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United States Secretary of State
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Not to be confused with Secretary of state (U.S. state government).
Secretary of State of the United States
Seal of the Secretary of State
Flag of the Secretary of State
Incumbent
Rex Tillerson
since February 1, 2017
United States Department of State
Style
Mr. Secretary
Member of
Cabinet, National Security Council
Reports to
The President
Seat
Washington, D.C.
Appointer
The President
with Senate advice and consent
Term length
Appointed
Constituting instrument
22 U.S.C. § 2651
Precursor
United States Secretary of Foreign Affairs
Formation
July 27, 1789; 228 years ago (1789-07-27)
First holder
John Jay (acting)
Thomas Jefferson
Succession
Fourth[1]
Deputy
John Sullivan
Salary
$205,700 annually[2] (Executive Schedule I)[3]
Website
www.state.gov
The Secretary of State is a senior official of the federal government of the United States of America, and as head of the U.S. Department of State, is principally concerned with foreign policy and is considered to be the U.S. government's equivalent of a Minister for Foreign Affairs.[4][5]
The Secretary of State is nominated by the President of the United States and, following a confirmation hearing before the Senate Committee on Foreign Relations, is confirmed by the United States Senate. The Secretary of State, along with the Secretary of the Treasury, Secretary of Defense, and Attorney General, are generally regarded as the four most important Cabinet members because of the importance of their respective departments.[6] Secretary of State is a Level I position in the Executive Schedule and thus earns the salary prescribed for that level (currently $205,700).[3]
The current Secretary of State is former ExxonMobil CEO Rex Tillerson, the 69th person to hold office since its creation in 1789.
Contents
[hide]
1 Duties and responsibilities
2 List of Secretaries of State
3 References
4 External links
Duties and responsibilities[edit]
The stated duties of the Secretary of State are as follows:[7]
"Supervises the United States Foreign Service" and "administers the Department of State"
Advises the President on matters relating to U.S. foreign policy including the appointment of diplomatic representatives to other nations and on the acceptance, recall, or dismissal of representatives from other nations
"Negotiates, interprets, or terminates treaties and agreements" and "conducts negotiations relating to U.S. foreign affairs"
"Personally participates in or directs U.S. representatives to international conferences, organizations, and agencies"
Provides information and services to U.S. citizens living or traveling abroad such as providing credentials in the form of passports
"Ensures the protection of the U.S. Government to American citizens, property, and interests in foreign countries"
"Supervises the administration of the U.S. immigration policy abroad"
Communicates issues relating the U.S. foreign policy to Congress and to U.S. citizens
"Promotes beneficial economic intercourse between the U.S. and other countries"
The original duties of the Secretary of State include some domestic duties such as:[citation needed]
Receipt, publication, distribution, and preservation of the laws of the United States
Preparation, sealing, and recording of the commissions of Presidential appointees
Preparation and authentication of copies of records and authentication of copies under the Department's seal
Custody of the Great Seal of the United States
Custody of the records of former Secretary of the Continental Congress except for those of the Treasury and War departments
Most of the domestic functions of the Department of State have been transferred to other agencies. Those that remain include storage and use of the Great Seal of the United States, performance of protocol functions for the White House, and the drafting of certain proclamations. The Secretary also negotiates with the individual States over the extradition of fugitives to foreign countries.[8] Under Federal Law,[9] the resignation of a President or of a Vice President is only valid if declared in writing, in an instrument delivered to the office of the Secretary of State. Accordingly, the resignations of President Nixon and of Vice-President Spiro Agnew, domestic issues, were formalized in instruments delivered to the Secretary of State, Henry Kissinger.
As the highest-ranking member of the cabinet, the Secretary of State is the third-highest official of the executive branch of the Federal Government of the United States, after the President and Vice President and is fourth in line to succeed the Presidency, coming after the Vice President, the Speaker of the House of Representatives, and the President pro tempore of the Senate. Six Secretaries of State have gone on to be elected President. Others, including John Kerry, William Seward, Henry Clay, William Jennings Bryan and Hillary Clinton have been unsuccessful presidential candidates, either before or after their term of office as Secretary of State.
