Splines are ridges or teeth on a drive shaft that mesh with grooves in a mating piece and transfer torque to it, maintaining the angular correspondence between them. For instance, a gear mounted on a shaft might use a male spline on the shaft that matches the female spline on the gear; the splines on the pictured drive shaft match with the female splines in the center of the clutch plate, while the smooth tip of the axle is supported in the pilot bearing in the flywheel. An alternative to splines is a key, though splines provide a longer fatigue life. There are several types of splines: Parallel key spline where the sides of the spaced grooves are parallel in both directions and axial. Involute spline where the sides of the spaced grooves are involute, as with an involute gear, but not as tall; the curves increase strength by decreasing stress concentrations. Crowned splines where the sides of the spaced grooves are involute, but the male teeth are modified to allow for misalignment. Serrations where the sides of the spaced grooves form a "V".
These are used on small-diameter shafts. Helical splines where the spaced grooves form a helix about the shaft; the sides may be involute. This can either minimize stress concentrations for a stationary joint under high load, or allow for rotary and linear motion between the parts. Ball splines where the "teeth" of the outer part are implemented with a ball bearing to allow for free linear motion under high torque. Drive shafts on vehicles and power take-offs use splines to transmit torque and rotation and allow for changes in length. Splines are used in several places on bicycles; the crank arm to BB shaft interfaces that are splined include ISIS Drive, Truvativ GXP and Howitzer, Shimano's Octalink and many others, most of which are proprietary. Some cranksets feature modular spiders. Cassettes engage the freehub via a spline that has one groove wider than the others to enforce a fixed orientation. Disc brake mounting interfaces that are splined include Centerlock, by Shimano. Aircraft engines may have a spline upon.
There may be a master spline, wider than the others, so that the propeller may go on at only one orientation, to maintain dynamic balance. This arrangement is found in larger engines, whereas smaller engines use a pattern of threaded fasteners instead. There are two types of splines and external. External splines may be broached, milled, rolled, ground or extruded. There are fewer methods available for manufacturing internal splines due to accessibility restrictions. Methods include those listed above with the exception of hobbing. With internal splines, the splined portion of the part may not have a through-hole, which precludes use of a pull / push broach or extrusion-type method. If the part is small it may be difficult to fit a milling or grinding tool into the area where the splines are machined. To prevent stress concentrations the ends of the splines are chamfered; such stress concentrations are a primary cause of failure in poorly designed splines. Hirth joint Keyed joint Reeding Coupling Robert Rich Robins.
"Tooth Engagement Evaluation of Involute Spline Couplings". Brigham Young University. Retrieved 2010-07-08
Epaulette is a type of ornamental shoulder piece or decoration used as insignia of rank by armed forces and other organizations. In the French and other armies, epaulettes are worn by all ranks of elite or ceremonial units when on parade, it may bear rank or other insignia, should not be confused with a shoulder mark - called an shoulder board, rank slide, or slip-on - a flat cloth sleeve worn on the shoulder strap of a uniform. Epaulettes are fastened to the shoulder by a shoulder strap or passenten, a small strap parallel to the shoulder seam, the button near the collar, or by laces on the underside of the epaulette passing through holes in the shoulder of the coat. Colloquially, any shoulder straps with marks are called epaulettes; the placement of the epaulette, its color and the length and diameter of its bullion fringe are used to signify the wearer's rank. At the join of the fringe and the shoulderpiece is a metal piece in the form of a crescent. Although worn in the field, epaulettes are now limited to dress or ceremonial military uniforms.
Épaulette is a French word meaning "little shoulder". Epaulettes bear some resemblance to the shoulder pteruges of ancient Roman military costumes; however their direct origin lies in the bunches of ribbons worn on the shoulders of military coats at the end of the 17th century, which were decorative and intended to prevent shoulder belts from slipping. These ribbons were tied into a knot; this established the basic design of the epaulette as it evolved through the 18th and 19th centuries. From the 18th century on, epaulettes were used in the other armies to indicate rank; the rank of an officer could be determined by whether an epaulette was worn on the left shoulder, the right shoulder or on both. A "counter-epaulette" was worn on the opposite shoulder of those who wore only a single epaulette. Epaulettes were made in silver or gold for officers, in cloth of various colors for the enlisted men of various arms. Certain categories of cavalry wore flexible metal epaulettes referred to as shoulder scales worn on the field.
