sentence-transformers/squad huggingface dataset:
Passage: Nothing in the principle of any of the motors described above requires that the iron (steel) portions of the rotor actually rotate. If the soft magnetic material of the rotor is made in the form of a cylinder, then (except for the effect of hysteresis) torque is exerted only on the windings of the electromagnets. Taking advantage of this fact is the coreless or ironless DC motor, a specialized form of a PM DC motor. Optimized for rapid acceleration, these motors have a rotor that is constructed without any iron core. The rotor can take the form of a winding-filled cylinder, or a self-supporting structure comprising only the magnet wire and the bonding material. The rotor can fit inside the stator magnets; a magnetically soft stationary cylinder inside the rotor provides a return path for the stator magnetic flux. A second arrangement has the rotor winding basket surrounding the stator magnets. In that design, the rotor fits inside a magnetically soft cylinder that can serve as the housing for the motor, and likewise provides a return path for the flux.

Question: A coreless DC motor is distinguished by what?

Question: What is absent in a coreless DC motor?

Question: What forms can the rotor take?
Passage: Because the rotor is much lighter in weight (mass) than a conventional rotor formed from copper windings on steel laminations, the rotor can accelerate much more rapidly, often achieving a mechanical time constant under one ms. This is especially true if the windings use aluminum rather than the heavier copper. But because there is no metal mass in the rotor to act as a heat sink, even small coreless motors must often be cooled by forced air. Overheating might be an issue for coreless DC motor designs.

Question: What is a likely problem of coreless DC motors?

Question: How does a coreless rotor compare to traditional rotors in terms of weight?

Question: What advantage does a coreless rotor have over traditional variants?

Question: The lack of a metal mass in the core causes what function to be absent?

Question: How is a coreless motor cooled?
Passage: These motors were originally invented to drive the capstan(s) of magnetic tape drives in the burgeoning computer industry, where minimal time to reach operating speed and minimal stopping distance were critical. Pancake motors are still widely used in high-performance servo-controlled systems, robotic systems, industrial automation and medical devices. Due to the variety of constructions now available, the technology is used in applications from high temperature military to low cost pump and basic servos.

Question: What was the original purpose for pancake motors?

Question: What are advantages of pancake motors?

Question: For what type of military applications are pancake motors currently used?

Question: What type of servo-controlled systems use pancake motors?
Passage: A servomotor is a motor, very often sold as a complete module, which is used within a position-control or speed-control feedback control system mainly control valves, such as motor-operated control valves. Servomotors are used in applications such as machine tools, pen plotters, and other process systems. Motors intended for use in a servomechanism must have well-documented characteristics for speed, torque, and power. The speed vs. torque curve is quite important and is high ratio for a servo motor. Dynamic response characteristics such as winding inductance and rotor inertia are also important; these factors limit the overall performance of the servomechanism loop. Large, powerful, but slow-responding servo loops may use conventional AC or DC motors and drive systems with position or speed feedback on the motor. As dynamic response requirements increase, more specialized motor designs such as coreless motors are used. AC motors' superior power density and acceleration characteristics compared to that of DC motors tends to favor PM synchronous, BLDC, induction, and SRM drive applications.

Question: What may servo motors be used for?

Question: What must be well understood when applying a servo motor for use?

Question: What factors limit performance of servo motors?

Question: Large, slow servos can use what types of motors?

Question: When might coreless motors be used in servo applications?
Passage: A servo system differs from some stepper motor applications in that the position feedback is continuous while the motor is running; a stepper system relies on the motor not to "miss steps" for short term accuracy, although a stepper system may include a "home" switch or other element to provide long-term stability of control. For instance, when a typical dot matrix computer printer starts up, its controller makes the print head stepper motor drive to its left-hand limit, where a position sensor defines home position and stops stepping. As long as power is on, a bidirectional counter in the printer's microprocessor keeps track of print-head position.

Question: How do servo motors differ from stepper motors?

Question: How does a stepper system achieve stability?

Question: What makes a printer home switch work?

Question: What kind of counter keeps track of a print head's position?

Question: A stepper system's motor is relied on to not do what?
Passage: Stepper motors are a type of motor frequently used when precise rotations are required. In a stepper motor an internal rotor containing PMs or a magnetically soft rotor with salient poles is controlled by a set of external magnets that are switched electronically. A stepper motor may also be thought of as a cross between a DC electric motor and a rotary solenoid. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a synchronous motor, in its application, the stepper motor may not rotate continuously; instead, it "steps"—starts and then quickly stops again—from one position to the next as field windings are energized and de-energized in sequence. Depending on the sequence, the rotor may turn forwards or backwards, and it may change direction, stop, speed up or slow down arbitrarily at any time.

Question: When are stepper motors most useful?

Question: What two devices can describe a stepper motor?

