Tracking Real GDP over Time

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DISSERTATIONOFDM Multi-User CommunicationOver Time-Variant Channelsausgef¨uhrt zum Zwecke der Erlangung des akademischen Gradeseines Doktors der technischen Wissenschafteneingereicht an derTechnischen Universit¨at WienFakult¨at f¨ur Elektrotechnik und InformationstechnikvonDipl.-Ing. Thomas ZemenMaurer Lange Gasse 87/2, 1230 Wiengeboren in M¨odling am 20. J¨anner 1970Matrikelnr. 8925585Wien, im July 2004 . SupervisorProf. Ernst BonekInstitut f¨ur Nachrichtentechnik und HochfrequenztechnikTechnische Universit¨at WienExaminerProf. Markus RuppInstitut f¨ur Nachrichtentechnik und HochfrequenztechnikTechnische Universit¨at Wien KurzfassungDie Verf¨ugbarkeit hoher Datenraten f¨ur mobile Teilnehmer ist eine der wichtig-sten Eigenschaften zuk¨unftiger Mobilfunksysteme. Wir untersuchen ein MC-CDMA(multi-carrier code division multiple access) System bei dem eine OFDM (orthogonalfrequency division multiplexing) basierte Mehrtr¨ager¨ubertragung mit der Spreizungder Datensymbol im Frequenzbereich verbunden wird. Die Spreizsequenz dient zurIdentifikation der Benutzer und erm¨oglicht die Ausn¨utzung der Mehrwegediversit¨atdes Mobilfunkkanals. Die¨Ubertragung ist blockorientiert, wobei sich ein Block ausOFDM Pilot- und OFDM Datensymbolen zusammensetzt.F¨ur Schrittgeschwindigkeit kann der Mobilfunkkanal als konstant f¨ur die Dauereines Datenblocks modelliert werden. Wir verwenden ein iteratives Mehrbenutzerde-tektionsverfahren. Hierbei werden Softsymbole aus den Ausgangsdaten des Dekodersgewonnenen. Mittels dieser Softsymbole kann die Interferenz, die durch an-dere Benutzer verursacht wird, reduziert werden. Wir entwickeln ein iterativesKanalsch¨atzverfahren das die zur¨uckgef¨uhrten Softsymbole zur Verbesserung derKanalsch¨atzung verwendet. Die Bitfehlerrate des iterativen Empf¨angers kommtder Einbenutzergrenze nahe. Die Einbenutzergrenze ist die Bitfehlerrate die derEmpf¨anger f¨ur einen einzelnen Benutzer und bei perfekter Kanalkenntnis erreicht.Zur weiteren Verbesserung der Kanalsch¨atzung n¨utzen wir den gesch¨atzten Mit-telwert und die gesch¨atzte Varianz der Softsymbole. Diese Informationen k¨onnenaus den Dekoderausgangsdaten abgeleitet werden da die Datensymbole aus einemAlphabet mit konstantem Betrag stammen. Die iterative Kanalsch¨atzung die dieseInformationen zur Minimierung des quadratischen Fehlers (MMSE, minimum meansquare error) n¨utzt, f¨uhrt zu verbesserter Konvergenz des iterativen Empf¨angers.Bei Fahrzeuggeschwindigkeit ¨andert sich der Kanal signifikant ¨uber die Dauereines Datenblocks. Wir ben¨otigen daher eine ad¨aquate Beschreibung seiner zeitlichenVer¨anderung. Wir untersuchen Algorithmen die den zeitvarianten Kanal sch¨atzenk¨onnen, ohne genaue Information ¨uber seine Statistik zweiter Ordnung zu ben¨otigen.Es wird nur die Kenntnis der maximalen Dopplerbandreite in einem Mobilfunksys-tem, die durch die Tr¨agerfrequenz und die maximale Geschwindigkeit der Benutzerbestimmt ist, angenommen.Wir untersuchen zuerst zeitvariante frequenzflache Kan¨ale und analysieren diev Fourier Basisentwicklung f¨ur die zeitvariante Kanalsch¨atzung. Die Analyse zeigt,dass die Fensterung durch die begrenzte Blockl¨ange zu spektraler Verschmierungf¨uhrt und die beschr¨ankte Dimension der Fourier Basisentwicklung einen Effekt¨ahnlich dem Gibbs Ph¨anomen verursacht. Beide Mechanismen zusammen sind derGrund f¨ur systematische Sch¨atzfehler.Slepians Theorie der zeitkonzentrierten und bandlimitierten Sequenzen er¨offneteinen neuen Ansatz f¨ur die zeitvariante Kanalsch¨atzung. Diese Theorie erm¨oglichtdas Design von doppelt orthogonalen DPS (discrete prolate spheroidal) Sequenzendie an die Datenblockl¨ange und die maximale Dopplerbandbreite angepasst sind. DieDPS Sequenzen werden zur Definition der Slepian Basisentwicklung verwendet. Wirbeweisen analytisch, dass der systematische Sch¨atzfehler der Slepian Basisentwick-lung mindestens eine Zehnerpotenz kleiner ist als der der Fourier Basisentwicklung.Die Tracking Real GDP over Time Tracking Real GDP over Time By: OpenStaxCollege When news reports indicate that “the economy grew 1.2% in the first quarter,” the reports are referring to the percentage change in real GDP By convention, GDP growth is reported at an annualized rate: Whatever the calculated growth in real GDP was for the quarter, it is multiplied by four when it is reported as if the economy were growing at that rate for a full year U.S GDP, 1900–2012 Real GDP in the United States in 2012 was about $13 trillion After adjusting to remove the effects of inflation, this represents a roughly 20-fold increase in the economy’s production of goods and services since the start of the twentieth century (Source: bea.gov) [link] shows the pattern of U.S real GDP since 1900 The generally upward long-term path of GDP has been regularly interrupted by short-term declines A significant decline in real GDP is called a recession An especially lengthy and deep recession is called a depression The severe drop in GDP that occurred during the Great Depression of the 1930s