Environmental management is not, as the phrase could suggest, the management of the environment as such, but rather the management of interaction by the modern human societies with, and impact upon the environment. The three main issues that affect managers are those involving politics (networking), programs (projects), and resources (money, facilities, etc.). The need for environmental management can be viewed from a variety of perspectives. A more common philosophy and impetus behind environmental management is the concept of carrying capacity. Simply put, carrying capacity refers to the maximum number of organisms a particular resource can sustain. The concept of carrying capacity, whilst understood by many cultures over history, has its roots in Malthusian theory. Environmental management is therefore not the conservation of the environment solely for the environment's sake, but rather the conservation of the environment for humankind's sake.

Environmental management involves the management of all components of the bio-physical environment, both living (biotic) and non-living (abiotic). This is due to the interconnected and network of relationships amongst all living species and their habitats. The environment also involves the relationships of the human environment, such as the social, cultural and economic environment with the bio-physical environment.

As with all management functions, effective management tools, standards and systems are required. An 'environmental management standard or system or protocol attempts to reduce environmental impact as measured by some objective criteria. The ISO 14001 standard is the most widely used standard for environmental risk management and is closely aligned to the European Eco-Management and Audit Scheme (EMAS). As a common auditing standard, the ISO 19011 standard explains how to combine this with quality management.

Other environmental management systems (EMS) tend to be based on the ISO 14001 standard and many extend it in various ways:

The Green Dragon Environmental Management Standard is a five level EMS designed for smaller organisations for whom ISO 14001 may be too onerous and for larger organisations who wish to implement ISO 14001 in a more manageable step-by-step approach

BS 8555 is a phased standard that can help smaller companies move to ISO 14001 in six manageable steps

The Natural Step focuses on basic sustainability criteria and helps focus engineering on reducing use of materials or energy use that is unsustainable in the long term

Natural Capitalism advises using accounting reform and a general biomimicry and industrial ecology approach to do the same thing

US Environmental Protection Agency has many further terms and standards that it defines as appropriate to large-scale EMS.[citation needed]

The UN and World Bank has encouraged adopting a "natural capital" measurement and management framework.[citation needed]

The European Union Eco-Management and Audit Scheme (EMAS)

Other strategies exist that rely on making simple distinctions rather than building top-down management "systems" using performance audits and full cost accounting. For instance, Ecological Intelligent Design divides products into consumables, service products or durables and unsaleables - toxic products that no one should buy, or in many cases, do not realize they are buying. By eliminating the unsaleables from the comprehensive outcome of any purchase, better environmental management is achieved without "systems".

Recent successful cases have put forward the notion of "Integrated Management". It shares a wider approach and stresses out the importance of interdisciplinary assessment. It is an interesting notion that might not be adaptable to all cases.

"Today's businesses must comply with many Federal, State and local environmental laws, rules, and regulations. It's vital to safeguard your company against compliance short-cuts. This approach leaves you vulnerable to violations of the law, in addition to missing important environmental liabilities."

In a very broad sense, the term information system is frequently used to refer to the interaction between people, processes, data and technology. In this sense, the term is used to refer not only to the information and communication technology (ICT) an organization uses, but also to the way in which people interact with this technology in support of business processes.

Some make a clear distinction between information systems, ICT and business processes. Information systems are distinct from information technology in that an information system is typically seen as having an ICT component. Information systems are also different from business processes. Information systems help to control the performance of business processes.

Alter argues for an information system as a special type of work system. A work system is a system in which humans and/or machines perform work using resources (including ICT) to produce specific products and/or services for customers. An information system is a work system whose activities are devoted to processing (capturing, transmitting, storing, retrieving, manipulating and displaying)information.

Part of the difficulty in defining the term information system is due to vagueness in the definition of related terms such as system and information. Beynon-Davies argues for a clearer terminology based in systemics and semiotics. He defines an information system as an example of a system concerned with the manipulation of signs. An information system is a type of socio-technical system. An information system is a mediating construct between actions and technology.

As such, information systems inter-relate with data systems on the one hand and activity systems on the other. An information system is a form of communication system in which data represent and are processed as a form of social memory. An information system can also be considered a semi-formal language which supports human decision making and action.

Information systems are the primary focus of study for the information systems discipline and for organisational informatics.

The term information systems is used to refer to at least three things: an academic field, an area of professional work or as the plural of the term information system.

In a broad sense, the term Information Systems (IS) refers to the interaction between processes, and technology. This interaction can occur within or across organizational boundaries. An information system is not only the technology an organization uses, but also the way in which the organizations interact with the technology and the way in which the technology works with the organization’s business processes. Information systems are distinct from information technology in that an information system has an information technology component that interacts with the processes components.

Overview

The Information System consists of four parts which include: procedures, software, hardware, and information or data, which are essentially the same. There are various types of information systems, for example: transaction processing systems, office systems, decision support systems, knowledge management systems, database management systems, and office information systems. Critical to most information systems are information technologies, which are typically designed to enable humans to perform tasks for which the human brain is not well suited, such as: handling large amounts of information, performing complex calculations, and controlling many simultaneous processes.

Information technologies are a very important and malleable resource available to executives. Many companies have created a position of Chief Information Officer (CIO) that sits on the executive board with the Chief Executive Officer (CEO), Chief Financial Officer (CFO), Chief Operating Officer (COO) and Chief Technical Officer (CTO).The CTO may also serve as CIO, and vice versa. The Chief Information Security Officer (CISO), who focuses on information security within an organization, normally reports to the CIO.

In computer security, an information system is described by the following components:

Repositories, which hold data permanently or temporarily, such as buffers, RAM, hard disks, cache, etc. Often data stored in repositories is managed through a database management system.

Interfaces, which support the interaction between humans and computers, such as keyboards, speakers, scanners, printers, etc.

Channels, which connect repositories, such as routers, cables, etc..

Types of information systems

The 'classic' view of Information systems found in the textbooks[3] of the 1980s was of a pyramid of systems that reflected the hierarchy of the organization, usually Transaction processing systems at the bottom of the pyramid, followed by Management information systems, Decision support systems and ending with Executive information systems at the top.