Question: What do stepper motor rotors allign themselves with?

Question: How does a stepper motor differ from a synchronous motor?

Question: What types of velocities and positions is the stepper motor capable of?
Passage: Simple stepper motor drivers entirely energize or entirely de-energize the field windings, leading the rotor to "cog" to a limited number of positions; more sophisticated drivers can proportionally control the power to the field windings, allowing the rotors to position between the cog points and thereby rotate extremely smoothly. This mode of operation is often called microstepping. Computer controlled stepper motors are one of the most versatile forms of positioning systems, particularly when part of a digital servo-controlled system.

Question: What is a trait of a sophisticated stepper motor?

Question: What does proportinal control of the field windings in a stepper motor achieve?

Question: What is another name for smooth rotation?

Question: With what other device are stepper motors most versatile?
Passage: Stepper motors can be rotated to a specific angle in discrete steps with ease, and hence stepper motors are used for read/write head positioning in computer floppy diskette drives. They were used for the same purpose in pre-gigabyte era computer disk drives, where the precision and speed they offered was adequate for the correct positioning of the read/write head of a hard disk drive. As drive density increased, the precision and speed limitations of stepper motors made them obsolete for hard drives—the precision limitation made them unusable, and the speed limitation made them uncompetitive—thus newer hard disk drives use voice coil-based head actuator systems. (The term "voice coil" in this connection is historic; it refers to the structure in a typical (cone type) loudspeaker. This structure was used for a while to position the heads. Modern drives have a pivoted coil mount; the coil swings back and forth, something like a blade of a rotating fan. Nevertheless, like a voice coil, modern actuator coil conductors (the magnet wire) move perpendicular to the magnetic lines of force.)

Question: Why were stepper motors abandoned in computer drive designs?

Question: What do newer computer drives use instead of stepper motors?

Question: In what direction do modern coil actuators move?

Question: To what device does the term, "voice coil" historically refer?
Passage: Stepper motors were and still are often used in computer printers, optical scanners, and digital photocopiers to move the optical scanning element, the print head carriage (of dot matrix and inkjet printers), and the platen or feed rollers. Likewise, many computer plotters (which since the early 1990s have been replaced with large-format inkjet and laser printers) used rotary stepper motors for pen and platen movement; the typical alternatives here were either linear stepper motors or servomotors with closed-loop analog control systems.

Question: List two alternatives to rotary stepper motors in printer applications.

Question: In scanners, what do stepper motors move?

Question: In printers and copiers, what do stepper motors move?
Passage: Since the armature windings of a direct-current or universal motor are moving through a magnetic field, they have a voltage induced in them. This voltage tends to oppose the motor supply voltage and so is called "back electromotive force (emf)". The voltage is proportional to the running speed of the motor. The back emf of the motor, plus the voltage drop across the winding internal resistance and brushes, must equal the voltage at the brushes. This provides the fundamental mechanism of speed regulation in a DC motor. If the mechanical load increases, the motor slows down; a lower back emf results, and more current is drawn from the supply. This increased current provides the additional torque to balance the new load.

Question: Voltage opposing the motor supply voltage is called what?

Question: EMP is proportional to what?

Question: Voltage at the brushes is equal to what?

Question: If load increases, what happens to current drawn?
Passage: All the electromagnetic motors, and that includes the types mentioned here derive the torque from the vector product of the interacting fields. For calculating the torque it is necessary to know the fields in the air gap . Once these have been established by mathematical analysis using FEA or other tools the torque may be calculated as the integral of all the vectors of force multiplied by the radius of each vector. The current flowing in the winding is producing the fields and for a motor using a magnetic material the field is not linearly proportional to the current. This makes the calculation difficult but a computer can do the many calculations needed.

Question: What needs to be known to calculate torque?

Question: How are the many calculations to determine torque done?

Question: How is torque determined?

Question: What is the formulia to determine torque?
Passage: When optimally designed within a given core saturation constraint and for a given active current (i.e., torque current), voltage, pole-pair number, excitation frequency (i.e., synchronous speed), and air-gap flux density, all categories of electric motors or generators will exhibit virtually the same maximum continuous shaft torque (i.e., operating torque) within a given air-gap area with winding slots and back-iron depth, which determines the physical size of electromagnetic core. Some applications require bursts of torque beyond the maximum operating torque, such as short bursts of torque to accelerate an electric vehicle from standstill. Always limited by magnetic core saturation or safe operating temperature rise and voltage, the capacity for torque bursts beyond the maximum operating torque differs significantly between categories of electric motors or generators.

Question: What are factors that determine shaft torque?

Question: Whate decides the size of an electromagnetic core?

