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In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere. Since it is not limited by the curvature of the Earth, skywave propagation can be used to communicate beyond the horizon, at intercontinental distances, it is used in the shortwave frequency bands. As a result of skywave propagation, a signal from a distant AM broadcasting station, a shortwave station, or – during sporadic E propagation conditions a distant VHF FM or TV station – can sometimes be received as as local stations. Most long-distance shortwave radio communication – between 3 and 30 MHz – is a result of skywave propagation. Since the early 1920s amateur radio operators, limited to lower transmitter power than broadcast stations, have taken advantage of skywave for long distance communication. Skywave propagation is distinct from: tropospheric scatter, an alternative method of achieving over-the-horizon transmission at higher frequencies, groundwave propagation, where radio waves travel along Earth's surface without being reflected or refracted by the atmosphere – the dominant propagation mode at lower frequencies, line-of-sight propagation, in which radio waves travel in a straight line, the dominant mode at higher frequencies.

Skywave transmissions can be used for long distance communications by waves directed at a low angle as well as local communications via nearly-vertically directed waves. The ionosphere is a region of the upper atmosphere, from about 80 km to 1000 km in altitude, where neutral air is ionized by solar photons and cosmic rays; when high frequency signals enter the ionosphere at a low angle they are bent back towards the earth by the ionized layer. If the peak ionization is strong enough for the chosen frequency, a wave will exit the bottom of the layer earthwards – as if obliquely reflected from a mirror. Earth's surface reflects the descending wave back up again towards the ionosphere; when operating at frequencies just below the MUF losses can be quite small, so the radio signal may "bounce" or "skip" between the earth and ionosphere two or more times following the curvature of the earth. Signals of only a few Watts can sometimes be received many thousands of miles away; this is. If the ionization is not great enough, the wave only curves downwards, subsequently upwards as the ionization peak is passed so that it exits the top of the layer only displaced.

The wave is lost in space. To prevent this a lower frequency must be chosen. With a single "hop", path distances up to 3500 km may be reached. Longer transmissions can occur with two or more hops. Skywaves directed vertically, or vertically, are called NVIS for "Near-Vertical Incidence". At some frequencies in the lower shortwave region, the high angle skywaves will be reflected directly back towards the ground; when the wave returns to ground it is spread out over a wide area, allowing communications within several hundred miles of the transmitting antenna. NVIS enables local plus regional communications from low-lying valleys, to a large area, for example, an entire state or small country. Coverage of a similar area via a line-of-sight VHF transmitter would require a high mountain top location. NVIS is thus useful for statewide networks, such as those needed for emergency communications. In short wave broadcasting, NVIS is useful for regional broadcasts that are targeted to an area that extends out from the transmitter location to a few hundred miles, such as would be the case in a country or language group to be reached from within the borders of that country.

This will be much more economical than using multiple AM broadcast transmitters. Suitable antennas are designed to produce a strong lobe at high angles; when short range skywave is undesirable, as when an AM broadcaster wishes to avoid interference between the ground wave and sky wave, Anti-fading antennas are used to suppress the waves being propagated at the higher angles. For every distance, from local to maximum distance transmission, there is an optimum "take off" angle for the antenna, as shown here. For example, using the F layer during the night, to best reach a receiver 500 miles away, an antenna should be chosen that has a strong lobe at 40 degrees elevation. One can see that for the longest distances, a lobe at low angles is best. For NVIS, angles above 45 degrees are optimum. Suitable antennas for long distance would be a rhombic. Vertical patterns for each type of antenna are used to select the proper antenna. At any distance sky waves will fade; the layer of ionospheric plasma with sufficient ionization is not fixed, but undulates like the surface of the ocean.

Varying reflection efficiency from this changing surface can cause the reflected signal strength to change, causing "fading" in shortwave broadcasts. More serious fading can occur when signals arrive via two or more paths, for example when both single hop and double hop waves interfere with other, or when a skywave signal and a ground wave signal arrive at about the same strength; this is the most common source of fading with night time AM broadcast signals. Fading is always present with sky wave signals, except for digital signals such as DRM seriou

Scare Campaign

Scare Campaign is a 2016 Australian horror film written and directed by Colin and Cameron Cairnes, starring Meegan Warner, Ian Meadows, Olivia DeJonge and Josh Quong Tart. Scare Campaign is a hidden camera prank show, scaring its targets with old school scares for the last 5 years, their latest target nearly ends up shooting an actress thinking she's a real zombie until the crew reveals to him that it's all on TV. Emma, another actress on the show, speaks to her director and ex-boyfriend Marcus about being more careful who they prank in case they end up scaring "the wrong guy", but Marcus reassures her; that morning, their manager, Vicki shows them a web series called Masked Freaks that involve a bunch of costumed people killing other people gruesomely. The contents of this web series threatens Scare Campaign's popularity and so Vicki encourages the team to up the ante to increase their ratings. Hiring a new and young actress named Abby and the team take their next prank to an abandoned psychiatric hospital where they intend to a prank a new groundskeeper, Rohan.

