omniomni/omni-engineering huggingface dataset:
Next Objective. Next Objective was the name of a Boeing B-29-36-MO Superfortress, 44-27299, Victor 86, modified to carry the atomic bomb in World War II.

Airplane history
Assigned to the 393d Bomb Squadron, 509th Composite Group, it was one of 15 Silverplate B-29s used by the 509th. Next Objective was built at the Glenn L. Martin Aircraft Plant at Omaha, Nebraska, as a Block 35 aircraft. It was one of 10 modified as a Silverplate and re-designated "Block 36". Delivered on 20 March 1945, to the USAAF, it was assigned to crew A-3 (1st Lt. Ralph N. Devore, aircraft commander) and flown to Wendover Army Air Field, Utah. It left Wendover on 11 June 1945 for North Field, Tinian and arrived 17 June.

It was originally assigned the Victor (unit-assigned identification) number 6 but on 1 August was given the triangle N tail markings of the 444th Bomb Group as a security measure and had its Victor changed to 86 to avoid misidentification with actual 444th BG aircraft. It was named Next Objective and its nose art applied after the atomic bomb missions. 

While at Tinian, Devore and crew A-3 flew Next Objective on 12 practice bombing missions and three pumpkin bomb missions against Japanese industrial targets at Toyama, Niihama, and Nagoya, and one which was aborted. Major Charles Sweeney, commanding officer of the 393d BS, used the bomber to rehearse procedures using a dummy "Little Boy" test assembly on 26 and 29 July.  On the latter mission Next Objective landed on Iwo Jima where the inert bomb was unloaded, then reloaded to practice a contingency in which a spare aircraft would take over the mission.

In November 1945 it returned with the 509th to Roswell Army Air Field, New Mexico. From March to August 1946 it was assigned to the Operation Crossroads task force, then rejoined the 509th BG at Roswell. In April 1949 Next Objective was transferred to the 97th Bomb Group at Biggs Air Force Base, Texas.

On 25 May 1949, 44-27299 was assigned to a navigation training mission. Shortly after takeoff an engine fire broke out in the right outboard engine, resulting in a crew bailout. The navigator assigned struck his head on the machinery that operated the nose landing gear as he exited the aircraft and was killed when his parachute did not deploy. The pilotless Next Objective circled in a two-mile orbit before crashing 35 miles northeast of El Paso, where it exploded on impact.

Other aircraft named Next Objective
Two FB-111A strategic bombers of the USAF 509th Bomb Wing, serials 68-0257 and 68-0284, carried the name Next Objective on their nosewheel doors, and 68-0257 carried the B-29 nose art, while based at Pease Air Force Base, New Hampshire, in the 1970s and 1980s.

External links
   Color image of Next Objective nose art

Sources
 Campbell, Richard H., The Silverplate Bombers: A History and Registry of the Enola Gay and Other B-29s Configured to Carry Atomic Bombs (2005),  
 509th CG Aircraft Page, MPHPA

Next Objective
Entropy rate. In the mathematical theory of probability, the entropy rate or source information rate is a function assigning an entropy to a stochastic process.

For a strongly stationary process, the conditional entropy for latest random variable eventually tend towards this rate value.

Definition 
A process  with a countable index gives rise to the sequence of its joint entropies . If the limit exists, the entropy rate is defined as

Note that given any sequence  with  and letting , by telescoping one has . The entropy rate thus computes the mean of the first  such entropy changes, with  going to infinity.
The behaviour of joint entropies from one index to the next is also explicitly subject in some characterizations of entropy.

Discussion 
While  may be understood as a sequence of random variables, the entropy rate  represents the average entropy change per one random variable, in the long term. 

It can be thought of as a general property of stochastic sources - this is the subject of the asymptotic equipartition property.

For strongly stationary processes 
A stochastic process also gives rise to a sequence of conditional entropies, comprising more and more random variables.
For strongly stationary stochastic processes, the entropy rate equals the limit of that sequence

The quantity given by the limit on the right is also denoted , which is motivated to the extent that here this is then again a rate associated with the process, in the above sense.

For Markov chains 
Since a stochastic process defined by a Markov chain that is irreducible, aperiodic
and positive recurrent has a stationary distribution, the entropy rate is independent of the initial distribution.