By the early 18th century, epaulettes had become the distinguishing feature of commissioned rank. This led officers of military units still without epaulettes to petition for the right to wear epaulettes, to ensure that their status would be recognized. During the Napoleonic Wars and subsequently through the 19th century, light infantry and other specialist categories of infantry in many European armies wore cloth epaulettes with wool fringes in various colours to distinguish them from ordinary line infantry. "Flying artillery" wore "wings", similar to an epaulette but with only a bit of fringe on the outside, which matched the shoulder seam. Heavy artillery wore small balls representing ammunition on their shoulders."An intermediate form in some services, such as the Russian Army, is the shoulder board, which neither has a fringe nor extends beyond the shoulder seam. This originated during the 19th century as a simplified version for service wear of the heavy and conspicuous full dress epaulette with bullion fringes.
Today, epaulettes have been replaced by a five-sided flap of cloth called a shoulder board, sewn into the shoulder seam and the end buttoned like an epaulette. From the shoulder board was developed the shoulder mark, a flat cloth tube, worn over the shoulder strap and carries embroidered or pinned-on rank insignia; the advantages of this are the ability to change the insignia as occasions warrant. Airline pilot uniform shirts include cloth flattened tubular epaulettes having cloth or bullion braid stripes, attached by shoulder straps integral to the shirts; the rank of the wearer is designated by the number of stripes: Traditionally four for captain, three for first officer, two for second officer. However, rank insignia are airline specific. For example, at some airlines, two stripes denote junior first officer and one stripe second officer. Airline captains' uniform caps will have a braid pattern on the bill. In the Belgian army, red epaulettes with white fringes are worn with the ceremonial uniforms of the Royal Escort while red ones are worn by the Grenadiers.
Trumpeters of the Royal Escort are distinguished by all red epaulettes while officers of the two units wear silver or gold respectively. In the Canadian Armed Forces, epaulettes are still worn on some Army Full Dress, Patrol Dress, Mess Dress uniforms. Epaulettes in the form of shoulder boards are worn with the officer's white Naval Service Dress. After the unification of the Forces, prior to the issue of the Distinct Environmental Uniforms, musicians of the Band Branch wore epaulettes of braided gold cord; until 1914, officers of most French Army infantry regiments wore gold epaulettes in full dress, while those of mounted units wore silver. No insignia was worn on the epaulette itself, though the bullion fringe falling from the crescent differed according to rank. Other ranks of most branches of the infantry, as well as cuirassiers wore detachable epaulettes of various colours with woollen fringes, of a traditional pattern that dated back to the 18th Century. Other cavalry such as hussars and chasseurs à cheval wore special epaulettes of a style intended to deflect sword blows from the shoulder.
In the modern French Army, epaulettes are still worn by those units retaining 19th-century-style full dress uniforms, notably the ESM Saint-Cyr and the
A washing machine is a device used to wash laundry. The term is applied to machines that use water as opposed to dry cleaning or ultrasonic cleaners; the user adds laundry detergent, sold in liquid or powder form to the wash water. Laundering by hand involves soaking, beating and rinsing dirty textiles. Before indoor plumbing, the washerwoman or housewife had to carry all the water used for washing and rinsing the laundry. Water for the laundry would be hand carried, heated on a fire for washing poured into the tub; that made the warm soapy water precious. Removal of soap and water from the clothing after washing was a separate process. First, soap would be rinsed out with clear water. After rinsing, the soaking wet clothing would be formed into a roll and twisted by hand to extract water; the entire process occupied an entire day of hard work, plus drying and ironing. It is often used in washbasins. Clothes washer technology developed as a way to reduce the manual labor spent, providing an open basin or sealed container with paddles or fingers to automatically agitate the clothing.