However, as new information technologies have been developed, new categories of information systems have emerged, some of which no longer fit easily into the original pyramid model. Some examples of such systems are:

Data warehouses

Enterprise resource planning

Enterprise systems

Expert systems

Global information system

Office Automation

Information systems careers

Information Systems have a number of different areas of work:

Information systems strategy

Information systems management

Information systems development

Information systems security

Information systems iteration

There are a wide variety of career paths in the information systems discipline. "Workers with specialized technical knowledge and strong communications skills will have the best prospects. With management skills and an understanding of business practices and principles will have excellent opportunities, as companies are increasingly looking to technology to drive their revenue."

Information systems development

Information technology departments in larger organizations tend to strongly influence information technology development, use, and application in the organizations, which may be a business or corporation. A series of methodologies and processes can be used in order to develop and use an information system. Many developers have turned and used a more engineering approach such as the System Development Life Cycle (SDLC) which is a systematic procedure of developing an information system through stages that occur in sequence. An Information system can be developed in house (within the organization) or outsourced. This can be accomplished by outsourcing certain components or the entire system. A specific case is the geographical distribution of the development team (Offshoring, Global Information System).

A computer based information system, following a definition of Langefors, is:

a technologically implemented medium for recording, storing, and disseminating linguistic expressions,

as well as for drawing conclusions from such expressions.

which can be formulated as a generalized information systems design mathematical program

Geographic Information Systems, Land Information systems and Disaster Information Systems are also some of the emerging information systems but they can be broadly considered as Spatial Information Systems. System development is done in stages which include:

Problem recognition and specification

Information gathering

Requirements specification for the new system

System design

System construction

System implementation

Review and maintenance

Information systems development methodology

Information systems development methodology or ISDM is a tool kit of ideas, approaches, techniques and tools which system analysts use to help them translate organisational needs into appropriate Information Systems;

An ISDM is:-

'....recommended collection of philosophies, phases, procedures, rules, techniques, tools, documentation, management, and training for developers of Information Systems”. (Avison and Fitzgerald, 1988)

Information systems research

Information systems research is generally concerned with the study of the effects of information systems on the behavior of individuals, groups, and organizations. Notable publication outlets for information systems research are the journals Management Information Systems Quarterly, Information Systems Research, Journal of the Association for Information Systems, and Communications of the Association for Information Systems.

Since information systems is an applied field, industry practitioners expect information systems research to generate findings that are immediately applicable in practice. However, that is not always the case. Often information systems researchers explore behavioral issues in much more depth than practitioners would expect them to do. This may render information systems research results difficult to understand, and has led to criticism.

To study an information system itself, rather than its effects, information systems models are used, such as EATPUT.

Infosys Technologies Limited (BSE: 500209, NASDAQ: INFY) is a multinational information technology services company headquartered in Bangalore, India. It is one of India's largest IT companies with 103,905 professionals (including subsidiaries) as of Jun 30, 2009.It has offices in 22 countries and development centers in India, China, Australia, UK, Canada and Japan.
History
Infosys was founded on July 2, 1981 in Pune by N. R. Narayana Murthy and six others: Nandan Nilekani, N. S. Raghavan, Kris Gopalakrishnan, S. D. Shibulal, K. Dinesh and Ashok Arora,[4] with N. S. Raghavan officially being the first employee of the company. Murthy started the company by borrowing INR 10,000 from his wife Sudha Murthy. The company was incorporated as "Infosys Consultants Pvt Ltd.", with Raghavan's house in Model Colony, north-central Pune as the registered office.

In 1982, Infosys opened an office in Bangalore which soon became its headquarters.

Infosys went public in 1993. Interestingly, Infosys IPO was undersubscribed but it was "bailed out" by US investment banker Morgan Stanley which picked up 13% of equity at the offer price of Rs. 95 per share. The share price surged to Rs. 8,100 by 1999 making it the costliest share on the market at the time.[6] At that time, Infosys was among the 20 biggest companies by market capitalization on the Nasdaq well ahead of Adobe Systems, Novell and Lycos.

According to Forbes magazine, since listing on the Bombay Stock Exchange till the year 2000, Infosys' sales and earnings compounded at more than 70% a year.In the year 2000, President of the United States Bill Clinton complimented India on its achievements in high technology areas citing the example of Infosys.

In 2001, it was rated Best Employer in India by Business Today. Infosys won the Global MAKE (Most Admired Knowledge Enterprises) award, for the years 2003, 2004 and 2005, being the only Indian company to win this award and is inducted into the Global Hall of Fame for the same.

Infosys was rated best employer to work for in 2000, 2001, and 2002 by Hewitt Associates. In 2007, Infosys received over 1.3 million applications and hired fewer than 3% of applicants.

BusinessWeek reported that Infosys, along with Wipro and Tata accounted for nearly 80% of the [H-1B] visa petitions approved in 2007 for the top 10 participants in the program.

In April 2009, Forbes rated Infosys among the 5 best performing companies in the software and services sector in the world.

In 2009, Infosys was considered one of the BusinessWeek's 50 Most Innovative Companies.

From December 2008 till April 2009, Infosys fired over 2500 employees for poor performance. The company has been hit hard by lower income from a crisis hit European and North American market. On April 15, 2009 Infosys reported its first ever sequential fall in its revenue in a decade during the March 2009 quarter.