For example, consider a Markov chain defined on a countable number of states. Given its right stochastic transition matrix  and an entropy

associated with each state, one finds

where  is the asymptotic distribution of the chain.

In particular, it follows that the entropy rate of an i.i.d. stochastic process is the same as the entropy of any individual member in the process.

For hidden Markov models 
The entropy rate of hidden Markov models (HMM) has no known closed-form solution. However, it has known upper and lower bounds. Let the underlying Markov chain  be stationary, and let  be the observable states, then we haveand at the limit of , both sides converge to the middle.

Applications 
The entropy rate may be used to estimate the complexity of stochastic processes. It is used in diverse applications ranging from characterizing the complexity of languages, blind source separation, through to optimizing quantizers and data compression algorithms. For example, a maximum entropy rate criterion may be used for feature selection in machine learning.

See also
 Information source (mathematics)
 Markov information source
 Asymptotic equipartition property
 Maximal entropy random walk - chosen to maximize entropy rate

References

 Cover, T. and Thomas, J. (1991) Elements of Information Theory, John Wiley and Sons, Inc.,  

Information theory
Entropy
Markov models
Temporal rates
Fiat CR.1. The Fiat CR.1 was an Italian biplane fighter aircraft of the 1920s. Of wood-and-fabric construction, it was designed by Celestino Rosatelli, from whom it gained the 'CR' designation. Its most distinctive feature was that the lower wings were longer than the upper ones.

Design and development

Regia Aeronautica requested two prototype aircraft from Fiat in the early 1920s. The results were designated MM.1 and MM.2, identical except for the rudder (one had a rounded, counterbalanced rudder) and engines (they had differing marks of Hispano-Suiza piston engines).

The aircraft was a biplane of conventional layout, with fixed tailskid landing gear and an open cockpit, with the pilot's head aligned with the trailing edge of the upper wing. The V8 engine powered a fixed-pitch two-blade wooden propeller. The landing gear had a fixed axle between the wheels. It carried two synchronized 7.7 mm (.303 in) Vickers machine guns firing through the propeller arc.

The two prototypes were evaluated against another biplane fighter, the SIAI S.52, and proved superior in manoeuvrability and top speed. Accordingly, contracts were issued to three Italian companies for three batches of production aircraft, to be designated CR.1:
109 units to be built by Fiat.
 40 units to be built by OFM of Napoli.
100 units to be built by SIAI.

After two preproduction prototypes were again flight tested, a total of 240 units were placed in Italian military service, beginning in 1925.

Operational history

The Regia Aeronautica ordered 240 CR.1s and began equipping its 1st Fighter
Group in 1924. By 1926, 12 Italian fighter squadrons had been allocated the aircraft. In the same year, Fiat introduced an updated all-metal version, the CR.20.

Though both Belgium and Poland evaluated and rejected the aircraft, an export order was received from Latvia. Their nine CR.1s, fitted with the 224 kW (300 hp) Hispano-Suiza HS8N8 engine, served in Latvian Naval Aviation until 1936.

In the 1930s, some CR.1s were fitted with Isotta Fraschini Asso Caccia engines of 328 kW (440 hp), which improved their performance. These units were given to 163 Squadriglia, based at Rhodes in the Aegean Sea. Those units were withdrawn from active service in 1937.

Operators

Regia Aeronautica

Latvian Air Force
Latvian Navy

Specifications (CR.1)

See also

References

External links

 Fiat CR.1 (Spanish)

CR.01
Biplanes
Single-engined tractor aircraft
1920s Italian fighter aircraft
Aircraft with fixed conventional landing gear
Single-engined piston aircraft
High-energy-density matter. High-energy-density matter (HEDM) is a class of energetic materials, particularly fuel, with a high ratio of potential chemical energy output to density, usually termed "thrust-to-weight ratio", hence "high energy density".  The substances are extremely reactive, therefore potentially dangerous, and some consider them impractical.  Researchers are looking into HEDM that can provide much more lift than the current liquid hydrogen-liquid oxygen reactions used in today's spacecraft.

