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Canadian diamonds
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This article is an orphan, as no other articles link to it. Please introduce links to this page from related articles; try the Find link tool for suggestions. (January 2014)
Canadian diamonds are diamonds which have been mined in any one of the major Provinces and territories of Canada. Diamond-rich areas weren't discovered in Canada until the early 1990s.[1] Before that time, diamond mining in Canada had been essentially non-existent. However, within 10 years of their discovery, major diamond mines were unearthed and active mining began. Canada is currently the 3rd largest diamond producing country in the world.[2]
Contents
[hide]
1 History
2 Current Mines
2.1 Gahcho Kue Diamond Mine
2.2 Diavik Mine
2.3 Ekati Mine
2.4 Renard Mine
2.5 Snap Lake Mine
2.6 Victor Mine
2.7 Jericho Mine
3 Ethical Mining
4 References
5 External links
History[edit]
During the 19th century, approximately 200 small diamonds had been found across the United States, mostly in Brown and Morgan counties in Indiana. In January 1906, George F. Kunz speculated that these diamonds were glacial erratics that had been transported from an unknown site in Canada.[3]
Chuck Fipke and Stewart Blusson are credited with the discovery of the first diamond mines found in Canada in the mid 1990s.[4] The first diamond rich area they discovered was in Point Lake, but it was quickly determined to be an uneconomical piece of land. Its find though, resulted in the largest diamond staking rushes in the history of mining. This massive search resulted in the discovery of the Ekati Diamond Mine which is home to 156 kimberlite pipes. Fipke and Blusson still share a 20% ownership of the mine, and since its discovery and start of operation in 1998, Ekati has produced over 40 million carats of diamonds. The discovery and later success of this diamond mine caught the attention of other major mining operations, and more massive mines were opened and fully operational within 10 years.
Current Mines[edit]
Gahcho Kue Diamond Mine[edit]
Located approximately 53 miles southeast of the Snap Lake Diamond Mine, the Gahcho Kue Diamond Mine Project is one of the richest diamond mines in Canada with an expected lifespan of 11 years. It is estimated that 54,000,000 carats will be recovered during the mine's lifetime. The mine is a joint venture between Mountain Province Diamonds, who owns 49% and De Beers with the remaining 51%. The first sales of mined diamonds were completed in January 2017. In February 2017, a 68-carat gem quality diamond was mined, the largest in the mines short history.
Diavik Mine[edit]
Located approximately 190 miles north of Yellowknife, the Diavik Diamond Mine is one of the largest open pit diamond mines in the world (according to production) and currently produces around 8 million carats annually. The mine is currently in a transitional shift from open pit to underground mining, and the life span of the mine is expected to be 16 to 22 years from its opening in 2003.[5]
Canada’s second diamond mine, Diavik, began production in early 2003. It is an unincorporated joint venture between Diavik Diamond Mines Inc. (DDMI), which owns 60%, and Dominion Diamond Mines (formerly Harry Winston), which owns 40%. DDMI, the manager of the mine, is a wholly owned subsidiary of Rio Tinto plc, while Dominion Diamond Mines is a wholly owned subsidiary of The Washington Companies in Montana. The two joint-venture participants retain the right to market, independently, their respective share of the diamonds produced from Diavik.
Ekati Mine[edit]
The Ekati Diamond Mine is Canada’s first underground diamond operation, and is owned by Dominion Diamond Mines. To date, Ekati has produced nearly 40 million carats of uncut diamond stones out of 6 open pit mines.
Renard Mine[edit]
The Renard diamond mine is Quebec’s first diamond mine. The mine is expected to produce an average of 1.6 million carats per year over an initial 14-year mine life.
Snap Lake Mine[edit]
The Snap Lake Diamond Mine is located northeast of Yellowknife as well, not far from Diavik. Snap lake is owned by De Beers and was their first mine outside of Africa. Snap Lake is also unique in the fact that it is Canada’s first completely underground mine. De Beers spent nearly $900 million with local contractors and suppliers building the mine. Snap Lake is expected to produce 1.4 million carats annually and have an approximate life span of 20 years from its opening in 2008.
Victor Mine[edit]
The Victor Diamond Mine is the second mine constructed and operated by De Beers in Canada, and the first diamond mine located in Ontario. Victor is an open pit mine and is currently producing 600,000 carats per year of rough diamond stones.
Jericho Mine[edit]
The Jericho Diamond Mine is the only diamond mine located in Canada’s Nunavut territory, and had its initial operational period run from 2006 to 2008. During that time 780,000 carats were produced from the mine. In 2010, the mine was purchased by Shear Diamonds. They began processing diamonds from the existing recovery pile in 2012, but suspended operations later in that year.
Ethical Mining[edit]
A great deal of emphasis is placed on the Canadian diamond industry as a welcome alternative to the blood or conflict diamonds mined in Africa. Canada was one of the main supporters of the Kimberly process, a certification initiative created in 2000 to help deter the trade of conflict diamonds. All diamonds mined and cut in the Northwest Territories of Canada are laser inscribed with a unique identification number so that retailers can assure they are conflict-free stones. Taking another oppositional cue from Africa and the disastrous impacts their mining programs had on the surrounding ecosystems, all Canadian diamond mines are overseen by the Canada Mining Regulations for the Northwest Territories. This program ensures the preservation of surrounding land and aquatic habitats.
References[edit]
Jump up ^ "Canadian Diamond Discovery". Earth Explorer. Retrieved 25 February 2013.