is clearly visible in the figure, as is the Great Recession of 2008–2009 1/4 Tracking Real GDP over Time Real GDP is important because it is highly correlated with other measures of economic activity, like employment and unemployment When real GDP rises, so does employment The most significant human problem associated with recessions (and their larger, uglier cousins, depressions) is that a slowdown in production means that firms need to lay off or fire some of the workers they have Losing a job imposes painful financial and personal costs on workers, and often on their extended families as well In addition, even those who keep their jobs are likely to find that wage raises are scanty at best—or they may even be asked to take pay cuts [link] lists the pattern of recessions and expansions in the U.S economy since 1900 The highest point of the economy, before the recession begins, is called the peak; conversely, the lowest point of a recession, before a recovery begins, is called the trough Thus, a recession lasts from peak to trough, and an economic upswing runs from trough to peak The movement of the economy from peak to trough and trough to peak is called the business cycle It is intriguing to notice that the three longest trough-to-peak expansions of the twentieth century have happened since 1960 The most recent recession started in December 2007 and ended formally in June 2009 This was the most severe recession since the Great Depression of the 1930’s U.S Business Cycles since 1900(Source: http://www.nber.org/cycles/main.html) Trough Peak Months of Contraction Months of Expansion December 1900 September 1902 18 21 August 1904 May 1907 23 33 June 1908 January 1910 13 19 January 1912 January 1913 24 12 December 1914 August 1918 23 44 March 1919 January 1920 10 July 1921 May 1923 18 22 July 1924 October 1926 14 27 November 1927 August 1929 23 21 March 1933 May 1937 43 50 June 1938 February 1945 13 80 October 1945 November 1948 37 2/4 Tracking Real GDP over Time Trough Peak Months of Contraction Months of Expansion October 1949 July 1953 11 45 May 1954 August 1957 10 39 April 1958 April 1960 24 February 1961 December 1969 10 106 November 1970 November 1973 11 36 March 1975 January 1980 16 58 July 1980 July 1981 12 16 92 November 1982 July 1990 March 2001 November 2001 December 2007 June 2009 18 120 73 A private think tank, the National Bureau of Economic Research, is the official tracker of business cycles for the U.S economy However, the effects of a severe recession often linger on after the official ending date assigned by the NBER Key Concepts and Summary Over the long term, U.S real GDP have increased dramatically At the same time, GDP has not increased the same amount each year The speeding up and slowing down of GDP growth represents the business cycle When GDP declines significantly, a recession occurs A longer and deeper decline is a depression Recessions begin at the peak of the business cycle and end at the trough Self-Check Questions Without looking at [link], return to [link] If a recession is defined as a significant decline in national output, can you identify any post-1960 recessions in addition to the recession of 2008–2009? (This requires a judgment call.) Two other major recessions are visible in the figure as slight dips: those of 1973–1975, and 1981–1982 Two other recessions appear in the figure as a flattening of the path of real GDP These were in 1990–1991 and 2001 According to [link], how often have recessions occurred since the end of World War II (1945)? 3/4 Tracking Real GDP over Time 11 recessions in approximately 70 years averages about one recession every six years According to [link], how long has the average recession lasted since the end of World War II? The table lists the “Months of Contraction” for each recession Averaging these figures for the post-WWII recessions gives an average duration of 11 months, or slightly ... I NTERNATIONAL J OURNAL OF E NERGY AND E NVIRONMENT Volume 4, Issue 1, 2013 pp.59-72 Journal homepage: www.IJEE.IEEFoundation.org ISSN 2076-2895 (Print), ISSN 2076-2909 (Online) ©2013 International Energy & Environment Foundation. All rights reserved. Changes of temperature data for energy studies over time and their impact on energy consumption and CO 2 emissions. The case of Athens and Thessaloniki – Greece K. T. Papakostas 1 , A. Michopoulos 1 , T. Mavromatis 2 , N. Kyriakis 1 1 Process Equipment Design Laboratory, Mechanical Engineering Department, Energy Division, Aristotle University of Thessaloniki - 54124 Thessaloniki - Greece. 