text:
List of history journals

This list of history journals presents representative notable academic journals pertaining to the field of history and historiography. It includes scholarly journals listed by journal databases and professional associations such as: JSTOR, Project MUSE, the Organization of American Historians, the American Historical Association, Goedeken (2000), or are published by national or regional historical societies, or by major scholarly publishers (such as Cambridge University Press, Oxford University Press, the University of Chicago Press and Taylor & Francis). It does not include many of the world's 5000 journals devoted to local history or highly specialized topics. This list is a compilation and not one based on an exhaustive examination and judgment of quality.

General history

 * The American Historical Review
 * Annales. Histoire, Sciences sociales
 * Canadian Journal of History/Annales canadiennes d'histoire
 * The English Historical Review
 * The Historian
 * The Historical Journal
 * Historische Zeitschrift
 * History
 * History Compass
 * History Today
 * History Workshop Journal
 * Journal of Interdisciplinary History
 * Past & Present
 * Radical History Review
 * Revue historique
 * Rivista Storica Italiana
 * Studies in People's History

Classical

 * Antiguo Oriente
 * Bryn Mawr Classical Review
 * Historia: Zeitschrift für Alte Geschichte – Revue d'Histoire Ancienne – Journal of Ancient History – Rivista di Storia Antica
 * The Journal of Hellenic Studies

Modern and contemporary

 * Eighteenth-Century Studies
 * The Historical Journal
 * Journal of Contemporary History
 * The Journal of Modern History

Comparative and world

 * Comparative Studies in Society and History
 * Journal of World History

Africa

 * African Archaeological Review
 * African Economic History
 * African Historical Review
 * Afrique & Histoire
 * History in Africa
 * International Journal of African Historical Studies
 * The Journal of African History
 * Journal of Modern African Studies
 * Journal of Southern African Studies
 * Rhodesiana
 * South African Historical Journal
 * Zaïre. Revue Congolaise—Congoleesch Tijdschrift

Egypt

 * Journal of the American Research Center in Egypt
 * Studien zur Altägyptischen Kultur

Asia

 * Asian Survey
 * Central Asian Survey
 * Iranian Studies
 * Journal of American-East Asian Relations
 * Journal of the American Oriental Society
 * The Journal of Asian Studies
 * Journal of the Royal Asiatic Society
 * Modern Asian Studies

East Asia

 * Bulletin of the National Museum of Japanese History
 * Central Asian Survey
 * Chinese Historical Review
 * Early and Medieval Chinese History
 * Journal of Japanese Studies
 * Korean Studies
 * Late Imperial China
 * Monumenta Nipponica
 * Social Science Japan Journal
 * T'oung Pao: International Journal of Chinese Studies

South Asia

 * Indian Economic and Social History Review
 * Indian Historical Review

Southeast Asia

 * Brunei Museum Journal
 * Journal of the Malaysian Branch of the Royal Asiatic Society
 * Journal of Southeast Asian Studies
 * SOAS Bulletin of Burma Research
 * Journal of the Siam Society

Australasia and Oceania

 * Aboriginal History
 * Australian Economic History Review
 * Australian Historical Studies
 * Australian Journal of Politics and History
 * Journal of the Royal Australian Historical Society
 * New Zealand Journal of History
 * Oceania
 * Queensland History Journal
 * Victorian Historical Journal

Europe

 * Contemporary European History
 * European History Quarterly
 * European Review of History: Revue européenne d'histoire
 * Historical Social Research
 * Itinerario

Middle Ages

 * Bibliothèque de l'École des Chartes
 * Early Medieval Europe
 * Journal of Medieval History
 * Reti Medievali Rivista
 * The Medieval Review
 * Speculum: A Journal of Medieval Studies

Britain

 * Albion
 * Anglo-Saxon England
 * Arthuriana
 * British Catholic History
 * The British Journal for the History of Science
 * Britain and the World, formerly British Scholar
 * Cambrian Medieval Celtic Studies
 * Contemporary British History
 * The Economic History Review
 * The English Historical Review
 * History Workshop Journal
 * History: The Journal of the Historical Association
 * Journal of British Studies
 * Journal of Scottish Historical Studies, formerly Scottish Economic and Social History
 * Journal of Victorian Culture
 * Past and Present
 * The Scottish Historical Review
 * Twentieth Century British History
 * Victorian Studies

Regional or local

 * Oxoniensia

Ireland

 * Analecta Hibernica
 * Archivium Hibernicum
 * Clogher Record
 * Collectanea Hibernica
 * Dublin Historical Record
 * Eighteenth-Century Ireland
 * Ériu
 * The Irish Sword, formerly Journal of the Military History Society of Ireland
 * Journal of the Galway Archaeological and Historical Society
 * Journal of the Royal Society of Antiquaries of Ireland
 * Studia Hibernica

Eastern Europe and Balkans

 * Central Asian Survey
 * Contemporary European History
 * Harvard Ukrainian Studies
 * Journal of Baltic Studies
 * Journal of Modern Greek Studies
 * Journal of Slavic Military Studies
 * Kritika: Explorations in Russian and Eurasian History
 * Kwartalnik Historyczny
 * Prispevki za novejšo zgodovino
 * Revolutionary Russia
 * Russian History
 * Slavic Review
 * Slavonic and East European Review
 * Soviet Studies
 * The Polish Review
 * The Russian Review
 * The Slavic and East European Journal
 * Politics, Religion & Ideology (formerly Totalitarian Movements and Political Religions)
 * Zgodovinski časopis

Nordic Europe

 * Historisk Tidskrift (Sweden)
 * Historisk Tidskrift för Finland
 * Historisk Tidsskrift (Denmark)
 * Historisk Tidsskrift (Norway)
 * Saga (Iceland)
 * Nordic Historical Review
 * Scandinavian Journal of History

Western Europe

 * BMGN: Low Countries Historical Review
 * Bulletin for Spanish and Portuguese Historical Studies
 * Central European History
 * Dutch Crossing: Journal of Low Countries Studies
 * French Historical Studies
 * French History
 * French Studies
 * German History
 * German Studies Review
 * Historische Zeitschrift
 * Journal of Belgian History

Latin America and the Caribbean

 * Revista do Instituto Histórico e Geográfico Brasileiro
 * Anuario Colombiano de Historia Social y de la Cultura
 * Boletín americanista
 * Revista de Historia Americana y Argentina
 * Hispanic American Historical Review
 * Historia
 * Journal of Latin American Studies
 * Mexican Studies/Estudios Mexicanos
 * Revista Complutense de Historia de América

Middle East

 * Ancient Iranian Studies
 * Arabic Sciences and Philosophy
 * Bulletin of the American Schools of Oriental Research
 * Iranian Studies Journal
 * Jerusalem Quarterly
 * Journal of Near Eastern Studies
 * Journal of Palestine Studies
 * Palestine Exploration Quarterly

United States

 * The American Genealogist
 * American Quarterly
 * Arkansas Historical Quarterly
 * Atlanta History: A Journal of Georgia and the South
 * California History
 * The Chronicles of Oklahoma
 * Civil War History
 * Florida Historical Quarterly
 * Georgia Historical Quarterly
 * Harvard Law Review
 * Indiana Magazine of History
 * The Journal of American History (formerly Mississippi Valley Historical Review)
 * Journal of American Studies
 * Journal of the Early Republic
 * Journal of the Gilded Age and Progressive Era
 * Journal of Illinois History
 * Journal of Southern History
 * Journal of the Southwest
 * Journal of the West
 * Kansas History
 * Michigan Historical Review
 * Minnesota History
 * Missouri Historical Review
 * Montana: The Magazine of Western History
 * The New England Quarterly
 * Ohio History
 * Oregon Historical Quarterly
 * Pacific Historical Review
 * Pacific Northwest Quarterly
 * Pennsylvania History: A Journal of Mid-Atlantic Studies
 * Pennsylvania Magazine of History and Biography
 * Reviews in American History
 * William and Mary Quarterly, pre-1815
 * Southwestern Historical Quarterly
 * Virginia Magazine of History and Biography
 * Western Historical Quarterly
 * Wisconsin Magazine of History
 * Yale Law Journal

Canada

 * Acadiensis
 * Canada's History, formerly The Beaver (1920 – 2010)
 * Canadian Historical Review
 * Saskatchewan History

Architectural

 * Change Over Time

Archives

 * American Archivist
 * Archivaria
 * Archives

Business, labor and economics

 * African Economic History
 * Agricultural History
 * Agricultural History Review
 * American Communist History
 * Business History
 * Business History Review
 * Communisme
 * Economic History Review
 * Enterprise and Society
 * Essays in Economic & Business History
 * European Review of Economic History
 * Financial History Review
 * International Labor and Working Class History
 * Journal of Economic History
 * Labor History
 * Labor: Studies in Working-Class History
 * Labour/Le Travail
 * Twentieth Century Communism

Demography and family

 * Continuity and Change: A Journal of Social Structure, Law and Demography in Past Societies
 * Journal of Family History
 * Journal of the History of Childhood and Youth