See also
Energy density
Oxygen rings

References 
https://fas.org/spp/military/docops/usaf/2020/app-i.htm 

Energy storage
Fuels
Street gutter. A street gutter is a depression that runs parallel to a road and is designed to collect rainwater that flows along the street diverting it into a storm drain. A gutter alleviates water buildup on a street, allows pedestrians to pass without walking through puddles, and reduces the risk of hydroplaning by road vehicles. When a curbstone is present, a gutter may be formed by the convergence of the road surface and the vertical face of the sidewalk; otherwise, a dedicated gutter surface made of concrete may be present. Depending on local regulations, a gutter usually discharges, as a nonpoint pollution source in a storm drain whose final discharge falls into a detention pond (in order to remove some pollutants by sedimentation) or into a body of water. Street gutters are most often found in areas of a city which have high pedestrian traffic. In rural areas, gutters are seldom used and are frequently replaced by a borrow ditch.

In past centuries, when urban streets did not have sanitary sewers, street gutters were made deep enough to serve that purpose as well; responsibility for operation and maintenance of the dual-purpose street gutter was cooperatively shared between the local government and the inhabitants.

A now obsolete word meaning a street gutter is a kennel.

See also
Road debris
Street sweeper
Pervious concrete

References

Road infrastructure
Danish Railway Museum. The Danish Railway Museum () is the national railway museum of Denmark, located in the city of Odense. Established in 1975, it is situated in a former engine shed adjacent to the city's main railway station. It is the largest railway museum in Scandinavia.

Covering 10,000 square metres, it contains some 50 locomotives and railway carriages on 20 railtracks from all periods of Danish rail history, plus some original buildings of Danish railways. Items from DSB's history include an E class steam locomotive used to haul the funeral train of King Frederik IX of Denmark, a NOHAB diesel locomotive (sectioned on one side, to reveal the engine), an original 1930s Copenhagen-area S-train carriage and a 1950s Lyntog ('lightning train') express diesel multiple unit.

In school holidays, the museum also runs a live steam-hauled train on a short section of track. These usually consist of a Class Hs loco and two carriages.

See also
DSB (railway company)
List of museums in Denmark

References

External links 
 

Museums established in 1975
National railway museums
Railway museums in Denmark
Museums in Odense
MOD West Freugh. MOD West Freugh is located in Wigtownshire,  south east of Stranraer, Dumfries and Galloway, Scotland, and is operated by defence contractor QinetiQ, on behalf of the Ministry of Defence.

It has always been an armaments training school, either for handling or deployment of ordnance.

The site was previously a Royal Air Force station as RAF West Freugh, as well as a Royal Aircraft Establishment as RAE West Freugh.

History
During the First World War the site was a base for naval airships, known as RNAS Luce Bay. The base was provided with one huge airship hangar.

RAF West Freugh opened in 1937 as an armament training camp. During the Second World War, it expanded to include training facilities for observers, navigators, and bomb aimers; and served as a base for the Bombing Trials Unit. The known history of units known at West Freugh is:
22 October 1939 – 10 Service Flying Training School formed. Moved November
4 November 1939 – 4 Air Observer School formed
11 January 1940 – re-designated 4 Bombing & Gunnery School
14 June 1941 – 4 Air Observer School reformed
11 June 1943 – re-designated 4 Observer Advanced Flying Unit
21 June 1945 – 4 Observer Advanced Flying Unit disbanded
April 1957 – RAF West Freugh incident
2001 – Airfield closed, all RAF operations cease
2001 – operations taken over by QinetiQ
In addition to the units listed above (and with manpower possibly drawn from some of them) a Mountain Rescue Team was based at West Freugh from 1945 to 1956. After 1956 the MRT at RAF Leuchars assumed responsibility for the area covered by West Freugh. The team was part of the RAF's Mountain Rescue Service.

The following units were also here at some point:
Squadrons

Units

Satellite Earth Station 
A satellite earth station is located at West Freugh and was established to receive and distribute data from the European Space Agency's ERS radar satellites. In September 2005 it was announced that the earth station at West Freugh was the first outside Canada to be certified to provide imagery from the Canadian RADARSAT commercial satellite.

Present day
In 1987, Exercise Purple Warrior forces utilised West Freugh.

West Freugh, operated by QinetiQ since 2001, is used as a test range for bombs and Air-to-Ground missiles. Its ranges extend over Luce Bay, and an area of land at Torrs Warren.

In 1988 and 1990 its ranges were used to test Phalanx CIWS weapons system with depleted uranium rounds. A subsequent radiological survey of beach, sand and seawater by staff from the Atomic Weapons Establishment concluded that there was no detectable contamination.

