The Invention of Television

 Television

The transmission of photo  obsessed inventors as early as 1875 when George Carey of Boston proposed his cumbersome system. Only five years later, the principle of scanning a photo, line by line and frame by frame – still used in modern television sets – was proposed simultaneously in the USA (by W.E. Sawyer) and in France (by Maurice Leblanc). The first complete television  using the newly discovered properties of selenium – was patented in Germany in 1884, by Paul Nipkow. Boris Rosing of Russia actually transmitted images in 1907. The idea to incorporated cathode -ray tubes was proposed in 1911 by a Scottish engineer, Campbell Swinton. Another Scot, John Logie Baird, beat American inventor C.F. Jenkins to the mark by giving the first public demonstration of – a dim and badly flickering – television in 1926 in Soho, London. Britain commenced experimental broadcasting almost immediately thereafter. Irish actress Peggy O’Neil was the first to be interviewed on TV in April 1930. The Japanese televised an elementary school baseball match in September 1931. Nazi Germany started its own broadcasting service in 1935 and offered coverage of the 1936 Olympics. By November 1936, the BBC was broadcasting daily from Alexandra Palace in London to all of 100 TV sets in the kingdom. At the beginning there were many competing standards on both sides of the Atlantic. Baird’s technological solutions were trounced by Isaac Shoenberg and his team, set up in 1931 by Electric and Musical Industries . RCA refined its own system, as did the Dutch Philips. Not until 1951 were the standards for public broadcasting set in the USA and in Europe. But the Americans were the ones to grasp the commercial implications of television. Bulova Clock paid $9 to WNBT of New York for the first 20-seconds TV spot, broadcast during a game between the Brooklyn Dodgers and the Philadelphia Phillies in July 1941. Soap operas followed in February 1947 (DuMont TV’s A Woman to Remember) and the first TV news helicopter was launched by KTLA Channel 5 in Los Angeles on 4 July 1958. The first patent for color television was issued in Germany in 1904. Vladimir Kosma Zworykin, the Russia-born American innovator, came up with a complete color system in 1925. Baird himself demonstrated color TV transmission in 1928. Various researchers at Bell Laboratories perfected color television in the late 1920s. Georges Valenso of France patented a series of breakthrough technologies in 1938. But color TV became widespread only in the 1960.

Or gate and And gate.

 Or gate working

A=0,B=0 Both D1 and D2 don't conduct. Hence output y=0

A=0,B=0, D1 conducts D2 does not conduct.hence output y=1.

A=1,B=0  D1 conducts,D2 does not conduct. Hence output y=1 .

A=1,B=1, Both  D1 and D2 conduct.

Hence output y=1.

AND gate

It is realised by using two junction diode.

It has two or more inputs but one output.

It is expressed as y=A AND B=A.B (reads as y equals A AND B).

Conclusion

It all input are 1 them output is 1.

Working

If A=0,B=0, Both D1 and D2 are Forward biased and conduct.since both diodes are short circuited, output y=0.

If A=0,B=1,D1 is Forward blased but short circuited. 

Hence output y=0.

If A=1,B=0,D1 does not conduct. D2 is Forward biased but short circuited . Hence output y=0.

What do you do if your RAID server fails?