The nature of the position means that Secretaries of State engage in travel around the world. The record for most countries visited in a secretary's tenure is 112 by Hillary Clinton.[10] Second is Madeleine Albright with 96.[11] The record for most air miles traveled in a secretary's tenure is 1.380 million miles by John Kerry.[12] Second is Condoleezza Rice's 1.059 million miles, and third is Clinton's 956,733 miles.[10]
What are the Qualifications of a Secretary of State? He ought to be a Man of universal Reading in Laws, Governments, History. Our whole terrestrial Universe ought to be summarily comprehended in his Mind.
“
”
—John Adams[13]
List of Secretaries of State[edit]
Further information: List of Secretaries of State of the United States
References[edit]
Jump up ^ "3 U.S. Code § 19 - Vacancy in offices of both President and Vice President; officers eligible to act". Cornell Law School.
Jump up ^ "Pay & Leave: Salaries & Wages". Salary Table No. 2015-EX. United States Office of Personnel Management. January 1, 2015. Retrieved January 4, 2016.
^ Jump up to: a b 5 U.S.C. § 5312.
Jump up ^ "Heads of State, Heads of Government, Ministers for Foreign Affairs", Protocol and Liaison Service, United Nations. Retrieved November 2, 2012.
Jump up ^ NATO Member Countries, NATO. Retrieved November 2, 2012.
Jump up ^ Cabinets and Counselors: The President and the Executive Branch (1997). Congressional Quarterly. p. 87.
Jump up ^ "Duties of the Secretary of State". U.S. Department of State. Retrieved 2017-02-01.
Jump up ^ "Duties of the Secretary of State of the United States". www.state.gov. United States Department of State. January 20, 2009. Retrieved March 28, 2010.
Jump up ^ "3 U.S. Code § 20 - Resignation or refusal of office".
^ Jump up to: a b Mark Landler (January 4, 2013). "Scare Adds to Fears That Clinton's Work Has Taken Toll". The New York Times.
Jump up ^ Lee, Matthew (June 28, 2012). "Frequent flier Hillary Clinton hits 100-country mark". Detroit Free Press. Associated Press. Archived from the original on June 28, 2012.
Jump up ^ Associated Press (April 6, 2016). "Kerry breaks record for miles traveled by secretary of state". Fox News.
Jump up ^ Ford, Worthington C., ed. (1927). Statesman and Friend: Correspondence of John Adams with Benjamin Waterhouse, 1784–1822. Boston, MA: Little, Brown, and Company. p. 57.
External links[edit]
Wikimedia Commons has media related to Secretaries of State of the United States.
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Official website
Current U.S. order of precedence (ceremonial)
Preceded by
Ambassadors from the United States
(while at their posts) Order of Precedence of the United States
as Secretary of State Succeeded by
Ambassadors to the United States
(in order of tenure)
Preceded by
Otherwise Barack Obama
as Former President Succeeded by
Otherwise António Guterres
as Secretary-General of the United Nations
Current U.S. presidential line of succession
Preceded by
President pro tempore of the Senate
Orrin Hatch 4th in line Succeeded by
Secretary of the Treasury
Steve Mnuchin
[show]
v
t
e
United States Secretaries of State
Secretary of Foreign Affairs
1781–89
R. Livingston
Jay
Secretary of State
1789–present
Jefferson
Randolph
Pickering
J. Marshall
Madison
Smith
Monroe
Adams
Clay
Van Buren
E. Livingston
McLane
Forsyth
Webster
Upshur
Calhoun
Buchanan
Clayton
Webster
Everett
Marcy
Cass
Black
Seward
Washburne
Fish
Evarts
Blaine
Frelinghuysen
Bayard
Blaine
Foster
Gresham
Olney
Sherman
Day
Hay
Root
Bacon
Knox
Bryan
Lansing
Colby
Hughes
Kellogg
Stimson
Hull
Stettinius
Byrnes
G. Marshall
Acheson
Dulles
Herter
Rusk
Rogers
Kissinger
Vance
Muskie
Haig
Shultz
Baker
Eagleburger
Christopher
Albright
Powell
Rice (tenure)
Clinton (tenure)
Kerry (tenure)
Tillerson
[show]
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Agencies under the United States Department of State
Headquarters: Harry S Truman Building
Rex Tillerson, Secretary of State
John Sullivan, Deputy Secretary of State and Deputy Secretary of State for Management and Resources
Tom Shannon, Under Secretary of State for Political Affairs
Deputy Secretary of State and
