omniomni/omni-engineering huggingface dataset:
True vertical depth. True vertical depth is the measurement of a straight line perpendicularly downwards from a horizontal plane.

In the petroleum industry, true vertical depth, abbreviated as TVD, is the measurement from the surface to the bottom of the borehole (or anywhere along its length) in a straight perpendicular line represented by line (a) in the image.

Line (b) is the actual borehole and its length would be considered the "measured depth" in oil industry terminology. The TVD is always equal to or less than (≤) the measured depth. If one were to imagine line (b) to be a piece of string, and further were to imagine it being pulled straight down, one would observe it to be longer than line (a). This example oil well would be considered a directional well because it deviates from a straight vertical line.

See also
 Depth in a well
 Driller's depth

References

Oilfield terminology
Petroleum geology
Vertical position
PdfTeX. 
The computer program pdfTeX is an extension of Knuth's  typesetting program TeX, and was originally written and developed into a publicly usable product by Hàn Thế Thành as a part of the work for his PhD thesis at the Faculty of Informatics, Masaryk University, Brno, Czech Republic. The idea of making this extension to TeX was conceived during the early 1990s, when Jiří Zlatuška and Phil Taylor discussed some developmental ideas with Donald Knuth at Stanford University. Knuth later met Hàn Thế Thành in Brno during his visit to the Faculty of Informatics to receive an honorary doctorate from Masaryk University.

Two prominent characteristics of pdfTeX are character protrusion, which generalizes the concept of hanging punctuation, and font expansion, an implementation of Hermann Zapf's ideas for improving the grayness of a typeset page. Both extend the core paragraph breaking routine. They are discussed in Thành's PhD thesis.

pdfTeX is included in most modern distributions of LaTeX and ConTeXt  (including TeX Live, MacTeX, and MiKTeX) and used as the default TeX engine.  The main difference between TeX and pdfTeX is that whereas TeX outputs DVI files, pdfTeX can output PDF files directly. This allows tight integration of PDF features such as hypertext links and tables of contents, using packages such as hyperref. On the other hand, packages (such as PSTricks) which exploit the earlier conversion process of DVI-to-PostScript may fail, although replacements such as PGF/TikZ have been written.  Direct embedding of PostScript graphics is no longer functional, and one has to use a program such as eps2pdf to convert EPS files to PDF, which can then be directly inserted by pdfTeX.

It is possible to obtain DVI output from pdfTeX. This DVI output should be identical to that of TeX, unless pdfTeX's extra microtypography features have been activated. Moreover, since LaTeX, ConTeXt et al. are simply macro packages for TeX, they work equally well with pdfTeX. Hence, pdflatex, for example, calls the pdfTeX program using the standard LaTeX macros to typeset LaTeX documents, whereas it was the default rendering engine for ConTeXt documents. Current versions of ConTeXt use
LuaMetaTeX as default rendering engine.

Features 
pdfTeX has several features not available in standard TeX:
 Native TrueType and Type 1 font embedding
 Micro-typographic extensions such as margin kerning and font expansion
 Direct access to PDF-specific features such as hyperlinks, tables of contents and document information

See also 

 List of TeX extensions
 List of PDF software
 LuaTeX
 XeTeX

References

External links
 pdfTeX project page
 pdfTeX manual
  Micro-typographic extensions to the TeX typesetting system - dissertation by Hàn Thế Thành
  2008 interview

Free PDF software
Free TeX software
Sea skimming. Sea skimming is a technique many anti-ship missiles and some fighter or strike aircraft use to avoid radar, infrared detection, and to lower probability of being shot down during their approach to the target.

Method 
Sea-skimming anti-ship missiles try to fly as low as is practically achievable, which is almost always below 50 meters (150 ft), and is often near 2 meters (6 ft). When under attack, a warship can detect sea-skimming missiles only after they appear over the horizon (about 28 to 46 km from the ship), allowing about 25 to 60 seconds of warning.

Advantages 
By flying low to the sea, missiles decrease the range at which the target ships can detect them by a significant amount. Flying at a lower altitude increases the amount of time the missile is under the horizon from the perspective of the target ship, making it harder to detect due to radar clutter from the sea and similar effects. The real-life success of sea skimming depends on its exact implementation, the sophistication of the detection equipment, as well as the infrared and radar signature of the missile. Sea skimming can significantly reduce the available response time that a ship's missile defenses have to work within, making these missiles significantly harder to defend against. Sea skimming can also increase the range of a missile, by relying on ground effects.

