Numerical control is the automated control of machining tools and 3D printers by means of a computer. A CNC machine processes a piece of material to meet specifications by following a coded programmed instruction and without a manual operator. A CNC machine is a motorized maneuverable tool and a motorized maneuverable platform, which are both controlled by a computer, according to specific input instructions. Instructions are delivered to a CNC machine in the form of a sequential program of machine control instructions such as G-code and executed; the program can be written by a person or, far more generated by graphical computer-aided design software. In the case of 3D printers, the part to be printed is "sliced", before the instructions is generated. 3D printers use G-Code. CNC is a vast improvement over non-computerized machining that must be manually controlled or mechanically controlled by pre-fabricated pattern guides. In modern CNC systems, the design of a mechanical part and its manufacturing program is automated.
The part's mechanical dimensions are defined using CAD software and translated into manufacturing directives by computer-aided manufacturing software. The resulting directives are transformed into the specific commands necessary for a particular machine to produce the component, are loaded into the CNC machine. Since any particular component might require the use of a number of different tools – drills, etc. – modern machines combine multiple tools into a single "cell". In other installations, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case, the series of steps needed to produce any part is automated and produces a part that matches the original CAD; the first NC machines were built in the 1940s and 1950s, based on existing tools that were modified with motors that moved the tool or part to follow points fed into the system on punched tape. These early servomechanisms were augmented with analog and digital computers, creating the modern CNC machine tools that have revolutionized machining processes.
Motion is controlling multiple axes at least two, a tool spindle that moves in the Z. The position of the tool is driven by direct-drive stepper motors or servo motors in order to provide accurate movements, or in older designs, motors through a series of step-down gears. Open-loop control works as long as the forces are kept small enough and speeds are not too great. On commercial metalworking machines, closed loop controls are standard and required in order to provide the accuracy and repeatability demanded; as the controller hardware evolved, the mills themselves evolved. One change has been to enclose the entire mechanism in a large box as a safety measure with additional safety interlocks to ensure the operator is far enough from the working piece for safe operation. Most new CNC systems built. CNC-like systems are used for any process that can be described as operations; these include laser cutting, friction stir welding, ultrasonic welding and plasma cutting, spinning, hole-punching, gluing, fabric cutting, sewing and fiber placement, routing and placing, sawing.
Many other tools have CNC variants, including: Drills EDMs Embroidery machines Lathes Milling machine Canned cycle Wood routers Sheet metal works Tube and wire bending machines Hot-wire foam cutters Plasma cutters Water jet cutters Laser cutting Oxy-fuel Surface grinder Cylindrical grinders 3D printing Induction hardening machines Submerged arc welding Glass cutting CNC router In CNC, a "crash" occurs when the machine moves in such a way, harmful to the machine, tools, or parts being machined, sometimes resulting in bending or breakage of cutting tools, accessory clamps and fixtures, or causing damage to the machine itself by bending guide rails, breaking drive screws, or causing structural components to crack or deform under strain. A mild crash may not damage the machine or tools, but may damage the part being machined so that it must be scrapped. Many CNC tools have no inherent sense of the absolute position of tools when turned on, they must be manually "homed" or "zeroed" to have any reference to work from, these limits are just for figuring out the location of the part to work with it, are not any sort of hard motion limit on the mechanism.
It is possible to drive the machine outside the physical bounds of its drive mechanism, resulting in a collision with itself or damage to the drive mechanism. Many machines implement control parameters limiting axis motion past a certain limit in addition to physical limit switches. However, these parameters can be changed by the operator. Many CNC tools do not know anything about their working environment. Machines may have load sensing systems on spindle and axis drives, they blindly follow the machining code provided and it is up to an operator to detect if a crash is either occurring or about to occur, for the operator to manually abort the active process. Machines equipped with load sensors can stop axis or spindle movement in response to an overload condition, but this does not prevent a crash from occurring, it may only limit the damage resulting from the crash. Some crashes may not overload any axis or spindle drives. If the drive system is weaker
This page contains a list of military tactics. The meaning of the phrase is context sensitive, has varied over time, like the difference between "strategy" and "tactics". Exploiting prevailing weather – the tactical use of weather as a force multiplier has influenced many important battles throughout history, such as the Battle of Waterloo. Fire attacks – reconnaissance by fire is used by apprehensive soldiers when they suspect the enemy is nearby. Force concentration – the practice of concentrating a military force against a portion of an enemy force. Night combat – combat that takes place at night, it requires more preparation than combat during daylight and can provide significant tactical advantages and disadvantages to both the attacker and defender. Reconnaissance – a mission to obtain information by visual observation or other detection methods, about the activities and resources of the enemy or potential enemy, or about the meteorologic, hydrographic, or geographic characteristics of a particular area.
