Weighing a load on a scale is a measurement. The Truth About Truck Axle Loads. How and why are axle loads measured? Units of strength. The relationship between gravity and body mass

Error-free measurement and timely registration of weight and dimensional characteristics (WGC) of goods at different stages of their processing are extremely important for the highly efficient operation of any warehouse. VHC form the basis for calculating such important parameters as, for example, optimal use of warehouse space, maximum load Vehicle(TS) and, most importantly, error-free shipping billing by transport companies. Neglect of such information or errors during the measurement phase can lead to increased operating costs or lost profits.

Advantages of using automatic VHC measurement systems

Automated measurement systems (AIS) of VGH cargo differ in the size of the measured cargo, throughput, installation options, and can allow the measurement of the cargo in statics or while moving along the conveyor.

Potential customers of AIS VGH are logistic and transport companies, distribution centers, safekeeping warehouses, distributors, 3PL and 4PL operators and manufacturers of oversized goods.

Let us dwell in more detail on the main applied logistic and warehouse tasks, solved with the help of static, dynamic and portal AIS VGH cargo.

Usually, the question of modernizing warehouses arises when it is necessary to increase their throughput without using additional areas. Modernization of warehouses using automated systems in such precision processes as VHC measurement, along with the use of conveyor and sorting lines, it can significantly increase the capacity of the warehouse.

Systems for automatic registration of VHC in the receiving area allow:

instantly identify the cargo;
get rid of manual data entry, which gives an increase in overall productivity;
automate the billing process;
get rid of various operational errors, including theft problems.

Determination of under-investment and excess of goods in the shipment area is carried out by comparing the actual volume and weight of the shipped goods and their program counterparts... Full compliance between the order and the goods shipped to the customer is one of the priority tasks for companies working in the intralogistics field, and allows you to maintain a reputation as a reliable supplier.

Combined use of AIS VGH and analytical capacities of warehouse management systems (Warehouse Management System, WMS) in a warehouse allows:

ensure optimal cargo turnover;
optimize the filling of the vehicle, exclude its overloading and plan the safe transportation of oversized cargo;
to increase the useful area of the warehouse (for example, to unload warehouse spaces, it is first of all advisable to export bulky goods);
optimize storage (in order to exclude, for example, the crush of the cargo and its hanging from the pallets, etc.).

In addition, the customer of the system receives a visual display of the warehouse loading online, including the receipt / consumption of goods and the loading of each vehicle.

Review of systems for automated measurement of VHC cargo

AIS VGH differ depending on the size and shape of the cargo, for example: only cubic objects; pallet; objects of any shape (table).

The range of systems is in a wide cost range, and the availability of additional options and wide choose installation options (ceiling, wall, free-standing, mobile) allow you to choose a solution for any logistic problem. Let us consider the capabilities of the AIS VGH presented in the table in detail.

Measurement of loads in static

Sensotec VolumeOne (Russia)

Rice. 1. Sensotec VolumeOne

The industrial SENSOTEC VolumeOne system (Fig. 1) has proven itself to be a stable system for measuring the VHC of cubic weights. In the current economic situation in the country, the shift in emphasis towards Russian production allowed it to occupy the niche of the most budgetary solution in the domestic market.

SENSOTEC VolumeOne is designed for manual cargo acceptance and can be easily integrated into analytical control systems. The sender places the cargo on the measuring table, and the system automatically reads the barcode, processes it and the system automatically processes and transfers the received data to the WMS. The system collects the following analytical data: total number of measurements; number of erroneous measurements; system load schedule during the day; specific time for measurements; productivity, etc. Connection is carried out via RS-232, power supply - from a 220 V network or a battery (12 V).

Additional modules and capabilities of SENSOTEC VolumeOne:

I / O port for connecting a label printer;
wireless connection of the barcode reader (Bluetooth);
color HMI-panel for autonomous operation;
display of information about the battery charge;
indication of the system operation status;
sound signaling about system overload.

