Advantages of glass reinforced plastic

Reinforced plastic has more strength and high resistance against weather, thus finding its use in outdoor applications and other many applications so it allows many advantages. Let us have a deep insight into the advantages of glass-reinforced plastic.

Advantages of glass-reinforced plastic :

• Glass can be easily drawn into the fibre from the molten state.
• Glass is cheaper and readily available.
• Glass fibre is relatively strong.
• In terms of plastic matrix materials, glass is chemically inert.
• One of the main reasons for using glass-reinforced is the fact that it does not conduct electricity.
• Resistant to corrosion.
• In its weight-to-potency ratio, glass-reinforced plastic is found.
• High strength plays a vital role when it comes to designing man load-bearing structures and glass-reinforced fulfils this need.
• Compared to other corrosion-resistant materials like titanium and stainless steel, it is very affordable.
• Glass-reinforced plastic has a high strength to weight ratio and high flexural strength making it an attractive lightweight material that builds strength into almost any finished component or product.
• The unique physical properties of glass-reinforced plastic make it extremely flexible meaning that almost any specifications can be easily tooled, moulded and manufactured.
• It probably won't corrode so you may not even have to finish it by painting it, just have the plastic producer dye it for you.
• It does not expand or contract anything like steel does.
• Glass-reinforced plastic will weight half the weight of aluminium and seventh of steel.
• Low transport cost.
• Long effective service life.
• Variety of joint system.
• Better hydraulic performance.

Advantages and disadvantages of ultrasonic machining

Ultrasonic machining also called ultrasonic vibration machining is a machining process in which, in the presence of abrasive particles, the material is removed from a part's surface by low amplitude and high-frequency vibration of a tool against the material surface. Let us have a deep insight into the pros and cons of ultrasonic machining in this article. 

Advantages of ultrasonic machining : 

• Ultrasonic machining can be used to drill circular or non-circular holes on very hard materials like stones, carbides, ceramics and other brittle materials.
• Machining of non-conducting materials like glass, ceramics and semi-precious stones easily.
• The cost of metal removal is low.
• As there is no heat generation in this process, there is no change in the physical properties of the job during machining.
• There are no residual stresses in the machined workpiece.
• This machining method produces highly accurate profiles and good surface finishes.
• The operation of the equipment is quite safe and noiseless.
• Free from burrs and distortions.
• Good surface finish and structural integrity.

Disadvantages of Ultrasonic Machining :

• The major limitation of the ultrasonic machining process is its comparatively low metal cutting rates. 
• Power consumption is high. 
• The depth of cylindrical holes is presently limited to 2.5 times the diameter of the tool. 
• Wear of tool increases so sharp corners become rounded. 
• The grain size and abrasive slurry are also the correct dimensions. 
• Periodic replacement of slurry is necessary for efficient cutting operations.
• The choice of tool metal is one of the most important decisions making for optimization of metal removing and tool cost.
• Replacement of tool is required for accurate machining as the high wear rate of the tool results in poor dimensional accuracy.
• Initial machining and tooling costs are very high.
• This process is not suitable for heavy metal removal operations.
• Softer materials give much difficulty in machining.
• Limited sized cavities are produced by this machining process.
• Minimum depth of the hole is achieved.

Engine nomenclature plate

The letters and numbers that make up an engine's model number are a series of codes to tell you the engine family, the number of cylinders, the emissions standard, the type of ignition, the capacity, the type of aspiration, and the generator set rating.

The Model Number :

It is easiest to demonstrate with a particular engine model a 1206E-E66TAG for instance.

• The first two digits – 12 – tell you the engine family, in this case, the 1200 Series.
• The next two digits – 06 – tell you the number of cylinders, in this case, six.
• The next letter – E – confirms the engine meets EU Stage IIIB/U.S. EPA Tier 4 Interim.
• The E after the hyphen says it has electronic fuel injection. If there were no letter, it would have a mechanical injection.
• The next two digits – 66 – give you the engine capacity in decilitres, in this case, 6.6 liters
• The following letters give their type of aspiration. In this case, T means it is turbocharged, and A says it is air-to-air charge cooled. W would mean it was water-to-air charge cooled, and if there were no letters, it would be naturally aspirated.
• The G in brackets gives the engine’s generator set rating.

