Shanghai is one of the four municipalities under the direct administration of the central government of the People's Republic of China, the largest city in China by population, the second most populous city proper in the world, with a population of 24.18 million as of 2017. It is a transport hub, with the world's busiest container port. Located in the Yangtze River Delta, it sits on the south edge of the estuary of the Yangtze in the middle portion of the East China coast; the municipality borders the provinces of Jiangsu and Zhejiang to the north and west, is bounded to the east by the East China Sea. As a major administrative and trading city, Shanghai grew in importance in the 19th century due to trade and recognition of its favourable port location and economic potential; the city was one of five treaty ports forced open to foreign trade following the British victory over China in the First Opium War. The subsequent 1842 Treaty of Nanking and 1844 Treaty of Whampoa allowed the establishment of the Shanghai International Settlement and the French Concession.
The city flourished as a centre of commerce between China and other parts of the world, became the primary financial hub of the Asia-Pacific region in the 1930s. During the World War II, the city was the site of the major Battle of Shanghai. After the war, with the Communist Party takeover of the mainland in 1949, trade was limited to other socialist countries, the city's global influence declined. In the 1990s, the economic reforms introduced by Deng Xiaoping resulted in an intense re-development of the city, aiding the return of finance and foreign investment to the city, it has since re-emerged as a hub for international finance. Shanghai has been described as the "showpiece" of the booming economy of mainland China; the two Chinese characters in the city's name are 上 and 海, together meaning "Upon-the-Sea". The earliest occurrence of this name dates from the 11th-century Song dynasty, at which time there was a river confluence and a town with this name in the area. There are disputes as to how the name should be understood, but Chinese historians have concluded that during the Tang dynasty Shanghai was on the sea.
Shanghai is abbreviated 沪 in Chinese, a contraction of 沪渎, a 4th- or 5th-century Jin name for the mouth of Suzhou Creek when it was the main conduit into the ocean. This character appears on all motor vehicle license plates issued in the municipality today. Another alternative name for Shanghai is Shēn or Shēnchéng, from Lord Chunshen, a 3rd-century BC nobleman and prime minister of the state of Chu, whose fief included modern Shanghai. Sports teams and newspapers in Shanghai use Shen in their names, such as Shanghai Shenhua F. C. and Shen Bao. Huating was another early name for Shanghai. In AD 751, during the mid-Tang dynasty, Huating County was established by the Governor of Wu Commandery Zhao Juzhen at modern-day Songjiang, the first county-level administration within modern-day Shanghai. Today, Huating appears as the name of a four-star hotel in the city; the city has various nicknames in English, including "Pearl of the Orient" and "Paris of the East". During the Spring and Autumn period, the Shanghai area belonged to the Kingdom of Wu, conquered by the Kingdom of Yue, which in turn was conquered by the Kingdom of Chu.
During the Warring States period, Shanghai was part of the fief of Lord Chunshen of Chu, one of the Four Lords of the Warring States. He ordered the excavation of the Huangpu River, its former or poetic name, the Chunshen River, gave Shanghai its nickname of "Shēn". Fishermen living in the Shanghai area created a fish tool called the hù, which lent its name to the outlet of Suzhou Creek north of the Old City and became a common nickname and abbreviation for the city. During the Tang and Song dynasties, Qinglong Town in modern Qingpu District was a major trading port. Established in 746, it developed into what contemporary sources called a "giant town of the Southeast", with thirteen temples and seven pagodas; the famous Song scholar and artist Mi Fu served as its mayor. The port had a thriving trade with provinces along the Yangtze River and the Chinese coast, as well as foreign countries such as Japan and Silla. By the end of the Song dynasty, the center of trading had moved downstream of the Wusong River to Shanghai, upgraded in status from a village to a market town in 1074, in 1172 a second sea wall was built to stabilize the ocean coastline, supplementing an earlier dike.
