Semi-Automatic Ground Environment
The Semi-Automatic Ground Environment was a system of large computers and associated networking equipment that coordinated data from many radar sites and processed it to produce a single unified image of the airspace over a wide area. SAGE directed and controlled the NORAD response to a Soviet air attack, operating in this role from the late 1950s into the 1980s, its enormous computers and huge displays remain a part of cold war lore, a common prop in movies such as Dr. Strangelove and Colossus; the processing power behind SAGE was supplied by the largest computer built, the AN/FSQ-7. Each SAGE Direction Center housed an FSQ-7 which occupied an entire floor 22,000 square feet not including supporting equipment. Information was fed to the DCs from a network of radar stations as well as readiness information from various defence sites; the computers, based on the raw radar data, developed "tracks" for the reported targets, automatically calculated which defences were within range. Operators used light guns to select targets on-screen for further information, select one of the available defences, issue commands to attack.
These commands would be automatically sent to the defence site via teleprinter. Connecting the various sites was an enormous network of telephones and teleprinters. Additions to the system allowed SAGE's tracking data to be sent directly to CIM-10 Bomarc missiles and some of the US Air Force's interceptor aircraft in-flight, directly updating their autopilots to maintain an intercept course without operator intervention; each DC forwarded data to a Combat Center for "supervision of the several sectors within the division". SAGE became operational in early 1960s at a combined cost of billions of dollars, it was noted that the deployment cost more than the Manhattan Project, which it was, in a way, defending against. Throughout its development, there were continual concerns about its real ability to deal with large attacks, the Operation Skyshield tests showed that only about one-fourth of enemy bombers would have been intercepted. SAGE was the backbone of NORAD's air defense system into the 1980s, by which time the tube-based FSQ-7's were costly to maintain and outdated.
Today the same command and control task is carried out by microcomputers, based on the same basic underlying data. Just prior to World War II, Royal Air Force tests with the new Chain Home radars had demonstrated that relaying information to the fighter aircraft directly from the radar sites was not feasible; the radars determined the map coordinates of the enemy, but could not see the fighters at the same time. This meant the fighters had to be able to determine where to fly to perform an interception but were unaware of their own exact location and unable to calculate an interception while flying their aircraft; the solution was to send all of the radar information to a central control station where operators collated the reports into single tracks, reported these tracks out to the airbases, or sectors. The sectors used additional systems to track their own aircraft, plotting both on a single large map. Operators viewing the map could easily see what direction their fighters would have to fly to approach their targets and relay that by telling them to fly along a certain heading or vector.
This Dowding system was the first ground-controlled interception system of large scale, covering the entirety of the UK. It proved enormously successful during the Battle of Britain, is credited as being a key part of the RAF's success. However, the system was slow providing information, up to five minutes out of date. Against propeller driven bombers flying at 225 miles per hour this was not a serious concern, but it was clear the system would be of little use against jet-powered bombers flying at 600 miles per hour; the system was extremely expensive in manpower terms, requiring hundreds of telephone operators, plotters and all of the radar operators on top of that. This was a serious drain on manpower reserves, making it difficult to expand the network; the idea of using a computer to handle the task of taking reports and developing tracks had been explored beginning late in the war. By 1944, analog computers had been installed at the CH stations to automatically convert radar readings into map locations, eliminating two people.
Meanwhile, the Royal Navy began experimenting with the Comprehensive Display System, another analog computer that took X and Y locations from a map and automatically generated tracks from repeated inputs. Similar systems began development with the Royal Canadian Navy, DATAR, the US Navy, the Naval Tactical Data System. A similar system was specified for the Nike SAM project referring to a US version of CDS, coordinating the defense over a battle area so that multiple batteries did not fire on a single target. However, all of these systems were small in geographic scale tracking within a city-sized area; when the Soviets tested RDS-1 in August 1949, the topic of air defense of the US became important for the first time. A study group, the "Air Defense Systems Engineering Committee" was set up under the direction of Dr. George Valley to consider the problem, is known to history as the Valley Committee, their December report noted a key problem in air defense using ground-based radars. A bomber approaching a radar station would detect the signals from the radar long before the reflection off the bomber was strong enough to be detected by the station.
