omniomni/omni-engineering huggingface dataset:
Cameron D-96. The Cameron D-96 was the first hot air airship, a powered, steerable lighter-than-air craft carrying two or three crew marrying the elongated envelope of an airship with the externally localized heat source of a modern hot air balloon. It was designed and built in the UK and first flown in 1973.

Design and development
Cameron Balloons had been producing hot air balloons for five years when they designed the world's first hot air airship or thermal airship. This, the D-96, has much in common with the balloons, being a non-rigid airship, covered in a nylon fabric and with a propane burner to feed hot air into the envelope from a gondola suspended below it. However, it has the elongated body shape of conventional helium and hydrogen filled airships, airscrew propulsion and stabilizing tailfins. With a length to maximum diameter ratio of only about 2.5, the envelope is fatter than that of many airships. The D-96 is powered a 1.6 L Volkswagen engine, modified to run on propane so that engine and burner use the same fuel. Mounted at the rear of the gondola, this drives a large diameter, partly shrouded propeller. This gondola carries propane fuel and a double burner, the pilot and up to two passengers. Hot air is guided into the envelope by a small, funnel-like extension above the burners.

On 4 January 1973 Don Cameron and Teddy Hall demonstrated the first D-96, registration G-BAMK, at the Icicle meeting at Newbury, Berkshire. Some records state that this first flight was made on 7 January or over the weekend of 6–7 January. After some initial testing, Cameron's attention returned to balloon manufacture but interest in the airship was revived in 1976 by an order from the U.S.A. The early flights had revealed some directional stability problems, addressed by progressively increasing the number of tailfins. The instabilities were finally cured by a four-finned, cruciform arrangement, with the fins inflated by air from the propeller slipstream, fed from an intake with a tongue-like scoop through a passage along the keel. A rudder, operated from the gondola by cable, was added to the lower fin. At the same time the gondola suspension was improved so that it no longer distorted the envelope.

Originally the D-96 had an envelope capacity of 96,000 cu ft (2,718 m³), as indicated by its name, but during 1978 the envelope was lengthened, increasing the volume by about 7%. This new envelope was used on subsequent production D-96s.

Operational history
16 D-96s had been built by January 1984 for customers across Europe, in Australia, Canada, U.S.A and Japan; of these, eight appeared on the UK civil aircraft register, though they are all deregistered in 2012. One of these is now on the 2010 French register; another D-96, not previously on the UK register is registered in Spain.

Specifications (1984 version)

References

External links
Cameron D-96 image

Airships
Balloons (aeronautics)
Wickham B. The Wickham B is an American experimental twin engined, homebuilt aircraft.

Design and development
The twin engine aircraft was designed by Boeing engineer Jim Wickham in order to fly safely on one engine over the Seattle area.

The model B is a high-wing, fixed tricycle landing gear, twin engine aircraft. The aircraft uses all aluminum construction with fiberglass cowlings, nose cone and wheel pants. The wings are configured with Fowler flaps.  The wing has no dihedral.  The two  fuel tanks are located in the leading edges of the outboard panels just outboard of the engines. The fuel tanks are independent of each other with no cross feed capability or fuel lines in the cabin. The aircraft uses a throw-over yoke control, similar to a Beechcraft Bonanza. Design of the aircraft was started in December, 1957 and first flew in April, 1968.  Initially the engines were 125 hp Lycoming O-290's but were subsequently changed to 150 hp Lycoming O-320 engines.

Operational history
The Wickham B was donated to the Seattle Museum of Flight, then traded to the South Seattle Community College. In 2002, the aircraft was sold and restored to flying condition by Ross Mahon in Everett, Washington. In 2012 the plane was sold to Curtis Clark and it is based at Deer Valley Airport in Phoenix, Arizona.

Specifications (Model B)

See also

References

Homebuilt aircraft
High-wing aircraft
1960s United States sport aircraft
Twin piston-engined tractor aircraft
Bokaro Institute of Technology. Bokaro Institute of Technology is a private Engineering college located in Bokaro Steel City, Jharkhand. The college was established in 1982–83 and it is affiliated to Vinoba Bhave University. The college was opened by Chas-Bokaro Vikas Samiti, a well known social organization of Bokaro.