Jump up ^ "Northwest Territories Profile". Canadian Government. Canadian Government. Retrieved 25 February 2013.
Jump up ^ "Canada May Have Gems". New York Daily Tribune. 65 (21604): 16. Jan 9, 1906. Retrieved 16 March 2018.
Jump up ^ "How Chuck Fipke Discovered Diamonds in the Canadian Arctic". Wired. Retrieved 25 February 2013.
Jump up ^ "Diamonds". Natural Resources Canada.
External links[edit]
Diamond Mines in Canada
Retrieved from "https://en.wikipedia.org/w/index.php?title=Canadian_diamonds&oldid=837665052"
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Magician: The Astonishing Life and Work of Orson Welles
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This article is about the 2014 documentary film directed by Chuck Workman. For other uses, see The Magician (disambiguation).
Magician:
The Astonishing Life and Work of Orson Welles
Theatrical release poster
Directed by
Chuck Workman
Produced by
Charles S. Cohen
Cinematography
John Sharaf
Tom Hurwitz
Michael Lisnet
Edited by
Chuck Workman
Production
companies
Cohen Welles Project
Calliope Films
Wheelhouse Creative
Distributed by
Cohen Media Group
Release date
December 10, 2014 (2014-12-10)
Running time
95 minutes
Country
United States
Language
English
Magician: The Astonishing Work and Life of Orson Welles is a 2014 American documentary film by Chuck Workman. Produced on the eve of the centenary of Orson Welles's birth, the film is a chronological review of his personal life and achievements in theatre, radio and film. It includes excerpts of nearly all of Welles's films, archival footage and audio, and interviews with colleagues, biographers, critics, friends and contemporary directors who credit his influence. First presented at numerous film festivals,[1] the film was released theatrically on December 10, 2014.[2]
Contents
[hide]
1 Synopsis
2 Production
3 Reception
4 References
5 External links
Synopsis[edit]
This section needs expansion. You can help by adding to it. (September 2015)
Production[edit]
This section needs expansion. You can help by adding to it. (September 2015)
Reception[edit]
This section needs expansion. You can help by adding to it. (September 2015)
The Observer called the film "an excellent primer on the maestro’s career".[3]
References[edit]
Jump up ^ Harvey, Dennis (October 20, 2014). "Film Review: Magician: The Astonishing Life and Work of Orson Welles". Variety. Retrieved 2015-09-07.
Jump up ^ "Magician: The Astonishing Life and Work of Orson Welles". Cohen Media Group. Retrieved 2015-09-07.
Jump up ^ Kermode, Mark (July 5, 2015). "Magician: The Astonishing Life and Work of Orson Welles review – a heady ride". The Observer. Retrieved 2015-09-07.
External links[edit]
Official site
Magician: The Astonishing Work and Life of Orson Welles at AllMovie
Magician: The Astonishing Work and Life of Orson Welles on IMDb
Magician: The Astonishing Work and Life of Orson Welles at Metacritic
Magician: The Astonishing Life and Work of Orson Welles at Rotten Tomatoes
[show]
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Orson Welles
Filmography
Radio credits
Theatre credits
Discography
Bibliography
Awards and nominations
Feature films
Citizen Kane (1941)
The Magnificent Ambersons (1942)
The Stranger (1946)
The Lady from Shanghai (1947)
Macbeth (1948)
Othello (1951)
Mr. Arkadin (1955)
Touch of Evil (1958)
The Trial (1962)
Chimes at Midnight (1965)
The Immortal Story (1968)
F for Fake (1974)
Filming Othello (1979)
Shorts
Twelfth Night (1933)
The Hearts of Age (1934)
The Green Goddess (lost film) (1939)
Citizen Kane trailer (1940)
Around the World (lost film) (1946)
The Miracle of St. Anne (lost film) (1950)
Magic Trick (1953)
The Dominici Affair (1955)
Portrait of Gina (1958)
An Evening with Orson Welles (1970)
Orson's Bag (1968–69)
incorporating Vienna (1968)
The Merchant of Venice (1969)
One Man Band, aka London (1968–71)
Moby Dick (1971)
Orson Welles' Magic Show (1976–85)
The Spirit of Charles Lindbergh (1984)
Unfinished films
Too Much Johnson (1938)
It's All True (1942)
Don Quixote (1957–69)
The Heroine (lost film) (1967)
The Deep (1967–70)
The Other Side of the Wind (1970–76)
Filming 'The Trial' (1981)
The Dreamers (1980–82)
Television
Orson Welles' Sketch Book (1955)
Around the World with Orson Welles (1955)
Orson Welles and People (lost) (1956)
The Fountain of Youth (1958)
In the Land of Don Quixote (1964)
The Orson Welles Show (1979)
Theatre
Marching Song (1932)
Bright Lucifer
Voodoo Macbeth (1936)
Horse Eats Hat (1936)
Caesar (1937–38)
Too Much Johnson (1938)
Native Son (1941)
The Mercury Wonder Show (1943)
Around the World (musical) (1946)
Othello (1951)
The Lady in the Ice (ballet) (1953)
Moby Dick—Rehearsed (1955)
Rhinoceros (1960)
Radio
Les Misérables (1937)
The Shadow (1937–38)
The Mercury Theatre on the Air (including "Dracula" and "The War of the Worlds") (1938)
The Campbell Playhouse (1938–40)
Orson Welles Show (1941–42)
Ceiling Unlimited (1942–43)
Hello Americans (1942–43)
The Orson Welles Almanac (1944)
This Is My Best (1945)
Orson Welles Commentaries (1945–46)
The Mercury Summer Theatre on the Air (1946)
The Adventures of Harry Lime (1951–52)
The Black Museum (1951–52)
Spoken-word recordings
The Happy Prince (1946)
The Airborne Symphony (1966)
The Begatting of the President (1970)
Books
This is Orson Welles (1992)
Les Bravades (1996)
Related
Mercury Theatre
Paola Mori (third wife)
Beatrice Welles (daughter)
Oja Kodar
Frozen Peas
Orson Welles Paul Masson adverts
It's All True: Based on an Unfinished Film by Orson Welles (1993 documentary)
Magician: The Astonishing Life and Work of Orson Welles (2014 documentary)
Orson Welles (crater)
This article about a biographical documentary film is a stub. You can help Wikipedia by expanding it.
