omniomni/omni-engineering huggingface dataset:
Trash rack. A trash rack (US) or debris screen is a wooden or metal structure, frequently supported by masonry, that prevents water-borne debris (such as logs, boats, animals, masses of cut waterweed, etc.) from entering the intake of a water mill, pumping station or water conveyance. This protects water wheels, penstocks, and sluice gates from destruction during floods. They are sometimes fitted to storm drain inflows and outflows to prevent debris from entering a natural watercourse. Other names used as trash screen (US) or debris grille.

Trash racks composed of vertical wooden strakes separated by narrow gaps are very common and perform extremely poorly. Metal gratings are sturdier and can have narrower strakes, and angling the trash rack properly can allow some self-cleaning from the action of the water. Modern trash racks as used by hydroelectric plants can incorporate such advanced features as wedge-wire screens, the Coanda effect, and cleaning robots.

In waterways with large amounts of floating debris, various permanently installed "trash rakes" may be required to reduce the labor required for regular cleaning. 

Trash racks are designed for water velocity of around 2 feet/second (0.6 metres/second) to prevent excessive energy loss due to the head loss across the trash rack. Close spacing keeps out more small floating debris or fish, but may plug up easily with frazil ice in cold climates.

References

Watermills
GWR 3100 Class. The Great Western Railway (GWR) 3100 Class was a class of 2-6-2T side tank steam locomotive.

History 
This class of large prairie was created in 1938  when Collett rebuilt some of Churchward's  3150 Class with a view to using them as bankers, particularly from Severn Tunnel Junction shed. These engines used the standard class 4 boiler again, but pressed to . and using smaller coupled wheels of  diameter, and  increase in cylinder diameter, nominal tractive effort rose to . Almost impossible to pick out was a  reduction in pony truck wheel diameter to . Only five engines were ever modified, namely 3173, 3156, 3181, 3155 and 3179 which were rebuilt as 3100 to 3104 respectively. None of these were preserved.

See also
GWR 3100/5100 Class (1906)
GWR 3150 Class
GWR 5101 Class
GWR 6100 Class
GWR 8100 Class
List of GWR standard classes with two outside cylinders

References

External links  
Class 3100 Details at Rail UK

2-6-2T locomotives
3100
Railway locomotives introduced in 1938
Scrapped locomotives
Standard gauge steam locomotives of Great Britain
Lloyd Stearman. Lloyd Carlton Stearman (October 26, 1898 – April 3, 1975) was an American aviator, aircraft designer, and early aviation entrepreneur.

Biography
Stearman was born in Wellsford, Kansas. From 1917 – 1918, he attended Kansas State College (later renamed Kansas State University) in Manhattan, Kansas, where he studied engineering and architecture.  In 1918, he left school to enlist in the U.S. Naval Reserve in San Diego, California; while there he learned to fly Curtiss N-9 seaplanes.

During the mid-1920s Matty Laird, designer of the Laird Swallow aircraft, hired Stearman as a mechanic, giving him his first exposure to fixed-wing aircraft manufacturing. In 1925, Stearman and Walter Beech teamed up with Clyde Cessna to form the Travel Air Manufacturing Company. In 1926, Stearman left to form his own manufacturing company in California, Stearman Aircraft. In 1927, he moved the company back to Wichita. 

Following World War II, many Stearman PT-13 primary trainers were converted to agricultural aircraft; In 1948 more than 4,345 Stearman aircraft were used in agricultural flying.

In 1929, Stearman Aircraft merged with Boeing Airplane Co., Boeing Aircraft of Canada, Varney Airlines, National Air Transport, Pacific Air Transport, Boeing Air Transport, Hamilton Standard Propeller, Sikorsky, Pratt & Whitney, Chance Vought, Northrop and United Airports of Connecticut to become United Aircraft and Transport Corporation, owned by William Boeing. Stearman held the position of President of the Stearman Division until 1930, followed by his resignation in 1931.

In 1932, Stearman, Robert Gross, Walter Varney and others, bought Lockheed Aircraft Company. Stearman was named president and Carl B. Squier vice president. 

In 1935, Stearman resigned from Lockheed, and from 1936 through 1938, partnered with Dean Hammond to form the Stearman-Hammond Aircraft Corporation to produce the Stearman-Hammond Y-1. In 1955, Stearman rejoined Lockheed as an engineer, where he retired in 1968.