From the Yuan dynasty in 1292 until Shanghai became a municipality in 1927, central Shanghai was administered as a county under Songjiang Prefecture, whose seat was at the present-day Songjiang District. Two important events helped promote Shanghai's development in the Ming dynasty. A city wall was built for the first time in 1554 to protect the town from raids by Japanese pirates, it measured 10 metres high and 5 kilometres in circumference. During the Wanli reign, Shanghai received an important psychological boost from the erection of a City God Temple in 1602; this honour was reserved for prefectural capitals and not given to a mere county seat such as Shang
Guangzhou known as Canton, is the capital and most populous city of the province of Guangdong in southern China. On the Pearl River about 120 km north-northwest of Hong Kong and 145 km north of Macau, Guangzhou has a history of over 2,200 years and was a major terminus of the maritime Silk Road, continues to serve as a major port and transportation hub, as well as one of China's three largest cities. Guangzhou is at the heart of the most-populous built-up metropolitan area in mainland China that extends into the neighboring cities of Foshan, Dongguan and Shenzhen, forming one of the largest urban agglomerations on the planet. Administratively, the city holds sub-provincial status and is one of China's nine National Central Cities. In 2018 year end, the city's expansive administrative area is estimated at 14,904,400 by city authorities, up 3.8% year on year. Guangzhou is ranked as an Alpha global city. There is a increasing number of foreign temporary residents and immigrants from Southeast Asia, the Middle East, Eastern Europe and Africa.
This has led to it being dubbed the "Capital of the Third World". The domestic migrant population from other provinces of China in Guangzhou was 40% of the city's total population in 2008. Together with Shanghai and Shenzhen, Guangzhou has one of the most expensive real estate markets in China. In the late 1990s and early 2000s, nationals of sub-Saharan Africa who had settled in the Middle East and other parts of Southeast Asia moved in unprecedented numbers to Guangzhou, China in response to the 1997/98 Asian financial crisis. Long the only Chinese port accessible to most foreign traders, Guangzhou fell to the British during the First Opium War. No longer enjoying a monopoly after the war, it lost trade to other ports such as Hong Kong and Shanghai, but continued to serve as a major entrepôt. In modern commerce, Guangzhou is best known for its annual Canton Fair, the oldest and largest trade fair in China. For three consecutive years, Forbes ranked Guangzhou as the best commercial city in mainland China.
Guǎngzhōu is the pinyin romanisation of the Chinese name 廣州, simplified in mainland China to 广州 in the 1950s. The name of the city is taken from the ancient Guang Province, after it had become the prefecture's seat of government, how some other Chinese cities, including Hangzhou and Fuzhou got their names; the character 廣 or 广—which appears in the names of the provinces Guangdong and Guangxi, together called the Liangguang—means "broad" or "expansive" and refers to the intention to dispense imperial grace broadly in the region with the founding of county of Guangxin in Han Dynasty. Before acquiring its current name, the town was known as Panyu, a name still borne by one of Guangzhou's districts not far from the main city; the origin of the name is still uncertain, with 11 various explanations being offered, including that it may have referred to two local mountains. The city has sometimes been known as Guangzhou Fu or Guangfu after its status as the capital of a prefecture. From this latter name, Guangzhou was known to medieval Persians such as Al-Masudi and Ibn Khordadbeh as Khanfu.
Under the Southern Han, the city was renamed Xingwang. The Chinese abbreviation for Guangzhou is "穗", after its nickname "Rice City"; the city has long borne the nickname City of Rams or City of the Five Rams from the five stones at the old Temple of the Five Immortals said to have been the sheep or goats ridden by the Taoist culture heroes credited with introducing rice cultivation to the area around the time of the city's foundation. The former name "City of the Immortals" came from the same story; the more recent City of Flowers is taken as a simple reference to the area's fine greenery. The English name "Canton" derived from Portuguese Cantão or Cidade de Cantão, a muddling of dialectical pronunciations of "Guangdong". Although it and chiefly applied to the walled city, it was conflated with Guangdong by some authors, it was adopted as the Postal Map Romanization of Guangzhou and remained in common use until the gradual adoption of pinyin. As an adjective, it is still used in describing the people, language and culture of Guangzhou and the surrounding Liangguang region.