References 

Education in Bokaro Steel City
Educational institutions established in 1982
Engineering colleges in Jharkhand
1982 establishments in Bihar
Sustained load cracking. Sustained load cracking, or SLC, is a metallurgical phenomenon that occasionally develops in pressure vessels and structural components under stress for sustained periods of time.

It is particularly noted in aluminium pressure vessels such as diving cylinders.

Sustained load cracking is not a manufacturing defect; it is a phenomenon associated with certain alloys and service conditions:
6351 aluminum alloy
Overstressing due to excessive filling pressure
Abuse and mechanical damage

Occurrence

Crack growth is reported to be very slow by Luxfer, a major manufacturer of aluminium high-pressure cylinders. Cracks are reported to develop over periods in the order of 8 or more years before reaching a stage where the cylinder is likely to leak, which allows timely detection by properly trained inspectors using eddy-current crack-detection equipment.

SLC cracks have been detected in cylinders produced by several manufacturers, including Luxfer, Walter Kidde, and CIG gas cylinders.

Most of the cracking has been observed in the neck and shoulder areas of cylinders, though some cracks in the cylindrical part have also been reported.

History
The phenomenon was first noticed in 1983 in hoop-wound fibre-reinforced aluminium alloy cylinders, which burst in use in the USA. The alloy was 6351 with a relatively high lead content (400 ppm), but even after the lead content was lowered, the problem recurred, and subsequently the problem was detected in monolithic aluminium cylinders. The first incidence of an SLC crack in the cylindrical part of a cylinder was reported in 1999.

Detection
Neck cracks are readily observed during inspection, but body and shoulder cracks are more difficult to detect. Neck thread cracks can be non-destructively tested using eddy-current crack-detection equipment. This is reported to be reliable for alloy 6351, but false positives have been reported for tests on alloy 6061.

Contributing factors
All of these forms of crack development are the result of the cylinder being subject to high pressure for prolonged periods. The cracks are intergranular and occur at grain boundaries. There is no evidence of stress corrosion or fatigue.

The presence of a relatively high lead content has been identified as a contributory factor. Cracking at the grain boundaries is accelerated in the presence of lead. The presence of bismuth is also suspected to be contributory.

Alloy composition has also been found to be a factor. Alloy 6061 has shown good resistance to SLC, as have alloys 5283 and 7060. 
Manufacturing defects such as folds on the inside surface have been shown to be harmful, particularly for parallel-threaded cylinders.
Grain size has been shown to be of relatively minor importance.

Alloy composition

See also

References

Diving equipment failure modes
Metallurgy
LCVP (United Kingdom). The Landing Craft Vehicle Personnel (LCVP) is a versatile amphibious landing craft designed to transport troops or armoured vehicles from ship to shore during amphibious landings. The designation was first used in British service for the LCVP Mk2s introduced with the two Fearless class amphibious transport docks, the role having previously been carried out by the Landing Craft Assault developed during the Second World War. They are manned and operated by 1 Assault Group Royal Marines.

LCVP Mk2
The LCVP Mk2 was built by the Dorset Yacht Company at Poole during the 1960s. The craft was powered by two Foden diesel engines and could carry 35 fully equipped Royal Marines Commandos or two Land Rovers. Foxtrot 7, one of four carried by HMS Fearless (L10), rescued 41 crew members from the burning HMS Antelope (F170) on 24 May 1982 during the Falklands War. It is preserved ashore at the Royal Marines Museum, Portsmouth. Foxtrot 8 is located in Boathouse 4 of the Portsmouth Historic Dockyard who in November 2015 were awarded funding to restore her back to sea-going condition. Tango 5, one of HMS Intrepid's LCVPs, is currently the "Gate Guardian" at RM Chivenor.

The LCVP Mk2 is no longer in service.

LCVP Mk4
The LCVP Mk4 came into service in 1986 replacing the older LCVP Mk2. Throughout their service they were mostly used in independent Royal Marine amphibious formations. They had a draught of 75 cm at the stern and were powered by twin Perkins 6 cylinder turbo diesel engines Four were used by the British Army's Royal Logistic Corps.

As of 2012, the LCVP Mk4 has been withdrawn from service.

LCVP Mk5
The LCVP Mk5 was built by Vosper Thornycroft and FBM Babcock Marine, with the first entering service in 1996. They represent a significant improvement in capability over the preceding Mk4s. Four Mk5s together can transport a full Royal Marine company (around 140 troops). Presently, the Mk5s operate from the amphibious warfare ships HMS Albion (L14) and HMS Bulwark (L15).

