omniomni/omni-engineering huggingface dataset:
Apache Druid. Druid is a column-oriented, open-source, distributed data store written in Java. Druid is designed to quickly ingest massive quantities of event data, and provide low-latency queries on top of the data. The name Druid comes from the shapeshifting Druid class in many role-playing games, to reflect that the architecture of the system can shift to solve different types of data problems.

Druid is commonly used in business intelligence-OLAP applications to analyze high volumes of real-time and historical data. Druid is used in production by technology companies such as Alibaba, Airbnb, Nielsen, Cisco, eBay, Lyft, Netflix, PayPal, Pinterest, Reddit, Twitter, Walmart, Wikimedia Foundation and Yahoo.

History 
Druid was started in 2011 by Eric Tschetter, Fangjin Yang, Gian Merlino and Vadim Ogievetsky to power the analytics product of Metamarkets. The project was open-sourced under the GPL license in October 2012, and moved to an Apache License in February 2015.

Architecture 

Fully deployed, Druid runs as a cluster of specialized processes (called nodes in Druid) to support a fault-tolerant architecture where data is stored redundantly, and there is no single point of failure. The cluster includes external dependencies for coordination (Apache ZooKeeper), metadata storage (e.g. MySQL, PostgreSQL, or Derby), and a deep storage facility (e.g. HDFS, or Amazon S3) for permanent data backup.

Query management 
Client queries first hit broker nodes, which forward them to the appropriate data nodes (either historical or real-time). Since Druid segments may be partitioned, an incoming query can require data from multiple segments and partitions (or shards) stored on different nodes in the cluster. Brokers are able to learn which nodes have the required data, and also merge partial results before returning the aggregated result.

Cluster management 
Operations relating to data management in historical nodes are overseen by coordinator nodes. Apache ZooKeeper is used to register all nodes, manage certain aspects of internode communications, and provide for leader elections.

Features 
 Low latency (streaming) data ingestion.
 Arbitrary slice and dice data exploration.
 Sub-second analytic queries.
 Approximate and exact computations.

Performance 
In 2019, researchers compared the performance of Hive, Presto, and Druid using a denormalized Star Schema Benchmark based on the TPC-H standard. Druid was tested using both a “Druid Best” configuration using tables with hashed partitions and a “Druid Suboptimal” configuration which does not use hashed partitions.

Tests were conducted by running the 13 TPC-H queries using TPC-H Scale Factor 30 (a 30GB database), Scale Factor 100 (a 100GB database), and Scale Factor 300 (a 300GB database).

Druid performance was measured as at least 98% faster than Hive and at least 90% faster than Presto in each scenario, even when using the Druid Suboptimized configuration.

See also 

 List of column-oriented DBMSes

References

External links 
 

Druid
Distributed data stores
Structured storage
NoSQL
Free database management systems
Oxygenated treatment. Oxygenated treatment (OT) is a technique used to reduce corrosion in a boiler and its associated feedwater system in flow-through boilers.

Process
With oxygenated treatment, oxygen is injected into the feedwater to keep the oxygen level between 30 and 50 ppb. OT programs are most commonly used in supercritical (i.e. >3250psi) power boilers. The ability to change an existing sub-critical boiler over to an OT program is very limited. "Common injection points are just after the condensate polisher and again at the deaerator outlet." This forms a thicker protective layer of hematite (Fe2O3) on top of the magnetite. This is a denser, flatter film (vs. the undulation scale with OT) so that there is less resistance to water flow compared to AVT.  Also, OT reduces the risk of flow-accelerated corrosion.

When OT is used, conductivity after cation exchange (CACE) at the economiser inlet must be maintained  below 0.15μS/cm  this can be achieved by the use of a full-flow condensate polisher.

Comparison of AVT to OT

See also
 Heat recovery steam generator
 Flow-accelerated corrosion
 Oxygen scavenger

References

External links
Lamella Clarifier

Water treatment
Weeks Hardware. Weeks Hardware is a historic two-story brick 1913 hardware store building in Brooksville, Florida, located at 115 North Main.

The store was called Miro Hardware through the end of World War II, as a combination of the first names of Rosie and Mammie Weeks.

As of 2003, the store was the "oldest active business in town," according to the St. Petersburg Times, which added:
The reluctance to modernize is evident everywhere. The ceiling is high, made of elaborately patterned tin and in need of paint. The freight elevator in the back of the store is powered by hand.