2 Department of Meteorology-Climatology, School of Geology, Faculty of Sciences, Aristotle University of Thessaloniki - 54124 Thessaloniki - Greece. Abstract In steady-state methods for estimating energy consumption of buildings, the commonly used data include the monthly average dry bulb temperatures, the heating and cooling degree-days and the dry bulb temperature bin data. This work presents average values of these data for the 1983-1992 and 1993-2002 decades, calculated for Athens and Thessaloniki, determined from hourly dry bulb temperature records of meteorological stations (National Observatory of Athens and Aristotle University of Thessaloniki). The results show that the monthly average dry bulb temperatures and the annual average cooling degree-days of the 1993-2002 decade are increased, compared to those of the 1983-1992 decade, while the corresponding annual average heating degree-days are reduced. Also, the low temperature bins frequency results decreased in the 1993-2002 decade while the high temperature ones increased, compared to the 1983-1992 decade. The effect of temperature data variations on the energy consumption and on CO 2 emissions of buildings was examined by calculating the energy demands for heating and cooling and the CO 2 emissions from diesel-oil and electricity use of a typical residential building-model. From the study it is concluded that the heating energy requirements during the decade 1993-2002 were decreased, as compared to the energy demands of the decade 1983-1992, while the cooling energy requirements were increased. The variations of CO 2 emissions from diesel oil and electricity use were analog to the energy requirements alterations. The results indicate a warming trend, at least for the two regions examined, which affect the estimation of heating and cooling demands of buildings. It, therefore, seems obvious that periodic adaptation of the temperature data used for building energy studies is required. Copyright © 2013 International Energy and Environment Foundation - All rights reserved. Keywords: Climate change; Cooling; CO 2 emissions; Degree-days; Energy consumption in buildings; Heating; Steady-state methods; Temperature data. 1. Introduction A climate change seems to be in progress and there is strong evidence that it will continue in the forthcoming decades. Obviously, this change affects the temperature Conquest Over Time Shaara, Michael Published: 1956 Categorie(s): Fiction, Science Fiction, Short Stories Source: http://www.gutenberg.org/etext/31652 1 About Shaara: Michael Shaara (June 23, 1928 - May 5, 1988) was an American writer of science fiction, sports fiction, and historical fiction. He was born to Italian immigrant parents (the family name was originally spelled Sciarra, which in Italian is pronounced the same way) in Jersey City, New Jersey, graduated from Rutgers University in 1951, and served as a sergeant in the 82nd Airborne division prior to the Korean War. Before Shaara began selling science fiction stories to fiction magazines in the 1950s, he was an amateur boxer and police officer. He later taught literat- ure at Florida State University while continuing to write fiction. The stress of this and his smoking caused him to have a heart attack at the early age of 36; from which he fully recovered. His novel about the Battle of Gettysburg, The Killer Angels, won the Pulitzer Prize for Fiction in 1975. Shaara died of another heart attack in 1988. Shaara's son, Jeffrey Shaara, is also a popular writer of historical fiction; most notably sequels to his father's best-known novel. His most famous is the prequel to The Killer Angels, Gods and Generals. Jeffrey was the one to finally get Michael's last book, For Love of the Game, published three years after he died. Today there is a Michael Shaara Award for Excellence in Civil War Fiction, established by Jeffrey Shaara, awarded yearly at Gettysburg College. Also available on Feedbooks for Shaara: • The Book (1953) • Wainer (1954) Copyright: Please read the legal notice included in this e-book and/or check the copyright status in your country. Note: This book is brought to you by Feedbooks http://www.feedbooks.com Strictly for personal use, do not use this file for commercial purposes. 2 Transcriber's Note: This etext was produced from Fantastic Universe November 1956. Ex- tensive research did not uncover any evidence that the U.S. copyright on this publication was renewed. 3 When the radiogram came in it was 10:28 ship's time and old 29 was ex- actly 3.4 light years away from Diomed III. Travis threw her wide open and hoped for the best. By 4:10 that same afternoon, minus three burned out generators and fronting a warped ion screen, old 29 touched the at- mosphere and began homing down. It was a very tense moment. Some- where down in that great blue disc below a Mapping Command ship sat in an open field, sending up the beam which was guiding them down. But it was not the Mapping Command that was important. The Mapping Command was always first. What mattered now was to come in second, any kind of second, close or wide, mile or eyelash, but second come hell or high water. The clouds peeled away. Travis staring anxiously down could see nothing but mist and heavy cloud. He could not help sniffing the air and groaning inwardly. There is no smell quite as expensive as that of burned generators. He could hear the Old Man repeating over and over again—as if Allspace was not one of the richest companies in exist- ence—"burned generators, boy, is burned money, and don't you forget it!" Fat chance me forgetting it, Travis thought gloomily, twitching his nos- trils. But