s piece. The citing article – The Product Life Cycle and the Use of Bicycles to Deliver Goods and Services by Ross D. Petty – is a definitely worth the read in general. As for its reference to fire service bicycles, Petty indicates that fire service bicycles of some variety were definitely used in Australia, Great Britain, and France, and for the most part, it would appear that the use was limited to the late 1800’s and very early 1900’s.

In 1905, the Birmingham Small Arms (BSA) Company – who are actually well-known for their motorcycles – commissioned a fire service bicycle. It is probably that the use of those fire service bicycles was limited to Great Britain, and I do not know how many were produced. Nonetheless, the frames were designed to accommodate a fire hose, a siren, and an axe.

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இணங்கிப் போதல் ....

அவர்களின்
விருப்பின்படியே
நில்லுங்கள்.

அவர்களின்
விருப்பின்படியே
உட்காருங்கள்.
அவர்களின்
விருப்பின்படியே
உண்ணுங்கள்.
அவர்களின்
விருப்பின்படியே
உடுத்திக் கொள்ளுங்கள்.
அவர்களின்
விருப்பின்படியே
அழுங்கள்,
சிரியுங்கள்,
பேசுங்கள்,
கல்லுங்கள்,
உறங்குங்கள் ,
கனவு காணுங்கள்,
கொட்டாவி விடுங்கள்...
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அவர்களுக்காகவே
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விலா எலும்பிலிருந்து
சிருஸ்டிக்கபட்டவர்கள்.
அவர்களின்
கட்டளைகளுக்கு
கட்டுப்பட வேண்டியவர்கள் .....
இயன்ற அளவுக்கு
அவர்களை
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அவர்கள்
உங்களை
பார்த்த
அடுத்த நொடியே
அவர்கள் மீது
காதல் கொள்ளுங்கள்.
அவர்கள்
தீர்மானிக்கும் காலத்தில்
அவர்களை
திருமணம் செய்யுங்கள்.
அவர்கள்
அழைக்கும் வேளைகளில்
எல்லாம்
அவர்களை
புணர்ந்து கொள்ளுங்கள்.
அவர்கள்
விரும்பும்போது
மட்டுமே
கருத்தரித்து கொள்ளுங்கள்.
இங்கு
உங்களுடைது
என்று
எதுவுமேயில்லை.
நீங்கள்
சும்மா இருப்பதற்கு கூட
அவர்கள்தான்
சுதந்திரம்
அளிக்க வேண்டியிருக்கிறது.
அவர்களின்
அனுமதியின்றி
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அழக்கூட
முடியாதே
இவற்றையெல்லாம்
மனதார ஏற்று
உத்தமியாக,
ஒழுக்க சீலியாக,
பத்தினியாக,
பதிவிரதையாக,
கற்புடையோளாக
வாழ்வதெனில்
மட்டும்
வாழுங்கள்.
அன்றேல்
செத்துப் போங்கள்....
அரிவாள்கள்
ஆயத்தமாகவே
உள்ளன .....

நவாதரன் கவிதைகள்

How Water Jet cutting Works.

There are two main steps involved in the waterjet cutting process. The Electric Servo Pump generally pressurizes normal tap water at pressure levels above 50,000 psi; to produce the energy required for cutting. Water is then focused through a small precious stone orifice to form an intense cutting stream.

 In the 1950s, forestry engineer Dr. Norman Franz experimented with an early form of water jet cutter to cut lumber. However, the technology didn't advance notably until the 1970s. Today the water jet is unparalleled in many aspects of cutting and has changed the way many products are manufactured. Many types of water jets exist today, including plain water jets, abrasive water jets, percussive water jets, cavitation jets and hybrid jets.

The key to cutting metal with water is to keep the spray coherent. Waterjets are able to cut because the spray is channeled through a very narrow jeweled nozzle at a very high pressure to keep the spray coherent. Unlike metal cutters, a waterjet never gets dull and it cannot overheat.

Low pressure waterjets were first used for mining gold in California in 1852. Steam and hot water jets were used in the early 1900s for cleaning. High pressure waterjets were used for mining in the 1960s, and about 10 years ago industry began using waterjets for cutting. Abrasive water jets (abrasivejets) were first used in industry in about 1980.

