Monday, 5 July 2021

Best 61 Social Bookmarking List in 2021 for Search Engine Optimization.

Sl No Social Bookmarking Sites                            DA    PA

1        https://www.google.com/bookmarks                100  80

5        https://in.linkedin.com/                                     99      85

2        https://medium.com                                           96        81

3        https://www.pinterest.com                                 94      96

4        https://twitter.com                                               94         100

6        https://bitly.com                                                  93      75

7        https://www.scoop.it                                           92   74

8        https://www.evernote.com                                92     75

9        https://www.reddit.com                                    91      90

10      https://trello.com                                             91      76

11      https://slashdot.org/                                         91      75

12      https://slack.com/intl/en-in/                           91     39

13      https://getpocket.com                                      91       75

14      https://lastpass.com                                         90        70

15      https://flipboard.com                                        90      70

16      https://www.soup.io                                          89       95

17      https://www.diigo.com                                89       74

18      https://steemit.com/                                    89       67

19      https://www.plurk.com                                88       70

20      https://www.pearltrees.com                           88     70

21      https://linktr.ee/                                         88        66

22      https://www.instapaper.com                          87     70

23      https://www.metafilter.com/                          86     65

24      https://www.tumblr.com                             85       100

25      https://feedly.com/                                     85        75

26      https://list.ly                                                      83 64

27      https://dzone.com/                                     83        63

28      https://padlet.com                                      82        71

29      https://www.techdirt.com/                             80     64

30      https://www.tagged.com/                     80     64

31      https://www.intensedebate.com             79    64

32      https://mix.com                                         79        61

33      https://lockerdome.com                               79       57

34      https://www.mindmeister.com              78    66

35      https://weheartit.com                                  77       95

36      https://www.fark.com                                  76       67

37      https://itsmyurls.com                                  76       57

38      https://contently.com                                  76       62

39      https://miro.com/                                         74      57

40      https://newsblur.com/                                  73       57

41      https://www.mendeley.com                           70     66

42      https://www.symbaloo.com/                          69     63

43      http://www.blogengage.com/                         69     54

44      https://www.wakelet.com                                           66  58

45      https://www.easypolls.net                                                64     55

46      https://bubbl.us                                           64      64

47      http://www.folkd.com/                                62       67

48      https://coggle.it                                         61        59

49      https://www.protopage.com                      59 58

50      https://www.dropmark.com                      59 54

51      https://start.me                                          59        52

52      https://www.livebinders.com/                  58  59

53      https://www.allmyfaves.com                     58         58

54      http://www.spoke.com/                                 58      58

55      http://www.livebinders.com/                 58    59

56      https://thebrain.com                           57      48

57      https://app.thebrain.com/                    57      38

58      http://www.ttlink.com/                       57      59

59      https://www.storeboard.com/               56      61

60      https://www.mind42.com                     56      56

61      https://share.bizsugar.com/                  55      48

Source: https://www.seoaimpoint.com/                   


Friday, 2 July 2021

Biography of Father of Computer and His Thought on Religion.

 Charles Babbage 26 December 1791 – 18 October 1871

Charles Babbage was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer.

Babbage is considered by some to be "father of the computer".Babbage is credited with inventing the first mechanical computer, the Difference Engine, that eventually led to more complex electronic designs, though all the essential ideas of modern computers are to be found in Babbage's Analytical Engine. His varied work in other fields has led him to be described as "pre-eminent" among the many polymaths of his century.

Babbage, who died before the complete successful engineering of many of his designs, including his Difference Engine and Analytical Engine, remained a prominent figure in the ideating of computing. Parts of Babbage's incomplete mechanisms are on display in the Science Museum in London. In 1991, a functioning difference engine was constructed from Babbage's original plans. Built to tolerances achievable in the 19th century, the success of the finished engine indicated that Babbage's machine would have worked.

Early Life:

Babbage's birthplace is disputed, but according to the Oxford Dictionary of National Biography he was most likely born at 44 Crosby Row, Walworth Road, London, England. A blue plaque on the junction of Larcom Street and Walworth Road commemorates the event.

 His date of birth was given in his obituary in The Times as 26 December 1792; but then a nephew wrote to say that Babbage was born one year earlier, in 1791. The parish register of St. Mary's, Newington, London, shows that Babbage was baptised on 6 January 1792, supporting a birth year of 1791.

