Isochronous and anisochronous are characteristics, while synchronous and asynchronous are relationships.
|
|
As a result, isochronous cyclotrons became more popular in the research field.
|
|
FireWire is capable of safely operating critical systems due to the way multiple devices interact with the bus and how the bus allocates bandwidth to the devices. FireWire is capable of both asynchronous and isochronous transfer methods at once. Isochronous data transfers are transfers for devices that require continuous, guaranteed bandwidth. In an aircraft, for instance, isochronous devices include control of the rudder, mouse operations and data from pressure sensors outside the aircraft.
|
|
Research Nuclear reactor WWR-M, Cyclotron U-120, Isochronous cyclotron U-240, 10 MeV Electrostatic Tandem Accelerator.
|
|
All these elements require constant, uninterrupted bandwidth. To support both elements, FireWire dedicates a certain percentage to isochronous data and the rest to asynchronous data. In IEEE 1394, 80% of the bus is reserved for isochronous cycles, leaving asynchronous data with a minimum of 20% of the bus.
|
|
An alternative to the synchrocyclotron is the isochronous cyclotron, which has a magnetic field that increases with radius, rather than with time. Isochronous cyclotrons are capable of producing much greater beam current than synchrocyclotrons, but require azimuthal variations in the field strength to provide a strong focusing effect and keep the particles captured in their spiral trajectory. For this reason, an isochronous cyclotron is also called an "AVF (azimuthal varying field) cyclotron". This solution for focusing the particle beam was proposed by L. H. Thomas in 1938.
|
|
In telecommunication, an isochronous signal is a signal in which the time interval separating any two significant instants is equal to the unit interval or a multiple of the unit interval. Variations in the time intervals are constrained within specified limits. "Isochronous" is a characteristic of one signal, while "synchronous" indicates a relationship between two or more signals.
|
|
The electromechanical oscillator was originally designed as a source of isochronous (that is to say, frequency stable), alternating electric current used with both wireless transmitting and receiving apparatus. In dynamical system theory an oscillator is called isochronous if the frequency is independent of its amplitude. An electromechanical device runs at the same rate regardless of changes in its drive force, so it maintains a constant frequency (hz).
|
|
The advantage of the isochronous cyclotron is that it can deliver continuous beams of higher average intensity, which is useful for some applications. The main disadvantages are the size and cost of the large magnet needed, and the difficulty in achieving the high magnetic field values required at the outer edge of the structure. Synchrocyclotrons have not been built since the isochronous cyclotron was developed.
|
|
On unprivileged use (i.e. non-root user) of sched_setscheduler called with a request for realtime policy class, the scheduler will demote the task to Isochronous policy.
|
|
The stepping pace, sometimes itself called an "amble," is a slightly uneven lateral gait, with a non-isochronous 1-2, 3-4 sequence, while the singlefoot has an isochronous, even 1-2-3-4 rhythm. The stepping pace is faster than a running walk and extremely smooth, but not as energy-efficient.Howe, p. 34 It is a smooth gait at slower speeds, but when sped up can turn into a 2-beat pace.
|
|
After the node is finished, the remaining nodes take turns in order. This repeats until all the devices have used their portion of the 125 microseconds, with isochronous transfers having priority.
|
|
The second approach to the problem of accelerating relativistic particles is the isochronous cyclotron. In such a structure, the accelerating field's frequency (and the cyclotron resonance frequency) is kept constant for all energies by shaping the magnet poles so to increase magnetic field with radius. Thus, all particles get accelerated in isochronous time intervals. Higher energy particles travel a shorter distance in each orbit than they would in a classical cyclotron, thus remaining in phase with the accelerating field.
|
|
If these variations in the escapement's force cause changes in the pendulum's width of swing (amplitude), this will cause corresponding slight changes in the period, since (as discussed at top) a pendulum with a finite swing is not quite isochronous. Therefore, the goal of traditional escapement design is to apply the force with the proper profile, and at the correct point in the pendulum's cycle, so force variations have no effect on the pendulum's amplitude. This is called an isochronous escapement.
|
|
Tasks with higher scheduling priorities get executed first. Tasks are ordered (or distributed) and chosen based on the virtual deadline formula in all policies except for the realtime and Isochronous priority classes. The execution behavior is still a weighted variation of the Round-Robin Scheduler especially when tasks have the same priority below the Isochronous policy. The user tuneable round robin interval (time slice) is 6 milliseconds by default which was chosen as the minimal jitter just below detectable by humans.
|
|
Fixed-Field Alternating Gradient accelerators (FFA)s, in which a magnetic field which is fixed in time, but with a radial variation to achieve strong focusing, allows the beam to be accelerated with a high repetition rate but in a much smaller radial spread than in the cyclotron case. Isochronous FFAs, like isochronous cyclotrons, achieve continuous beam operation, but without the need for a huge dipole bending magnet covering the entire radius of the orbits. Some new developments in FFAs are covered in.
|
|
Tennessee Walking Horse at the running walk Lateral gaits fall in the sequence right hind, right front, left hind, left front. They can be distinguished by whether the footfall rhythm is "even" or isochronous, four equal beats in a 1-2-3-4 rhythm; or non-isochronous, a slightly uneven 1-2, 3-4 rhythm created because the horse picks up and sets down its feet on each individual side slightly faster, creating a slight pause when switching to the opposite lateral pair of footfalls.
|
|
Domestic Digital Bus, D2B, is an isochronous ring-based fibreoptical communications technology, with a bandwidth of 12 Mbit/s, specified by the Optical Chip Consortium for use in automotive applications. As of 2007, D2B is used by Mercedes-Benz in their vehicles.
