Tacoma Narrows Bridge (1940)
It opened to traffic on July 1,1940, and dramatically collapsed into Puget Sound on November 7 of the same year. At the time of its construction, the bridge was the third-longest suspension bridge in the world in terms of main span length, behind the Golden Gate Bridge, construction on the bridge began in September 1938. From the time the deck was built, it began to move vertically in windy conditions, the motion was observed even when the bridge opened to the public. Several measures aimed at stopping the motion were ineffective, and the main span finally collapsed under 40-mile-per-hour wind conditions the morning of November 7,1940. Following the collapse, the United States involvement in World War II delayed plans to replace the bridge, the portions of the bridge still standing after the collapse, including the towers and cables, were dismantled and sold as scrap metal. Nearly 10 years after the bridge collapsed, a new Tacoma Narrows Bridge opened in the location, using the original bridges tower pedestals.
The portion of the bridge fell into the water now serves as an artificial reef. The bridges collapse had an effect on science and engineering. Its failure boosted research in the field of bridge aerodynamics-aeroelastics, the Tacoma Chamber of Commerce began campaigning and funding studies in 1923. Several noted bridge engineers, including Joseph B, who went on to be chief engineer of the Golden Gate Bridge, and David B. Steinman, who went on to design the Mackinac Bridge, were consulted, another problem with financing the first bridge was buying out the ferry contract from a private firm running service on the Narrows at the time. The Washington State legislature created the Washington State Toll Bridge Authority and appropriated $5,000 to study the request by Tacoma, preliminary construction plans by the Washington Department of Highways had called for a set of 25-foot-deep trusses to sit beneath the roadway and stiffen it. Their theory of elastic distribution extended the theory that was originally devised by the Austrian engineer Josef Melan to horizontal bending under static wind load.
They showed that the stiffness of the cables would absorb up to one-half of the static wind pressure pushing a suspended structure laterally. This energy would be transmitted to the anchorages and towers, using this theory, Moisseiff argued for stiffening the bridge with a set of eight-foot-deep plate girders rather than the 25 feet -deep trusses proposed by the Washington Toll Bridge Authority. This approach meant a slimmer, more elegant design, and reduced the costs as compared with the Highway Departments design proposed by Eldridge. Moisseiffs design won out, inasmuch as the proposal was considered to be too expensive. On June 23,1938, the PWA approved nearly $6 million for the Tacoma Narrows Bridge, another $1.6 million was to be collected from tolls to cover the estimated total $8 million cost
In urban design, a terminating vista is a building or monument that stands at the end or in the middle of a road, so that when one is looking up the street the view ends with the site. Terminating vistas are considered an important method of adding aesthetic appeal to a city, common terminating vistas include government buildings, war memorials and other important structures. Standing at the end of a street adds grandeur to a structure, the important disadvantage of terminating vistas is that they make traffic more complicated and prevent a simple grid system of city blocks. To accommodate them, large circles or other techniques have to be employed to get traffic around the monument. Cities on a system such as New York City thus have few terminating vistas. A prominent NYC exception is the controversial MetLife Building, which was built on top of Park Avenue. A city particularly known for its terminating vistas is Paris, where many of the largest streets end in monuments and structures such as the Arc de Triomphe, another well-known example is Washington, D. C.
Philadelphias City Hall is another example, situated on Penn Square where Broad, the two streets form the north-south and east-west axes of the citys core grid, leaving the large masonry structure visible from all sections of the city. The lost art of the Terminated Vista - UrbanIndy description Get to Know the Awkwardly-Named Terminated Vista - Placemakers
Positive feedback is a process that occurs in a feedback loop in which the effects of a small disturbance on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn more of A. In contrast, a system in which the results of an act to reduce or counteract it has negative feedback. Both concepts play an important role in science and engineering, including biology, mathematically, positive feedback is defined as a positive loop gain around a closed loop of cause and effect. That is, positive feedback is in phase with the input, Positive feedback tends to cause system instability. When the loop gain is positive and above 1, there will typically be exponential growth, increasing oscillations, system parameters will typically accelerate towards extreme values, which may damage or destroy the system, or may end with the system latched into a new stable state. Positive feedback may be controlled by signals in the system being filtered, damped, or limited, Positive feedback is used in digital electronics to force voltages away from intermediate voltages into 0 and 1 states.
