1.
VRLA battery
–
A VRLA battery stands for more commonly known as a sealed lead-acid, gel cell, or maintenance free battery, is a type of lead-acid rechargeable battery. Due to their construction, the Gel and Absorbent Glass Mat types of VRLA can be mounted in any orientation, the term maintenance free is a misnomer as VRLA batteries still require cleaning and regular functional testing. There are three types of VRLA batteries, Sealed VR wet cell, AGM and Gel. Gel cells add silica dust to the electrolyte, forming a thick putty-like gel and these are sometimes referred to as silicone batteries. AGM batteries feature fiberglass mesh between the plates which serves to contain the electrolyte. Both designs offer advantages and disadvantages compared to batteries and sealed VR wet cells. Lead-acid cells consist of two plates of lead, which serve as electrodes, suspended in diluted sulphuric acid, which is then the electrolyte, in conventional lead-acid cells, the diluted acid is in liquid form, hence the term flooded or wet cells. The wet cell type contains acid in the liquid form similarly to the lead acid batteries. When a cell discharges, the lead and diluted acid undergo a reaction that produces lead sulphate. When a cell is charged, the lead sulphate and water are turned back into lead. In all lead-acid battery designs, charge current must be adjusted to match the ability of the battery to absorb the energy. If these gases are allowed to escape, as in a conventional flooded cell, in contrast, in VRLA batteries the gases are retained within the battery as long as the pressure remains within safe levels. Under normal operating conditions the gases can then recombine within the battery itself, sometimes with the help of a catalyst, and no topping-up is needed. However, if the pressure exceeds safety limits, safety valves open to allow the gases to escape. In flooded lead-acid batteries, the electrolyte is a hazard during shipping. Furthermore, the need to water levels makes them unsuitable for maintenance-free applications. The immobilized electrolyte in VRLA batteries addresses these problems, at the same time, since VRLA cells cant be topped off with water, any hydrogen lost during outgassing cant easily be replaced. To some extent, this can be compensated for by overprovisioning the quantity of electrolyte, the main downside to the VRLA design is that the immobilizing agent also impedes the chemical reactions that generate current
2.
Double wishbone suspension
–
In automobiles, a double wishbone suspension is an independent suspension design using two wishbone-shaped arms to locate the wheel. Each wishbone or arm has two mounting points to the chassis and one joint at the knuckle, the shock absorber and coil spring mount to the wishbones to control vertical movement. The double-wishbone suspension can also be referred to as double A-arms, though the arms themselves can be A-shaped, L-shaped, a single wishbone or A-arm can also be used in various other suspension types, such as variations of the MacPherson strut. The upper arm is shorter to induce negative camber as the suspension jounces. When the vehicle is in a turn, body roll results in positive camber gain on the lightly loaded inside wheel, between the outboard end of the arms is a knuckle. The knuckle contains a kingpin for horizontal radial movement in older designs, in newer designs, a ball joint at each end allow for all movement. Attached to the knuckle at its center is a hub, or in many older designs. To resist fore-aft loads such as acceleration and braking, the arms require two bushings or ball joints at the body. At the knuckle end, single ball joints are used, in which case the steering loads have to be taken via a steering arm. An L-shaped arm is generally preferred on passenger vehicles because it allows a better compromise of handling and comfort to be tuned in. The bushing in line with the wheel can be kept relatively stiff to effectively handle cornering loads while the joint can be softer to allow the wheel to recess under fore-aft impact loads. For a rear suspension, a pair of joints can be used at both ends of the arm, making them more H-shaped in plan view. Alternatively, a fixed-length driveshaft can perform the function of a wishbone as long as the shape of the other wishbone provides control of the upright and this arrangement has been successfully used in the Jaguar IRS. In elevation view, the suspension is a 4-bar link, and it is easy to work out the camber gain, the various bushings or ball joints do not have to be on horizontal axes, parallel to the vehicle centre line. If they are set at an angle, then anti-dive and anti-squat geometry can be dialled in, in many racing cars, the springs and dampers are relocated inside the bodywork. The suspension uses a bellcrank to transfer the forces at the end of the suspension to the internal spring. This is then known as a rod if bump travel pushes on the rod. As the wheel rises, the push rod compresses the spring via a pivot or pivoting system
3.