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Retrieved from "https://en.wikipedia.org/w/index.php?title=Magician:_The_Astonishing_Life_and_Work_of_Orson_Welles&oldid=814721597"
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2010s documentary films
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Films about Orson Welles
Documentary films about film directors and producers
Films directed by Chuck Workman
Films about magic and magicians
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This page was last edited on 10 December 2017, at 14:42.
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Ulta Beauty
From Wikipedia, the free encyclopedia
Jump to: navigation, search
This article may rely excessively on sources too closely associated with the subject, potentially preventing the article from being verifiable and neutral. Please help improve it by replacing them with more appropriate citations to reliable, independent, third-party sources. (October 2015) (Learn how and when to remove this template message)
Ulta Salon, Cosmetics & Fragrance, Inc.
Trading name
Ulta Beauty
Type
Public
Traded as
NASDAQ: ULTA
NASDAQ-100 Component
S&P 500 Component
Founded
1990 (1990)
Headquarters
Bolingbrook, Illinois
Number of locations
974 (January 2017)[1]
Key people
Mary Dillon, CEO
Revenue
US$ 4.855 billion (2016)
Net income
US$ 409.8 million (2016)
Total assets
US$ 2.552 billion (2016)
Number of employees
21,700[2]
Website
www.ulta.com
Ulta Beauty, Inc., (formerly known as Ulta Salon, Cosmetics & Fragrance, Inc. until January 2017), is a chain of beauty stores in the United States, headquartered in Bolingbrook, Illinois.[3] Ulta Beauty carries cosmetics and skincare brands, men's and women's fragrances, and haircare products. Each store is also equipped with a salon.
Contents
[hide]
1 History
2 Operations
3 Charitable giving
4 References
5 External links
History[edit]
Ulta Salon, Cosmetics and Fragrance was founded by Richard E. George, the former President of Osco Drug, Inc. Following his tenure, Terry J. Hanson, another Osco veteran, became the CEO. In September 1996, Hanson hired Charles "Rick" Weber, another Osco veteran, to be Chief Financial Officer. In December 1999, Lyn Kirby, formerly of Sears Circle of Beauty, became the President and Chief Executive Officer and Weber became Senior Executive Vice President, Chief Operating Officer and Chief Financial Officer. The two ran the business together until Weber left in September 2006 when he was selected by Tom Stemberg, founder of Staples, to become Chairman and Chief Executive officer of Rec Room Furniture and Games, Inc.[2] On October 25, 2007, the company became publicly traded on the NASDAQ. In 2008, the company opened a second distribution center in Phoenix, Arizona. On April 26, 2010, Ulta announced that Mr. Carl "Chuck" Rubin would be appointed as Chief Operating Officer, President, and as a member of the Board of Directors, effective May 10, 2010. According to public filings, Chuck Rubin earned over $11.1MM in 2010, making him one of the 20 highest paid CEOs in Chicago.[4]
Ulta Beauty, Ann Arbor, Michigan
On June 24, 2013, it was announced that Mary Dillon would be appointed as Chief Executive Officer and a member of the Board of Directors, effective July 1, 2013. Mary Dillon previously held positions as the former chief of U.S. Cellular and senior executive at McDonald's and PepsiCo.[5]
Operations[edit]
In 2013, Ulta opened 125 stores in the United States, bringing their total number of locations to 675 stores. They also announced plans to open 100 more locations by the end of 2014.[6] As of January 28, 2017, Ulta operates 974 stores in 48 states and the District of Columbia.[1] A majority of Ulta Beauty stores are located in the East Coast region, however on the West Coast, California also has a large presence of company-owned stores.[7] Ulta said it aims to have 1,000 stores located in the United States sometime during 2017.[8]
Ulta Beauty offers both high-end and drugstore cosmetics, skincare, and fragrances,[9] in addition to its own brand of makeup, bath and body products, skincare, haircare, nail polish, and fragrances. In May 2017, MAC Cosmetics became available for purchase online,[10] with products scheduled to be in stores beginning in June 2017.[11]
Ulta has a salon located in every store nationwide. The store format includes a 950 square feet salon area with eight to ten stations. The salon has a concierge desk, skin treatment room, and semi-private shampoo and hair color processing areas. It offers services including hair cuts and hair coloring from Redken-trained hair stylists, skin treatments and facials from Dermalogica trained skin therapists, and manicures from OPI trained professionals.[12] They additionally include the Benefit Brow Bar, which includes services such as: brow arching, brow tinting, facial waxing, and eyelash application.[13]
Ulta Beauty sales were $713.8 million for the first quarter ending in May 2014.[14] At the end of the second quarter ending in August 2014, Ulta Beauty reported that total sales increased by 22.2 percent and comparable store sales Increased 9.6 percent.[15] Wall Street expected the company's total sales to reach $3.19 billion for the fiscal year ending in February 2015, which would be almost three times the amount of Ulta Beauty's sales levels in 2009.[16]
Charitable giving[edit]
Starting in 2008, Ulta Beauty's focus in charity giving was The Breast Cancer Research Foundation.[17] Ulta Beauty also hosts programs such as their annual Donate with a Kiss campaign, which raises funds for The Breast Cancer Research Foundation throughout the month of October, Ulta Beauty's Annual Charity Gold Outing, as well as Ulta Beauty's Annual Cut-A-Thon, where customers donate ten dollars to the cause in exchange for a haircut. In 2012, ULTA Beauty raised over 2 million dollars for The Breast Cancer Research Foundation.[18] In 2014, Ulta Beauty partnered with Ellen DeGeneres during Breast Cancer Awareness Month in October and donated $2 million for The Breast Cancer Research Foundation.[19]
References[edit]
^ Jump up to: a b "Company Overview". Ulta.