You can also check out Engine nomenclature

Difference between carburizing and nitriding

What is carburizing?

Carburizing is a heat treatment process that diffuses when the metal is heated in the presence of carbon-bearing material, such as charcoal or carbon monoxide, in order to make the metal harder.

Example - Precision gears

What is Nitriding?

Nitriding is a heat treatment process that diffuses nitrogen into a surface of the metal to create a case-hard surface are most commonly used on low-carbon, low-alloy steels, but also in medium and high-carbon steels, titanium, aluminium and molybdenum.

Example: Crankshafts

Main difference : 

Carbon is made to diffuse through the metal surfaces in carburizing whereas in nitriding nitrogen is made to diffuse.

Let us have a deep insight into the comparison and difference between carburizing and nitriding. 

Difference : 

• Nitriding does not cause smash or rift or any change in metal properties because it does not need to sprinkle to get surface hardening and also it doesn't need to high temperature as carburizing.
• Carburizing and nitriding both are heat-treatment processes and used for surface hardening of the low carbon steels and also medium and high carbon steel.
• Carbon is diffused on to the surface of the metal in carburizing whereas nitrogen is diffused in the nitriding process. 
• Carburizing has done at a very high temperature and carbonaceous environment while nitriding has done at low temperature and in a nitrogen environment. 
• Nitriding produces harder and stronger cases as compared to carburising.

For the graphically view Hardness versus Case Depth HRc 60 is a hardness measurement on the Rockwell C scale, typically this value is the benchmark for a carburized steel, remember when started out in heat treatment you would sometimes use ‘hardened metal files’ and rub these across a surface of the carburized steel to check if the steel had sufficient hardness (file would polish) or if the surface was poorly treated and had low surface hardness, the file would scratch in to the surface of the steel.

When considered in gears :

Carburized gears feature a much deeper, hardened layer that gradually decreases its hardness to the core hardness. This structure provides superior surface contact fatigue properties and ductility/impact resistance and strength of the core. Moreover, like a needle roller bearing surface in the planet gears, sufficient case depth obtained during the carburizing process is required.

Nitride gears can have a very hard and brittle white layer on the surface. It is not removed it can be prone to flaking and cracking leading to heavy surface fracture and gear failure. The hardened case depth is considerably thinner than in similar carburized gears and transitions immediately behind the case to the core hardness.

Explore more information:

1. Advantages and Disadvantages of Carburizing

Advantages and disadvantages of Electo-chemical Grinding

Electro-chemical grinding is also called electrolyte grinding. Electrolyte grinding is a modification of both the grinding and electrochemical machining. In this process, machining is affected both by the grinding action and by the electro-chemical process. Hence, it may also be called mechanically assisted electrochemical machining. Let us have a deep insight into the pros and cons of electrochemical grinding. 

Advantages of Electrochemical Grinding :

• Work is completely free of burr.
• No heat is generated.
• No heat is no distortion are developed.
• Very little pressure is exerted on the work.
• No wheel wear is found.
• High metal removal rates are possible.
• This process also used for grinding of hard material.

Disadvantages of Electrochemical Grinding :

• Cost is high.
• Metal removal rates are comparatively low for some material.
• Power consumption is high.

Electrochemical Grinding

Electro-chemical grinding is also called electrolyte grinding.

Electrolyte grinding is a modification of both the grinding and electrochemical machining.
In this process, machining is affected both by the grinding action and by the electro-chemical process. Hence, it may also be called mechanically assisted electrochemical machining.