The 19th-century name "Kwang-chow foo" derived from Nanjing dialect of Mandarin and the town's status as a prefectural capital. A settlement now known as Nanwucheng was present in the area by 1100 BC; some traditional Chinese histories placed Nanwucheng's founding during the reign of Ji Yan, king of Zhou from 314–256 BC. It was said to have consisted of little more than a stockade of mud. Panyu was established on the east bank of the Pearl River in 214 BC to serve as a base for the Qin Empire's first failed invasion of the Baiyue lands in southern China. Legendary accounts claimed the soldiers at Panyu were so vigilant that they did not remove their armor for three years. Upon the fall of the Qin, General Zhao Tuo established his own kingdom of Nanyue and made Panyu its capital in 204 BC, it remained independent through the Chu-Han Contention, although Zhao negotiated recognition of his independence in exchange for his nominal submission to the Han in 196 BC. Archaeological evidence shows that Panyu was an expansive commercial centre: in addition to items from central China, archaeologists have found remains originating from Southeast Asia and Africa.
Zhao Tuo was succeeded by Zhao Mo and Zhao Yingqi. Upon Zhao Yingqi's death in
The Hewlett-Packard Company or Hewlett-Packard was an American multinational information technology company headquartered in Palo Alto, California. It developed and provided a wide variety of hardware components as well as software and related services to consumers, small- and medium-sized businesses and large enterprises, including customers in the government and education sectors; the company was founded in a one-car garage in Palo Alto by Bill Hewlett and David Packard, produced a line of electronic test equipment. HP was the world's leading PC manufacturer from 2007 to Q2 2013, at which time Lenovo ranked ahead of HP. HP specialized in developing and manufacturing computing, data storage, networking hardware, designing software and delivering services. Major product lines included personal computing devices and industry standard servers, related storage devices, networking products, software and a diverse range of printers and other imaging products. HP directly marketed its products to households, small- to medium-sized businesses and enterprises as well as via online distribution, consumer-electronics and office-supply retailers, software partners and major technology vendors.
HP had services and consulting business around its products and partner products. Hewlett-Packard company events included the spin-off of its electronic and bio-analytical measurement instruments part of its business as Agilent Technologies in 1999, its merger with Compaq in 2002, the acquisition of EDS in 2008, which led to combined revenues of $118.4 billion in 2008 and a Fortune 500 ranking of 9 in 2009. In November 2009, HP announced the acquisition of 3Com, with the deal closing on April 12, 2010. On April 28, 2010, HP announced the buyout of Inc. for $1.2 billion. On September 2, 2010, HP won its bidding war for 3PAR with a $33 a share offer, which Dell declined to match. Hewlett-Packard spun off its enterprise products and services business as Hewlett Packard Enterprise on November 1, 2015. Hewlett-Packard held onto the PC and printer businesses, was renamed to HP Inc. Bill Hewlett and David Packard graduated with degrees in electrical engineering from Stanford University in 1935; the company originated in a garage in nearby Palo Alto during a fellowship they had with a past professor, Frederick Terman at Stanford during the Great Depression.
They considered Terman a mentor in forming Hewlett-Packard. In 1938, Packard and Hewlett begin part-time work in a rented garage with an initial capital investment of US$538. In 1939 Hewlett and Packard decided to formalize their partnership, they tossed a coin to decide whether the company they founded would be called Hewlett-Packard or Packard-Hewlett. HP incorporated on August 18, 1947, went public on November 6, 1957. Of the many projects they worked on, their first financially successful product, was a precision audio oscillator, the Model HP200A, their innovation was the use of a small incandescent light bulb as a temperature dependent resistor in a critical portion of the circuit, the negative feedback loop which stabilized the amplitude of the output sinusoidal waveform. This allowed them to sell the Model 200A for $89.40 when competitors were selling less stable oscillators for over $200. The Model 200 series of generators continued production until at least 1972 as the 200AB, still tube-based but improved in design through the years.