^ Jump up to: a b "About Ulta Beauty | Ulta Beauty Corporate". www.ulta.com. Retrieved 2017-10-31.
Jump up ^ "About Us". Ulta.
Jump up ^ "Chicago's $10 million CEOs". Chicago Tribune. [date missing]
Jump up ^ "Ulta Beauty Names Mary Dillion Chief Executive Officer". Yahoo! Finance.
Jump up ^ "Beauty Emporiums Including Sephora and Ulta Are Riding a Wave of Popularity". New York Times. April 30, 2014.
Jump up ^ "Our Locations". Ulta.
Jump up ^ "Beauty Retailer Ulta aims for 1000 stores by 2017". Reuters.
Jump up ^ http://www.theagencysd.com/2012/11/battle-of-the-brands-sephora-vs-ulta/
Jump up ^ Low, Elaine (3 May 2017). "Ulta Beauty Shares Break Out As Estee Lauder Pops On Earnings". Investor's Business Daily. Retrieved 8 May 2017.
Jump up ^ Shapouri, Beth. "MAC Cosmetics Is Coming to Ulta, and Now Our Wallets Are in Trouble". Glamour. Retrieved 28 March 2017.
Jump up ^ "Services Menu". Ulta.
Jump up ^ "Brow Bar". Ulta.
Jump up ^ "Ulta beats 1st-quarter estimate". Chicago Tribune.
Jump up ^ "News Release: Ulta Beauty Announces Second Quarter 2014 Results". Ulta.
Jump up ^ "ULTA's Growth".
Jump up ^ "Ulta Beauty Gives Back: Charitable Giving at Ulta Beauty". Ulta.
Jump up ^ "PR Newswire: ULTA Beauty Cut-A-Thon In Support Of The Breast Cancer Research Foundation".
Jump up ^ "What retail CEO made an appearance on The Ellen DeGeneres Show? |Chain Store Age". Chain Store Age. 2015-11-01. Retrieved 2017-10-31.
External links[edit]
Wikimedia Commons has media related to Ulta Beauty stores.
Official website
Business data for Ulta Beauty: Google Finance
Yahoo! Finance
Reuters
SEC filings
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DC-to-DC converter
From Wikipedia, the free encyclopedia
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A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low (small batteries) to very high (high-voltage power transmission).
Contents
[hide]
1 History
2 Uses
3 Electronic conversion
3.1 Magnetic
3.2 Capacitive
4 Electromechanical conversion
5 Electrochemical conversion
6 Chaotic behavior
7 Terminology
8 See also
9 References
10 External links
History[edit]
See also: Antique radio § Car radios
Before the development of power semiconductors and allied technologies, one way to convert the voltage of a DC supply to a higher voltage, for low-power applications, was to convert it to AC by using a vibrator, followed by a step-up transformer and rectifier.[1][2] For higher power an electric motor was used to drive a generator of the desired voltage (sometimes combined into a single "dynamotor" unit, a motor and generator combined into one unit, with one winding driving the motor and the other generating the output voltage). These were relatively inefficient and expensive procedures used only when there was no alternative, as to power a car radio (which then used thermionic valves/tubes requiring much higher voltages than available from a 6 or 12 V car battery).[1] The introduction of power semiconductors and integrated circuits made it economically viable to use techniques as described below, for example to convert the DC power supply to high-frequency AC, use a transformer—small, light, and cheap due to the high frequency—to change the voltage, and rectify back to DC.[3] Although by 1976 transistor car radio receivers did not require high voltages, some amateur radio operators continued to use vibrator supplies and dynamotors for mobile transceivers requiring high voltages, although transistorised power supplies were available.[4]
While it was possible to derive a lower voltage from a higher with a linear electronic circuit, or even a resistor, these methods dissipated the excess as heat; energy-efficient conversion only became possible with solid-state switch-mode circuits.
Uses[edit]
DC to DC converters are used in portable electronic devices such as cellular phones and laptop computers, which are supplied with power from batteries primarily. Such electronic devices often contain several sub-circuits, each with its own voltage level requirement different from that supplied by the battery or an external supply (sometimes higher or lower than the supply voltage). Additionally, the battery voltage declines as its stored energy is drained. Switched DC to DC converters offer a method to increase voltage from a partially lowered battery voltage thereby saving space instead of using multiple batteries to accomplish the same thing.
Most DC to DC converter circuits also regulate the output voltage. Some exceptions include high-efficiency LED power sources, which are a kind of DC to DC converter that regulates the current through the LEDs, and simple charge pumps which double or triple the output voltage.