In ECG the metal bonded grinding wheel impregnated with a non-conductive abrasive is made the cathode and the workpiece the anode as in ECM.
The electrolyte which is usually sodium nitrate, sodium chloride, sodium nitrite, potassium nitrite with a concentration of 0.150 to 0.300 kg/litre of water, is passed through a nozzle in the machining zone in order to complete the electrical bridge between anode and cathode.
The work and wheel do not make contact with each other because they are kept apart by the insulating abrasive particles which protrude from the face of the grinding wheel.
The electrolyte is carried past the work surface at high speed by the rotary action of the grinding wheel. metal is removed from the workpiece by the simultaneous electrolytic and abrasive action.

It can be seen that the process is similar to conventional grinding in that an abrasive grinding wheel is used, and the work is fed against the rotating wheel. In fact, 10% of the work is removed by abrasive cutting and 90% by electrolytic action.

The grinding wheel used are conventional shape and structure metal bond, diamond grit wheels are used for grinding tungsten carbide tips. carbon bond wheels are used upon the hard alloy steels such as the stainless steels. 

The machine is similar in design to surface grinder or tool and cutter grinder and equipment includes a tank, filter and pump for the supply of electrolyte and a power unit for delivering a heavy D.C current. The current applied is in the range of 50 to 3000 A at 4 to 10 V.

Accuracy :

• Tolerance is about +0.02 to -0.02 are held on the rather complex grinding operation.
• For closer tolerances, the proportion of material removed by abrasive should be increase.
• Surface finish is held in a range of 0.2 to 0.4 micron on carbide and 0.4 to 0.8 micron on steel.
• A sharp corner is difficult to obtain and minimum radius of 0.2 mm.

Applications :

• Any material which is electrically conductive may be ground by the electrolytic process.
• Mainly used for resharpening and reconditioning of carbide tools and other materials that are hard to grind.
• Grind and cut thin sections
• Grind difficult materials without distortion or burr.

For more to know about: Advantages and disadvantages of Electo-chemical Grinding

Stuxnet Documentry

Since Stuxnet is a worm, it has a lot of similarity with other worms. What differentiated Stuxnet from any another malicious worm is how differently capable it was to induce damage on its target. Its capability includes exploiting multiple zero-day vulnerabilities, modifying system libraries, attacking Step7 installations (Siemens’ SCADA control software) and running an RPC server and installing signed drivers on Windows Operating Systems. Stuxnet spread via several methods, but all methods were integrated to infect PLCs only. Stuxnet is capable enough auto update itself. It looks for new version in the local area network. Stuxnet hides its presence from the control panel, which is the reason behind unexplained problems in the operation cycle. It remained opaque to its user because the control panel always shows normal functioning.

Journey of Stuxnet

The first time, Stuxnet was detected by a Belarus-based AV company called VirusBlockAda on June 17, 2010. In the initial phase of the analysis, it was not clearly known, what was the exact reason behind this malware. Even after knowing the target, it was difficult to establish the fact that how it was affecting the control system. Later some of the security experts like Ralph Langner, Symantec engineers wrote a complete technical paper which provided every detail about Stuxnet and how it affected the control systems, particularly the Iran nuclear facility. Although Iran never accepted this fact but experts believe that Stuxnet hit them.

Stuxnet is a vicious piece of code, which unprecedentedly and masterfully attacked in three phases; first, it targeted Microsoft Windows systems and networks, by repeatedly replicating itself. Then it searched for Siemens Step7 software, which is a windows based platform, used to program the ICS that operate equipment in the nuclear facility. Finally, it compromises Programmable Logic Controllers (PLC's).

Stuxnet gets itself installed in the industrial root kit which feedbacks the false data to outside controllers so that no alarm or shutdown is done due to unexpected behavior of the process. This idea made Stuxnet more vulnerable because it was able to achieve a large part of its task without getting caught.

The idea of Stuxnet was not only to destroy the nuclear facility completely but also to halt the program as adversely as possible. Stuxnet created a difficult situation for Iranian engineer because even if they were changing the rotors frequently they are not able to get the exact reason behind this error. Stuxnet really frustrates the Iranian engineer to their core.