Environment

 * Environmental History

Ethnic and racial studies

 * Amerasia Journal
 * American Jewish History
 * Australian Journal of Jewish Studies
 * Jewish Social Studies
 * Journal of African American History, formerly The Journal of Negro History (1916–2001)
 * Journal of Asian American Studies

Food history

 * Petits Propos Culinaires
 * Food & History

Genocide

 * Holocaust and Genocide Studies
 * Holocaust Studies: A Journal of Culture and History
 * Journal of Genocide Research

Ideas and historiography

 * History and Theory
 * History of European Ideas
 * Journal of the History of Ideas
 * Social Science History

International relations and diplomatic

 * Diplomatic History
 * Journal of American-East Asian Relations
 * Cold War History
 * Journal of Cold War Studies
 * Journal of Conflict Resolution
 * Journal of Peace Research
 * Prague Papers on the History of International Relations

Legal

 * American Journal of Legal History
 * Revista Chilena de Historia del Derecho

Maritime

 * American Neptune
 * International Journal of Maritime History
 * Mariner's Mirror
 * Northern Mariner

Media and books

 * American Literary History
 * Book History
 * Film & History
 * The Historical Journal of Film, Radio and Television
 * Huntington Library Quarterly

Military

 * Journal of Military History
 * The Journal of Slavic Military Studies
 * Militärgeschichtliche Zeitschrift
 * Journal for the Society of Army Historical Research
 * War in History
 * War & Society

Politics and public policy

 * American Communist History
 * The Journal of Legislative Studies
 * Journal of Policy History
 * Presidential Studies Quarterly
 * The Public Historian

Religion

 * American Jewish History
 * Anglican & Episcopal History
 * Anuario de Historia de la Iglesia
 * Australian Journal of Jewish Studies
 * British Catholic History
 * The Catholic Historical Review
 * Church History
 * History of Religions
 * John Whitmer Historical Association Journal
 * Journal of Ecclesiastical History
 * Journal of Mormon History
 * Journal of Religious History
 * The Mennonite Quarterly Review
 * Mormon Historical Studies
 * Numen
 * Revue d'Histoire Ecclésiastique
 * Reformation

Science and technology

 * Ambix
 * Annals of Science
 * The British Journal for the History of Science
 * Bulletin of the History of Medicine
 * Centaurus
 * Historical Studies in the Natural Sciences
 * History and Technology
 * IEEE Annals of the History of Computing
 * Isis
 * Journal for the History of Astronomy
 * Journal of the History of Medicine and Allied Sciences
 * Notes and Records of the Royal Society
 * Osiris
 * Quest: The History of Spaceflight
 * The Rutherford Journal
 * Technology and Culture

Social

 * Historical Social Research
 * History of Intellectual Culture
 * History Workshop Journal
 * Journal of Social History
 * Social Science History

Teaching and methods

 * The History Teacher
 * American Educational History Journal
 * Programming Historian

Urban

 * Journal of Planning History
 * Journal of Urban History
 * Urban History

Women and gender studies

 * Australian Feminist Studies
 * Aspasia
 * Feminist Studies
 * Gender & History
 * Journal of the History of Sexuality
 * Journal of Women's History

title: List of history journals


text:
Talk:Biology and sexual orientation/Archive 1

I've added some more detail on the LeVay hypothalamus study, which seemed a little sketchily-described before. I hope I haven't made the description too long - if so, someone is welcome to shorten it. Given that this study has been subjected to constant methodological criticisms (try a Google search), it seemed reasonable to discuss some aspects of the methodology, particularly relating to the classification of subjects, in more detail. I've also added information on the similar, more recent study by William Byne and colleagues. I agree with the maveric149 that the current title of the article isn't perfect.

I will add some stuff on twin studies in a few days if I get the time. --EALacey, 14 June 2003

 * The twin studies section is done, though somebody might like to make it a little more concise if they think it's too long. EALacey 11:28 22 Jun 2003 (UTC)

 * Great work! --mav

removed from article:
 * These studies show that there is no scientific data to support a genetic or biologic basis for same-sex attractions.

This statement doesn't logically follow the findings of these studies; which have shown that 1) there is a possible sexual-orientation dimorphism (difference in the size of a part of the brain), 2) the sexual orientation of identical twins seems to follow a predictable pattern once the orientation of one twin is known, and 3) there is a cetain gene that tends to follow individuals who identify as homosexual. --maveric149

In addition, the current title of the article misses the point -- only one of these studies really deals with genetics. The other two deal with phenotypes and behavior -- which arise from varying degrees of interaction between genes, the chemical environment of the body, the outside environment, self-identification, etc. A MUCH better title would be innate basis of sexual orientation. If there is such a thing as a 'gay gene' (or more likely genes) there is every reason to believe that it/they has/have only some degree of influence on sexual orientation that is somehow "set" in early to late adolescence (thus its supposed "innateness"). Many other factors are probably also at play. --maveric149

I agree that the "no data to support" sentence was biased. Thank you for removing it. Readers should be free to draw their own conclusions.

I am open to an improved title, too. I only chose "genetic basis" because that's what the three types of studies seemed to be focusing on, and the words gene and genetic are fairly well-understood to our general readership. I am not sure what innate means.

I contributed the article to shed light on the moral debate over homesexuality by presenting scientific findings related to the contention that adults cannot change their sexual orientation from homosexual to heterosexual. Some (most?) arguments over morality hinge on the aspect of human volition. A person who doesn't realize what he is doing is wrong, or who "can't help it", is judged far more leniently than, say, a murderer in cold blood. Not to say that homosexuality is equivalent to murder, of course! Just that people are only judged on what they can do. A better example might be a vehicle collision. If you didn't see that other car running the red light, you aren't held responsible, whereas if you plainly say the blind person slowly jaywalking across your path in plenty of time to stop, it's a different matter.

I am trying hard to distinguish between advocacy (which I seem to slip into unbeknownst to my self) and providing relevant, useful NPOV articles. I look forward to receiving additional feedback from Maverick and Danny and SR and anyone else who has good ideas on how I can improve my contributions.

Ed Poor, Wednesday, May 8, 2002

It's been almost a year since I wrote this article. Would someone please finish it? At least the twin studies... --Uncle Ed 22:31 Feb 27, 2003 (UTC)

Maybe this research item will help:

 * Gay Gene Isolated, Ostracized

BALTIMORE—On Friday, scientists at Johns Hopkins University isolated the gene which causes homosexuality in human males, promptly separating it from normal, heterosexual genes. "I had suspected that gene was queer for a long time now. There was just something not quite right about it," team leader Dr. Norbert Reynolds said. "It's a good thing we isolated it—I wouldn't want that faggot-ass gene messing with the straight ones." Among the factors Reynolds cited as evidence of the gene's gayness were its pinkish hue, meticulously frilly perimeter, and faint but distinct perfume-like odor.

--Uncle Ed 21:38 Mar 4, 2003 (UTC)

 * Hm. I don't know if I should laugh my gay-ass ass off or be insulted. --mav 23:15 Mar 4, 2003 (UTC)
 * I vote for the first one, though you should promptly reattach it. Tuf-Kat

 * LOL - now that was unquestionably funny. :) --mav

All of this seems to beg the question of whether "homosexuality" is even well-defined, let alone genetically determined. Seems to me that a social construct that has, at most, about 35 years of existence in something like its current form and less than 150 years in any even vaguely resemblant form would not readily expected to be tied to genetics. For example, there is an enormous methodological problem in determining whether a particular person is homosexual. How? Self-description of identity? Self-description of behavior? Controlled study of reaction to images? Is a (behaviorally) bisexual person "homosexual" in this sense? (Thought experiment: was Oscar Wilde a homosexual? How about Virginia Woolf?)

As recently as the 1960s, there was a tendency to count only one partner in many actions we would now call "gay sex" as homosexual. "Trade" were not considered homosexual. In the Spanish-speaking world, much the same obtains even today: a macho guy who has sex with effeminate men is categorized very differently from those effeminate men. With different cultural categories, a biological determinist would go looking for a gene for a different social trait. Why should anyone reasonably expect that this sort of search is any better science than phrenology? Why not expect a gene for monosexuality vs. bisexuality, or for preferring to be on the top during sex? Answer: because they are not comparably important categories in our culture so we don't go looking for them.

I could probably go on at great length, but I hope I've already made myself clear without expanding this into an essay. -- Jmabel 07:49, 5 Feb 2004 (UTC)

 * It is a fallacy to say that just because something is not known of or defined that it does not exist (did most of the elements not exist before they were discovered?). It is also a fallacy to state that something exists just because something is known of or defined (do UFOs exist just because they are known of?). Just because homosexuals have only been out for the last three decades or so does not mean that homosexuality (not just homosexual acts) didn't exist before then (and vice versa).