|
|
The rate of error increases with amplitude, so when limited to small swings of a few degrees the pendulum is nearly isochronous; its period is independent of changes in amplitude. Therefore, the swing of the pendulum in clocks is limited to 2° to 4°.
|
|
One distinction is whether the footfall rhythm is isochronous, four equal beats in a 1-2-3-4 rhythm; or a non-isochronous 1-2, 3-4 rhythm created by a slight pause between the groundstrike of the forefoot of one side to the rear of the other. Many breeds of horses inherit the ability to perform these gaits, which may be observable naturally from birth or may present with a minimal amount of training. Some horses without apparent inborn gaited ability can be taught to "gait" or amble. However, training usually is not successful unless there is some inherited genetic ability in the horse.
|
|
Isochronous accelerators have no longitudinal beam focusing, but this is not a strong limitation in accelerators with rapid ramp rates typically used in FFA designs. The major disadvantages include the fact that VFFAs requires unusual magnet designs and currently VFFA designs have only been simulated rather than tested.
|
|
Galileo claimed that a simple pendulum is isochronous, i.e. that its swings always take the same amount of time, independently of the amplitude. In fact, this is only approximately true, as was discovered by Christiaan Huygens. Galileo also found that the square of the period varies directly with the length of the pendulum.
|
|
Chapter 4: Well Backstripping and Subsidence Analysis in Gravity Anomalies, Flexure and the Thermo-Mechanical Evolution of the West Iberia Margin and its Conjugate of Newfoundland (2008), PhD Thesis by Tiago Cunha It is a method by which successive layers of basin fill sediment are "stripped off" the total stratigraphy during analysis of that basin's history. In a typical scenario, a sedimentary basin deepens away from a marginal flexure, and the accompanying isochronous strata typically thicken basinward. By isolating the isochronous packages one-by-one, these can be "peeled off" or backstripped - and the lower bounding surface rotated upward to a datum. By successively backstripping isochrons, the basin's deepening history can be plotted in reverse, leading to clues as to its tectonic or isostatic origin.
|
|
The main drawback of this device is that, as a result of the variation in the frequency of the oscillating voltage supply, only a very small fraction of the ions leaving the source are captured in phase-stable orbits of maximum radius and energy with the result that the output beam current has a low duty cycle, and the average beam current is only a small fraction of the instantaneous beam current. Thus the machine produces high energy ions, though with comparatively low intensity. The next development step of the cyclotron concept, the isochronous cyclotron, maintains a constant RF driving frequency and compensates for relativistic effects by increasing the magnetic field with radius. Isochronous cyclotrons are capable of producing much greater beam current than synchrocyclotrons.
|
|
If accelerated further, the beam would continue to spiral outward to a larger radius but the particles would no longer gain enough speed to complete the larger circle in step with the accelerating RF. To accommodate relativistic effects the magnetic field needs to be increased to higher radii as is done in isochronous cyclotrons. An example of an isochronous cyclotron is the PSI Ring cyclotron in Switzerland, which provides protons at the energy of 590 MeV which corresponds to roughly 80% of the speed of light. The advantage of such a cyclotron is the maximum achievable extracted proton current which is currently 2.2 mA. The energy and current correspond to 1.3 MW beam power which is the highest of any accelerator currently existing.
|
|
With the invention in 1879 of the light bulb, that changed too. The isochronous clock changed lives. Appointments are rarely "within the hour," but at quarter hours (and being five minutes late is often considered being tardy). People often eat, drink, sleep, and even go to the bathroom in adherence to some time-dependent schedule.
|
|
The subclass descriptor is used to declare a device bootable. A boot device meets a minimum adherence to a basic protocol and will be recognized by a computer's BIOS. Each USB HID interface communicates with the host using either a control pipe or an interrupt pipe. Isochronous and bulk pipes are not used in HID class devices.
|
|
Cyclotron building Isochronous cyclotron U-120M is the primary experimental facility of the institute and it is the only cyclotron in the Czech Republic. It has been operating since 1977. The cyclotron is used both for fundamental research and applications. It can accelerate ions within the range of the mass-to-charge ratio A/q = 1 - 2.8.
|
|
IEEE 1394 is an interface standard for a serial bus for high-speed communications and isochronous real-time data transfer. It was developed in the late 1980s and early 1990s by Apple in cooperation with a number of companies, primarily Sony and Panasonic. Apple called the interface FireWire. It is also known by the brands i.
|
|
The mLAN protocol was originally developed by Yamaha Corporation, and publicly introduced in January 2000. It was available under a royalty-free license to anyone interested in utilizing the technology. mLAN exploits several features of the IEEE 1394 (FireWire) standard such as isochronous transfer and intelligent connection management. There are two versions of the mLAN protocol.
|
|
In 2003 the first specification of Profinet IO (IO = Input Output) was published. The application interface of the Profibus DP (DP = Decentralized Periphery), which was successful on the market, was adopted and supplemented with current protocols from the Internet. In the following year, the extension with isochronous transmission follows, which makes Profinet IO suitable for motion control applications.
|
|
Mathematical Masterpieces: Further Chronicles by the Explorers. (Springer), p. 169. "The cycloid had already occupied the minds of great mathematicians and scientists such as Galileo, Torricelli, Mersenne, Roberval, Fermat, Descartes, Pascal, and others [18], yet none of them discovered its isochronous property." The tautochrone problem, the attempt to identify this curve, was solved by Christiaan Huygens in 1659.
|
|
Another cause of varying driving force is friction, which varies as the lubricating oil ages. Early watchmakers empirically found approaches to make their balance springs isochronous. For example, John Arnold in 1776 patented a helical (cylindrical) form of the balance spring, in which the ends of the spring were coiled inwards. In 1861 M. Phillips published a theoretical treatment of the problem.