One of the company's earliest customers was Walt Disney Productions, which bought eight Model 200B oscillators for use in certifying the Fantasound surround sound systems installed in theaters for the movie Fantasia. They worked on counter-radar technology and artillery shell fuses during World War II, which allowed Packard to be exempt from the draft. HP is recognized as the symbolic founder of Silicon Valley, although it did not investigate semiconductor devices until a few years after the "traitorous eight" had abandoned William Shockley to create Fairchild Semiconductor in 1957. Hewlett-Packard's HP Associates division, established around 1960, developed semiconductor devices for internal use. Instruments and calculators were some of the products using these devices. During the 1960s, HP partnered with Sony and the Yokogawa Electric companies in Japan to develop several high-quality products; the products were not a huge success, as there were high costs in building HP-looking products in Japan.
HP and Yokogawa formed a joint venture in 1963 to market HP products in Japan. HP bought Yokogawa Electric's share of Hewlett-Packard Japan in 1999. HP spun off Dynac, to specialize in digital equipment; the name was picked so that the HP logo "hp" could be turned upside down to be a reverse reflect image of the logo "dy" of the new company. Dynac changed to Dymec, was folded back into HP in 1959. HP experimented with using Digital Equipment Corporation minicomputers with its instruments, but after deciding that it would be easier to build another small design team than deal with DEC, HP entered the computer market in 1966 with the HP 2100 / HP 1000 series of minicomputers; these had a simple accumulator-based design, with two accumulator registers and, in the HP 1000 models, two index registers. The series was produced for 20 years, in spite of several attempts to replace it, was a forerunner of the HP 9800 and HP 250 series of desktop and business computers; the HP 3000 was an advanced stack-based design for a business computing server redesigned with RISC technology.
The HP 2640 series of smart and intelligent terminals introduced forms-based interfaces to ASCII terminals, introduced screen labeled functio
Santa Clara, California
Santa Clara is a city in Santa Clara County, California. The city's population was 116,468 as of the 2010 United States Census, making it the ninth-most populous city in the San Francisco Bay Area. Located 45 miles southeast of San Francisco, the city was founded in 1777 with the establishment of Mission Santa Clara de Asís, the eighth of 21 California missions; the city was incorporated in 1852. The mission, the city, the county are all named for Saint Clare of Assisi. Santa Clara is located in the center of Silicon Valley and is home to the headquarters of several high-tech companies such as Intel, it is home to Santa Clara University, the oldest institution of higher learning in the state of California, built around Mission Santa Clara de Asís. Levi's Stadium, the home of the National Football League's San Francisco 49ers, is located in the city. Santa Clara is bordered by San Jose and Cupertino; the first European to visit the valley was José Francisco Ortega in 1769. He found the area inhabited by Native Americans, whom the Spanish called the Costanos, "coast people" known as the Ohlone.
The Spanish began to colonize California with 21 missions and the Mission Santa Clara de Asis was founded in 1777. In 1846, the American flag was raised over Monterey and symbolized the transfer of the sovereignty of the California Republic over to the United States. In 1851, Santa Clara College was established on the grounds of the original Mission. In 1852, Santa Clara was incorporated as a town. For the next century the economy centered on agriculture since orchards and vegetables were thriving in the fertile soil. By the beginning of the 20th century, the population had reached 5,000 and stayed about the same for many years. In 1905, the first public high-altitude flights by humans were made over Santa Clara in gliders designed by John J. Montgomery; the semiconductor industry, which sprouted around 1960, changed the city and surrounding Valley of Heart's Delight. Santa Clara's first medical hospital was built in 1963; this structure, on Kiely Boulevard, was replaced in 2007 with the new Kaiser Permanente medical center located on Lawrence Expressway at Homestead Road.
