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Our speculum metal mirror is about the same size as that for the reflecting telescope with which William Herschel discovered the planet Uranus in 1781 – the first planet to be discovered with a telescope. We have a similar reflecting telescope made by Herschel on display in the Science City gallery, as well as the mirror which we had specially made. Diegel O, Nordin A, Motte D (2019) A practical guide to design for additive manufacturing. Springer Singapore. https://doi.org/10.1007/978-981-13-8281-9 Many functionalities are demanded to this subsystem. Since it is under rotation, the mechanical balancing must be assured through an adequate stabilization to take care of the deformation which may affect the reflective surface. Modern LIDAR systems for aerospace applications require complex optical elements whose performance and lighter weight must be improved to meet growing application requirements. Metallic optics are a good choice to achieve the desired performance. There has been some discussion about whether infection changes human behaviour or not, possibly making some infected humans more likely to take risks, but it's certainly not a dramatic behavioural change like we see with zombies. Using the simulation, it is possible to choose the best lattice structure that would provide the maximum lightening of the mirror. Obviously, the greater the length of the beams in the lattice structure, the greater the volume of the cell and thus the greater the weight reduction.
The inner powders removal was carefully controlled and a T6 thermal cycle was provided in a Nabertherm LH120/14 controlled atmosphere hoven. The heat inducing laser fusion process results in a significant residual stress and, therefore, in an unstable mirror [ 36, 37]. A stress relieving heat treatment was applied according to the following characteristics: the mirror was slowly heated at 5 °C/min rate up to the soaking temperature of 550 °C and maintained for 1.5 h; after a water quenching, an aging at 165 °C for 24 h was provided. AlMangour B (2019) Additive manufacturing of emerging materials. Springer Nature, Cham, Switzerland. Boschetto A, Bottini L, Veniali F (2017) Roughness modeling of AlSi10Mg parts fabricated by selective laser melting. J Mater Process Technol 241:154–163. https://doi.org/10.1016/j.jmatprotec.2016.11.013Liu G, Guo L, Wang X, Wu Q (2018) Topology and parametric optimization based lightweight design of a space reflective mirror. Opt Eng 57(7):1. https://doi.org/10.1117/1.OE.57.7.075101 We must prioritise and put more funding behind scientific and multi-disciplinary research. At the moment, Arctic science is concentrated on its summer, with the Arctic winter which could tell us an enormous amount about the weather being under-studied. More collaboration is needed among UK universities to avoid repetition of scientific endeavours seeking out the same information, and with our international partners to learn and share resource."
Xu C, Peng X, Liu J et al (2022) (2022) A high efficiency and precision smoothing polishing method for NiP coating of metal mirror. Micromachines 13:1171. https://doi.org/10.3390/mi13081171 The mirror disc’s concave surface then had to be ground against another metal disc with an equally matching convex surface. This grinds out imperfections from the casting process to make the mirror smoother and more reflective and helps to grind a more accurate curve into the mirror. Terry ground the mirror against the convex disc using ever finer pastes of water mixed with sand, from coarse, gritty grades right down to ground pumice stone as smooth as flour. He then polished it to a high shine on a bed of slightly softened set pitch, or tar, with polishing powder. This is exactly what earlier astronomers did: William Herschel ground his speculum metal mirrors with coarse emery and water; Newton polished his on a bed of pitch while John Hadley similarly used pitch-soaked silk. Left: The coarsest sand used for grinding the mirror. Sand sold in pet shops to line birdcages proved particularly effective! Right: The bed of pitch, also known as the pitch-lap or polishing-lap, on which the mirror was finally polished. Credit: Matthew Howles. Following that statement, Bernard knows that May and June are ruled out. Then, Bernard is able to know which month it is. So it must be either July 16, August 15, or August 17 (not the 14th as then he can't know for sure whether it's July or August). Since Albert subsequently can also be sure of the date, he must know it's July. If it's August, he can't be sure as it could be August 15 or 17." The choice was made to use a star trabecular structure which allows excellent quality in the fabrication of the beams, when properly inclined, using SLM technology.
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To celebrate International Astronomy Day, Assistant Curator Matthew Howles takes an in-depth look at the most iconic of astronomical instruments: the telescope. Parry LA, Ashcroft IA, Wildman RD (2019) Geometrical effects on residual stress in selective laser melting. Addit Manuf 25:166–175. https://doi.org/10.1016/j.addma.2018.09.026 Due to climate warming, irreversibly thawing permafrost is releasing organic matter frozen for up to a million years, most of which decomposes into carbon dioxide and methane, further enhancing the greenhouse effect. The main objective of the re-design is the weight reduction maintaining the strict mechanical constraints on deformation and static balance as the part rotates at high speed. For the scope, the mirror body and inner lattice structures are modeled using FEM. The mirror was verified by means of the interferometric measurement. Two testing configurations were considered: free and screwed. In the former the mirror was simply placed on the support. In the latter, the mirror was fixtured by tightening the screws used for the final assembly with the nominal torque of 1.6 Nm required by the application.
A static balancing of this lightened mirror was provided. In particular, the original mass of 205 g was reduced to 154 g. Therefore, the mirror total mass was cut by 25% (from 415 to 311.8 g). In the question, you're given 10 dates across four months - May 15, 16, and 19, June 17 and 19, July 14 and 16, and August 14, 15, and 17. Then, you're given a couple of cryptic quotes from Albert, who only knows the month Cheryl was born, and Bernard, who only knows the date. Your job, with the dates provided and the cryptic quotes from the two men in the question, is to work out when Cheryl's birthday is. Can you do it? It's definitely a head-scratcher, so we'll give you a little bit of time, but once you're ready, scroll down to find out the answer! Solution
The dynamic analysis showed smaller displacements than the case the mirror is assembled via tightening the screws;
A tweet with almost 7,000 likes said: "How is a zombie virus get buried in a frozen lake? And why did they dig it up? That doesn't even make sense". We had a go at making speculum metal telescope mirrors – arsenic NOT included – as part of a “how-it’s-made” film for the Science City gallery. We wanted to showcase some of the extraordinary craft skills needed to produce many of the historical scientific instruments in our collection. Maconachie T, Leary M, Lozanovski B et al (2019) SLM lattice structures: properties, performance, applications and challenges. Mater Des 183:108137. https://doi.org/10.1016/j.matdes.2019.108137 Speaking to Newsweek, professor in epidemiology at Kent State University of Public Health Tara C. Smith discussed the realities of a zombie apocalypse.
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The prescreening simulation allowed the selection of a lattice structure with good compromise between mass reduction and maximum displacement; Mirrors manufacturing with traditional computer numerical control (CNC) technologies have limitations on mass reduction. Additive manufacturing (AM) methods offer new concepts for production of metal optics that can overcome the specific limitations of CNC technologies. Internal structures can be designed with a variety of configurations, such as periodic structures [ 6], honeycomb cells [ 7, 8] , and topologically optimized structures [ 9, 10, 11]. Milan B (2016) Laser additive manufacturing. Materials, Design, Technologies, and Applications. Woodhead Publishing, Cambridge The question - which has since been shared on social media - starts off like this: "Albert and Bernard just became friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates. Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively."
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