The term "measure" refers to the evaluation of something. In the framework of metrology, this word has two different meanings. In the first case, we mean the creation of a designation for some unit. In the second, the measure is necessary in order to reproduce the unit value of the parameter.
General information
An indicator of a physical quantity is a means necessary for carrying out measurements. It is used to reproduce and store specified physical units. This may include, for example, a weight or measuring resistance. All over the world there is a single definition for the concept of "metrology". This is a branch of science that studies measurements, the methodology for combining them, and the rules for obtaining the required level of accuracy. The term "metrology" is derived from the words of the Greek language, which together mean "the study of measures."
Unity of Measurement
There are certain recording rules under which indicators are recorded in units accepted by law. Moreover, there are limits to the error of the results. Within this framework, indicators are considered acceptable. Therefore, various types of measurement errors are created that differ in the degree of deviation. The main task of the recording rules is to convert all the results obtained at different points, at different moments, using various instruments and methods, into a single system. Nowadays, it is necessary to obtain more accurate and reliable data in the fields of science and economics. Therefore, the types of measurements are so intensively studied. Metrology is of the utmost importance.
Measurement. Types of measurement
There are various interacting operations whose task is to establish the types of relations between the value that is estimated and the one that is considered a unit. The latter is fixed in the device for measuring. The numerical value is the data received. They have another name - an indicator of physical quantity. There are various types of measuring instruments. These include the units themselves, and devices, and special converters, as well as systems and installations. Vastly and the meaning of the concept of "dimension". The types of measurement are also very diverse. However, there are some common points. Types and methods of measurements are united by one structure. Assessment procedures consist of two stages. First of all, you need to compare the measured value with the reference unit, and then convert it to the desired format by contacting a specific method.
Variability
A variety of different types of measurements differ. The classification of devices for this procedure also implies the presence of different sections. Accepted systematization for the intended purpose, for example. One group of devices is called exemplary, and the other - workers. The former are necessary in order to use them as a reference for checking the accuracy of other measurements. Workers include those that are designed to assess the size of specific quantities used by man. We can say that the meaning of this classification is not in the accuracy of the instruments, but in differences in purpose. There are various means by which measurement is carried out. Types of measurements also include special measures by which they reproduce any value of a specific size.
Unambiguous and ambiguous measures. Differences
There are also unambiguous and ambiguous measures. The first ones are those that are capable of showing only quantities with the same size. With multi-valued playback sequences of various sizes are available. Such a measure can be called, say, a millimeter ruler. There are also peculiar sets that are formed from various sets of measures. They recreate intermediate and total values. In addition, interacting measures can carry out common work, and each can act separately. In order to compare the value with the measure, you must use a special device - a comparator. In the role of this tool are often equal arms and measuring bridge.
If we study the unambiguous measures in more detail, we can say that they also include samples and substances that play this role. They have a specific composition and properties. The slightest deviations are unacceptable. Such reference substances can help assess roughness, hardness, and identify any other material properties. Samples help create points that form scales. Zinc and gold, for example, are used when you want to recreate a certain temperature.
Discharges
The estimation error classifies all measures into several consecutive digits. In the case of deviations from the standard of the measures themselves, a class division is formed. Units of a certain category check the errors of measuring instruments, due to which they are ranked as samples.
Converters. General information
A device for measuring, which generates from the information obtained after measurement information such data that it is possible to convert, store and process, but does not open visual access to them, is called a measuring transducer. What is its action? Let's consider it in more detail.
The essence of the transformation
When a quantity is only being prepared for processing, it is called an input value. And the information received is called "output". The converter-amplifier is such a device that does not change the physical state of the processed data, and the conversion has the form of a linear function. The term “amplifier” is used in conjunction with a word explaining its effect. For example, "voltage amplifier." If during the conversion the value is converted to another, then the device receives the name from the new value - "electromechanical".
Transducer Types
Depending on which part of the device it is located in, the converter may be primary. This means that the measured value passes immediately through it. It can be transmitting. In this case, the values occur after processing. The converter can be intermediate. It is located after the primary.
Devices. General information
Measuring instruments are considered to be such means of obtaining data on a quantity that represent them in a format accessible for visual examination. Depending on the type of assessment, they are grouped into specific groups. So, the most common are devices that conduct direct measurements. Their feature is that they convert the source data without leaving information about their initial state. There are also devices with the help of which indirect measurements are also carried out.
Comparison Devices
However, devices with direct action are not the most accurate. This characteristic is much higher for the comparison device. His work is based on a comparison of the data obtained by measuring the studied quantity with already known information about other values. This method is called "indirect measurements". Their receipt is possible in the presence of source data. In other words, the parameters are formed from indicators that give a direct measurement. Measurement types have several more categories. In order to compare values, it is necessary to use compensation or bridge chains. The first to compare those quantities that have some energy or strength. This method is based on the fact that the compared values are connected to the circuit and study their manifestation. In the same case, if the value is considered passive, that is, it has resistance, bridge circuits are used.
Reference Distribution
Instruments have various methods of reading data for the studied quantities. Therefore, a special classification was created. Based on it, we can conclude that there are reproducing devices, which include not only analog, but also digital. Another type of device is the one that records information. The most popular are analog devices. Their component, responsible for reference, is formed of two parts. The first is the scale, which is connected to the moving part. Another element of the device is a pointer connected to the body of the device. The action of meters, the operation of which is based on the digital principle, is the result of mechanical and electronic elements.
Variation in recording method
There is another classification of recording devices. For example, by the method by which the data of the registration device is recorded. There are recorders, as well as printing. The former provide the received and processed information and aggregate measurements in the form of graphs, charts, and diagrams. The registrars, working on the second principle, give the results of work on a paper tape, converting them into numbers. Very often there are devices that work according to the comparison model, which are a combination of all the above types, that is, they are a combination of the readout on a scale and a digital technique. Data registration, processing and printing can be done both in the form of graphs with charts, and a series of digital values and numbers.
Auxiliary elements of assessment
There are also auxiliary instruments and means for taking measurements. The peculiarity of such devices is that they not only conduct research on quantities on their own. They can regulate the operation of the main element, changing its effect at the time of reading information, as well as during its processing or output. Data that is provided by additional means helps to control and edit the readings of devices. For example, for clearer operation of thermometers, it is also necessary to install pressure gauges that measure the ambient pressure. In addition, auxiliary devices can change the settings of the meter. So, in the case of using the device to register the humidity level, you need to set the range values.
Setting
There are situations when, in order to obtain more accurate measurement data, one device is not enough. In this case, complex installations are assembled, consisting of devices for various purposes. They are located in a certain sequence in a limited area. Some of the devices used convert the aggregate measurements into a single system. It is provided to the observer responsible for collecting, organizing and processing information.
Systems
At a different level are measuring systems. The difference between such complexes and the above-described installations is that they can be scattered over vast territories, and communicate through special information channels. Data in such systems is provided in two forms. One of them is more accessible for a real person studying the results of work. The processing of another is done by a computer.
Indicators
There are devices whose task is to read the manifestations of physical properties. They are called indicators. Even from the school chemistry course everyone knows litmus papers related to indicators. The compass needle is also considered such a device. Moreover, a meter that displays the level of fuel in an automobile gas tank is also an indicator.