Smoke screening - the practice of creating clouds of smoke positioned to provide concealment, allowing military forces to advance or retreat across open terrain without coming under direct fire from the enemy. Penetration of the center: This involves the creation of a gap in the enemy line and its exploitation. Two ways of accomplishing this are separating enemy forces and using a reserve to exploit the gap that forms between them or having fast, elite forces smash at a specific point in the enemy line and, while reserves and holding forces hold your opponent and for the enemy's command or base. Attack from a defensive position: Establishing a strong defensive position from which to defend and attack your opponent. However, the defensive can result in ultimate defeat. Single envelopment: A strong flank beating its opponent opposite and, with the aid of holding attacks, attack an opponent in the rear. Sometimes, the establishment of a strong, hidden force behind a weak flank will prevent your opponent from carrying out their own single envelopment.
Double envelopment: Both flanks defeat their opponent opposite and launch a rear attack on the enemy center. Its most famous use was Hannibal's tactical masterpiece, the Battle of Cannae and was used by the Wehrmacht on the Eastern Front of World War II. Attack in oblique order: This involves placing your flanks in a slanted fashion or giving a vast part of your force to a single flank; the latter can be disastrous, due to the imbalance of force. Feigned retreat: Having a frontal force fake a retreat, drawing the opponent in pursuit and launching an assault with strong force held in reserve. However, a feigned retreat may devolve into a real one, such as in the Battle of Grunwald. Indirect approach: Having a minority of your force demonstrate in front of your opponent while the majority of your force advance from a hidden area and attack the enemy in the rear or flank. Crossing the "T": a classic naval maneuver which maximizes one side's offensive firepower while minimizing that of the opposing force.
Deception and misdirection Deception: Sun Tzu said that all war is based on deception back in the 4th century BC. Diversionary attacks, decoys. Perfidy: Combatants tend to have assumptions and ideas of rules and fair practices in combat, but the ones who raise surrender flags to lure their attackers in the open, or who act as stretcher bearers to deceive their targets, tend to be disliked. False flag: An ancient ruse de guerre – in the days of sail, it was permissible for a warship to fly the flag of an enemy power, so long as it properly hoisted its true colors before attacking. Wearing enemy uniforms and using enemy equipment to infiltrate or achieve surprise is permissible though they can be punished as spies if caught behind enemy lines. Demoralization: A process in psychological warfare that can encourage them to retreat, surrender, or defect rather than defeating them in combat. Disinformation Military camouflage Stealth technology Feint or diversionary attacks Electronic warfare Electronic countermeasures Electronic counter-countermeasures Radio silence – while traveling, a fleet will refrain from communicating by radio to avoid detection by enemy forces.
Force multiplication Use of surprise Parthian shot Hit-and-run tactics Irregular warfare Military strategy Tactical formation List of military strategies and concepts List of established military terms Use of bayonets for crowd control Tactical
Fenrir or Fenrisúlfr referred to as Hróðvitnir and Vánagandr, or Vanargand, is a monstrous wolf in Norse mythology. Fenrir, together with Hel and the World Serpent is a child of giantess Angrboða, he is attested in the Poetic Edda, compiled in the 13th century from earlier traditional sources, the Prose Edda and Heimskringla, written in the 13th century by Snorri Sturluson. In both the Poetic Edda and Prose Edda, Fenrir is the father of the wolves Sköll and Hati Hróðvitnisson, is a son of Loki, is foretold to kill the god Odin during the events of Ragnarök, but will in turn be killed by Odin's son Víðarr. In the Prose Edda, additional information is given about Fenrir, including that, due to the gods' knowledge of prophecies foretelling great trouble from Fenrir and his rapid growth, the gods bound him, as a result Fenrir bit off the right hand of the god Týr. Depictions of Fenrir have been identified on various objects, scholarly theories have been proposed regarding Fenrir's relation to other canine beings in Norse mythology.