Infection

Stuxnet enters the network through a malicious computer which is already infected by a USB flash drive. For entry in any system, Stuxnet shows a digital certificate that gives an illusion to the system that it comes from a reliable source, thus this worm is able to evade the automated detection system. Once Stuxnet gets inside the local network it proceeded to infect all the machines running Microsoft windows.

Search

After infecting the systems, Stuxnet checks whether a given machine was a part of the targeted ICS or not. By analysis of Stuxnet it was clear that even if Stuxnet gone wild in the world, it was never meant to affect any other device but only Natanz Nuclear plant in Iran. It happened because the controller which Stuxnet was searching was present in Iranian Nuclear Power Plant.

Auto-Update

Stuxnet does not need any kind of internet service to update itself, if any updated
version is available on the local network, it can easily update itself. For auto updation, Stuxnet used RPC (Remote Procedure Call) and wait for connections.

Compromise

The worm then compromises the logic controllers of the target system by using “Zero-day” vulnerabilities. It has been reported that Stuxnet attacked only those PLC systems which were installed by Vacon and Farao paya. Stuxnet monitored the frequency of the attached centrifuge rotors and attacked only those controllers which were spinning in some specific range. Then it installed the payload on the PLC's which resulted in periodic modification of the frequency and as a resultant rotational speed of rotor change.

Facts of Stuxnet

In order to demonstrate the sophistication of this effort, we would like to point out that Stuxnet utilized various vulnerabilities: 

“Zero-day” Vulnerabilities

Stuxnet exploited a lot of different vulnerabilities, four of which were zero-day
vulnerability. Some of the Zero-day attacks is seen before the Stuxnet but concatenating different Zero-day attacks were massive and infectious. Zero-day attack is briefed below:

• Printer-Spooler vulnerability: This service is used to transfer the malicious code and then execute it on other systems in the shared network. Using this vulnerability Stuxnet copies itself from one machine to another machine via shared printers which are publicly available in the network.
• .LNK vulnerability: A .LNK file is used to launch the malicious code on an infected windows machine. No test is done to verify the file even by anti-virus. The vulnerability is utilized in Stuxnet to reference a file in an infected drive that holds the virus. After installing of the virus, Stuxnet hides the .LNK file as well as the source file. Later autorun.inf is used to automatically run the file in removable media.
• This vulnerability utilizes a similar vulnerability used in Conficker attack. Stuxnet uses this flaw in RPC call to infect potential hosts on the network. This vulnerability first ensures whether the host system has Stuxnet installed or not, if it's not infected, then it sends the Stuxnet to the uninfected machine.

Stuxnet probe phase

Stuxnet secretly recorded the every normal operation performed for full operation cycle. It plays all the recorded data back to the controllers to make sure whether industrial rootkit used to fake the data is enabled or not. During this infect other computers. Maintain the database of the infected computer, observe the variations and changes, and keep track of successfully infected systems.

Pre-Attack Phase

During the pre-attack phase, Stuxnet utilizes various tactics to spread itself to other systems: 

• USB Flash Drives-The PLCs connected to the computers whose main functionality is to control and monitor them is not connected to the internet. In Natanz Nuclear plant, the infected flash drives may have been introduced to the control computers via some other external contractors working at the plant.  
• WinCC-SCADA systems are hard coded with a password and used to connect into WinCC and attack the database using SQL commands to upload and start a copy of itself on WinCC computer. Stuxnet infected all the Siemens SIMATIC Step7 industrial projects that are opened on an infected system. Some modification is done on the .exe file and DLLs (Dynamic Link Library) in WinCC, so that executes Stuxnet code as well. 
• Network Shares-Stuxnet also used windows shared folder to spread the virus to the local network. Infected computer placed a dropper file in the shared folder and schedule a task to execute this file. There is a debate between experts about the scheduled execution of the file 

Contributed By: Vivek Pratap Chaurasia

Email id: vivekpratap07@gmail.com

Chemical Machining

Chemical machining is stock removal process for the production of desired shapes and dimensions through selective or overall removal of material by a controlled chemical attack with acids or alkalis.