The earliest machines were hand-operated and constructed from wood, while machines made of metal permitted a fire to burn below the washtub, keeping the water warm throughout the day's washing. The earliest special-purpose mechanical washing device was the washboard, invented in 1797 by Nathaniel Briggs of New Hampshire. By the mid-1850s steam-driven commercial laundry machinery were on sale in the UK and US. Technological advances in machinery for commercial and institutional washers proceeded faster than domestic washer design for several decades in the UK. In the United States there was more emphasis on developing machines for washing at home, though machines for commercial laundry services were used in the late 19th and early 20th centuries; the rotary washing machine was patented by Hamilton Smith in 1858. As electricity was not available until at least 1930, some early washing machines were operated by a low-speed, single-cylinder hit-and-miss gasoline engine. After the items were washed and rinsed, water had to be removed by twisting.
To help reduce this labor, the wringer/mangle machine was developed. As implied by the term "mangle," these early machines were quite dangerous if powered and not hand-driven. A user's fingers, arm, or hair could become entangled in the laundry being squeezed, resulting in horrific injuries. Safer mechanisms were developed over time, the more hazardous designs were outlawed; the mangle used two rollers under spring tension to squeeze water out of clothing and household linen. Each laundry item would be fed through the wringer separately; the first wringers were hand-cranked, but were included as a powered attachment above the washer tub. The wringer would be swung over the wash tub so that extracted wash water would fall back into the tub to be reused for the next load; the modern process of water removal by spinning did not come into use until electric motors were developed. Spinning requires a constant high-speed power source, was done in a separate device known as an "extractor". A load of washed laundry would be transferred from the wash tub to the extractor basket, the water spun out in a separate operation.
These early extractors were dangerous to use, since unevenly distributed loads would cause the machine to shake violently. Many efforts were made to counteract the shaking of unstable loads, such as mounting the spinning basket on a free-floating shock-absorbing frame to absorb minor imbalances, a bump switch to detect severe movement and stop the machine so that the load could be manually redistributed. What is now referred to as an automatic washer was at one time referred to as a "washer/extractor", which combined the features of these two devices into a single machine, plus the ability to fill and drain water by itself, it is possible to take this a step further, to merge the automatic washing machine and clothes dryer into a single device, called a combo washer dryer. The first English patent under the category of Washing machines was issued in 1691. A drawing of an early washing machine appeared in the January 1752 issue of The Gentleman's Magazine, a British publication. Jacob Christian Schäffer's washing machine design was published 1767 in Germany.
In 1782, Henry Sidgier issued a British patent for a rotating drum washer, in the 1790s Edward Beetham sold numerous "patent washing mills" in England. One of the first innovations in washing machine technology was the use of enclosed containers or basins that had grooves, fingers, or paddles to help with the scrubbing and rubbing of the clothes; the person using the washer would use a stick to press and rotate the clothes along the textured sides of the basin or container, agitating the clothes to remove dirt and mud. This crude agitator technology was hand-powered, but still more effective than hand-washing the clothes. More advancements were made to washing machine technology in the form of the rotative drum design; these early design patents consisted of a drum washer, hand-cranked to make the wooden drums rotate. While the technology was simple enough, it was a milestone in the history of washing machines, as it introduced the idea of "powered" washing drums; as metal drums st
1 euro cent coin
The 1 euro cent coin has a value of one hundredth of a euro and is composed of copper-covered steel. The coins of every Euro country have a common reverse and each has a country-specific obverse; the coin has been used since 2002 and was not redesigned in 2007 as was the case with the higher-value coins. The coin dates from 2002, when euro coins and banknotes were introduced in the 12-member eurozone and its related territories; the common side was designed by Luc Luycx, a Belgian artist who won a Europe-wide competition to design the new coins. The design of the 1- to 5-cent coins was intended to show the European Union's place in the world, as opposed to the one- and two-euro coins showing the 15 states as one and the 10- to 50-cent coins showing separate EU states; the national sides 15, were each designed according to national competitions, though to specifications which applied to all coins, such as the requirement of including twelve stars. National designs were not allowed to change until the end of 2008, unless a monarch dies or abdicates.