Disadvantages 
The use of sea skimming increases the risk of water impact by the missile before reaching the target due to weather conditions, rogue waves, software bugs and other factors. Sea skimming also hinders target acquisition, as many of the principles that hinder the target's detection of the missile also hinder the missile's detection of the target. Sea skimming involves a significant computational load, increasing the required processing power and cost.

Possible defenses 
Several systems are capable of defeating sea skimming weapons.

Gun-based CIWS

Missile-based CIWS

Chaff

ECM

Use in major wars 
French-made Exocet missiles were used by Argentina in the Falklands War (including the mortal wounding of HMS Sheffield) and by Iraq against USS Stark in the Persian Gulf during the Iran–Iraq War. The Argentinian pilots of the Super Étendard planes that attacked HMS Sheffield were also skimming the sea at very low level. They increased their altitude only for a very short period to get final target information for the attack with their Agave radars. During the 2022 Russian Invasion of Ukraine, two Ukrainian-made R-360 Neptune sea-skimming cruise missiles were claimed to have struck and sank the Russian cruiser Moskva.

See Also 

 Lofting (Missile technique)

References 

Anti-ship missiles
Low flying
Missile types
Naval warfare
Renfe Class 276. The Renfe Class 276 is a class of DC electric locomotive which was used by the Spanish rail operator Renfe. Based on the French SNCF Class CC 7100, the Class 276 was modified to fit the Spanish  gauge and use a 3000V DC overhead supply. More than 130 locomotives were supplied to Renfe in 1956.

History
Originally classified by Renfe as 76xx and 86xx (the example in the photograph is number 7685), the 276 series was based on the French SNCF Class CC 7100. The majority of the 276s were manufactured in Spain by various locomotive works, including CAF. Due to their Gallic origins, the locomotives were given the nickname Francesa (English translation: French).

A total of 136 units were built during between 1956 and 1965, ten of which were modernised and classed as 276.2xx.

Technical data
Since the 276 is a Co′Co′ locomotive, it is equipped with two three-axled bogies – each of which is powered by three traction motors. This six traction motor configuration provides the locomotive with a total power output of  and a maximum speed of . Of the 136 examples produced, only 36 have been adapted for use in multiple unit operations: these are unit numbers 276.101 through 276.137, inclusive.

Current status
This class was withdrawn from regular service by December 2014. However two locomotives are still in existence and these locomotives currently held in reserve in Madrid, are shortly (August 2017) expected to be transferred to the Museum and Railway Centre in Mora La Nova, 30 km inland from Tarragona in Southern Catalonia. From these two machines, one is expected to be restored to full working order and in as near original condition as possible. The two locomotives will swap certain parts to aid quicker restoration of one to full working order. The other will most likely be just cosmetically restored. (Details Courtesy International Liaison Officer - Mora La Nova Museum and Railway Centre, August 2017).

References

External links

Co′Co′ locomotives
Electric locomotives of Spain
276
Railway locomotives introduced in 1956
5 ft 6 in gauge locomotives
Co′Co′ electric locomotives of Europe
Iberian gauge locomotives
Phoxim. Phoxim is an organophosphate insecticide that is produced by the Bayer corporation.  It is an analogous dimethyl ester and an organothiophosphate acaricide.  It is allowed for use in limited applications in the European Union. It is banned for use on crops in the European Union since 22 December 2007.

It is used in veterinary medicine to treat ectoparasitic acarids.

This pesticide should be used with caution since some insects like Helicoverpa assulta become even more resistant when exposed.

References

External links 

Acetylcholinesterase inhibitors
Organophosphate insecticides
Nitriles
Organothiophosphate esters
Oxime esters
Ethyl esters
Mud balance. A mud balance, also known as a mud scale is a device used to measure the density (weight) of drilling fluid, cement or any type of liquid or slurry.