A tall, darkly stained plywood case that holds bolts and screws in its dozens of drawers, was built, according to a little brass label on one corner, by A.R. Brown on May 7, 1901.

The founder's grandson, Joseph C. Weeks, worked in the store since childhood, and took over the business after returning from naval service and graduating from the University of Florida. Mr. Weeks, aged 82, was honored by the Brooksville City Council as "the 2009 Great Brooksvillian."

The building was owned by John Weeks, the first President of the First Federal Bank.

The historic J.M. Rogers Department Store built in 1912 is located across the street at 120 North Main.

Weeks House

The Weeks House is a historic home at 118 South Brooksville Avenue. It was built circa 1900 and was the original home of the founder of Weeks Hardware.

Old Weeks House

The Old Weeks House is a historic residence at 122 West Fort Dade. It was built by sawmill owner G. Gordy in 1882 using heart of pine. The Weeks family owned the house from the 1930s until the 1970s. It belonged to Joe Weeks' uncle and his cousin. It is reputed to be haunted.

References

Buildings and structures in Brooksville, Florida
Commercial buildings completed in 1913
1913 establishments in Florida
Reflex Lightning Bug. The Reflex Lightning Bug, also called the Jones Lightning Bug, is an American homebuilt aircraft that was designed by Nick Jones and produced by Reflex Fiberglass Works of Walterboro, South Carolina, introduced in the mid-1990s. When it was available the aircraft was supplied as a kit for amateur construction.

Design and development
The Lightning Bug features a cantilever low-wing, a single-seat enclosed cockpit under a bubble canopy, fixed tricycle landing gear with wheel pants, a retractable nose wheel and a single engine in tractor configuration.

The aircraft is made from a combination of stainless steel and fiberglass. Its  span wing has a wing area of . The cabin width is . The standard engine used is the  AMW 808 in-line three cylinder, liquid-cooled, two-stroke, dual ignition, aircraft engine. With that engine the aircraft can cruise at .

The Lightning Bug has a typical empty weight of  and a gross weight of , giving a useful load of . With full fuel of  the payload for the pilot and baggage is . The aircraft meets American FAR 23 aerobatic category requirements at a gross weight of .

The standard day, sea level, no wind, take off with a  engine is  and the landing roll is , due to its  stall speed.

The manufacturer estimated the construction time from the supplied kit as 300 hours.

Operational history
In February 2014 two examples were registered in the United States with the Federal Aviation Administration, although a total of nine had been registered at one time.

Specifications (Lightning Bug)

See also
List of aerobatic aircraft

References

External links
Photo of a Lightning Bug

Lightning Bug
1990s United States sport aircraft
1990s United States civil utility aircraft
Single-engined tractor aircraft
Low-wing aircraft
Homebuilt aircraft
Aerobatic aircraft
Montreal Aviation Museum. The Montreal Aviation Museum (), formerly the Canadian Aviation Heritage Centre (), is an aviation museum located in Sainte-Anne-de-Bellevue, Quebec, Canada.

History
The Canadian Aviation Heritage Centre was established in 1998 by Godfrey Pasmore.  The museum opened to the public in 2009. The Canadian Aviation Heritage Centre changed its name to the Montreal Aviation Museum in 2016.

Collection
The museum collection includes the following aircraft:

Blériot XI
Fairchild Bolingbroke Mk IV
Fairchild FC-2
Fleet Canuck
Curtiss-Reid Rambler

Projects under restoration
Fairchild Bolingbroke Mk IV
Noorduyn Norseman
Canadair CF-104 Starfighter

See also
List of aviation museums

References

External links

Official website

Aerospace museums in Quebec
Museums in Montreal
Sainte-Anne-de-Bellevue, Quebec
Museums established in 1998
1998 establishments in Quebec
I-4K. I-4K is a satellite bus being developed by Indian Space Research Organisation (ISRO). It will be a standard bus for  class communication satellites; the I in I-4K stands for INSAT, a group of communication satellites developed and launched by ISRO. The I-4K spacecraft bus can supply DC power of 10 to 15 kilowatts.