 * My point is that only sociological and especially biological studies can determine whether or not homosexuality is a new phenomenon or something that has always been with us. Oh and biology and sociology do interact. So if there is such a thing as a genetic predisposition to homosexuality, one would expect to see this acted upon differently in different societies. For example, in many parts of the Mid-East being gay is a capital offense. Needless to say homosexuality is highly repressed in those situations and thus does not appear to exist except as rare abberations. Please don't let past repression of "homosexuals" give you the impression that homosexuality did not exist during far more oppressive times. Let the researchers find this out. --mav 08:39, 5 Feb 2004 (UTC)

Don't get me wrong, I'm sure that some in the past there were a certain number of individuals who conformed reasonably well to our current notion of homosexuality. I'm just saying that there is a long history of searching for, and even seeming to find, scientific evidence for contemporary social contracts. What I am saying is that no one is looking for a genetic predisposition to be "trade", or to be a bondage bottom, or to prefer to wear lavender, because they are not important social categories in our current society. All of these are equally real, or unreal. I view with enormous skepticism any science that claims to validate contemporary social categories. A century ago, scientists were busily validating racial categories that are almost all now considered as lacking scientific validity. -- Jmabel 21:38, 5 Feb 2004 (UTC)

 * ? Different groups of people have different gene pools. Yes we are all remarkably alike for mammals, but there are regional variations (such as average height, skin color, pre-dispostion to certain ailments and abilities, etc.). Just because it is not PC to note these differences does not mean they do not exist (but all such claims need to be taken critically due to past abuse of those type of claims, of course). And please do not confuse 19th century eugenics, phrenology, and social Darwinism quacks with scientists. The comparison by example to current researchers is also a bit off. --mav

Remember that they were not considered quacks in their own time. Yes, different people have different gene pools. There is probably a reasonable biological definition of "Icelanders" or "Ashkenazi", one that would correspond (closely, though not perfectly) with the normal use of the terms. But consider (for example) that there is now known to be more genetic diversity within the "negroid" people than in the entire rest of the human species.

Would you agree that there is sociological rather than a scientific reason that contemporary scientists are looking for genetic "causes" of homosexuality rather than genetic "causes" of (exclusive) heterosexuality? If not, we are so far apart on this that I'll just drop the discussion with you and leave others to form their own conclusions. -- Jmabel 23:40, 5 Feb 2004 (UTC)

 * I agree but your question seems odd: The reason there is a genetic cause of heterosexuality is obvious; since we cannot reproduce asexually at least some men and women need to have sex to propagate the species. And there is a great deal of previous research on that subject and why sexual reproduction evolved in higher taxa and why it has persisted for so long. So some current researchers are investigating questions that do not have clear answers yet. But others continue work on refining answers as to why heterosexuality exists. Their work just doesn't grab headlines. --mav

Certainly. But reproducing doesn't make one a "heterosexual" or, as I remarked above, we'd have to call Oscar Wilde a heterosexual. Ditto Leonard Bernstein. A strong case could be made that heterosexuality, as we now know it, is as much a social construct as homosexuality, as we now know it. -- Jmabel 01:19, 6 Feb 2004 (UTC)

 * By "heterosexuality" I meant "sexual attraction primarily to the opposite sex". That is not a social construct. The reason this is useful in an evolutionary sense is that it encourages reproduction. --mav

Well, obviously. Trivially. But clearly, these studies don't directly study, say, "sexual attraction primarily to the same sex." "Attraction" is very hard to measure. At best they study patterns of actual behavior. At worst they study who-knows-what (e.g. as the article notes in passing, the criteria for the classification of gay and non-gay in LeVay's study seem a bit murky; I make that remark not on the basis of this article but of other things I have read about the study). -- Jmabel 08:59, 6 Feb 2004 (UTC)

homosexuality and natural selection question
I am curious to know if anyone has ever come across any information on the web concerning the genetic basis for homosexuality in light of the generally accepted theory of natural selection. I am writing a short paper on the subject and I am having trouble narrowing my internet searches sufficiently to uncover anything. Basically, my question is this: If a gene for homosexuality exists in the human genome, why has it not been "weeded out" after countless generations in which the most highly reproductive individuals would have been selected for? Obviously homosexuals would have passed on their genes far less frequently than heterosexuals, so how is it that these genes are still present in the human populations of today? Hopefully some of you will know a possible answer to this question or perhaps be able to suggest likely places on the web where I can seek it out myself. I appreciate your time in reading this message.

-Brook
 * I know the "kindly gay uncle" theory has been proposed, meaning that a family member who does not reproduce has the time and resources to help nieces and nephews out, thus propagating his family's genes. Sounds rather dodgy to me, but some people do or have accepted it. Tuf-Kat 18:29, Mar 12, 2004 (UTC)

 * It isn't at all obvious that gay and lesbian people would pass on their genes far less frequently considering the intense pressure to be straight and reproduce over the last few hundred years. Gay people pass on their genes all the time, in fact, gay and lesbian teenagers are twice as likely to impregnate someone or be impregnated (http://www.lesbianinformationservice.org/pregnancy.rtf). See: situational sexual behaviour and causes of sexual orientation. Hyacinth 17:07, 7 Apr 2004 (UTC)

Yes but there is no pressure on animals yet they also show homosexuality. Also a few hundred or even thousand years in nothing in evolutionary terms.

jucifer 19:08, 23 Nov 2004 (UTC)

 * Points taken. However, even without those specific extraordinary pressure(s), gay people are capable of reproduction. Hyacinth 01:09, 24 Nov 2004 (UTC)

Okay, I guess I am someone new to this whole organization, but the most common, and least partisan view that I have found is the idea of "'predisposition'", or increased risk of development through a trait rather than a guaranteed inheritance, it means that people could carry the gene, but never develop homosexual tendencies nor realize that they had the potential to actually be homosexual. Also, it could explain bisexuality, its great prevalence, and how so many people are not pure in their inclined feelings and/or behavior throughout their lives. So for whomever it is who is asking about the "homosexual gene'" may ""predisposition"" possibly serve as a helpful keyword to you.

Also, in the primitve sense(before assistive reproductive technologies), not all people who label themselves "'homosexuals'" only sexually interact with the same sex. There is a difference between taking on an identity as homosexual and being exclusive in sexual behavior, in fact many people in the population are actually bisexual, and not exclusively homosexual.

-Morpheus 2004

What the studies show
Cut from article:

 * These studies lend credence to the idea that there is a genetic component to sexual orientation, or that homosexuality and heterosexuality may be partly the result of some otherwise innate physical characteristic(s).

Actually, this is exactly the opposite of what the studies show. They take away credence from the idea that there is a genetic component to sexual orientation; they don't bolster it at all.

Unscrupulous or careless journalists may have cited these studies, or used selective quotation to make it seem like the studies provided evidence for the "gays are born that way" hypothesis.

But the researchers themselves say that such a conclusion is a misrepresentation. --Uncle Ed 17:19, 6 Apr 2004 (UTC)

From the article:
 * These are theories: hard empirical data is lacking

Shouldn't this be "These are hypotheses"? This article is mostly scientific, and as such should use the scientific definitions of theory/hypothesis, not the popular ones. CyborgTosser 01:42, 13 May 2004 (UTC)

Well, if there's no argument... CyborgTosser 17:54, 28 May 2004 (UTC)

This article is solely devoted to humans. I know a lot of observation has been done on homosexual behaviour in animals, but has any of it been researched in the context of genetics? If so it would make a useful addition to this article. Pcb21| Pete 01:13, 30 Aug 2004 (UTC)

subject -> participant
Apologies to all for the mistaken replacement of 'subject' to 'participant'. Thanks to User:Jmabel for correcting it.

I was replacing 'subjects' with 'participants' in several articles to make them comply with modern thinking and psychology guidelines. The term 'participant' is now commonly regarded as more appropriate than 'subject' when referring to humans that consent to take part in experiments. I was skim reading the articles and did not notice that the humans in the experiments this article were dead. If I had noticed that, I would have left the terms as they were.

In case anyone is interested, examples of the psychology guidelines that mention the use of terms like 'subject' and 'participant' include:
 * The British Psychological Society style guide '10.2 Inappropriate labels'
 * The American Psychological Association (APA) style guide. I understand that the subject/participant issue is in APA 'Chapter 2 Guidelines to Reduce Bias in Language' but I have not read it directly. I undertand that it says something similar to: "Terms like participants,respondents, or students should be used instead of the term, subject". It is referred to in the APA FAQ I've noticed that subjects is often changed in copyediting, most often to participants. Why?

Bobblewik (talk) 09:10, 12 Sep 2004 (UTC)

Argument against a genetic cause
The quote below was added near the top of the article at 05:25, 10 Apr 2004 by 130.235.172.210.
 * A strong argument against a genetic cause, however, is that such genetic variations, which disfavour reproduction in a species would hardly survive a few generations.

I am surprised it has lasted this long unchallenged. It is POV, unscientific (using a similar argument you would expect that we would have no lasting genetic disorders that led to death in childhood) and definitely out of place given that this argument is largely discussed in the conclusions of Twin studies.
 * Any genetic component must be rooted in evolution by natural selection, and many non-scientists assume that a homosexual orientation would necessarily result in decreased reproduction [my bolding]. Gene prevalence, however, and therefore selection, can be influenced by increasing the reproductive success of individuals with whom we share genes in common. While it may be unclear to some how homosexuality could offer a selective advantage to individuals, many hypotheses exist that explain why an inherited tendency toward this orientation might offer a selective advantage to the genes they carry. Most hypotheses speculate that the presence of homosexual members may also promote intragroup harmony. These are hypotheses: hard empirical data is lacking. Apparent homosexual behavior provides a stealth mechanism for slipping past alpha males in some species; like most putative explanations, that does not explain inheritance of female homosexuality. Some twin effects could be the result of their shared environment from conception to birth.

