Merge pull request #120 from nishanthebbar2011/branch1

New Post: Blog Articles for final week added

blog_src/_config.yml

@@ -46,11 +46,11 @@ exclude: ['package.json', 'src', 'node_modules']
 
 # extra plugins
 plugins_dir: 
-  ['jekyll-paginate']
+ ['jekyll-paginate']
 
 # Gems
 plugins: [jekyll-paginate]
-# gems: [jekyll-paginate, jemoji]
+gems: [jekyll-paginate, jemoji]
 
 #make 5 articles per page
 paginate: 6

blog_src/_data/authors.yml

@@ -490,3 +490,22 @@ RosaGeorge31:
   author_image: RosaGeorge.jpeg
   user_description: 'Born to Code!'
   email: [email protected]
+nishanthebbar2011:
+  name: Nishanth P Hebbar
+  github: nishanthebbar2011
+  author_image: Nishanth.jpg
+  user_description: 'If it is to be, it is up to me'
+  email: [email protected]
+HarshitRanjan:
+  name: Harshit Ranjan
+  github: HarshitRanjan
+  author_image: HarshithRanjan.jpg
+  user_description: 'Never settle with what you are!'
+  email: [email protected]
+aditya-834:
+  name: Aditya Rangarajan
+  github: aditya-834
+  author_image: AdityaRangarajan.jpeg
+  user_description: 'I am not lazy, I just really enjoy doing nothing!'
+  email: [email protected]
+

