Have a deep view into what people are curious about.

🔗 Technology 🔗 Physics 🔗 Physics/Fluid Dynamics

Fluidics, or fluidic logic, is the use of a fluid to perform analog or digital operations similar to those performed with electronics.

The physical basis of fluidics is pneumatics and hydraulics, based on the theoretical foundation of fluid dynamics. The term fluidics is normally used when devices have no moving parts, so ordinary hydraulic components such as hydraulic cylinders and spool valves are not considered or referred to as fluidic devices.

A jet of fluid can be deflected by a weaker jet striking it at the side. This provides nonlinear amplification, similar to the transistor used in electronic digital logic. It is used mostly in environments where electronic digital logic would be unreliable, as in systems exposed to high levels of electromagnetic interference or ionizing radiation.

Nanotechnology considers fluidics as one of its instruments. In this domain, effects such as fluid-solid and fluid-fluid interface forces are often highly significant. Fluidics have also been used for military applications.

🔗 Film

Slaughterbots is a 2017 arms-control advocacy video presenting a dramatized near-future scenario where swarms of inexpensive microdrones use artificial intelligence and facial recognition to assassinate political opponents based on preprogrammed criteria. The video was released onto YouTube by the Future of Life Institute and Stuart Russell, a professor of computer science at Berkeley, on 12 November 2017. The video quickly went viral, gaining over two million views. The video was also screened to the November 2017 United Nations Convention on Certain Conventional Weapons meeting in Geneva.

🔗 Professional sound production 🔗 Record Production 🔗 The Beatles 🔗 Pop music

The Wall of Sound (also called the Spector Sound) is a music production formula developed by American record producer Phil Spector at Gold Star Studios, in the 1960s, with assistance from engineer Larry Levine and the conglomerate of session musicians later known as "the Wrecking Crew". The intention was to exploit the possibilities of studio recording to create an unusually dense orchestral aesthetic that came across well through radios and jukeboxes of the era. Spector explained in 1964: "I was looking for a sound, a sound so strong that if the material was not the greatest, the sound would carry the record. It was a case of augmenting, augmenting. It all fit together like a jigsaw."

A popular misconception holds that the Wall of Sound was created simply through a maximum of noise and distortion, but the method was actually more nuanced. To attain the Wall of Sound, Spector's arrangements called for large ensembles (including some instruments not generally used for ensemble playing, such as electric and acoustic guitars), with multiple instruments doubling or tripling many of the parts to create a fuller, richer tone. For example, Spector often duplicated a part played by an acoustic piano with an electric piano and a harpsichord. Mixed well enough, the three instruments would then be indistinguishable to the listener.

Among other features of the sound, Spector incorporated an array of orchestral instruments (strings, woodwind, brass and percussion) not previously associated with youth-oriented pop music. Reverb from an echo chamber was also highlighted for additional texture. He characterized his methods as "a Wagnerian approach to rock & roll: little symphonies for the kids". The combination of large ensembles with reverberation effects also increased the average audio power in a way that resembles compression. By 1979, the use of compression had become common on the radio, marking the trend that led to the loudness war in the 1980s.

The intricacies of the technique were unprecedented in the field of sound production for popular music. According to Beach Boys leader Brian Wilson, who used the formula extensively: "In the '40s and '50s, arrangements were considered 'OK here, listen to that French horn' or 'listen to this string section now.' It was all a definite sound. There weren't combinations of sound and, with the advent of Phil Spector, we find sound combinations, which—scientifically speaking—is a brilliant aspect of sound production."

🔗 Companies 🔗 Lists 🔗 Disney

The following is a list of assets owned and operated by The Walt Disney Company, unless otherwise indicated.

🔗 Computing

In computer science, the ski rental problem is a name given to a class of problems in which there is a choice between continuing to pay a repeating cost or paying a one-time cost which eliminates or reduces the repeating cost.

🔗 Time 🔗 Christianity

The computus (Latin for 'computation') is a calculation that determines the calendar date of Easter. Easter is traditionally celebrated on the first Sunday after the Paschal full moon, which is the first full moon on or after 21 March (an approximation of the March equinox). Determining this date in advance requires a correlation between the lunar months and the solar year, while also accounting for the month, date, and weekday of the calendar. The calculations produce different results depending on whether the Julian calendar or the Gregorian calendar is used.

In late antiquity, it was feasible for the entire Christian church to receive the date of Easter each year through an annual announcement from the Pope. By the early third century, however, communications had deteriorated to the point that the church put great value in a system that would allow the clergy to independently and consistently determine the date for themselves. Additionally, the church wished to eliminate dependencies on the Hebrew calendar, by deriving Easter directly from the vernal equinox.

In The Reckoning of Time (725), Bede uses computus as a general term for any sort of calculation, although he refers to the Easter cycles of Theophilus as a "Paschal computus." By the end of the 8th century, computus came to refer specifically to the calculation of time.