My view would be to simply delete it. Any comments? --CloudSurfer 07:32, 27 Sep 2004 (UTC)

 * I think it's worth (1) keeping this (or something like it), preferably with a citation of someone making this case, (2) characterizing it as a naive objection, and (3) laying out the case, also with citation, for the possible evolutionary value of the "gay uncle". - Jmabel 17:23, Sep 27, 2004 (UTC)

 * My point is that this view is already discussed without citations in the conclusions to the twin studies where it is characterised as coming from "non-scientists". I believe it should be taken out of the lead paragraphs as it is unbalanced in that context and thus misleading. Perhaps the view in the "twin conclusions" could be put with more force. e.g.
 * Any genetic component must be rooted in evolution by natural selection, and many non-scientists assume that a homosexual orientation would necessarily result in decreased reproduction and would thus die out over several generations. ...
 * --CloudSurfer 18:38, 27 Sep 2004 (UTC)

Homosexuality as decoy theory
So, I was bold.

I did not address this theory, though:

 * Apparent homosexual behavior provides a stealth mechanism for slipping past alpha males in some species; like most putative explanations, that does not explain inheritance of female homosexuality.

You might argue that the ability to appear non-competitive to members of the same gender gives advantage, whether male or female. Personally, I find this theory a little badly formed, because it seems more like an evolutionary theory in support of bisexuality, but not purely homosexual attraction, per se. Except perhaps as an maladaptive side-effect. But that doesn't mean that the pros and cons of this idea shouldn't be included in the article. But I'm not sure I have a clear grasp of what people who believe in this theory actually are advocating. Perhaps someone else is more familiary with the theory or there is documentation of the ideas of a popular advocate?

-- Beland 03:18, 28 Sep 2004 (UTC)

Bisexuality and evolution
I mostly agree with this except: "If heterosexuals have an individual reproductive advantage over homosexuals and bisexuals..." Why on earth would being bisexual be any reproductive disadvantage? -- Jmabel 05:22, Sep 28, 2004 (UTC)

 * With a given sex drive, a finite lifetime, and a given population of potential mates and competitors, bisexual creatures would "waste" certain mating opportunities by choosing members of their own gender. (How often that happens depends on the frequency of same-sex choice of mate, and the effects of non-cooperation from heterosexual same-sex partners, probably among other factors.) Over a long period of time, this should result in the heterosexual creatures out-breeding them, all else being equal. -- Beland 06:44, 28 Sep 2004 (UTC)

 * I think that's just silly. What matters for reproductive purposes is how much one breeds with fertile individuals of the opposite sex, not how little other sex one has. By your logic, masturbation would be a reproductive disadvantage, too. -- Jmabel 06:58, Sep 28, 2004 (UTC)

 * In the developed world couples seem to be producing approximately two children per mating pair, give or take minor variances. What is all this nonsense about? Evolution seems to be severely challenged by conscious choice. The vast majority of sexual endeavours end with fun, not fecundity. --CloudSurfer 08:19, 28 Sep 2004 (UTC)

Well, the modern developed world has only existed for a few hundred years, and civilization itself for only a few tens of thousands of years. These are very short periods of time, evolutionarily speaking. The genetic composition of the human race as a whole has not really changed very much since the rise of civilization. So if we are interested in the genetic factors that shape sexual attraction and behavior, then we need to look at evolutionary conditions over the past hundreds of thousands or millions of years.

But it is true that the world has changed a lot since those pre-historic days, and of course putting the same genome in a markedly different environment is going to produce different results.

And of course you are right that conscious choice affects reproduction. Moveover, many evolutionary mechanisms that have been at work for billions of years have in modern times been trumped by human technology and intelligence. But the question we are trying to answer here is not where we will be in million years from now, but how we've gotten to the point we're at now (and more particularly what internal mechanisms we've inherited from the past and how they interact with the modern environment). -- Beland 23:50, 29 Sep 2004 (UTC)

>>What matters for reproductive purposes is how much one breeds with fertile individuals of the opposite sex, not how little other sex one has.<<

Of course. So if we have a bunch of genes that end up causing an organism to have sex with same-sex partners without reducing their mating activities with opposite-sex partners, assuming there are no child-care or survival-rate penalties from any additional time and energy spent doing that, there's no reproductive disadvantage. If, on the other hand, the number of opposite-sex partners or mating events is reduced as a result of partial same-sex attraction, then there will almost certainly be some reproductive disadvantage unless other factors intervene to prevent that from having an impact on number of offspring vs. heterosexual competitors. How the actual genes that actual human bisexuals have inherited which may or may not have some influence on their attraction and behavior are supposed to fit into this picture, is entirely unclear. Which is covered in more detail, I hope, in the discussion on adaptiveness in the article. -- Beland 23:50, 29 Sep 2004 (UTC)

 * Firstly my apologies for using the word "nonsense" which was inappropriate and I thank the anonymous writer for their calm and reasoned response. It should be apparent to anyone who observes animals that mounting behaviour has a percentage of same sex couplings. From my limited personal experience this is true for dogs and cows and I have not personally observed it in other species although I believe there is a literature on this. For instance, I understand that dolphin males at times group in pods and appear to rape other males. So far I have mentioned only social animals and it may well be that there are still "nurture" factors in these despite the apparent lack of language (with the exception of dolphins). The problem is that there is a significant push in the human debate to deny a genetic cause for dogmatic rather than logical reasons and this is what "heated" my response. Again my apologies. --CloudSurfer 05:31, 30 Sep 2004 (UTC)

 * Oh, that was me accidentally mangling my signature (since fixed). "Nurture" is such a broad term, it's often used to include things like environmental conditions and even things like fetal hormone exposure.  Personally, I don't think the world divides up neatly into these two camps, and discussing real-world causes rather than obsessing over how those causes are classified is probably more useful.  But, hey, that's what people seem to like to do.  -- Beland 01:41, 2 Oct 2004 (UTC)

Reorganization
I got a personal request to fix the intro section so that it's no more than three paragraphs or so, to keep the TOC near the top. So I refactored the intro and headerized. Following the general rule of putting layperson-accessible content first in scientific articles, I moved the Politics section up. I also moved the "Twin studies" section up, because this type of study seems to most directly address the question at hand. -- Beland 00:11, 30 Sep 2004 (UTC)

New study
Reported by the BBC today here - http://news.bbc.co.uk/2/hi/health/3735668.stm - may be of interest to the keepers of this article. Pcb21| Pete 08:09, 13 Oct 2004 (UTC)

 * Now integrated into the article. Thanks for pointing this out! -- Beland 06:21, 11 Apr 2005 (UTC)

Disputed
The material in this section appears to be taken largely from a report similar to or perhaps this same one. The current Wikipedia text seems to summarize the BBC report incorrectly in that it conflates two different scientific theories. I will attempt to fix it. -- Beland 05:40, 11 Apr 2005 (UTC)

 * OK, this section now accurately represents my understanding of what the BBC was reporting. It would be very worthwhile to dig up the original studies to make sure what we are reporting accurately represents what the journal articles said. -- Beland 06:20, 11 Apr 2005 (UTC)

HIV/AIDS and brain features

 * Also, HIV/AIDS may affect the brain, causing chemical changes. So rather than showing that differences in neurons indicate homosexuality, LeVay's study may be showing that HIV/AIDS causes differences in neurons. It should be noted, however, that neither LeVay nor Byne found an HIV-related difference in INAH3 size.

I'm wondering whether or not this is a spurious and/or misleading statement. Did LeVay actually check for this? Is this a plausible confounding variable proposed in a scientific journal article, or is this something a random Wikipedian thought up? -- Beland 06:34, 11 Apr 2005 (UTC)

 * This is roughly what LeVay said. He's stated many times that his study proves (though it also doesn't disprove) no correlation between homosexuality and brain structures - there were just too many uncontrolled variables.  -Seth Mahoney 18:37, Apr 11, 2005 (UTC)

Darwinism
I found this in the "Homosexuality" article:

 * Georgetown University explaining the widespread homosexuality and attractions in adolescence has theorized this may be an integral part of bonding to reduce inter-species aggression later in life when many become bisexual.

I couldn't find any more information about this through a quick Google search. It sounds like a dubious theory, but is very likely being misreported here, so I'm removing it until more research on the subject can be done. -- Beland 04:08, 5 May 2005 (UTC)

I think that is there dolphin theory. That is a good question. Should this article also cover sexual orientation in other species? :) Polisci 03:25, 15 August 2005 (UTC)

Pheromones correlation
This section has no citation, and all significant content was anonymously added. Unless there is a citation, I am inclined to remove it: I see no way to identify the study in question, let alone clarify (for example) its methodology for identifying a person as heterosexual or gay. -- Jmabel | Talk 05:12, May 12, 2005 (UTC)

 * Oops! You caught me.  I accidentally deleted the citation when I edited the content to avoid using a direct quote from the aritcle.  -Seth Mahoney 02:32, May 13, 2005 (UTC)

 * I've now added the citation at the bottom of the article, along with the others. -- Jmabel | Talk 01:34, May 14, 2005 (UTC)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text: User talk:69.171.146.13

title: User talk:69.171.146.13


text:
Telus World of Science Edmonton

Telus World of Science Edmonton (TWOSE) is a broad-based science centre in Edmonton, Alberta, Canada, operated by the (non-profit) Edmonton Space & Science Foundation. The centre is located on the southwest corner of Coronation Park in the neighborhood of Woodcroft. The science centre houses 144,430 sq. ft. of public space and is the largest science centre in Western Canada (by largest total public space). It is currently a member of both the Association of Science-Technology Centers (ASTC) and the Canadian Association of Science Centres (CASC).

