Study investigates craters formed by raindrops w Video

first_img Explore further (PhysOrg.com) — Hiroaki Katsuragi and a team from Kyushu University in Fukuoka, Japan, have been investigating what happens when water drops of various sizes are allowed to fall from a height of 10 to 480 mm onto a granular target consisting of grains of silicon carbide with grain sizes ranging from four to 50 microns. They used a laser system to measure the radius and depth of each crater. They discovered the water drops, all approximately 4.8 mm in diameter, result in cylindrical craters under certain conditions. The results may help scientists interpret possible signs of water on other planets and in fossils, apparently of raindrops on Earth.Katsuragi found that low-speed impacts on small grains did not compress the grains on the surface immediately but created 1.5 mm deep cylindrical craters (dubbed “sink craters”) as the drops slowly compressed the fluffy grains beneath. Craters were much shallower when the grain size was larger.High-speed impacts compressed the grains immediately on impact, and there was no further compression. This produced a convex “bump” higher than the original surface, and this resulted in an inner ring. Katsuragi suggested grains are collected in the initial impact and then as the drop spreads out they are dropped in the center when the water sinks. Medium speed drops made less impact on the surface than either low or high speed drops. Physicists Develop Force Law for Granular Impacts: Sand, Other Granular Matter’s Behavior Is Better Defined © 2010 PhysOrg.com A drop of water hits a bed of grains. (see video below) More information: Hiroaki Katsuragi, Morphology Scaling of Drop Impact onto a Granular Layer, Phys. Rev. Lett. 104, 218001 (2010) DOI:10.1103/PhysRevLett.104.218001 PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen Play A 4.8-millimeter-diameter drop of water hits a bed of 4-micron-diameter grains after being dropped from a height of 160 millimeters. Video: Hiroaki Katsuragi / Kyushu University (via APS Focus) Katsuragi also derived a mathematical formula to fit the experimental data and hence predict the radius of an impact crater from the density of the granular material used for the target surface. He discovered the crater’s radius is approximately proportional to both the ratio of grain density to water density and to a constant known as the Weber number, which numerically describes the relationship between the inertial force and the surface tension force. Dense grains make the water drops deform more on impact and the result is a larger crater. Drops with a higher Weber number (larger or faster drops) are likely to break apart on impact, reducing the size of the crater.There have been many studies of hard objects hitting soft granular targets, and these have produced craters much like those seen on the moon and other moons in the Solar System, but there have been few studies of the impact of liquid drops on granular surfaces. A number of fossilized depressions believed to be fossils of craters left by raindrops have been found, and the present study may help scientists confirm that the depressions were made by raindrops.The results are published in Physical Review Letters. Citation: Study investigates craters formed by raindrops (w/ Video) (2010, June 1) retrieved 18 August 2019 from https://phys.org/news/2010-06-craters-raindrops-video.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

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Habitat is designed to provide stay on the moon sleeps two