Babbage c. 1850

Babbage was one of four children of Benjamin Babbage and Betsy Plumleigh Teape. His father was a banking partner of William Praed in founding Praed's & Co. of Fleet Street, London, in 1801. In 1808, the Babbage family moved into the old Rowdens house in East Teignmouth. Around the age of eight, Babbage was sent to a country school in Alphington near Exeter to recover from a life-threatening fever. For a short time he attended King Edward VI Grammar School in Totnes, South Devon, but his health forced him back to private tutors for a time.

 

Babbage then joined the 30-student Holmwood Academy, in Baker Street, Enfield, Middlesex, under the Reverend Stephen Freeman. The academy had a library that prompted Babbage's love of mathematics. He studied with two more private tutors after leaving the academy. The first was a clergyman near Cambridge; through him Babbage encountered Charles Simeon and his evangelical followers, but the tuition was not what he needed. He was brought home, to study at the Totnes school: this was at age 16 or 17. The second was an Oxford tutor, under whom Babbage reached a level in Classics sufficient to be accepted by Cambridge.


At the University of Cambridge

Babbage arrived at Trinity College, Cambridge, in October 1810 He was already self-taught in some parts of contemporary mathematics; he had read in Robert Woodhouse, Joseph Louis Lagrange, and Marie Agnesi. As a result, he was disappointed in the standard mathematical instruction available at the university.

Babbage, John Herschel, George Peacock, and several other friends formed the Analytical Society in 1812; they were also close to Edward Ryan. As a student, Babbage was also a member of other societies such as The Ghost Club, concerned with investigating supernatural phenomena, and the Extractors Club, dedicated to liberating its members from the madhouse, should any be committed to one.

In 1812, Babbage transferred to Peterhouse, Cambridge. He was the top mathematician there, but did not graduate with honours. He instead received a degree without examination in 1814. He had defended a thesis that was considered blasphemous in the preliminary public disputation; but it is not known whether this fact is related to his not sitting the examination.

After Cambridge

Considering his reputation, Babbage quickly made progress. He lectured to the Royal Institution on astronomy in 1815, and was elected a Fellow of the Royal Society in 1816. After graduation, on the other hand, he applied for positions unsuccessfully, and had little in the way of career. In 1816 he was a candidate for a teaching job at Haileybury College; he had recommendations from James Ivory and John Playfair, but lost out to Henry Walter. In 1819, Babbage and Herschel visited Paris and the Society of Arcueil, meeting leading French mathematicians and physicists. That year Babbage applied to be professor at the University of Edinburgh, with the recommendation of Pierre Simon Laplace; the post went to William Wallace.

With Herschel, Babbage worked on the electrodynamics of Arago's rotations, publishing in 1825. Their explanations were only transitional, being picked up and broadened by Michael Faraday. The phenomena are now part of the theory of eddy currents, and Babbage and Herschel missed some of the clues to unification of electromagnetic theory, staying close to Ampère's force law.

Babbage purchased the actuarial tables of George Barrett, who died in 1821 leaving unpublished work, and surveyed the field in 1826 in Comparative View of the Various Institutions for the Assurance of Lives. This interest followed a project to set up an insurance company, prompted by Francis Baily and mooted in 1824, but not carried out. Babbage did calculate actuarial tables for that scheme, using Equitable Society mortality data from 1762 onwards.

During this whole period Babbage depended awkwardly on his father's support, given his father's attitude to his early marriage, of 1814: he and Edward Ryan wedded the Whitmore sisters. He made a home in Marylebone in London, and founded a large family. On his father's death in 1827, Babbage inherited a large estate (value around £100,000, equivalent to £8.72 million or $11.1 million today), making him independently wealthy. After his wife's death in the same year he spent time travelling. In Italy he met Leopold II, Grand Duke of Tuscany, foreshadowing a later visit to Piedmont. In April 1828 he was in Rome, and relying on Herschel to manage the difference engine project, when he heard that he had become professor at Cambridge, a position he had three times failed to obtain (in 1820, 1823 and 1826).

Royal Astronomical Society

Babbage was instrumental in founding the Royal Astronomical Society in 1820, initially known as the Astronomical Society of London. Its original aims were to reduce astronomical calculations to a more standard form, and to circulate data. These directions were closely connected with Babbage's ideas on computation, and in 1824 he won its Gold Medal, cited "for his invention of an engine for calculating mathematical and astronomical tables".

