The sieve is a tool made up of a hoop that has a mesh . This utensil is used to clean grains or seeds. By using the sieve, it is possible to remove unwanted solid substances that are mixed with the grains.
When the grains are passed through the sieve, the smaller elements are separated from the larger ones thanks to the mesh. This eliminates impurities that are not useful. When sifting wheat, for example, chaff can be excluded.
The holes in the screen mesh have different sizes according to their use. This characteristic depends on what is intended to be removed: if you want to remove dust, for example, the openings must be tiny.
The simplest sieve model is also known by other names, such as juera, sieve, sieve and sieve . Its ring is wide but shallow, and it is made of wood. As mentioned above, the sizes of the holes vary depending on the use of the tool, as well as the type of grain to be drilled. The material that is usually used for the bottom of the sieve is rawhide , and this is the part that is drilled.
In Spain, for example, there was a profession called hechador . These people had several sieves, each with holes of different sizes and arrangements, and they carried out their work for third parties. In short, the procedure consisted of taking the grain little by little, in small quantities that were easy to process, and resting the sieve against the waist and then making a side-to-side movement with the body, until finally they gave it to the grain. In a circular motion, they tilted it forward and pulled it away suddenly.
Far from being arbitrary, this coordinated movement managed to gather the unwanted parts lighter than wheat on the front edge of the sieve, so that when it was suddenly moved aside, raised and lowered, they fell to the ground while in the sieve the good grain remained. Needless to say, this task was difficult to master, as it required a lot of practice and precision, as well as great physical stamina to repeat it for several hours.
The idea of a sieve also has other meanings. In the field of botany , the partitions found in certain plant vessels are called sieve. These partitions have holes that are crossed by sap.
Screening, on the other hand, is a selection process that is characterized by its rigor. For example: “After four months of exams, I managed to pass the screening: I am now part of the National Institute of Technological Sciences” , “Those who manage to pass the screening will join the professional team” , “In this organization there is no screening, everyone is welcome" .
In the context of mathematics , sieves are algorithms used to factorize integers into prime factors. The Eratosthenes sieve and the Atkin sieve are some of these algorithms.
The algorithm called Eratosthenes' sieve allows us to throw out all the prime numbers that are below a given one, which must belong to the set of natural numbers (those that are used to count elements, that is, they are positive integers). You start with 2 and create a table that ends at said limit, which is represented by the letter n .
Atkin's sieve is based on Eratosthenes' sieve but offers a certain degree of optimization . It has the same objective as the previous one and avoids some steps, although it adds others.