Description and operation
It consists of a graduated beam with a bubble level and a weight slider along its length and a cup with a lid on one end. The cup is used to hold a fixed amount of fluid so it can be weighed.  A slider-weight can be moved along the beam, and a bubble indicates when the beam is level. Density is read at the point where the slider-weight sits on the beam at level.

Calibration is done using a liquid of known density (often fresh water) by adjusting the counter weight. Typical balances are not pressurized, but a pressurized mud balance operates in the same manner.

Reason for use
There is no reliable visual method of determining the density of drilling mud; the mud balance is the most reliable and simple way of making the determination.

References

Drilling fluid
Space Development and Test Wing. The Space Development and Test Wing (SDTW) was a unit of Air Force Space Command's Space and Missile Systems Center of the United States Air Force. The wing is located at Kirtland Air Force Base in Albuquerque, New Mexico.

The unit was combined with another Space and Missile Systems Center directorate and is now known as the Advanced Systems and Development Directorate.

Mission
The Space Development and Test Directorate develops, tests and evaluates Air Force space systems, executes advanced space development and demonstration projects, and rapidly transitions capabilities to the warfighter.

History
The Space Development and Test Wing was activated 1 August 2006. Prior to that, Detachment 12 of the Space and Missile Systems Center had been activated at Kirtland AFB 29 June 2001, taking responsibility for research, developmental test and evaluation organizations that had been co-located at Kirtland AFB alongside the Air Force Research Laboratory Space Vehicles and Directed Energy Directorates.

 Lineage
 Detachment 2, Space and Missile Systems Center, Onizuka AS, CA
 SMC, Test and Evaluation Directorate, Kirtland AFB, NM
 Detachment 12, Space and Missile Systems Center, Kirtland AFB, NM (activated 29 June 2001)
 Space Development and Test Wing, Kirtland AFB, NM (activated 1 Aug 2006)
 Advanced Systems and Development Directorate, Kirtland AFB, NM
 Past Directors and Commanders
 Craig Martin, Colonel, USAF (retired)
 James Ford, Colonel, USAF (retired)
 Ralph Monfort, Colonel, USAF (retired)

Operations

Units
The Space Development and Test Wing is divided into two Groups, the Space Development Group and the Space Test Group.

 Space Development Group
 Responsive Space Squadron
 Responsive Satellite Command and Control Division
 Human Spaceflight Payloads Division  - Houston, TX
Space Test Group
 Space Test Squadron
 SOC 96 - Schriever AFB
  SOC 97 - Kirtland AFB
 Space Test Operations Squadron
 Launch Test Squadron

References

See also
 Space Test Program
 Space and Missile Systems Center
 C/NOFS
 STP-S26
 Vandenberg AFB Launch Schedule

Military units and formations in New Mexico
Space wings of the United States Air Force
Test wings of the United States Air Force
Betagel. Betagel (βゲル in Japanese) is a material invented in Japan that utilizes gel and silicone to absorb violent shocks.

Japanese researchers developed "Alphagel,", which was principally used in the manufacture of sneakers and as a shock-absorber for tennis racquets.  Betagel, a more effective formulation, was so named according to the Greek Alphabet (alpha, beta, gamma etc.), in which letters also serve as numerals. It is also principally used in sneakers.

The gel is also used in scientific applications.

References

External links 
geltec.co.jp 
tech-jam.com 

Brand name materials
Journal of Zhejiang University. The Journal of Zhejiang University (Traditional Chinese: 浙江大學學報, Simplified Chinese: 浙江大学学报) is a peer-reviewed academic journal series published by the Zhejiang University Press. There are eight sub-journals, covering the fields of science, engineering, medicine, humanities, and social sciences.

Journals 
 Journal of Zhejiang University Science A: Applied Physics and Engineering (in collaboration with Springer Science+Business Media)
 Journal of Zhejiang University Science B: Biomedicine & Biotechnology (in collaboration with Springer Science+Business Media)
 Frontiers of Information Technology & Electronic Engineering (Since 2015) (in collaboration with Springer Science+Business Media and the Chinese Academy of Engineering; formerly Journal of Zhejiang University Science C)
 Journal of Zhejiang University: Engineering (in Chinese)
 Journal of Zhejiang University: Agriculture & Life Science (in Chinese)
 Journal of Zhejiang University: Science (in Chinese)
 Journal of Zhejiang University: Medicine/Medical Sciences (in Chinese)
 Journal of Zhejiang University: Humanities & Social Sciences (in Chinese)

External links 
 

Zhejiang University Press academic journals
Academic journals published by university presses
Academic journal series
Weight on bit. Weight on bit (WOB), as expressed in the oil industry, is the amount of downward force exerted on the drill bit and is normally measured in thousands of pounds.