|
|
This allows particles to be accelerated continuously, on every period of the radio frequency (RF), rather than in bursts as in most other accelerator types. This principle that alternating field gradients have a net focusing effect is called strong focusing. It was obscurely known theoretically long before it was put into practice. Examples of isochronous cyclotrons abound; in fact almost all modern cyclotrons use azimuthally-varying fields.
|
|
In serial communication, clock synchronization can refer to clock recovery which achieves frequency synchronization, as opposed to full phase synchronization. Such clock synchronization is used in synchronization in telecommunications and automatic baud rate detection. Plesiochronous or isochronous operation refers to a system with frequency synchronization and loose constraints on phase synchronization. Synchronous operation implies a tighter synchronization based on time perhaps in addition to frequency.
|
|
For the functionalities of Conformance Class C (CC-C) the Isochronous Real-Time (IRT) protocol is mainly used. With the bandwidth reservation, a part of the available transmission bandwidth of 100 MBit/s is reserved exclusively for real-time tasks. A procedure similar to a time multiplexing method is used. The bandwidth is divided into fixed cycle times, which in turn are divided into phases.
|
|
In telecommunication, a distributed-queue dual-bus network (DQDB) is a distributed multi-access network that (a) supports integrated communications using a dual bus and distributed queuing, (b) provides access to local or metropolitan area networks, and (c) supports connectionless data transfer, connection-oriented data transfer, and isochronous communications, such as voice communications. IEEE 802.6 is an example of a network providing DQDB access methods.
|
|
But the clocks were still aligned with the local noonday sun. Following the invention of the locomotive in 1830, time had to be synchronized across vast distances in order to organize the train schedules. This eventually led to the development of time zones, and, thus, global isochronous time. These time changes were not accepted everywhere right away, because many people's lives were still tied closely to the length of the daytime.
|
|
Information on the SLIMbus DATA line is allocated to Control Space and Data Space channels. The Control Space carries bus configuration and synchronization information as well as inter-Device Message communication. The Control Space may be dynamically programmed to take as much of the SLIMbus bandwidth as required, even up to 100% at times. Data Space, when present, carries application-specific information such as isochronous and asynchronous data streams.
|
|
Another solution is UsbDk. UsbDk supports all device types including isochronous and provides simpler way for device access acquisition that does not involve INF files creation and installation. UsbDk is open source, community supported and works on all Windows versions starting from Windows XP. If the previous solutions are inappropriate, one can write a custom driver. For newer versions of Microsoft Windows, it can be done using the Windows Driver Foundation.
|
|
Pierre Le Roy (1717–1785) was a French clockmaker. He was the inventor of the detent escapement, the temperature-compensated balance and the isochronous balance spring. His developments are considered as the foundation of the modern precision clock. Le Roy was born in Paris, eldest son of Julien Le Roy, a clockmaker to Louis XV who had worked with Henry Sully,Encyclopedia of time Samuel L. Macey p.
|
|
Team of British archeologists were also involved in the archeological dig. Stratigraphic coring results confirmed the presence of seven cultural layers. By 1980 the site was fully explored. Neolithic Chavdar Culture, polychromatic and anthropomorphic pottery, 6200-5400 B.C., Bulgaria Early Neolithic village of Chavdar is isochronous to Karanovo I and II Neolithic sites which are dated about 6200 BC. The artifact findings are also similar to Kremikovtsi Neolithic village findings.
|
|
"...it is affected by either the intemperance of the air or any faults in the mechanism so the crutch QR is not always activated by the same force... With large arcs the swings take longer, in the way I have explained, therefore some inequalities in the motion of the timepiece exist from this cause...", , translation by Ernest L. Edwardes (December 1970) Antiquarian Horology, Vol.7, No.1 To make its period isochronous, Huygens mounted cycloidal-shaped metal 'chops' next to the pivots in his clocks, that constrained the suspension cord and forced the pendulum to follow a cycloid arc (see cycloidal pendulum).Andrewes, W.J.H. Clocks and Watches: The leap to precision in This solution didn't prove as practical as simply limiting the pendulum's swing to small angles of a few degrees. The realization that only small swings were isochronous motivated the development of the anchor escapement around 1670, which reduced the pendulum swing in clocks to 4°–6°.
|
|
Specific benefits of FOUNDATION technology include: reduced wiring, multi- variables from a single multi-channel field instrument, simpler integration and easier maintenance. Using Half Duplex RS485 hardware connection a two wire communication is possible. The FOUNDATION Fieldbus H1 has support for Intrinsically Safe Wiring. Unlike other protocols, FOUNDATION H1 provides explicit synchronization of control and communication for precisely periodic (isochronous) communication and execution of control functions with minimized dead time and jitter.
|
|
Apollonius ( 200 BC) discussed evolutes in Book V of his Conics. However, Huygens is sometimes credited with being the first to study them (1673). Huygens formulated his theory of evolutes sometime around 1659 to help solve the problem of finding the tautochrone curve, which in turn helped him construct an isochronous pendulum. This was because the tautochrone curve is a cycloid, and the cycloid has the unique property that its evolute is also a cycloid.
|
|
Launch Time is a new concept for handling Ethernet packets proposed for the Linux kernel. It is an attempt to add some isochronous capability to the kernel by hinting at what time a packet should be sent out. When sending a packet to socket, an additional bit (MSG_LAUNCHTIME) is specified in the "sendto" flags field. If this bit is set, then the buffer passed to the socket includes the desired send time or "launch time".
|
|
Again, the procedure is the same as experiments one and two but the key difference is that they used an atonal melody for these participants to listen to. Lilach’s and her associates conducted two experiments. In the first experiment, eight undergraduate students were selected who had no musical training at all. They listened to pairs of isochronous tone sequences while simultaneously doing a task to see how accurate they were at completing the task.