DC to DC converters developed to maximize the energy harvest for photovoltaic systems and for wind turbines are called power optimizers.
Transformers used for voltage conversion at mains frequencies of 50–60 Hz must be large and heavy for powers exceeding a few watts. This makes them expensive, and they are subject to energy losses in their windings and due to eddy currents in their cores. DC-to-DC techniques that use transformers or inductors work at much higher frequencies, requiring only much smaller, lighter, and cheaper wound components. Consequently these techniques are used even where a mains transformer could be used; for example, for domestic electronic appliances it is preferable to rectify mains voltage to DC, use switch-mode techniques to convert it to high-frequency AC at the desired voltage, then, usually, rectify to DC. The entire complex circuit is cheaper and more efficient than a simple mains transformer circuit of the same output.
Electronic conversion[edit]
Practical electronic converters use switching techniques. Switched-mode DC-to-DC converters convert one DC voltage level to another, which may be higher or lower, by storing the input energy temporarily and then releasing that energy to the output at a different voltage. The storage may be in either magnetic field storage components (inductors, transformers) or electric field storage components (capacitors). This conversion method can increase or decrease voltage. Switching conversion is more power efficient (often 75% to 98%) than linear voltage regulation, which dissipates unwanted power as heat. Fast semiconductor device rise and fall times are required for efficiency; however, these fast transitions combine with layout parasitic effects to make circuit design challenging.[5] The higher efficiency of a switched-mode converter reduces the heatsinking needed, and increases battery endurance of portable equipment. Efficiency has improved since the late 1980s due to the use of power FETs, which are able to switch more efficiently with lower switching losses at higher frequencies than power bipolar transistors, and use less complex drive circuitry. Another important improvement in DC-DC converters is replacing the flywheel diode by synchronous rectification[6] using a power FET, whose "on resistance" is much lower, reducing switching losses. Before the wide availability of power semiconductors, low-power DC-to-DC synchronous converters consisted of an electro-mechanical vibrator followed by a voltage step-up transformer feeding a vacuum tube or semiconductor rectifier, or synchronous rectifier contacts on the vibrator.
Most DC-to-DC converters are designed to move power in only one direction, from dedicated input to output. However, all switching regulator topologies can be made bidirectional and able to move power in either direction by replacing all diodes with independently controlled active rectification. A bidirectional converter is useful, for example, in applications requiring regenerative braking of vehicles, where power is supplied to the wheels while driving, but supplied by the wheels when braking.
Although they require few components, switching converters are electronically complex. Like all high-frequency circuits, their components must be carefully specified and physically arranged to achieve stable operation and to keep switching noise (EMI / RFI) at acceptable levels[7]. Their cost is higher than linear regulators in voltage-dropping applications, but their cost has been decreasing with advances in chip design.
DC-to-DC converters are available as integrated circuits (ICs) requiring few additional components. Converters are also available as complete hybrid circuit modules, ready for use within an electronic assembly.
Linear regulators which are used to output a stable DC independent of input voltage and output load from a higher but less stable input by dissipating excess volt-amperes as heat, could be described literally as DC-to-DC converters, but this is not usual usage. (The same could be said of a simple voltage dropper resistor, whether or not stabilised by a following voltage regulator or Zener diode.)
There are also simple capacitive voltage doubler and Dickson multiplier circuits using diodes and capacitors to multiply a DC voltage by an integer value, typically delivering only a small current.
Magnetic[edit]
In these DC-to-DC converters, energy is periodically stored within and released from a magnetic field in an inductor or a transformer, typically within a frequency range of 300 kHz to 10 MHz. By adjusting the duty cycle of the charging voltage (that is, the ratio of the on/off times), the amount of power transferred to a load can be more easily controlled, though this control can also be applied to the input current, the output current, or to maintain constant power. Transformer-based converters may provide isolation between input and output. In general, the term DC-to-DC converter refers to one of these switching converters. These circuits are the heart of a switched-mode power supply. Many topologies exist. This table shows the most common ones.
Forward (energy transfers through the magnetic field)
Flyback (energy is stored in the magnetic field)
No transformer (non-isolated)
Step-down (buck) - The output voltage is lower than the input voltage, and of the same polarity.
Non-inverting: The output voltage is the same polarity as the input.
Step-up (boost) - The output voltage is higher than the input voltage.
SEPIC - The output voltage can be lower or higher than the input.
Inverting: the output voltage is of the opposite polarity as the input.
Inverting (buck-boost).
Ćuk - Output current is continuous.
True buck-boost - The output voltage is the same polarity as the input and can be lower or higher.
Split-pi (boost-buck) - Allows bidirectional voltage conversion with the output voltage the same polarity as the input and can be lower or higher.
With transformer (isolatable)
Forward - 1 or 2 transistor drive.
Push-pull (half bridge) - 2 transistors drive.
Full bridge - 4 transistor drive.
Flyback - 1 transistor drive.
In addition, each topology may be:
Hard switched
Transistors switch quickly while exposed to both full voltage and full current
Resonant
An LC circuit shapes the voltage across the transistor and current through it so that the transistor switches when either the voltage or the current is zero
Magnetic DC-to-DC converters may be operated in two modes, according to the current in its main magnetic component (inductor or transformer):
Continuous
The current fluctuates but never goes down to zero
Discontinuous
The current fluctuates during the cycle, going down to zero at or before the end of each cycle
A converter may be designed to operate in continuous mode at high power, and in discontinuous mode at low power.