The committee suggested that when this
Intercontinental ballistic missile
An intercontinental ballistic missile is a guided ballistic missile with a minimum range of 5,500 kilometres designed for nuclear weapons delivery. Conventional and biological weapons can be delivered with varying effectiveness, but have never been deployed on ICBMs. Most modern designs support multiple independently targetable reentry vehicles, allowing a single missile to carry several warheads, each of which can strike a different target. Early ICBMs had limited precision, which made them suitable for use only against the largest targets, such as cities, they were seen as a "safe" basing option, one that would keep the deterrent force close to home where it would be difficult to attack. Attacks against military targets still demanded the use of a more precise, manned bomber. Second- and third-generation designs improved accuracy to the point where the smallest point targets can be attacked. ICBMs are differentiated by having greater range and speed than other ballistic missiles: intermediate-range ballistic missiles, medium-range ballistic missiles, short-range ballistic missiles and tactical ballistic missiles.
Short and medium-range ballistic missiles are known collectively as theatre ballistic missiles. The development of the world's first practical design for an ICBM, A9/10, intended for use in bombing New York and other American cities, was undertaken in Nazi Germany by the team of Wernher von Braun under Projekt Amerika; the ICBM A9/A10 rocket was intended to be guided by radio, but was changed to be a piloted craft after the failure of Operation Elster. The second stage of the A9/A10 rocket was tested a few times in January and February 1945; the progenitor of the A9/A10 was the German V-2 rocket designed by von Braun and used at the end of World War II to bomb British and Belgian cities. All of these rockets used liquid propellants. Following the war, von Braun and other leading German scientists were relocated to the United States to work directly for the US Army through Operation Paperclip, developing the IRBMs, ICBMs, launchers; this technology was predicted by US Army General Hap Arnold, who wrote in 1943: Someday, not too distant, there can come streaking out of somewhere – we won't be able to hear it, it will come so fast – some kind of gadget with an explosive so powerful that one projectile will be able to wipe out this city of Washington.
In the immediate post-war era, the US and USSR both started rocket research programs based on the German wartime designs the V-2. In the US, each branch of the military started its own programs, leading to considerable duplication of effort. In the USSR, rocket research was centrally organized, although several teams worked on different designs. Early designs from both countries were short-range missiles, like the V-2, but improvements followed. In the USSR, early development was focused on missiles able to attack European targets; this changed in 1953 when Sergei Korolyov was directed to start development of a true ICBM able to deliver newly developed hydrogen bombs. Given steady funding throughout, the R-7 developed with some speed; the first launch led to an unintended crash 400 km from the site. The first successful test followed on 21 August 1957; the first strategic-missile unit became operational on 9 February 1959 at Plesetsk in north-west Russia. It was the same R-7 launch vehicle that placed the first artificial satellite in space, Sputnik, on 4 October 1957.
The first human spaceflight in history was accomplished on a derivative of R-7, Vostok, on 12 April 1961, by Soviet cosmonaut Yuri Gagarin. A modernized version of the R-7 is still used as the launch vehicle for the Soviet/Russian Soyuz spacecraft, marking more than 60 years of operational history of Sergei Korolyov's original rocket design; the U. S. initiated ICBM research in 1946 with the RTV-A-2 Hiroc project. This was a three-stage effort with the ICBM development not starting until the third stage. However, funding was cut after only three successful launches in 1948 of the second stage design, used to test variations on the V-2 design. With overwhelming air superiority and intercontinental bombers, the newly forming US Air Force did not take the problem of ICBM development seriously. Things changed in 1953 with the Soviet testing of their first thermonuclear weapon, but it was not until 1954 that the Atlas missile program was given the highest national priority; the Atlas A first flew on 11 June 1957.