Timeline
1981: Infosys is established by N. R. Narayana Murthy and six engineers in Pune, India, with an initial capital of US$ 250. Signs up its first client, Data Basics Corporation, in New York
1983: Moved its headquarters to Bangalore, the capital of Karnataka
1987: Opens first international office in Boston, US
1992: Opened its first overseas sales office in Boston.
1993: Became a public limited company in India with an initial public offering of Rs. 13 crores.
1996: First office in Europe in Milton Keynes, UK
1997: Office in Toronto, Canada
1999: First Indian company to be listed on Nasdaq on March 11.[17]
1999: Attained a SEI-CMM Level 5 ranking
2000: Opened offices in France and Hong Kong
2001: Opened offices in United Arab Emirates and Argentina
2002: Opened new offices in Netherlands, Singapore and Switzerland.
2002: Business World named Infosys "India's Most Respected Company".[18]
2002: Started Progeon, its BPO (business process outsourcing) subsidiary[19]
2003: Acquired 100% equity of Expert Information Services Pty Limited, Australia (Expert) and changed the name to Infosys Australia Pty Limited.
2004: Set up Infosys Consulting Inc., U.S. consulting subsidiary in California, U.S.
2006: Became the first Indian company to ring the NASDAQ Stock Market Opening Bell
2006: August 20, N. R. Narayana Murthy retired from his position as the executive chairman. [20]
2006: Acquired the 23% stake Citibank had in its BPO offshoot Progeon, making it a wholly owned subsidiary of Infosys and changed the name to Infosys BPO Ltd.[21]
2006: December, became the first Indian company to make it to Nasdaq-100[22]
2007: April 13, Nandan Nilekani stepped down as CEO and made way for Kris Gopalakrishnan to occupy his chair effective June 2007
2007: July 25, Infosys bags multi-million dollar outsourcing contract with Royal Philips Electronics in the area Finance & Accounting services strengthening its European operations.
2007: September, Infosys establishes a wholly-owned Latin American subsidiary, Infosys Technologies S. de R. L. de C. V., and opens its first software development center in Latin America in the city of Monterrey, Mexico.
2008: Agreed to buy British consultancy Axon Group for 407 million pounds ($753 million), but HCL Technologies outbid Infosys for 441 million pounds[23]. However, Infosys gained Rs. 180 million from the failed Axon bid.[24]
During the 14-year period from its IPO in 1993 to 2007, the price of an Infosys share increased three thousandfold. This excludes the dividends that the company has paid out over that duration.

Key industries

Infosys serves various industries through its Industrial Business Units (IBU), such as:

Banking & Capital Markets (BCM)
Communications, Media and Entertainment (CME)
Energy, Utilities and Services (EUS)
Insurance, Healthcare and Life Sciences (IHL)
Manufacturing (MFG)
Retail, Consumer Product Goods and Logistics (RETL)
New Markets and Services (NMS) : Non US and Non European markets, SaaS, Learning Services
India Business Unit (IND)
In addition to these, there are Horizontal Business Units (HBUs)

Consulting (CS)
Enterprise Solutions (ES): ERP, CRM, HCM, SCM, BI/DW, BPM-EAI
Infrastructure Management Services (IMS)
Product Engineering and Validation Services (PEVS)
Systems Integration (SI)
Finacle : Core Banking Product

Initiatives
In 1996, Infosys created the Infosys Foundation in the state of Karnataka, operating in the areas of health care, social rehabilitation and rural uplift, education, arts and culture. Since then, this foundation has spread to the Indian states of Tamil Nadu, Andhra Pradesh, Maharashtra, Kerala, Orissa and Punjab. The Infosys Foundation is headed by Mrs. Sudha Murthy, wife of Chairman Narayana Murthy.

Since 2004, Infosys has embarked on a series of initiatives to consolidate and formalize its academic relationships worldwide under the umbrella of a program called AcE - Academic Entente. Through case study writing, participation in academic conferences and university events, research collaborations, hosting study trips to Infosys Development Centers and running the InStep Global Internship Program, the company communicates with important stakeholders in the academia.

Infosys' Global Internship Program, known as InStep, is one of the key components of the Academic Entente initiative. It offers live projects to interns from the universities around the world. InStep recruits undergraduate, graduate and PhD students from business, technology, and liberal arts universities to take part in an 8 to 24 week internship at one of Infosys' global offices. InStep interns are also provided career opportunities with Infosys.

In 1997 Infosys started the "Catch them Young Programme", to expose the urban youth to the world of Information Technology by conducting a summer vacation programme. The programme is aimed at developing an interest and understanding of computer science and information technology. This programme is targeted at students in Grade IX level.[25]

In 2002, the Wharton Business School of the University of Pennsylvania and Infosys started the Wharton Infosys Business Transformation Award. This technology award recognizes enterprises and individuals who have transformed their businesses and the society leveraging information technology. Past winners include Samsung, Amazon.com, Capital One, RBS and ING Direct.

Infosys also has the largest training center for a private sector organization in Asia. The training center is located in Mysore, Karnataka. It currently accommodates 4,500 trainees each year. In 2009 a new training center has been opened which accommodates 10,000 trainee software professionals. This new center is also located in Mysore.

In 2008, Infosys along with National Institute of Advanced Studies created 'Infosys Mathematics Prize' for excellence in Mathematics research.

HP Pavilion is a line of personal computers produced by Hewlett-Packard and introduced in 1995. The name is applied to both desktops and laptops for the Home and Home Office product range.



When HP merged with Compaq in 2002, it took over Compaq's existing naming rights agreement. As a result, HP sells both HP and Compaq-branded machines. Computers can be ordered either directly from the factory or over the phone, and can be customized through choosing desired specifications. This is known as a CTO (formerly BTO) option.

HP Pavilion is a line of personal computers produced by Hewlett-Packard and introduced in 1995. The name is applied to both desktops and laptops for the Home and Home Office product range.




When HP merged with Compaq in 2002, it took over Compaq's existing naming rights agreement. As a result, HP sells both HP and Compaq-branded machines. Computers can be ordered either directly from the factory or over the phone, and can be customized through choosing desired specifications. This is known as a CTO (formerly BTO) option.

History


.In 1995, The HP Pavilion PC marks the company's highly successful introduction into the home-computing market.
Dave Packard publishes The HP Way, a book that chronicles the rise of HP and gives insight into the business practices, culture and management style that helped make it a success. The industry's first low-cost, high-speed small infrared transceiver allows wireless "point and shoot" data exchange in a wide range of portable computing applications such as phones, computers, printers, cash registers, ATMs, digital cameras and more.[1]




[edit] The First HP Pavilion PC

The HP pavilion 5030 was HP's first multimedia PC designed specifically for the home market, and it went on to become a market leader in consumer PCs. It featured a quad-speed CD-ROM drive, Altec Lansing speakers, software for online service access and Microsoft Windows 95. This entry-level model features an 75 MHz Intel Pentium processor, 8 MB RAM and an 850 MB hard drive.[2]



[edit] Notebooks

HP offers 8 notebook lines under the HP Pavilion name, 2 under HDX, 4 under HP Mini, 1 under TouchSmart, 2 under G series, and 1 under Compaq Presario. These are customizable in the US only. A wide variety of different models with different setups are offered in Canada and elsewhere.