This happened in Monaco and the Vatican City, resulting in three new designs in circulation. National designs have seen some changes due to new rules stating that national designs should include the name of the issuing country; as the EU's membership has since expanded in 2004 and 2007, with further expansions envisaged, the common face of all euro coins from the value of 10 cents and above were redesigned in 2007 to show a new map. The 1- to 5-cent coins, did not change, as the highlighting of the old members over the globe was so faint it was not considered worth the cost. However, new national coin designs were added: in 2007 for Slovenia; the coins are composed of copper-covered steel, with a diameter of 16.25 mm, a 1.67 mm thickness and a mass of 2.30 grams. The coins' edges are smooth; the coins have been used from 2002, though some are dated 1999, the year the euro was created as a currency, but not put into general circulation. The reverse displays a globe in the bottom right; the then-fifteen members of the EU are highlighted and the northern half of Africa and the western half of Asia are shown.
Six fine lines cut diagonally behind the globe from each side of the coin and have twelve stars at their ends. To the top left is a large number 1 followed, in smaller text, by the words "EURO CENT"; the designers initials, LL, appear to the right of the globe. The obverse side of the coin depends on the issuing country. All have to include the engravers initials and the year of issue. New designs have to include the name or initials of the issuing country; the side cannot repeat the denomination of the coin unless the issuing country uses an alphabet other than Latin. Austria and Greece will at some point need to update their designs to comply with guidelines stating they must include the issuing state's name or initial, not repeat the denomination of the coin. In addition, there are several EU states that have not yet adopted the euro, some of them have agreed upon their coin designs. See enlargement of the Eurozone for expected entry dates of these countries; the one- and two-cent coins were introduced to ensure that the transition to the euro was not used as an excuse by retailers to round up prices.
However, due to the cost of maintaining a circulation of low-value coins by business and the mints, Ireland and the Netherlands round prices to the nearest five cents if paying by cash, while producing only a handful of those coins for collectors, rather than general circulation. Despite this, the coins are still legal tender and produced outside these states, so if customers with one-cent coins minted elsewhere wish to pay with them, they may; the Nederlandse Bank calculated. Other countries such as Germany favoured retaining the coins due to retailers' desire for €1.99 prices, which appear more attractive to the consumer than €2.00. According to a Eurobarometer survey of EU citizens, 64% across the Eurozone want their removal with prices rounded. Only Portugal and Latvia had a plurality in favour of retaining the coins. In Flemish, the 1 - to 5-cent coins have the nickname ros or rostjes due to their colour. In Portugal, the 1-cent coin gained the nicknames botão, feijão and pretos due to its small size and value: instead of gambling with real money, buttons sometimes are used.
"National sides: 1 cent". European Central Bank. Retrieved 18 August 2009
An axial-flow pump, or AFP, is a common type of pump that consists of a propeller in a pipe. The propeller can be driven directly by a sealed motor in the pipe or by electric motor or petrol/diesel engines mounted to the pipe from the outside or by a right-angle drive shaft that pierces the pipe. Fluid particles, in course of their flow through the pump, do not change their radial locations since the change in radius at the entry and the exit of the pump is small. Hence the name "axial" pump. An axial flow pump has a propeller-type of impeller running in a casing; the pressure in an axial flow pump is developed by the flow of liquid over the blades of impeller. The fluid is pushed in a direction parallel to the shaft of the impeller, that is, fluid particles, in course of their flow through the pump, do not change their radial locations, it allows the fluid to discharge the fluid nearly axially. The propeller of an axial flow pump is driven by a motor; the fixed diffuser vanes are used to remove the whirl component of the discharge velocity of the impeller and to convert the energy to pressure.