The first successful flight of an Atlas missile to full range occurred 28 November 1958. The first armed version of the Atlas, the Atlas D, was declared operational in January 1959 at Vandenberg, although it had not yet flown; the first test flight was carried out on 9 July 1959, the missile was accepted for service on 1 September. The R-7 and Atlas each required a large launch facility, making them vulnerable to attack, could not be kept in a ready state. Failure rates were high throughout the early years of ICBM technology. Human spaceflight programs served as a visible means of demonstrating confidence in reliability, with successes translating directly to national defense implications; the US was well behind the Soviet Union in the Space Race, so U. S. President John F. Kennedy increased the stakes with the Apollo program, which used Saturn rocket technology, funded by President Dwight D. Eisenhower
The Advanced Research Projects Agency Network was an early packet-switching network and the first network to implement the TCP/IP protocol suite. Both technologies became the technical foundation of the Internet; the ARPANET was founded by the Advanced Research Projects Agency of the United States Department of Defense. The packet-switching methodology employed in the ARPANET was based on concepts and designs by Leonard Kleinrock, Paul Baran, Donald Davies, Lawrence Roberts; the TCP/IP communications protocols were developed for the ARPANET by computer scientists Robert Kahn and Vint Cerf, incorporated concepts from the French CYCLADES project directed by Louis Pouzin. As the project progressed, protocols for internetworking were developed by which multiple separate networks could be joined into a network of networks. Access to the ARPANET was expanded in 1981, when the National Science Foundation funded the Computer Science Network. In 1982, the Internet protocol suite was introduced as the standard networking protocol on the ARPANET.
In the early 1980s the NSF funded the establishment of national supercomputing centers at several universities and provided interconnectivity in 1986 with the NSFNET project, which created network access to the supercomputer sites in the United States from research and education organizations. The ARPANET was decommissioned in 1989. Voice and data communications were based on methods of circuit switching, as exemplified in the traditional telephone network, wherein each telephone call is allocated a dedicated, end to end, electronic connection between the two communicating stations; such stations might be computers. The temporarily dedicated line comprises many intermediary lines which are assembled into a chain that reaches from the originating station to the destination station. With packet switching, a network could share a single communication link for communication between multiple pairs of receivers and transmitters; the earliest ideas for a computer network intended to allow general communications among computer users were formulated by computer scientist J. C. R. Licklider of Bolt and Newman, in April 1963, in memoranda discussing the concept of the "Intergalactic Computer Network".
Those ideas encompassed many of the features of the contemporary Internet. In October 1963, Licklider was appointed head of the Behavioral Sciences and Command and Control programs at the Defense Department's Advanced Research Projects Agency, he convinced Ivan Sutherland and Bob Taylor that this network concept was important and merited development, although Licklider left ARPA before any contracts were assigned for development. Sutherland and Taylor continued their interest in creating the network, in part, to allow ARPA-sponsored researchers at various corporate and academic locales to utilize computers provided by ARPA, and, in part, to distribute new software and other computer science results. Taylor had three computer terminals in his office, each connected to separate computers, which ARPA was funding: one for the System Development Corporation Q-32 in Santa Monica, one for Project Genie at the University of California and another for Multics at the Massachusetts Institute of Technology.
Taylor recalls the circumstance: "For each of these three terminals, I had three different sets of user commands. So, if I was talking online with someone at S. D. C. and I wanted to talk to someone I knew at Berkeley, or M. I. T. about this, I had to get up from the S. D. C. Terminal, log into the other terminal and get in touch with them. I said, "Oh Man!", it's obvious what to do: If you have these three terminals, there ought to be one terminal that goes anywhere you want to go. That idea is the ARPANET". Meanwhile, since the early 1960s, Paul Baran at the RAND Corporation had been researching systems that could survive nuclear war and developed the idea of distributed adaptive message block switching. Donald Davies at the United Kingdom's National Physical Laboratory independently invented the same concept in 1965, his work, presented by a colleague caught the attention of ARPANET developers at a conference in Gatlinburg, Tennessee, in October 1967. He gave the first public demonstration, having coined the term packet switching, on 5 August 1968 and incorporated it into the NPL network in England.
Elizabeth Feinler created the first Resource Handbook for ARPANET in 1969 which led to the development of the ARPANET directory. The directory, built by Feinler and a team made it possible to navigate the ARPANET. Larry Roberts at ARPA applied Davies' concepts of packet switching for the ARPANET; the NPL network followed by the ARPANET were the first two networks in the world to use packet switching, were themselves connected together in 1973. Bob Taylor convinced ARPA's Director Charles M. Herzfeld to fund a network project in February 1966, Herzfeld transferred a million dollars from a ballistic missile defense program to Taylor's budget. Taylor hired Larry Roberts as a program manager in the ARPA Information Processing Techniques Office in January 1967 to work on the ARPANET. In April 1967, Roberts held a design session on technical standards; the initial standards for identification and authentication of users, transmission of characters, error checking and retransmission procedures were discussed.