On the other hand, thermal runaway is a positive feedback that can destroy semiconductor junctions, Positive feedback in chemical reactions can increase the rate of reactions, and in some cases can lead to explosions. Positive feedback in mechanical design causes tipping-point, or over-centre, mechanisms to snap into position, for example in switches, out of control, it can cause bridges to collapse. Positive feedback in systems can cause boom-then-bust cycles. Positive feedback enhances or amplifies an effect by it having an influence on the process gave rise to it. For example, when part of an output signal returns to the input, and is in phase with it. The feedback from the outcome to the process can be direct. Such systems can give rich qualitative behaviors, but whether the feedback is positive or negative in sign has an extremely important influence on the results. Positive feedback reinforces and negative feedback moderates the original process and negative in this sense refer to loop gains greater than or less than zero, and do not imply any value judgements as to the desirability of the outcomes or effects. A key feature of positive feedback is thus that small disturbances get bigger, when a change occurs in a system, positive feedback causes further change, in the same direction. A simple feedback loop is shown in the diagram, if the loop gain AB is positive, a condition of positive or regenerative feedback exists.
If the functions A and B are linear and AB is smaller than unity, the system gain from the input to output is finite
Tuned mass damper
A tuned mass damper, known as a harmonic absorber, is a device mounted in structures to reduce the amplitude of mechanical vibrations. Their application can prevent discomfort, damage, or outright structural failure and they are frequently used in power transmission and buildings. Tuned mass dampers stabilize against violent motion caused by harmonic vibration, a tuned damper reduces the vibration of a system with a comparatively lightweight component so that the worst-case vibrations are less intense. An example of the latter is a crankshaft torsional damper, Mass dampers are frequently implemented with a frictional or hydraulic component that turns mechanical kinetic energy into heat, like an automotive shock absorber. An electrical analogue is an LCR circuit, given a motor with mass m 1 attached via motor mounts to the ground, the motor vibrates as it operates and the soft motor mounts act as a parallel spring and damper, k 1 and c 1. The force on the motor mounts is F0. In order to reduce the force on the motor mounts as the motor operates over a range of speeds, a smaller mass, m 2, is connected to m 1 by a spring. F1 is the force on the motor due to its operation.
The graph shows the effect of a mass damper on a simple spring–mass–damper system, excited by vibrations with an amplitude of one unit of force applied to the main mass. An important measure of performance is the ratio of the force on the mounts to the force vibrating the motor. This assumes that the system is linear, so if the force on the motor were to double, the blue line represents the baseline system, with a maximum response of 9 units of force at around 9 units of frequency. The red line shows the effect of adding a tuned mass of 10% of the baseline mass and it has a maximum response of 5.5, at a frequency of 7. As a side effect, it has a normal mode and will vibrate somewhat more than the baseline system at frequencies below about 6. The heights of the two peaks can be adjusted by changing the stiffness of the spring in the mass damper. Changing the damping changes the height of the peaks, in a complex fashion, the split between the two peaks can be changed by altering the mass of the damper.
The Bode plot is complex, showing the phase and magnitude of the motion of each mass. In the plots at right, the line shows the baseline response. Now considering m 2 = m 1 /10, the line shows the motion of the damping mass
National Exhibition Centre
The National Exhibition Centre is an exhibition centre located in Birmingham, England. It is near junction 6 of the M42 motorway, and is adjacent to Birmingham Airport and it has 20 interconnected halls, set in grounds of 611 acres making it the largest exhibition centre in the UK. It is the busiest and seventh-largest exhibition centre in Europe, opened by Elizabeth II in February 1976, the first event to be staged at the venue was International Spring Fair, which has returned every year since. Growing annually, the event now occupies all of the NECs 20 halls, in November 1971, the Secretary of State for the Environment granted outline planning approval for the National Exhibition Centre in Birmingham. The NEC, originally comprising 89,000 m2 of exhibition space, was opened by the Queen on 2 February 1976, the building was designed by Edward Mills. In 1989, the Queen opened three further halls, increasing the space to 125,000 m2, four more halls were added in 1993, the total exhibition space increasing to 158,000 m2.
