Helios

Helios (/ˈhiːli.ɒs/; Ancient Greek: Ἥλιος Hēlios; Latinized as Helius; Ἠέλιος in Homeric Greek) was the personification of the Sun in Greek mythology. He is the son of the Titan Hyperion and the Titaness Theia (Hesiod) (also known as Euryphaessa (Homeric Hymn 31)) and brother of the goddesses Selene, the moon, and Eos, the dawn.

Helios was described as a handsome titan crowned with the shining aureole of the Sun, who drove the chariot of the sun across the sky each day to earth-circling Oceanus and through the world-ocean returned to the East at night. In the Homeric hymn to Helios, Helios is said to drive a golden chariot drawn by steeds (HH 31.14–15); and Pindar speaks of Helios's "fire-darting steeds" (Olympian Ode 7.71). Still later, the horses were given fiery names: Pyrois, Aeos, Aethon, and Phlegon.

As time passed, Helios was increasingly identified with the god of light, Apollo. However, in spite of their syncretism, they were also often viewed as two distinct gods/titan (Helios was a Titan, whereas Apollo was an Olympian). The equivalent of Helios in Roman mythology was Sol, specifically Sol Invictus.

NASA Pathfinder

The NASA Pathfinder and NASA Pathfinder Plus were the first two aircraft developed as part of an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles. AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program. They were built to develop the technologies that would allow long-term, high-altitude aircraft to serve as "atmospheric satellites", to perform atmospheric research tasks as well as serve as communications platforms. They were developed further into the NASA Centurion and NASA Helios aircraft.

Pathfinder

AeroVironment initiated its development of full-scale solar-powered aircraft with the Gossamer Penguin and Solar Challenger vehicles in the late 1970s and early 1980s, following the pioneering work of Robert Boucher, who built the first solar-powered flying models in 1974. Under ERAST, AeroVironment built four generations of long endurance unmanned aerial vehicles (UAVs), the first of which was the Pathfinder.

Helios (lens brand)

Helios (Russian: Ге́лиос) was a brand of camera lenses, made in the USSR. They were usually supplied with Zenit cameras and thus usable with other M42 lens mount cameras such as the Pentax Spotmatic. Some later Helios models were built also for the Pentax K mount.

The Helios-44 and Helios-40 are derivatives of the Carl Zeiss Biotar optical formula. As all lenses based on the Biotar formula, the Helios-44 and Helios-40 produce an unusual "swirly" bokeh effect to the out-of-focus background. The bokeh "circles" become more elliptical in shape as you move away from the center of the photo. This optical phenomenon gives images rendered by these vintage lenses a distinct character, which has created a cult following among fine art photographers.

List of Helios lenses

Footnotes

References

Helix

A helix (pl: helixes or helices) is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helices are coil springs and the handrails of spiral staircases. A "filled-in" helix – for example, a spiral ramp – is called a helicoid. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices. The word helix comes from the Greek word ἕλιξ, "twisted, curved".

Types

Helices can be either right-handed or left-handed. With the line of sight along the helix's axis, if a clockwise screwing motion moves the helix away from the observer, then it is called a right-handed helix; if towards the observer, then it is a left-handed helix. Handedness (or chirality) is a property of the helix, not of the perspective: a right-handed helix cannot be turned to look like a left-handed one unless it is viewed in a mirror, and vice versa.

Helix (disambiguation)

A helix is a spiral-like shape.

Helix may also refer to:

Locations

Earth

Outer space

Art, entertainnent, and media

Comics

Film

Games

Literature

Periodicals

Music

Television

Biology

Computing

Phelix

Phelix is a high-speed stream cipher with a built-in single-pass message authentication code (MAC) functionality, submitted in 2004 to the eSTREAM contest by Doug Whiting, Bruce Schneier, Stefan Lucks, and Frédéric Muller. The cipher uses only the operations of addition modulo 2³², exclusive or, and rotation by a fixed number of bits. Phelix uses a 256-bit key and a 128-bit nonce, claiming a design strength of 128 bits. Concerns have been raised over the ability to recover the secret key if the cipher is used incorrectly.

Performance

Phelix is optimised for 32-bit platforms. The authors state that it can achieve up to eight cycles per byte on modern x86-based processors.

FPGA Hardware performance figures published in the paper "Review of stream cipher candidates from a low resource hardware perspective" are as follows:

Helix

Phelix is a slightly modified form of an earlier cipher, Helix, published in 2003 by Niels Ferguson, Doug Whiting, Bruce Schneier, John Kelsey, Stefan Lucks, and Tadayoshi Kohno; Phelix adds 128 bits to the internal state.