Fenrir has been the subject of artistic depictions, he appears in literature. Fenrir is mentioned in three stanzas of the poem Völuspá and in two stanzas of the poem Vafþrúðnismál. In stanza 40 of the poem Völuspá, a völva divulges to Odin that, in the east, an old woman sat in the forest Járnviðr "and bred there the broods of Fenrir. There will come from them all one of that number to be a moon-snatcher in troll's skin." Further into the poem the völva foretells that Odin will be consumed by Fenrir at Ragnarök: Then is fulfilled Hlín's second sorrow, when Óðinn goes to fight with the wolf, Beli's slayer, against Surtr. Shall Frigg's sweet friend fall. In the stanza that follows the völva describes that Odin's "tall child of Triumph's Sire" will come to "strike at the beast of slaughter" and with his hands he will drive a sword into the heart of "Hveðrungr's son," avenging the death of his father. In the first of two stanzas mentioning Fenrir in Vafþrúðnismál Odin poses a question to the wise jötunn Vafþrúðnir: "Much I have travelled, much have I tried out, much have I tested the Powers.
In the stanza that follows Vafþrúðnir responds that Sól will bear a daughter before Fenrir attacks her, that this daughter shall continue the paths of her deceased mother through the heavens. In the Prose Edda, Fenrir is mentioned in three books: Skáldskaparmál and Háttatal. In chapter 13 of the Prose Edda book Gylfaginning, Fenrir is first mentioned in a stanza quoted from Völuspá. Fenrir is first mentioned in prose in chapter 25, where the enthroned figure of High tells Gangleri about the god Týr. High says that one example of Týr's bravery is that when the Æsir were luring Fenrir to place the fetter Gleipnir on the wolf, Týr placed his hand within the wolf's mouth as a pledge; this was done at Fenrir's own request. As a result, when the Æsir refused to release him, he bit off Týr's hand at a location "now called the wolf-joint", causing Týr to be one-handed and "not considered to be a promoter of settlements between people." In chapter 34, High describes Loki, says that Loki had three children with a woman named Angrboða located in the land of Jötunheimr.
High continues that, once the gods found that these three children were being brought up in the land of Jötunheimr, when the gods "traced prophecies that from these siblings great mischief and disaster would arise for them" the gods expected a lot of trouble from the three children due to the nature of the mother of the children, yet worse so due to the nature of their father. High says that Odin sent the gods to bring them to him. Upon their arrival, Odin threw Jörmungandr into "that deep sea that lies round all lands", threw Hel into Niflheim, bestowed upon her authority over nine worlds. However, the Æsir brought up the wolf "at home", only Týr had the courage to approach Fenrir, give Fenrir food; the gods noticed that Fenrir was growing every day, since all prophecies foretold that Fenrir was destined to cause them harm, the gods formed a plan. The gods prepared three fetters: The first strong, was called Leyding, they suggested that the wolf try his strength with it. Fenrir judged that it was not beyond his strength, so let the gods do what they wanted with it.