Santa Clara was home to a major mental health facility, Agnews State Hospital. According to the National Park Service, more than 100 persons were killed at this site in the 1906 earthquake; the site is the former home to Sun Microsystems and is listed in the National Register of Historic Places. Downtown Santa Clara: the 1963 City Council voted to knock down the 8 block grid of downtown area next to Santa Clara University bordered by Lafayette, Benton and Homestead to receive federal funding from Urban Renewal in USA. In 2018 there is a parking lot and Franklin Mall on Washington St with the one state historical building is, Santa Clara Post Office, apartment building, county courthouse, strip mall. Santa Clara is drained by three seasonal creeks, all of which empty into the southern portion of San Francisco Bay. There are some significant biological resources within the city including habitat for the burrowing owl, a species of special concern in California due to reduction in habitat from urban development during the latter 20th century.
This owl uses burrows created by ground squirrels and prefers level grasslands and disturbed areas. According to the United States Census Bureau, the city covers an area of 18.4 square miles, all of it land. Despite being located only 45 miles from San Francisco, Santa Clara's climate is rather distinct—particularly during the summer, when it is warm and sunny, as opposed to the foggy and cool conditions one finds in San Francisco; the average daily temperatures in July range from 82 °F to 53 °F. Winters are mild, with the mean daily temperatures in January ranging from 58 °F to 38 °F. Most of the annual rainfall comes in the winter months; the 2010 United States Census reported that Santa Clara had a population of 116,468. The population density was 6,327.3 people per square mile. The ethnic makeup of Santa Clara was 52,359 White, 3,154 African American, 579 Native American, 43,889 Asian, 651 Pacific Islander, 9,624 from other races, 6,212 from two or more races. Hispanic or Latino of any race were 22,589 persons.
The Census reported that 113,272 people lived in households, 2,860 lived in non-institutionalized group quarters, 336 were institutionalized. There were 43,021 households, out of which 14,477 had children under the age of 18 living in them, 21,817 were opposite-sex married couples living together, 4,081 had a female householder with no husband present, 2,038 had a male householder with no wife present. There were 2,146 unmarried opposite-sex partnerships, 312 same-sex married couples or partnerships. 10,906 households were made up of individuals and 2,945 had someone living alone, 65 years of age or older. The average household size was 2.63. There were 27,936 families; the age distribution of the population was as follows: 24,774 people were under the age of 18, 12,511 people aged 18 to 24, 41,876 people aged 25 to 44, 25,628 people aged 45 to 64, 11,679 people who w
Shenzhen is a major city in Guangdong Province, China. It holds sub-provincial administrative status, with powers less than those of a province. Shenzhen, which follows the administrative boundaries of Bao'an County became a city in 1979, taking its name from the former county town, whose train station was the last stop on the Mainland Chinese section of the railway between Canton and Kowloon. In 1980, Shenzhen was established as China's first special economic zone. Shenzhen's registered population as of 2017 was estimated at 12,905,000. However, the Shenzhen Municipal Party Committee estimates that the population of Shenzhen is about 20 million, due to the large unregistered floating migrant population living in the city. Shenzhen was one of the fastest-growing cities in the world in the 1990s and the 2000s and has been ranked second on the list of ‘top 10 cities to visit in 2019 by Lonely Planet. Shenzhen's cityscape results from its vibrant economy - made possible by rapid foreign investment following the institution of the policy of "reform and opening-up" in 1979.
The city is a leading global technology hub, dubbed by media as the next Silicon Valley. Shenzhen hosts the Shenzhen Stock Exchange as well as the headquarters of numerous multinational companies such as JXD, Hytera, CIMC, SF Express, Shenzhen Airlines, Hasee, Ping An Bank, Ping An Insurance, China Merchants Bank, Tencent, ZTE, Huawei, DJI and BYD. Shenzhen ranks 14th in the 2019 Global Financial Centres Index, it has one of the busiest container ports in the world. The earliest known recorded mention of the name Shenzhen could date from 1410, during the Ming Dynasty. Local Hakka people call the drains in paddy fields “zhen”. Shenzhen means “deep drains” as the area was once crisscrossed with rivers and streams, with deep drains within the paddy fields; the character 圳 is limited in distribution to an area of South China with its most northerly examples in Zhejiang Province which suggests an association with southwards migration during the Southern Song Dynasty. Due to the city's growing economy in the technological industry, the city has been referred by media as "China's Silicon Valley".