List of satellites being developed with I-4K bus
 GSAT series

See also

 Comparison of satellite buses

References 

Indian Space Research Organisation
Satellite buses
Requirement diagram. A requirement diagram is a diagram specially used in SysML in which requirements and the relations between them and their relationship to other model elements are shown as discussed in the following paragraphs.

Derive requirement relationship 

If a requirement is derived from another requirement, their relation is named "derive requirement relationship".

Namespace containment 

If a requirement is contained in another requirement, their relation is named "namespace containment".

Satisfy relationship 

If a requirement is satisfied by a design element, their relation is named "satisfy relationship".

Copy relationship 

If a requirement is a copy of another requirement, their relation is named "copy relationship".

Verify relationship 

If there exists a relation between a requirement and a test case verifying this requirement, their relation is named "verify relationship".

Test case 

A test case is defined by a flow checking whether the system under consideration satisfies a requirement.

Refine relationship 

If a requirement is refined by other requirements / model elements, the relation is named "refine relationship".

Trace relationship 

If there exists a relation between a requirement and an arbitrary model element traced by this requirement, their relation is named "trace relationship".

References 

Systems Modeling Language
Software requirements
Systems engineering
Diarylide pigment. Diarylide pigments are organic compounds that are used as pigments in inks and related materials.  They often are yellow or yellow-green.  To some extent, these organic compounds have displaced cadmium sulfide from the market.  Being pigments, these compounds exist as (yellow) powders of low solubility in water.  They are similar to the simpler monoazo pigments called arylide yellows.

Production and properties

The formation of diarylide pigments involves the reaction of doubly diazotized aromatic diamines (derivatives of benzidine) with acetoacetanilide.  By varying both of these components, several useful pigments have been produced. A related family of organic pigments are the simpler arylides, which arise from the coupling of mono-diazonium salts with the same coupling partners.

The pigments' colors can range from yellow to yellow-green.  One common diarylide yellow pigment is Pigment yellow 12.  From the selection of diarylide yellow pigments shown below one can appreciate the subtle changes in the substituents.  Worldwide production of organic pigments was estimated to be about 250,000 metric tons (t) in 2006, with about 25%, or 62,500 t, being diarylide yellows.

Being pigments, these compounds have very low solubility, especially in water.  Single crystals for X-ray crystallography can however be grown from hot solutions in organic solvents.  For example, crystals of Pigment Yellow 13, 14, and 63 were grown by slow cooling 200 °C solutions of the pigments in 1,2,4-trichlorobenzene.  These vigorous conditions also indicate the considerable thermal stability enjoyed by these compounds.  X-ray crystallography, spectroscopy]], and electronic structure calculations consistently show that these compounds exist as the (bis) keto-hydrazone tautomers, even though these structures are often depicted as diazo compounds.

Uses 
The diarylide yellows are the most common yellow pigments used in printing as well as a wide variety of other applications.  Due to their stability, diarylide yellows are used in inks, coatings, and as plastic colorants.  The pigment is insoluble. It is a standard pigment used in printing ink and packaging industry.  The diarylide yellow pigment Yellow 12 is one of the three main colored pigments used in the four color process of color printing.  As such, its use is ubiquitous in printing both in commercial applications and in home color printers, as well as in textile printing.

Toxicity and hazards 
Diarylide yellow pigments are considered to be non-toxic. There is, however, evidence that these pigments degrade when exposed to temperatures above 200 °C to release 3,3'-dichlorobenzidine, a carcinogen that is listed in the U.S. EPA's Toxics Release Inventory.  3,3’-Dichlorobenzidine is structurally similar to one of the polychlorinated biphenyl congeners, PCB 11 (3,3’-dichlorobiphenyl), and some evidence indicates that the use of diarylide yellow pigments introduces PCB 11 to the environment.

See also 
 List of colours

References 

Pigments
Organic pigments
Shades of yellow
DFS Sperber Senior. The DFS Sperber Senior () was a competition sailplane designed and built in Germany in 1936. During 1937 the sole example visited the United States and scored highest in the US National Soaring Competition.

Design and development

Although nominally a development of his earlier DFS Rhönsperber, Hans Jacobs' Sperber Senior was a completely new design intended to improve on the performance of its predecessor and to accommodate larger pilots.  It was a shoulder wing aircraft with a double straight tapered gull wing, built around two spars and fabric covered apart from the leading edge from the front spar forward and the wing roots, which were plywood skinned. The wing roots were carefully faired into the fuselage.  The inner panels, filling about one third of the span had only slight taper, the sweep entirely on the trailing edge, and about 10° of dihedral.  Outboard the taper was much stronger, with a taper ratio of 0.45. Here the leading edge was slightly swept but there was no dihedral.  Ailerons occupied the whole of the outer panels' trailing edges.