|
|
MOST150 was introduced in October 2007 and provides a physical layer to implement Ethernet in automobiles. It increases the frame length up to 3072 bits, which is about 6 times the bandwidth of MOST25. It also integrates an Ethernet channel with adjustable bandwidth in addition to the three established channels (control message channel, streaming data channel, packet data channel) of the other grades of MOST. MOST150 also permits isochronous transfer on the synchronous channel.
|
|
Both acceptable gaits are lateral, having four beats and is performed in a lateral sequence — left hind, left fore, right hind, right fore. The Peruvian Horse can also canter, will trot and pace at liberty, and do a natural relaxed walk. The Peruvian Paso performs two variations of the four-beat gait. The first, the paso llano, is isochronous, meaning that there are four equal beats in a 1-2-3-4 rhythm.
|
|
Galileo was the first to investigate the timekeeping properties of pendulums, beginning around 1602.His interest was sparked by his discovery that, at least for small swings, the pendulum is isochronous; its period of swing is the same for different size swings. He realized that this property made the pendulum useful for timekeeping. He also discovered that the pendulum's period is dependent on its length, and independent of the mass of the pendulum bob.
|
|
The degree of isochronous distortion, in data transmission, is the ratio of the absolute value of the maximum measured difference between the actual and the theoretical intervals separating any two significant instants of modulation (or demodulation), to the unit interval. These instants are not necessarily consecutive. This value is usually expressed as a percentage. The result of the measurement should be qualified by an indication if the period, usually limited, of the observation.
|
|
M. Phillips, "Sur le spiral reglant", Paris, 1861. He demonstrated that a balance spring whose center of gravity coincides with the axis of the balance wheel is isochronous. In general practice, the most common method of achieving isochronism is through the use of the Breguet overcoil, which places part of the outermost turn of the hairspring in a different plane from the rest of the spring. This allows the hairspring to "breathe" more evenly and symmetrically.
|
|
Since the Rindler chart is a coordinate chart for Minkowski spacetime, we expect to find ten linearly independent Killing vector fields. Indeed, in the Cartesian chart we can readily find ten linearly independent Killing vector fields, generating respectively one parameter subgroups of time translation, three spatials, three rotations and three boosts. Together these generate the (proper isochronous) Poincaré group, the symmetry group of Minkowski spacetime. However, it is instructive to write down and solve the Killing vector equations directly.
|
|
The escape wheel must have an odd number of teeth for the escapement to function. With an even number, two opposing teeth will contact the pallets at the same time, jamming the escapement. The usual angle between the pallets was 90° to 105°, resulting in a foliot or pendulum swing of around 80° to 100°. In order to reduce the pendulum's swing to make it more isochronous, the French used larger pallet angles, upward of 115°.
|
|
With invention of the pendulum clock in 1656 by Christiaan Huygens, came isochronous time, with a fixed pace of 3600 seconds per hour. By 1680, both a minute hand and then a second hand were added. Some of the first of these had a separate dial for the minute hand (turning counter-clockwise), and a second hand that took 5 minutes per cycle. Even as late as 1773, towns were content to order clocks without minute hands.
|
|
1394a is capable of arbitration accelerations, allowing the bus to accelerate arbitration cycles to improve efficiency. It also allows for arbitrated short bus reset, in which a node can be added or dropped without causing a big drop in isochronous transmission. 1394a also standardized the 4-conductor alpha connector developed by Sony and trademarked as "i.LINK", already widely in use on consumer devices such as camcorders, most PC laptops, a number of PC desktops, and other small FireWire devices.
|
|
Beat induction is the process in which a regular isochronous pulse is activated while one listens to music (i.e. the beat to which one would tap one's foot). It was thought that the cognitive mechanism that allows us to infer a beat from a sound pattern, and to synchronize or dance to it, was uniquely human. No primate tested so far—with exception of the human species—can dance or collaboratively clap to the beat of the music.
|
|
It uses multiple task runqueues in some configurations one runqueue per CPU, whereas its predecessor BFS only used one task runqueue for all CPUs. Tasks are ordered as a gradient in the skip list in a way that realtime policy priority comes first and idle policy priority comes last. Normal and idle priority policy still get sorted by virtual deadline which uses nice values. Realtime and Isochronous policy tasks are run in FIFO order ignoring nice values.
|
|
Schematic of a cycloidal pendulum. If a simple pendulum is suspended from the cusp of an inverted cycloid, such that the "string" is constrained between the adjacent arcs of the cycloid, and the pendulum's length L is equal to that of half the arc length of the cycloid (i.e., twice the diameter of the generating circle, L=4r), the bob of the pendulum also traces a cycloid path. Such a cycloidal pendulum is isochronous, regardless of amplitude.
|
|
FireWire is a serial bus, meaning that information is transferred one bit at a time. Parallel buses utilize a number of different physical connections, and as such are usually more costly and typically heavier. IEEE 1394 fully supports both isochronous and asynchronous applications. Apple intended FireWire to be a serial replacement for the parallel SCSI bus, while providing connectivity for digital audio and video equipment. Apple's development began in the late 1980s, later presented to the IEEE, and was completed in January 1995.
|
|
A tautochrone or isochrone curve is the curve for which the time taken by an object sliding without friction in uniform gravity to its lowest point is independent of its starting point. The curve is a cycloid, and the time is equal to π times the square root of the radius over the acceleration of gravity. Christiaan Huygens was the first to discover the tautochronous property (or isochronous property) of the cycloid.Knoebel, Arthur; Laubenbacher, Reinhard; Lodder, Jerry; Pengelley, David (2007).
