Tuesday, 6 December 2016

Road works

Road works
On some sites you will first need to demolish houses and other structures that impede construction. After that, proceed to one of the main processes - the excavation and moving huge amounts of soil and rocks, and up to tens of millions of tons.
That the line lay on a horizontal surface, large masses of soil from the raised territories pour in low-lying areas. This method is called working with the bookmark. Taken while routing the top layer of soil is used to cover road shoulders, embankments, and the Central dividing strips, and then planted with a grass and other vegetation.
To drain water to the edges of the road surface has a convex shape (curvature profile). At the beginning of construction for water collection laid for a powerful drainage system.
There are three major components of the pavement: the underlying surface, the base and cover, all together, they determine the stiffness of the coating. A hard surface made of concrete slabs, the joints between them filled with plastic sealant, which provides elasticity in the case of fluctuations of loads on the track. Not hard - cover "black gravel", i.e. a mixture of crushed stone or sand with coal tar or petroleum bitumen. Such coatings are called "tarmacadam" or "macadami with bitumen impregnation". Road surface bitumen also known as asphalt, and both versions (with Degteva and bitumen impregnation) is called the asphalt.
The coatings of both types of the underlying surface consists of compacted crushed stone or gravel. The basis of roads that are paved, usually concrete, and with unsteady from the "black gravel".

Agriculture

Agriculture
The modern agricultural machinery plays the important role in the production of food. Using these mechanisms one man can in a day to accomplish the scope of work, with which before mechanisation introduction could handle only whole brigade for a week.
Perhaps the most known representative of agricultural cars is the tractor created for the first time in the late nineteenth century to replace a horse. He didn't protect the tractor operator from the weather, and all conveniences were reduced to presence of an emphasis for feet and a rigid metal seat. Later there were seats on springs and the guards, which in some measure protected the driver from mud and dust, flying from under big driving wheels. But then nothing could save him from death or serious injury if the tractor overturned on a sloping plot of land.

The new design of tractors

The new design of tractors
In the beginning of 19b0 th years of the last century on tractors there were seats with pillows and similarity of cabins for creation of more comfortable working conditions of tractor operators. However, such cabs have been linked to another kind of inconveniences - noise. The covering from sheet metal like a sound pickup strengthened noise of the engine, transmission and hydraulic system to such an extent that it affected the health of the tractor operator.
Since then the cabin has changed significantly. New tractor cab protects the driver from weather, noise and overturning consequences. Almost all of them are Soundproofed, comfortable seats, heating and ventilation, windscreen wipers and a quick control.
The majority of tractors the engine and transmission form uniform rigid skeleton of all car and consequently there is no need for a separate frame. The engine power is from 15 to 190 kW and above, however, in tractors is approximately from 22 to 90 kW.
Usually on tractors the diesel set engines providing a drive on back or on all four wheels. In addition, engines rotate shaft of selection the capacities which are the reason for trailed implements or those that are mounted on the tractor, and also for the hydraulic systems that control these guns.
The basic agricultural tool, the plow. Its purpose is much like a shovel - flip to, to loosen and grind the top layer of soil, at the same time burying crop residues and weeds. In the modern mechanised agriculture a plough cling to a tractor though in many countries, as before, use a simple plough to which put horses or bulls.
Before to sow grain in the ploughed earth, you need to perform the final stage of the preparatory work. Just as the gardener uses the rake to prepare the ground for planting, the farmer uses a harrow for alignment of the ploughed earth and destruction of weeds.
One more kind of cars for preparation of soil and destruction of weeds - a cultivator supplied with steel teeths, or ploughshares for loosening the earth. The milling cultivator, whose tines or the blade are at the leading of the shaft, can be used for preparation of preliminary not ploughed soil.
Today many cultures sow by means of cars which loosen soil, put in it seeds on the set depth and through certain intervals and then covered it with soil. Such cars sow at once some numbers.

The harvest

The harvest
Now harvesting a variety of crops, including root crops (potatoes) and fruit (grapes and wine grades of apples) mechanized. One of the first and the most important machines of this type was the harvester, which is used during the harvesting of grain crops (wheat). This is a self-propelled combine which mows, separates grain from straw, removes the husk, the grain falls asleep in the truck that accompanies it, and dumps straw on the earth.
Straw is often classified as waste and believe that it fit only on a laying cattle or as the rough fodder additive for it.
Usually for transportation and storage straw is Packed in bales. This is done using solomokopnitel machines, towed by a tractor and pick up the straw left combines, press it in bales and knit a twine. The grass the same way you can knit in bales, and the received hay to store as a forage for livestock.
An important achievement in the field of processing of raw materials in agriculture in recent years was the introduction of "big bales", weighing about 500 kg. Machine can easily cope with them, allowing you to spend much less time cleaning straw from the fields. Solomokopnitel collects it, loads it into the chamber where it is Packed into bales, and then this bale ties with a twine and throws out.