blog_src/_posts/2017-12-24-Speed_Printing.md

@@ -0,0 +1,69 @@
+---
+layout: post
+title: "Speed Printing"
+author_github: HarshitRanjan
+date: 2017-12-28 17:05:21
+image: '/assets/img/'
+description: "Here's a breakdown of how the CLIP technology helps in printing faster than the conventional stereolithographic printers"
+tags:
+- Speed Printing
+- Stereolithography
+categories:
+- Piston
+github_username: 'HarshitRanjan'
+---	
+
+
+## Introduction
+ 3D printing technology is often used to construct highly complex objects of different kinds, properties and materials. Despite its numerous advantages, one major drawback of 3D printers is its traditionally slow speed. This is where it fails miserably, in its large scale applicability, against other major manufacturing processes like injection moulding. To overcome this major industry challenge, several 3D companies have come up with more updated and efficient technologies that guarantee quick speeds and utmost accuracy. One of the successful and modern technology is **CLIP (short for, continuous liquid interface production)**.
+
+> A typical 3D printing machine such as Stereolithography (SLA) can take several hours to print a 55mm diameter object and maybe several days to complete a larger object, while injection moulding takes minutes for the same.
+
+Additive manufacturing startup **Carbon 3D** has developed an efficient technology that helps manufacturers cut their costs, waste less energy and materials while speeding up the time it takes to get from concept to product on the market. Some years back, it launched the M1 3D printer. The M1 used UV light in a process called stereolithography to *grow* objects from a pool of photopolymer resin which was not at all out of the box. But Carbon's technology allowed it to print in a steady stream rather than layer-by-layer, letting it churn out sophisticated objects up to 100 times faster than traditional stereolithography printers
+
+In order to properly understand how the CLIP technology differs, we need to learn about the basic principles involved in Stereolithography. It's the process by which a uniquely designed 3D printing machine, called a stereolithograph apparatus (SLA) converts liquid plastic into solid objects layer-by-layer.
+
+### How Stereolithography works: 
+
+**From CAD to STL:**
+
+> CAD files are digitalized representations of an object to be printed. 
+
+There are many different ways to 3D print an object. But nearly all of them utilize **computer aided design (CAD)** files. In 3D printing, CAD files are translated into **Standard Tessellation Language (STL)** that 3D printing machines can easily understand. Since additive manufacturing works by adding one layer of material on top of another, CAD models are broken up into layers before being printed in three dimensions.
+
+### Basic Working
+
+A SLA machine has four main parts: a tank that can be filled with **liquid plastic or photopolymer**, a **perforated platform** that is lowered into the tank, an **ultraviolet (UV) laser** and a **computer** controlling the platform and the laser. It starts with an excess of liquid plastic called as photopolymer, which is cured or hardened to form a solid object.  In the initial step of the SLA process, a thin layer of photopolymer is exposed above the perforated platform. The UV laser hits the perforated platform, "painting" the pattern of the object being printed. The UV-curable liquid hardens instantly when the UV laser touches it, forming the first layer of the 3D-printed object. Once the initial layer of the object has hardened, the platform is lowered, exposing a new surface layer of liquid polymer. The laser again traces a cross section of the object being printed, which instantly bonds to the hardened section beneath it. This process is repeated again and again until the entire object has been formed and is fully submerged in the tank. The platform is then raised to expose a three-dimensional object. After it is rinsed with a liquid solvent to free it of excess resin, the object is baked in an ultraviolet oven to further cure the plastic. 
+SLA can go **top-down** (build platform facing up, descending while printing) or **bottom-up** (build platform facing down, ascending while printing). The bottom-up approach has the advantage that the object can be much larger than the vat itself, as the other approach requires the vat to contain the object. Bottom-up approaches also have an extra step where once a layer is done, the vat needs to 'rock' it off the resin ("flexing and peeling the bottom of the vat away from the hardened photopolymer" so that the build platform can be pulled up cleanly.
+
+### Continuous Liquid Interface Production
+
+![CLIP](/blog/assets/img/Speed-Printing/image1.jpg)
+
+
+CLIP, which stands for Continuous Liquid Interface Production, eliminates shortcomings of other 3D printing technology by emphasizing a *tunable photochemical process* over a traditional mechanical approach. The control over the solidification occurs by balancing oxygen and light to discriminately cure photo liquid resin. Continuous Liquid Interface Production technology uses components as shown in the image above such as
+
+  1. BUILD PLATFORM
+  2. UV CURABLE RESIN
+  3. OXYGEN-PERMEABLE WINDOW
+  4. DEAD ZONE 
+  5. PROJECTOR
+
+![CLIP](/blog/assets/img/Speed-Printing/image2.jpg)
+
+## How the CLIP Process Works
+
+Carbon's technology works through two phases. The first one, CLIP, consists of shaping the part by projecting a light through an oxygen-permeable window into a reservoir of UV-curable resin. As the UV images are projected in a sequence, the part solidifies and the build platform rises, allowing 3D objects to continuously grow without interruption. This is similar to SLA with a slight difference: it introduces oxygen into the liquid resin in order to control what is known as the *dead zone*. 
+
+> The *dead zone* is a thin, liquid interface of uncured resin between the window and the printing part where the light passes through. 
+
+During the development stage, images are fed into the system using a digital light projector via an oxygen permeable UV transparent screen. This process takes place beneath a liquid resin bath. 
+
+![CLIP](/blog/assets/img/Speed-Printing/image3.jpg)
+
+The second phase consists of thermal curing by baking the parts in a forced circulation oven to set off the properties of the materials. Through this process, a secondary chemical reaction sets off and causes the materials to adapt and strengthen, ultimately achieving desired engineering-grade mechanical properties.
+
+### Comparison:
+Now, as we are aware of the basic working of both the techniques, we can now understand what sets them apart in terms of speed. CLIP is much faster than bottom-up technologies that require a **peel** step between every layer as the cured layers stick to the resin container. That is, by far, the slowest step of SLA printing with most modern light sources. CLIP is a bottom-up technique that doesn't require a peel step, because the vat creates an oxygen layer over the window that keeps the resin from curing directly on the surface and sticking. In that way, it arguably performs more like a top-down printer than a bottom-up printer. 
+
+