In 2012, a total of 23 Mk5s were in service with pennants 9473, 9673 to 9676 and 9707 to 9724. By 2014 LCVPs 9473, 9673, 9674 and 9708 had been withdrawn from service. In 2023 it was reported that 8 Mk5Bs remained in service.

In 2023 it was reported that the Royal Navy and Marines were seeking a replacement for the LCVP Mk 5 with the objective of securing service entry by 2027. The new Commando Insertion Craft were to have a low signature and be able to carry a strike team and small vehicle over a distance of 150 miles at a speed of 25 knots. A production contract was reportedly envisaged by 2025.

Specifications
The LCVP Mk5 has the following specifications:
Weight (full): 24,000 kg (24 tonnes)
Length: 
Width : 
Speed (full): 
Endurance: In excess of 
Troops: 38 Royal Marines (3 crew, 35 fully equipped troops)
Cost: £1,000,000

See also
List of active Royal Marines military watercraft

References

External links
Royal Marines - Landing Craft (royalnavy.mod.uk)

Ship types
Royal Marines
Landing craft
Quasi-harmonic approximation. The quasi-harmonic approximation is a phonon-based model of solid-state physics used to describe volume-dependent thermal effects, such as the thermal expansion. It is based on the assumption that the harmonic approximation holds for every value of the lattice constant, which is to be viewed as an adjustable parameter.

Overview 
The quasi-harmonic approximation expands upon the harmonic phonon model of lattice dynamics. The harmonic phonon model states that all interatomic forces are purely harmonic, but such a model is inadequate to explain thermal expansion, as the equilibrium distance between atoms in such a model is independent of temperature.

Thus in the quasi-harmonic model, from a phonon point of view, phonon frequencies become volume-dependent in the quasi-harmonic approximation, such that for each volume, the harmonic approximation holds.

Thermodynamics 
For a lattice, the Helmholtz free energy F in the quasi-harmonic approximation is

where Elat is the static internal lattice energy, Uvib is the internal vibrational energy of the lattice, or the energy of the phonon system, T is the absolute temperature, V is the volume and S is the entropy due to the vibrational degrees of freedom.
The vibrational energy equals

where N is the number of terms in the sum,  is introduced as the characteristic temperature for a phonon with wave vector k in the i-th band at volume V and  is shorthand for the number of (k,i)-phonons at temperature T and volume V. As is conventional,  is the reduced Planck constant and kB is the Boltzmann constant. The first term in Uvib is the zero-point energy of the phonon system and contributes to the thermal expansion as a zero-point thermal pressure.

The Helmholtz free energy F is given by

and the entropy term equals

,

from which F = U - TS is easily verified.

The frequency ω as a function of k is the dispersion relation.  Note that for a constant value of V, these equations corresponds to that of the harmonic approximation.

By applying a Legendre transformation, it is possible to obtain the Gibbs free energy G of the system as a function of temperature and pressure.

Where P is the pressure. The minimal value for G is found at the equilibrium volume for a given T and P.

Derivable quantities 

Once the Gibbs free energy is known, many thermodynamic quantities can be determined as first- or second-order derivatives. Below are a few which cannot be determined through the harmonic approximation alone.

Equilibrium volume 
V(P,T) is determined as a function of pressure and temperature by minimizing the Gibbs free energy.

Thermal expansion 
The volumetric thermal expansion αV can be derived from V(P,T) as

Grüneisen parameter 
The Grüneisen parameter γ is defined for every phonon mode as

where i indicates a phonon mode. The total Grüneisen parameter is the sum of all γis. It is a measure of the anharmonicity of the system and closely related to the thermal expansion.

References 

 Dove, Martin T. (1993). Introduction to lattice dynamics, Cambridge university press. .

Condensed matter physics
Lattice models
Catskill-Delaware Water Ultraviolet Disinfection Facility. The Catskill-Delaware Water Ultraviolet Disinfection Facility is a  ultraviolet (UV) water disinfection plant built in Westchester County, New York to disinfect water for the New York City water supply system. The compound is the largest ultraviolet germicidal irradiation plant in the world.