[edit] Current Notebook Models

18.4 inch : HDX18t

17.3 inch : dv7t

17.0 inch : G70t

16.0 inch : HDX16t / dv6t / dv6z / dv6zae (Artist Edition 2) / G60t

15.6 inch : Compaq CQ60

15.4 inch : dv5tse

14.1 inch : dv4tse / dv4t

13.3 inch : dv3t / Voodoo Envy 133

12.1 inch : TouchSmart tx2z / HP Pavilion dv2z

10.1 inch : HP Mini 110 Mi / HP Mini 110 XP / / Mini 1000 Vivienne Tam

[edit] Previous Notebook Models

20.1 inch : HDX9000

17.0 inch : dv7z / dv9000 / dv8000 / zd8000 / zd7000

15.4 inch : dv5 / dv6500tse (Special Edition) / dv6000 / dv5000 / dv4000 / zv6000 / zv5000 / zx5000 / ze5000 / ze4000 / zt3000

15.0 inch : ze2000 / ze1000 / zt1000

14.1 inch : dv4z / dv2800tae (Artist Edition) / dv2500tse (Special Edition) / dv2000 / dv1000

13.3 inch : dv3z / dv3500t

12.1 inch : tx1000z tablet PC / tx2000z Tablet PC / tx2500z Tablet PC

10.1 inch : Mini 1000 Mi / Mini 1000 XP / Mini 1000 Mobile Broadband Wireless

8.9 inch : Mini 1000 Mi / Mini 1000 XP / Mini 1000 Mobile Broadband Wireless

[edit] Model Number Suffixes

The two or three letter suffix on the model number indicates special information like country or language (dv----xx). The following chart describes each suffix.



t : Intel Processor

z : AMD Processor

ae : Artist Edition (Artist Edition Imprint)

bw : Broadband Wireless Series

se : Special Edition ("Intensity" dv4tse, "Renewal" dv5tse, Special Edition Imprint)

The following sufixes corresponds to the region the notebook is sold.



us : United States

ca : Canada

la : Latin America

ea / ee / (e + a letter) : Europe / Middle East

au / ax : Asia / Australia - AMD Processor (AU = AMD + UMA, AX = AMD + Discrete *UMA and Discrete refers to graphics *)

tu / tx : Asia / Australia - Intel Processor (TU = Intel + UMA, TX = Intel + Discrete)

Other suffixes include nr, cl, and wm.



nr : No Region

cl : Club Model (These models are available only through some clubs like Costco and Sam's Club)

wm : Walmart Model

br : Brazil

ap : Asia Pacific

The HP Pavilion HDX is only sold with Intel Processors, but it doesn't end with the suffix "t". It has no suffix.



The HP Pavilion tx tablet PC series are currently sold with AMD Processors only, but they still end with the suffix "z".



Take Action. Make Art


HP and MTV held a contest for young people around the world to help design a special edition HP notebook. The theme: the cause that is most personal to you. It all starts with your personal view. Imagine that your design is a positive thought, a belief, a message you want to tell the world. Your take on how to make our planet or your community a better place.



The contest went from September 5, 2007 to October 17, 2007 and over 8,500 designs from 112 countries were submitted.



"Asian Odyssey" the personal design of 20-year old João Oliveira of Porto, Portugal, was chosen as the winner of the "Take Action. Make Art" global notebook-design competition. The winning design is featured on the HP dv2800tae Series Notebook. There were 4 other top regional designs and they were featured as exclusive laptop skin covers at skinit.com. The regional finalists are Jeremy Kiraly of Queensland, Australia, Marco Feola of Rome, Italy, Eduardo Arevalo Lopez of Bogota, Colombia and Charles Williams of Ottawa, Canada.



HP Engine Room

“Engine Room” is a series of challenges created by HP and partners in which young artists from around the world can showcase their creativity and bring art to life with technology. HP held another contest to design a special edition notebook.



Artists from 94 countries submitted nearly 17,000 designs with the hopes that their art would be displayed on an HP notebook PC. More than 62,000 votes were received from 159 countries.



Hisako Sakihama, a 27-year-old designer from Japan was the winner of the “Engine Room” Notebook Design Contest. The regional finalists include Rodrigo Daniel Diaz from Argentina, Carlos Alonso Zebenzuy from Spain, Abhishek Goswami from India, and Stacy Pezzola from the United States. The regional finalists will have their art transformed into notebook attachable “skins” from SkinIt, which will be made available to consumers around the world.



 Criticisms

Some models of Pavilion laptop have been criticized as having faulty power jacks, which separate from the motherboard under normal use.

Some models have ongoing problems with wireless connectivity

Recently the dv9000 series notebooks have a Hinge problem, where the left side of the screen will snap off when opening. Some say this is due to a design flaw, but has yet to be publicly addressed. a website has been created for this problem, it is called http://www.notebookhingecrack.com/

Users with HP Pavilion laptops report having their volume button jumping erratically and clicking and the sounds moving up and down on its own accord, this can be fixed by uninstalling HP's QuickTouch on-screen display [9]

an amplifier or simply amp, is any device that changes, usually increases, the amplitude of a signal. The relationship of the input to the output of an amplifier—usually expressed as a function of the input frequency—is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain.

In popular use, the term usually describes an electronic amplifier, in which the input "signal" is usually voltage or current. In audio applications, amplifiers operate loudspeakers used in PA systems to make the human voice louder or play recorded music. Amplifiers may be classified according to the input (source) they are designed to amplify (such as a guitar amplifier, to perform with an electric guitar), the device they are intended to drive (such as a headphone amplifier), the frequency range of the signals (Audio, IF, RF, and VHF amplifiers, for example), whether they invert the signal (inverting amplifiers and non-inverting amplifiers), or the type of device used in the amplification (valve or tube amplifiers, FET amplifiers, etc.).