As the prank goes along as planned, Emma starts having second thoughts about it and leaves Rohan alone, where he explores the asylum through many of the team's special effects, despite Emma's pleas to end the prank. When Abby is signalled to surprise him, Rohan stabs her to death with a letter opener, strangles cameraman Tony and slits the throat of background actress Suze. Emma and special effects specialist J. D. barricade themselves in a room and begs Marcus and camera operator Dick to call the police before Rohan breaks in and kills Marcus and Dick smiles into the camera. Emma and J. D. make it to the van to escape, but J. D. runs back inside to find the keys. Rohan appears in the van, but Emma stabs his hand with a screwdriver into the car seat and runs inside. It's revealed that the whole predicament was a prank and Emma was their new stooge. Trent, the actor playing Rohan, quits. Masked Freaks appear with weapons equipped to their cameras and kills Trent, revealing themselves as actual serial killers and not actors as the web series made it look.

They proceed to murder the other members of Scare Campaign, while Marcus runs back inside after finding Trent dead. He tries to warn Emma, who yells at him and ignores his warning after discovering she was the real stooge of their prank, she believes him and they both run inside and find Suze's body and witness Tony getting killed. Masked Freaks hack into Scare Campaign's computer system and reveal they do what they do for the new generation of online entertainment, they bury Abby alive and give Marcus and Emma five minutes to save her before she runs out of oxygen. Marcus and Emma run out to save Abby and end up killing one of the Masked Freaks, revealed to be a teenager. After saving Abby, the three are surrounded by the Masked Freaks and their boss tells Emma she may leave with either Marcus or Abby, she chooses kisses Marcus before leaving with Abby. While they're driving away, the Masked Freaks reveal to Marcus that Abby was their spy the whole time before wheeling Marcus on a stretcher into a furnace.

On the drive back to town, Emma notices one of the Masked Freaks cameras in the van pointing at her, leaving her to wonder about Abby's involvement. Meegan Warner as Emma Ian Meadows as Marcus Olivia DeJonge as Abby Josh Quong Tart as Trent Patrick Harvey as J. D. Cassandra Magrath as Suze Steve Mouzakis as Tony John Brumpton as George Sigrid Thornton as Vicki Kaiting Yap as Ayako Jason Geary as Dick Andrew L. Urban at gave a positive review, writing "Propelled by an ever-inventive screenplay, Scare Campaign revels in surprising us while scaring us. To its credit, we don't see the twists coming, the Russian Doll-type structure gives the film a rich texture." Scare Campaign at the Internet Movie Database

Dannie Heineman

Dannie N. Heineman was a Belgian-American engineer and businessman, he was the managing director and controlling shareholder of the Belgian industrial multinational Sofina. He was a prolific sponsor of science through Heineman Foundation in medical sciences and awards in mathematical physics and astrophysics. In 1939, while living in Belgium, Dannie Heineman managed to get the Luxembourg government to open its closed borders and admit 100 Jewish families from Germany; the persuasive argument was that hotels in Luxembourg were empty and he would pay for the rooms and give the Jews an allowance, they would not be working and taking jobs away from Luxembourg workers. This arrangement worked until 10 May 1940. At that point his assistant Mr. Schmidt made a final six months payment to the families. Among the families was the physicist Ernst Ising who survived the war. Dannie-Heineman Prize of the Göttingen Academy of Sciences and Humanities Dannie Heineman Prize for Mathematical Physics Dannie Heineman Prize for Astrophysics Biography at American Physical Society Another biography

Sundara Kanda

Sundara Kaanda, is the fifth book in the Hindu epic, the Ramayana. The original Sundara Kanda is in Sanskrit and was composed by Valmiki, the first to scripturally record the Ramayana. Sundara Kanda is the only chapter of the Ramayana, but rather Hanuman; the work depicts the adventures of Hanuman and his selflessness and devotion to Rama are emphasized in the text. Hanuman was fondly called “Sundara” by his mother Anjani and Sage Valmiki chose this name over others as the Sundara Kanda is about Hanuman's journey to Lanka; the Sundara Kanda forms the heart of Valmiki's Ramayana and consists of a detailed, vivid account of Hanuman's adventures. After learning about Sita, Hanuman assumes a gargantuan form and makes a colossal leap across the ocean to Lanka after defeating Surasa, the Mother of the Nagas and Sinhika, sent by the Devtas. In Lanka, Hanuman hears Rama's chant from Vibhishana. Vibhishana recognizes Hanuman as a devoted Ram Bhakt. From Vibhishana, Hanuman comes to know location of Sita in Ashok Vatika.

In the Ashok Vatika, Sita is wooed and threatened by Ravana and his demon mistresses to marry Ravana. Hanuman reassures her, he offers to carry Sita back to Rama, however she refuses, reluctant to allow herself to be rescued by any one, other than her husband. She says that Rama himself must avenge the insult of her abduction. Hanuman wreaks havoc in Lanka by destroying trees and buildings, killing Ravana's warriors, he allows himself to be produced before Ravana. He gives a bold lecture to Ravana to release Sita, he is condemned and his tail is set on fire, but he escapes his bonds and, leaping from roof to roof, sets fire to Ravana's citadel and makes the giant leap back from the island. The joyous search party returns to Kishkindha with the news, it is traditional to begin the reading of the Ramayana with the Sundara Kanda. This lesson is recited by religious Hindus, preferably on Tuesdays or Saturdays, these days having been earmarked for special prayers to Hanuman, it happens to be for nullification of the malefic effects of the crow mounted, the son of Surya and Chhaya, Lord Shani.