At Fenrir's first kick the bind snapped, Fenrir loosened himself from Leyding. The gods made a second fetter, twice as strong, named it Dromi; the gods asked Fenrir to try the new fetter, that should he break this feat of engineering, Fenrir would achieve great fame for his strength. Fenrir considered that the fetter was strong, yet that his strength had grown since he broke Leyding, yet that he would have to take some risks if he were to become famous. Fenrir allowed them to place the fetter; when the Æsir exclaimed that they were ready, Fenrir shook himself, knocked the fetter to the ground, strained hard, kicking with his feet, snapped the fetter – breaking it into pieces that flew far into the distance. High says that, as a result, to "loose from Leyding" or to "strike out of Dromi" have become sayings for when something is achieved with great effort; the Æsir started to fear that they would not be able to bind Fenrir, so Odin sent Freyr's messenger Skírnir down into the land of
Up First is a daily news podcast by the American media organization NPR, which releases an episode every weekday at 6am ET. Up First gives a brief overview of each news item, unlike some of their other popular news podcasts which provide a deep exploration of each story; the podcast was launched on April 5, 2017 in order to showcase the most prominent stories of the day in a digestible format. Up First is hosted by Rachel Martin, David Greene, Steve Inskeep, who discuss news items with experts; when Up First launched, it was intended to be a spin off of the popular NPR show Morning Edition, a morning news show that runs for several hours each weekday on NPR. For many people, Morning Edition was inaccessible to due the time in which it aired. For this reason, Up First was introduced to cater to the "more than three-fourths of NPR podcast listeners say they are “definitely” interested in short, daily audio news updates."Up First was NPR's solution to delivering the most broad overview of the show for the day, as many fans of Morning Edition didn't have the hours to dedicate to listening to the long show.
After Morning Edition first goes live at 5 am ET, NPR takes its first 10 minutes or so with Rachel Martin, David Greene, Steve Inskeep and edits that into the show that many know best as Up First. When the Morning Edition broadcast picks up again at 7 am ET, the first ten minutes of the broadcast are replaced with something new to keep the information fresh and not repetitive. Up First is compared to The New York Times' daily news podcast The Daily, the two podcasts have differences in how they are formatted. Meanwhile, NPR's Up First clocks in at around 10 minutes each day trying to make the days biggest news stories as accessible and digestible as possible; that being said and critics have been shown to favor The Daily over Up First. Up First is available to listen to on the NPR website, NPR One, anywhere else NPR podcasts are posted. List of daily news podcasts
Zénon Trudeau was a soldier and administrator who served as Lieutenant-governor of Upper Louisiana, New Spain, between 1792 and 1799. Born in New Orleans, Trudeau joined the Spanish Army in his youth, a place where he excelled, attaining the rank of Captain of the Regiment of Infantry and Lieutenant Colonel. In 1792, Zénon Trudeau was appointed Lieutenant-governor of Upper Louisiana, a position located in St. Louis. During his administration two new posts were established, he commanded the galiot La Fleche in an expedition from Natchez to St. Louis and back in the winter of 1793. In 1797, he granted lands which would be part of the state of Missouri to Joseph Conway and his family, to his friend Daniel Boone and his family. Trudeau left his position as Lieutenant-governor of Alta Luisiana in 1799, being succeeded by Charles de Hault de Lassus. Zénon Trudeau was the ancestor of Dr. Edward Garry Trudeau. Charles Trudeau, his brother
Gerard Lecuyer is a politician in Manitoba, Canada. He was a member of the Legislative Assembly of Manitoba from 1981 to 1988, a cabinet minister in the New Democratic Party government of Howard Pawley from 1983 to 1988; the son of Albert Lécuyer and Suzanne Delaloye, he grew up in Ste. Agathe and was educated at St. Boniface College and the University of Manitoba, working as an educator-administrator before entering public life, he directed special projects in the Bureau de l'Éducation français for the Department of Education, was a teacher in the St. Boniface school division, he spent five years in Africa as a teacher with the Canadian International Development Agency, was a member of the Franco-Manitoban Society. He was first elected to the Manitoba legislature in the election of 1981, scoring a comfortable victory in the east-Winnipeg riding of Radisson; the NDP won a majority government in this election, Lecuyer was named Government House Leader soon after the party's victory. He was a leading supporter of the legal re-entrenchment of French language services within the province.
Lecuyer was named Minister of Environment and Workplace Safety and Health on November 4, 1983. He won a easy re-election in the 1986 election, retained his cabinet positions until the NDP government was unexpectedly defeated in the legislature in 1988, he lost his seat to Liberal Allan Patterson by 2,000 votes in the 1988 provincial election. After leaving politics, Lecuyer worked as a consultant in Manitoba and the Yukon. From 1990 to 1994, he was executive director of the Francophone Parents Federation in Manitoba, he was appointed to the Manitoba Clean Environment Commission