Stearman died of cancer on April 3, 1975, at home in Northridge, Los Angeles.

Legacy
In recognition of his contributions to the aircraft industry, Lloyd Stearman was inducted into the National Aviation Hall of Fame in Dayton, Ohio in July 1989.

References

External links
 Lloyd Stearman-Aviator, Engineer and Kansan
 The First Stearman

1898 births
1975 deaths
American aviation businesspeople
Aviators from Kansas
American aviation pioneers
Kansas State University alumni
People from Wellsville, Kansas
National Aviation Hall of Fame inductees
United States Navy personnel of World War I
Deaths from cancer in California
United States Navy reservists
Kansas Business Hall of Fame inductees
DSV Sea Cliff. DSV-4 (formerly known as Sea Cliff) is a 25-ton, crewed deep-ocean research submersible owned by the United States Navy, now known only by its hull number, not by its former name.

DSV-4 is an Alvin-class deep submergence vehicle (DSV), a sister ship to Turtle (DSV-3) and Alvin (DSV-2). The Alvin-class DSVs were designed to replace older DSVs, such as the less-maneuverable Trieste-class bathyscaphes.  Sea Cliff was built by Electric Boat in Groton, Connecticut for the U.S. Navy and was completed in December 1968. It spent much of its service life on loan to the Woods Hole Oceanographic Institution.

DSV-4 initially had a maximum dive depth of ; all Alvin-class personnel pressure hulls were originally designed for , but subsequent testing allowed a higher rating. In 1981, the submersible was refitted with a titanium personnel hull to dive to . With the refit of DSV-4, the bathyscaphe DSV-1 (formerly known as Trieste II) was retired from service.

In 1985 the Sea Cliff made a record dive for this vessel type by diving 20,000 feet off Guatemala's Pacific Coast. The crew of the dive consisted of NAVSEA system certification representative/command pilot, LCDR Rick Williams, mission pilot Lt. Alan Mason, and co-pilot Chief Petty Officer David Atchinson. From late September to early October 1990, over a course of 6 days, DSV-4 recovered the cargo door of United Airlines Flight 811 from the Pacific Ocean.

DSV-4 has a plug hatch  in diameter, held in place mechanically with hatch dogs and, while submerged, by the pressure of the water above it.

Sea Cliff was retired from active service in 1998 and subsequently given to Woods Hole Oceanographic Institution (WHOI). As of 2019, the Naval Vessel Register shows DSV-4 was returned to active U.S. Navy service on September 30, 2002, in the custody of Woods Hole.

Although an article in The New York Times from 1998 indicated that DSV-4 would be cannibalized to upgrade Alvin, this appears to not have taken place since: 1) the US Navy Vessel Registry shows DSV-4 as an active vessel; 2) a photo from 2005 shows DSV-4 to still be intact with its personnel pressure sphere; and 3) WHOI in its official history of Alvin does not discuss using DSV-4 parts during this timeframe. As of September 2023, WHOI does not list DSV-4 as one of their underwater vehicles.

Awards
Meritorious Unit Citation with three stars
Navy E Ribbon (2 awards)
National Defense Service Medal with two stars
Global War on Terrorism Service Medal

See also

References
 *

External links
 Deep Submergence Vehicles article at the Federation of American Scientists web page

Sea Cliff
Research submarines of the United States
1968 ships
AGM-136 Tacit Rainbow. The AGM-136A Tacit Rainbow was a United States military anti-radiation missile program run from 1982 to 1991.

The requirement was for a low-cost air-launchable system to aid in the destruction of enemy air defense networks. The proposed unit would combine elements of cruise missiles and UAVs, it would be launched in large numbers by heavy bombers, fighters, or possibly mass ground launch systems. 

The missiles would fly in advance of crewed aircraft up to  to pre-programmed target zones and patrol there until enemy radar sources were detected which would then be destroyed, acting as a loitering munition. This extended patrol time on target ("loiter time") was the key feature of the new system, a persistent anti-radiation missile (PARM) as opposed to a HARM. This would allow for the threatening suppressive effects that HARMs have for significantly longer times, allowing friendly aircraft to operate in the area with a higher degree of safety for a longer time.