History
History of the Science Center

1960- The Queen Elizabeth Planetarium, located to the east, operated as the Edmonton's Planetarium, the predecessors to the Edmonton Space Sciences Centre, since 1960 but had become limited by its seating capacity of 65.

1980- The City of Edmonton selected the Edmonton Space Sciences Centre as the City's flagship project commemorating the Province of Alberta's 75th Anniversary. The original building was designed by architect Douglas Cardinal.

1984- The Edmonton Space Sciences Centre opens to the general public

1990- The Edmonton Space Sciences Centre officially changes its name to Edmonton Space and Science Centre

1993- A new expansion adds 15'000 square feet of space split over two floors. Accompanying this expansion, new facilities lobby, Gift Shop, IMAX Theatre entry, Cafe, large gallery for travelling exhibits, and Visitor Services facilities are all added, as well as a refit of old space.

2001- A $14-million expansion was announced with the addition of a new name, the Odyssium.

2005- The Odyssium is renamed the Telus World of Science Edmonton with a sponsorship established with Telus Communications. The centre attracts over half a million visitors annually and has Canada's largest planetarium dome theatre (the Zeidler Dome).

2016- A plan – the Aurora Project – is announced to revamp the science centre. It is budgeted at $41.5 million. The expansion includes:

 * A new DVT (Digital Visualization Theatre).
 * New galleries.
 * An upgraded restaurant.
 * A new front entrance.
 * A new gift shop.

2016-2018- Phases 1 and 2 are complete with a newly refurbished Purple Pear Restaurant, a complete overhaul of the Zeidler Dome and the reimagined S.P.A.C.E. (Stars, Planets, Astronauts, Comets, etc.) Gallery

2018-2022- Phase 3 is completed with the addition of new galleries: Nature Exchange, Curious City, and Health Zone are all redone, and the expansion of the Science Garage was completed

2022-2023- Phase 4 Arctic Expedition and front entrance opens and the Aurora Project is complete

IMAX Theatre
A 275-seat theatre showing current educational movies, shot in high resolution IMAX film reel. The Telus World of Science features the original IMAX Theatre in Western Canada. Images are enhanced by a custom designed six-channel, multi-speaker sound system are projected onto a 13m x 19m (4 storey x 6 storey) screen.

In early 2016, renovations had been completed in the IMAX theatre, upgrading it to an IMAX Laser 4K Projector system (one of 3 theatres in Canada).

Admission to the IMAX theatre is not included with general admission. Recently, the IMAX Theatre began showing Hollywood blockbusters (such as Batman v Superman or Zootopia) within a few months after screening in cinemas. As with the educational films, these are not included in the admission price and can be more expensive than the educational films. The Hollywood films cannot be used in the Science Centre + IMAX combos.

Margaret Zeidler Star Theatre
The 250-seat large dome theatre that was formerly used for laser shows and star shows. It was the largest such theater in Canada when the center opened in 1984. In 2008, the Margaret Zeidler Star Theatre changed its projection system and educational content to a full dome immersive video experience. The Telus World of Science Edmonton was the first planetarium and science center in Canada to showcase this new technology for domed theatres. Admission to shows in the Star Theatre is included in general admission. The Star Theatre is additionally equipped with high powered lasers for weekly laser shows.

Purple Pear and Gift Shop
The science centre has a café for visitors and for special events such as fundraisers. The café was undergoing renovations as of early 2016 with an estimated completion by the end of August 2016, though it was delayed until November 2016. The café is also responsible for providing the concession, which is currently hosted in the main lobby, next to the box office.

In November 2016, the cafe re-opened, but under a new name, The Purple Pear and a new focus on fresher, and local ingredients. They were also the first location in Western Canada to use tagged Coca-Cola Freestyle machines.

There is also a gift shop in the lobby, featuring a range of educational products, books, gift items, and other knick-knacks.

Queen Elizabeth II Planetarium (QEP)- Future
Built in 1959, the Queen Elizabeth Planetarium was the original home of the science centre. The RASC previously ran the QEP from 1960-1983 until the Edmonton Space Science foundation took over soon afterward. In 2016 the City of Edmonton announced plans to restore the planetarium and grant it full heritage status. On July 1st 2023, the QEP was opened to the public and is now operational.

Observatory
Built the same time as the original Edmonton Science Centre, the Observatory opened its doors in 1984. This outdoor structure is located in Coronation Park and It is free of charge, but it opens only when the weather permits, and it closes if the temperature is below -10 C. It is equipped with seven telescopes, including a Meade 16" LX200, a 7 in Starfire refractor, and three solar telescopes all provided by the Royal Astronomical Society of Canada (Edmonton Centre).

title: Telus World of Science Edmonton


text:
File:VerticalManCover.jpg

Fair use in Vertical Man
Though this image is subject to copyright, its use is covered by the U.S. fair use laws because:
 * 1) It's a low resolution copy of a CD/album cover.
 * 2) It doesn't limit the copyright owner's rights to sell the CD/album in any way, in fact, it may encourage sales.
 * 3) Because of the low resolution, copies could not be used to make illegal copies of the album artwork on another CD.
 * 4) The image is itself a subject of discussion in the article or used in the infobox thereof.
 * 5) The image on the cover is significant because it was made by a famous artist.

Source

 * 1) Derived from a digital capture (scan/photo) of the album/CD cover (creator of this digital version is irrelevant as the copyright in all equivalent images is still held by the same party). Copyright held by the record company or the artist. Claimed as fair use regardless.

title: File:VerticalManCover.jpg


text:
Talk:Vuco II

Fair use rationale for Image:Vuco II - front cover.jpg
Image:Vuco II - front cover.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.

BetacommandBot 04:39, 20 July 2007 (UTC)

title: Talk:Vuco II


text:
Talk:Vuco III

Fair use rationale for Image:Vuco III - front cover.jpg
Image:Vuco III - front cover.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.

BetacommandBot 04:39, 20 July 2007 (UTC)

title: Talk:Vuco III


text:
Talk:Vuco IV

Fair use rationale for Image:Vuco IV - front cover.jpg
Image:Vuco IV - front cover.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.

BetacommandBot 04:39, 20 July 2007 (UTC)

title: Talk:Vuco IV


text:
Talk:Volim piti i ljubiti

Fair use rationale for Image:Volim piti i ljubiti - front cover.jpg
Image:Volim piti i ljubiti - front cover.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.

BetacommandBot 14:51, 19 July 2007 (UTC)

title: Talk:Volim piti i ljubiti


text:
Talk:Vuco: najveći hitovi

Fair use rationale for Image:Vuco najveci hitovi - front cover.jpg
Image:Vuco najveci hitovi - front cover.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.

BetacommandBot 04:38, 20 July 2007 (UTC)

title: Talk:Vuco: najveći hitovi


text:
Talk:Vuco 2001

Fair use rationale for Image:Vuco 2001 - front cover.jpg
Image:Vuco 2001 - front cover.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.

BetacommandBot 04:40, 20 July 2007 (UTC)

title: Talk:Vuco 2001


text:
Talk:Vrati se, vrati

Fair use rationale for Image:Vrati se, vrati - front cover.jpg
Image:Vrati se, vrati - front cover.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.

BetacommandBot 04:41, 20 July 2007 (UTC)

title: Talk:Vrati se, vrati


text:
Finite character

In mathematics, a family $$\mathcal{F}$$ of sets is of finite character if for each $$A$$, $$A$$ belongs to  $$\mathcal{F}$$ if and only if every finite subset of $$A$$ belongs to  $$\mathcal{F}$$. That is,
 * 1) For each $$A\in \mathcal{F}$$, every finite subset of $$A$$ belongs to $$\mathcal{F}$$.
 * 2) If every finite subset of a given set $$A$$ belongs to $$\mathcal{F}$$, then $$A$$ belongs to  $$\mathcal{F}$$.

Properties
A family $$\mathcal{F}$$ of sets of finite character enjoys the following properties:

 * 1) For each $$A\in \mathcal{F}$$, every (finite or infinite) subset of $$A$$ belongs to $$\mathcal{F}$$.
 * 2) Every nonempty family of finite character has a maximal element with respect to inclusion (Tukey's lemma): In $$\mathcal{F}$$, partially ordered by inclusion, the union of every chain of elements of $$\mathcal{F}$$ also belongs to $$\mathcal{F}$$, therefore, by Zorn's lemma, $$\mathcal{F}$$ contains at least one maximal element.