a moment later he did. For Diomed III was below him. And Diomed III was an Open Planet. It happened less often, nowadays, that the Mapping Command ran across intelligent life, and it was even less often that the intelligent life was humanoid. But when it happened it was an event to remember. For space travel had brought with it two great problems. The first was Contact, the second was Trade. For many years Man had prohibited con- tact with intelligent humanoids who did not yet have space travel, on the grounds of the much-discussed Maturity Theory. As time went by, however, and humanoid races were discovered which were biologically identical with Proceedings of the 50th Annual Meeting of the Association for Computational Linguistics, pages 259–263, Jeju, Republic of Korea, 8-14 July 2012. c 2012 Association for Computational Linguistics Word Epoch Disambiguation: Finding How Words Change Over Time Rada Mihalcea Computer Science and Engineering University of North Texas rada@cs.unt.edu Vivi Nastase Institute for Computational Linguistics University of Heidelberg nastase@cl.uni-heidelberg.de Abstract In this paper we introduce the novel task of “word epoch disambiguation,” defined as the problem of identifying changes in word us- age over time. Through experiments run us- ing word usage examples collected from three major periods of time (1800, 1900, 2000), we show that the task is feasible, and significant differences can be observed between occur- rences of words in different periods of time. 1 Introduction Most current natural language processing works with language as if it were a constant. This how- ever, is not the case. Language is continually chang- ing: we discard or coin new senses for old words; metaphoric and metonymic usages become so en- grained that at some point they are considered lit- eral; and we constantly add new words to our vocab- ulary. The purpose of the current work is to look at language as an evolutionary phenomenon, which we can investigate and analyze and use when working with text collections that span a wide time frame. Until recently, such task would not have been possible because of the lack of large amounts of non-contemporary data. 1 This has changed thanks to the Google books and Google Ngrams historical projects. They make available in electronic format a large amount of textual data starting from the 17th century, as well as statistics on word usage. We will exploit this data to find differences in word usage across wide periods of time. 1 While the Brown corpus does include documents from dif- ferent years, it is far from the scale and time range of Google books. The phenomena involved in language change are numerous, and for now we focus on word usage in different time epochs. As an example, the word gay, currently most frequently used to refer to a sexual orientation, was in the previous century used to ex- press an emotion. The word run, in the past used in- transitively, has acquired a transitive sense, common in computational circles where we run processes, programs and such. The purpose of the current research is to quan- tify changes in word usage, which can be the ef- fect of various factors: changes in meaning (ad- dition/removal of senses), changes in distribution, change in topics that co-occur more frequently with a given word, changes in word spelling, etc. For now we test whether we can identify the epoch to which a word occurrence belongs. We use two sets of words – one with monosemous words, the other with poly- semous ones – to try and separate the effect of topic change over time from the effect of sense change. We use examples from Google books, split into three epochs: 1800+/-25 years, 1900+/-25, 2000+/- 25. We select open-class words that occur frequently in all these epochs, and words that occur frequently only in one of them. We then treat each epoch as a “class,” and verify whether we can correctly pre- dict this class for test instances from each epoch for the words in our lists. To test whether word usage frequency or sense variation have an impact on this disambiguation task, we use lists of words that have different frequencies in different epochs as well as different polysemies. As mentioned before, we also compare the performance of monosemous –and thus (sensewise) unchanged through time – and polyse- mous words, to verify whether we can in fact predict sense change as opposed to contextual variation. 259 2 Related Work The purpose of this paper is to look at words .. .Tracking Real GDP over Time Real GDP is important because it is highly correlated with other measures of economic activity, like employment and unemployment When real GDP rises, so... of the path of real GDP These were in 1990–1991 and 2001 According to [link], how often have recessions occurred since the end of World War II (1945)? 3/4 Tracking Real GDP over Time 11 recessions... Concepts and Summary Over the long term, U.S real GDP have increased dramatically At the same time, GDP has not increased the same amount each year The speeding up and slowing down of GDP growth represents