|
|
A problem throughout the history of spring-driven clocks and watches is that the force (torque) provided by a spring is not constant, but diminishes as the spring unwinds (see graph). However, timepieces have to run at a constant rate in order to keep accurate time. Timekeeping mechanisms are never perfectly isochronous, meaning their rate is affected by changes in the drive force. This was especially true of the primitive verge and foliot type used before the advent of the balance spring in 1657.
|
|
A balance spring obeys Hooke's Law: the restoring torque is proportional to the angular displacement. When this property is exactly satisfied, the balance spring is said to be isochronous, and the period of oscillation is independent of the amplitude of oscillation. This is an essential property for accurate timekeeping, because no mechanical drive train can provide absolutely constant driving force. This is particularly true in watches and portable clocks which are powered by a mainspring, which provides a diminishing drive force as it unwinds.
|
|
This watch, it seems, has not survived. The final form of balance spring arrangement used by Tompion was a plain spiral with a single balance, indeed the same arrangement employed by Christiaan Huygens in watches made for him by Thuret. A few of Tompion's early spiral balance spring movements were also of a similar specification to the Huygens/Thuret pattern as they had a standing barrel and no fusee. Huygens imagined that the latter would not be necessary as the spiral spring would render the balance isochronous.
|
|
The Logical Link Control and Adaptation Protocol (L2CAP) is used to multiplex multiple logical connections between two devices using different higher level protocols. Provides segmentation and reassembly of on-air packets. In Basic mode, L2CAP provides packets with a payload configurable up to 64 kB, with 672 bytes as the default MTU, and 48 bytes as the minimum mandatory supported MTU. In Retransmission and Flow Control modes, L2CAP can be configured either for isochronous data or reliable data per channel by performing retransmissions and CRC checks.
|
|
Engineers designed various types of hydraulic or pneumatic pump regulator to overcome the limitations of Watt's governor. Automatic variable expansion-gear attachment to a Corliss engine (1878) Marie-Joseph Farcot designed a governor in 1854, and he and Joseph designed several others after this, including the crossed-arm governor, which achieved close to isochronous operation, although it was prone to instability. The Farcots refined the design with friction brakes, and in 1864 added an air dashpot. They obtained a patent for a spring- loaded governor in 1864.
|
|
After having designed plans in 1754, he constructed his first chronometers by 1756, and accomplished his masterpiece in 1766. This remarkable chronometer incorporated a detached escapement, a temperature- compensated balance and an isochronous balance spring, innovations which would be adopted in subsequent chronometers. Harrison demonstrated a reliable chronometer at sea, but these developments by Le Roy are considered by Rupert Gould to be the foundation of the modern chronometer. Pierre Le Roy's chronometer had a performance equivalent to that of the Harrison H4 chronometer.
|
|
In 1673, 17 years after he invented the pendulum clock, Christiaan Huygens published his theory of the pendulum, Horologium Oscillatorium sive de motu pendulorum.The constellation of Horologium was later named in honor of this book. Marin Mersenne and René Descartes had discovered around 1636 that the pendulum was not quite isochronous; its period increased somewhat with its amplitude. Huygens analyzed this problem by determining what curve an object must follow to descend by gravity to the same point in the same time interval, regardless of starting point; the so-called tautochrone curve.
|
|
It was this that led him to adopt circular balances in the Third Sea Clock (H3). The Board granted him another £500, and while waiting for the war to end, he proceeded to work on H3. Harrison spent seventeen years working on this third 'sea clock', but despite every effort it did not perform exactly as he would have wished. The problem was that, because Harrison did not fully understand the physics behind the springs used to control the balance wheels, the timing of the wheels was not isochronous, a characteristic that affected its accuracy.
|
|
The realization that only small pendulum swings were nearly isochronous motivated clockmakers to design escapements with small swings. The chief advantage of the anchor was that by locating the pallets farther from the pivot, the swing of the pendulum was reduced from around 100° in verge clocks to only 4°-6°. In addition to the improved accuracy due to isochronism, this allowed clocks to use longer pendulums, which had a slower 'beat'. Lower air drag meant they needed less power to keep swinging, and caused less wear on the clock's movement.
|
|
Windows XP includes FireWire 800 support (1394b) beginning with Service Pack 1.[Performance of 1394 devices may decrease after you install Windows XP Service Pack 2] As mentioned in the above section, Windows XP includes improved support for FireWire cameras and audio video devices. S/PDIF audio and MPEG-2 video streams are supported across FireWire from audio video receivers or set-top boxes, DVD or D-VHS, speakers, or TV transmissions. Windows XP supports the AV/C (IEC 61883 protocol for isochronous real-time data transfer for audio-video applications.
|
|
This means the engine driving the generator supplying one of the sources generally must be controlled by an isochronous governor. It is generally required that the closed transition, or overlap time, be less than 100 milliseconds. If either source is not present or not acceptable (such as when normal power fails) the switch must operate in a break-before-make mode (standard open transition operation) to ensure no backfeeding occurs. Closed transition transfer makes code-mandated monthly testing less objectionable because it eliminates the interruption to critical loads which occurs during traditional open transition transfer.
|
|
LIO Firewire Target for Mac OS X The FireWire SBP-2 fabric module enables Linux to export local storage devices via IEEE 1394, so that other systems can mount them as an ordinary IEEE 1394 storage device. IEEE 1394 is a serial bus interface standard for high-speed communications and isochronous real-time data transfer. It was developed by Apple as "FireWire" in the late 1980s and early 1990s, and Macintosh computers have supported "FireWire target disk mode" since 1999. The FireWire SBP-2 fabric module was released with Linux 3.5 on July 21, 2012.