At the meeting, Wesley Clark proposed minicomputers called Interface Message Processors should be used to interface to the network rather than the large mainframes that would be the nodes of the ARPANET. Roberts modified the ARPANET plan to incorporate Clark's suggestion; the plan was presented at the ACM Symposium in Gatlinburg, Tennessee, in October 1967. Donald Davies' work on packet switc
The SM-65 Atlas was the first operational intercontinental ballistic missile developed by the United States and the first member of the Atlas rocket family. It was built for the U. S. Air Force by Convair Division of General Dynamics at the Kearny Mesa assembly plant north of San Diego. Atlas became operational as an ICBM in October 1959 and was used as a first stage for satellite launch vehicles for half a century; the Atlas missile's warhead was over 100 times more powerful than the bomb dropped over Nagasaki in 1945. An initial development contract was given to Consolidated Vultee Aircraft on 16 January 1951 for what was called MX-1593, it had a low priority. The 1953 testing of the first dry fuel H-bomb in the Soviet Union led to the project being accelerated; the initial design completed by Convair in 1953 was larger than the missile that entered service. Estimated warhead weight was lowered from 8,000 lb to 3,000 lb based on favorable U. S. nuclear warhead tests in early 1954, on 14 May 1954 the Atlas program was formally given the highest national priority.
A major development and test contract was awarded to Convair on 14 January 1955 for a 10-foot diameter missile to weigh about 250,000 lb. Atlas development was controlled by the Air Force's Western Development Division, WDD part of the Air Force Ballistic Missile Division. Contracts for warhead and propulsion were handled separately by WDD; the first successful flight of a instrumented Atlas missile to full range occurred 28 November 1958. Atlas ICBMs were deployed operationally from 31 October 1959 to 12 April 1965. On 18 December 1958, the launch of Atlas 10B sent the missile into orbit around the Earth carrying the "SCORE" communications payload. Atlas 10B/SCORE, at 8,750 lb was the heaviest man-made object in orbit, the first voice relay satellite, the first man-made object in space visible to the naked eye due to the large, mirror-polished stainless steel tank; this was the first flight in. Many retired Atlas ICBMs would be used as launch vehicles, most with an added spin-stabilized solid rocket motor upper stage for polar orbit military payloads.
Before its military use ended in 1965, Atlas had placed four Project Mercury astronauts in orbit and was becoming the foundation for a family of successful space launch vehicles, most notably Atlas Agena and Atlas Centaur. Mergers led to the acquisition of the Atlas Centaur line by Lockheed Martin, which became part of United Launch Alliance. Today Lockheed Martin and ULA support a new Atlas rocket family based on the larger "Atlas V" which still uses the unique and efficient Centaur upper stage. Atlas V stage one is powered by a Russian RD-180 oxygen/kerosene engine and uses conventional aluminum isogrid tanks, rather than the thin-wall, pressure-stabilized stainless steel tanks of the original Convair Atlas. Payload weights have increased along with launch vehicle weights over the years, so the current Atlas V family serves many of the same types of commercial, DoD, planetary missions as earlier Atlas Centaurs. Shortly before his death, John von Neumann headed the top secret von Neumann ICBM committee.
Its purpose was to decide on the feasibility of building an ICBM large enough to carry a thermonuclear weapon. Von Neumann had long argued that while the technical obstacles were indeed formidable, they could be overcome in time. Events were proving him right; the weapons had become smaller, diode–transistor logic enabled the construction of compact guidance computers. The committee approved a "radical reorganization" and speeding up of the Atlas program. Atlas was informally classified as a "stage-and-a-half" rocket. At staging, the booster engines would be shut off and a series of mechanical and hydraulic mechanisms would close the plumbing lines to them; the booster section would be released by a series of hydraulic clamps and slide off the missile. From there on, the sustainer and verniers would operate by themselves. Booster staging took place at two minutes into launch, although the exact timing could vary depending on the model of Atlas as well as the particular mission being flown; the booster engine consisted of two large thrust chambers.