The airfield is no longer licensed or active, however it is available for military exercises. West Freugh has also been used on several occasions for exercises by 16 Air Assault Brigade under the Exercise Joint Warrior banner.

See also 
 List of former Royal Air Force stations

References

Citations

Bibliography

External links
MOD West Freugh – LPTA

Airports established in 1936
Bombing ranges
Buildings and structures in Dumfries and Galloway
Royal Air Force stations in Scotland
Royal Air Force stations of World War II in the United Kingdom
Water slope. A water slope () is a type of canal inclined plane built to carry boats from a canal or river at one elevation up or down to a canal or river at another elevation.

History
In 1885, German engineer Julius Greve published drafts for water slopes in German journals. French engineer Jean Aubert advanced the studies in the 1950s and 1960s.

To date, only two water slopes have been built, both in southern France. In 1973 the Montech water slope () was put into service on the Canal latéral à la Garonne.

In 1983 the Fonserannes Water Slope was inaugurated near Béziers on the Canal du Midi. Both water slopes run parallel to existing lock flights. Both water slopes are currently out of service and in disrepair.  However, the slopes and their moving engines can be viewed from a distance.

Operation
The water slope uses a moveable gate in a sloping channel. To ascend the slope the moving gate can be opened to allow a boat to enter the concrete channel. The gate then closes off the bottom of the channel and seals off a wedge of water on which the boat is floating, within the channel. The moveable gate is drawn up the sloping concrete channel pushing the wedge of water before it until reaching the upper water level. When the water level in the wedge is equalised with that of the upper canal, an upper (non-moving) gate is opened and the boat is then allowed to float free.

Descending the water slope is the reverse of the ascent.

See also

 Boat lift

Further reading

References

Canal inclined planes
Abradable coating. An  abradable coating is a coating made of an abradable material – meaning if it rubs against a more abrasive material in motion, the former will be worn whereas the latter will face no wear. Abradable coatings provide a .1 to .2% performance improvement compared to those without coating.

Abradable coatings are used in aircraft jet engines in the compressor and turbine sections where a minimal clearance is needed between the blade tips and the casing.

Abradable coatings have been in use by aero-engine manufacturers in some form or fashion for roughly 50 years

Abradable powder coatings provide an economical and environmentally friendly way to improve the efficiency of engines, compressors and pumps by fine-tuning the operational fit of internal components such as pistons, rotors and cases.  In typical turbo machinery, the clearance between blade tips and the casing must account for thermal and inertial expansion as well as changes in concentricity due to shock loading events. To prevent catastrophic tip to casing contact, conservatively large clearances must be employed.

In small turboprop aircraft, the angle at which abradable coating is applied is impacted by the necessity of the coating process performed at spray angles less than 60 degrees.

The role of abradable coatings is not only to allow for closer clearances, but to automatically adjust clearances, in-situ, to accept physical events and/or thermal scenarios that may be found in a devices operational history.

Manufacturing
Thermal spray: Many techniques are available (Plasma, Flame, etc.).
Sintering: Honeycomb coatings are sintered on the casing
Casting: in the case of polymer coating.

References

Gas turbine technology
Top Secret (aircraft). Top Secret was the name of a Boeing B-29 Superfortress (B-29-36-MO 44–27302, "victor number' 72) modified to carry the atomic bomb in World War II.  It served with the Army Air Forces and United States Air Force from 1945 until 1954.

Airplane history
The plane was assigned to the 393d Bomb Squadron of the 509th Composite Group.  It was one of fifteen Silverplate B-29s used by the 509th. Top Secret was built at the Glenn L. Martin Company aircraft plant at Omaha, Nebraska, as a Block 35 aircraft. It was one of 10 aircraft modified as a Silverplate and designated with Block number 36. The plane was delivered to the Army Air Forces on 2 April 1945.  The 509th assigned it to crew B-8 (1st Lt. Charles F. McKnight, aircraft commander) and it was flown to Wendover Army Air Field, Utah. It left Wendover on 5 June 1945, for North Field, Tinian and arrived 11 June.

It was originally assigned the "victor (unit-assigned identification) number" 2 but on 1 August was given the large 'Square A' tail markings of the 497th Bombardment Group as a security measure and had its "victor number" changed to 72 to avoid misidentification with actual 497th aircraft. It was named Top Secret and its nose art was applied after the atomic bomb missions.