|
|
Laacher See Tephra: A widespread isochronous late Quaternary tephra layer in central and northern Europe. Geological Society of America Bulletin 96 (12), pp. 1554–1571 At Niederbieber the pumice layer measured approximately 1m in thickness under which several scatters of burned and unburned artefacts were encountered. Extensive excavations of an area almost covering 1000m2 were conducted between 1981 and 1988 and again between 1996 and 1999 by MONREPOS Archaeological Research Centre and Museum for Human Behavioural Evolution of the Romano-Germanic-Centralmuseum Mainz and the State Office for Preservation of Historical Monuments Coblence.
|
|
In most stability studies, real-time or accelerated, a few units of the reference material are tested at intervals. If the measurement system used for testing the materials is not perfectly stable, this can generate imprecise data or can be mistaken for instability of the material. To overcome these difficulties, it is often possible to move RM units, at intervals, to some reference temperature where they remain stable, and then test all the accumulated units - which have undergone different exposure times - at the same time. This is referred to as an isochronous study.
|
|
By geometrical methods which were an early use of calculus, he showed it to be a cycloid, rather than the circular arc of a pendulum's bob, and therefore that pendulums are not isochronous. He also solved a problem posed by Mersenne: how to calculate the period of a pendulum made of an arbitrarily-shaped swinging rigid body. This involved discovering the centre of oscillation and its reciprocal relationship with the pivot point. In the same work, he analysed the conical pendulum, consisting of a weight on a cord moving in a circle, using the concept of centrifugal force.
|
|
Jost Bürgi invented the cross-beat escapement in 1584, a variation of the verge escapement which had two foliots which rotated in opposite directions."Jost Burgi" in According to contemporary accounts, his clocks achieved remarkable accuracy of within a minute per day, two orders of magnitude better than other clocks of the time. However, this improvement was probably not due to the escapement itself, but rather to better workmanship and his invention of the remontoire, a device which isolated the escapement from changes in drive force. Without a balance spring, the crossbeat would have been no more isochronous than the verge.
|
|
Vertical Orbit Excursion FFAs (VFFAs) are a special type of FFA arranged so that higher energy orbits occur above (or below) lower energy orbits, rather than radially outward. This is accomplished with skew-focusing fields that push particles with higher beam rigidity vertically into regions with a higher dipole field. The major advantage offered by a VFFA design over a FFA design is that the path-length is held constant between particles with different energies and therefore relativistic particles travel isochronously. Isochronicity of the revolution period enables continuous beam operation, therefore offering the same advantage in power that isochronous cyclotrons have over synchrocyclotrons.
|
|
In 1769, after his chronometre underwent testing aboard the corvette Aurore, he was awarded the double prize offered by the Académie française for the best method of measuring time at sea. He succeeded in giving his instruments the greatest possible regularity by the discovery of the isochronous spiral spring, in which he was in competition with Ferdinand Berthoud, but which he published first. He was the author of several valuable publications on the art and science of clock-making and chronography, among them the Étrennes chronométriques of 1760. He also became Horloger du Roi in 1760.
|
|
The classical cyclotron is therefore only capable of accelerating particles up to a few percent of the speed of light. To accommodate increased mass the magnetic field may be modified by appropriately shaping the pole pieces as in the isochronous cyclotrons, operating in a pulsed mode and changing the frequency applied to the dees as in the synchrocyclotrons, either of which is limited by the diminishing cost effectiveness of making larger machines. Cost limitations have been overcome by employing the more complex synchrotron or modern, klystron-driven linear accelerators, both of which have the advantage of scalability, offering more power within an improved cost structure as the machines are made larger.
|
|
ATM and Frame Relay, for example, are both examples of a connection-oriented, unreliable data link layer protocols. There are also reliable connectionless protocols as well, such as AX.25 network layer protocol, when it passes data in I-frames. But this combination is rare, and reliable-connectionless is uncommon in modern networks. Connection-oriented protocols handle real-time traffic substantially more efficiently than connectionless protocols, especially with short constant length packets, which is why ATM has yet to be replaced with Ethernet for carrying real-time, isochronous traffic streams, especially in heavily aggregated networks like backbones, where the motto "bandwidth is cheap" fails to deliver on its promise.
|
|
The anchor was the second widely used escapement in Europe, replacing the primitive 400-year-old verge escapement in pendulum clocks. The pendulums in verge escapement clocks had very wide swings of 80° to 100°. In 1673, seventeen years after he invented the pendulum clock, Christiaan Huygens published his mathematical analysis of pendulums, Horologium Oscillatorium. In it he showed that the wide pendulum swings of verge clocks caused them to be inaccurate, because the period of oscillation of the pendulum was not isochronous but varied to a small degree due to circular error with changes in the amplitude of the pendulum's swing, which occurred with unavoidable changes in drive force.
|
|
The second pendulum clock built around 1673 by Christiaan Huygens, inventor of the pendulum clock. Drawing is from his treatise Horologium Oscillatorium, published 1673, Paris, and it records improvements to the mechanism that Huygens had illustrated in the 1658 publication of his invention, titled Horologium. It is a weight-driven clock (the weight chain is removed) with a verge escapement (K,L), with the 1 second pendulum (X) suspended on a cord (V). The large metal plate (T) in front of the pendulum cord is the first illustration of Huygens' 'cycloidal cheeks', an attempt to improve accuracy by forcing the pendulum to follow a cycloidal path, making its swing isochronous.