On the Atlas A/B/C, one turbopump assembly powered both booster engines. On the Atlas D, the booster engines had separate pump assemblies. On the Atlas E/F, each booster turbopump got its own gas generator. Space launcher variants of the Atlas used the MA-5 propulsion system with twin turbopumps on each booster engine, driven by a common gas generator; the boosters were more powerful than the sustainer engine and did most of the lifting for the first two minutes of flight. In addition to pitch and yaw control, they could perform roll control in the event of a vernier failure; the sustainer engine on all Atlas variants consisted of a single thrust chamber with its own turbopump and gas generator, two small pressure-fed vernier engines. The verniers provided final velocity trim; the total sea level thrust of all five thrust chambers was 360,000 lbf for a standard Atlas
The Central Artery/Tunnel Project, known unofficially as the Big Dig, was a megaproject in Boston that rerouted the Central Artery of Interstate 93, the chief highway through the heart of the city, into the 1.5-mile Thomas P. O'Neill Jr. Tunnel; the project included the construction of the Ted Williams Tunnel, the Leonard P. Zakim Bunker Hill Memorial Bridge over the Charles River, the Rose Kennedy Greenway in the space vacated by the previous I-93 elevated roadway; the plan was to include a rail connection between Boston's two major train terminals. Planning began in 1982; the Big Dig was the most expensive highway project in the US, was plagued by cost overruns, leaks, design flaws, charges of poor execution and use of substandard materials, criminal arrests, one death. The project was scheduled to be completed in 1998 at an estimated cost of $2.8 billion. However, the project was completed in December 2007 at a cost of over $14.6 billion as of 2006. The Boston Globe estimated that the project will cost $22 billion, including interest, that it would not be paid off until 2038.
As a result of a death and other design flaws and Parsons Brinckerhoff—the consortium that oversaw the project—agreed to pay $407 million in restitution and several smaller companies agreed to pay a combined sum of $51 million. The Rose Fitzgerald Kennedy Greenway is a 1.5-mile-long series of parks and public spaces, which were the final part of the Big Dig after Interstate 93 was put underground. The Greenway was named in honor of Kennedy family matriarch Rose Fitzgerald Kennedy, was dedicated on July 26, 2004; this project was developed in response to traffic congestion on Boston's tangled streets which were laid out long before the advent of the automobile. As early as 1930 the city's Planning Board recommended a raised express highway running north-south through the downtown district in order to draw traffic off the city streets. Commissioner of Public Works William Callahan promoted plans for an elevated expressway, constructed between the downtown area and the waterfront. Governor John Volpe interceded in the 1950s to change the design of the last section of the Central Artery putting it underground through the Dewey Square Tunnel.
While traffic moved somewhat better, the other problems remained. There was chronic congestion on the Central Artery, an elevated six-lane highway through the center of downtown Boston, which was, in the words of Pete Sigmund, "like a funnel full of slowly-moving, or stopped, cars." In 1959, the 1.5-mile-long road section carried 75,000 vehicles a day, but by the 1990s, this had grown to 190,000 vehicles a day. Traffic jams of 16 hours were predicted for 2010; the expressway had tight turns, an excessive number of entrances and exits, entrance ramps without merge lanes, as the decades passed, had continually escalating vehicular traffic, well beyond its design capacity. Local businesses again wanted relief, city leaders sought a reuniting of the waterfront with the city, nearby residents desired removal of the matte green-painted elevated road which mayor Thomas Menino called Boston's "other Green Monster". MIT engineers Bill Reynolds and Frederick P. Salvucci envisioned moving the whole expressway underground.
Another important motivation for the final form of the Big Dig was the abandonment of the Massachusetts Department of Public Works' intended expressway system through and around Boston. The Central Artery, as part of Mass. DPW's Master Plan of 1948, was planned to be the downtown Boston stretch of Interstate 95, was signed as such; the Inner Belt District was to pass to the west of the downtown core, through the neighborhood of Roxbury and the cities of Brookline and Somerville. Earlier controversies over impact of the Boston extension of the Massachusetts Turnpike on the populated neighborhood of Brighton, the additional large amount of housing that would have had to be destroyed led to massive community opposition to both the Inner Belt and the Boston section of I-95. Building demolition and land clearances for I-95 through the neighborhoods of Roxbury, Jamaica Plain, Roslindale led to secession threats by Hyde Park, Boston's youngest and southernmost neighborhood. By 1972, with only a minimum of work done on the I-95 right of way and none on the massively disruptive Inner Belt, Governor Francis Sargent put a moratorium on highway construction within the MA-128 corridor, except for the final short stretch of Interstate 93.