The UV facility treats water delivered by two of the city's aqueduct systems, the Catskill Aqueduct and the Delaware Aqueduct, via the Kensico Reservoir. (The city's third supply system, the New Croton Aqueduct, has a separate treatment plant.)

The plant has 56 energy-efficient UV reactors, and cost the city $1.6 billion. Mayor Michael Bloomberg created research groups between 2004-2006 to decide the best and most cost-effective ways to modernize the city's water filtration process, as a secondary stage following the existing chlorination and fluoridation facilities. The UV technology effectively controls microorganisms such as giardia and cryptosporidium which are resistant to chlorine treatment. The city staff determined that the cheapest alternatives to a UV system would cost over $3 billion. In response to this finding, Bloomberg decided to set up a public competitive contract auction. Ontario based Trojan Technologies won the contract.

The facility treats  of water per day. The new facility was originally set to be in operation by the end of 2012. The facility opened on October 8, 2013.

References 

Environment of New York (state)
Environment of New York City
Water treatment facilities
Ultraviolet radiation
2013 establishments in New York (state)
Water infrastructure of New York City
SAB C-100 Vulcan. The SAB C-100 Vulcan (or C 100) is an Italian ultralight and light-sport aircraft produced by SAB Aviation of Benevento. The aircraft is supplied as a kit for amateur construction or as a complete ready-to-fly-aircraft.

Design and development
SAB Aviation purchased Corivi Aviation and their design, the Corivi Pegaso, and the Pegaso was further refined into the C-100 Vulcan.

The Vulcan was designed to comply with the Fédération Aéronautique Internationale microlight rules and US light-sport aircraft rules. It features a cantilever low wing, a two-seats-in-side-by-side configuration enclosed cockpit under a bubble canopy, fixed or optionally retractable tricycle landing gear and a single engine in tractor configuration.

The aircraft is made from sheet aluminum. Its  span wing has an area of  and mounts flaps. The standard engine available is the  Rotax 912ULS four-stroke powerplant.

The retractable gear version, with its pneumatic retraction mechanism, is intended for the European microlight market, whereas the fixed gear model is sold in the United States in the LSA category. The LSA version was first shown at Sun 'n Fun in 2010.

The design has been accepted by the Federal Aviation Administration as a special light-sport aircraft.

Specifications (C-100 Vulcan)

References

External links

2000s Italian ultralight aircraft
Homebuilt aircraft
Light-sport aircraft
Single-engined tractor aircraft
Low-wing aircraft
Soil value. Soil value () or BWZ is a comparative assessment of soil quality used in Germany. It is determined from soil sampling data and ranges from 0 (very low) to 100 (very high).

According to the Geological Service of the state of North Rhine-Westphalia, the soil value of arable land is based on a field assessment framework which combines an assessment of soil type, soil condition (soil development) and the parent material of which the soil is composed. The result, the soil value, expresses the relative net income that, under normal and proper management, is determined only by the profitability of the soil. Additions or deductions in this value to take account of variations in yield due to terrain and climate (e.g. average annual temperature) give the field value (Ackerzahl).

Range of values 
The following colour scheme is used referring to the soil quality for certain ranges of values: 

The values exhibited by different types of soil are:

Origins 
As a yardstick for soil quality, a "Reich Standard Farm" was set up during the Third Reich in the parish of Eickendorf in the Magdeburger Börde, an exceptionally rich arable region. During the Reich Soil Assessment (Reichsbodenschätzung) following the Soil Assessment Act in 1934 a soil value of 100 was established in the leading Reich farm of Haberhauffe/Jäger. It was the basis of comparison for the tax rating of farms in Germany. Since this farm was no longer available for comparisons within West Germany after the Second World War, a farm in Machtsum near Harsum in the Hildesheim Börde was designated as the Federal Standard Farm. During later measurements, an even higher value of BWZ – 102.8 – was measured in Mölme, about 20 km east of Hildesheim within the municipality of Söhlde. It is the highest value ever recorded in Germany.

Another measure, the field value (Ackerzahl), is derived from the soil value, taking account of other factors such as climate and location e.g. along the edge of woodland.