|
|
The perceived harmony (consonance) of two such notes would be explained if the ratio of the air oscillation frequencies is also 1 : 2, which in turn is consistent with the source-air-motion-frequency-equivalence hypothesis. He also performed extensive experiments to determine the acceleration of falling objects by comparing them with the swing of pendulums, reported in his Cogitata Physico-Mathematica in 1644. He was the first to measure the length of the seconds pendulum, that is a pendulum whose swing takes one second, and the first to observe that a pendulum's swings are not isochronous as Galileo thought, but that large swings take longer than small swings.
|
|
The synchrotron evolved from the cyclotron, the first cyclic particle accelerator. While a classical cyclotron uses both a constant guiding magnetic field and a constant-frequency electromagnetic field (and is working in classical approximation), its successor, the isochronous cyclotron, works by local variations of the guiding magnetic field, adapting the increasing relativistic mass of particles during acceleration. A drawing of the Cosmotron In a synchrotron, this adaptation is done by variation of the magnetic field strength in time, rather than in space. For particles that are not close to the speed of light, the frequency of the applied electromagnetic field may also change to follow their non-constant circulation time.
|
|
One partial countermeasure against simple power attacks, but not differential power-analysis attacks, is to design the software so that it is "PC-secure" in the "program counter security model". In a PC-secure program, the execution path does not depend on secret values. In other words, all conditional branches depend only on public information. (This is a more restrictive condition than isochronous code, but a less restrictive condition than branch-free code.) Even though multiply operations draw more power than NOP on practically all CPUs, using a constant execution path prevents such operation-dependent power differences (differences in power from choosing one branch over another) from leaking any secret information.
|
|
AES47 has been developed to allow the simultaneous transport and switched distribution of a large number of AES3 linear audio streams at different sample frequencies. AES47 can support any of the standard AES3 sample rates and word size. AES11 Annex D (the November 2005 printing or version of AES11-2003) shows an example method to provide isochronous timing relationships for distributed AES3 structures over asynchronous networks such as AES47 where reference signals may be locked to common timing sources such as GPS. AES53 specifies how timing markers within AES47 can be used to associate an absolute time stamp with individual audio samples as described in AES47 Amendment 1.
|
|
429 He also differed from Harrison regarding his temperature compensation method, which used the variation of the rotation radius of the balance by modifying the diameter of the balance through bi-metallic components, a method which would become a standard in chronometers. His technique for temperature compensation was highly efficient in that it worked without changing the length of the spiral balance spring, which he had discovered to be isochronous only at a precise given length (i.e. when frequency is independent of amplitude, so that a mechanical clock or watch runs at the same rate regardless of changes in its drive force, so it keeps correct time as the mainspring unwinds).
|
|
Spring-driven pendulum clock, designed by Huygens, built by instrument maker Salomon Coster (1657), and a copy of the Horologium Oscillatorium. Museum Boerhaave, Leiden In 1673 Huygens published Horologium Oscillatorium sive de motu pendulorum, his major work on pendulums and horology. It had been observed by Mersenne and others that pendulums are not quite isochronous: their period depends on their width of swing, with wide swings taking slightly longer than narrow swings.Marin Mersenne 1647 Reflectiones Physico-Mathematicae, Paris, Chapter 19, cited in Huygens analyzed this problem by finding the curve down which a mass will slide under the influence of gravity in the same amount of time, regardless of its starting point; the so-called tautochrone problem.
|
|
The Younger Dryas impact hypothesis or Clovis comet hypothesis posits that fragments of a large (more than 4 kilometers in diameter), disintegrating asteroid or comet struck North America, South America, Europe, and western Asia about 12,800 years ago. Multiple airbursts/impacts produced the Younger Dryas (YD) boundary layer (YDB), depositing peak concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds, forming an isochronous datum at more than 50 sites across about 50 million km² of Earth’s surface. Some scientists have proposed that this event triggered extensive biomass burning, a brief impact winter and the Younger Dryas abrupt climate change, contributed to extinctions of late Pleistocene megafauna, and resulted in the end of the Clovis culture.
|
|
To accommodate the wide pendulum swings caused by the verge escapement, "wings" have been added on the sides Grandfather clock These early clocks, due to their verge escapements, had wide pendulum swings of 80–100°. In his 1673 analysis of pendulums, Horologium Oscillatorium, Huygens showed that wide swings made the pendulum inaccurate, causing its period, and thus the rate of the clock, to vary with unavoidable variations in the driving force provided by the movement. Clockmakers' realization that only pendulums with small swings of a few degrees are isochronous motivated the invention of the anchor escapement by Robert Hooke around 1658, which reduced the pendulum's swing to 4–6°. The anchor became the standard escapement used in pendulum clocks.
|
|
Remontoires are used because the timekeeping mechanism in clocks and watches, the pendulum or balance wheel, is never isochronous; its rate is affected by changes in the drive force applied to it. In spring-driven timepieces, the drive force declines as the mainspring runs down. In weight-driven clocks the drive force, provided by a weight suspended by a cord, is more constant, but imperfections in the gear train and variations in lubrication also cause small variations. In turret clocks, the large hands, which are attached to the clock's wheel train, are exposed to the weather on the outside of the tower, so winds and accumulations of ice and snow apply disturbing forces to the hands, which are passed on to the wheel train.
|
|
By a complicated method that was an early use of calculus, he showed this curve was a cycloid, rather than the circular arc of a pendulum,Huygens, Horologium Oscillatorium, Part 2, Proposition 25 confirming that the pendulum was not isochronous and Galileo's observation of isochronism was accurate only for small swings. Huygens also solved the problem of how to calculate the period of an arbitrarily shaped pendulum (called a compound pendulum), discovering the center of oscillation, and its interchangeability with the pivot point. gives a detailed description of Huygen's methods The existing clock movement, the verge escapement, made pendulums swing in very wide arcs of about 100°. Huygens showed this was a source of inaccuracy, causing the period to vary with amplitude changes caused by small unavoidable variations in the clock's drive force.