Example
Let $$V$$ be a vector space, and let $$\mathcal{F}$$ be the family of linearly independent subsets of $$V$$. Then $$\mathcal{F}$$ is a family of finite character (because a subset $$X \subseteq V $$ is linearly dependent if and only if $$X$$ has a finite subset which is linearly dependent). Therefore, in every vector space, there exists a maximal family of linearly independent elements. As a maximal family is a vector basis, every vector space has a (possibly infinite) vector basis.

title: Finite character


text:
Talk:Volim narodno

Fair use rationale for Image:Volim narodno - front cover.jpg
Image:Volim narodno - front cover.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.

BetacommandBot 14:51, 19 July 2007 (UTC)

title: Talk:Volim narodno


text:
Perlo

Perlo may refer to:

Places

 * Perlo, Piedmont, a comune in the Province of Cuneo, Italy
 * Perlő, the Hungarian name for Brebu Commune, Caraş-Severin County, Romania

People

 * Phil Perlo, American football player
 * Victor Perlo, an American economist

Other uses

 * Perlo group, an American network of Soviet espionage agents

title: Perlo


text:
Thermal power station

A thermal power station is a type of power station in which heat energy is converted to electrical energy. In a steam-generating cycle heat is used to boil water in a large pressure vessel to produce high-pressure steam, which drives a steam turbine connected to an electrical generator. The low-pressure exhaust from the turbine enters a steam condenser where it is cooled to produce hot condensate which is recycled to the heating process to generate more high pressure steam. This is known as a Rankine cycle.

The design of thermal power stations depends on the intended energy source: fossil fuel, nuclear and geothermal power, solar energy, biofuels, and waste incineration are all used. Certain thermal power stations are also designed to produce heat for industrial purposes; for district heating; or desalination of water, in addition to generating electrical power.

Fuels such as natural gas or oil can also be burnt directly in gas turbines (internal combustion). These plants can be of the open cycle or the more efficient combined cycle type.

Types of thermal energy
Almost all coal-fired power stations, petroleum, nuclear, geothermal, solar thermal electric, and waste incineration plants, as well as all natural gas power stations are thermal. Natural gas is frequently burned in gas turbines as well as boilers. The waste heat from a gas turbine, in the form of hot exhaust gas, can be used to raise steam by passing this gas through a heat recovery steam generator (HRSG). The steam is then used to drive a steam turbine in a combined cycle plant that improves overall efficiency. Power stations burning coal, fuel oil, or natural gas are often called fossil fuel power stations. Some biomass-fueled thermal power stations have appeared also. Non-nuclear thermal power stations, particularly fossil-fueled plants, which do not use cogeneration are sometimes referred to as conventional power stations.

Commercial electric utility power stations are usually constructed on a large scale and designed for continuous operation. Virtually all electric power stations use three-phase electrical generators to produce alternating current (AC) electric power at a frequency of 50 Hz or 60 Hz. Large companies or institutions may have their own power stations to supply heating or electricity to their facilities, especially if steam is created anyway for other purposes. Steam-driven power stations have been used to drive most ships in most of the 20th century. Shipboard power stations usually directly couple the turbine to the ship's propellers through gearboxes. Power stations in such ships also provide steam to smaller turbines driving electric generators to supply electricity. Nuclear marine propulsion is, with few exceptions, used only in naval vessels. There have been many turbo-electric ships in which a steam-driven turbine drives an electric generator which powers an electric motor for propulsion.

Cogeneration plants, often called combined heat and power (CHP) facilities, produce both electric power and heat for process heat or space heating, such as steam and hot water.

History
The reciprocating steam engine has been used to produce mechanical power since the 18th century, with notable improvements being made by James Watt. When the first commercially developed central electrical power stations were established in 1882 at Pearl Street Station in New York and Holborn Viaduct power station in London, reciprocating steam engines were used. The development of the steam turbine in 1884 provided larger and more efficient machine designs for central generating stations. By 1892 the turbine was considered a better alternative to reciprocating engines; turbines offered higher speeds, more compact machinery, and stable speed regulation allowing for parallel synchronous operation of generators on a common bus. After about 1905, turbines entirely replaced reciprocating engines in almost all large central power stations.

The largest reciprocating engine-generator sets ever built were completed in 1901 for the Manhattan Elevated Railway. Each of seventeen units weighed about 500 tons and was rated 6000 kilowatts; a contemporary turbine set of similar rating would have weighed about 20% as much.

Thermal power generation efficiency
The energy efficiency of a conventional thermal power station is defined as saleable energy produced as a percent of the heating value of the fuel consumed. A simple cycle gas turbine achieves energy conversion efficiencies from 20 to 35%. Typical coal-based power plants operating at steam pressures of 170 bar and 570 °C run at efficiency of 35 to 38%, with state-of-the-art fossil fuel plants at 46% efficiency. Combined-cycle systems can reach higher values. As with all heat engines, their efficiency is limited, and governed by the laws of thermodynamics.

The Carnot efficiency dictates that higher efficiencies can be attained by increasing the temperature of the steam. Sub-critical pressure fossil fuel power stations can achieve 36–40% efficiency. Supercritical designs have efficiencies in the low to mid 40% range, with new "ultra critical" designs using pressures above 4400 psi and multiple stage reheat reaching 45–48% efficiency. Above the critical point for water of 705 F and 3212 psi, there is no phase transition from water to steam, but only a gradual decrease in density.

Currently most nuclear power stations must operate below the temperatures and pressures that coal-fired plants do, in order to provide more conservative safety margins within the systems that remove heat from the nuclear fuel. This, in turn, limits their thermodynamic efficiency to 30–32%. Some advanced reactor designs being studied, such as the very-high-temperature reactor, Advanced Gas-cooled Reactor, and supercritical water reactor, would operate at temperatures and pressures similar to current coal plants, producing comparable thermodynamic efficiency.

The energy of a thermal power station not utilized in power production must leave the plant in the form of heat to the environment. This waste heat can go through a condenser and be disposed of with cooling water or in cooling towers. If the waste heat is instead used for district heating, it is called cogeneration. An important class of thermal power station is that associated with desalination facilities; these are typically found in desert countries with large supplies of natural gas, and in these plants freshwater production and electricity are equally important co-products.

Other types of power stations are subject to different efficiency limitations. Most hydropower stations in the United States are about 90 percent efficient in converting the energy of falling water into electricity while the efficiency of a wind turbine is limited by Betz's law, to about 59.3%, and actual wind turbines show lower efficiency.

Electricity cost
The direct cost of electric energy produced by a thermal power station is the result of cost of fuel, capital cost for the plant, operator labour, maintenance, and such factors as ash handling and disposal. Indirect social or environmental costs, such as the economic value of environmental impacts, or environmental and health effects of the complete fuel cycle and plant decommissioning, are not usually assigned to generation costs for thermal stations in utility practice, but may form part of an environmental impact assessment. Those indirect costs belong to the broader concept of externalities.

Boiler and steam cycle
In the nuclear plant field, steam generator refers to a specific type of large heat exchanger used in a pressurized water reactor (PWR) to thermally connect the primary (reactor plant) and secondary (steam plant) systems, which generates steam. In a boiling water reactor (BWR), no separate steam generator is used and water boils in the reactor core.

In some industrial settings, there can also be steam-producing heat exchangers called heat recovery steam generators (HRSG) which utilize heat from some industrial process, most commonly utilizing hot exhaust from a gas turbine. The steam generating boiler has to produce steam at the high purity, pressure and temperature required for the steam turbine that drives the electrical generator.

Geothermal plants do not need boilers because they use naturally occurring steam sources. Heat exchangers may be used where the geothermal steam is very corrosive or contains excessive suspended solids.

A fossil fuel steam generator includes an economizer, a steam drum, and the furnace with its steam generating tubes and superheater coils. Necessary safety valves are located at suitable points to protect against excessive boiler pressure. The air and flue gas path equipment include: forced draft (FD) fan, air preheater (AP), boiler furnace, induced draft (ID) fan, fly ash collectors (electrostatic precipitator or baghouse), and the flue-gas stack.

Feed water heating
The boiler feed water used in the steam boiler is a means of transferring heat energy from the burning fuel to the mechanical energy of the spinning steam turbine. The total feed water consists of recirculated condensate water and purified makeup water. Because the metallic materials it contacts are subject to corrosion at high temperatures and pressures, the makeup water is highly purified before use. A system of water softeners and ion exchange demineralizes produces water so pure that it coincidentally becomes an electrical insulator, with conductivity in the range of 0.3–1.0 microsiemens per centimeter. The makeup water in a 500 MWe plant amounts to perhaps 120 US gallons per minute (7.6 L/s) to replace water drawn off from the boiler drums for water purity management, and to also offset the small losses from steam leaks in the system.

The feed water cycle begins with condensate water being pumped out of the condenser after traveling through the steam turbines. The condensate flow rate at full load in a 500 MW plant is about 6,000 US gallons per minute (400 L/s). The water is usually pressurized in two stages, and typically flows through a series of six or seven intermediate feed water heaters, heated up at each point with steam extracted from an appropriate extraction connection on the turbines and gaining temperature at each stage. Typically, in the middle of this series of feedwater heaters, and before the second stage of pressurization, the condensate plus the makeup water flows through a deaerator that removes dissolved air from the water, further purifying and reducing its corrosiveness. The water may be dosed following this point with hydrazine, a chemical that removes the remaining oxygen in the water to below 5 parts per billion (ppb). It is also dosed with pH control agents such as ammonia or morpholine to keep the residual acidity low and thus non-corrosive.