Another four new halls, opened in September 1998 by Neil Kinnock, European Commissioner for Transport and these buildings were designed by Seymour Harris. The NEC is nearing completion of a five-year, £40 million venue improvement programme which has seen improvements made to everything from the car parking to signage and catering. The most obvious result of development has been the redesign of the Piazza – the central space around Halls 1 to 5. The NEC was home to the British International Motorshow from 1978 to 2004, in addition, it hosted the Classic Motor Show. Since 1991, the NEC has been the venue for the dog show Crufts. Held over four days and using five halls as well as the LG Arena, in May 2013, The National Exhibition Centre announced it would be hosting a series of corporate Christmas parties for the first time. The parties run from 8 to 21 December 2013 and it was the venue for Great Britains Davis Cup match against Holland in 2007. The Genting Arena is part of the complex, the NEC has 29,000 car parking spaces spread around the site, with a shuttle bus service operating to and from the car parks.
Parent company The NEC Group owns and operates the Barclaycard Arena and International Convention Centre, official website The NEC Birmingham Business event calendar
Queue areas are places in which people queue for goods or services. Such a group of people is known as a queue or line, and the people are said to be waiting or standing in a queue or in line, respectively. Examples include checking out groceries or other goods that have collected in a self service shop, in a shop without self-service, at an ATM, at a ticket desk. Queueing is a phenomenon in a number of fields, and has been analysed in the study of queueing theory. In economics, queueing is seen as one way to ration scarce goods, organized queue areas are commonly found at amusement parks. The rides have a number of guests that can be served at any given time. Queues can be found in railway stations to book tickets, at bus stops for boarding, queues are generally found at transportation terminals where security screenings are conducted. Sometimes two people who are split up and each waits in a different line, once it is determined which line is faster. Another arrangement is for everyone to wait in a single line and this is a common setup in banks and post offices.
At the beginning of the Common Era, people attending events simply gathered in mass, after several thousand years of this they slowly gravitated to the back of individual fellows, and began to stand behind one another forming what is now colloquially referred to as The Line. Physical queueing is sometimes replaced by virtual queueing, in a waiting room there may be a system whereby the queuer asks and remembers where his place is in the queue, or reports to a desk and signs in, or takes a ticket with a number from a machine. Especially in the United Kingdom, tickets are taken to form a queue at delicatessens and childrens shoe shops. In some countries such as Sweden, virtual queues are common in shops. A display sometimes shows the number that was last called for service, restaurants have come to employ virtual queueing techniques with the availability of application-specific pagers, which alert those waiting that they should report to the host to be seated. Another option used at restaurants is to assign customers a confirmed return time, virtual queueing apps are available that allow the customers to view the virtual queue status of a business and they can take virtual queue numbers remotely.
The app can be used to get updates of the virtual queue status that the customer is in, all of the above methods, suffer from the same drawback, the person arrives at the location only to find out that they need to wait. This has the advantage of allowing users to find out the wait forecast and get in the queue before arriving, roaming freely and this has been shown to extend the patience of those in the queue and reduce no-shows. When designing queues, planners attempt to make the wait as pleasant and they employ several strategies to achieve this, Expanding the capacity of the queue, thus allowing more patrons to have a place
Port of London Authority
The Port of London Authority is a self-funding public trust established by The Port of London Act 1908 to govern the Port of London. Its responsibility extends over the Tideway of the River Thames and its continuation and it maintains and supervises navigation, and protects the rivers environment. The PLA originally operated all enclosed dock systems on the river, but these have long closed to commercial traffic, with the exception of Port of Tilbury. The PLAs responsibility extends from a point marked by an obelisk just downstream of Teddington Lock to the end of the Kent/Essex strait of the North Sea a total of about 95 miles, the PLA does not cover the Medway or the Swale. From the City of London, via the Thames Conservancy, the PLA has inherited ownership of the bed of the river and foreshore from Teddington to the Yantlet Line. During much of the 20th century the PLA owned and operated many of the docks and wharfs in the Port, but they have all now been either closed or privatised. Today the PLA acts mainly as an authority for the tidal stretch of the River Thames, ensuring safe navigation.
Comparable responsibilities for the river including, and upstream of, Teddington Lock fall to the Environment Agency, the PLA is responsible for the operation of Richmond Lock, but it is not responsible for the Thames Barrier which is managed by the Environment Agency in its flood management role. The PLA originally had its headquarters on Tower Hill in the City of London, the PLA retains a presence in the City in offices at Bakers Hall on Harp Lane, where the Chairman, Chief Executive and Secretary of the PLA are based. Both Port Control centres operate the system for coordinating traffic within the PLAs area. The system involves 16 radar stations along the river and out in the estuary, the PLA owns Denton Wharf and Jetty in Gravesend, which is the main base for its fleet of more than 40 vessels. It provides lift-out and maintenance services for users of the Thames. The PLA owns Barrier Gardens Pier and Unity House, near its centre at the Thames Barrier. There are two stations at Harwich and Ramsgate, beyond the estuary and the Port of London.
