Code for Computer Science

 3D Display Methods 3D Projection Q. What is 3D Projection/Graphical Projection? It is a design technique used to display 3D objects on a 2D surface. Why we are using a 2D surface to display 3D objects? Because all graphics devices are 2D [like Monitor Screen]. When we want to draw 3D objects on a computer monitor. Convert the world coordinates into screen coordinates [i.e., project 3D objection on the 2D plane]. Q. What is the Projection? Process of representing 3D objects into 2D. [i.e., shadow of object]. Q. How an object is projected?  By projecting each of its points [create a map of points]. There are infinite points in Object. Take projection of only corner points of an object on a 2D plane than join these projected points by a straight line in the 2D plane. Q. What is a Parallel Projection? Projection of point in 3D space. Parallel Projection is a method for generating a view of a solid object. Project point on the object surface along parallel lines onto the display p...

 In the Cohen-Sutherland method, multiple intersections may be calculated along the path of a single line before an intersection on the clipping rectangle or line is completely rejected.  In Nicholl - Lee Nicholl Line Clipping, Extra intersection calculations are eliminated.  ADVANTAGE OF Nicholl - Lee Nicholl (NLN) Line Clipping 1.) The  number of clipping points is reduced to one, compared to other algorithms that may require two or more clipping.  2.)  Nicholl - Lee Nicholl (NLN) Line Clipping is FAST. Clipping algorithms for Circle, Curved boundary clipping regions are SLOWER because intersections calculations involve nonlinear curve equations.  3.)    Nicholl - Lee Nicholl (NLN) Line Clipping avoids multiple clipping of Line segments.  4.) As Compare to Cohen Sutherland and Liang-Barsy  Nicholl - Lee Nicholl Line Clipping performed fewer comparisons.    How Nicholl - Lee Nicholl Line Clipping works?  Nicholl...

 Particle swarm optimization (PSO) What is meant by PSO? PSO is a computational method that Optimizes a problem. It is a Population-based stochastic search algorithm. PSO is inspired by the Social Behavior of Birds flocking. n Particle Swarm Optimization the solution of the problem is represented using Particles. [Flocking birds are replaced with particles for algorithm simplicity]. Objective Function is used for the performance evaluation for each particle / agent in the current population. PSO solved problems by having a Population (called Swarms) of Candidate Solutions (Particles). Local and global optimal solutions are used to update particle position in each iteration. How PSO will optimize? By Improving a Candidate Solution. How PSO Solve Problems? PSO solved problems by having a Population (called Swarms) of Candidate Solutions (Particles). The population of Candidate Solutions (i.e., Particles). What is Search Space in PSO? It is the range in which the algorithm computes th...

 Viewing Pipeline: Viewing Transformation in several steps: 1. Modeling Coordinates 2. World Coordinate System 3. Clipping Window 4. Normalize - Normalized Coordinates  5. Device Coordinate  6. ViewPort 7. Clipping First, we construct the scene in the world coordinates using the output primitives. Next, obtain a particular orientation for the window, we can set up a 2D viewing coordinate plane and define windows in the viewing coordinate system. The viewing coordinate reference frame is used to provide a method for setting up arbitrary orientations for a rectangular window.  Once the viewing reference frame is established. we can transform description in the world coordinate to viewing coordinates. After that define a viewport in normalized coordinates ( in the range from 0 to 1). 2D Viewing Pipeline can be achieved by the following steps:  1. Construct world coordinate scene using modeling coordinate transformation.  2. convert world coordinates to viewin...

1. Account Hijacking  Attackers can access user accounts remotely. Attackers can access data stored on the cloud. Methods of Hijacking: Reused Password and Scripting Bugs [in April 2010 Amazon faced crossed-site scripting bug].  2. Insider threat An Attack from inside your organization [Business Partnership]. Employees can use their authorized access to an organization’s cloud-based services. Employees can misuse or access information such as  Customer accounts, Financial forms, and other sensitive information. 3. Phishing and social engineering attacks Once login information or other confidential information is available. A malicious user can log into a system easily as the system is accessible from anywhere. 4. Malware injection Malware Injection means Code or Scripts embedded into cloud services.  Malicious code can be injected into cloud services. Injected code is viewed as part of the software or service that is running within the cloud servers themselves. ...

  Metaheuristic  means a High-level problem-independent algorithmic framework that is developed for the optimization algorithm. Metaheuristic algorithms  find the best solution out of all possible solutions of an optimization. I discussed some Meta-heuristic algorithm like: Grey Wolf Optimization (GWO) Algorithm:  GWO is a metaheuristic proposed by Mirjaliali Mohammad and Lewis, 2014. GWO is inspired by the social hierarchy and the hunting technique of Grey Wolves Bat Algorithm:  The  Bat algorithm  is a metaheuristic algorithm for global optimization. It was inspired by the echolocation behavior of microbats. Cuckoo Search Algorithm: Cuckoo Search is a n ature-inspired  algorithm , based on the brood reproductive strategy of cuckoo birds to increase their population. Meta-heuristic Algorithms

Cloud Computing includes Several elements like: Clients Datacenters Distributed servers Each component has a Purpose and plays a specific role in delivering a functional Cloud-based application.  1. Clients: C lients are typically computers. Clients are devices that end-users interact with to manage their information on Cloud.  For example Laptops, Mobiles Phones,  Tablets  Note: because of their mobility they are big drivers for Cloud computing.  2. Datacenter means the Collection of Servers. W here the application to which you subscribe is housed. A growing trend in the IT world is VIRTUALIZING servers. Multiple Virtual servers running on one physical server. 3. Distributed servers mean Large networks have Multiple servers. Servers are in geographically disparate locations. It provides more flexibility and security to the service providers.  For example, Amazon has its own Cloud solution in servers all over the world....

  Monoalphabetic Substitution Cipher, also known as a simple substitution cipher, relies (depends) on a fixed replacement structure. That is substitution is fixed for each letter of the alphabet.  A simple example is where each letter is encrypted as the next letter in the alphabet: "a simple message" becomes "B TJNQMF NFTTBHF". Each letter can be encrypted to any symbol [&,%,?,/,*,{},@,~,+,-] not just another letter. 1.) Additive Cipher The Simplest Monoalphabetic cipher is an Additive cipher. This cipher is sometimes called Shift Cipher. When the Cipher is Additive, the Plain Text, Cipher Text and key are integers in Z(26). For Encryption: C = (p + k) mod 26 For Decryption: P = (c - k) mod 26 Where, C = Cipher Text                   P = Plain Text                   k = Key  The secret key between Alice and Bob is also an integer value. The encryption Algorithm adds the key to t...