While at Tinian, McKnight and crew B-8 flew Top Secret on 13 practice bombing missions and four combat pumpkin bomb missions against Japanese industrial targets at Otsu, Yokkaichi, Ube, and Toyoda. The plane flew two other pumpkin bomb missions, to Taira (1st Lt. Joseph E. Westover and crew A-4) and Yokkaichi (Capt. Claude Eatherly and crew C-11).

In November 1945 Top Secret returned with the 509th to Roswell Army Air Field, New Mexico. From March to August 1946 it was assigned to the Operation Crossroads task force, then it rejoined the 509th at Roswell. In June 1949 Top Secret was transferred to the 97th Bombardment Group at Biggs Air Force Base, Texas.  It was sent to Tinker Air Force Base, Oklahoma in April 1950 for modification to TB-29 trainer specification by the Oklahoma City Air Materiel Area.

The plane's subsequent assignments were to the 2d Radar Calibration Squadron, Elmendorf Air Force Base in March 1953, and the 5025th Maintenance Group at Elmendorf in August 1953.

In September 1953 it was sent to the 3040th Aircraft Storage Group at Davis-Monthan Air Force Base, Arizona, where it was scrapped in July 1954.

Other aircraft named Top Secret
A General Dynamics FB-111A strategic bomber of the United States Air Force, serial 69–6513, carried the name Top Secret on its nosewheel doors during its service with both the 509th Bombardment Wing at Pease Air Force Base, New Hampshire,  and the 380th Bombardment Wing at Plattsburgh Air Force Base, New York in the 1970s and 1980s.

Sources
 Campbell, Richard H., The Silverplate Bombers: A History and Registry of the Enola Gay and Other B-29s Configured to Carry Atomic Bombs (2005), 

Individual aircraft of World War II
Boeing B-29 Superfortress
Mooring (oceanography). A mooring in oceanography is a collection of devices connected to a wire and anchored on the sea floor. It is the Eulerian way of measuring ocean currents, since a mooring is stationary at a fixed location. In contrast to that, the Lagrangian way measures the motion of an oceanographic drifter, the Lagrangian drifter.

Construction principle
The mooring is held up in the water column with various forms of buoyancy such as glass balls and syntactic foam floats. The attached instrumentation is wide-ranging but often includes CTDs (conductivity, temperature depth sensors), current meters (e.g. acoustic Doppler current profilers or deprecated rotor current meters), and biological sensors to measure various parameters. Long-term moorings can be deployed for durations of two years or more, powered with alkaline or lithium battery packs.

Components

Top buoy

Surface buoys
Moorings often include surface buoys that transmit real time data back to shore. The traditional approach is to use the Argos System. Alternatively, one may use the commercial Iridium satellites which allow higher data rates.

Submerged buoys
In deeper waters, areas covered by sea ice, areas within or near shipping lines or areas that are prone to theft or vandalism, moorings are often submerged with no surface markers. Submerged moorings typically use an acoustic release or a Timed Release that connects the mooring to an anchor weight on the sea floor. The weight is released by sending a coded acoustic command signal and stays on the ground. Deep water anchors are typically made from steel and may be as large as 100 kg. A common deep water anchor consists of a stack of 2–4 railroad wheels. In shallow waters anchors may consist of a concrete block or small portable anchor.

The buoyancy of the floats, i.e. of the top buoy plus additional packs of glass bulbs of foam, is sufficient to carry the instruments back to the surface. In order to avoid entangled ropes, it has been practical to place additional floats directly above each instrument.

Instrument housing

Prawlers
Prawlers (profiling crawlers) are sensor bodies which climb and descend the cable, to observe multiple depths.  The energy to move is "free," harnessed by ratcheting upward via wave energy, then returning downward via gravity.

Depth correction
Similar to a kite in the wind, the mooring line will follow a so-called (half-)catenary.
The influence of currents (and wind if the top buoy is above the sea surface) can be modeled and the shape of the mooring line can be determined by software.  If the currents are strong (above 0.1 m/s) and the mooring lines are long (more than 1 km), the instrument position may vary up to 50 m.

See also
 Benthic lander, a mooring which does not have any mooring line

References 

Oceanography
Physical oceanography
Oceanographic instrumentation
Ocean currents
Biological oceanography

de:Boje (Schifffahrt)