The half bridge and flyback topologies are similar in that energy stored in the magnetic core needs to be dissipated so that the core does not saturate. Power transmission in a flyback circuit is limited by the amount of energy that can be stored in the core, while forward circuits are usually limited by the I/V characteristics of the switches.
Although MOSFET switches can tolerate simultaneous full current and voltage (although thermal stress and electromigration can shorten the MTBF), bipolar switches generally can't so require the use of a snubber (or two).
High-current systems often use multiphase converters, also called interleaved converters.[8][9][10] Multiphase regulators can have better ripple and better response times than single-phase regulators.[11]
Many laptop and desktop motherboards include interleaved buck regulators, sometimes as a voltage regulator module.[12]
Capacitive[edit]
Main article: Charge pump
Switched capacitor converters rely on alternately connecting capacitors to the input and output in differing topologies. For example, a switched-capacitor reducing converter might charge two capacitors in series and then discharge them in parallel. This would produce the same output power (less that lost to efficiency of under 100%) at, ideally, half the input voltage and twice the current. Because they operate on discrete quantities of charge, these are also sometimes referred to as charge pump converters. They are typically used in applications requiring relatively small currents, as at higher currents the increased efficiency and smaller size of switch-mode converters makes them a better choice.[13] They are also used at extremely high voltages, as magnetics would break down at such voltages.
Electromechanical conversion[edit]
Main article: Motor-generator
A motor generator with separate motor and generator.
A motor-generator set, mainly of historical interest, consists of an electric motor and generator coupled together. A dynamotor combines both functions into a single unit with coils for both the motor and the generator functions wound around a single rotor; both coils share the same outer field coils or magnets.[4] Typically the motor coils are driven from a commutator on one end of the shaft, when the generator coils output to another commutator on the other end of the shaft. The entire rotor and shaft assembly is smaller in size than a pair of machines, and may not have any exposed drive shafts.
Motor-generators can convert between any combination of DC and AC voltage and phase standards. Large motor-generator sets were widely used to convert industrial amounts of power while smaller units were used to convert battery power (6, 12 or 24 V DC) to a high DC voltage, which was required to operate vacuum tube (thermionic valve) equipment.
For lower-power requirements at voltages higher than supplied by a vehicle battery, vibrator or "buzzer" power supplies were used. The vibrator oscillated mechanically, with contacts that switched the polarity of the battery many times per second, effectively converting DC to square wave AC, which could then be fed to a transformer of the required output voltage(s).[1] It made a characteristic buzzing noise.
Electrochemical conversion[edit]
A further means of DC to DC conversion in the kilowatts to megawatts range is presented by using redox flow batteries such as the vanadium redox battery.
Chaotic behavior[edit]
DC-to-DC converters are subject to different types of chaotic dynamics such as bifurcation,[14] crisis, and intermittency.[15][16]
Terminology[edit]
Step-down
A converter where output voltage is lower than the input voltage (such as a buck converter).
Step-up
A converter that outputs a voltage higher than the input voltage (such as a boost converter).
Continuous current mode
Current and thus the magnetic field in the inductive energy storage never reach zero.
Discontinuous current mode
Current and thus the magnetic field in the inductive energy storage may reach or cross zero.
Noise
Unwanted electrical and electromagnetic signal noise, typically switching artifacts.
RF noise
Switching converters inherently emit radio waves at the switching frequency and its harmonics. Switching converters that produce triangular switching current, such as the Split-Pi, forward converter, or Ćuk converter in continuous current mode, produce less harmonic noise than other switching converters.[17] RF noise causes electromagnetic interference (EMI). Acceptable levels depend upon requirements, e.g. proximity to RF circuitry needs more suppression than simply meeting regulations.
Input noise
The input voltage may have non-negligible noise. Additionally, if the converter loads the input with sharp load edges, the converter can emit RF noise from the supplying power lines. This should be prevented with proper filtering in the input stage of the converter.
Output noise
The output of an ideal DC-to-DC converter is a flat, constant output voltage. However, real converters produce a DC output upon which is superimposed some level of electrical noise. Switching converters produce switching noise at the switching frequency and its harmonics. Additionally, all electronic circuits have some thermal noise. Some sensitive radio-frequency and analog circuits require a power supply with so little noise that it can only be provided by a linear regulator.[citation needed] Some analog circuits which require a power supply with relatively low noise can tolerate some of the less-noisy switching converters, e.g. using continuous triangular waveforms rather than square waves.[17][not in citation given]
See also[edit]
Switched-mode power supply
References[edit]
^ Jump up to: a b c "Vibrator Power Supplies". Radioremembered.org. Retrieved 18 January 2016.
Jump up ^ Ed Brorein (2012-05-16). "Watt's Up?: What Is Old is New Again: Soft-Switching and Synchronous Rectification in Vintage Automobile Radios". Keysight Technologies: Watt's Up?. Retrieved 2016-01-19.
Jump up ^ There is at least one example of a very large (three refrigerator-sized cabinets) and complex pre-transistor switching regulator using thyratron gas-filled tubes, although they appear to be used as regulators rather than for DC-to-DC conversion as such. This was the 1958 power supply for the IBM 704 computer, using 90 kW of power.[1]
^ Jump up to: a b Radio Amateur's Handbook 1976, pub. ARRL, p331-332
Jump up ^ Andy Howard (2015-08-25). "How to Design DC-to-DC Converters". YouTube. Retrieved 2015-10-02.