Apollo (spacecraft)
–
The Apollo spacecraft was composed of three parts designed to accomplish the American Apollo programs goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth. The expendable spacecraft consisted of a combined Command/Service Module and a Lunar Module, the design was based on the Lunar Orbit Rendezvous approach, two docked spacecraft were sent to the Moon and went into lunar orbit. While the LM separated and landed, the CSM remained in orbit, after the lunar excursion, the two craft rendezvoused and docked in lunar orbit, and the CSM returned the crew to Earth. The Command Module was the part of the space vehicle that returned with the crew to the Earths surface. The LES was jettisoned during launch upon reaching the point where it was no longer needed, two unmanned CSMs, one unmanned LM and one manned CSM were carried into space by Saturn IB launch vehicles for low Earth orbit Apollo missions. After conclusion of the Apollo program, four CSMs were launched on Saturn IBs for three Skylab Earth orbital missions and the Apollo-Soyuz Test Project. The major part of the Apollo spacecraft was a vehicle designed for Earth orbital, translunar, and lunar orbital flight. This consisted of a command module supported by a service module, the Command Module was the control center for the Apollo spacecraft and living quarters for the three crewmen. It was the part of the Apollo/Saturn space vehicle that returned to Earth intact. The oxygen was used for breathing, and the fuel cells produced water for drinking. On Apollo 15,16 and 17 it also carried an instrument package, with a mapping camera. A major portion of the module was taken up by propellant. Capable of multiple restarts, this placed the Apollo spacecraft into and out of lunar orbit. The Service Module remained attached to the Command Module throughout the mission and it was jettisoned just prior to reentry into the Earths atmosphere. The Lunar Module was a vehicle designed to land on the Moon and return to lunar orbit. It consisted of a descent stage and an ascent stage and it supplied life support systems for two astronauts for up to four to five days on the Apollo 15,16 and 17 missions. The spacecraft was designed and manufactured by the Grumman Aircraft Company, the descent stage contained the landing gear, landing radar antenna, descent rocket engine, and fuel to land on the moon. The Spacecraft Lunar Module Adapter, built by North American Aviation, was an aluminum structure which supported the Service Module above the Saturn S-IVB rocket stage
4.
Stereolithography
–
Those polymers then make up the body of a three-dimensional solid. Research in the area had been conducted during the 1970s, and he then set up 3D Systems Inc to commercialize his patent. Stereolithography or SLA printing is an early and widely used 3D printing technology, the word is a portmanteau of the Greek words stereon, lithos and graphy. Also known as additive manufacturing, 3D printing was invented with the intent of allowing engineers to create prototypes of their designs in a more effective manner. The technology first appeared as early as the 1970s, japanese researcher Dr. Hideo Kodama first invented the modern layered approach to stereolithography by using ultraviolet light to cure photosensitive polymers. On July 16,1984, three weeks before Chuck Hull filed his own patent, Alain Le Mehaute, Olivier de Witte, the French inventors patent application was abandoned by the French General Electric Company and CILAS. Le Mehaute believes that the abandonment reflects a problem with innovation in France, however, the term “stereolithography” was coined in 1986 by Chuck Hull. Hulls patent described a concentrated beam of light focused onto the surface of a vat filled with a liquid photopolymer. The UV light beam is focused onto the surface of the liquid photopolymer, in 1986, Hull founded the worlds first 3D printing company, 3D Systems Inc, which is currently based in Rock Hill, SC. Stereolithographys success in the automotive industry allowed 3D printing to achieve industry status, attempts have been made to construct mathematical models of stereolithography processes and to design algorithms to determine whether a proposed object may be constructed using 3D printing. Stereolithography is a manufacturing process that works by focusing an ultraviolet laser on to a vat of photopolymer resin. With the help of computer aided manufacturing or computer aided design software, because photopolymers are photosensitive under ultraviolet light, the resin is solidified and forms a single layer of the desired 3D object. This process is repeated for each layer of the design until the 3D object is complete, in models featuring an elevator apparatus, an elevator platform descends a distance equal to the thickness of a single layer of the design into the photopolymer vat. Then, a resin-filled blade sweeps across a section of the layer. The subsequent layer is traced, joining the previous layer, a complete 3D object can be formed using this process. Designs are then immersed in a bath in order to remove any excess resin. It is also possible to print objects bottom up by using a vat with a flexible, transparent bottom. For example, the Form 1 stereolithography machine starts a print by lowering the build platform to touch the bottom of the resin-filled vat, then moving upward the height of one layer
5.
School Library Association
–
The School Library Association is an independent organization in the United Kingdom which promotes libraries and literacy in schools. The SLA was founded in 1937 and is based at Kembrey Park in north-eastern Swindon and it is a charity registered in England & Wales and Scotland. It provides training and information to teachers and librarians, promotes the role of librarians in schools and publishes a range of titles including a quarterly journal, regional branches operate in many areas of the UK and there is a national branch, SLARI, in the Republic of Ireland. The Associations President is Kevin Crossley-Holland, past Presidents include authors Gervase Phinn and Aidan Chambers and Miranda McKearney, Director of The Reading Agency. Two chief executives of the association have been honoured for their services to education, Valerie Ann Fea in the New Year Honours 1997, Boys into Books 5–11, a follow up project funded by the DCSF, ran in 2008, also with a published reading guide. In 2010 the SLA ran the Everyones Reading campaign in association with the DCSF, a brilliant project encouraging the enjoyment of reading, a reading culture and a pleasure that will last throughout readers lives. The SLA founded the School Librarian of the Year Award in 2004 to highlight best practice and this was superseded in 2014 by the SLA Inspiration Award for the school library space that shows inspiration, innovation, creativity and resourcefulness in its library design and in use. 2011 – How to Make a Universe with 92 Ingredients by Adrian Dingle 2012 – Can We Save the Tiger, School Library Association, registered charity no.313660. School Library Association, Registered Charity no, office of the Scottish Charity Regulator. Book Ahead Boys into Books Everyones Reading