A related device that emphasizes conversion of signals of one type to another (for example, a light signal in photons to a DC signal in amperes) is a transducer, a transformer, or a sensor. However, none of these amplify power.

Figures of merit
The quality of an amplifier can be characterized by a number of specifications, listed below.

Gain
The gain of an amplifier is the ratio of output to input power or amplitude, and is usually measured in decibels. (When measured in decibels it is logarithmically related to the power ratio: G(dB)=10 log(Pout /(Pin)). RF amplifiers are often specified in terms of the maximum power gain obtainable, while the voltage gain of audio amplifiers and instrumentation amplifiers will be more often specified (since the amplifier's input impedance will often be much higher than the source impedance, and the load impedance higher than the amplifier's output impedance).

Example: an audio amplifier with a gain given as 20dB will have a voltage gain of ten (but a power gain of 100 would only occur in the unlikely event the input and output impedances were identical).

Bandwidth
The bandwidth (BW) of an amplifier is the range of frequencies for which the amplifier gives "satisfactory performance". The "satisfactory performance" may be different for different applications. However, a common and well-accepted metric are the half power points (i.e. frequency where the power goes down by half its peak value) on the power vs. frequency curve. Therefore bandwidth can be defined as the difference between the lower and upper half power points. This is therefore also known as the −3 dB bandwidth. Bandwidths (otherwise called "frequency responses") for other response tolerances are sometimes quoted (−1 dB, −6 dB etc.) or "plus or minus 1dB" (roughly the sound level difference people usually can detect).

A full-range audio amplifier will be essentially flat between 20 Hz to about 20 kHz (the range of normal human hearing). In minimalist amplifier design, the amp's usable frequency response needs to extend considerably beyond this (one or more octaves either side) and typically a good minimalist amplifier will have −3 dB points < 10 and > 65 kHz. Professional touring amplifiers often have input and/or output filtering to sharply limit frequency response beyond 20 Hz-20 kHz; too much of the amplifier's potential output power would otherwise be wasted on infrasonic and ultrasonic frequencies, and the danger of AM radio interference would increase. Modern switching amplifiers need steep low pass filtering at the output to get rid of high frequency switching noise and harmonics.

Efficiency
Efficiency is a measure of how much of the input power is usefully applied to the amplifier's output. Class A amplifiers are very inefficient, in the range of 10–20% with a max efficiency of 25%. Class B amplifiers have a very high efficiency but are impractical because of high levels of distortion (See: Crossover distortion). In practical design, the result of a tradeoff is the class AB design. Modern Class AB amps are commonly between 35–55% efficient with a theoretical maximum of 78.5%. Commercially available Class D switching amplifiers have reported efficiencies as high as 90%. Amplifiers of Class C-F are usually known to be very high efficiency amplifiers. The efficiency of the amplifier limits the amount of total power output that is usefully available. Note that more efficient amplifiers run much cooler, and often do not need any cooling fans even in multi-kilowatt designs. The reason for this is that the loss of efficiency produces heat as a by-product of the energy lost during the conversion of power. In more efficient amplifiers there is less loss of energy so in turn less heat.

In RF Power Amplifiers, such as cellular base stations and broadcast transmitters, specialist design techniques are used to improve efficiency. Doherty designs, which use a second transistor, can lift efficiency from the typical 15% up to 30-35% in a narrow bandwidth. Envelope Tracking designs are able to achieve efficiencies of up to 60%, by modulating the supply voltage to the amplifier in line with the envelope of the signal.

Linearity
An ideal amplifier would be a totally linear device, but real amplifiers are only linear within certain practical limits. When the signal drive to the amplifier is increased, the output also increases until a point is reached where some part of the amplifier becomes saturated and cannot produce any more output; this is called clipping, and results in distortion.

Some amplifiers are designed to handle this in a controlled way which causes a reduction in gain to take place instead of excessive distortion; the result is a compression effect, which (if the amplifier is an audio amplifier) will sound much less unpleasant to the ear. For these amplifiers, the 1 dB compression point is defined as the input power (or output power) where the gain is 1 dB less than the small signal gain.

Linearization is an emergent field, and there are many techniques, such as feedforward, predistortion, postdistortion, EER, LINC, CALLUM, cartesian feedback, etc., in order to avoid the undesired effects of the non-linearities.

Noise
This is a measure of how much noise is introduced in the amplification process. Noise is an undesirable but inevitable product of the electronic devices and components. The metric for noise performance of a circuit is Noise Factor. Noise Factor is the ratio of input signal to that of the output signal.

Output dynamic range
Output dynamic range is the range, usually given in dB, between the smallest and largest useful output levels. The lowest useful level is limited by output noise, while the largest is limited most often by distortion. The ratio of these two is quoted as the amplifier dynamic range. More precisely, if S = maximal allowed signal power and N = noise power, the dynamic range DR is DR = (S + N ) /N.[1]

Slew rate
Slew rate is the maximum rate of change of output variable, usually quoted in volts per second (or microsecond). Many amplifiers are ultimately slew rate limited (typically by the impedance of a drive current having to overcome capacitive effects at some point in the circuit), which may limit the full power bandwidth to frequencies well below the amplifier's small-signal frequency response.

Rise time
The rise time, tr, of an amplifier is the time taken for the output to change from 10% to 90% of its final level when driven by a step input. For a Gaussian response system (or a simple RC roll off), the rise time is approximated by:

tr * BW = 0.35, where tr is rise time in seconds and BW is bandwidth in Hz.

Settling time and ringing
Time taken for output to settle to within a certain percentage of the final value (say 0.1%). This is called the settle time, and is usually specified for oscilloscope vertical amplifiers and high accuracy measurement systems. Ringing refers to an output that cycles above and below its final value, leading to a delay in reaching final value quantified by the settling time above.

Overshoot
In response to a step input, the overshoot is the amount the output exceeds its final, steady-state value.

Stability factor
Stability is a major concern in RF and microwave amplifiers. The degree of an amplifier's stability can be quantified by a so-called stability factor. There are several different stability factors, such as the Stern stability factor and the Linvil stability factor, which specify a condition that must be met for the absolute stability of an amplifier in terms of its two-port parameters.