Today, the main consumers of the system are online shopping, wholesale and retail warehouses, shipping companies, forwarding and courier services.

Rice. 2. ExpressCube 165R

ExpressCube 165R / 265R, ExpressCube 480R (Canada)

The ExpressCube 165R systems (Figure 2) have proven to be an economical solution for measuring small-scale VHC. The modes of operation are via a local control system (ExpressCube controller) and an external PC, which allows the ExpressCube to be integrated into an existing WMS.

Additional technical characteristics:

measurement time - 2 s;
measuring principle - photoelectric;
connection - USB, Serial (RS-232, RS-422);
visualization of results - LCD-screen (optional);
food - 95–250 V alternating current, 50-60 Hz;
operating temperature range –10… + 40 ° C.

APACHE Parcel 510/520 Static (Germany)

APACHE Parcel 510/520 Static systems from AKL-tec have an average throughput up to 500 units of cargo per hour and provide all the necessary data for cargo calculations or registration transport documentation at the touch of a button. Each system consists of a VHC laser scanner, a rugged static weighing system and hand-held barcode readers, all housed in a robust mechanical case.

The principle of operation of the systems is as follows. A scanning head mounted on a linear axis with a built-in evaluation function moves over a stationary object, measures it, forms a scanning plane and, due to linear movement along the object, obtains its three-dimensional model and provides information about the length, height and width of the cuboid weight. This allows you to reliably determine the dimensions of loads with dimensions of at least 50 × 50 × 50 mm.

The principle of operation used in the system ensures its high reliability. So, for example, a deviation from the horizontal by ± 5 ° will not lead to erroneous readings. The entire measurement process is started when the barcode is scanned on the object. As soon as the hand-held scanner reads a valid code, the system uses the weighing result to drive the linear axis and measure the volume of the object.

APACHE systems can be equipped with one scanner (510 Static) for measuring cubic objects, and two scanners (520 Static) for measuring irregular objects.

Integration is carried out via the AKL APACHE Cubidata software module. The compact controller supports RS-232, TCP / IP, ODBC, XML, etc.

Dynamic load measurement

APACHE Conveyor Checker, Parcel Conveyor and APACHE Conveyor

Conveyor systems for measuring dimensions and weight AKL-tec (Germany) determine the VHC and the volume of packages of arbitrary shape in motion, without stopping the conveyor. The optional APACHE function also allows you to take photographs of a subject. During the movement of an object, its full 3D image is created, which is used by the volume determination system (VMS), and also used to determine other basic characteristics of goods, such as their length, width, height and actual volume.

Systems can be equipped with :

one laser scanner with visible red light 650 nm (APACHE Parcel Conveyor Checker) for measuring cuboid objects only;
two scanners (APACHE Parcel Conveyor) for measuring objects of arbitrary shape;
two infrared scanners for measuring palletized cargo (APACHE Conveyor).

Cargo identification is performed by manual or automatic barcode reading, as well as using transponders (RFID) or direct connection to the conveyor control system.

After measurement and registration by the APACHE system, the obtained data is transmitted to analytical warehouse management systems for further processing through the appropriate interfaces. Is the data logging performed continuously at the speed of movement of the goods? 2 m / s (APACHE Conveyor Checker) and? 3 m / s (APACHE Parcel Conveyor). Integration - with standard pallet conveyors, floor-standing continuous conveyor systems using low-lift platform lifters.

Portal cargo measurement systems

APACHE Portal

Rice. 3. Measurement of VHC using the Apache Portal movable system

The APACHE Portal system is a cargo checkpoint equipped with volumetric measuring, weighing and photographing devices. The system is available in a stationary (APACHE Portal) or mobile version (Apache Portal movable, Fig. 3), or in a MULTI-ZONE version (measurement zones can be freely selected, and loads on them can be processed independently of each other).

