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iple of separation , some of these fibers may be from the suspect or the victim scraped or rubbed on clothing under the single fiber , there may be under tow hooks , often attached to the tools of crime , import and export of weapons and other obstructions or carrier , in general, these split down the slim and short .

Detached from the whole slender and short fibers remained of the original overall physical and chemical properties and fiber , so the overall separation adapt the same identification . Although the fiber due to wear , washing and environmental factors, some of the physical parameters to change, but on the whole for the same fiber , which is still the same physical parameters , are separate traces for the same identification .

Natural or synthetic fibers are thin filaments , textile fibers refers to a fiber spinning and weaving . A wide range of textile fibers , according to their sources can be divided into two categories : the natural fiber and chemical fiber . Natural fibers are grown in the presence or nature of the fiber, which can be divided into plant fibers ( seed fibers, bast fibers, leaf fibers , fruit fiber ) , animal fiber ( fibrous and glandular hair fiber ) and mineral fibers ( various asbestos ) ; chemical fibers are natural or synthetic substances as raw fibers obtained , is divided into recycled fibers, synthetic fibers and inorganic fibers. Common fibers : silk fiber, silk , castor silk , wool, alpaca , angora , cashmere, camel cashmere, mohair, yak , cotton, kapok , Xuan cotton, flax, jute , hemp, kenaf , Apocynum , viscose fiber , acetate fiber, copper and nitrogen fiber, polyester, nylon, acrylic, polypropylene , polyvinyl alcohol , polyvinyl chloride , nitrogen Lun , aramid .

By comparing the characteristics of the body in order to reflect the identification of two ( or more ) reflects the characteristics of the body are derived from the same object in a way. Is a person with expertise being sought by the characteristics of the object reflecting body and reflect the characteristics of the object under examination body for comparison test to determine the object being sought and whether the same object under review scientific activities .

Normal distribution (normal distribution) , also known as the Gaussian distribution (Gaussian distribution), is one in mathematics, physics and engineering are very important areas such as probability distributions , statistically many aspects have a significant influence. If the random variable X follows a mathematical expectation , standard deviation of the Gaussian distribution , denoted as : then its probability density function is normal expectation μ determine its location , and its standard deviation determines the distribution of the amplitude. Its bell-shaped curve , so people also often called bell -shaped curve.

Standard deviation (Standard Deviation), the most commonly used in probability and statistics as a statistical distribution level (statistical dispersion) on the measurements. Standard deviation is defined as the square root of the variance , between individuals within the group reflect the degree of dispersion . The degree distribution of the measured results .

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