|
|
Tephra horizons in Iceland Marker horizons, chronohorizons, key beds or marker beds are stratigraphic units of the same age and of such distinctive composition and appearance, that, despite their presence in separate geographic locations, there is no doubt about their being of equivalent age (isochronous) and of common origin. Such clear markers facilitate the correlation of strata, and used in conjunction with fossil floral and faunal assemblages and paleomagnetism, permit the mapping of land masses and bodies of water throughout the history of the earth. They usually consist of a relatively thin layer of sedimentary rock that is readily recognized on the basis of either its distinct physical characteristics or fossil content and can be mapped over a very large geographic area.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, J.A., eds.
|
|
AES11 Annex D (in the November 2005 or later printing or version) shows an example method to provide isochronous timing relationships for distributed AES3 structures over asynchronous networks such as AES47 where reference signals may be locked to common timing sources such as GPS. In addition, the Audio Engineering Society has now published a related standard called AES53, that specifies how the timing markers already specified in AES47 may be used to associate an absolute time- stamp with individual audio samples. This may be closely associated with AES11 and used to provide a way of aligning streams from disparate sources, including synchronizing audio to video in networked structures. The media profile defined in annex A of AES67 provides a means of using AES11 synchronization via the Precision Time Protocol.
|
|
A bioevent or bio-event (a shortening of 'biotic event' or 'biological event') is an event recognised in a sequence of sedimentary rocks, where there is a significant change in the biota as recorded by assemblages of fossils over a relatively short period of time. It has been defined as "short-term (hours or days to kyrs) locally, regionally, or interregionally pervasive changes in the ecological, biogeographical, and/or evolutionary character of biotas that are isochronous or nearly so throughout their range". Bioevents either relate to diversification of a particular fossil group or a reduction, these may equate to speciation events or extinction events, or may only represent migration. Records of the appearance and disappearance of particular taxa at a single locality are insufficient to define a bioevent.
|
|
On architectures where the instruction execution time is not data-dependent, a PC-secure program is also immune to timing attacks."The Program Counter Security Model: Automatic Detection and Removal of Control-Flow Side Channel Attacks" by David Molnar, Matt Piotrowski, David Schultz, David Wagner (2005)."The Program Counter Security Model: Automatic Detection and Removal of Control-Flow Side Channel Attacks" USENIX Work-in-Progress presentation of paper Another way in which code can be non-isochronous is that modern CPUs have a memory cache: accessing infrequently used information incurs a large timing penalty, revealing some information about the frequency of use of memory blocks. Cryptographic code designed to resist cache attacks attempts to use memory in only a predictable fashion (such as accessing only the input, outputs and program data, and doing so according to a fixed pattern).
|
|
In the research article “Memory for musical tones: the impact of tonality and the creation of false memories” , Dominique Vuvan and her researchers did three experiments that are focused on music memory specifically single tones with a tonal melodic condition. The result of the first experiment revealed that the responses of test subjects that listened to isochronous tones revealed quality remembrance in expected and unexpected targets in major tonal context compared to moderately expected targets. Vuvan's second experiment used minor melodies that hindered tonal anticipation due to how minor tonality can simultaneously be presented in three forms. The final experiment used atonal melodies that showed how participants were struggling to decipher each musical tone due to the absence of tonal structure. Lilach’s research, along with her colleagues, aimed to experiment on how working memory fully functions when combining memorized music information.
|
|
Animation of anchor escapement Invented around 1657 by Robert Hooke, the anchor (see animation to the right) quickly superseded the verge to become the standard escapement used in pendulum clocks through the 19th century. Its advantage was that it reduced the wide pendulum swing angles of the verge to 3–6°, making the pendulum nearly isochronous, and allowing the use of longer, slower-moving pendulums, which used less energy. The anchor is responsible for the long narrow shape of most pendulum clocks, and for the development of the grandfather clock, the first anchor clock to be sold commercially, which was invented around 1680 by William Clement, who disputed credit for the escapement with Hooke. The escapement increased the accuracy of pendulum clocks to such a degree that the minute hand was added to the clock face in the late 1600s (before this, clocks had only an hour hand).
|
|
Another countermeasure under the first category is to use security analysis software to identify certain classes of side channel attacks that can be found during the design stages of the underlying hardware itself. Timing attacks and cache attacks are both identifiable through certain commercially available security analysis software platforms, which allow for testing to identify the attack vulnerability itself, as well as the effectiveness of the architectural change to circumvent the vulnerability. The most comprehensive method to employ this countermeasure is to create a Secure Development Lifecycle for hardware, which includes utilizing all available security analysis platforms at their respective stages of the hardware development lifecycle. In the case of timing attacks against targets whose computation times are quantized into discrete clock cycle counts, an effective countermeasure against is to design the software to be isochronous, that is to run in an exactly constant amount of time, independently of secret values.
|
|
Clockmakers discovered in the 1700s that for accuracy, the best place to apply the impulse to keep the pendulum swinging was at the bottom of its swing, as it passes through its equilibrium position. If the impulse is applied during the pendulum's downswing, before it reaches the bottom, the impulse force tends to decrease the period of the swing, so an increase in drive force causes the clock to gain time. If the impulse is applied during the pendulum's upswing, after it reaches the bottom, the impulse force tends to increase the period of the swing, so an increase in drive force causes the clock to lose time. In 1826 British astronomer George Airy proved this; specifically he proved that a pendulum that is driven by a drive impulse that is symmetrical about its bottom equilibrium position is isochronous for different drive forces, ignoring friction, and that the deadbeat escapement approximately satisfies this condition.
|
|