In 1974, the remainder of the Master Plan was canceled, leaving Boston with a overstressed expressway system for the existing traffic. With ever-increasing traffic volumes funneled onto I-93 alone, the Central Artery became chronically gridlocked; the Sargent moratorium led to the rerouting of I-95 away from Boston around the MA-128 beltway and the conversion of the cleared land in the southern part of the city into the Southwest Corridor linear park, as well as a new right-of-way for the Orange Line subway and Amtrak. Parts of the planned I-695 r
Boston is the capital and most populous city of the Commonwealth of Massachusetts in the United States. The city proper covers 48 square miles with an estimated population of 685,094 in 2017, making it the most populous city in New England. Boston is the seat of Suffolk County as well, although the county government was disbanded on July 1, 1999; the city is the economic and cultural anchor of a larger metropolitan area known as Greater Boston, a metropolitan statistical area home to a census-estimated 4.8 million people in 2016 and ranking as the tenth-largest such area in the country. As a combined statistical area, this wider commuting region is home to some 8.2 million people, making it the sixth-largest in the United States. Boston is one of the oldest cities in the United States, founded on the Shawmut Peninsula in 1630 by Puritan settlers from England, it was the scene of several key events of the American Revolution, such as the Boston Massacre, the Boston Tea Party, the Battle of Bunker Hill, the Siege of Boston.
Upon gaining U. S. independence from Great Britain, it continued to be an important port and manufacturing hub as well as a center for education and culture. The city has expanded beyond the original peninsula through land reclamation and municipal annexation, its rich history attracts many tourists, with Faneuil Hall alone drawing more than 20 million visitors per year. Boston's many firsts include the United States' first public park, first public or state school and first subway system; the Boston area's many colleges and universities make it an international center of higher education, including law, medicine and business, the city is considered to be a world leader in innovation and entrepreneurship, with nearly 2,000 startups. Boston's economic base includes finance and business services, information technology, government activities. Households in the city claim the highest average rate of philanthropy in the United States; the city has one of the highest costs of living in the United States as it has undergone gentrification, though it remains high on world livability rankings.
Boston's early European settlers had first called the area Trimountaine but renamed it Boston after Boston, England, the origin of several prominent colonists. The renaming on September 7, 1630, was by Puritan colonists from England who had moved over from Charlestown earlier that year in quest for fresh water, their settlement was limited to the Shawmut Peninsula, at that time surrounded by the Massachusetts Bay and Charles River and connected to the mainland by a narrow isthmus. The peninsula is thought to have been inhabited as early as 5000 BC. In 1629, the Massachusetts Bay Colony's first governor John Winthrop led the signing of the Cambridge Agreement, a key founding document of the city. Puritan ethics and their focus on education influenced its early history. Over the next 130 years, the city participated in four French and Indian Wars, until the British defeated the French and their Indian allies in North America. Boston was the largest town in British America until Philadelphia grew larger in the mid-18th century.
Boston's oceanfront location made it a lively port, the city engaged in shipping and fishing during its colonial days. However, Boston stagnated in the decades prior to the Revolution. By the mid-18th century, New York City and Philadelphia surpassed Boston in wealth. Boston encountered financial difficulties as other cities in New England grew rapidly. Many of the crucial events of the American Revolution occurred near Boston. Boston's penchant for mob action along with the colonists' growing distrust in Britain fostered a revolutionary spirit in the city; when the British government passed the Stamp Act in 1765, a Boston mob ravaged the homes of Andrew Oliver, the official tasked with enforcing the Act, Thomas Hutchinson the Lieutenant Governor of Massachusetts. The British sent two regiments to Boston in 1768 in an attempt to quell the angry colonists; this did not sit well with the colonists. In 1770, during the Boston Massacre, the army killed several people in response to a mob in Boston.