See also 
 Soil classification
 Soil quality
 Soil science
 Soil Use Efficiency
 Crop yield

References

External links 
 Wertzahlen der Bodenschätzung  at www.gd.nrw.de. Accessed on 2 Sep 2012.
 Eickendorf

Soil science
Pedology
Agronomy
Lapsed listener problem. In computer programming, the lapsed listener problem is a common source of memory leaks for object-oriented programming languages, among the most common ones for garbage collected languages.

It originates in the observer pattern, where observers (or listeners) register with a subject (or publisher) to receive events. In basic implementation, this requires both explicit registration and explicit deregistration, as in the dispose pattern, because the subject holds strong references to the observers, keeping them alive. The leak happens when an observer fails to unsubscribe from the subject when it no longer needs to listen. Consequently, the subject still holds a reference to the observer which prevents it from being garbage collected — including all other objects it is referring to — for as long as the subject is alive, which could be until the end of the application.

This causes not only a memory leak, but also a performance degradation with an "uninterested" observer receiving and acting on unwanted events. This can be prevented by the subject holding weak references to the observers, allowing them to be garbage collected as normal without needing to be unregistered.

References

Software bugs
Software anomalies
Ron Sharpe (businessman). 

Life and career
Sharpe was a joint managing director of Industrial Holdings Pty Ltd. He was a former Chairman of the NSW Branch of the Order of Australia Association. Sharpe was a carpenter, a licensed commercial builder, a licensed mechanic and built a career in the field of civil engineering. Throughout his life he was involved in civil infrastructure and road maintenance through the Sharpe family business. Ron Sharpe was the Founding Chairman of the Road Profiling Association of Australia, which evolved to become a part of the Australian Asphalt Pavement Association. As part of the celebration of AAPA's 40th anniversary in 2009, he was recognised for his services to the industry.

In November 2009, a book by Margaret Hardy titled Significant Men of the Central Coast was launched and included Ron Sharpe and his sons; who were mentioned for their involvement in providing support to community groups through donations, partnerships, volunteering and community sponsorships.

Sharpe was a member of the Umina Apex Club and was awarded Life Membership in 1990. He helped raise funds for a number of causes including the Surf Rescue Helicopter and the Royal Volunteer Coastal Patrol. He was involved with the Salvation Army throughout his life, being a member of the Salvation Army Band, building the Salvation Army Hall at Umina with his father and being chairperson for the Peninsula Red Shield Appeal.

Ron Sharpe was a chairman and regional coordinator of the New South Wales State Committee of the Order of Australia Association.

Honours
In January 2005, Sharpe was named Citizen of the Year for the City of Gosford and on Australia Day 2006, he was awarded an Order of Australia (OAM) in recognition of his service to the community of the Gosford region through a range of service and social welfare organisations.

Letter of condolence from the governor-general of Australia
Upon Sharpe's death, David Hurly, the Governor-General of Australia, released a letter of condolence.

References

1950 births
Australian businesspeople
Living people
Developer! Developer! Developer!. Developer! Developer! Developer!, more commonly known as DDD, is a series of community conferences aimed at software developers.

History 
DDD conferences started in 2005, as a community conference organised by software developers for software developers. The first was held at Microsoft's TVP campus in Reading, United Kingdom. There have been 10 DDD conference held in this location, as well as a number of regional conferences held in Belfast, Bristol, Wales, Cambridge, Dublin, Dundee, Edinburgh, Galway, Glasgow, Leeds, Sunderland, Taunton and Bradford. In Australia: Perth, Sydney, Melbourne, Brisbane and Adelaide. In South Korea: Seoul.

The original DDD event in Reading has frequently sold out on the day the tickets become available. The record is 350 tickets selling out in 13 minutes.

Key Values 
DDD was set up with a number of key elements in mind.

 It is free
 It is on a Saturday
 An open submissions process
 A democratically chosen agenda

The Australian DDD events do have a nominal ticket price, primarily to minimise the number of people who register to attend but don't show up. Subsidised tickets are available for those who can't afford this.

References

External links 
 Main DDD Website
 DDD North Website
 DDD SouthWest Website
 DDD East Anglia Website
 DDD Scotland Website
 DDD Brisbane Website
 DDD Melbourne Website
 DDD Perth Website
 DDD Sydney Website
 DDD Wales 
 DDD East Midlands (first event scheduled for 2019)
 DDD Brisbane Website
 DDD Adelaide Website
 DDD Seoul Website

Software developer communities
Computer conferences
Microsoft conferences