Ramayana reveals that Shani Dev, captive at Ravana's palace, was rescued by Lord Hanuman. As a token of thanks, Shani Dev offered reprieve to all devotees of Lord Hanuman. Alternately once Shani Dev was caught between Hanuman's shoulders and the ceiling when attempting to mount the latter to influence his stars. Unable to bear the pain, Shani Dev offered gratitude in return to an immediate release; the religious faith suggests. Many Hindus believe that if one does not have time to read the whole Ramayana, one should read the Sundara Kanda. Multiple variations of the Sundara Kanda exist in other languages as well, for instance in Awadhi, the language in which the saint Tulsidas wrote the Ramacharitamanas; the Sri Ramacharitamanas was written much than Valmiki's Ramayana, in the 16th century. An earlier Tamil version, Ramavataram, by Kambar is a prevalent text among the Sri Vaishnava and Smartha Brahmins in South India. Ranganatha Ramayanam a Telugu version of valmiki Ramayan written by Gona Budha Reddy described well.

M. S. Ramarao wrote Telugu version for Hanuman Chalisa of Tulsidas and Sundara kanda of Valmiki Ramayana as'Sundarakandamu' in Telugu during 1972-74, he sang Sundarakanda in the form of Telugu songs. Hanuman Chalisa is a different poetic contribution towards the heroics of Hanuman by the poet, Tulasidas. Though it mentions his achievements during Ramayana, it goes beyond that as well, encompassing the complete life of Hanuman. Shodasi: Secrets of the Ramayana by Seshendra Sharma Reviews: The Beauty of Beauty: An Aesthetic Journey Into The Ramayana Vedanta Spiritual Library - Sundara Kãnda: Hanuman's Odyssey in English verse Vedanta Spiritual Library - Sundara Kandam Sundara Kandam in Hindi Sundara Kanda in English rhyme with original text

Verne Heavy Anti-Aircraft Battery

Verne Heavy Anti-Aircraft Battery is a World War II anti-aircraft battery on the Isle of Portland, England. It is located on private property in the north-east area of the island, south of the Verne Citadel; the battery became a scheduled monument in March 2019. During World War II, Portland's naval base was a primary target for German air raids, prompting a number of heavy anti-aircraft batteries to be built within the region, one of, located close to the Verne Citadel. Locally designated as "Battery B", other nearby batteries included examples at Blackhead near Weymouth, Barrow Hill near Southwell, Chickerell, Weymouth; the Verne battery's operated using QF 3.7-inch AA guns. Manned by personnel of AA Command, the battery's associated Gun Operations Room was based at Red Barracks and from 1941 at Nottington House, Weymouth; the battery was fitted with GL Mark II radar from 1942. After the war, the battery survived and was put into use as stables

Murray Two Dam

Murray Two Dam or Murray 2 Dam is a major ungated concrete arch dam with a controlled spillway across Khancoban Bank, a diverted flow of the Snowy and Geehi rivers in the Snowy Mountains region of New South Wales, Australia. The impounded reservoir is called the Murray Two Murray 2 Pondage; the structure was completed by Thiess Brothers in 1968, is one of the sixteen major dams that comprise the Snowy Mountains Scheme, a vast hydroelectricity and irrigation complex constructed in south-east Australia between 1949 and 1974, now run by Snowy Hydro. Murray Two Dam is a major dam, located within the Snowy Valleys local government area 5 kilometres southeast of the town of Khancoban; the dam was constructed by a consortium including Thiess Bros Pty Limited and Dillingham Corporation based on engineering plans developed under contract from the Snowy Mountains Hydroelectric Authority. The arch dam wall comprises 19,500 cubic metres of concrete and is 43 metres high and 131 metres long. At 100% capacity the dam wall holds back 2,344 megalitres of water.

The surface area of Murray Two Pondage is 190 hectares and the catchment area is 53 square kilometres. The controlled spillway is capable of discharging 566 cubic metres per second. Located upstream of the Murray Two Pondage is the Murray 1 Power Station, a 950 megawatts conventional hydroelectric power station. Murray 1 draws the supply of its water under pressure from an 11.8 kilometres Haupt-tunnel, with a diameter of 6.93 metres, lined along its length. Meanwhile, located downstream is the Murray 2 Power Station, a 550 megawatts conventional hydroelectric power station. Water from the power plant is discharged into the reservoir, before passing over the spillway of Khancoban Dam, down the Swampy Plain River. Kosciuszko National Park List of dams and reservoirs in New South Wales Snowy Hydro Limited Snowy Mountains Scheme Snowy Scheme Museum Bevitt, R.. "Expert panel environmental flow assessment of various rivers affected by the Snowy Mountains Scheme". NSW Department of Water and Energy. ISBN 978-0-7347-5656-5