first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Choi said the team came up with the idea of a “flexible divider inside the pod that can be moved to cordon off the area where astronauts remove their suits from where they sleep.” The proposed system has the potential to double the reachable distance from the lunar base, increasing the reachable area by a factor of four.Choi in Popular Science summarized the components in their design: It is made up of “an inflatable pod that sleeps two; a reflective shield to prevent the sun’s rays from roasting explorers; life support systems on the rover that will supply oxygen, water and food, maintain the habitat’s temperature, scrub out carbon dioxide, and remove excess humidity; and a flexible roll-out solar array to supply the shelter’s power and recharge the rover’s batteries.”MIT’s Samuel Schreiner, one of the study’s authors, said in Popular Science that the system, when packed, takes up about half as much space as an average refrigerator. Journal information: Acta Astronautica “The system is intended to enable two astronauts, exploring with an unpressurized rover, to remove their spacesuits for an 8-hr rest away from the lunar base and then conduct a second day of surface exploration before returning to base,” they wrote.They noted how lunar surface exploration systems will need to evolve from a system designed for short-term sorties to a system that can support longer durations. That goal is what they have in mind; they presented their conceptual design, they said, in the context of next-generation lunar exploration. The authors said their system will enable two astronauts to conduct a full day of lunar surface exploration, sleep and recover within the inflatable habitat at a location away from the lunar base and then conduct a second day of exploration before returning to the base. More information: An overnight habitat for expanding lunar surface exploration, Acta Astronautica, Volume 112, July–August 2015, Pages 158–170. DOI: 10.1016/j.actaastro.2015.03.012AbstractThis paper presents the conceptual design and analysis of a system intended to increase the range, scientific capability, and safety of manned lunar surface exploration, requiring only a modest increase in capability over the Apollo mission designs. The system is intended to enable two astronauts, exploring with an unpressurized rover, to remove their space suits for an 8-h rest away from the lunar base and then conduct a second day of surface exploration before returning to base. This system is composed of an Environmental Control and Life Support System on the rover, an inflatable habitat, a solar shield and a solar power array. The proposed system doubles the distance reachable from the lunar base, thus increasing the area available for science and exploration by a factor of four. In addition to increasing mission capability, the proposed system also increases fault tolerance with an emergency inflatable structure and additional consumables to mitigate a wide range of suit or rover failures. The mass, volume, and power analyses of each subsystem are integrated to generate a total system mass of 124 kg and a volume of 594 L, both of which can be accommodated on the Apollo Lunar Roving Vehicle with minor improvements. (Phys.org)—People have felt the excitement of seeing their courageous space heroes embark from the Earth to the moon. Those same heroes went up because, beyond completing the journey, they hoped to—in one word— explore. That has been a problem, said Charles Q. Choi in Popular Science, who referred to the limitations in “hang time.” He wrote, “The Apollo program landed a dozen men there from 1969 to 1972, but they spent a total of only three days and six hours actually walking the surface. That’s because they couldn’t stray from their lunar lander and its life support.”Now a team of researchers have devised a way to extend a stay and extend the explorers’ reach beyond the lunar lander. The answer is in packable, inflatable tents. The astronauts could stray from the lunar lander to spend more time on the actual surface of the moon. The team wrote that, “Instead of returning to base, the astronauts would then enter the habitat, doff their suits,and prepare for a second day of lunar exploration (eat,sleep,hygiene,etc.).”Boing Boing said that the researchers designed a pill-shaped inflatable moon tent that sleeps two. The tent fills with oxygen. Their paper, which is available online, details their work, and is titled, “An overnight habitat for expanding lunar surface exploration,” in Acta Astronautica.The authors are from MIT (Department of Aeronautics and Astronautics) and from Brown (Department of Geological Sciences). © 2015 Phys.org A cutaway view of the operational system in its deployed state. The inflatable habitat (1) provides an overnight shelter in which two astronauts can sleep, while the Environmental Control and Life Support System on the rover (2) maintains the habitat internal environment. The thermal shield (3) mitigates solar radiation, and a solar array (4) supplies power. Credit: Acta Astronautica, Volume 112, July–August 2015, Pages 158–170. doi:10.1016/j.actaastro.2015.03.012 Explore further As such, this is more than a sleeping tent; it is a sustaining habitat. As Boing Boing said, it is a system that protects explorers from the sun’s rays and it helps to keep out moon dust from sleeping quarters. Moon dust can be dangerous. Popular Science said it collects on an astronaut’s suit. “The dust is electrostatically charged and sticks to everything, the way a rubbed balloon attracts lint. It is also dangerous, each grain similar to a shard of glass.” Choi in Popular Science said that lunar dust can cause skin and eye irritation and corrosion. When inhaled, it can possibly cause lower-airway issues. Europe’s plans to visit the Moon in 2018 The concept of operations for entering the habitat with inflatable ribs and the flexible membrane airlock. This novel concept allows the internal volume to be used as both an airlock and a habitat. Credit: Acta Astronautica, Volume 112, July–August 2015, Pages 158–170. doi:10.1016/j.actaastro.2015.03.012 Citation: Habitat is designed to provide stay on the moon, sleeps two (2015, June 16) retrieved 18 August 2019 from https://phys.org/news/2015-06-habitat-moon.html The inflatable design with the optimized geometry that minimized mass and packing volume while satisfying minimum human living space requirements. Credit: Acta Astronautica, Volume 112, July–August 2015, Pages 158–170. doi:10.1016/j.actaastro.2015.03.012last_img read more