 Data recovery

RAID server failure is one of the dreaded work hazards you may have to face sometimes at your workplace. You tend to become incapable and powerless when you are unable to access data with a click. Data on a RAID array or volume can becomes inaccessible due to any of the following caused: . A faulty RAID controller • Multiple hard drive crash Malfunctioning upgrade or faulty striping • Defects with the MFT mount points. • RAID controller failure or configuration changed • Adding incompatible hard drives • Hardware conflicts • Software corruption • Virus infection, software and operating system upgrades In these above conditions, the following steps should be taken immediately to increase chances of getting critical files back . Shutdown the server and turn off the system. Do not try to reboot again. This may cause serious damage to your hard drive.   Do not attempt to recover data by yourself, friends or PC repair shops. This may result in permanent loss.  Do not continue to attempt a forced rebuild if you have already replaced a failed drive and tried to rebuild the array, but still can not access your data. This may wipe out your data. RAID data recovery utilities and software are not designed to restore data or rebuild RAID arrays from failing hard drives. This requires specialized equipment and professional training.  Swapping hard drives or re-ordering drives in a multiple drive RAID array may cause overwriting the striping and parity. This makes it nearly difficult to reconstruct your RAID array and salvage your company’s vital data. • Seeking professional help from professionally trained data recovery engineers is the sanest solution. Most data can be recovered from crashed hard drives and malfunctioning RAID servers by these experts only. What do Professional data recovery engineers do? Professional data recovery engineers have specialized equipment, a thorough knowledge of hex, drive structures, MFT mount points and offsets. The Professional engineers’ initial diagnosis determines whether each media device is accessible to their lab equipment. From all the data accessible to them from each media, they make a raw image onto a new media to help them analyse and assess the data loss. If some of the media is difficult to get hold of, they will test the components and closely check its internal condition to assess the level of physical damage sustained. The damaged components include electronics, write heads, magnets, drive motors and head assemblies. The raw images of the entire server media are used for logical recovery by examining the little level data sectors. Determination of both the exact layout of volumes, which span or are striped across multiple drives, is a must. Necessary fixes to the file system structures are to be decided upon to get access to important data. Servers that work on multiple drives are usually destriped  onto a different media so that file system repair can be done and the data files retrieved. It may be necessary to extract data directly from one or more fragments of the destriped photo. Professional programmers in this field have created a full set of software tools used by data recovery engineers to analyse,  fix & recover data from raw images drives to virtually all operating systems. The Validity of information is checked once a recovery has been successfully performed, and file lists created. A file recovery list is produced when your data is recovered. You can verify that your critical files are recoverable. The process usually takes 4-6 days though emergency data recovery services are also applicable.

Logic gate

 Ordinary algebra

Addition,substraction, multiplication, are basic operator in ordinary algebra.

0,1,2,3,4,5,6,7,8,9 ten digits are used known as decimal system.

Boolean algebra

OR,AND,NOT,  basic operator in Boolean algebra.

Binary digits are used (0,1) known as binary system.

Analong circuit

A current or voltage which varies continuously with time is called analog signal.

The electronic circuit which process analong circuit.

 Exp- Ammeter, voltmeter, Galvanometer.

Digital circuit

A current or voltage which does not vary continuously with time.only gives two discreate values high or low is called digital signal. The high value is denoted as 0.

The electronic circuit which process digital signal is called digital circuit.

Exp- digital multimeter, digital clock, morden computer,pocket calculator.

OR gate

It is realised by using two junction diodes.

It has two or more inputs but one output.

It is expressed as y=A+B=A OR B(reads as Y equuals A OR B.

Electro magnetic wave

Displacement current

Time rate of change of electric flux in gap between two plates of capacitor during changing or discharging process produces electric displacement current.

Electro magnetic wave

Stationary charge produce static electric field. A charge in uniform motion (stady current) produces magnetic field. These two field do not vary with time. Both time varying mutually perpendicular electric field and magnetic field can act as source of each other and generate electromagnetic wave in space.

Practically an a.c Circuit containg L(inductance)and C(capacitance)the acternating discharging and recharging of capacitor converts electric energy to magnetic energy and magnetic energy to electric energy. The exchange of energy produces oscillating nature of change in the Circuit. The oscillating change emits energy in the form of electromagnetic radiation or wave 🌊.

Properties of electro magnetic wave

The frequency of electro magnetic wave is equal to frequency of oscillating charge.

Depending upon L and C a wide range of wavelengths and frequency of electro magnetic wave 🌊 can be produced.

Electro magnetic wave can travel in vaccum with Speed of light.