Question: What limits excessive torque?
Passage: The brushless wound-rotor synchronous doubly-fed (BWRSDF) machine is the only electric machine with a truly dual ported transformer circuit topology (i.e., both ports independently excited with no short-circuited port). The dual ported transformer circuit topology is known to be unstable and requires a multiphase slip-ring-brush assembly to propagate limited power to the rotor winding set. If a precision means were available to instantaneously control torque angle and slip for synchronous operation during motoring or generating while simultaneously providing brushless power to the rotor winding set, the active current of the BWRSDF machine would be independent of the reactive impedance of the transformer circuit and bursts of torque significantly higher than the maximum operating torque and far beyond the practical capability of any other type of electric machine would be realizable. Torque bursts greater than eight times operating torque have been calculated.

Question: What is the only device with dual ported transformer circuit topology?

Question: What is a brushless wound-rotor?

Question: How does a brushless wound rotor achieve stability?

Question: What is the theoretical maximum of a brushless wound rotor?
Passage: The continuous torque density of conventional electric machines is determined by the size of the air-gap area and the back-iron depth, which are determined by the power rating of the armature winding set, the speed of the machine, and the achievable air-gap flux density before core saturation. Despite the high coercivity of neodymium or samarium-cobalt PMs, continuous torque density is virtually the same amongst electric machines with optimally designed armature winding sets. Continuous torque density relates to method of cooling and permissible period of operation before destruction by overheating of windings or PM damage.

Question: What determines continuous torque density?

Question: What three elements determine the size of the air-gap area and back iron depth?

Question: What does continuous torque density refer to?

Question: How does continuous torque density vary between well designed motors?
Passage: An electrostatic motor is based on the attraction and repulsion of electric charge. Usually, electrostatic motors are the dual of conventional coil-based motors. They typically require a high-voltage power supply, although very small motors employ lower voltages. Conventional electric motors instead employ magnetic attraction and repulsion, and require high current at low voltages. In the 1750s, the first electrostatic motors were developed by Benjamin Franklin and Andrew Gordon. Today the electrostatic motor finds frequent use in micro-electro-mechanical systems (MEMS) where their drive voltages are below 100 volts, and where moving, charged plates are far easier to fabricate than coils and iron cores. Also, the molecular machinery which runs living cells is often based on linear and rotary electrostatic motors.[citation needed]

Question: What type of motor is based on the attraction and repulsion of electric charge?

Question: What are electrostatic motors like two of?

Question: What type of power supply do electrostatic motors usually have?

Question: What two inventors developed the first electrostatic motors?

Question: Micro-electro mechanical systems prefer what type of motor?
Passage: Switzerland (/ˈswɪtsərlənd/), officially the Swiss Confederation (Latin: Confoederatio Helvetica, hence its abbreviation CH), is a country in Europe. While still named the "Swiss Confederation" for historical reasons, modern Switzerland is a federal directorial republic consisting of 26 cantons, with Bern as the seat of the federal authorities, called Bundesstadt ("federal city").[note 3] The country is situated in Western and Central Europe,[note 4] and is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland is a landlocked country geographically divided between the Alps, the Swiss Plateau and the Jura, spanning an area of 41,285 km2 (15,940 sq mi). While the Alps occupy the greater part of the territory, the Swiss population of approximately 8 million people is concentrated mostly on the Plateau, where the largest cities are to be found: among them are the two global and economic centres, Zürich and Geneva.

Question: What is the official name of Switzerland?

Question: What type of government does Switzerland have?

Question: How many cantons are in Switzerland's federal directorial republic?

Question: What 3 geographical features divide Switzerland?

Question: What is the population of Switzerland?
Passage: The establishment of the Swiss Confederation is traditionally dated to 1 August 1291, which is celebrated annually as the Swiss National Day. The country has a long history of armed neutrality—it has not been in a state of war internationally since 1815—and did not join the United Nations until 2002. Nevertheless, it pursues an active foreign policy and is frequently involved in peace-building processes around the world. In addition to being the birthplace of the Red Cross, Switzerland is home to numerous international organizations, including the second largest UN office. On the European level, it is a founding member of the European Free Trade Association, but notably it is not part of the European Union, nor the European Economic Area. However the country does participate in the Schengen Area and the EU's single market through a number of bilateral treaties.

Question: What is the traditional date of the establishment of the Swiss Confederation?

Question: What year did Switzerland join the United Nations?

Question: What country is the birthplace of the Red Cross?

Question: In what year was Switzerland last involved in a war internationally?