Deputy Secretary of State for Management and Resources
Counselor of the Department
Executive Secretariat
Office of U.S. Foreign Assistance Resources
Operations Center
Under Secretary for
Political Affairs
Bureau of African Affairs
Bureau of East Asian and Pacific Affairs
Bureau of European and Eurasian Affairs
Bureau of International Organization Affairs
Bureau of Near Eastern Affairs
Bureau of South and Central Asian Affairs
Bureau of Western Hemisphere Affairs
Under Secretary for
Economic Growth, Energy, and the Environment
Bureau of Economic and Business Affairs
Bureau of Energy Resources
Bureau of Oceans and International Environmental and Scientific Affairs
Office of the Science and Technology Adviser to the Secretary
Office of the Chief Economist
Under Secretary for
Arms Control and International Security Affairs
Bureau of Arms Control, Verification and Compliance
Bureau of International Security and Nonproliferation
Bureau of Political-Military Affairs
Under Secretary for
Public Diplomacy and Public Affairs
Bureau of Educational and Cultural Affairs
Bureau of Public Affairs
Bureau of International Information Programs
Department Spokesperson
Office of the Historian
Office of Policy, Planning, and Resources for Public Diplomacy and Public Affairs
United States Diplomacy Center
Under Secretary for
Management
Bureau of Administration
Bureau of Budget and Planning
Bureau of Consular Affairs
Bureau of Diplomatic Security
Bureau of Human Resources
Bureau of Information Resource Management
Bureau of Overseas Buildings Operations
Diplomatic Reception Rooms
Foreign Service Institute
Office of Children's Issues
Office of eDiplomacy
Office of Foreign Missions
Office of Management Policy, Rightsizing, and Innovation
Office of Medical Services
Office of White House Liaison
Under Secretary for
Civilian Security, Democracy, and Human Rights
Bureau of Conflict and Stabilization Operations
Bureau of Counterterrorism and Countering Violent Extremism
Bureau of Democracy, Human Rights, and Labor
Bureau of International Narcotics and Law Enforcement Affairs
Bureau of Population, Refugees, and Migration
Office of Global Criminal Justice
Office of Global Youth Issues
Office to Monitor and Combat Anti-Semitism
Office to Monitor and Combat Trafficking in Persons
Bureaus/Offices
reporting directly to the Secretary
Bureau of Intelligence and Research
Bureau of Legislative Affairs
Office of Civil Rights
Office of Inspector General
Office of the Legal Adviser
Office of Policy Planning Staff
Office of the Chief of Protocol
Office of Global Food Security
Office of Global Women's Issues
Office of the United States Global AIDS Coordinator
Office of Global Partnerships
[show]
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Leaders of the United States federal executive departments
Current
Agriculture
Commerce
Defense
Education
Energy
Health and Human Services
Homeland Security
Housing and Urban Development
Interior
Justice
Labor
State
Transportation
Treasury
Veterans Affairs
Past
Commerce and Labor
Health, Education, and Welfare
Navy
Post Office
War
[show]
v
t
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Presidential line of succession in the United States of America
Vice President (Mike Pence)
Speaker of the House of Representatives (Paul Ryan)
President pro tempore of the Senate (Orrin Hatch)
Secretary of State (Rex Tillerson)
Secretary of the Treasury (Steven Mnuchin)
Secretary of Defense (Jim Mattis)
Attorney General (Jeff Sessions)
Secretary of the Interior (Ryan Zinke)
Secretary of Agriculture (Sonny Perdue)
Secretary of Commerce (Wilbur Ross)
Secretary of Labor (Alex Acosta)
Secretary of Health and Human Services (Alex Azar)
Secretary of Housing and Urban Development (Ben Carson)
Secretary of Transportation (Elaine Chao[a])
Secretary of Energy (Rick Perry)
Secretary of Education (Betsy DeVos)
Secretary of Veterans Affairs (David Shulkin)
Secretary of Homeland Security (Kirstjen Nielsen)
Jump up ^ Although Elaine Chao is the current Secretary of Transportation, she is not a natural-born citizen (acquired U.S. citizenship by naturalization) and thus ineligible for the Presidency.