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Mayak the crowd funded Russian satellite nearing launch

first_img © 2016 Tech Xplore Russian engineers working on the Mayak crowd funded satellite project have announced that the satellite is nearing a launch date—once in space, the team claims that it will be the most visible object in the night sky. The project has been instigated by engineers and others with the University of Mechanical Engineering in Moscow. The team reported that they had collected a million and a half rubles (approximately USD 20,000) via the Boomstarter crowd-funding site which has been added to other donations—together, it has been enough to build and test the satellite.The project has three main goals, the first is to prove that such an effort can work, i.e. that crowd-funding can be used to pay for space research projects. The team wants to show that space exploration is no longer confined to just governments or wealthy groups or individuals—and that going forward, most any group or person with a passion for space exploration can start a project and get it funded. The second goal is for the satellite to do its job, which is to unfurl and use its large swath of reflectors to reflect rays from the sun back to Earth—which will make it the brightest object in the night sky. Mayak was designed and built at UME. The third goal, which requires further funding, is to build an aerodynamic braking system for satellites that can be used to bring them back down to Earth, removing the need to add an engine. As a side project, the team also has plans to build a model of the Mayak satellite to be housed in Moscow’s Museum of Cosmonautics.As with other crowd-funding projects, interested donors were given several options, from donating as little as 300 rubles (USD 5) to 2,500, to 300,000 (USD 4,000). Giving more money meant gaining more access to the project and the people working on it, with the top group receiving an invitation to watch the launch on-site. The team notes that like other satellite projects, users who wish to do so will be able to follow the path of the satellite using a smart phone application. The team has also announced that its partner, the Russian Space launch company, Roscosmos, has confirmed that Mayak may be aboard a Soyuz-2 rocket as early as the middle of this year. Citation: Mayak, the crowd funded Russian satellite nearing launch (2016, March 1) retrieved 18 August 2019 from https://phys.org/news/2016-03-mayak-crowd-funded-russian-satellite.html Explore further Students to build a third space debris observation satellite This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

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When inspiration comes from a nightie

In an attempt to touch the human heart, Spandan, a solo exhibition of  artist Sangeeta Singh attempts to  celebrate thoughts in various forms and shapes. ‘Art for me is a visual statement of the celebration of thoughts in form and content. The objects which has intrigued me in the past have involved simplest of things that we overlook in our daily lives.The sense of human migration that seeps in when you look at rickshaw pullers to the essence of faithfulness in our lives which comes best in the form of a loyal dog or a pet to the sense of freedom that flows from the uninhibited birds. Also Read – ‘Playing Jojo was emotionally exhausting’All these thoughts inspired me to bring them alive with my creations by chanelising them,’ said Sangeeta.The exhibition is a collection of more than 30 ensembles, like oil on canvas, some drawings on paper and an installation. The artist says she mostly uses oil on canvas and also does a few sketches with ink and acrylics.She attributes her art to her mentor Rameshwar Broota under whom she honed her skills.‘My exhibition Spandan is a word in Sanskrit which means heartbeat and my concept is to touch the heart. I have painted different themes ranging from rickshawallas and their shadows, games people play, the hustle bustle of urban life depicted by birds. In one of the paintings I used a pink nightie as a metaphor of femininity,’ added Sangeeta. Also Read – Leslie doing new comedy special with NetflixFor her paintings, she seeks inspiration from everyday life. ‘Inspiration comes in many forms. It is often from the world around or any incident, which triggers my mind or a behavioural pattern which intrigues me. I am a keen observer. When I interact with people I observe their behavior rather than looks. My paintings are more  about feelings of the subject. Form is secondary. I use my instincts and intuition to decide the subjects.Like in the series of bags and birds, the used bag was lying in my room for over a week as I was quite fascinated by its form. One day as I picked it up to dispose it I clicked over two dozen photos of the bag and during the process of studying those pictures I could just relate to it and used them in my works. Showing them with energy bursting in yellow and red colors.The birds moving out of the bag is just a portrayal of the inner chaos and how we are moving in a busy world,’ said Sangeeta.DETAILAt: Visual Arts Gallery, India Habitat Center, Lodhi Road On Till: 1 To 7 October  Timings: 11am To 8 Pm read more

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City gallery gives a spin to printmaking