Question: What Swiss holiday is celebrated on August 1st every year?
Passage: Straddling the intersection of Germanic and Romance Europe, Switzerland comprises four main linguistic and cultural regions: German, French, Italian and Romansh. Therefore, the Swiss, although predominantly German-speaking, do not form a nation in the sense of a common ethnicity or language; rather, Switzerland's strong sense of identity and community is founded on a common historical background, shared values such as federalism and direct democracy, and Alpine symbolism. Due to its linguistic diversity, Switzerland is known by a variety of native names: Schweiz [ˈʃvaɪts] (German);[note 5] Suisse [sɥis(ə)] (French); Svizzera [ˈzvittsera] (Italian); and Svizra [ˈʒviːtsrɐ] or [ˈʒviːtsʁːɐ] (Romansh).[note 6]

Question: Which four main linguistic and cultural regions make up Switzerland?

Question: What is the predominant language in Switzerland?

Question: What do the French Swiss call Switzerland?

Question: What do the German Swiss call Switzerland?

Question: What do the Italian Swiss call Switzerland?
Passage: Switzerland is one of the richest and wealthiest countries in the world. Switzerland ranks top or close to the top in several metrics of national performance, including government transparency, civil liberties, quality of life, economic competitiveness, and human development. It has the highest nominal wealth (financial and non-financial assets) per adult in the world according to Credit Suisse and the eighth-highest per capita gross domestic product on the IMF list. Zürich and Geneva have each been ranked among the top cities with the highest quality of life in the world, with the former ranked 2nd globally, according to Mercer.

Question: How does Switzerland rank worldwide in areas such as quality of life and civil liberties?

Question: Which country has the highest nominal wealth per adult in the world according to Credit Suisse?

Question: Which two Swiss cities have been ranked as having the highest quality of life in the world?

Question: What assets are included in nominal wealth?

Question: What is Switzerland's ranking for per capita gross domestic product on the IMF list?
Passage: The English name Switzerland is a compound containing Switzer, an obsolete term for the Swiss, which was in use during the 16th to 19th centuries. The English adjective Swiss is a loan from French Suisse, also in use since the 16th century. The name Switzer is from the Alemannic Schwiizer, in origin an inhabitant of Schwyz and its associated territory, one of the Waldstätten cantons which formed the nucleus of the Old Swiss Confederacy. The name originates as an exonym, applied pars pro toto to the troops of the Confederacy. The Swiss began to adopt the name for themselves after the Swabian War of 1499, used alongside the term for "Confederates", Eidgenossen (literally: comrades by oath), used since the 14th century.

Question: What was the Swiss term for Switzerland during the 16th - 19th centuries?

Question: Where did the English adjective Swiss originate from?

Question: Where did the name Switzer originate from?

Question: What did the Alemannic Schwiizer help form the nucleus of?
Passage: The toponym Schwyz itself is first attested in 972, as Old High German Suittes, ultimately perhaps related to suedan "to burn", referring to the area of forest that was burned and cleared to build. The name was extended to the area dominated by the canton, and after the Swabian War of 1499 gradually came to be used for the entire Confederation. The Swiss German name of the country, Schwiiz, is homophonous to that of the canton and the settlement, but distinguished by the use of the definite article (d'Schwiiz for the Confederation, but simply Schwyz for the canton and the town).

Question: In what year was the toponym Schwyz first attested as Old High German Suittes?

Question: At what time did the name Schwyz begin to be used by the entire Confederation?

Question: What was the Swiss German name for Schwyz?

Question: What was the name d'Schwiiz used for?
Passage: The earliest known cultural tribes of the area were members of the Hallstatt and La Tène cultures, named after the archaeological site of La Tène on the north side of Lake Neuchâtel. La Tène culture developed and flourished during the late Iron Age from around 450 BC, possibly under some influence from the Greek and Etruscan civilisations. One of the most important tribal groups in the Swiss region was the Helvetii. Steadily harassed by the Germans, in 58 BC the Helvetii decided to abandon the Swiss plateau and migrate to western Gallia, but Julius Caesar's armies pursued and defeated them at the Battle of Bibracte, in today's western France, forcing the tribe to move back to its original homeland. In 15 BC, Tiberius, who was destined to be the second Roman emperor and his brother, Drusus, conquered the Alps, integrating them into the Roman Empire. The area occupied by the Helvetii—the namesakes of the later Confoederatio Helvetica—first became part of Rome's Gallia Belgica province and then of its Germania Superior province, while the eastern portion of modern Switzerland was integrated into the Roman province of Raetia. Sometime around the start of the Common Era, the Romans maintained a large legionary camp called Vindonissa, now a ruin at the confluence of the Aare and Reuss rivers, near the town of Windisch, an outskirt of Brugg.

Question: What were the two earliest know cultural tribes in Switerland?

Question: Which Swiss cultural tribe developed and flourished during the late Iron Age?

Question: Which Swiss tribal group was defeated by Julius Caesar at the Battle of Bribacti as they tried to escape the Swiss plateau?

Question: In what year did Tiberius conquer the Alps, integrating them into the Roman Empire?

Question: What is the name of the large legionary camp, now a ruin, that the Romans maintained around the start of the Common Era?