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text:
Hydraulic pump
From Wikipedia, the free encyclopedia
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Fluid flow in an external gear pump
Hydraulic pumps are used in hydraulic drive systems and can be hydrostatic or hydrodynamic. There is no since A hydraulic pump is a mechanical source of power that converts mechanical power into hydraulic energy (hydrostatic energy i.e. flow, pressure). It generates flow with enough power to overcome pressure induced by the load at the pump outlet. When a hydraulic pump operates, it creates a vacuum at the pump inlet, which forces liquid from the reservoir into the inlet line to the pump and by mechanical action delivers this liquid to the pump outlet and forces it into the hydraulic system. Hydrostatic pumps are positive displacement pumps while hydrodynamic pumps can be fixed displacement pumps, in which the displacement (flow through the pump per rotation of the pump) cannot be adjusted, or variable displacement pumps, which have a more complicated construction that allows the displacement to be adjusted. Although, hydrodynamic pumps are more frequent in day-to-day life. Hydrostatics pump which are of various types works on the principle of Pascal's law. It states that the increase in pressure at one point of the enclosed liquid in equilibrium of rest is transmitted equally to all other points of the liquid, unless the effect of gravity is neglected.(in case of statics)
Gearpump with external teeth, note the rotational direction of the gears.
Contents
[hide]
1 Hydraulic pump types
1.1 Gear pumps
1.2 Rotary vane pumps
1.3 Screw pumps
1.4 Bent axis pumps
1.5 Inline axial piston pumps and swashplate principle
1.6 Radial piston pumps
1.7 Peristaltic pumps
2 Pumps for open and closed systems
3 Multi-pump assembly
4 Hydraulic pumps, calculation formulas
4.1 Flow
4.2 Power
4.3 Mechanical efficiency
4.4 Hydraulic efficiency
5 References
6 External links
Hydraulic pump types[edit]
Gear pumps[edit]
Gearpump with internal teeth
Gear pumps (with external teeth) (fixed displacement) are simple and economical pumps. The swept volume or displacement of gear pumps for hydraulics will be between about 1 and 200 millilitres. They have the lowest volumetric efficiency ( η v ≈ 90 % {\displaystyle \eta _{v}\approx 90\%} ) of all three basic pump types (gear, vane and piston pumps)[1] These pumps create pressure through the meshing of the gear teeth, which forces fluid around the gears to pressurize the outlet side. For lubrication, the gear pump uses a small amount of oil from the pressurized side of the gears, bleeds this through the (typically) hydrodynamic bearings, and vents the same oil either to the low pressure side of the gears, or through a dedicated drain port on the pump housing. Some gear pumps can be quite noisy, compared to other types, but modern gear pumps are highly reliable and much quieter than older models. This is in part due to designs incorporating split gears, helical gear teeth and higher precision/quality tooth profiles that mesh and unmesh more smoothly, reducing pressure ripple and related detrimental problems. Another positive attribute of the gear pump, is that catastrophic breakdown is a lot less common than in most other types of hydraulic pumps. This is because the gears gradually wear down the housing and/or main bushings, reducing the volumetric efficiency of the pump gradually until it is all but useless. This often happens long before wear causes the unit to seize or break down.