The Senior had a completely ply covered fuselage with a narrow ovoid cross section which was deep in the cockpit area but tapered progressively to the tail.  The cockpit was just ahead of the wing, covered by a multipart glazing which, attached to a small area of the upper forward fuselage, hinged to the right for access.  The rear of the canopy was above the fuselage line and a long, ply covered fairing reaching well behind the wing blended it in. A tapered, round tipped and largely fabric covered horizontal tail was mounted on top of the fuselage, far enough forward to place the trailing edges of its elevators at the rudder hinge line.  The latter was mounted on a narrow ply covered fin, carefully faired into the fuselage and extending below it to form a tail bumper.  The mostly fabric covered rudder was full, curved and slightly pointed, likewise extending below the fuselage.  A short skid from just behind the nose to beyond mid-chord completed the landing gear.

Operational history

The Sperber Senior first flew in 1936 and took part in the Rhön German National championships of that year but its pilot, Ludwig Hofmann retired for personal reasons midway through.  In 1937 Peter Riedel took it to the US to participate in the 8th American National Competitions at Elmira. He finished with the highest score but, not being a US citizen was denied the title of champion.  Whilst in the US he made a seven-hour flight over central New York. After he returned to Germany the Sperber Senior was retired.

Specifications

References

1930s German sailplanes
DFS aircraft
Glider aircraft
Shoulder-wing aircraft
Aircraft first flown in 1936
Gull-wing aircraft
Shore-based test facility. A shore-based test facility (SBTF), also known as a land-based test facility, is used for the flight testing of aircraft that operate from aircraft carriers. They are also used for the training of the pilots who will operate the aircraft from the aircraft carriers. Only four countries in the world have SBTF or LBTF; they are China, India, Ukraine / Russia and the United States.

China
China's People's Liberation Army Navy has two test centers, one at Wuhan and one at Huludao.

India

The Indian Navy's SBTF is located at INS Hansa in Goa, and is used to train and certify navy pilots of the Mikoyan MiG-29K for the aircraft carrier INS Vikramaditya, and for the developmental trials of the naval HAL Tejas. This SBTF was designed by Nevskoye Design Bureau (NDB) of Russia for Aeronautical Development Agency (ADA). The ski-jump resembles part of a parabola and has an inclination of 14 degrees. The highest point of the ski-jump is at 5.71 metres from the ground.

Ukraine
The Ukrainian Navy inherited a former Soviet Naval Aviation base at Novofedorivka. This base now hosts the Nitka Naval Pilot Training Center, which is used by the Russian Navy to train their carrier pilots. This base, being in Crimea, is now in Russian control.

United States

The United States Navy has been testing the new Electromagnetic Aircraft Launch System from the land based launch facility at Joint Base McGuire-Dix-Lakehurst.

References

Naval aviation services
Indian Navy
People's Liberation Army Navy
Ukraine Navy facilities
United States Navy
Intelsat II F-2. Intelsat II F-2, also known as Lani Bird, was a communications satellite operated by Intelsat. Launched in 1967, it was operated in geostationary orbit at a longitude of 174 degrees east until 1969.

The second of four Intelsat II satellites to be launched, Intelsat II F-2 was built by Hughes Aircraft around the HS-303A satellite bus. It carried two transponders, which were powered by body-mounted solar cells generating 85 watts of power. The spacecraft had a mass of  at launch, decreasing to  by the beginning of its operational life.

Intelsat II F-2 was launched atop a Delta E1 rocket flying from Launch Complex 17B at the Cape Canaveral Air Force Station. The launch took place at 10:55:00 on January 11, 1967, with the spacecraft entering a geosynchronous transfer orbit. It fired an SVM-1 apogee motor to place itself into its operational geostationary orbit, arriving on-station at 174° East on February 4, 1967. The satellite achieved around two years of operation at that slot before failing in 1969.

As of February 4, 2014, Intelsat II F-2 was in an orbit with a perigee of , an apogee of , inclination of 6.80 degrees and an orbital period of 23.93 hours.