The project was started by the DoD in 1982, but moved to the control of the USAF Aeronautical Systems Division in 1984 as a joint Navy/Air Force project. The majority of the system was designed and developed by Northrop with Texas Instruments providing the seek head and Boeing providing a system that allowed it to be launched from B-52 bombers. The first test air-launch was on July 30, 1984.

The unit was  long and  in span with a body diameter of , flight and control surfaces deployed after launch. It weighed around  including the  warhead. Power was provided by a Williams F121 turbofan, producing   of thrust from the ,  unit. 

Some sources state that production units would have used a  variant of the Williams International WR-24. While achieved speed and range are uncertain, low subsonic speed flight was probable and all sources indicate a range much lower than the hoped-for . Each unit was to cost around $200,000, up to thirty would have been loaded in a single B-52.

The Naval Research Advisory Committee reported in 1989 that the project was not progressing well. In 1991 a DoD audit found numerous management problems. The program was canceled in 1991 (FY 1992), without any production units and at a total cost of around $4 billion. It was only the second post-Vietnam military project to be canceled after completing testing but before production.

Survivors

Below is a list of museums which have a Tacit Rainbow in their collection:
Museum of Aviation, Robins Air Force Base, Georgia
 National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio
 U.S. Naval Museum of Armament & Technology, NAWS China Lake, California

References

External links
Global security article
AGM-136 on APA
Directory of U.S. Military Rockets and Missiles

AGM-136
AGM-136
Abandoned military rocket and missile projects of the United States
MacMach. MacMach is a computer operating system from the early 1990s, developed by Carnegie Mellon University. Architecturally, it consists of Berkeley Software Distribution (BSD) 4.3 code running on the Mach microkernel, with the Apple Macintosh System 7 running experimentally as a Mach task. The entire system runs on Macintoshes based on the Motorola 68000 series (68k) family of microprocessors. Its license requires the user to have an AT&T UNIX license, and includes Apple, Inc.'s restriction against further redistribution.

See also 
 MkLinux
 MachTen
 A/UX
 NeXTSTEP

References

Berkeley Software Distribution
Mach (kernel)
Microkernel-based operating systems
Microkernels
Meridian Mail. Meridian Mail is one of the early all-digital voicemail systems, running on Meridian1 / SL-1 digital PBX systems from Northern Telecom (later known as Nortel).

In the early 1980s Northern Telecom introduced the Norstar. The Norstar was the first all-digital system suitable for small-sized offices (up to 192 lines), and became one of their major product lines.

The Norstar is powered by a 16 MHz Motorola 68000, and uses only a fraction of the CPU's power. Nortel executives were interested in finding ways to use that excess power, as long as their customers paid for the privilege. Nortel asked their research arm, Bell Northern Research (BNR), to look for ways to spend those cycles. Meridian Mail was developed as a result.

Meridian Mail was discontinued by Nortel, and has been replaced by CallPilot, which in fact uses the same features and codes as Meridian Mail, but unlike Meridian Mail, allows newer features such as Unified Messaging. Unlike older Nortel systems, where the Meridian PBXs were assigned Meridian Mail and the Norstar systems were assigned Norstar VoiceMail or Startalk Flash VoiceMail, CallPilot was branded for both the Communication Servers PBX and Business Communication Manager Hybrid/Key telephone systems.

CallPilot is one of the products acquired by Avaya in their purchase of Nortel Enterprise Solutions in 2009.

See also
Unified messaging
LANstar - Northern Telecom's foray into twisted-pair PC networking

References

External links
Meridian Mail

Nortel
Telephone service enhanced features
Voicemail
Nortel products
Ellicott's Stone. Ellicott's Stone, also known as the Ellicott Stone, is a boundary marker in northern Mobile County, Alabama.  It was placed on April 10, 1799, by a joint U.S.-Spanish survey party headed by Andrew Ellicott. It was designated by the American Society of Civil Engineers as a Historic Civil Engineering Landmark in 1968 and was added to the National Register of Historic Places on April 11, 1973.

It is the only known stone monument set by Ellicott when he surveyed the 31st parallel north latitude, which served as the boundary line between the  Mississippi Territory in the United States and Spanish West Florida. The boundary line extended along the 31st parallel from the Mississippi River east to the Chattahoochee River, as set forth in the 1795 Pinckney Treaty, formally known as the Treaty of San Lorenzo.