Weight on bit is provided by drill collars, which are thick-walled tubular pieces machined from solid bars of steel, usually plain carbon steel but sometimes of nonmagnetic nickel-copper alloy or other nonmagnetic premium alloys. Gravity acts on the large mass of the collars to provide the downward force needed for the bits to efficiently break rock. To accurately control the amount of force applied to the bit, the driller carefully monitors the surface weight measured while the bit is just off the bottom of the wellbore. Next, the drillstring (and the drill bit), is slowly and carefully lowered until it touches bottom. After that point, as the driller continues to lower the top of the drillstring, more and more weight is applied to the bit, and correspondingly less weight is measured as hanging at the surface. If the surface measurement shows 20,000 pounds [9080 kg] less weight than with the bit off bottom, then there should be 20,000 pounds force on the bit (in a vertical hole). Some downhole Measurement While Drilling (MWD) sensors can measure weight-on-bit more accurately and transmit the data to the surface.

References

Oilfield terminology
Caja project. Caja (pronounced  ) was a Google project for sanitizing third party HTML, CSS and JavaScript. On January 31, 2021, Google archived the project due to known vulnerabilities and lack of maintenance to keep up with the latest web security research, recommending instead the Closure toolkit.

The Caja project was led by Jasvir Nagra with the JavaScript portion designed by Google research scientist Mark S. Miller in 2008 as a JavaScript implementation for "virtual iframes" based on the principles of object-capabilities. It would take JavaScript (technically, ECMAScript 5 strict mode code), HTML, and CSS input and rewrite it into a safe subset of HTML and CSS, plus a single JavaScript function with no free variables.  That means the only way such a function could modify an object, was if it was given a reference to the object by the host page.  Instead of giving direct references to DOM objects, the host page typically gives references to wrappers that sanitize HTML, proxy URLs, and prevent redirecting the page; this allowed Caja to prevent certain phishing and cross-site scripting attacks, and prevent downloading malware.  Also, since all rewritten programs ran in the same frame, the host page could allow one program to export an object reference to another program; then inter-frame communication was simply method invocation.

The word "caja" is Spanish for "box" or "safe" (as in a bank), the idea being that Caja could safely contain JavaScript programs as well as being a capabilities-based JavaScript.

Caja was used by Google in its Google Apps Script products. In 2008 MySpace and Yahoo! had both deployed a very early version of Caja.

See also 
 Joe-E, an object-capability subset of Java
 E

References

External links 

 Caja project home page
 Caja project source code
 Caja playground
 Caja draft specification: "Safe active content in sanitized JavaScript", Mark S. Miller, Mike Samuel, Ben Laurie, Ihab Awad, Mike Stay
 Yahoo!/Google Caja Javascript Sandbox

Capability systems
Transformation languages
Blackstone Viaduct. The Blackstone Viaduct, or the New York & New England Railroad Viaduct is a historic viaduct in Blackstone, Massachusetts.  The viaduct was built in 1872 by the Boston, Hartford and Erie Railroad and the American Bridge Company.  The viaduct is  long structure, consisting of masonry arches and earthen embankments in the Massachusetts portion of the village of Waterford.  It runs from the Blackstone River in the east to a still-watered section of the defunct Blackstone Canal to the west.  The most prominent portion of the structure is an 800-foot earthen embankment running west from the river that is  high, and then a  multiple-arch masonry bridge constructed out of granite which was sheathed in concrete in 1918.  The structure was listed on the National Register of Historic Places in 2002.

