LEEVENSPARK

Physical Chemistry Gold has been treasured throughout history partly because of its great chemical stability. Resistant to attack by oxygen, which rusts or tarnishes other metals, gold remains bright and beautiful under ordinary environmental conditions for centuries. Gold, however, does oxidize, forming Au2O3, when exposed to environments containing a highly reactive form of oxygen— e.g., atomic oxygen or ozone. Hans-Gerd Boyen of the University of Ulm, Ger., led a German-Swiss team that announced the discovery of a more oxidation-resistant form of gold. The material, called Au55, consists of gold nanoparticles; each nanoparticle is a tiny cluster comprising exactly 55 gold atoms and measuring about 1.4 nm (nanometres). Boyen's group reported that Au55 resisted corrosion under conditions that corroded bulk gold and gold nanoparticles consisting of either larger or smaller numbers of atoms. The researchers speculated that the chemical stability is conferred by special properties

Pinion Adjustment The pinion bearing preload adjustment depends on the type of spacer used to hold the bearings apart. Two main arrangements using a rigid spacer and a collapsible spacer are illustrated in Fig. 26.40. A bearing arrangement with a rigid spacer has a series of shims to control the static load on the bearings (Fig. 26.40A). On this arrangement the pinion nut is fully tightened before the preload is measured and shims are either added or removed if found incorrect. With this typeof spacer, the renewing of the pinion oil seal is simplified, because the seal replacement does not alter bearing preload provided the pinion nut is fully tightened Fig. 26.40. Pinion bearing adjustment The use of a collapsible spacer (Fig. 26.40B) saves time on the preload operation. While holding the bearings in alignment, this ductile steel spacer collapses under-pressure from the pinion nut so that the preload can be set in one operation. With the pinion, bearings and seal in position, the nut

Preloading of Bearing To support both the crown wheel and pinion, adjustable taper roller bearings are normally used in a final drive assembly. If each bearing is adjusted for a small clearance between the rollers and tracks, end-float and misalignment of the gear result. This causes gear noise and premature bearing failure, because of incorrect meshing and uneven loading respectively. Even if the clearance is removed, similar effects are produced due to the elasticity of the bearing material unless this is also taken into account. To overcome these problems, all adjustable bearings employed for final drives are preloaded by forcing them together to the position they occupy when the unit is under full load. Preloading is carried out through the means provided for the adjustment. In the case of pinion bearings the extent of this pre-compression is indicated by the torque required to rotate the pinion in its housing. The recommended preload normally states the conditions under which it i

Peculiar of the earth after the first shower The piquant, musky order that hangs in the air emanates an odorous chemical buried in the soil called ‘geosmin’ [literally, earth smell]. The smell is given off by Streptomyces bacteria, a genus belonging to the Actinomycetales order of gram actionmycetes. An asteroid heading toward Earth makes a good movie plot, but astronomers haven't yet found any heavenly bodies on such a collision course. There are plenty of asteroids in our neighborhood of the solar system, however, and a team of physicists has now discovered several new types of near-Earth-asteroid orbital motion. In the 27 September PRL they describe their theory and computer simulations of the orbits of three known asteroids. They conclude that although we are safe from collisions with such objects, there may be many asteroids inhabiting these newly discovered orbits, including undiscovered satellites of Earth. The orbits are examples of "coorbital motion," where

Parts of an automobile              The automobile as ‘a four-wheeled automotive vehicle designed primarily for passenger transportation    and commonly propelled by an internal-combustion engine using a volatile fuel’. A regular automobile roughly comprises of 14,000 parts that are again divisible into other structural and mechanical subsystems. The first in this list is the body of the automobile. It contains the passenger and storage space and the engine compartment. It is further classified according to the number of doors and the type of roof it has (e.g., two-door hardtop) and is made of molded steel, which is painted and treated to retard corrosion. The body rests upon the chassis, which is a steel frame that supports the engine, wheels, axle assemblies, transmission, steering mechanism, brakes, and suspension members. Most vehicles use the internal combustion gasoline engine with reciprocating pistons and a four-stroke cycle. A transmission includes shafts, gears and a clut