The metal is gradually transformed into metallic salt by chemical reaction and is ultimately removed in this form.

The process can be suitably applied to different types of operation such as milling on a milling machine, blanking, and engraving. The chemical machining process can be classified as :

• Chemical milling
• Chemical blanking 
• Chemical engraving

Chemical milling :

Chemical milling sometimes called chilling or contour or etching is used mainly to produce shapes by selective or overall removal of metal parts from the relatively large surface area.

The main purpose is to achieve shallow but complex profiles, reduction in weight by removing unwanted material from the surface as in the skin of an aircraft.

Chemical milling complete in four steps :

1. Cleaning
2. Masking
3. Etching
4. De-masking

Application of CHM :

• Chemical machining has been applied successfully in a great number of usages where the depth of material removal is critical to a few microns and tolerance are closed.
• The surface finish obtained in the process is in the range of 0.5 to 2 microns.
• One of the major application of CHM is in the manufacture if burr-free, intricate stampings.

You know to check it out: Advantages and disadvantages of chemical machining 

Advantages and disadvantages of chemical machining

Chemical machining is stock removal process for the production of desired shapes and dimensions through selective or overall removal of material by a controlled chemical attack with acids or alkalis. The metal is gradually transformed into metallic salt by chemical reaction and is ultimately removed in this form. Let us have a deep insight into the pros and cons of chemical machining in this article. 

Advantages of Chemical Machining :

• Components are produced burr-free.
• The process is relatively simple.
• Can be applied to almost any material.
• Thin sections.
• Several components can be produced simultaneously.
• The process does not distort the machined components.
• Most difficult to machine material can be processed.
• High surface finishing is possible.

Disadvantages of Chemical Machining :

• The metal removal rate is slow.
• Metal thicker than 2 mm can not be usually machined.
• High operator skill is required.
• Corrosive etchant damages the equipment.
• Required the handling of dangerous chemicals.
• Disposal of potentially harmful byproducts.

Types of all wheel drive system

All-wheel drive cars have a different drive system according to the road surface. There are mainly four types of the all-wheel drive system.

1. Part-time all-wheel drive
2. Full-time all-wheel drive
3. Automatic all-wheel drive
4. Selectable all-wheel drive

The part-time all-wheel-drive system cannot be used in the non-slippery condition you will have to drive such cars in rear-wheel drive condition.
AWD is not necessarily that it is a full-time all-wheel drive and 4 wheel drive is not just four off-road vehicles. They both are same but there is a minor difference between AWD and 4WD.

• Part-time all-wheel drive 

This is a temporary all-wheel-drive system. In normal condition, just one axle is driven while in slippery condition another axle is engaged by the driver by leaver or button.

This type of all-wheel drive does not have a centre differential.

When all-wheel drive is engaged the front and rear driveshafts are mechanically connected and rotated at the same speed.

• Full-time all-wheel drive 

This is a permanent all-wheel drive or permanently engaged all-wheel-drive system.

All-wheel is powered at all times and the vehicles with full-time all-wheel drive are equipped with a centre differential that lets each wheel travel different distances while turning.

This type of all-wheel drive used both on and off-road condition.he

In slippery condition, the centre differential can be locked, whether manually or automatically depending on the vehicle.

• Automatic all-wheel drive 

This is an on-demand all-wheel drive. Under the normal driving condition, only one axle is powered. when wheel slipping occurs at that condition the driving driveshaft rotates faster than the driven driveshaft and a multi-plate hydraulic clutch or other similar traction control device locks and engages another axle.

The difference between the traction devices that are used in full-time all wheel drive and automatic all wheel drive systems is that the device used in automatic all wheel drive system replaces the center differential.

• Selectable all wheel drive 

In selectable all wheel drive driver can choose between the 2WD mode or 4WD mode with automatic distribution of torque via viscous coupling vehicle behaves like the one with full time all wheel drive.