blog_src/_posts/2017-12-24-War_of_the_Currents.md

@@ -0,0 +1,50 @@
+---
+layout: post
+title: "War of the Currents"
+author_github: aditya-834
+date: 2017-12-28 23:33:44
+image: '/assets/img/'
+description: 'The war that changed the world more than both the world wars.'
+tags:
+- Tesla
+- Edison
+- AC/DC
+categories:
+- Diode
+github_username: 'aditya-834'
+comments: true
+---
+
+
+![current](/blog_src/assets/img/War-of-the-currents/image1.png)
+**Thomas Edison**
+
+
+![current](/blog_src/assets/img/War-of-the-currents/image2.png)
+**Nikola Tesla**
+
+At the end of the 19th century, the world witnessed one of the greatest scientific feuds of all times, which changed the course of the history.
+Three brilliant inventors, Thomas Edison, Nikola Tesla and George Westinghouse, battled over which electricity system—direct current (DC) or alternating current (AC)–would become standard. This would go on to be known as the 'War of the Currents'.
+
+By 1880, Edison had created a model for the incandescent lamp that was commercially viable. But to make a profit out of the electric lights
+that he had invented, he realized that electricity would have to be brought to people's homes. Thus he began devising a system for generation and distribution of power. Edison's distribution system would supply 110 V DC voltage. In 1882, Edison opened the first ever electric power plant in Pearl Street, New York. The problem with Edison's system was that it could only deliver electricity within a half-mile radius from the plant.
+
+![current](/blog_src/assets/img/War-of-the-currents/image3.png)
+
+## The first induction motor
+
+Two years later, A young Serbian engineer, Nikola Tesla immigrated to America and started working under Edison. He improved Edison's existing DC system in order to interest him in an AC motor that he had been developing. But Edison, a firm supporter of DC, said that AC has no future.
+
+Tesla quit his job in 1885 and a few years later received a number of patents for his AC technology. In 1888, he sold his patents to industrialist George Westinghouse, whose Westinghouse Electric Company had quickly become an Edison competitor. Feeling threatened by this competition, Edison started a propaganda to malign George Westinghous and his AC System in the eyes of the public. As a part of this propaganda, Edison electrocuted a number of animals just to prove how dangerous high voltage AC is. Edison even suggesting electrocution as way of executing criminals and in 1890 convicted murderer William Kemmler became the first person to die on an electric chair which was powered by a Westinghouse generator. This marked one of the darkest events of the war.
+
+With the advent of the alternating current transformer, high voltage AC produced by the generators could be stepped down to lower voltages within the safety standard. This was an important event in the War of The Currents. Now AC could be safely supplied at everyone's doorstep.
+This made Edison's argument obsolete.
+
+Despite all his efforts to discredit AC, Edison failed. Westinghouse won the contract to supply electricity to the 1893 World’s Fair in Chicago—beating out rival General Electric, which was formed in 1892 by a merger involving Edison’s company—and the expo became a dazzling showcase for Tesla’s AC system. Westinghouse also received an important contract to construct the AC generators for a hydro-electric power plant at Niagara Falls; in 1896, the plant started delivering electricity all the way to Buffalo, New York, 26 miles away. Thus the first electric grid came into being. The achievement was regarded as the unofficial end to the War of the Currents, and AC became dominant in the electric power industry.
+
+The war pushed Westinghouse into bankruptcy. To save his friend, Tesla gave up all his perks that he had gained from his patents. As he grew
+old, the genius mind of Tesla took a toll on him and it drove him towards insanity. In his last days, Tesla lived in a hotel alone and without any cash. In 1943, Nikola Tesla died. Tesla was never given credit for his works and he ended penniless when he could have earned millions from his patents. Tesla's story is one of the msot tragic story in the history of science.
+
+The war of the currents changed the course of the history. We cannot imagine our lives without electricity. We today reap the benefits of the
+pioneering works of Edison and Tesla. Although today AC is the standard, DC is gaining importance with the advent of digital electronics. So it
+appears the War of the Currents may not be over yet. But instead of continuing in a heated AC vs. DC battle, it looks like the two currents will end up working parallel to each other in a sort of hybrid armistice.