Electronic amplifiers
Main article: Electronic amplifier
There are many types of electronic amplifiers, commonly used in radio and television transmitters and receivers, high-fidelity ("hi-fi") stereo equipment, microcomputers and other electronic digital equipment, and guitar and other instrument amplifiers. Critical components include active devices, such as vacuum tubes or transistors. A brief introduction to the many types of electronic amplifier follows.

Power amplifier
The term "power amplifier" is a relative term with respect to the amount of power delivered to the load and/or sourced by the supply circuit. In general a power amplifier is designated as the last amplifier in a transmission chain (the output stage) and is the amplifier stage that typically requires most attention to power efficiency. Efficiency considerations lead to various classes of power amplifier: see power amplifier classes.

Operational amplifiers (op-amps)
An operational amplifier is an amplifier circuit with very high open loop gain and differential inputs which employs external feedback for control of its transfer function or gain. Although the term is today commonly applied to integrated circuits, the original operational amplifier design was implemented with valves.

Fully differential amplifiers (FDA)
A fully differential amplifier is a solid state integrated circuit amplifier which employs external feedback for control of its transfer function or gain. It is similar to the operational amplifier but it also has differential output pins.

[edit] Video amplifiers
These deal with video signals and have varying bandwidths depending on whether the video signal is for SDTV, EDTV, HDTV 720p or 1080i/p etc.. The specification of the bandwidth itself depends on what kind of filter is used and which point (-1 dB or -3 dB for example) the bandwidth is measured. Certain requirements for step response and overshoot are necessary in order for acceptable TV images to be presented.

Oscilloscope vertical amplifiers
These are used to deal with video signals to drive an oscilloscope display tube and can have bandwidths of about 500 MHz. The specifications on step response, rise time, overshoot and aberrations can make the design of these amplifiers extremely difficult. One of the pioneers in high bandwidth vertical amplifiers was the Tektronix company.

Distributed amplifiers
These use transmission lines to temporally split the signal and amplify each portion separately in order to achieve higher bandwidth than can be obtained from a single amplifying device. The outputs of each stage are combined in the output transmission line. This type of amplifier was commonly used on oscilloscopes as the final vertical amplifier. The transmission lines were often housed inside the display tube glass envelope.

Microwave amplifiers:
Travelling wave tube (TWT) amplifiers
Used for high power amplification at low microwave frequencies. They typically can amplify across a broad spectrum of frequencies; however, they are usually not as tunable as klystrons.

Klystrons
Very similar to TWT amplifiers, but more powerful and with a specific frequency "sweet spot". They generally are also much heavier than TWT amplifiers, and are therefore ill-suited for light-weight mobile applications. Klystrons are tunable, offering selective output within their specified frequency range.

Musical instrument (audio) amplifiers
An audio amplifier is usually used to amplify signals such as music or speech.

Other amplifier types:

Carbon microphone
One of the first devices used to amplify signals was the carbon microphone (effectively a sound-controlled variable resistor). By channeling a large electric current through the compressed carbon granules in the microphone, a small sound signal could produce a much larger electric signal. The carbon microphone was extremely important in early telecommunications; analog telephones in fact work without the use of any other amplifier. Before the invention of electronic amplifiers, mechanically coupled carbon microphones were also used as amplifiers in telephone repeaters for long distance service.

Magnetic amplifier
Main article: magnetic amplifier
A magnetic amplifier is a transformer-like device that makes use of the saturation of magnetic materials to produce amplification. It is a non-electronic electrical amplifier with no moving parts. The bandwidth of magnetic amplifiers extends to the hundreds of kilohertz.

Rotating electrical machinery amplifier
A Ward Leonard control is a rotating machine like an electrical generator that provides amplification of electrical signals by the conversion of mechanical energy to electrical energy. Changes in generator field current result in larger changes in the output current of the generator, providing gain. This class of device was used for smooth control of large motors, primarily for elevators and naval guns.

Johnsen-Rahbek effect amplifier
The earliest form of audio power amplifier was Edison's "electromotograph" loud-speaking telephone, which used a wetted rotating chalk cylinder in contact with a stationary contact. The friction between cylinder and contact varied with the current, providing gain. Edison discovered this effect in 1874, but the theory behind the Johnsen-Rahbek effect was not understood until the semiconductor era.

Mechanical amplifiers
Mechanical amplifiers were used in the pre-electronic era in specialized applications. Early autopilot units designed by Elmer Ambrose Sperry incorporated a mechanical amplifier using belts wrapped around rotating drums; a slight increase in the tension of the belt caused the drum to move the belt. A paired, opposing set of such drives made up a single amplifier. This amplified small gyro errors into signals large enough to move aircraft control surfaces. A similar mechanism was used in the Vannevar Bush differential analyzer.

Optical amplifiers

Optical amplifiers amplify light through the process of stimulated emission.

Miscellaneous types
There are also mechanical amplifiers, such as the automotive servo used in braking.
Relays can be included under the above definition of amplifiers, although their transfer function is not linear (that is, they are either open or closed).
Also purely mechanical manifestations of such digital amplifiers can be built (for theoretical, didactical purposes, or for entertainment), see e.g. domino computer.
Another type of amplifier is the fluidic amplifier, based on the fluidic triode.

Thapar University, (a private university) previously known as Thapar Institute of Engineering and Technology (before 2007)- was founded in 1956 by Karam Chand Thapar of the Thapar Group of companies. Situated in the city of Patiala in Punjab, it is one of north India's premier institutes of engineering and technology. Thapar University offers courses at the bachelors, masters and Ph. D., level in several disciplines of engineering and technology. Over 10,000 students have graduated from Thapar University. In a survey conducted by DataQuest, it was rated among the top 15 engineering schools in India.

Thaparian culture is based on overall growth. The students keep themselves busy in some activity or the other. These include various academic, cultural and literary activities. At the same time discipline is maintained by the institute to maintain focus on professional growth. The annual college festival "Aranya" has been quite a success among all colleges in Punjab. The institute also has an literary-cultural festival by the name "Saturnalia" held every year in March.

