Computer hardware and software
 
Category: Computer hardware and software
The essay begins by defining what is meant by computer security and describing why it is important to constrain the definition to protection that can be meaningfully provided with a significant degree of assurance within computer systems. The theory of computer security — the reference monitor concept — is introduced next through an analogy with security concepts from the world of people and sensitive documents.           
1187 days ago
 
Controls are the elements of the User Interface with which the user can interact and control the application. Form is the first and main element of the user interface which acts as container for other elements. The basic controls are displayed as icons on the toolbox which is a part of the interface during the design time.
1187 days ago
 
To many people, the term electronic commerce (sometimes shortened to e-commerce) (Kalakota & Whinston 1999) means shopping in the part of the internet called the World Wide Web. However, e-commerce has a much broader scope and encompasses many more business activities other than just web shopping. Some people and businesses use the term electronic business (or e-business) when they are talking about e-commerce in this broader sense.
1187 days ago
 
Dynamic HTML is composed of a series of technologies which have helped to make Web pages interactive. The technologies comprising DHTML will be evolving. New technologies will be added from time to time. Fifteen years from now, of the technologies currently discussed here will become obsolete and new ones will have been added. Think of "dynamic" HTML as changing, evolving, improving over time as new technologies become available for Web developers and as more bandwidth becomes available to home users.
1187 days ago
 
Since version 3, Visual Basic has been the tool of choice for database programmers everywhere. First came DAO with version 3, RDO with version 4, and then the ability to build robust ActiveX components in version 5. With each successive version, Microsoft adds more functionality to make database programming easier for you. Visual Basic's powerful database feature set has continued to grow with version 6. New tools and technologies like ADO, OLE-DB, and the Microsoft Data Reporter vie for your attention. What does it all mean, what can it do for you, and most importantly, how do you quickly get up to speed
1187 days ago
 
• Used for analyzing network performance • In packet networks, events are random – Random packet arrivals – Random packet lengths • While at the physical layer we were concerned with bit-error-rate, at the network layer we care about delays – How long does a packet spend waiting in buffers ? – How large are the buffers ? • In circuit switched networks want to know call blocking probability – How many circuits do we need to limit the blocking probability?
1187 days ago
 
The British/Europeans refer to "operational research", the Americans to "operations research" - but both are often shortened to just "OR" (which is the term we will use). Another term which is used for this field is "management science" ("MS"). The Americans sometimes combine the terms OR and MS together and say "OR/MS" or "ORMS". Yet other terms sometimes used are "industrial engineering" ("IE"), "decision science" ("DS"), and “problem solving”. In recent years there has been a move towards a standardization upon a single term for the field, namely the term "OR".
1187 days ago
 
island’s connections (the bridges) to the other parts of the city. This observation led him to create an abstract discrete structure, later termed a graph. He identified each landmass with a node and each bridge with an edge connecting the two corresponding nodes in the graph. A walk in K¨onigsberg corresponds to a walk in the graph; crossing a bridge is represented by traversing an edge. Euler then noted that the number of edges adjacent to a node is essential.
1187 days ago
 
The assignment problem is a particular class of transportation linear programming problems with the supplies and demands equal to integers (often 1). Since all supplies, demands, and bounds on variables are integers, the assignment problem relies on an interesting property of transportation problems that the optimal solution will be entirely integers. In this lecture, the structure and formulation of assignment problem are discussed. Also, traveling salesman problem, which is a special type of assignment problem, is described.
1187 days ago
 
Game Theory is a misnomer for Multiperson Decision Theory, analyzing the decisionmaking process when there are more than one decision-makers where each agent’s payoff possibly depends on the actions taken by the other agents. Since an agent’s preferences on his actions depend on which actions the other parties take, his action depends on his beliefs about what the others do. Of course, what the others do depends on their beliefs about what each agent does. In this way, a player’s action, in principle, depends on the actions available to each agent, each agent’s preferences on the outcomes, each player’s beliefs about which actions are available to each player and how each player ranks the outcomes, and further his beliefs about each player’s beliefs, ad infinitum.
1187 days ago
 
• Given a set of 3-D objects and a view specification (camera), determine which lines or surfaces of the object are visible – you’ve already seen a VSD step…computing smallest non-negative t value along a ray – why might objects not be visible? occlusion vs. clipping – clipping is one object at a time while occlusion is global • Also called Hidden Surface Removal (HSR)
1187 days ago
 