History

The viaduct was built as part of a project by the Boston, Hartford and Erie (BH&E) to build a complete run between New York City and Boston.  The first leg of this route, between Blackstone and Boston, was opened in 1849, and was purchased by the BH&E in 1867.  That company completed the connection between Blackstone and New Haven, Connecticut in 1873, part of which included construction of this viaduct, replacing an older wooden trestle.  By the early 20th century, some of the viaduct's arches were in deteriorating condition, and were reinforced with concrete in 1918.  The bridge over Canal Street was replaced in 1917.  The viaduct is one of the largest of the state's 19th-century masonry bridge structures, second in size only to the Canton Viaduct. In the late 1960s, floodwaters washed away an abutment of the adjoining trestle to the east, ending service over the viaduct.

The Massachusetts Department of Conservation and Recreation (DCR) purchased a section of the right-of-way, including the viaduct, in the 1980s for possible conversion to a rail trail. A 2010 DCR study indicated the viaduct was in poor condition and that trail conversion would require it to be removed. However, after local advocacy, a second study in 2015 found that it was sufficiently sound to be restored. A  segment of trail west of the viaduct opened in 2017 as part of both the Southern New England Trunkline Trail (SNETT), which follows the BH&E, and the Blackstone River Greenway. Restoration work on the Canal Street bridge took place in 2019–2020.

Restoration of the viaduct itself began in 2022. On November 22, 2024, the DCR opened  of trail from Canal Street over the viaduct and curving south to the Rhode Island line, connecting to an existing portion of trail in Rhode Island. The restoration and trail construction project cost $14 million.

See also
National Register of Historic Places listings in Worcester County, Massachusetts

References

External links

Railroad bridges on the National Register of Historic Places in Massachusetts
New York and New England Railroad
Buildings and structures in Blackstone, Massachusetts
Railroad bridges in Massachusetts
National Register of Historic Places in Worcester County, Massachusetts
Viaducts in the United States
ROF Kirkby. ROF Kirkby, (Filling Factory No. 7) was a large World War II Royal Ordnance Factory (ROF) filling munitions. The factory was based in the rural area of Kirkby, on the outskirts of Liverpool, Merseyside. The rural location was to reduce the potential damage from any accidental explosions. Munitions were produced from September 1940 to March 1946.

History 
Original planning for the site began at Royal Arsenal, Woolwich, with Sir Alex Gibson acting as consultant and Holloway Brothers the contractors. When completed the factory consisted of more than 1,000 buildings,  of roads and  of railway lines along with a station and had cost £8,500,000 (approx. £1,800 million inflation adjusted as share of GDP). As a way to minimise the risk of damage in the event of an explosion taking place the buildings were widely spaced and some were mounded up to the eaves.

In July 1940 Lawrence Gale from the Royal Arsenal, Woolwich, was appointed the Superintendent, taking 9 staff with him, and when the first shells rolled off the assembly line in September 1940 there were only between 50 and 100 employees. By the summer of 1941 this had risen to 10,000 before rising to a peak of around 23,000 employees, most of whom were women. Medical treatment rooms were built onsite in order to cater to such a large workforce. When the Royal Arsenal, Woolwich was bombed, it had to be closed down and many workers and a large amount of material were transferred to ROF Kirkby. In order to house these employees, 200 houses for key workers were built in the area and a YWCA hostel was built to house 1,000 women. The factory employed a three shift system so that production was continuous, combining with the transport system so that as it dropped off one shift of employees it would take home another shift. In December 1940, a railway station was opened on the Liverpool to Wigan Wallgate line to service the factory. It closed in March 1946.  

The ROF was eventually closed in March 1946, having been designated a War Duration Only ROF. It had produced around ten per cent of all the ammunition used in World War II by Britain. Afterwards the site was developed by Liverpool Corporation as an industrial estate and played a large part in the growth of Kirkby from a population of barely over 3,000 in 1951 to over 52,000 by 1961.

Accidents 
There were two explosions at Kirkby ROF, one in February 1944 and one on 15 September 1944. Two people were killed in the first accident and 14 killed and 11 injured in the second. It took three months of work to clear 4,000 bombs which were buried in the rubble after the second accident, with a total of 37 awards for bravery and distinguished conduct made by the King. These included both the George Cross and George Medal to Arthur Bywater, for his brave conduct during both explosions.

References

External links 
ROF Kirkby Sports Club
Knowsley Local History: Kirkby Royal Ordnance Factory

Kirkby
Kirkby
Kirkby
Royal Ordnance Factories in England