Electro magnetic wave 🌊 travel in a direction perpendicular to both electro magnetic and magnetic wave.

Electro magnetic wave obey reflection,refraction, diffraction, polarisation.

Polarization of electro magnetic wave established transverse nature.

Your call phone and the enveroment .

Your cell phone and environment

However, the big numbers of users are also subject to changing trends for a number of reasons including improved features, fashion and accessories. This means that upgrades ar…An astonishing number of people own and use a cell phone (celular), with current figures total over 800 million worldwide. It has has become an important part of daily life, and improves business and travel opportunities, whilst providing the best possible level of communication across the globe.However, the big numbers of users are also subject to changing trends for a number of reasons including improved features, fashion and accessories. This means that upgrades are a regular occurrence, with each device being used for an estimated 12 to 18 months. This means that there is a lot of cell phone waste.Many users are not aware of the potential damage to the environment that incorrect disposal of cell phones  can cause. Incorrect disposal means throwing any cell phone away, which is the typical fate assigned to an unwanted device. However, components within it can have a terrible impact on the environment and so need special disposal. All cell phones (celular) contain persistent metals which do not degrade in the environment. They also contain bio accumulative metals which become toxic over period of time.For instance, cadmium which is present in a cell Phone is significant enough to cause damage in small doses. It is the seventh most harmful known chemical, and is capable of causing cancer and skin diseases. Cell phones also contain lead which causes liver damage in adults and neurological development problems in children when entered into the bloodstream. Other hazardous substances such as nickel and mercury provide further cause for concern.If not disposed of properly, the metals from the cell phone can leak into the environment through corrosion and cause a series of problems in the environment. If thrown away, it will go to a landfill where it will remain. As many elements do not decompose, the level of harmful toxins increases and so does the potential damage. Lithium can burn with water exposure, and so can potentially begin underground fires when present in big amount quantities. Any of the hazardous or poisonous substances could contaminate local water supplies or the nearby soil. If either of these is affected than the toxins enter the food chain with terrible results.In effect, incorrect disposal of the cell phone (celular) can create a form of poisoning. The immediate effects include health problems such as genetic or reproductive defects and detrimental effects upon the nervous system and delayed general development. The big term effect is global pollution. When waste that can not be broken down properly such as that in a cell phone  is decomposing it creates methane gas. Methane gas is more damaging than CO2 and so has major impact on global warming. Not many people realized that all this can be caused by disposing it in an incorrect manner.The best way to combat cell phone damage to the environment is to recycle it by returning it to a shop. This includes the accessories also. Some shops will ensure the product is send to developing countries for recycling. Others will reclaim the metal parts to prevent them going into a landfill. Some cell phone companies even make a charity donation for every recycled device to encourage the practice. The other possibility is that they will ensure the product is sent for proper disposal. This includes disposal of hazardous materials.Whichever option is used, the positive side effect is that less hazardous waste goes into the environment. Now that you know the facts, make sure that you dispose of your cell phone (celular) properly and remain environmentally sound with this one simple gesture.