In the past, only one piece of metal could be cut at a time with a saw or other metal cutting mechanical process. It was time intensive and expensive. Computer-controlled waterjet and abrasivejet cutting are used today in industry to cut many soft and hard materials. The plain water-abrasive mixture leaves the nozzle at more than 900 mph. The latest machines can cut to within two thousandths of an inch, and have jet speeds around Mach 3.

Waterjets can cut:

• Marble
• Granite
• Stone
• Metal
• Plastic
• Wood
• Stainless steel
  

A water jet can cut a "sandwich" of different materials up to four inches thick. This odorless, dust-free and relatively heat-free process can also cut something as thin as five thousandths of an inch. The tiny jet stream permits the first cut to also be the final finished surface. This single cutting process saves material costs and machining costs. For example, the engineer merely gives a gear drawing to the cutting shop via a diskette or e-mail and gets the finished gear back.

Advantages & Disadvantages of Five Generations of Computer

Table of Contents

1.First Generation of Computers (1942-1955)
1.1.Advantages
1.2.Disadvantages

2.Second Generation Computers (1955-1964)
2.1.Advantages
2.2.Disadvantages

3.Third Generation Computers (1964-1975)
3.1.Advantages
3.2.Disadvantages

4.Fourth Generation Computers (1975-Present)
4.1.Advantages
4.2.Disadvantages

5.Fifth Generation Computers (Present And Still Continue)

We Can Divide These electronic Computer in Generations. We can Divide them in Five Generation according to technology used in them. The Five Generation of Computer are As Follows:

The First Generation of Computer (From 1942 - 1955)

We can say that the Start or the beginning of commercial computer age is from UNIVAC (Universal Automatic Computer). This Computer was developed by two scientists Mauchly and Echert at the Census Department of United States in 1947. In the duration of 1942-1955 the first generation computers were used. These Computer were based on vacuum tubes. Examples of first generation computers are ENIVAC and UNIVAC-1.

1.1 Advantages

In those Days Vacuum tubes were the only electronic component available.

These were Vacuum tubes technology that made possible to make electronic digital computers in those days.

These computers were that fast that could calculate data in millisecond.

1.1 Disadvantages

These computers were very large in size.

They were consuming a large amount of energy.

They became heated very soon due to of thousands of vacuum tubes.

These were not very reliable.

To make them rest in cool Air conditioning was required.

For Working for long time Constant maintenance was required.

They were Non-portable.

Very Costly commercial production.

They Limited commercial use.

Very slow speed.

Programming capabilities were Limited .

Machine language was Used only.

Magnetic drums were used which provide very less data storage.

Punch Card were used for input.

They were Not versatile and very faulty.

The Second Generation of Computer (1955 - 1964)

In second generation of computers Transistor were used. The scientists developed transistor in 1947 at Bell laboratories. These are the scientists include John Barden, William Brattain and William Shockley. By replacing vacuum tubes with transistors the size of the computers was decreased. This is the examples of second generation computers that are IBM 7094 series, IBM 1400 series and CDC 164 etc.

2.2 Advantages

This was Smaller in size as compared to the first generation computers.

The 2nd generation Computers were more reliable then First Generation of Computer.

They were Using less energy and were not heated.

Widely used for commercial.

They were Better portable as compared to the first generation computers.

They were Better in speed and could calculate data in microseconds

They were Using faster peripherals like tape drives, magnetic disks, printer etc.

The Assembly language was used instead of Machine language.

The Accuracy was improved.

2.2 Disadvantages

These also need Cooling system.

The Constant maintenance was also required

The Commercial production was difficult

These were used only for specific purposes

They were very Costly and not versatile

As same as Punch cards were used for input.

The Third Generation of Computers (1964 - 1975)

The  integrated circuits (IC) was used in Developing the Third generation computers. In 1958 Jack Kilby developed the concept of integrated circuit . It was an important invention in the computer field at that Time. The first IC was invented and used in 1961. The size of an IC is about ¼ square inch. There A single IC chip may contain thousands of transistors. These computer became smaller in size, faster, more reliable and less expensive. These are the examples of third generation computers which are IBM 370, IBM System/360, UNIVAC 1108 and UNIVAC AC 9000 etc.