The earliest archaeological remains so far unearthed in the Shenzhen area are shards from a site at Xiantouling on Dapeng Bay, dating back to 5000 BC. From the Han dynasty onwards, the area around Shenzhen was a center of the salt monopoly, thus meriting special imperial protection. Salt pans are still visible around the Pearl River area to the west of the city and are commemorated in the name of Yantian District; the settlement at Nantou was the political center of the area from early antiquity. In the year 331 AD, six counties covering most of modern southeastern Guangdong were merged into one province or "jun" named Dongguan with its administrative center at Nantou; as well as being a center of the politically and fiscally critical salt trade, the area had strategic importance as a stopping off point for international trade. The main shipping route to India and the Byzantine Empire started at Guangzhou; as early as the eighth century, chronicles recorded the Nantou area as being a major commercial center, reported that all foreign ships in the Guangzhou trade would stop there.
It was as a naval defense center guarding the southern approaches to the Pearl River. Nantou was a major naval center at the mouth of the Pearl River in the Ming Dynasty. In this capacity it was involved in 1521 in the successful Chinese action against the Portuguese Fleet under Fernão Pires de Andrade; this battle, called the Battle of Tunmen, was fought in the straits between Shekou and Nei Lingding Island. This area was involved in the events surrounding the end of the Southern Song dynasty; the imperial court, fleeing Kublai Khan’s forces, established itself in the Shenzhen area. Lu Xiufu, the then-chief minister, realized all was lost and knew the Mongolian forces would soon take over the area, he preferred suicide instead of the emperor being captured which might have brought shame to the dynasty, he jumped off a cliff with Emperor Bing, aged 7, the last emperor of the Southern Song Dynasty strapped to his back, killing both. In the late 19th century the Chiu or Zhao clan in Hong Kong identified that Chiwan, an area near Shekou as the final resting place of the Emperor and built a tomb for him.
The tomb, since restored, is still at the same location. Contrary to a common misconception of Shenzhen being a fishing village prior to becoming a city, Shenzhen was a regional market town, the county town of Bao'an since 1953. In November 1979, Bao'an County was promoted to prefecture level, directly governed by Guangdong province, it was renamed Shenzhen, after Shenzhen town. The administrative centre of the county stood around present location of the Dongmen. Shenzhen was singled out to be the first of the five Special Economic Zones in May 1980; the SEZ comprised an area of only 327.5 km2 of southern Shenzhen, covering the current Luohu, Futian and Yantian districts. The SEZ was promoted by Deng Xiaoping and created to be an experimental ground for the practice of market capitalism within a community guided by the ideals of "socialism with Chinese characteristics". In 1982 Bao'an County was re-established; the county was converted to become Bao'an District, out of the Special Economic Zone.
Shenzhen was promoted to a Sub-provincial City in March 1983 and w
Beijing romanized as Peking, is the capital of the People's Republic of China, the world's third most populous city proper, most populous capital city. The city, located in northern China, is governed as a municipality under the direct administration of central government with 16 urban and rural districts. Beijing Municipality is surrounded by Hebei Province with the exception of neighboring Tianjin Municipality to the southeast. Beijing is an important world capital and global power city, one of the world's leading centers for politics and business, education, culture and technology, architecture and diplomacy. A megacity, Beijing is the second largest Chinese city by urban population after Shanghai and is the nation's political and educational center, it is home to the headquarters of most of China's largest state-owned companies and houses the largest number of Fortune Global 500 companies in the world, as well as the world's four biggest financial institutions. It is a major hub for the national highway, expressway and high-speed rail networks.