Ellicott's Stone is the initial point for all United States Public Land surveys in the southern region of Alabama and Mississippi. It is the point of intersection of what is known today as the St. Stephens meridian and the St. Stephens baseline. All townships in the area are numbered from the stone.

The marker stone is located east of U.S. Route 43 in  Ellicott Stone Historical Park, about  south of Bucks, Alabama. The park was established in 1917. It is now near the James M. Barry Electric Generating Plant, west of the Mobile River.

Description
The stone marker, a ferruginous sandstone block about two feet high and eight inches (203 mm)  thick, is near the west bank of the Mobile River. On the northern side of the stone is an inscription stating "U.S. Lat. 31, 1799."  The inscription on the southern side reads "Dominio De S.M. Carlos IV, Lat. 31, 1799." (Dominion of his majesty King Charles IV, Lat. 31, 1799)

References

External links

1799 establishments in the United States
1799 in the United States
Historic Civil Engineering Landmarks
Pre-statehood history of Alabama
Historic surveying landmarks in the United States
Monuments and memorials in Alabama
National Register of Historic Places in Mobile County, Alabama
Control bus. In computer architecture,
a control bus is part of the system bus and is used by CPUs for communicating with other devices within the computer. While the address bus carries the information about the device with which the CPU is communicating and the data bus carries the actual data being processed, the control bus carries commands from the CPU and returns status signals from the devices. For example, if the data is being read or written to the device the appropriate line (read or write) will be active (logic one).

Lines 
The number and type of lines in a control bus varies but there are basic lines common to all microprocessors, such as:
 Read (). A single line that when active (logic zero) indicates the device is being read by the CPU.
 Write (). A single line that when active (logic zero) indicates the device is being written by the CPU.
 Byte enable (). A group of lines that indicate the size of the data (8, 16, 32, 64 bytes).

The RD and WR signals of the control bus control the reading or writing of RAM, avoiding bus contention on the data bus.

Additional lines are microprocessor-dependent, such as:

 Transfer ACK ("acknowledgement"). Delivers information that the data was acknowledged (read) by the device.
 Bus request (BR, BREQ, or BRQ). Indicates a device is requesting the use of the (data) bus.
 Bus grant (BG or BGRT). Indicates the CPU has granted access to the bus.
 Interrupt request (IRQ). A device with lower priority is requesting access to the CPU.
 Clock signals. The signal on this line is used to synchronize data between the CPU and a device.
 Reset. If this line is active, the CPU will perform a hard reboot.

Systems that have more than one bus master have additional control bus signals that control which bus master drives the address bus, avoiding bus contention on the address bus.

See also
Address bus
Data bus
Bus mastering

References

External links
Definition by Webopedia.
Computer system organization at the University of California, Riverside.
"Hardware and Software Architecture", a PowerPoint presentation at California State University, Los Angeles.

Computer buses
David Criswell. David R. Criswell (July 17, 1941 – September 10, 2019) was the Director of the Institute for Space Systems Operations at the University of Houston.  ISSO is the operational agent for the Houston Partnership for Space Exploration.

Criswell received a Bachelor of Science degree in 1963 (graduating cum laude) and a Master of Science degree in Physics in 1964 from the University of North Texas, in Denton, Texas.  In 1968, he received a Doctorate degree in space physics and Astronomy from Rice University in Houston, Texas.

He was an active member of the Power from Space Committee of the International Astronautical Federation and participated in IAF and United Nations Summits dealing with supplying energy to Earth.  He also served on the Board of Governors of the National Space Society, a non-profit space advocacy organization in Washington, D.C.

Views on exploiting lunar resources

For over thirty years, Criswell was an advocate for obtaining solar power from the Moon.  He proposed the large-scale construction of solar collectors on the lunar surface, using local lunar materials.  The solar energy would be converted to microwave energy and transmitted to Earth.

Criswell envisioned that this energy source would spur an unprecedented amount of global economic growth (Gross World Product increasing by a factor of 10), while having a positive environmental impact (fossil fuel-burning power plants would be decommissioned).  He pointed out that lunar-solar energy would not generate nuclear waste, and is not a finite resource (in the sense that fossil fuels are a finite resource).