3.3 Advantages

This was very Smaller in size as compared to previous generations.

And it was More reliable.

They Used less energy

They Produced less heat as compared to the previous two GOC (Generation of Computer).

They were Better in speed and could calculate data in nanoseconds.

They were Using fan for heat discharge to prevent damage.

The Maintenance cost was low because hardware failure is reare.

They were Totally general purpose

They Could be used for high-level languages.

Have a Good storage

Versatile to an extent

They were Less expensive

Have a Better accuracy

The Commercial production increased.

They were Using mouse and keyboard for input.

3.3 Disadvantages

The Air conditioning was required.

There is a Highly sophisticated technology required for the manufacturing of IC chips.

The Fourth Generation of Computers (1975 and Still Continue)

It was fourth generation of computers that started with the invention of Microprocessor. The Microprocessor contains thousands of ICs. In 1971 Ted Hoff produced the first microprocessor for Intel. It was known as Intel 4004. The technology of integrated circuits was improved rapidly. The LSI (Large Scale Integration) circuit and VLSI (Very Large Scale Integration) circuit was designed. It greatly reduced the size of computer. The size of modern Microprocessors is usually one square inch. It can have millions of electronic circuits. The examples of fourth generation computers are Apple Macintosh & IBM PC.

4.4 Advantages

These are More powerful and reliable than previous generations.

Very Small in size According to Previous Generations

They have Fast processing power with less power consumption

They use Fan for heat discharging and thus to keep them cold.

They required No air conditioning.

They were Totally general purpose

Commercial production

Less repairing is needed.

These are Cheapest among all generations

All types of High level languages can be used in this type of computers.

4.4 Disadvantages

The latest technology is required for manufacturing of Microprocessors.

Fifth Generation Computers (Present & Beyond)

The Scientists are working hard and Trying there best on the 5th generation computers with quite a few breakthroughs. It is based on the technique of Artificial Intelligence (AI). Computers can understand spoken words & imitate human reasoning. It Can respond itself to its surroundings using different types of sensors. The Scientists are constantly working to increase the processing power of computers. They are trying to create a computer with real IQ with the help of advanced programming and technologies.The are trying to make computer That very reliable as Human Understanding. IBM Watson computer's one example that outsmarts Harvard University Students. The advancement in modern technologies will revolutionize the computer in future. This will be the Fifth Generation of Computers.

Thanks  http://provalley.blogspot.com

The Dogmatic Physicalism of Pope Sean Carroll

RE: The Big Picture
Don’t be Fooled by THE BIG TALK. This book is a piece if 21st century closed minded dogmatic physicalism. Here’s the dogma: Physics has a theory called “the Core Theory.” It holds that everything is particle based. The Big Bang produced the particles, and we are all riding through time on the momentum of that “initial condition of the universe.” You are free to talk about having an immaterial mind, or consciousness, but you are Wrong. Every little thing is, and can only be, a collection of particles. The author can’t explain how that works, but he insists (in the book and to his audiences) that any story about consciousness, or self-awareness as immaterial is wrongheaded. Only stories that are compatible with The Core Theory of physics can be true, or anywhere near true.

This dogmatic doctrine raises at least two questions the book and author avoid, because they can’t answer them. One is, what makes the story told by physics – the Core Theory (that all is particles) – any more true than non-particle based stories? If you feel and experience that your self-awareness is something other than a bunch of tiny pieces of matter in your head, then you must be delusional, because only the story told by physics can be true.
Second, how is the theory that the “initial condition of the universe” causes and constitutes all, any different than God caused and created all? In short, this book is a parallel universe to Religion! The Core Theory dogma has no proof that your mind is a self-delusion, nor that something exists outside the puny minded demands that nothing can possibly exist unless it’s a collection of particles, held together by gravity, and set in motion by the Big Bang.
The Catholic Church claims Omniscience, and John Carroll wants to put Particle Physics in its place, with himself as the New Pope. Skeptics Beware! Contrary to its promises, this book will tell you nothing about “life,” and try to sell you on the idiotic claim that “meaning” is a bunch of particles swimming around in your brain. Carrol asks for your Faith. I wouldn’t give him that or my money!
William J. Kelleher, Ph.D.
Author of The Human Birth Defect