The Beijing Capital International Airport has been the second busiest in the world by passenger traffic since 2010, and, as of 2016, the city's subway network is the busiest and second longest in the world. Combining both modern and traditional architecture, Beijing is one of the oldest cities in the world, with a rich history dating back three millennia; as the last of the Four Great Ancient Capitals of China, Beijing has been the political center of the country for most of the past eight centuries, was the largest city in the world by population for much of the second millennium A. D. Encyclopædia Britannica notes that "few cities in the world have served for so long as the political headquarters and cultural center of an area as immense as China." With mountains surrounding the inland city on three sides, in addition to the old inner and outer city walls, Beijing was strategically poised and developed to be the residence of the emperor and thus was the perfect location for the imperial capital.
The city is renowned for its opulent palaces, parks, tombs and gates. It has seven UNESCO World Heritage Sites—the Forbidden City, Temple of Heaven, Summer Palace, Ming Tombs and parts of the Great Wall and the Grand Canal— all tourist locations. Siheyuans, the city's traditional housing style, hutongs, the narrow alleys between siheyuans, are major tourist attractions and are common in urban Beijing. Many of Beijing's 91 universities rank among the best in China, such as the Peking University and Tsinghua University. Beijing CBD is a center for Beijing's economic expansion, with the ongoing or completed construction of multiple skyscrapers. Beijing's Zhongguancun area is known as China's Silicon Valley and a center of innovation and technology entrepreneurship. Over the past 3,000 years, the city of Beijing has had numerous other names; the name Beijing, which means "Northern Capital", was applied to the city in 1403 during the Ming dynasty to distinguish the city from Nanjing. The English spelling is based on the pinyin romanization of the two characters as they are pronounced in Standard Mandarin.
An older English spelling, Peking, is the postal romanization of the same two characters as they are pronounced in Chinese dialects spoken in the southern port towns first visited by European traders and missionaries. Those dialects preserve the Middle Chinese pronunciation of 京 as kjaeng, prior to a phonetic shift in the northern dialects to the modern pronunciation. Although Peking is no longer the common name for the city, some of the city's older locations and facilities, such as Beijing Capital International Airport, with IATA Code PEK, Peking University, still use the former romanization; the single Chinese character abbreviation for Beijing is 京, which appears on automobile license plates in the city. The official Latin alphabet abbreviation for Beijing is "BJ"; the earliest traces of human habitation in the Beijing municipality were found in the caves of Dragon Bone Hill near the village of Zhoukoudian in Fangshan District, where Peking Man lived. Homo erectus fossils from the caves date to 230,000 to 250,000 years ago.
Paleolithic Homo sapiens lived there more about 27,000 years ago. Archaeologists have found neolithic settlements throughout the municipality, including in Wangfujing, located in downtown Beijing; the first walled city in Beijing was Jicheng, the capital city of the state of Ji and was built in 1045 BC. Within modern Beijing, Jicheng was located around the present Guang'anmen area in the south of Xicheng District; this settlement was conquered by the state of Yan and made its capital. After the First Emperor unified China, Jicheng became a prefectural capital for the region. During the Three Kingdoms period, it was held by Gongsun Zan and Yuan Shao before falling to the Wei Kingdom of Cao Cao; the AD 3rd-century Western Jin demoted the town, placing the prefectural seat in neighboring Zhuozhou. During the Sixteen Kingdoms period when northern China was conquered and divided by the Wu Hu, Jicheng was the capital of the Xianbei Former Yan Kingdom. After China was reunified during the Sui dynasty, Jicheng known as Zhuojun, became the northern terminus of the Grand Canal.