Babbage's motivation to overcome errors in tables by mechanisation had been a commonplace since Dionysius Lardner wrote about it in 1834 in the Edinburgh Review (under Babbage's guidance). The context of these developments is still debated. Babbage's own account of the origin of the difference engine begins with the Astronomical Society's wish to improve The Nautical Almanac. Babbage and Herschel were asked to oversee a trial project, to recalculate some part of those tables. With the results to hand, discrepancies were found. This was in 1821 or 1822, and was the occasion on which Babbage formulated his idea for mechanical computation. The issue of the Nautical Almanac is now described as a legacy of a polarisation in British science caused by attitudes to Sir Joseph Banks, who had died in 1820.

Babbage studied the requirements to establish a modern postal system, with his friend Thomas Frederick Colby, concluding there should be a uniform rate that was put into effect with the introduction of the Uniform Fourpenny Post supplanted by the Uniform Penny Post in 1839 and 1840. Colby was another of the founding group of the Society. He was also in charge of the Survey of Ireland. Herschel and Babbage were present at a celebrated operation of that survey, the remeasuring of the Lough Foyle baseline.

British Lagrangian School

The Analytical Society had initially been no more than an undergraduate provocation. During this period it had some more substantial achievements. In 1816 Babbage, Herschel and Peacock published a translation from French of the lectures of Sylvestre Lacroix, which was then the state-of-the-art calculus textbook.

Reference to Lagrange in calculus terms marks out the application of what are now called formal power series. British mathematicians had used them from about 1730 to 1760. As re-introduced, they were not simply applied as notations in differential calculus. They opened up the fields of functional equations (including the difference equations fundamental to the difference engine) and operator (D-module) methods for differential equations. The analogy of difference and differential equations was notationally changing Δ to D, as a "finite" difference becomes "infinitesimal". These symbolic directions became popular, as operational calculus, and pushed to the point of diminishing returns. The Cauchy concept of limit was kept at bay. Woodhouse had already founded this second "British Lagrangian School" with its treatment of Taylor series as formal.

In this context function composition is complicated to express, because the chain rule is not simply applied to second and higher derivatives. This matter was known to Woodhouse by 1803, who took from Louis François Antoine Arbogast what is now called Faà di Bruno's formula. In essence it was known to Abraham De Moivre (1697). Herschel found the method impressive, Babbage knew of it, and it was later noted by Ada Lovelace as compatible with the analytical engine.[45] In the period to 1820 Babbage worked intensively on functional equations in general, and resisted both conventional finite differences and Arbogast's approach (in which Δ and D were related by the simple additive case of the exponential map). But via Herschel he was influenced by Arbogast's ideas in the matter of iteration, i.e. composing a function with itself, possibly many times. Writing in a major paper on functional equations in the Philosophical Transactions (1815/6), Babbage said his starting point was work of Gaspard Monge.

Academic

From 1828 to 1839, Babbage was Lucasian Professor of Mathematics at Cambridge. Not a conventional resident don, and inattentive to his teaching responsibilities, he wrote three topical books during this period of his life. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1832. Babbage was out of sympathy with colleagues: George Biddell Airy, his predecessor as Lucasian Professor of Mathematics at Trinity College, Cambridge, thought an issue should be made of his lack of interest in lecturing. Babbage planned to lecture in 1831 on political economy. Babbage's reforming direction looked to see university education more inclusive, universities doing more for research, a broader syllabus and more interest in applications; but William Whewell found the programme unacceptable. A controversy Babbage had with Richard Jones lasted for six years. He never did give a lecture.

It was during this period that Babbage tried to enter politics. Simon Schaffer writes that his views of the 1830s included disestablishment of the Church of England, a broader political franchise, and inclusion of manufacturers as stakeholders. He twice stood for Parliament as a candidate for the borough of Finsbury. In 1832 he came in third among five candidates, missing out by some 500 votes in the two-member constituency when two other reformist candidates, Thomas Wakley and Christopher Temple, split the vote. In his memoirs Babbage related how this election brought him the friendship of Samuel Rogers: his brother Henry Rogers wished to support Babbage again, but died within days. In 1834 Babbage finished last among four. In 1832, Babbage, Herschel and Ivory were appointed Knights of the Royal Guelphic Order, however they were not subsequently made knights bachelor to entitle them to the prefix Sir, which often came with appointments to that foreign order.

"Babbage principle"

In Economy of Machinery was described what is now called the "Babbage principle". It pointed out commercial advantages available with more careful division of labour. As Babbage himself noted, it had already appeared in the work of Melchiorre Gioia in 1815. The term was introduced in 1974 by Harry Braverman. Related formulations are the "principle of multiples" of Philip Sargant Florence, and the "balance of processes".