Campus
Thapar Institute of Engineering & Technology (TIET) is the major Institute located in the 250-acre (1.0 km2) Thapar Technology Campus (TTC) in the historic city of Patiala(Punjab). Other prominent institute is the L.M.Thapar School of Management. It is one of the premier institute of management in India which facilitate young minds having traits of management and technology blended together to form a perfect suit for current scenario.Other than Thapar Insitute of Engineering and Technology, the Thapar Technology campus also has Thapar Polytechnic, Thapar Centre for Industrial Research and Development


Academics
The Institute offers undergraduate programmes leading to Bachelor of Engineering (B.E.) degree and postgraduate programmes leading to Master of Engineering (M.E.), Master of Software Engineering, Master of Technology (M.Tech.), Master of Science (M.Sc.), Master of Computer Applications (M.C.A.), Doctor of Philosophy (Ph.D.), and Doctor of Science (D.Sc.) degrees. In addition, industry oriented and practice based Master's Degree programmes in various disciplines are offered in collaboration with TTTI, Chandigarh.Students have to take the AIEEE Exam in order to get admission into Thapar University for the undergraduate program and students take the MET exam for admission into graduate/postgraduate programs.

Recently, the institute has started MBA as well as dual MBA+BE five year integrated programme.

A number of Thapar graduates have made it to the IES. D.S.Kapur, a civil graduate of 1978 batch was all India IES Topper. Apart from the technical field, Thaparians have excelled in the administrative services.IAS and other Central Services also caught the fancy of the Thaparians, after a 1983-batch electronics and telecommunications graduate K. B. S. Sidhu set the trend, finishing among the IAS toppers in the 1984 batch.

The Management school i.e. L.M.Thapar School of Management has also marched its steps towards excellence. The students, most of whom have prior professional work experience, have been crossing the boundaries and are frequently visiting top institutes like IIM Bangalore and IIM Ahmedabad for project work and dissertation purposes.

LMTSOM is also hugely benefited by the presence of Science and Technology Entrepreneurs' Park which is a part of Thapar University. Management Research and Innovation Forum (MRIF) has been set up specifically for promoting management based research. It is looking forward for collaboration with prominent research centers across the world.


Activities
The most pronounced aspect of education at TIET is the extensive participation of students in extracurricular activities. These are carried out by various societes headed by one member of the faculty. MUDRA (Music and Dramatics Society) conducts its cultural nite and an inter-year cultural competition IZHAAR. LITSOC (Literary Society) is another popular society which conducts the annual inter-hostel literary festival ACUMEN. Other societes include ACID, CCS, IEEE (TIET chapter), SAE (TIET chapter), etc and various departmental societies.

The institute also organises a literary-cultural festival by the name Saturnalia held every year in March. This is complemented by a technical festival ARANYA, normally held in October-November each year. These events involve large participation from prestigious institutes from all over India and is graced by the presence of artists like JAL, KAILASH KHER, EUPHORIA etc. The students publish their own magazines, AVANT GARDE, which represents the views of the students along with addressing issues of the youth and nation, and ECLECTIZA, which emphasizes on the latest advancements and applications in the field of science, thus catering to the thirst of all the techees in the institute. The theatrical society is also one of the most active societies on campus.


History
Thapar Institute of Engineering & Technology (TIET) was established in 1956 with the goal of providing undergraduate and postgraduate education in Engineering and Technology, a close interaction with industry, and a strong emphasis on research. TIET has grown steadily in size and activities during the last four decades of its existence. Over 10,000 engineers have graduated from TIET. In recognition of its achievements, TIET was granted full autonomy and the status of a Deemed University in 1985 by the University Grants Commission.


The Thapar Group
Ballarpur Industries Limited, Bilt Paper Holdings Limited, Orient Engineering and Commercial Company Limited, The Pioneer, Sohna Stud Farm Pvt Limited, TT & G Trading Pvt Limited, iBilt Technologies Limited, Bilt Middle East Pvt Limited, Himalayan Hideaways Pvt Limited, Karam Chand Thapar & Bros Limited, Lavasa Corporation Limited and KCT Papers Limited are some of the Thapar group companies. Other Thapar group companies and concerns in India are, the Pioneer newspaper, Thapar house on Janpath lane, Tiger Bay restaurant, Global Green. The Crompton Greaves, Greaves Cotton and JCT group is with MM Thapar. His son Samir Thapar runs JCT Mills and JCT Limited and his son Arjun Thapar runs JCT electronics. Bilt Chemicals and Bharat Starch was vested with BM Thapar and hence would be under his sons Gautam and Karan Thapar's control. Gautam has also been named by L.M. Thapar as the successor of his group of companies. IM Thapar's son Vikram Thapar looks after his group which includes the Calcutta based coal trading business K.C Thapar started out with and prawn farms for prawn exports as well as the Tiger Bay restaurant chain. Thapar Institute of Engineering and Tech. is a group project funded by the Thapar's. JCT Mills FC is a Football club of JCT Mills.


Future Expansions
Patiala-based Thapar University (formerly Thapar Institute of Engineering and Technology) plans to set up two campuses over the next five years — one on a 14-acre campus near Chandigarh by 2010, and another in Chhattisgarh.It plans to offer courses in management and engineering at its proposed Chandigarh campus and will invest around Rs 30-35 crore.

The existing 250-acre campus in Patiala has a student strength of 4,600 and can accommodate around 6,000 students, according to Abhijit Mukherjee, director, Thapar University.

“The initial student strength at the new campus would be 200 but would go up to 2,000 eventually. Also, we will need 15-20 faculty members for the Chandigarh campus. The Patiala campus’ management school will be shifted to Chandigarh and the existing engineering courses will also be expanded. As of now, there are 300 students in management and 3,000 in engineering,” said Mukherjee.

As for a campus in central India, Thapar University has been invited by the government of Chhattisgarh to set up a large campus with residential facilities like the Patiala one .

The university is also keen on introducing new inter-disciplinary courses. Recently, it added courses in biology and biotechnology.