A gerotor (image does not show intake or exhaust)
Rotary vane pumps[edit]
Fixed displacement vane pump
Rotary vane pumps (fixed and simple adjustable displacement) have higher efficiencies than gear pumps, but are also used for mid pressures up to 180 bar (18,000 kPa) in general. Modern units can exceed 300 bar (30,000 kPa) in continuous operation, although vane pumps are not regarded as "high pressure" components. Some types of vane pumps can change the centre of the vane body, so that a simple adjustable pump is obtained. These adjustable vane pumps are in general constant pressure or constant power pumps: the displacement is increased until the required pressure or power is reached and subsequently the displacement or swept volume is decreased until an equilibrium is reached. A critical element in vane pump design is how the vanes are pushed into contact with the pump housing, and how the vane tips are machined at this very point. Several type of "lip" designs are used, and the main objective is to provide a tight seal between the inside of the housing and the vane, and at the same time to minimize wear and metal-to-metal contact. Forcing the vane out of the rotating centre and towards the pump housing is accomplished using spring-loaded vanes, or more traditionally, vanes loaded hydrodynamically (via the pressurized system fluid).
Screw pumps[edit]
Principle of screw pump (Saugseite = intake, Druckseite = outflow)
Screw pumps (fixed displacement) consist of two Archimedes' screws that intermesh and are enclosed within the same chamber. These pumps are used for high flows at relatively low pressure (max 100 bars (10,000 kPa)).[clarification needed] They were used on board ships where a constant pressure hydraulic system extended through the whole ship, especially to control ball valves[clarification needed] but also to help drive the steering gear and other systems. The advantage of the screw pumps is the low sound level of these pumps; however, the efficiency is not high.
The major problem of screw pumps is that the hydraulic reaction force is transmitted in a direction that's axially opposed to the direction of the flow.
There are two ways to overcome this problem:
put a thrust bearing beneath each rotor;
create a hydraulic balance by directing a hydraulic force to a piston under the rotor.
Types of screw pumps:
single end
double end
single rotor
multi rotor timed
multi rotor untimed.
Bent axis pumps[edit]
Bent axis pumps, axial piston pumps and motors using the bent axis principle, fixed or adjustable displacement, exists in two different basic designs. The Thoma-principle (engineer Hans Thoma, Germany, patent 1935) with max 25 degrees angle and the Wahlmark-principle (Gunnar Axel Wahlmark, patent 1960) with spherical-shaped pistons in one piece with the piston rod, piston rings, and maximum 40 degrees between the driveshaft centreline and pistons (Volvo Hydraulics Co.). These have the best efficiency of all pumps. Although in general the largest displacements are approximately one litre per revolution, if necessary a two-liter swept volume pump can be built. Often variable-displacement pumps are used, so that the oil flow can be adjusted carefully. These pumps can in general work with a working pressure of up to 350–420 bars in continuous work.
Inline axial piston pumps and swashplate principle[edit]
Axial piston pump, swashplate principle
Axial piston pumps using the swashplate principle (fixed and adjustable displacement) have a quality that is almost the same as the bent axis model. They have the advantage of being more compact in design and also allow use of "through-drive" series mounted auxiliary rotating equipment, based on their in-line design. The pumps are easier and more economical to manufacture; the disadvantage is that they are more sensitive to oil contamination. The axial piston pump is likely the most widely used variable displacement type, being found in everything from heavy industrial to mobile applications. By using different compensation techniques, the variable displacement type of these pumps can continuously alter fluid discharge per revolution and system pressure based on load requirements, maximum pressure cut-off settings, horsepower/ratio control, and even fully electroproportional systems, requiring no other input than electrical signals. This makes them potentially hugely power saving compared to other constant flow pumps in systems where prime mover/diesel/electric motor rotational speed is constant and required fluid flow is non-constant.
Radial piston pumps[edit]
Radial piston pump
Radial piston pumps are used especially for high pressure and relatively small flows. Pressures of up to 650 bar are normal. In fact variable displacement is possible. The pump is designed in such a way that the plungers are connected to a floating ring. This floating ring can be moved horizontally by a control lever & thus causes an eccentricity in the centre of rotation of the plungers. The amount of eccentricity can be controlled to vary the discharge. The suction & discharge can be totally reversed seamlessly by shifting the eccentricity to the opposite side. Hence both quantity & direction can be varied in a radial piston pump, just as in the Swash plate pump.
Peristaltic pumps[edit]
Peristaltic pumps are not generally used for high pressures.