What Babbage remarked is that skilled workers typically spend parts of their time performing tasks that are below their skill level. If the labour process can be divided among several workers, labour costs may be cut by assigning only high-skill tasks to high-cost workers, restricting other tasks to lower-paid workers.[78] He also pointed out that training or apprenticeship can be taken as fixed costs; but that returns to scale are available by his approach of standardisation of tasks, therefore again favouring the factory system. His view of human capital was restricted to minimising the time period for recovery of training costs.



Difference engine

The Science Museum's Difference Engine No. 2, built from Babbage's design

Portion of Babbage's difference engine.

Babbage began in 1822 with what he called the difference engine, made to compute values of polynomial functions. It was created to calculate a series of values automatically. By using the method of finite differences, it was possible to avoid the need for multiplication and division.

For a prototype difference engine, Babbage brought in Joseph Clement to implement the design, in 1823. Clement worked to high standards, but his machine tools were particularly elaborate. Under the standard terms of business of the time, he could charge for their construction, and would also own them. He and Babbage fell out over costs around 1831.

Some parts of the prototype survive in the Museum of the History of Science, Oxford.This prototype evolved into the "first difference engine." It remained unfinished and the finished portion is located at the Science Museum in London. This first difference engine would have been composed of around 25,000 parts, weighed fifteen tons (13,600 kg), and would have been 8 ft  tall. Although Babbage received ample funding for the project, it was never completed.

He later (1847–1849) produced detailed drawings for an improved version,"Difference Engine No. 2", but did not receive funding from the British government. His design was finally constructed in 1989–1991, using his plans and 19th-century manufacturing tolerances. It performed its first calculation at the Science Museum, London, returning results to 31 digits.

Nine years later, in 2000, the Science Museum completed the printer Babbage had designed for the difference engine.



Religious views

Babbage was raised in the Protestant form of the Christian faith, his family having inculcated in him an orthodox form of worship. He explained:

My excellent mother taught me the usual forms of my daily and nightly prayer; and neither in my father nor my mother was there any mixture of bigotry and intolerance on the one hand, nor on the other of that unbecoming and familiar mode of addressing the Almighty which afterwards so much disgusted me in my youthful years.

Babbage, (1864)

Rejecting the Athanasian Creed as a "direct contradiction in terms", in his youth he looked to Samuel Clarke's works on religion, of which Being and Attributes of God (1704) exerted a particularly strong influence on him. Later in life, Babbage concluded that "the true value of the Christian religion rested, not on speculative (theology) … but … upon those doctrines of kindness and benevolence which that religion claims and enforces, not merely in favour of man himself but of every creature susceptible of pain or of happiness.

In his autobiography Passages from the Life of a Philosopher (1864), Babbage wrote a whole chapter on the topic of religion, where he identified three sources of divine knowledge:

A priori or mystical experience

From Revelation

From the examination of the works of the Creator

He stated, on the basis of the design argument, that studying the works of nature had been the more appealing evidence, and the one which led him to actively profess the existence of God. Advocating for natural theology, he wrote:

In the works of the Creator ever open to our examination, we possess a firm basis on which to raise the superstructure of an enlightened creed. The more man inquires into the laws which regulate the material universe, the more he is convinced that all its varied forms arise from the action of a few simple principles ... The works of the Creator, ever present to our senses, give a living and perpetual testimony of his power and goodness far surpassing any evidence transmitted through human testimony. The testimony of man becomes fainter at every stage of transmission, whilst each new inquiry into the works of the Almighty gives to us more exalted views of his wisdom, his goodness, and his power.

Babbage, (1864)

Like Samuel Vince, Babbage also wrote a defence of the belief in divine miracles. Against objections previously posed by David Hume, Babbage advocated for the belief of divine agency, stating "we must not measure the credibility or incredibility of an event by the narrow sphere of our own experience, nor forget that there is a Divine energy which overrides what we familiarly call the laws of nature." He alluded to the limits of human experience, expressing: "all that we see in a miracle is an effect which is new to our observation, and whose cause is concealed. The cause may be beyond the sphere of our observation, and would be thus beyond the familiar sphere of nature; but this does not make the event a violation of any law of nature. The limits of man's observation lie within very narrow boundaries, and it would be arrogance to suppose that the reach of man's power is to form the limits of the natural world."