Jump up ^ Stephen Sangwine (2 March 2007). Electronic Components and Technology, Third Edition. CRC Press. p. 73. ISBN 978-1-4200-0768-8.
Jump up ^ Jeff Barrow of Integrated Device Technology, Inc. (21 November 2011). "Understand and reduce DC/DC switching-converter ground noise". Eetimes.com. Retrieved 18 January 2016.
Jump up ^ Damian Giaouris et al. "Foldings and grazings of tori in current controlled interleaved boost converters". doi: 10.1002/cta.1906.
Jump up ^ Ron Crews and Kim Nielson. "Interleaving is Good for Boost Converters, Too". 2008.
Jump up ^ Keith Billings. "Advantages of Interleaving Converters". 2003.
Jump up ^ John Gallagher "Coupled Inductors Improve Multiphase Buck Efficiency". 2006.
Jump up ^ Juliana Gjanci. "On-Chip Voltage Regulation for Power Management inSystem-on-Chip" Archived 2012-11-19 at the Wayback Machine.. 2006. p. 22-23.
Jump up ^ Majumder, Ritwik; Ghosh, Arindam; Ledwich, Gerard F.; Zare, Firuz (2008). "Control of Parallel Converters for Load Sharing with Seamless Transfer between Grid Connected and Islanded Modes". eprints.qut.edu.au. Retrieved 2016-01-19.
Jump up ^ Tse, Chi K.; Bernardo, Mario Di (2002). Complex behavior in switching power converters. Proceedings of the IEEE. pp. 768–781.
Jump up ^ Iqbal, Sajid; et al. (2014). Study of bifurcation and chaos in dc-dc boost converter using discrete-time map. IEEE International Conference on Mechatronics and Control (ICMC'2014) 2014. doi:10.1109/ICMC.2014.7231874.
Jump up ^ Fossas, , Enric; Olivar, Gerard (1996). "Study of chaos in the buck converter". Circuits and Systems I: Fundamental Theory and Applications, IEEE Transactions on: 13–25.
^ Jump up to: a b Making -5V 14-bit Quiet, section of Linear Technology Application Note 84, Kevin Hoskins, 1997, pp 57-59
External links[edit]
DC DC Power Converters circuits electronics projects
DC-DC Converter Technologies for Electric/Hybrid Electric Vehicles
Power Electronics Books
Switching regulator application note for LCD Power supply
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Mid-Atlantic Ridge
From Wikipedia, the free encyclopedia
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A map of the Mid-Atlantic Ridge
The Mid-Atlantic Ridge (MAR) is a mid-ocean ridge, a divergent tectonic plate or constructive plate boundary located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic it separates the Eurasian and North American Plates, and in the South Atlantic it separates the African and South American Plates. The ridge extends from a junction with the Gakkel Ridge (Mid-Arctic Ridge) northeast of Greenland southward to the Bouvet Triple Junction in the South Atlantic. Although the Mid-Atlantic Ridge is mostly an underwater feature, portions of it have enough elevation to extend above sea level. The section of the ridge that includes Iceland is known as the Reykjanes Ridge. The ridge has an average spreading rate of about 2.5 centimetres (0.98 in) per year.[1]
Contents
[hide]
1 Discovery
2 Notable features
3 Islands
4 Geology
5 See also
6 References
7 Bibliography
8 External links
Discovery[edit]
Pangaea's separation animated
A ridge under the Atlantic Ocean was first inferred by Matthew Fontaine Maury in 1850. The existence of the ridge was discovered during the expedition of HMS Challenger in 1872.[2] A team of scientists on board, led by Charles Wyville Thomson, discovered a large rise in the middle of the Atlantic while investigating the future location for a transatlantic telegraph cable.[3] The existence of such a ridge was confirmed by sonar in 1925[4] and was found to extend around the Cape of Good Hope into the Indian Ocean by the German Meteor expedition.[5]
In the 1950s, mapping of the Earth's ocean floors by Bruce Heezen, Maurice Ewing, Marie Tharp and others revealed that the Mid-Atlantic Ridge had a strange bathymetry of valleys and ridges,[6] with its central valley being seismologically active and the epicenter of many earthquakes.[7][8] Ewing, Heezen and Tharp discovered that the ridge is part of a 40,000-km-long essentially continuous system of mid-ocean ridges on the floors of all the Earth’s oceans.[9] The discovery of this worldwide ridge system led to the theory of seafloor spreading and general acceptance of Wegener's theory of continental drift and expansion in the modified form of plate tectonics. The ridge is central to the breakup of the hypothetical supercontinent of Pangaea that began some 180 million years ago.
Notable features[edit]
In Iceland the Mid-Atlantic Ridge passes across the Þingvellir National Park, a popular destination for tourists
The Mid-Atlantic Ridge includes a deep rift valley that runs along the axis of the ridge along nearly its entire length. This rift marks the actual boundary between adjacent tectonic plates, where magma from the mantle reaches the seafloor, erupting as lava and producing new crustal material for the plates.
Near the equator, the Mid-Atlantic Ridge is divided into the North Atlantic Ridge and the South Atlantic Ridge by the Romanche Trench, a narrow submarine trench with a maximum depth of 7,758 m (25,453 ft), one of the deepest locations of the Atlantic Ocean. This trench, however, is not regarded as the boundary between the North and South American Plates, nor the Eurasian and African Plates.