On the foreign-alliances front, it already has a tie-up with the University of Waterloo in Canada, Western Ontario and Virginia Tech, and is in talks with more institutes to have exchange programmes and research collaboration

A router is a networking device whose software and hardware are usually tailored to the tasks of routing and forwarding information. For example, on the Internet, information is directed to various paths by routers.
Routers connect two or more logical subnets, which do not necessarily map one-to-one to the physical interfaces of the router. The term "layer 3 switch" often is used interchangeably with router, but switch is a general term without a rigorous technical definition. In marketing usage, it is generally optimized for Ethernet LAN interfaces and may not have other physical interface types. In comparison, a network hub does not do any routing, instead every packet it receives on one network line gets forwarded to all the other network lines.

Routers operate in two different planes:
Control plane, in which the router learns the outgoing interface that is most appropriate for forwarding specific packets to specific destinations,
Forwarding plane, which is responsible for the actual process of sending a packet received on a logical interface to an outbound logical interface.

Control plane
Control plane processing leads to the construction of what is variously called a routing table or routing information base (RIB). The RIB may be used by the Forwarding Plane to look up the outbound interface for a given packet, or, depending on the router implementation, the Control Plane may populate a separate forwarding information base (FIB) with destination information. RIBs are optimized for efficient updating with control mechanisms such as routing protocols, while FIBs are optimized for the fastest possible lookup of the information needed to select the outbound interface.
The Control Plane constructs the routing table from knowledge of the up/down status of its local interfaces, from hard-coded static routes, and from exchanging routing protocol information with other routers. It is not compulsory for a router to use routing protocols to function, if for example it was configured solely with static routes. The routing table stores the best routes to certain network destinations, the "routing metrics" associated with those routes, and the path to the next hop router.
Routers do maintain state on the routes in the RIB/routing table, but this is quite distinct from not maintaining state on individual packets that have been forwarded.

Forwarding plane

For the pure Internet Protocol (IP) forwarding function, router design tries to minimize the state information kept on individual packets. Once a packet is forwarded, the router should no longer retain statistical information about it. It is the sending and receiving endpoints that keeps information about such things as errored or missing packets.
Forwarding decisions can involve decisions at layers other than the IP internetwork layer or OSI layer 3. Again, the marketing term switch can be applied to devices that have these capabilities. A function that forwards based on data link layer, or OSI layer 2, information, is properly called a bridge. Marketing literature may call it a layer 2 switch, but a switch has no precise definition.
Among the most important forwarding decisions is deciding what to do when congestion occurs, i.e., packets arrive at the router at a rate higher than the router can process. Three policies commonly used in the Internet are Tail drop, Random early detection, and Weighted random early detection. Tail drop is the simplest and most easily implemented; the router simply drops packets once the length of the queue exceeds the size of the buffers in the router. Random early detection (RED) probabilistically drops datagrams early when the queue exceeds a configured size. Weighted random early detection requires a weighted average queue size to exceed the configured size, so that short bursts will not trigger random drops.

Types of routers

Routers may provide connectivity inside enterprises, between enterprises and the Internet, and inside Internet Service Providers (ISP). The largest routers (for example the Cisco CRS-1 or Juniper T1600) interconnect ISPs, are used inside ISPs, or may be used in very large enterprise networks. The smallest routers provide connectivity for small and home offices.

Routers for Internet connectivity and internal use
Routers intended for ISP and major enterprise connectivity will almost invariably exchange routing information with the Border Gateway Protocol (BGP). RFC 4098[4] defines several types of BGP-speaking routers:
Edge Router: Placed at the edge of an ISP network, it speaks external BGP (eBGP) to a BGP speaker in another provider or large enterprise Autonomous System (AS).
Subscriber Edge Router: Located at the edge of the subscriber's network, it speaks eBGP to its provider's AS(s). It belongs to an end user (enterprise) organization.
Inter-provider Border Router: Interconnecting ISPs, this is a BGP speaking router that maintains BGP sessions with other BGP speaking routers in other providers' ASes.
Core router: A router that resides within the middle or backbone of the LAN network rather than at its periphery.
Within an ISP: Internal to the provider's AS, such a router speaks internal BGP (iBGP) to that provider's edge routers, other intra-provider core routers, or the provider's inter-provider border routers.
"Internet backbone:" The Internet does not have a clearly identifiable backbone, as did its predecessors. See default-free zone (DFZ). Nevertheless, it is the major ISPs' routers that make up what many would consider the core. These ISPs operate all four types of the BGP-speaking routers described here. In ISP usage, a "core" router is internal to an ISP, and used to interconnect its edge and border routers. Core routers may also have specialized functions in virtual private networks based on a combination of BGP and Multi-Protocol Label Switching (MPLS).
Routers are also used for port forwarding for private servers.

[edit] Small Office Home Office (SOHO) connectivity
Main article: Residential gateway
Residential gateways (often called routers) are frequently used in homes to connect to a broadband service, such as IP over cable or DSL. A home router may allow connectivity to an enterprise via a secure Virtual Private Network.
While functionally similar to routers, residential gateways use port address translation in addition to routing. Instead of connecting local computers to the remote network directly, a residential gateway makes multiple local computers appear to be a single computer.

Enterprise routers
All sizes of routers may be found inside enterprises. The most powerful routers tend to be found in ISPs and academic & research facilities. Large businesses may also need powerful routers.
A three-layer model is in common use, not all of which need be present in smaller networks.

Access
Access routers, including SOHO, are located at customer sites such as branch offices that do not need hierarchical routing of their own. Typically, they are optimized for low cost.

Distribution
Distribution routers aggregate traffic from multiple access routers, either at the same site, or to collect the data streams from multiple sites to a major enterprise location. Distribution routers often are responsible for enforcing quality of service across a WAN, so they may have considerable memory, multiple WAN interfaces, and substantial processing intelligence.
They may also provide connectivity to groups of servers or to external networks. In the latter application, the router's functionality must be carefully considered as part of the overall security architecture. Separate from the router may be a Firewalled or VPN concentrator, or the router may include these and other security functions.
When an enterprise is primarily on one campus, there may not be a distinct distribution tier, other than perhaps off-campus access. In such cases, the access routers, connected to LANs, interconnect via core routers.