Automobile Pollution Internal combustion engines need a mixture of air and fuel to burn and produce energy to move the vehicle. It is these burnt gases which come out of the exhaust have the potential to cause pollution. In petrol engines the gases comprise of a mixture of unburnt hydrocarbons (HC), Carbon Monoxide (CO), Oxides of Nitrogen (NOx). It is a combination of these gases that which result in automobile pollution when they are in excess quantity. Within a certain range they are acceptable but when the engine is not tuned properly or a vehicle uses obsolete technology or the quality of fuel is not good then all these result in a higher level of emission of all the gases. If the air fuel mixture ratio is not correct then it increases the chances of pollution as it leads to inefficient. Also it leads to reduced power and fuel wastage, which in turn means less efficient performance of the engine along with lower fuel economy. 1.   Steps to check pollution In an effort to check aut

                        Power Assisted Steering Need for Power Assisted Steering A reduction in input effort on the steering wheel rim in a manual steering system is possible by decreasing the steering box gear ratio. This increases the number of steering wheel turns from lock to lock due to which manoeuvring of the steering takes longer, and accordingly the vehicle's safe cornering speed has to be reduced. Due to the requirement of more weight on the front steering wheels of front wheel drive cars and the use of radial ply tyres with greater tyre width, larger static turning torques are necessary. Therefore, for faster driving and cornering, power assisted steering is desirable and in some cases essential if the vehicle is to be handled to match its performance. Incorporation of power assisted steering on passenger cars reduces the drivers input to about 25 - 30% of the total effort needed otherwise to manoeuvre it. In heavy trucks the hydraulic power (servo) assistance can be in

Spy planes should come in the shape of a “bird” for better camouflage. Univerisity of Michigan has been awarded a 5-year grant of $10 millions for the development of some bat-like robotic spy planes. The bat-like spy plane has been given a acronym called COM-BAT which stands for U-M Center for Objective Microelectronics and Biomimetic Advanced Technology, which aims to re-establish the U.S Army as a world leader. The kind of bat-like spy planes are designed to provide short-term but real-time surveillance and feedback to the soldiers in the urban combat zones by using a collection of senses including sight, sound and smell. The main problem faced by the development of the COM-BAT is finding it a super lasting battery that allows it to fly long enough in the sky to collect all the necessary information for the soldiers before it drops to the ground. The development team is looking into possibility of get its power to be generated by vibrations, wind and also the sun, which the Un

A small poem on mechanicals........... We are we are we are the mechanicals, We cruiez the seas,                                                                                       We cut the euirs, We are we are we are the mechanicals,                                                                We power you, Put you to the space,                       We are we are ... From ages to ages we put the world out of the cagessmall to our ranges,  We make the wleels which gives the meals, We forge the problems to fine sharp solutions, We are we are ... We winged the world, We rigd the power, We are we are ... We mould the world into our cast, We dressed the world wih our knowledge.                                                -By Hari & Krishna We are we are we are "THE MECHANICALS" "BE PROUD TO BE A MECHANICAL ENGINEERS"

Image via Wikipedia The Roach Stuff: Packing for Mars                                                   Author Mary Roach about her new book Packing For Mars : The Curious Science of Life in the Void. In part 1 of this 2-part… read more... Mary Roach Is Packing For Mars (scientificamerican.com) A new book from author Mary Roach is always a welcome sight, even more so when it delves into the human side of spaceflight. In Packing for Mars, Roach explores what should be familiar ground to “spaceniks” and comes up with all kinds of fresh, surprising material, delivered with her trademark wit. Trust me, you’ll want to read all about Enos the space chimp, fights between astronauts, and the icky details of various bodily functions in space. read more....