first_imgWith several shows on printmaking doing the rounds this season, this highly technical process that needs great patience, skill and competence, surely seems to be in vogue. But when some of the most renowned printmakers experiment even within this complex medium by adding drawings on their limited edition prints, the show has to be special.The ongoing show at Art Perspective — Lasting Impressions — is a unique one, where  artists were asked to perform a new experiment with their prints. Director Suruchi Saraf says that she ‘wanted to add an exciting element’ to printmaking. ‘What better than blending this beautiful medium with drawings. While the basic print remains the same for each limited edition, it’s the different drawing that’s done on each of them which makes each print one single edition,’ she says. Also Read – ‘Playing Jojo was emotionally exhausting’And the artists are no less elated at having stretched their imagination. Says Dattatraya Apte: ‘Adding a different drawing on each print created a different setting for the visual narrative. The garden of Garhi has become a part of my daily life and the crows, squirrels, leaves, flowers, stone pathways, earthen bowls with water, curtains, all played their role in building the narrative through these drawings,’ says the artist.Jayanti Rabadia’s work based on ‘sayings’ or Also Read – Leslie doing new comedy special with Netflixkahavatein reiterates their strength through different forms of animals, birds along with human figures. ‘For this portfolio of 10 prints with drawings, I have chosen the Dashavatar from the Indian mythology. Each work speaks of their heroic achievements,’ she says. For KR Subbanna, the same motifs of human and animal form find place on his canvas but ‘drawing fantasized floral motifs on these prints has been a unique experience.’Artist RB Bhaskaran echoes the same sentiment when he says: ‘When it comes to traditional print making and their limited editions, the accepted code is to have a number of limited editions, and then the cancellation of the original plate but when Art Perspective thought of this experimental idea of printing an edition and then also drawing around each of the print, and that too not with identical drawings, it was a challenge for me. It took more time to do the drawing than the printing itself. I have enjoyed this experiment as it is all free hand drawing allowing your imagination to free flowly.’ Shail Choyal says: ‘An episode from Bhagvatpuran where Krishna plays the divine flute and the resonance mesmerises the cows to return home is the basis of my work. The imagery of the cow has been my most favourite motif for the last one decade and I have loved to paint, etch and sculpt the cow in its various moods — and aimed to project a dramatic tension through juxtaposition of the allegorical with the real. Use of landscape through pencil drawings around the flute player is neither religious nor historical but sensuous and other worldly. The drama in the episode here may look absurd and ironic but, I certainly aim to balance the ironic and the absurd with the nostalgia I confront in everyday life.’Siddharth portrays a folktale from Punjab of how practice makes man perfect. The story is that of a man who carries his cow on his shoulders when it was very young and light. Every day he does the same till he could carry the cow even she was older and heavy. The artist says: ‘I made the drawing and the gallery took the initiative to get the etching prints done from a professional printmaker. Later, I started building images around the print with different permutation and combinations. It was a great experience and very experimental exercise.’Go catch this show!last_img read more

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A saree affair

first_imgSo here is your chance ladies! An exhibition by Delhi Craft Council titled Sarees of India – ‘Innovating Tradition’ is on in the Capital.The three-day exhibition brings together weavers from all corners of the country. Weavers from Odisha, West Bengal, Assam and Banaras and other states will be displaying their creations at this event. The exhibition focuses on novel techniques and new ideas re-inventing the traditional weaves and prints.‘This year we will exhibit the work of 20 participants bringing numerous types of sarees. The range of textiles includes chanderi, chikankari, linen, khadi, South Indian weaves, prints, kantha, bandhani, ikat, tussar prints,  laharia and more,’ said Purnima Rai, president, Delhi Crafts Council. Also Read – ‘Playing Jojo was emotionally exhausting’The artistes have brought their specialities and personal touches to their work through interesting textures, bright and bold hues.A hint of modernity with traditional bandhani with unique contemporary designs on tussar silk is what artiste Suleman Khatri plays to display. Pracheen is showcasing the fine art of hand block printing and dyeing in vegetable colours.Delhi Craft Council will also present their annual award ‘Sutrakar Samman’ to Bhanu Murthy- a weaver from Tamil Nadu who specialise in traditional weaving of the region.last_img read more

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The essence of her

first_imgThe Capital is going to see an art exhibition The Opening Show of the Novice where artist Astha Mittal had put her thoughts on the canvas miffed by the state of women in the society. She dedicates the show to all the woman who share a unconditional relationship with the society and its tradition. The artist who is an engineering graduate with an advertising degree finds art very liberating and peaceful and so she translates her thoughts into an expression on canvas.  Also Read – ‘Playing Jojo was emotionally exhausting’Observing her surroundings, Mittal has used her experience to portray the way women are seen in society today. Mittal uses a mix of acrylic and oil on wood of figurative abstracts. She says, ‘Painting is a strong medium and  I have tried learning it on my own over the years. In this particular body of work, I have wished to showcase an essence of ‘her’ which is never spoken of or lost in oblivion because of social customs and practices. It is the woman who is always questioned about her traditions, customs and the so-called societal obligations. Even being an educated, well travelled, exposed to different cultures one is tied down to follow our customary nonsensical traditions, apparently only meant for women.My art depicts that apathy of a woman and how she fights for her freedom of thoughts, beliefs each day’. Mittal who gets inspired by her mother adds, ‘The main inspiration behind this work is my mother who is an epitome of patience, love and perseverance’.last_img read more