Crop processing

Crop processing
After harvesting for its processing and storage require different machines, such as trailers, Vilkaste forklifts, conveyors and machines for separating potatoes from soil and stones. Potatoes are often harvested when the ground is wet, and if it is grown on rocky soil, the crop gets a large number of stones and lumps of earth. Wet soil can lead to rotting potatoes, and stones can beat, flaked or cut.
Potatoes can be separated from the earth by the sieve, through which sifted the earth. The stones can be removed manually, however, this transaction is expensive, given the costs of labor.
The possible decision is connected with use of x-rays. Harvest moving conveyor and, falling, passes through bunches of the x-rays that the difference in density between stones and potatoes. Upon detection of stones pnevmoshchup catches them, skipping the potatoes. Such technologies that save labour is widespread, as farmers try to maintain low prices 5 their products in a competitive environment.

Mechanical watch

Mechanical watch
The first mechanical clock appeared in Europe around 1275, however, the name of the inventor is unknown to us. Suspended on a cord cargo spun the wheel, it was put in action the mechanism of hours, which each hour the ting. Soon, in hours came hands and dial. Which showed time.
The important detail of hours - escapement device, which limits the speed of the mechanism through step-by-step rotation of the toothed wheel. A speed controller operates a timer that ensures the desired speed of the clock.
The course of antique mechanical clocks were regulated by a balance wheel, which consisted of a bar with counterweights on both ends, which was attached to a vertical rod. The rocker swayed in front of back, its vibrations are transmitted to the speed controller, and that regulated the speed of rotation of the mechanism.

Clock

Clock
About 1330 in Italy was a striking clock in which the number of blows corresponded to each hour. And around 1475, was invented by a clock-spring plant. This led to the development of portable watches that were impossible for machines with weights.
Until the XVI century. Watches had only one hour, to an arrow. Share hours can be determined only approximately. It worked for most people. However, the astronomers needed more accurate recording of their observations. The result is a watch with minute, and some even with a second hand. Watch, which was regulated by the folio, was inaccurate, but the accuracy of the computation time increased significantly with the appearance in the XVII century the pendulum clock.

Modern clock

Modern clock
Some modern stationary and watches are still manufactured with mechanical drive, however the electric and electronic watches have become the norm. In many electric clock move arrows provides a motor which works on AC current with frequency of 50-60 Hz. A similar principle of work and some digital electronic clock, but they show the time on a digital light Board. The electronic wristwatch needs its own regulator, and this role often plays the quartz crystal which provides a nearly constant frequency of vibration under the action of electricity. The vibrating crystal generates precise time the electrical impulses that control the display of electronic figures or movement of mechanical arrows. Most inpatient hours also work on quartz crystals.
Quartz watch gives a very high accuracy up to 1 /30 seconds per day, but that's yesterday's news compared to atomic clocks that use the frequency of radiation of atoms of some elements (e.g., cesium) and provide an electronic indication of time with an error of less than one second per thousand years. Such clocks are used in experiments that require accurate timing, and to determine the time: today the second is defined as the length of time for which an atom of cesium-133 emit of 9 192 631 770 impulses to certain specific conditions.

Accuracy of the pendular mechanism

Accuracy of the pendular mechanism
In 1580-e G. Italian physicist and astronomer Galileo Galilei (1564-1642) discovered, enhancing the isochronism of pendulum oscillations. A year before his death, he drew up a plan to use a pendulum to regulate clocks, and only in 1649 by his son Vincenzo and the mechanic at the name Balestri did finally watch Galileo. Subsequently, the perfect design of such a clock was developed by Dutch scientist Christiaan Huygens in the late 1650's, so the pendulum has proven itself reliable and accurate speed controller, and the daily error of standard hours has decreased from several minutes to ten seconds.
Another view of the regulator of the watch was created in 1658 when Robert hook invented the spring balance wheel or hair-spring. This thin coil spring was attached to the so-called balancer. Spring turns twisted and untwisted depending on the direction of motion of the balancer. This movement is allowed to operate a speed controller. The main advantage of the balance weight in comparison with the pendulum was the fact that his work was influenced much less by moving the watch. So it became possible to manufacture more smaller and more accurate pocket watches.
At the beginning of the XVIII century, new geographical discoveries and expansion of world trade resulted in a sharp increase in the number of long voyages. For successful sailing sailors needed an accurate method of determining the location of the own ship. The hardest part was to define a longitude - number of degrees East or West of the Greenwich Meridian. It needed an accurate timepiece showing the time in Greenwich mean time (England). But pitching courts stopped the pendulum and the clock with balance escapement was inaccurate in the extreme temperatures that adversely affected the work of the delicate hair springs.

Gregorian calendar

Gregorian calendar
First, the Julian calendar had no complaints, but gradually found that year lasts for 11 minutes less, than counted. This error was corrected in 1582 by Pope Gregory XIII, who decreed the day 5 October 15 Oct. Otherwise the calendar date more and more would not coincide with certain seasons. To exclude such error in the future, he also gave the order century years (at the turn of the century) to be leap-year only when they are divided by 400 without a remainder. This Gregorian calendar is still used in Western countries.
Night and day was the shortest periods of time known to our ancestors. A more accurate calculation of time appeared about 4000 p. n. e., when ancient Egyptians divided the time of day on the clock. The first timepiece was the sundial, consisting mainly of the column which is stuck into the ground so that it cast a shadow on the dial with hour divisions. When the sun moved across the sky, the shadow of the column moved on a scale and showed time.