blog_src/_posts/2017-12-28-Public-key-crypto.md

@@ -0,0 +1,101 @@
+---
+layout: post
+title: "How do websites communicate securely?"
+author_github: nishanthebbar2011
+date: 2017-12-28 23:33:44
+image: '/assets/img/'
+description: 'How cryptography ensures secure communication'
+tags:
+- SSL
+- Public Key Cryptography
+categories:
+- CompSoc
+github_username: 'nishanthebbar2011'
+comments: true
+---
+
+The inherent need for human beings has always been to communicate and share information,albeit selectively. For this purpose, the information is to be coded in such a way that it can be deciphered only by the recipient, regardless of whether the recipient is right next to the sender or on the other side of the world. __*The communication channel is assumed to be plagued with adversaries.*__.These adversaries have access to this coded information and are constantly trying to pry.So, the basic problem has always been to: 
+__*transfer secure information over such insecure channels.*__
+
+So, how DO you communicate when everyone is an adversary and nobody is trustworthy?
+The answer is simple.
+
+## Cryptography
+
+> "Cryptography is the art and science of making a crypto system that is capable of providing information security."
+
+The primary objective of cryptography is to provide basic security services like data integrity, confidentiality, user-authenticity and non-repudiation.
+
+
+## Crypto-systems
+
+Given below is a simple model of a crypto-system
+
+
+![Crypto-system](/blog/assets/img/Public-key-crypto/cryptosystem.jpg)
+
+
+
+There are two types of crypto-systems,based on how the encryption is carried out.
+
+### 1.Symmetric key encryption  
+
+Here, a single key is used for both encryption and decryption of the messages and such a key is established in advance by both the sender and the recipient.Thus,there has to exist "trust" between both sender and receiver, so as to not divulge the key.This was the most common method of encryption before the 1970's.
+
+
+![Symmetric key](/blog/assets/img/Public-key-crypto/symmetric_key_encryption.jpg)
+
+
+Suppose Alex wants to send a message to Carl using symmetric key encryption , then both of them will have to agree upon a key beforehand and use it to encrypt and decrypt the messages.
+
+### 2. Asymmetric key encryption/Public Key Cryptography 
+
+Here, two different keys are used for both encryption and decryption purposes and there exists some mathematical relation between the keys and thus decryption is possible.One of them is the private key and the other one is the public key.It is assumed that the private key is kept secret by a particular individual.
+
+An individual(recipient) makes one of his keys public.A sender can encrypt a message with the help of this public key and such an encrypted message is transmitted over the insecure channel. Only the recipient can decrypt this message with the help of his private key, since he alone possesses it. This is clearly a more elegant solution than symmetric key encryption, that relies on "trust". 
+
+
+![Asymmetric key ](/blog/assets/img/Public-key-crypto/asymmetric_key_encryption.jpg)
+
+
+
+The crux of this system is to ensure that it is computationally infeasible to deduce the private key from the public key and the encrypted message.Obviously, it is important to ensure that the public key actually belongs to the recipient. This is usually accomplished with the help of a trusted third party, that hands out digital certificates.These parties are called __*Certificate Authorities(CA's)*__.The public key is usually huge and is stored on such digital certificates whereas, the private key is stored on the system itself.
+
+Also with public-key encryption systems, authenticity of digital systems or documents can also be ascertained with the help of Digital signatures. The content is signed with an individual's private key , and since the public key is easily available, the identity of the user is easily verified.
+
+Suppose Alex sends a message(Using Carl's public key) and a digitally signed document to Carl, using a public-key encryption system, these are the advantages,in a nutshell:
+
+__1.__ It is possible to ascertain Alex's identity from his public key and digital signature on the document.
+
+__2.__ Only Alex could have signed the document,since he alone possesses the private key. Therefore it is not plausible for him to deny   sending it.
+
+__3.__ Only Carl possesses the private key for decrypting the message. He,alone can decrypt the message.
+
+__4.__ When the signature is verified by Carl, it checks that the contents of the document or message match what was in there when the signature was applied. Thus, integrity of the data is preserved.
+
+
+
+## The SSL Protocol
+
+
+ One of the major applications of public key cryptography is it's use in Secure Sockets Layer(SSL) protocol to ensure secure transactions   between web browsers and servers.The protocol uses a CA to identify one or both end of the transactions.This,in short, is how it works:
+
+__1.__ A browser requests a secure page (usually https://).
+
+__2.__ The web server sends its public key with its certificate.
+
+__3.__ The browser checks that the certificate was issued by a trusted party (usually a trusted root CA), that the certificate is still valid and that the certificate is related to the site contacted.
+
+__4.__ The browser then uses the public key, to encrypt a random symmetric encryption key and sends it to the server with the encrypted URL required as well as other encrypted http data.
+
+__5.__ The web server decrypts the symmetric encryption key using its private key and uses the symmetric key to decrypt the URL and htp data.
+
+__6.__ The web server sends back the requested html document and http data encrypted with the symmetric key.
+
+__7.__ The browser decrypts the http data and html document using the symmetric key and displays the information.
+
+Thus, as long as the CA is trustworthy, it is possible for the web browsers and servers to communicate securely and that is how all the information that is continuously exchanged on the internet stays safe and secure.
+
+
+
+