The impeller vanes may be adjustable. The machine may be fitted with pre-entry vanes to eliminate pre-rotation and to make the flow purely axial. Work done on the fluid per unit weight = U g where U = U 2 = U 1 is the blade velocity. For maximum energy transfer, V w 1 = 0, that is, α 1 = 90 deg Therefore, from outlet velocity triangle, we have V w 2 = U − V f 2 cot β 2 Therefore, the maximum energy transfer per unit weight by an axial flow pump = U g In an axial flow pump, blades have an airfoil section over which the fluid flows and pressure is developed. For a constant flow, we have V f 1 = V f 2 = V f So, the maximum energy transfer to the fluid per unit weight will be U g For constant energy transfer over the entire span of the blade, the above equation should be constant for all values of r. But, U 2 will increase with an increase in radius r, therefore to maintain a constant value an equal increase in U V f cot β 2 must take place. Since, V f is constant, therefore cot β 2 must increase on increasing r.
So, the blade is twisted as the radius changes. The performance characteristics of an axial flow pump is shown in the figure; as shown in the figure, the head at the zero flow rate can be as much as three times the head at the pump’s best efficiency point. The power requirement increases as the flow decreases, with the highest power drawn at the zero flow rate; this characteristic is opposite to that of a radial flow centrifugal pump where power requirement increases with an increase in the flow. The power requirements and pump head increases with an increase in pitch, thus allowing the pump to adjust according to the system conditions to provide the most efficient operation; the main advantage of an axial flow pump is that it has a high discharge at a low head. For example, it can pump up to 3 times more water and other fluids at lifts of less than 4 meters as compared to the more common radial-flow or centrifugal pump, it can be adjusted to run at peak efficiency at low-flow/high-pressure and high-flow/low-pressure by changing the pitch on the propeller.
The effect of turning of the fluid is not too severe in an axial pump and the length of the impeller blades is short. This leads to lower higher stage efficiencies; these pumps have the smallest of the dimensions among many of the conventional pumps and are more suited for low heads and higher discharges. One of the most common applications of AFPs would be in handling sewage from commercial and industrial sources. In sailboats, AFPs are used in transfer pumps used for sailing ballast. In power plants, they
Axial fan design
An axial fan is a type of fan that causes gas to flow through it in an axial direction, parallel to the shaft about which the blades rotate. The flow is axial at exit; the fan is designed to produce a pressure difference, hence force, to cause a flow through the fan. Factors which determine the performance of the fan include the shape of the blades. Fans have many applications including in cooling towers. Design parameters include flow rate, pressure rise and efficiency. Axial fans comprise fewer blades than ducted fans. Axial fans have larger radius and lower speed than ducted fans. Since the calculation cannot be done using the inlet and outlet velocity triangles, not the case in other turbomachines, calculation is done by considering a mean velocity triangle for flow only through an infinitesimal blade element; the blade is divided into many small elements and various parameters are determined separately for each element. There are two theories that solve the parameters for axial fans: Slipstream Theory Blade Element Theory In the figure, the thickness of the propeller disc is assumed to be negligible.
The boundary between the fluid in motion and fluid at rest is shown. Therefore, the flow is assumed to be taking place in an imaginary converging duct where: D = Diameter of the Propeller Disc. Ds = Diameter at the Exit. In the figure, across the propeller disc, velocities cannot change abruptly across the propeller disc as that will create a shockwave but the fan creates the pressure difference across the propeller disc. C 1 = C 2 = C and P 1 ≠ P 2 The area of the propeller disc of diameter D is: A = π D 2 4 The mass flow rate across the propeller is: m ˙ = ρ A C Since thrust is change in mass multiplied by the velocity of the mass flow i.e. change in momentum, the axial thrust on the propeller disc due to change in momentum of air, which is: F x = m ˙ = ρ A C Applying Bernoulli's principle upstream and downstream: P a + 1 2 ρ C u 2 = P 1 + 1 2 ρ C 2 P a + 1 2 ρ C s 2 = P 2 + 1 2 ρ C 2 On subtracting the above equations: P 2 − P 1 = 1 2 ρ Thrust difference due to pressure difference is projected area multiplied by the pressure difference.