Main source of this articles is  https://en.wikipedia.org/

Thursday, 1 July 2021

Infrastructure of Computer for class Tenth and +2 level .

What is Computer?

ANS: A programmable electronic device designed to accept data, perform prescribed mathematical and logical operations at high speed, and display the results of these operations, is called Computer.

Who is father of Computer?

ANS: Charles Babbage, an English mechanical engineer and polymath, originated the concept of a programmable computer, considered the father of the computer.

 STRUCTURE OF COMPUTER

Computer has main four parts

       1.  Input devices

2. Output devices

3. CPU

4. Memory

1. Input devices

When unprocessed data is sent to the computer with the help of input devices, the data is processed and sent to output devices. The input devices may be hand-operated or automated. The act of processing is mainly regulated by the CPU. Some examples of input devices are:

Example:

Computer keyboard

Digital camera

Digital video

Graphics tablet

Image scanner

Joystick

Microphone

Mouse

Overlay keyboard

Real-time clock

Trackball

Touchscreen

Light pen

2. Output devices

Output device is any piece of computer hardware equipment which converts information into human readable form. 

 Printer

 Computer monitor

 PC speaker

 Projector

 Sound card

 Video card

3. CPU:

The control unit, ALU, and registers are collectively known as a central processing unit (CPU).

ALU

The ALU is capable of performing two classes of operations: arithmetic and logic. The set of arithmetic operations that a particular ALU supports may be limited to addition and subtraction, or might include multiplication, division

CU:

The control unit (often called a control system or central controller) manages the computer's various components; it reads and interprets  the program instructions, transforming them into control signals that activate other parts of the computeR.

REGISTER:

A processor register is a quickly accessible location available to a computer's processor. Registers usually consist of a small amount of fast storage

4. MEMORY:

In computing, memory is a device or system that is used to store information for immediate use in a computer or related computer hardware and digital electronic devices. The term memory is often synonymous with the term primary storage or main memory. An archaic synonym for memory is store.

IT is two types

PRIMARY MEMORY

It is again divided in two categories

RAM AND ROM

RAM IS Volatile memory is computer memory that requires power to maintain the stored information.

The two main types of volatile random-access memory (RAM) are static random-access memory (SRAM) and dynamic random-access memory (DRAM).

ROM: Read only Memory

SECONDERY MEMORY

You know that processor memory, also known as primary memory, is expensive as well as limited. The faster primary memory are also volatile. If we need to store large amount of data or programs permanently, we need a cheaper and permanent memory. Such memory is called secondary memory. Here we will discuss secondary memory devices that can be used to store large amount of data, audio, video and multimedia files.


 

Characteristics of Secondary Memory

These are some characteristics of secondary memory, which distinguish it from primary memory −

 It is non-volatile, i.e. it retains data when power is switched off

It is large capacities to the tune of terabytes

It is cheaper as compared to primary memory

Depending on whether secondary memory device is part of CPU or not, there are two types of secondary memory – fixed and removable.

Hard Disk Drive

Hard disk drive is made up of a series of circular disks called platters arranged one over the other almost ½ inches apart around a spindle. Disks are made of non-magnetic material like aluminum alloy and coated with 10-20 nm of magnetic material.

CD Drive

CD stands for Compact Disk. CDs are circular disks that use optical rays, usually lasers, to read and write data. They are very cheap as you can get 700 MB of storage space for less than a dollar. CDs are inserted in CD drives built into CPU cabinet. They are portable as you can eject the drive, remove the CD and carry it with you. There are three types of CDs

CD-ROM (Compact Disk – Read Only Memory) − The data on these CDs are recorded by the manufacturer. Proprietary Software, audio or video are released on CD-ROMs.

CD-R (Compact Disk – Recordable) − Data can be written by the user once on the CD-R. It cannot be deleted or modified later.

CD-RW (Compact Disk – Rewritable) − Data can be written and deleted on these optical disks again and again.

DVD Drive

DVD stands for Digital Video Display. DVD are optical devices that can store 15 times the data held by CDs. They are usually used to store rich multimedia files that need high storage capacity. DVDs also come in three varieties – read only, recordable and rewritable.

 Pen Drive

Pen drive is a portable memory device that uses solid state memory rather than magnetic fields or lasers to record data. It uses a technology similar to RAM, except that it is nonvolatile. It is also called USB drive, key drive or flash memory.

 source: https://en.wikipedia.org/