🔗 Crime 🔗 Organized crime 🔗 Belgium

The Brabant killers, also named the Nijvel Gang in Dutch-speaking media (Dutch: De Bende van Nijvel), and the mad killers of Brabant in French-speaking media (French: Les Tueurs fous du Brabant), are believed to be responsible for a series of violent attacks that mainly occurred in the Belgian province of Brabant between 1982 and 1985. A total of 28 people died and 22 were injured. The actions of the gang, believed to consist of a core of three men, made it Belgium's most notorious unsolved crime spree. The active participants were known as The Giant (a tall man who may have been the leader); the Killer (the main shooter) and the Old Man (a middle aged man who drove). The identities and whereabouts of the "Brabant killers" are unknown. Although significant resources are still dedicated to it, the most recent arrests in the case were of the now-retired original senior detectives. Failure to catch the gang resulted in a parliamentary inquiry. There have been many theories of ulterior motives behind the crimes.

🔗 Disaster management 🔗 Medicine 🔗 China 🔗 Food and drink 🔗 Medicine/Toxicology 🔗 Taiwan

Gutter oil (Chinese: 地沟油; pinyin: dìgōu yóu, or 餿水油; sōushuǐ yóu) is oil which has been recycled from waste oil collected from sources such as restaurant fryers, grease traps, slaughterhouse waste and fatbergs.

Reprocessing of used cooking oil is often very rudimentary; techniques include filtration, boiling, refining, and the removal of some adulterants. It is then packaged and resold as a cheaper alternative to normal cooking oil. Another version of gutter oil uses discarded animal parts, animal fat and skins, internal organs, and expired or otherwise low-quality meat, which is then cooked in large vats in order to extract the oil. Used kitchen oil can be purchased for between $859 and $937 per ton, while the cleaned and refined product can sell for $1,560 per ton. Thus there is great economic incentive to produce and sell gutter oil.

It was estimated in 2011 that up to one in every ten lower-market restaurant meals consumed in China is prepared with recycled oil. As Feng Ping of the China Meat Research Center has said: "The illegal oil shows no difference in appearance and indicators after refining and purification because the law breakers are skillful at coping with the established standards."

Some street vendors and restaurants in China and Taiwan have illegally used recycled oil unfit for human consumption for the purposes of cooking food, leading to a crackdown against such establishments by the Chinese and Taiwanese governments.

Gutter oil is an acceptable raw ingredient for products that are not for human consumption, such as soap, rubber, bio-fuel, and cosmetics.

🔗 Geography 🔗 Antarctica 🔗 Glaciers

A blue iceberg is visible after the ice from above the water melts, causing the smooth portion of ice from below the water to overturn. The rare blue ice is formed from the compression of pure snow, which then develops into glacial ice.

Icebergs may also appear blue due to light refraction and age. Older icebergs reveal vivid hues of green and blue, resulting from a high concentration of color, microorganisms, and compacted ice. One of the better known blue icebergs rests in the waters off Sermilik fjord near Greenland. It is described as an electric blue iceberg and is known to locals as "blue diamond".

🔗 Mathematics 🔗 Statistics 🔗 Systems 🔗 Robotics 🔗 Systems/Control theory

In statistics and control theory, Kalman filtering, also known as linear quadratic estimation (LQE), is an algorithm that uses a series of measurements observed over time, containing statistical noise and other inaccuracies, and produces estimates of unknown variables that tend to be more accurate than those based on a single measurement alone, by estimating a joint probability distribution over the variables for each timeframe. The filter is named after Rudolf E. Kálmán, one of the primary developers of its theory.

The Kalman filter has numerous applications in technology. A common application is for guidance, navigation, and control of vehicles, particularly aircraft, spacecraft and dynamically positioned ships. Furthermore, the Kalman filter is a widely applied concept in time series analysis used in fields such as signal processing and econometrics. Kalman filters also are one of the main topics in the field of robotic motion planning and control and can be used in trajectory optimization. The Kalman filter also works for modeling the central nervous system's control of movement. Due to the time delay between issuing motor commands and receiving sensory feedback, use of the Kalman filter supports a realistic model for making estimates of the current state of the motor system and issuing updated commands.

The algorithm works in a two-step process. In the prediction step, the Kalman filter produces estimates of the current state variables, along with their uncertainties. Once the outcome of the next measurement (necessarily corrupted with some amount of error, including random noise) is observed, these estimates are updated using a weighted average, with more weight being given to estimates with higher certainty. The algorithm is recursive. It can run in real time, using only the present input measurements and the previously calculated state and its uncertainty matrix; no additional past information is required.

Optimality of the Kalman filter assumes that the errors are Gaussian. In the words of Rudolf E. Kálmán: "In summary, the following assumptions are made about random processes: Physical random phenomena may be thought of as due to primary random sources exciting dynamic systems. The primary sources are assumed to be independent gaussian random processes with zero mean; the dynamic systems will be linear." Though regardless of Gaussianity, if the process and measurement covariances are known, the Kalman filter is the best possible linear estimator in the minimum mean-square-error sense.

Extensions and generalizations to the method have also been developed, such as the extended Kalman filter and the unscented Kalman filter which work on nonlinear systems. The underlying model is a hidden Markov model where the state space of the latent variables is continuous and all latent and observed variables have Gaussian distributions. Also, Kalman filter has been successfully used in multi-sensor fusion, and distributed sensor networks to develop distributed or consensus Kalman filter.