Axial thrust due to pressure difference comes out to be: F x = A = 1 2 ρ A Comparing this thrust with the axial thrust due to change in momentum of air flow, it is found that: C = C s + C u 2 A parameter'a' is defined such that - C = C u where a = C C u − 1 Using the previous equation and "a", an expression for Cs comes out to be: C s = C u Calculating the change in specific stagnation enthalpy across disc: Δ h o = Δ h o d − Δ h o u = ( h d + 1 2
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object. Energy is a conserved quantity; the SI unit of energy is the joule, the energy transferred to an object by the work of moving it a distance of 1 metre against a force of 1 newton. Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object's position in a force field, the elastic energy stored by stretching solid objects, the chemical energy released when a fuel burns, the radiant energy carried by light, the thermal energy due to an object's temperature. Mass and energy are related. Due to mass–energy equivalence, any object that has mass when stationary has an equivalent amount of energy whose form is called rest energy, any additional energy acquired by the object above that rest energy will increase the object's total mass just as it increases its total energy. For example, after heating an object, its increase in energy could be measured as a small increase in mass, with a sensitive enough scale.
Living organisms require exergy to stay alive, such as the energy. Human civilization requires energy to function, which it gets from energy resources such as fossil fuels, nuclear fuel, or renewable energy; the processes of Earth's climate and ecosystem are driven by the radiant energy Earth receives from the sun and the geothermal energy contained within the earth. The total energy of a system can be subdivided and classified into potential energy, kinetic energy, or combinations of the two in various ways. Kinetic energy is determined by the movement of an object – or the composite motion of the components of an object – and potential energy reflects the potential of an object to have motion, is a function of the position of an object within a field or may be stored in the field itself. While these two categories are sufficient to describe all forms of energy, it is convenient to refer to particular combinations of potential and kinetic energy as its own form. For example, macroscopic mechanical energy is the sum of translational and rotational kinetic and potential energy in a system neglects the kinetic energy due to temperature, nuclear energy which combines utilize potentials from the nuclear force and the weak force), among others.
The word energy derives from the Ancient Greek: translit. Energeia, lit.'activity, operation', which appears for the first time in the work of Aristotle in the 4th century BC. In contrast to the modern definition, energeia was a qualitative philosophical concept, broad enough to include ideas such as happiness and pleasure. In the late 17th century, Gottfried Leibniz proposed the idea of the Latin: vis viva, or living force, which defined as the product of the mass of an object and its velocity squared. To account for slowing due to friction, Leibniz theorized that thermal energy consisted of the random motion of the constituent parts of matter, although it would be more than a century until this was accepted; the modern analog of this property, kinetic energy, differs from vis viva only by a factor of two. In 1807, Thomas Young was the first to use the term "energy" instead of vis viva, in its modern sense. Gustave-Gaspard Coriolis described "kinetic energy" in 1829 in its modern sense, in 1853, William Rankine coined the term "potential energy".
The law of conservation of energy was first postulated in the early 19th century, applies to any isolated system. It was argued for some years whether heat was a physical substance, dubbed the caloric, or a physical quantity, such as momentum. In 1845 James Prescott Joule discovered the generation of heat; these developments led to the theory of conservation of energy, formalized by William Thomson as the field of thermodynamics. Thermodynamics aided the rapid development of explanations of chemical processes by Rudolf Clausius, Josiah Willard Gibbs, Walther Nernst, it led to a mathematical formulation of the concept of entropy by Clausius and to the introduction of laws of radiant energy by Jožef Stefan. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time. Thus, since 1918, theorists have understood that the law of conservation of energy is the direct mathematical consequence of the translational symmetry of the quantity conjugate to energy, namely time.
In 1843, James Prescott Joule independently discovered the mechanical equivalent in a series of experiments. The most famous of them used the "Joule apparatus": a descending weight, attached to a string, caused rotation of a paddle immersed in water insulated from heat transfer, it showed that the gravitational potential energy lost by the weight in descending was equal to the internal energy gained by the water through friction with the paddle. In the International System of Units, the unit of energy is the joule, named after James Prescott Joule, it is a derived unit. It is equal to the energy expended in applying a force of one newton through a distance of one metre; however energy is expressed in many other units not part of the SI, such as ergs, British Thermal Units, kilowatt-hours and kilocalories, which require a conversion factor when expressed in SI units. The SI unit of energy rate is the watt, a joule per second. Thus, one joule is one watt-second, 3600 joules equal one wa