References

Intelsat satellites
Hughes aircraft
Spacecraft launched in 1967
Intelsat II F-3. Intelsat II F-3, also known as Canary Bird was a communications satellite operated by Intelsat. Launched in 1967 it was operated in geostationary orbit, spending most of its operational life at a longitude of 15 degrees west.

The third of four Intelsat II satellites to be launched, Intelsat II F-3 was built by Hughes Aircraft around the HS-303A satellite bus. It carried two transponders, which were powered by body-mounted solar cells generating 85 watts of power. The spacecraft had a mass of  at launch, decreasing through expenditure of propellant to  by the beginning of its operational life.

Intelsat II F-3 was launched atop a Delta E1 rocket flying from Launch Complex 17B at the Cape Canaveral Air Force Station. The launch took place at 01:30:12 on March 23, 1967, with the spacecraft entering a geosynchronous transfer orbit. It fired an SVM-1 apogee motor to place itself into its operational geostationary orbit. The spacecraft was operated at a longitude of 15° west, over the Atlantic Ocean. It was briefly relocated to 35° west in 1972, but had returned to 15° west by the following year.

It acquired the unofficial nickname Canary Bird because of the association of the mission with Maspalomas Station, the ground station which is located in the Canary Islands.

As of February 7, 2014 the derelict Intelsat II F-3 was in an orbit with a perigee of , an apogee of , inclination of 5.81 degrees and an orbital period of 23.94 hours.

References

Intelsat satellites
Hughes aircraft
Spacecraft launched in 1967
Transatlantic telecommunications
M74 light mortar. The M74 mortar is designed by Military Technical Institute in Yugoslavia. It is smooth bore, muzzle-loading, high-angle-of-fire weapon used for long-range indirect fire support. Today they are produced by Serbian company PPT Namenska and BNT from Bosnia and Herzegovina.

Description
This mortar can be deployed as infantry support for destruction of personnel and enemy firing positions, for opening routes through barbed wire obstacles and mine fields, for demolition of fortified objects, for destructing infrastructure elements, illumination and deploying smoke screen. 
The M74 model when disassembled could be carried by 3 soldiers thus having unique capabilities regarding transport in area with obstacles or in urban area compared with more heavier mortars.  M74 provides 12 rds per minute rate of fire and it is intended to be used to deliver 15-20 mines before moving to another position.  Since it is very light regarding its caliber it can be easily airdropped and parachuted to firing position. It uses NSB-4B sight for firing. Base-plate of M74 mortar is triangle shaped.

Specifications

Operators

Current operators

Former operators
	
  − Seized by Azerbaijan after the 2023 Azerbaijani offensive in Nagorno-Karabakh

See also 
 Soltam K6 
 Mortier 120mm Rayé Tracté Modèle F1
 120 KRH 92
 Light mortar 120mm M75

References

External links 
 

Artillery of Serbia
Infantry mortars
Mortars of Yugoslavia
120 mm mortars
Military equipment introduced in the 1980s
Intelsat II F-4. Intelsat II F-4 was a communications satellite operated by Intelsat. Launched in 1967 it was operated in geostationary orbit at a longitude of 176 degrees east and later 166 degrees west.

The fourth and last Intelsat II satellite to be launched, Intelsat II F-4 was built by Hughes Aircraft around the HS-303A satellite bus. It carried two transponders, which were powered by body-mounted solar cells generating 85 watts of power. The spacecraft had a mass of  at launch, decreasing through expenditure of propellant to  by the beginning of its operational life.

Intelsat II F-4 was launched atop a Delta E1 rocket flying from Launch Complex 17B at the Cape Canaveral Air Force Station. The launch took place at 00:45:00 UTC on September 28, 1967, with the spacecraft entering a geosynchronous transfer orbit. It fired an SVM-1 apogee motor to place itself into its operational geostationary orbit. The spacecraft was operated at a longitude of 176° east until 1970, before being moved to 166° west. In total the satellite remained in service for around three and a half years.

As of February 8, 2014 the derelict Intelsat II F-4 was in an orbit with a perigee of , an apogee of , inclination of 6.00 degrees and an orbital period of 23.95 hours.

References

Intelsat satellites
Hughes aircraft
Spacecraft launched in 1967