4WD with locked differential behaves like part-time all wheel drive.

All wheel drive differential

It is important to know how all-wheel drive works on your car.

Most of manual AWD cars have 3 differential one in between the front wheels, one in between the rear, and one in between the other two. but in a cheaper car like SUVs designed for city driving uses only 2 differential one front and one rear, and a viscous coupling in the centre.

For better understanding, you should know first 
Types of the all-wheel drive system 
Difference between AWD and 4WD.

All wheel drive benefits

There is a lot more difference between AWD and 4WD or difference between front wheel drive and real wheel drive but more important to know the benefits of all-wheel drive.

If you live in an area frequently hit by harsh winter storms and paralyzed by slippery streets then you have to think about to buy AWD car but for those who don't have to deal with such difficult climates, you might not need it as much as you think because the cost is the main issue in AWD cars.  

Another case people sometimes buy an AWD or 4WD vehicle for the occasional off-road outing while 90 per cent of the time they will be sitting in traffic or using the vehicle on paved roads. This would save them money both on the price of the car plus the lower fuel costs.

Disadvantages of all wheel drive

An all-wheel-drive vehicle is one with a powertrain that can supply power to all its wheels, whether full-time or on-demand. Let us have a deep insight into the disadvantages provided by car used to all-wheel drive.

Disadvantages of all-wheel drive :

• More expensive to buy.
• Uses more fuel.
• Higher maintenance and repair costs.
• Tires need to be the exact same size may need 4 new ones if one destroyed.
• Better traction in slippery road conditions can make a driver over-confident in their ability to stop or turn, often resulting in an accident.
• Heavy more parts mean more weight.
• Unusual handling characteristics.

Difference between front wheel drive and rear wheel drive

Both the rear-wheel drive and front-wheel drive are relatively same just a minor difference FWD stands for front-wheel-drive which means that the engine is powering only the front two wheels while RWD stands for rear-wheel-drive means that the engine is powering the rear wheels. Let us have a deep insight into the comparison and difference between them.

Difference between FWD and RWD :

• The clutch, gearbox and differential in FWD are made from one unit and are called transaxle where the clutch and gearbox are at the front in RWD while the differential is driven at the rear by the propeller shaft.
• RWD vehicle is being pushed from behind while an FWD vehicle is being pulled.
• The fuel consumption is usually similar to the FWD and RWD vehicles.
• In FWD the front wheels of these vehicles are exclusively powered while in RWD the power from the power train is transmitted to the rear wheels via a driveshaft.
• Only front wheels are responsible to drive the vehicle in FWD while RWD real wheels are responsible to drive the vehicle.
• RWD cars usually tend to be more powerful and sportier than FWD.
• The front-wheel weight in FWD is higher than in RWD.
• FWD configuration provides low floor compared to RWD as there is no longer propeller shaft.
• Because of the presence of differential at the front, there is more luggage space at the back in FWD compared to RWD.
• The FWD vehicle has more adhesion on the road than RWD due to more weight on the front wheel.
• In FWD, the weight shifts to the rear wheel are reduced on a gradient or while accelerating, which is not desirable, thus reducing tractive effort.
• The steering is hard because of more weight on the front wheel in FWD and there is always understeer.

RWD cars offer a better overall driving experience and are the better cars for drifting and can accelerate faster and provide better grip. As for reduced traction in wet conditions, this can be remedied with modern electronic traction control but are almost always more expensive.

On the other hand, FWD cars may not be as fun to drive, but they are cheaper and more sensitive. It makes more sense to travel within the city at low speeds and to use cheap FWD cars in general on a daily basis.