Tipes of fire incident

Fire accident

Thousands of people die every year because of fire-related incidents, especially during the Christmas season. Thus, it is very important for us to be prepared for such emergencies. Each member of our family should know what to do in case of fire. More importantly, all of us need to know what to do to  fire. Plan Ahead One of the most important things that parents forget to teach their children is to prepare for emergencies, such as fire. Even at a young age, children should already be taught how to prevent fire and what to do in case there is fire. Fire drills have often been conducted in buildings and schools to help prepare building occupants and students in case of fire, so why can’t you have a fire drill in your home? The first step is to check your house for possible fire exits. See if the windows and doors in your house are big and tall enough to be used as possible fire exits. Make a floor plan for each room, ensuring that there are at least two ways to get out of the room to escape fire. In making the floor plan, you need to include crucial details, such as stairs, windows and hallways. After devising a floor plan, you should meet your children and parents and family members discuss your fire escape plan. You should also make sure that your family has devised a way of warning other members of fire, such as bells, door tapping, etc. It would be best if each bedroom of your house has a flash light and a bell. Lastly, select a safe place outside the house where everyone will go after escaping the fire. Preparing your family for fire emergencies It is wise to act out your evacuation plan with the whole family. Teach your children and family members how to stay close to the ground while escaping and is possible, let them memorize the way. Sometimes, the smoke caused by fire would make it very difficult to see the way, so it would really be wise if you and children know the way by heart. You and your children should also know that during fire, you should feel the door first before opening it. You should not open the door if it is hot. Instead, find another way you could escape your room or house. If the clothes of your children or any family member catch fire, tell them to fall to the ground and roll. This will help extinguish the fire. Make your house safe from fire Make sure that emergency numbers are placed near telephones. Such numbers should always be accessible and visible so that you can call authorities immediately when a fire breaks out. You should also ensure that smoke detectors are installed in key places in your house. Once smoke detectors are installed, you should check their batteries once in a while. Usually, the batteries of smoke detectors should be changed yearly. Place fire extinguishers in key locations. If your house has several floors, ensure that there is at least one fire extinguisher per floor. It would really be best if smoking is prohibited inside the house because many incidences of fire are caused by improperly discarded cigarettes. However, if smoking cannot be helped, make sure that nobody smokes in the bed.  let everyone know how to properly discard cigarette butts. No matter how many times you have taught your children that matches and lighters are dangerous, some will still play with them. Thus, it is advisable to keep all lighters and matches in places that your children cannot access. If possible, put them in locked drawers or cabinets

How to protect your computer

Protect your computer

Remov

media such as cds, floppy disks, usb keys that are infected and used in another system…These days it is a must to have a good, reliable virus protection program. There happens to be a many good free virus protection software packages out on the internet today. The only way to protect our pc and laptop today is using software that acts like a antidote to this disease.  using this software you can take preventive measures of stopping the disease before it infects the system.Remov media such as cds, floppy disks, usb keys that are infected and used in another system can carry the virus and infect the other machine. If you computer is infected with a virus you will need to remove the virus as soon as possible otherwise it can infect the system completely and spread to others. If a computer is infected by a computer virus the computer needs to be scanned by virus scanning software. When surfing the internet most likely you been infected with a virus, or some type of spyware, according to many virus detection agencies, the unprotected PC is infected on average within 20 minutes of normal internet usage. Many systems get infected every day, you must take safety measures or your system might get infected, and the virus might dishonest your data on your system. A Computer Worm is a self replicating program, the first worm to gain wide attention was the Morris Worm this infected a large number of computers and earned its writer 400 hours of community service and over $10000 in fines. When a virus infects you computer it can replicate itself, use up system resources, allow a user remote access, record keystrokes to the infected computer, it also has the ability to destroy personal data.You must take precautions because when you download it may contain spyware, adware or viruses, spyware and adware can collect personal data, record your browsing habits and no more about you. Ad and Spyware are programs that are automatically installed on your computer.When your computer is infected with a virus they are designed to alter your normal computer functions and spyware infections are used to spy on you, one way they do this is by recording your personal information. Many times adware, viruses and spyware find what is called a (back door) to install and replicated itself you in your computer.Downloading may sometimes cause error on the system or the entire computer system may crash. Many spyware or viruses are downloaded when downloading software and music. Many viruses can lay dormant without you knowing this, since you do not know it is there it can attack at any moment when least expect it, it could attack when typing a report and downloading important. Whether you have learning your lesson from a past experience or not, try not to download unwanted files or open email messages sent to you by people you do not know. Many people do all of this without any  understanding of just how vulnerable they are each time they are on the internet. Try to take precautions, find reputable software and install it to protect your system. There is free software on the web that will protect your system.