He estimated that a 1 GigaWatt demo of the lunar-solar power generation system could be built over a 10-year period for approximately $60 billion in 1990 dollars.  (For comparison, the 1.65 GW Benban Solar Park in Egypt cost $4 billion in 2019; however, Benban's delivered power is 430 MW compared to the 1 GW demo which would deliver a full 1 GW.)

In short, Criswell believed that lunar-solar energy is the only viable option for generating the massive amounts of electrical power that would be needed to raise the standard of living in third-world nations to that of first-world nations.

He once said, from the University of Houston, that "We are already well beyond what the biosphere can provide. We have to go outside to get something else."

See also
Future energy development
Solar power satellite
In-Situ Resource Utilization

Further reading
Interstellar Migration and the Human Experience, Chapter 4: Solar System Industrialization, by David R. Criswel
Star lifting

References

External links
 Testimony of Dr. David R. Criswell: Senate Hearing on "Lunar Exploration"
 Lunar Solar Power (LSP) System: Practical Means to Power Sustainable Prosperity
 Interview with David Criswell
 Audio Interview with David Criswell in 2005
 C-SPAN Video 1997 - Starts at 02h:35mn

American planetary scientists
Space advocates
University of North Texas alumni
Rice University alumni
University of Houston faculty
1941 births
2019 deaths
NeXTcube. The NeXTcube is a high-end workstation computer developed, manufactured, and sold by NeXT from 1990 to 1993. It superseded the original NeXT Computer workstation and is housed in a similar cube-shaped magnesium enclosure, designed by frog design. The workstation runs the NeXTSTEP operating system and was launched with a  list price.

Hardware
The NeXTcube is the successor to the original NeXT Computer, with a 68040 processor, a hard disk in place of the magneto-optical drive, and a floppy disk drive. NeXT offered a 68040 system board upgrade (and NeXTSTEP 2.0) for . A 33 MHz NeXTcube Turbo was later produced.

NeXT released the NeXTdimension for the NeXTcube, a circuit board based on an Intel i860 processor, which offers 32-bit PostScript color display and video-sampling features.

The Pyro accelerator board replaces the standard 25 MHz processor with a 50 MHz one.

Specifications

 
 Display: 1120×832 17 in (432 mm) 82 ppi grayscale MegaPixel Display
 Operating system: NeXTSTEP 2.2 Extended or later
 CPU: 25 MHz 68040 with integrated floating-point unit
 Digital signal processor: 25 MHz Motorola DSP56001
 RAM: 8 MB, expandable to 64 MB (Sixteen 30-pin SIMM slots)
 Floppy drive: 2.88 MB
 Hard drive: 105 MB, 340 MB, 400 MB, 660 MB, 1.4 GB or 2.8 GB SCSI drive
 Network interface: 10BASE-T and 10BASE2 Ethernet
 Expansion: four NeXTbus slots (mainboard uses one slot)
 Size (H × W × D): 12 in × 12 in × 12 in (305 mm x 305 mm x 305 mm (±1 mm))

Legacy

Tim Berners-Lee created the World Wide Web at CERN in Switzerland on the NeXTcube workstation in 1990.

See also
 NeXT character set
 NeXTcube Turbo
 NeXTstation
 Power Mac G4 Cube, a similar cube computer from Apple

References

External links

Computer workstations
NeXT
History of the Internet
Steve Jobs
68k-based computers
Autovent. An autovent is a device for maintaining a greenhouse or conservatory within a range of temperatures.  The basic principle is that as greenhouse heats above ambient the air inside becomes lighter, the vent opens when a certain temperature is reached and lets the hot air out - drawing cooler air in from outside.

Mechanism
The force to open the vent is provided a number of ways, the most common being through thermal expansion and by electric motors.  Thermal expansion based actuators use either the differential expansion rate of different materials (bimetallic strips) or special fluids with large coefficient of thermal expansion in pistons.  This approach is cheap, reliable and passive (requires no external energy).

Electric motors (usually servo motors) are usually controlled by an electronic sensor, and can be more accurately programmed.  The vents can form part of a more complex climate control system for controlling humidity, fresh air rate and temperature.  The most sophisticated systems use a dedicated computer to control watering, cooling (usually evaporative cooling), heating, lighting, CO2 injection fertilization and air flow.

Heating, ventilation, and air conditioning