Front-Wheel Drive cars : 

• Maruti Suzuki Dzire
• Alto K10
• Wagon R
• Hyundai Verna
• Skoda Rapid
• Tata Indigo 

Rear Wheel Drive cars :

• Chevrolet Tavera 
• Mahindra Scorpio
• Mahindra Bolero

Cheapest rear wheel drive car

Top Affordable Rear Wheel Drive Cars

• Chevrolet SS

• Nissan 370Z

• Chrysler 300/Dodge Charger

• Dodge Challenger

• Scion FR-S/Subaru BRZ

• Hyundai Genesis Coupe

• Mazda MX-5

• Chevrolet Camaro

• Ford Mustang

• Smart Fortwo

• Nissan Z

• Jeep Cherokee

• Toyota MR2

• Dodge Charger

• BMW 3 Series

Best all wheel drive wagons

The best all-wheel drive wagons are listed below :

• Audi Allroad
• BMW 3 Series Sports Wagon
• Ford Flex
• Lincoln MKT
• Mercedes-Benz E-Class 4MATIC Wagon
• Mini Cooper S Countryman ALL4
• Subaru Outback
• Toyota Venza
• Volvo XC70
• Volvo V60 T6 R-Design AWD

Best all wheel drive convertibles cars

The best all-wheel drive convertible cars are listed below :

• Audi A3 Cabriolet
• Audi TT/TTS Roadster
• Audi A5/S5/RS5 Cabriolets
• Audi R8 Spyder
• Bentley Continental GT Convertible
• BMW 4 Series Convertible
• BMW 6 Series
• Porsche 911 Cabriolets
• Porsche 918 Spyder

Top least expensive All Wheel Drive cars

Top least expensive all-wheel drive cars are listed below :

• Suzuki SX4
• Subaru Impreza
• Subaru Legacy
• Subaru Forester
• Nissan Juke
• Toyota Matrix
• Subaru XV Crosstrek
• Kia Sportage

Best all wheel drive cars and SUVs

Top 10 All Wheel Drive cars are listed below :

• Subaru Outback
• Subaru Crosstrek
• Subaru Forester
• Audi Q5
• Chevrolet Suburban/GMC Yukon XL
• Jeep Wrangler
• Chevrolet Tahoe/GMC Yukon
• Jeep Grand Cherokee
• Toyota 4Runner
• Ford Expedition

Difference between JAVA and Javascript

What is JAVA?

Java was first released in 1995 by Sun Microsystems. It is a class-based and object-oriented server-side programming language that is used for a myriad of technical purposes. It runs in a virtual machine and was designed to follow the “write once, run anywhere” methodology, therefore allowing the Java code to run on any platform that supported it without having to recompile.

What is JavaScript?

The JavaScript is a Object Oriented Scripting language, developed by Netscape, Inc., is not part of the Java platform. 

JavaScript does not create applets or stand-alone applications. In its most common form, JavaScript resides inside HTML documents, and can provide levels of interactivity to web pages that are not achievable with simple HTML. 

Key differences between Java and JavaScript:

	JAVA	Javascript
1	Java is Object Oriented Programming language.	Javascript is Object Oriented Scripting language.
2	It creates applications that run in a virtual machine or browser.	It runs inside browser only.
3	It is compiled.	It is interpreted.
4	Java is high-level, static,compiled and strongly type language.	JavaScript is text based , dynamic and weakly typed language.
4	It has block based scope.	It has Function based scope and object based context.
5	It has an implicit this scope for non-static methods, and implicit class scope.	It has implicit global scope.
6	It has constructors.	It has standard functions.
7	I t is class-based.	It is prototype-based.
8	functions are only variadic if explicitly marked.	functions are variadic.
9	It allows methods in an object to be redefined independently.	object are tied to its class, and cannot be redefined at runtime.
10	Java program has file extension “.Java” and after compilation it becomes “.class” file that contains bytecodes which is executed by JVM : Java Virtual Machine.	JavaScript file has file extension “.js”
11	In Java there is different datatypes like int, float, string, etc	There is var keyword is used to define variable
12	Example: class HelloWorldApp {   public static void main(String[] args) {   System.out.println("Hello World!"); } }	Example: <html> <body> <p>Beginning text</p> <script> alert('Hello, World!') </script> <p>End text</p> </body> </html>