From these stations pilots are sent out and return from large vessels entering and leaving the Port, the PLA employs about 360 people. The PLA owns three piers and jetties on the River Thames and these are available for other river users as well as the PLAs own vessels. Five new patrol vessels were built by Alnmaritec in Northumberland and delivered in 2009, the Lord Mayor of London, the chief dignitary of the City of London, is ex officio the Admiral of the Port of London. The PLA uses a blue ensign with a gold heraldic sealion on all its vessels and it has a house flag and pennants for the use of the Chairman and the Vice Chairman of its Board
London /ˈlʌndən/ is the capital and most populous city of England and the United Kingdom. Standing on the River Thames in the south east of the island of Great Britain and it was founded by the Romans, who named it Londinium. Londons ancient core, the City of London, largely retains its 1. 12-square-mile medieval boundaries. London is a global city in the arts, education, fashion, healthcare, professional services and development, tourism. It is crowned as the worlds largest financial centre and has the fifth- or sixth-largest metropolitan area GDP in the world, London is a world cultural capital. It is the worlds most-visited city as measured by international arrivals and has the worlds largest city airport system measured by passenger traffic, London is the worlds leading investment destination, hosting more international retailers and ultra high-net-worth individuals than any other city. Londons universities form the largest concentration of education institutes in Europe. In 2012, London became the first city to have hosted the modern Summer Olympic Games three times, London has a diverse range of people and cultures, and more than 300 languages are spoken in the region.
Its estimated mid-2015 municipal population was 8,673,713, the largest of any city in the European Union, Londons urban area is the second most populous in the EU, after Paris, with 9,787,426 inhabitants at the 2011 census. The citys metropolitan area is the most populous in the EU with 13,879,757 inhabitants, the city-region therefore has a similar land area and population to that of the New York metropolitan area. London was the worlds most populous city from around 1831 to 1925, Other famous landmarks include Buckingham Palace, the London Eye, Piccadilly Circus, St Pauls Cathedral, Tower Bridge, Trafalgar Square, and The Shard. The London Underground is the oldest underground railway network in the world, the etymology of London is uncertain. It is an ancient name, found in sources from the 2nd century and it is recorded c.121 as Londinium, which points to Romano-British origin, and hand-written Roman tablets recovered in the city originating from AD 65/70-80 include the word Londinio. The earliest attempted explanation, now disregarded, is attributed to Geoffrey of Monmouth in Historia Regum Britanniae and this had it that the name originated from a supposed King Lud, who had allegedly taken over the city and named it Kaerlud.
From 1898, it was accepted that the name was of Celtic origin and meant place belonging to a man called *Londinos. The ultimate difficulty lies in reconciling the Latin form Londinium with the modern Welsh Llundain, which should demand a form *lōndinion, from earlier *loundiniom. The possibility cannot be ruled out that the Welsh name was borrowed back in from English at a date, and thus cannot be used as a basis from which to reconstruct the original name. Until 1889, the name London officially applied only to the City of London, two recent discoveries indicate probable very early settlements near the Thames in the London area
Southwark Bridge is an arch bridge in London, for traffic linking the district of Southwark and the City across the River Thames. It has the lowest traffic utilisation of any bridge in central London, a previous bridge, designed by John Rennie, opened on the site in 1819 and was originally known as Queen Street Bridge, as shown on the 1818 John Snow Map of London. The bridge consisted of three large cast-iron spans supported by granite piers, the bridge was notable for having the longest cast iron span,240 feet, ever made. A new bridge on the site was designed by Ernest George and it was built by Sir William Arrol & Co. and opened in 1921. The bridge is owned and maintained by Bridge House Estates, a charitable trust overseen by the City of London Corporation, the current bridge was given Grade II listed structure status in 1995. The south end is near the Tate Modern, the Clink Prison Museum, the Globe Theatre, below the bridge on the south side are some old steps, which were once used by Thames watermen as a place to moor their boats and wait for customers.