Boiler operation
The boiler is a rectangular furnace about 50 ft on a side and 130 ft tall. Its walls are made of a web of high pressure steel tubes about 2.3 in in diameter.

Fuel such as pulverized coal is air-blown into the furnace through burners located at the four corners, or along one wall, or two opposite walls, and it is ignited to rapidly burn, forming a large fireball at the center. The thermal radiation of the fireball heats the water that circulates through the boiler tubes near the boiler perimeter. The water circulation rate in the boiler is three to four times the throughput. As the water in the boiler circulates it absorbs heat and changes into steam. It is separated from the water inside a drum at the top of the furnace. The saturated steam is introduced into superheat pendant tubes that hang in the hottest part of the combustion gases as they exit the furnace. Here the steam is superheated to 1000 F to prepare it for the turbine.

Plants that use gas turbines to heat the water for conversion into steam use boilers known as heat recovery steam generators (HRSG). The exhaust heat from the gas turbines is used to make superheated steam that is then used in a conventional water-steam generation cycle, as described in the gas turbine combined-cycle plants section.

Boiler furnace and steam drum
The water enters the boiler through a section in the convection pass called the economizer. From the economizer it passes to the steam drum and from there it goes through downcomers to inlet headers at the bottom of the water walls. From these headers the water rises through the water walls of the furnace where some of it is turned into steam and the mixture of water and steam then re-enters the steam drum. This process may be driven purely by natural circulation (because the water is the downcomers is denser than the water/steam mixture in the water walls) or assisted by pumps. In the steam drum, the water is returned to the downcomers and the steam is passed through a series of steam separators and dryers that remove water droplets from the steam. The dry steam then flows into the superheater coils.

The boiler furnace auxiliary equipment includes coal feed nozzles and igniter guns, soot blowers, water lancing, and observation ports (in the furnace walls) for observation of the furnace interior. Furnace explosions due to any accumulation of combustible gases after a trip-out are avoided by flushing out such gases from the combustion zone before igniting the coal.

The steam drum (as well as the superheater coils and headers) have air vents and drains needed for initial start up.

Superheater
Fossil fuel power stations often have a superheater section in the steam generating furnace. The steam passes through drying equipment inside the steam drum on to the superheater, a set of tubes in the furnace. Here the steam picks up more energy from hot flue gases outside the tubing, and its temperature is now superheated above the saturation temperature. The superheated steam is then piped through the main steam lines to the valves before the high-pressure turbine.

Nuclear-powered steam plants do not have such sections but produce steam at essentially saturated conditions. Experimental nuclear plants were equipped with fossil-fired superheaters in an attempt to improve overall plant operating cost.

Steam condensing
The condenser condenses the steam from the exhaust of the turbine into liquid to allow it to be pumped. If the condenser can be made cooler, the pressure of the exhaust steam is reduced and efficiency of the cycle increases.

The surface condenser is a shell and tube heat exchanger in which cooling water is circulated through the tubes. The exhaust steam from the low-pressure turbine enters the shell, where it is cooled and converted to condensate (water) by flowing over the tubes as shown in the adjacent diagram. Such condensers use steam ejectors or rotary motor-driven exhausts for continuous removal of air and gases from the steam side to maintain vacuum.

For best efficiency, the temperature in the condenser must be kept as low as practical in order to achieve the lowest possible pressure in the condensing steam. Since the condenser temperature can almost always be kept significantly below 100 °C where the vapor pressure of water is much less than atmospheric pressure, the condenser generally works under vacuum. Thus leaks of non-condensible air into the closed loop must be prevented.

Typically the cooling water causes the steam to condense at a temperature of about 25 C and that creates an absolute pressure in the condenser of about 2 - 7 kPa, i.e. a vacuum of about -95 kPa relative to atmospheric pressure. The large decrease in volume that occurs when water vapor condenses to liquid creates the vacuum that generally increases the efficiency of the turbines.

The limiting factor is the temperature of the cooling water and that, in turn, is limited by the prevailing average climatic conditions at the power station's location (it may be possible to lower the temperature beyond the turbine limits during winter, causing excessive condensation in the turbine). Plants operating in hot climates may have to reduce output if their source of condenser cooling water becomes warmer; unfortunately this usually coincides with periods of high electrical demand for air conditioning.

The condenser generally uses either circulating cooling water from a cooling tower to reject waste heat to the atmosphere, or once-through cooling (OTC) water from a river, lake or ocean. In the United States, about two-thirds of power plants use OTC systems, which often have significant adverse environmental impacts. The impacts include thermal pollution and killing large numbers of fish and other aquatic species at cooling water intakes.

The heat absorbed by the circulating cooling water in the condenser tubes must also be removed to maintain the ability of the water to cool as it circulates. This is done by pumping the warm water from the condenser through either natural draft, forced draft or induced draft cooling towers (as seen in the adjacent image) that reduce the temperature of the water by evaporation, by about 11 to 17 C—expelling waste heat to the atmosphere. The circulation flow rate of the cooling water in a 500 MW unit is about 14.2 m3/s (500 ft3/s or 225,000 US gal/min) at full load.

The condenser tubes are typically made stainless steel or other alloys to resist corrosion from either side. Nevertheless, they may become internally fouled during operation by bacteria or algae in the cooling water or by mineral scaling, all of which inhibit heat transfer and reduce thermodynamic efficiency. Many plants include an automatic cleaning system that circulates sponge rubber balls through the tubes to scrub them clean without the need to take the system off-line.

The cooling water used to condense the steam in the condenser returns to its source without having been changed other than having been warmed. If the water returns to a local water body (rather than a circulating cooling tower), it is often tempered with cool 'raw' water to prevent thermal shock when discharged into that body of water.

Another form of condensing system is the air-cooled condenser. The process is similar to that of a radiator and fan. Exhaust heat from the low-pressure section of a steam turbine runs through the condensing tubes, the tubes are usually finned and ambient air is pushed through the fins with the help of a large fan. The steam condenses to water to be reused in the water-steam cycle. Air-cooled condensers typically operate at a higher temperature than water-cooled versions. While saving water, the efficiency of the cycle is reduced (resulting in more carbon dioxide per megawatt-hour of electricity).

From the bottom of the condenser, powerful condensate pumps recycle the condensed steam (water) back to the water/steam cycle.

Reheater
Power station furnaces may have a reheater section containing tubes heated by hot flue gases outside the tubes. Exhaust steam from the high-pressure turbine is passed through these heated tubes to collect more energy before driving the intermediate and then low-pressure turbines.

Air path
External fans are provided to give sufficient air for combustion. The Primary air fan takes air from the atmosphere and, first warms the air in the air preheater for better economy. Primary air then passes through the coal pulverizers, and carries the coal dust to the burners for injection into the furnace. The Secondary air fan takes air from the atmosphere and, first warms the air in the air preheater for better economy. Secondary air is mixed with the coal/primary air flow in the burners.

The induced draft fan assists the FD fan by drawing out combustible gases from the furnace, maintaining slightly below atmospheric pressure in the furnace to avoid leakage of combustion products from the boiler casing.

Steam turbine generator
A steam turbine generator consists of a series of steam turbines interconnected to each other and a generator on a common shaft.

Steam turbine
There is usually a high-pressure turbine at one end, followed by an intermediate-pressure turbine, and finally one, two, or three low-pressure turbines, and the shaft that connects to the generator. As steam moves through the system and loses pressure and thermal energy, it expands in volume, requiring increasing diameter and longer blades at each succeeding stage to extract the remaining energy. The entire rotating mass may be over 200 metric tons and 100 ft long. It is so heavy that it must be kept turning slowly even when shut down (at 3 rpm) so that the shaft will not bow even slightly and become unbalanced. This is so important that it is one of only six functions of blackout emergency power batteries on site. (The other five being emergency lighting, communication, station alarms, generator hydrogen seal system, and turbogenerator lube oil.)

For a typical late 20th-century power station, superheated steam from the boiler is delivered through 14 - 16 in piping at 2400 psi and 1000 F to the high-pressure turbine, where it falls in pressure to 600 psi and to 600 F in temperature through the stage. It exits via 24 - 26 in cold reheat lines and passes back into the boiler, where the steam is reheated in special reheat pendant tubes back to 1000 F. The hot reheat steam is conducted to the intermediate-pressure turbine, where it falls in both temperature and pressure and exits directly to the long-bladed low-pressure turbines and finally exits to the condenser.

Turbo generator
The generator, typically about 30 ft long and 12 ft in diameter, contains a stationary stator and a spinning rotor, each containing miles of heavy copper conductor. There is generally no permanent magnet, thus preventing black starts. In operation it generates up to 21,000 amperes at 24,000 volts AC (504 MWe) as it spins at either 3,000 or 3,600 rpm, synchronized to the power grid. The rotor spins in a sealed chamber cooled with hydrogen gas, selected because it has the highest known heat transfer coefficient of any gas and for its low viscosity, which reduces windage losses. This system requires special handling during startup, with air in the chamber first displaced by carbon dioxide before filling with hydrogen. This ensures that a highly explosive hydrogen–oxygen environment is not created.