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Ornaments worth Rs 12L stolen

first_imgKolkata: Miscreants looted ornaments worth nearly Rs 12 lakh from a jewellery shop in Goyalpara area of Ichhapur in North 24-Parganas on the Monday night.A gang of around 7-8 miscreants entered a shop by breaking open the shutter and looted valuables and hard cash from there. Locals on Tuesday morning found the shutter broken and reported the matter to the local police. The owner of jewellery shop, Abhijit Mukherjee was also informed by the police. When the police entered the jewellery shop, they found everything was ransacked. Also Read – Heavy rain hits traffic, flightsMukherjee who rushed to the spot immediately after being informed, told the police that there were many orders of ornaments, especially ahead of the Bengali new year. The ornaments that have been stolen were kept inside the chest. He informed police that there were valuables worth nearly Rs 12 lakh. The investigation has become a little difficult for the police as the CCTV camera was broken by the miscreants. They also removed the hard disc of the surveillance camera. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedAccording to preliminary investigation, police suspect that the miscreants had prior information that worthy valuables were there at the shop which were supposed to be delivered to the customers on or before the Bengali New Year. Locals on Tuesday morning raised questions on the security in the area. They also questioned on how the miscreants entered the jewellery shop by breaking open the shutter as it is situated in a middle of a market place.According to preliminary investigation, police suspect that there were 7-8 miscreants in the gang who came in a car. Police have started a detailed probe into the incident. They are interrogating the employees of the jewelley shop in this connection. Raids are being conducted to nab the culprits.last_img read more

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Mamata calls for steps to bring down ATC loss below 10 percent

first_imgKolkata: Chief Minister Mamata Banerjee has called for necessary steps to bring down the Aggregate Technical and Commercial (ATC) loss, that the state Power department incurs, to below 10 percent.The Chief Minister held a review meeting to take stock of the power sector in the state. Sobhandeb Chattopadhyay, the state Power minister, along with senior officials of the department, was present in the meeting.Banerjee has also set up a committee headed by Chief Secretary Malay De. The committee will look into the steps needed to be taken to bring down the ATC loss. It will be holding review meetings every month. At present, the ATC loss stands at 28 percent and the Chief Minister has directed to bring it below 10 percent. Sources said that the Chief Minister had discussed about the issue in details with the state Power minister and the concerned officials in Thursday’s meeting.Sources said it has been clearly stated that it will be the responsibility of the department to make up the loss. The Chief Minister will also be holding review meetings in this connection every two to three months.Soon after getting the direction of the Chief Minister, the officials of the department have started taking necessary steps to check ATC loss.It may be recalled that the state Power department has initiated steps to check power theft, by using aerial bunched (AB) cable for overhead wiring. Hundred places have been identified where AB cable will be used.It will help in checking ATC loss and the quality of power supply will also get improved. Steps have also been taken for underground laying of cables and it has already been implemented in Nabadwip and Bolpur. The same will be carried out in many other cities.Till March, the total number of commercial consumers was 15.93 lakh. It was 8.88 lakh in 2011. The number of consumers for agricultural purpose has increased to 2.86 lakh, which was 1.44 lakh in 2011.The number of industrial consumers was 1 lakh which was 78,074 till March 2011.last_img read more

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CMCH writes to guardians to urge students to end strike

first_imgKolkata: Calcutta Medical College and Hospital (CMCH) authorities on Saturday wrote to the guardians of the agitating medical students who have been staging demonstration inside the hospital campus for past six days with the demand for a new hostel.Few MBBS students of second, third and fourth years started hunger-strike to fulfill their demands. The CMCH authorities appealed to the parents of the medical students to withdraw the movement due to which two students have already fallen ill. The students taking part in the agitation alleged that the hostel meant for them was not in a good condition and the rooms are not up to the mark. The students also submitted a deputation to the CMCH principal on Tuesday placing their various demands. The hospital authorities have categorically mentioned that they will not be able to fulfill the demands. Some of the representatives of the medical students taking part in the agitation held a meeting with the principal of the CMCH and had a prolonged discussion regarding the same. But no solution has come out of it. Senior officials of the CMCH urged the students to lift the agitation which they have turned down. Students threatened to continue the demonstration till the demands are met. There has been no impact on the health services of the hospital. The second, third and fourth year MBBS students of the CMCH started the agitation after the first year students were given a new hostel by the authorities.last_img read more

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