Pumps for open and closed systems[edit]
Most pumps are working in open systems. The pump draws oil from a reservoir at atmospheric pressure. It is very important that there is no cavitation at the suction side of the pump. For this reason the connection of the suction side of the pump is larger in diameter than the connection of the pressure side. In case of the use of multi-pump assemblies, the suction connection of the pump is often combined. It is preferred to have free flow to the pump (pressure at inlet of pump at least 0.8 bar). The body of the pump is often in open connection with the suction side of the pump.
In case of a closed system, both sides of the pump can be at high pressure. The reservoir is often pressurized with 6-20 bars boost pressure. For closed loop systems, normally axial piston pumps are used. Because both sides are pressurized, the body of the pump needs a separate leakage connection.
Multi-pump assembly[edit]
In a hydraulic installation, one pump can serve several cylinders and motors. However, in that case a constant pressure system is required and the system always needs full power. It is more economic to give each cylinder and motor its own pump. In that case, multi-pump assemblies can be used. Gear pumps are often supplied as multi-pumps. The different chambers (sometimes of different sizes) are mounted in one body or built together. Vane pumps and gerotor pumps too are often available as multi-pumps. Screw pumps can be combined with gear or vane pumps. Axial piston swashplate pumps can be combined with a second pump, or with one or more gear pumps or vane pumps (the gear or vane pumps often serving as flush pumps for cooling larger units). Axial plunger pumps of the bent-axis design cannot be combined with other pumps.
Hydraulic pumps, calculation formulas[edit]
Flow[edit]
Q = n ⋅ V stroke ⋅ η vol {\displaystyle Q=n\cdot V_{\text{stroke}}\cdot \eta _{\text{vol}}}
where
Q {\displaystyle \scriptstyle Q} , flow (m3/s)
n {\displaystyle \scriptstyle n} , stroke frequency (Hz)
V stroke {\displaystyle \scriptstyle V_{\text{stroke}}} , stroked volume (m3)
η vol {\displaystyle \scriptstyle \eta _{\text{vol}}} , volumetric efficiency
Power[edit]
P = n ⋅ V stroke ⋅ Δ p η mech {\displaystyle P={n\cdot V_{\text{stroke}}\cdot \Delta p \over \eta _{\text{mech}}}}
where
P {\displaystyle \scriptstyle P} , power (W)
n {\displaystyle \scriptstyle n} , stroke frequency (Hz)
V stroke {\displaystyle \scriptstyle V_{\text{stroke}}} , stroked volume (m3)
Δ p {\displaystyle \scriptstyle \Delta p} , pressure difference over pump (Pa)
η mech,hydr {\displaystyle \scriptstyle \eta _{\text{mech,hydr}}} , mechanical/hydraulic efficiency
Mechanical efficiency[edit]
n mech = T theoretical T actual ⋅ 100 % {\displaystyle n_{\text{mech}}={T_{\text{theoretical}} \over T_{\text{actual}}}\cdot 100\%}
where
n mech {\displaystyle \scriptstyle n_{\text{mech}}} , mechanical pump efficiency percent
T theoretical {\displaystyle \scriptstyle T_{\text{theoretical}}} , theoretical torque to drive
T actual {\displaystyle \scriptstyle T_{\text{actual}}} , actual torque to drive
Hydraulic efficiency[edit]
n h y d r = Q a c t u a l Q t h e o r e t i c a l ⋅ 100 % {\displaystyle n_{hydr}={Q_{actual} \over Q_{theoretical}}\cdot 100\%}
where
n h y d r {\displaystyle \scriptstyle n_{hydr}} , hydraulic pump efficiency
Q t h e o r e t i c a l {\displaystyle \scriptstyle Q_{theoretical}} , theoretical flow rate output
Q a c t u a l {\displaystyle \scriptstyle Q_{actual}} , actual flow rate output
References[edit]
Jump up ^ Parr, Andrew (2011). "Hydraulics and Pneumatics a technician's and engineer's guide", p. 38. Elsevier.
External links[edit]
Wikimedia Commons has media related to Gear pump.
External gear pump description
Internal gear pump description
Wikimedia Commons has media related to Mechanical efficiency.
Mechanical efficiency description
Hydraulic efficiency description
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