The power grid frequency is 60 Hz across North America and 50 Hz in Europe, Oceania, Asia (Korea and parts of Japan are notable exceptions), and parts of Africa. The desired frequency affects the design of large turbines, since they are highly optimized for one particular speed.

The electricity flows to a distribution yard where transformers increase the voltage for transmission to its destination.

The steam turbine-driven generators have auxiliary systems enabling them to work satisfactorily and safely. The steam turbine generator, being rotating equipment, generally has a heavy, large-diameter shaft. The shaft therefore requires not only supports but also has to be kept in position while running. To minimize the frictional resistance to the rotation, the shaft has a number of bearings. The bearing shells, in which the shaft rotates, are lined with a low-friction material like Babbitt metal. Oil lubrication is provided to further reduce the friction between shaft and bearing surface and to limit the heat generated.

Stack gas path and cleanup
As the combustion flue gas exits the boiler it is routed through a rotating flat basket of metal mesh which picks up heat and returns it to incoming fresh air as the basket rotates. This is called the air preheater. The gas exiting the boiler is laden with fly ash, which are tiny spherical ash particles. The flue gas contains nitrogen along with combustion products carbon dioxide, sulfur dioxide, and nitrogen oxides. The fly ash is removed by fabric bag filters in baghouses or electrostatic precipitators. Once removed, the fly ash byproduct can sometimes be used in the manufacturing of concrete. This cleaning up of flue gases, however, only occurs in plants that are fitted with the appropriate technology. Still, the majority of coal-fired power stations in the world do not have these facilities. Legislation in Europe has been efficient to reduce flue gas pollution. Japan has been using flue gas cleaning technology for over 30 years and the US has been doing the same for over 25 years. China is now beginning to grapple with the pollution caused by coal-fired power stations.

Where required by law, the sulfur and nitrogen oxide pollutants are removed by stack gas scrubbers which use a pulverized limestone or other alkaline wet slurry to remove those pollutants from the exit stack gas. Other devices use catalysts to remove nitrous oxide compounds from the flue-gas stream. The gas travelling up the flue-gas stack may by this time have dropped to about 50 C. A typical flue-gas stack may be 150 - 180 m tall to disperse the remaining flue gas components in the atmosphere. The tallest flue-gas stack in the world is 419.7 m tall at the Ekibastuz GRES-2 Power Station in Kazakhstan.

In the United States and a number of other countries, atmospheric dispersion modeling studies are required to determine the flue-gas stack height needed to comply with the local air pollution regulations. The United States also requires the height of a flue-gas stack to comply with what is known as the "good engineering practice" (GEP) stack height. In the case of existing flue gas stacks that exceed the GEP stack height, any air pollution dispersion modeling studies for such stacks must use the GEP stack height rather than the actual stack height.

Boiler make-up water treatment plant and storage
Since there is continuous withdrawal of steam and continuous return of condensate to the boiler, losses due to blowdown and leakages have to be made up to maintain a desired water level in the boiler steam drum. For this, continuous make-up water is added to the boiler water system. Impurities in the raw water input to the plant generally consist of calcium and magnesium salts which impart hardness to the water. Hardness in the make-up water to the boiler will form deposits on the tube water surfaces which will lead to overheating and failure of the tubes. Thus, the salts have to be removed from the water, and that is done by a water demineralising treatment plant (DM). A DM plant generally consists of cation, anion, and mixed bed exchangers. Any ions in the final water from this process consist essentially of hydrogen ions and hydroxide ions, which recombine to form pure water. Very pure DM water becomes highly corrosive once it absorbs oxygen from the atmosphere because of its very high affinity for oxygen.

The capacity of the DM plant is dictated by the type and quantity of salts in the raw water input. However, some storage is essential as the DM plant may be down for maintenance. For this purpose, a storage tank is installed from which DM water is continuously withdrawn for boiler make-up. The storage tank for DM water is made from materials not affected by corrosive water, such as PVC. The piping and valves are generally of stainless steel. Sometimes, a steam blanketing arrangement or stainless steel doughnut float is provided on top of the water in the tank to avoid contact with air. DM water make-up is generally added at the steam space of the surface condenser (i.e., the vacuum side). This arrangement not only sprays the water but also DM water gets deaerated, with the dissolved gases being removed by a de-aerator through an ejector attached to the condenser.

Fuel preparation system
In coal-fired power stations, the raw feed coal from the coal storage area is first crushed into small pieces and then conveyed to the coal feed hoppers at the boilers. The coal is next pulverized into a very fine powder. The pulverizers may be ball mills, rotating drum grinders, or other types of grinders.

Some power stations burn fuel oil rather than coal. The oil must kept warm (above its pour point) in the fuel oil storage tanks to prevent the oil from congealing and becoming unpumpable. The oil is usually heated to about 100 °C before being pumped through the furnace fuel oil spray nozzles.

Boilers in some power stations use processed natural gas as their main fuel. Other power stations may use processed natural gas as auxiliary fuel in the event that their main fuel supply (coal or oil) is interrupted. In such cases, separate gas burners are provided on the boiler furnaces.

Barring gear
Barring gear (or "turning gear") is the mechanism provided to rotate the turbine generator shaft at a very low speed after unit stoppages. Once the unit is "tripped" (i.e., the steam inlet valve is closed), the turbine coasts down towards standstill. When it stops completely, there is a tendency for the turbine shaft to deflect or bend if allowed to remain in one position too long. This is because the heat inside the turbine casing tends to concentrate in the top half of the casing, making the top half portion of the shaft hotter than the bottom half. The shaft therefore could warp or bend by millionths of inches.

This small shaft deflection, only detectable by eccentricity meters, would be enough to cause damaging vibrations to the entire steam turbine generator unit when it is restarted. The shaft is therefore automatically turned at low speed (about one percent rated speed) by the barring gear until it has cooled sufficiently to permit a complete stop.

Oil system
An auxiliary oil system pump is used to supply oil at the start-up of the steam turbine generator. It supplies the hydraulic oil system required for steam turbine's main inlet steam stop valve, the governing control valves, the bearing and seal oil systems, the relevant hydraulic relays and other mechanisms.

At a preset speed of the turbine during start-ups, a pump driven by the turbine main shaft takes over the functions of the auxiliary system.

Generator cooling
While small generators may be cooled by air drawn through filters at the inlet, larger units generally require special cooling arrangements. Hydrogen gas cooling, in an oil-sealed casing, is used because it has the highest known heat transfer coefficient of any gas and for its low viscosity which reduces windage losses. This system requires special handling during start-up, with air in the generator enclosure first displaced by carbon dioxide before filling with hydrogen. This ensures that the highly flammable hydrogen does not mix with oxygen in the air.

The hydrogen pressure inside the casing is maintained slightly higher than atmospheric pressure to avoid outside air ingress, and up to about two atmospheres pressure to improve heat transfer capacity. The hydrogen must be sealed against outward leakage where the shaft emerges from the casing. Mechanical seals around the shaft are installed with a very small annular gap to avoid rubbing between the shaft and the seals on smaller turbines, with labyrinth type seals on larger machines.. Seal oil is used to prevent the hydrogen gas leakage to atmosphere.

The generator also uses water cooling. Since the generator coils are at a potential of about 22 kV, an insulating barrier such as Teflon is used to interconnect the water line and the generator high-voltage windings. Demineralized water of low conductivity is used.

Generator high-voltage system
The generator voltage for modern utility-connected generators ranges from 11 kV in smaller units to 30 kV in larger units. The generator high-voltage leads are normally large aluminium channels because of their high current as compared to the cables used in smaller machines. They are enclosed in well-grounded aluminium bus ducts and are supported on suitable insulators. The generator high-voltage leads are connected to step-up transformers for connecting to a high-voltage electrical substation (usually in the range of 115 kV to 765 kV) for further transmission by the local power grid.

The necessary protection and metering devices are included for the high-voltage leads. Thus, the steam turbine generator and the transformer form one unit. Smaller units may share a common generator step-up transformer with individual circuit breakers to connect the generators to a common bus.

Monitoring and alarm system
Most of the power station operational controls are automatic. However, at times, manual intervention may be required. Thus, the plant is provided with monitors and alarm systems that alert the plant operators when certain operating parameters are seriously deviating from their normal range.

Battery-supplied emergency lighting and communication
A central battery system consisting of lead–acid cell units is provided to supply emergency electric power, when needed, to essential items such as the power station's control systems, communication systems, generator hydrogen seal system, turbine lube oil pumps, and emergency lighting. This is essential for a safe, damage-free shutdown of the units in an emergency situation.

Circulating water system
To dissipate the thermal load of main turbine exhaust steam, condensate from gland steam condenser, and condensate from Low Pressure Heater by providing a continuous supply of cooling water to the main condenser thereby leading to condensation.

The consumption of cooling water by inland power stations is estimated to reduce power availability for the majority of thermal power stations by 2040–2069.

title: Thermal power station