The colonists compelled the British to withdraw their troops. The event was publicized and fueled a revolutionary movement in America. In 1773, Britain passed the Tea Act. Many of the colonists saw the act as an attempt to force them to accept the taxes established by the Townshend Acts; the act prompted the Boston Tea Party, where a group of rebels threw an entire shipment of tea sent by the British East India Company into Boston Harbor. The Boston Tea Party was a key event leading up to the revolution, as the British government responded furiously with the Intolerable Acts, demanding compensation for the lost tea from the rebels; this led to the American Revolutionary War. The war began in the area surrounding Boston with the Battles of Concord. Boston itself was besieged for a year during the Siege of Boston, which began on April 19, 1775; the New England militia impeded the movement of the British Army. William Howe, 5th Viscount Howe the commander-in-chief of the British forces in North America, led the British army in the siege.
On June 17, the British captured the Charlestown peninsula in Boston, during the Battle of Bunker Hill. The British army outnumbered the militia stationed there, but it was a Py
Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design and manage complex systems over their life cycles. At its core, systems engineering utilizes systems thinking principles to organize this body of knowledge; the individual outcome of such efforts, an engineered system, can be defined as a combination of components that work in synergy to collectively perform a useful function. Issues such as requirements engineering, logistics, coordination of different teams and evaluation, maintainability and many other disciplines necessary for successful system development, design and ultimate decommission become more difficult when dealing with large or complex projects. Systems engineering deals with work-processes, optimization methods, risk management tools in such projects, it overlaps technical and human-centered disciplines such as industrial engineering, mechanical engineering, manufacturing engineering, control engineering, software engineering, electrical engineering, organizational studies, civil engineering and project management.
Systems engineering ensures that all aspects of a project or system are considered, integrated into a whole. The systems engineering process is a discovery process, quite unlike a manufacturing process. A manufacturing process is focused on repetitive activities that achieve high quality outputs with minimum cost and time; the systems engineering process must begin by discovering the real problems that need to be resolved, identifying the most probable or highest impact failures that can occur – systems engineering involves finding solutions to these problems. The term systems engineering can be traced back to Bell Telephone Laboratories in the 1940s; the need to identify and manipulate the properties of a system as a whole, which in complex engineering projects may differ from the sum of the parts' properties, motivated various industries those developing systems for the U. S. Military; when it was no longer possible to rely on design evolution to improve upon a system and the existing tools were not sufficient to meet growing demands, new methods began to be developed that addressed the complexity directly.
The continuing evolution of systems engineering comprises the development and identification of new methods and modeling techniques. These methods aid in a better comprehension of the design and developmental control of engineering systems as they grow more complex. Popular tools that are used in the systems engineering context were developed during these times, including USL, UML, QFD, IDEF0. In 1990, a professional society for systems engineering, the National Council on Systems Engineering, was founded by representatives from a number of U. S. corporations and organizations. NCOSE was created to address the need for improvements in systems engineering practices and education; as a result of growing involvement from systems engineers outside of the U. S. the name of the organization was changed to the International Council on Systems Engineering in 1995. Schools in several countries offer graduate programs in systems engineering, continuing education options are available for practicing engineers.
Systems engineering signifies only an approach and, more a discipline in engineering. The aim of education in systems engineering is to formalize various approaches and in doing so, identify new methods and research opportunities similar to that which occurs in other fields of engineering; as an approach, systems engineering is interdisciplinary in flavour. The traditional scope of engineering embraces the conception, development and operation of physical systems. Systems engineering, as conceived, falls within this scope. "Systems engineering", in this sense of the term, refers to the building of engineering concepts. The use of the term "systems engineer" has evolved over time to embrace a wider, more holistic concept of "systems" and of engineering processes; this evolution of the definition has been a subject of ongoing controversy, the term continues to apply to both the narrower and broader scope. Traditional systems engineering was seen as a branch of engineering in the classical sense, that is, as applied only to physical systems, such as spacecraft and aircraft.
More systems engineering has evolved to a take on a broader meaning when humans were seen as an essential component of a system. Checkland, for example, captures the broader meaning of systems engineering by stating that'engineering' "can be read in its general sense. Enterprise Systems Engineering pertains to the view of enterprises, that is, organizations or combinations of organizations, as systems. Service Systems Engineering has to do with the engineering of service systems. Checkland defines a service system as a system, conceived as serving another system. Most civil infrastructure systems are service systems. Systems engineering focuses on analyzing and eliciting customer needs and required functionality early in the development cycle, documenting requirements proceeding with design synthesis and system validation while considering the complete problem, the system lifecycle; this includes understanding all of the stakeholders involved. Oliver et al. claim that the systems engineerin