Below the bridge on the side is a pedestrian tunnel, part of the Queens Walk Embankment. Southwark Bridge appears in films, including Harry Potter and the Order of the Phoenix. The cream painted houses on the side of the bridge, Anchor Terrace. In the 1964 Disney film Mary Poppins, the Banks family mistakenly think that George W. Banks has committed suicide by jumping off the bridge after he is fired from his job at the bank, Southwark Bridge at Structurae Southwark Bridge at Structurae
Sir Robert McAlpine
Sir Robert McAlpine is a private British company headquartered in Hertfordshire. It carries out engineering and construction for the oil and gas, power generation, pharmaceutical, chemical, Sir Robert McAlpine, 1st Baronet who founded the eponymous company was born in 1847 in the Scottish village of Newarthill near Motherwell. From the age of seven he worked in the coal mines. Later, working for an engineer, he progressed to being foreman before starting to work on his own account at the age of 22. He had no other than that he could earn himself. From there, McAlpine enjoyed rapid success, the early contracts centred on his own trade of bricklaying, (It was on one of the housing estates he built that he first experimented with using concrete blocks as well as bricks. With the capital he had acquired, McAlpine determined to build a city at Hamilton. Relying now on the income from his estate, McAlpine’s attention moved away from his contracting business towards self-education. However, the financial panic following the collapse of the City of Glasgow Bank in 1878 virtually wiped out McAlpine financially, his mortgages were called in but his debtors did not pay him.
McAlpine’s first large contract was a building for the Singer Manufacturing Company in 1883, almost immediately he faced further financial difficulties. Winning a contract for the Lanarkshire and Ayrshire Railway without the technical knowledge. Undaunted by his experience, McAlpine took on further railway contracts, this time successfully, including the Mallaig Extension Railway. There was a wide range of building and civil engineering contracts. It was argued that this led to a more cautious approach to risk on the part of the sons – if not the father. The inter-war period saw the firm focusing solely on construction. Gray wrote that Sir Robert McAlpine “seemed to have involved in every major building and civil engineering project that ever hit the headlines of the day. ”They included docks, power stations, the Wembley Stadium. The Dorchester was of particular interest, when the client was unable to pay for the construction works, the company took possession of the completed building and operated it on its own account.
In November 1934, Sir Robert died aged 87, two weeks the eldest son, the new Sir Robert, died
City of London School
It is the brother school of the City of London School for Girls and a member of the Headmasters and Headmistresses Conference. The School was founded by a private Act of Parliament in 1834, the original school was established at Milk Street, moving to the Victoria Embankment in 1879 and its present site on Queen Victoria Street in 1986. The school provides day education to about 900 boys aged 10 to 18 and employs approximately 100 teaching staff, the majority of pupils enter at 11, some at 13 and some at 16 into the Sixth form. There is an intake at 10 into Old Grammar, a year group consisting of two classes equivalent to primary school Year 6. Admissions are based on an examination and an interview. Among Old Citizens who have attained eminence in fields are prime minister H. H. The City of London School traces its origins to a bequest of land by John Carpenter, on his death in 1442, it was found that Carpenter had listed many bequests, most to his relatives but some to charitable causes. There were no bequests listed to directly support the education of boys in the City of London, until they be preferred, and others in their places for ever.
The four boys became known as Carpenters Children, little is known of the early years of the legacy. This bequest was administered by the Corporation of London in around 1460, in 1547, under the Chantries Act the Guildhall Chapel and Library were forfeited. The funding for the four boys was discontinued, in 1823, a report published by the Charity Commission revealed that over the centuries, the income from the bequest vastly exceeded the expenses of the boys education. Had the Corporation instead looked for the will of John Don, lacking that guidance, discussions began on how the bequest money should be spent. The City Lands Committee suggested in a report that the bequest should be spent on educating a number of boys. In 1830, they proposed that the City of London Corporation School be founded with Taylor as a governor, in the mean time, a small number of boys, who became known as Carpenters scholars, were sent to Tonbridge School. In 1829, an Act of Parliament was passed to transform the workhouse into a school, conditions at the workhouse site had deteriorated and much money was needed for its maintenance.
The only funds available, were the same £300 a year budget the workhouse had received. Over the next few years, the proposal was seen, by the City of London Lord Mayors deputation. In 1832, Warren Stormes Hale, who believed that the Workhouse proposal was not the best use of Carpenters legacy, was appointed to the City Lands Committee