• Using a computer as a rendering tool for the generation (from models) and manipulation of images is called computer graphics • More precisely: image synthesis Goals of Computer Graphics : • Generate synthetic images • Do it in a practical way and scientifically sound. • In real time? • And make it look easy
1187 days ago
 
Geometric primitive in computer graphics and CAD systems is used in various senses, with the common meaning of the simplest (i.e. 'atomic' or irreducible) geometric objects that the system can handle (draw, store). Sometimes the subroutines that draw the corresponding objects are called "geometric primitives" as well. The most "primitive" primitives are point and straight line segment, which were all that early vector graphics systems had.
1187 days ago
 
Transformation : • Moving points • (x,y) moves to (x+t, y+t) • Can be in any dimension – 2D – Image warps – 3D – 3D Graphics and Vision • Can also be considered as a movement to the coordinate axes
1187 days ago
 
Programmer specifies (x,y) values of end pixels Need algorithm to figure out which intermediate pixels are on line path Pixel (x,y) values constrained to integer values Actual computed intermediate line values may be floats Rounding may be required. E.g. computed point (10.48, 20.51) rounded to (10, 21) Rounded pixel value is off actual line path (jaggy!!) Sloped lines end up having jaggies Vertical, horizontal lines, no jaggies
1187 days ago
 
Software testing is as old as the hills in the history of digital computers. The testing of software is an important means of assessing the software to determine its quality. Since testing typically consumes 40~50% of development efforts, and consumes more effort for systems that require higher levels of reliability, it is a significant part of the software engineering. With the development of Fourth generation languages (4GL), which speeds up the implementation process, the proportion of time devoted to testing increased.
1187 days ago
 
 Choose high-level strategy for solving problem and building solution  Decide how to organize the system into subsystems  Identify concurrency / tasks  Allocate subsystems to HW and SW components
1187 days ago
 
A software requirements specification is a document which is used as a communication medium between the customer and the supplier. When the software requirement specification is completed and is accepted by all parties, the end of the requirements engineering phase has been reached. This is not to say, that after the acceptance phase, any of the requirements cannot be changed, but the changes must be tightly controlled. The software requirement specification should be edited by both the customer and the supplier, as initially neither has both the knowledge of what is required (the supplier) and what is feasible.
1187 days ago
 
Poor managment is the downfall of many software projects Delivered software was late, unreliable, cost several times the original estimates and often exhibited poor performance characteristics Software project management is different from other engineeering management product is intangible still no clear understanding of the software process or evaluation criteria most software projects are new and technically innovative Good management cannot guarantee project success, but bad management usually results in project failure
1187 days ago
 
In Software Engineering we study how to build and maintain software systems in a controlled, predictable way. In particular, good Software Engineering should give control over:
1187 days ago
 
• Multi-user, multi-tasking operating system. • Heritage goes back to Bell Laboratories over 20 years ago. • Unix has been ported to many platforms over the years.
1187 days ago
 
The von Neumann principle for the design and operation of computers requires that a program has to be primary memory resident to execute. Also, a user requires to revisit his programs often during its evolution. However, due to the fact that primary memory is volatile, a user needs to store his program in some non-volatile store. All computers provide a non-volatile secondary memory available as an online storage. Programs and files may be disk resident and downloaded whenever their execution is required. Therefore, some form of memory management is needed at both primary and secondary memory levels.
1187 days ago
 
Operating System (or shortly OS) primarily provides services for running applications on a computer system. The primary need for the OS arises from the fact that user needs to be provided with services and OS ought to facilitate the provisioning of these services. The central part of a computer system is a processing engine called CPU. A system should make it possible for a user’s application to use the processing unit. A user application would need to store information
1187 days ago
 
Mutual exclusion: only one process at a time can use a resource. Hold and wait: a process holding at least one resource is waiting to acquire additional resources held by other processes. No preemption: a resource can be released only voluntarily by the process holding it, after that process has completed its task. Circular wait: there exists a set {P0, P1, …, P0} of waiting processes such that P0 is waiting for a resource that is held by P1, P1 is waiting for a resource that is held by P2, …, Pn–1 is waiting for a resource that is held by Pn, and P0 is waiting for a resource that is held by P0.
1187 days ago
 
The transaction concept derives from contract law. In making a contract, two or more parties negotiate for a while and then make a deal. The deal is made binding by the joint signature of a document or by some other act (as simple as a handshake or nod). If the parties are rather suspicious of one another or just want to be safe, they appoint an intermediary (usually called an escrow officer to coordinate the commitment of the transaction.
1187 days ago
 
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