Islands[edit]
The islands on or near the Mid-Atlantic Ridge, from north to south, with their respective highest peaks and location, are:
Northern Hemisphere (North Atlantic Ridge):
Jan Mayen (Beerenberg, 2277 m (at 71°06′N 08°12′W / 71.100°N 8.200°W / 71.100; -8.200), in the Arctic Ocean
Iceland (Hvannadalshnúkur at Vatnajökull, 2109.6 m (at 64°01′N 16°41′W / 64.017°N 16.683°W / 64.017; -16.683), through which the ridge runs
Azores (Ponta do Pico or Pico Alto, on Pico Island, 2351 m, (at 38°28′0″N 28°24′0″W / 38.46667°N 28.40000°W / 38.46667; -28.40000)
Saint Peter and Paul Rocks (Southwest Rock, 22.5 m, at 00°55′08″N 29°20′35″W / 0.91889°N 29.34306°W / 0.91889; -29.34306)
Southern Hemisphere (South Atlantic Ridge):
Ascension Island (The Peak, Green Mountain, 859 m, at 07°59′S 14°25′W / 7.983°S 14.417°W / -7.983; -14.417)
Saint Helena (Diana's Peak, 818 m at 15°57′S 5°41′W / 15.950°S 5.683°W / -15.950; -5.683)
Tristan da Cunha (Queen Mary's Peak, 2062 m, at 37°05′S 12°17′W / 37.083°S 12.283°W / -37.083; -12.283)
Gough Island (Edinburgh Peak, 909 m, at 40°20′S 10°00′W / 40.333°S 10.000°W / -40.333; -10.000)
Bouvet Island (Olavtoppen, 780 m, at 54°24′S 03°21′E / 54.400°S 3.350°E / -54.400; 3.350)
Geology[edit]
Basaltic rocks of the MAR collected by the Hercules ROV during the 2005 Lost City Expedition.
For a general explanation of mid-oceanic ridges, see mid-oceanic ridge and seafloor spreading
The ridge sits atop a geologic feature known as the Mid-Atlantic Rise, which is a progressive bulge that runs the length of the Atlantic Ocean, with the ridge resting on the highest point of this linear bulge. This bulge is thought to be caused by upward convective forces in the asthenosphere pushing the oceanic crust and lithosphere. This divergent boundary first formed in the Triassic period, when a series of three-armed grabens coalesced on the supercontinent Pangaea to form the ridge. Usually, only two arms of any given three-armed graben become part of a divergent plate boundary. The failed arms are called aulacogens, and the aulacogens of the Mid-Atlantic Ridge eventually became many of the large river valleys seen along the Americas and Africa (including the Mississippi River, Amazon River and Niger River). The Fundy Basin on the Atlantic coast of North America between New Brunswick and Nova Scotia in Canada is evidence of the ancestral Mid-Atlantic Ridge.[10][11]
See also[edit]
Atlantis Massif
Central Atlantic Magmatic Province
Fifteen-Twenty Fracture Zone
References[edit]
Jump up ^ USGS (5 May 1999). "Understanding plate motions". Retrieved 13 March 2011.
Jump up ^ Hsü, Kenneth J. (1992). Challenger at Sea: A Ship That Revolutionized Earth Science. Princeton University Press. p. 57. ISBN 0-691-08735-0.
Jump up ^ Redfern, R.; 2001: Origins, the Evolution of Continents, Oceans and Life, University of Oklahoma Press, ISBN 1-84188-192-9, p. 26
Jump up ^ Alexander Hellemans and Brian Bunch, 1989, Timeline of Science, Sidgwick and Jackson, London
Jump up ^ Stein, Glenn, A Victory in Peace: The German Atlantic Expedition 1925-27, June 2007
Jump up ^ Ewing, W.M.; Dorman, H.J.; Ericson, J.N.; Heezen, B.C. (1953). "Exploration of the northwest Atlantic mid-ocean canyon". Bulletin of the Geological Society of America. 64 (7): 865–868. doi:10.1130/0016-7606(1953)64[865:eotnam]2.0.co;2.
Jump up ^ Heezen, B. C.; Tharp, M. (1954). "Physiographic diagram of the western North Atlantic". Bulletin of the Geological Society of America. 65: 1261.
Jump up ^ Hill, M.N.; Laughton, A.S. (1954). "Seismic Observations in the Eastern Atlantic, 1952". Proceedings of the Royal Society of London A: Mathematical and Physical Sciences. 222 (1150): 348–356. doi:10.1098/rspa.1954.0078.
Jump up ^ Spencer, Edgar W. (1977). Introduction to the Structure of the Earth (2nd ed.). Tokyo: McGraw-Hill. ISBN 0-07-085751-2.
Jump up ^ Burke, K.; Dewey, J. F. (1973). "Plume-generated triple junctions: key indicators in applying plate tectonics to old rocks" (PDF). The Journal of Geology. 81 (4): 406–433. doi:10.1086/627882. JSTOR 30070631.
Jump up ^ Burke, K. (1976). "Development of graben associated with the initial ruptures of the Atlantic Ocean". Tectonophysics. 36 (1–3): 93–112. doi:10.1016/0040-1951(76)90009-3.
Bibliography[edit]
Evans, Rachel. "Plumbing Depths to Reach New Heights: Marie Tharp Explains Marine Geological Maps." The Library of Congress Information Bulletin. November 2002.
External links[edit]
MAR-ECO, a Census of Marine Life project on life along the Mid-Atlantic Ridge
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Retrieved from "https://en.wikipedia.org/w/index.php?title=Mid-Atlantic_Ridge&oldid=848578969"
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