It is difficult to overestimate the importance of measurements in the life of a modern person. As technology develops, the question of the need for them is not at all, but the principles and methods that make it possible to increase the accuracy of measurements come to the fore. The range of areas in which measurement systems and methods are used is also expanding. At the same time, not only technical and technological approaches to the implementation of these operations are being developed, but also the concepts of their application. To date, the measurement method is a set of techniques or techniques that allow you to implement one or another principle for determining the desired value.
Principles of measurement methods
The basis of any measurement method is a certain physical law, which, in turn, is based on a particular natural phenomenon. In metrology, physical phenomena are often defined as effects that cause a pattern. Specific laws apply to measure different quantities. For example, the measurement of current is made by the Josephson effect. This phenomenon, according to which the superconducting current passes through the interlayer of dielectrics,separating superconductors. To determine the characteristics of the absorbed energy, another effect is used - Peltier, and to calculate the speed - the law of change in the radiation frequency, discovered by Doppler. A simpler example of determining the mass of an object uses gravity, which manifests itself in the process of weighing.
Classifications of measurement methods
Usually, two signs of separation of measurement methods are used - according to the nature of the change in values depending on time and according to the method of obtaining data. In the first case, statistical and dynamic methods are distinguished. Statistical methods of measurement are characterized by the fact that the result obtained does not change depending on the moment at which they are applied. These can be, for example, the main methods for measuring the mass and dimensions of an object. Dynamic techniques, on the contrary, initially allow for the possibility of fluctuations in performance. Such methods include those methods that allow you to track the characteristics of pressure, gas or temperature. Changes usually occur under the influence of environments. There are other classifications of methods, due to the difference in measurement accuracy and the conditions of the operation. But they are usually secondary. Now it is worth considering the most popular measurement methods.
Measure comparison method
In this case, the measurement occurs by comparing the desired value with the values reproduced by the measure. An example of this method is the calculation of the mass withusing lever-type scales. The user initially works with the tool, which contains certain values with measures. In particular, using the system of balancing with weights, he can fix the weight of an object with a certain degree of accuracy. The classic pressure measuring device also, in some modifications, involves determining the value by comparison with readings in an environment in which initially known values already operate. Another example concerns the measurement of voltage current. In this case, for example, the characteristics of the compensator will be compared with the known electromotive force of a normal element.
Measurement method by addition
Also a fairly common technique that is used in a variety of areas. The method of measuring the value of the addition also provides for the desired value and a certain measure, which is known in advance. Only, unlike the previous method, the measurement is made directly when comparing not with the calculated value, but under the conditions of its addition with a similar value. As a rule, methods and measuring instruments according to this principle are more often used in working with physical indicators of the characteristics of an object. In a sense, this technique is similar to the method of determining quantities through substitution. Only in this case, the correction factor is provided not by a value that is similar to the desired value, but by the readings of the reference object.
Organoleptic measurement method
It's prettyan unusual direction of metrology, which is based on the use of human senses. There are two categories of organoleptic measurements. For example, the element-by-element method makes it possible to evaluate a specific parameter of an object without giving a complete picture of its characteristics and possible operational qualities. The second category represents an integrated approach, in which the method of measurement with the help of the senses gives a more complete picture of the different parameters of the object. It is important to understand that complex analysis is often useful not so much as a way to take into account a whole group of characteristics, but as a tool for assessing the overall suitability of an object in terms of possible use for a specific purpose. As for the practical application of organoleptic methods, they can be used to evaluate, for example, the ovality or cut quality of cylindrical parts. In a complex measurement by this method, you can get an idea of the radial runout of the shaft, which will just be detected after analyzing the same ovality and characteristics of the outer surface of the element.
Contact and non-contact measurement methods
The principles of contact and non-contact measurement have a significant difference. In the case of contact devices, the value is fixed in close proximity to the object. But, since this is not always possible due to the presence of aggressive media and difficult access to the measurement site, the non-contact principle of calculating values has also become widespread. The contact measurement method is usedin determining such quantities as mass, current, overall parameters, etc. However, when measuring extremely high temperatures, it is not always possible.
Non-contact measurement can be performed with special models of pyrometers and thermal imagers. During operation, they are not directly in the target measurement environment, but interact with its radiation. For a number of reasons, non-contact temperature measurement methods are not very accurate. Therefore, they are used only where you need to have an idea about the characteristics of certain zones or areas.
The range of measurement tools is very extensive, even if we talk about a specific area separately. For example, to measure temperature alone, thermometers, pyrometers, the same thermal imagers and multifunctional stations with the functions of a hygrometer and barometer are used. Recently, loggers equipped with sensitive probes have been used in the complex to record humidity and temperature readings. When assessing atmospheric conditions, a manometer is also often used - this is a device for measuring pressure, which can be supplemented with sensors for monitoring gaseous media. A wide group of devices is also represented in the segment of measuring instruments for the characteristics of electrical circuits. Here you can select devices such as a voltmeter and an ammeter. Again, as in the case of weather stations, the means for taking into account the parameters of the electric field can be universal - that is, taking into account several parameters at the same time.
Instrumentationinstruments and automation
In the traditional sense, a measuring device is a tool that provides information about a particular value characteristic of a particular object at a given moment. During the operation, the user registers readings and subsequently makes appropriate decisions based on them. But more and more often, these same devices are integrated into a complex of equipment with automation, which, based on the same recorded readings, independently makes decisions, for example, on correcting operating parameters. In particular, instrumentation and equipment automation are successfully combined in gas pipeline complexes, in heating and ventilation systems, etc. gas.
Measurements and uncertainties
Almost every measurement process involves some degree of variation in the reported results relative to the actual values. The error can be 0.001% or 10% or more. In this case, random and systematic deviations are distinguished. The random error of the measurement result is characterized by the fact that it does not obey a certain pattern. Conversely, systematic deviations from actual values differ in that they retain their values even after numerous repeated measurements.
Manufacturers of measuring instruments and highly specialized metrological equipment are striving to develop more functional and at the same time affordable models. And this applies not only to professional equipment, but also to household appliances. For example, current measurement can be carried out at home using a multimeter that records several parameters at the same time. The same can be said about devices that work with readings of pressure, humidity and temperature, which are endowed with wide functionality and modern ergonomics. True, if the task is to register a specific value, then experts still recommend using special devices that work only with the target parameter. They tend to have higher measurement accuracy, which is often crucial in evaluating the performance of equipment.