Under the Tang dynasty, Jicheng as Youzhou, served as a military frontier command center. During the An-Shi Rebellion and again amidst the turmoil of the late Tang, local military commanders founded their own shor
Spectroscopy is the study of the interaction between matter and electromagnetic radiation. Spectroscopy originated through the study of visible light dispersed according to its wavelength, by a prism; the concept was expanded to include any interaction with radiative energy as a function of its wavelength or frequency, predominantly in the electromagnetic spectrum, though matter waves and acoustic waves can be considered forms of radiative energy. Spectroscopic data are represented by an emission spectrum, a plot of the response of interest as a function of wavelength or frequency. Spectroscopy in the electromagnetic spectrum, is a fundamental exploratory tool in the fields of physics and astronomy, allowing the composition, physical structure and electronic structure of matter to be investigated at atomic scale, molecular scale, macro scale, over astronomical distances. Important applications arise from biomedical spectroscopy in the areas of tissue analysis and medical imaging. Spectroscopy and spectrography are terms used to refer to the measurement of radiation intensity as a function of wavelength and are used to describe experimental spectroscopic methods.
Spectral measurement devices are referred to as spectrometers, spectrophotometers, spectrographs or spectral analyzers. Daily observations of color can be related to spectroscopy. Neon lighting is a direct application of atomic spectroscopy. Neon and other noble gases have characteristic emission frequencies. Neon lamps use collision of electrons with the gas to excite these emissions. Inks and paints include chemical compounds selected for their spectral characteristics in order to generate specific colors and hues. A encountered molecular spectrum is that of nitrogen dioxide. Gaseous nitrogen dioxide has a characteristic red absorption feature, this gives air polluted with nitrogen dioxide a reddish-brown color. Rayleigh scattering is a spectroscopic scattering phenomenon. Spectroscopic studies were central to the development of quantum mechanics and included Max Planck's explanation of blackbody radiation, Albert Einstein's explanation of the photoelectric effect and Niels Bohr's explanation of atomic structure and spectra.
Spectroscopy is used in physical and analytical chemistry because atoms and molecules have unique spectra. As a result, these spectra can be used to detect and quantify information about the atoms and molecules. Spectroscopy is used in astronomy and remote sensing on Earth. Most research telescopes have spectrographs; the measured spectra are used to determine the chemical composition and physical properties of astronomical objects. One of the central concepts in spectroscopy is its corresponding resonant frequency. Resonances were first characterized in mechanical systems such as pendulums. Mechanical systems that vibrate or oscillate will experience large amplitude oscillations when they are driven at their resonant frequency. A plot of amplitude vs. excitation frequency will have a peak centered at the resonance frequency. This plot is one type of spectrum, with the peak referred to as a spectral line, most spectral lines have a similar appearance. In quantum mechanical systems, the analogous resonance is a coupling of two quantum mechanical stationary states of one system, such as an atom, via an oscillatory source of energy such as a photon.
The coupling of the two states is strongest when the energy of the source matches the energy difference between the two states. The energy of a photon is related to its frequency by E = h ν where h is Planck's constant, so a spectrum of the system response vs. photon frequency will peak at the resonant frequency or energy. Particles such as electrons and neutrons have a comparable relationship, the de Broglie relations, between their kinetic energy and their wavelength and frequency and therefore can excite resonant interactions. Spectra of atoms and molecules consist of a series of spectral lines, each one representing a resonance between two different quantum states; the explanation of these series, the spectral patterns associated with them, were one of the experimental enigmas that drove the development and acceptance of quantum mechanics. The hydrogen spectral series in particular was first explained by the Rutherford-Bohr quantum model of the hydrogen atom. In some cases spectral lines are well separated and distinguishable, but spectral lines can overlap and appear to be a single transition if the density of energy states is high enough.
Named series of lines include the principal, sharp and fundamental series. Spectroscopy is a sufficiently broad field that many sub-disciplines exist, each with numerous implementations of specific spectroscopic techniques; the various implementations and techniques can be classified in several ways. The types of spectroscopy are distinguished by the type of radiative energy involved in the interaction. In many applications, the spectrum is determined by measuring changes in the intensity or frequency of this energy; the types of radiative energy studied include: Electromagnetic radiation was the first source of energy used for spectroscopic studies. Techniques that employ electromagnetic radiation are classified by the wavelength region of the spectrum and include microwave, terahe