The principle of operation is as follows. The cargo moves to check Point with a forklift, pallet truck or electronic forklift. Then the load is placed on the weighing platform, where it is subjected to complex measurements by the APACHE Portal system due to two infrared scanners installed above the load, moving on two linear guides. The movement is monitored using an incremental displacement encoder. A gapless scan is performed throughout. VHC of an object, as well as its photographs, are automatically displayed, saved and documented. It is possible to measure only opaque objects and objects with constant dimensions / shape.

A wide range of installation options (ceiling, wall or free-standing), ease of use and the availability of additional software and hardware modules, as well as specially designed interfaces for external systems guarantee the successful integration of ARACNE Portal into any warehouse management system (WMS).

The charter of inland waterway transport requires a mandatory definition and indication of the mass of the consignment in the consignment note when accepting it for carriage. This is necessary in order to establish exactly how much cargo is accepted and must be handed over to the recipient, which makes it possible to establish the responsibility of the transport for the safety of transportation, correctly calculate freight charges, rationally use the carrying capacity of ships and the cargo capacity of warehouses, as well as for quantitative accounting of the performed transportation.

Methods for determining the mass of a consignment

So that there are no liberties in resolving this issue, the procedure and methods for determining the mass of a consignment of goods are established in Articles 64-66 of the "Charter of Inland Water Transport".

In accordance with the norms, all methods are divided into 3 groups:

determination of the mass of a consignment by weighing;
by calculation methods;
at the request of the sender.

The choice of method is influenced by a number of factors:

type of cargo;
type of container;
way of transportation;
belonging of the berth where the cargo is accepted for transportation.

It should be noted that when choosing a method, the basic principle must be observed: the mass of a consignment must be determined in the way that it can be determined at the point of destination or transshipment from one mode of transport to another. This is due to two factors.

First, the method for determining the mass of a consignment at the point of departure and destination should be the same. Only under this condition can one judge the presence or absence of partial loss of cargo along the way, because different methods of determining the mass may not give identical results, which will lead to claims from the cargo owner.

Secondly, the port of departure chooses a method based on the technical capabilities of the port of destination. This is determined by the fact that the ports of destination, as a rule, are peripheral and their technical capabilities are lower than the technical capabilities of the ports of departure.

Determination of the mass of a consignment by weighing

Weighing- the most accurate and most expensive method for determining the mass of a consignment of cargo, increasing fleet downtime by 15-20%. In accordance with Art. 50 UVHT, to determine the mass of cargo on the berths of general and non-public use, required amount scales installed at the side of the vessel, and on elevators - in the chain of mechanization of reloading operations.

This method is used in all cases of transportation of grain cargo (except for those transported in a standard container), salt transported in bulk, coal and other bulk cargo, when transporting mass, when there is doubt about the correctness, and in some other cases. The mass of a consignment of cargo is determined by weighing in all cases if loading is carried out at non-public berths, and by the port, if cargo is received and loaded at public berths.

Transport organizations have the right (Art. 65 UHVT) to check the weight of the cargo, determined by the consignor. In the case when cargo is accepted for carriage, which must then be transferred to another transport with a check of the mass, then such a right becomes the responsibility of the carrier.

Various kinds of scales can be used for weighing: commodity, automobile, wagon, bunker. The choice of weights for each berth is determined by the technical equipment and transportation rules. The number of scales for each berth is determined by calculation, depending on their performance. The permissible weighing error should be no more than 0.1%.

It should be noted that when determining the mass of cargo by weighing, the basic principle must be observed: the scales at the point of departure and destination must be of the same type. This is due to the fact that different types of scales give different errors.

Since weighing is a laborious and expensive method, therefore, in practice, calculation methods for determining the mass of the cargo are often used.

Determination of the mass of a consignment according to the standard mass of individual packages

Until 1956, the mass of a consignment was determined for all goods by weighing only. Since 1956, work has been carried out to standardize packaging, and therefore some types of products are produced in packaging of standard weight (sugar, flour, cereals, etc.). According to article 65 of the UHHT, goods in standard weight packaging are not weighed when they are accepted for carriage. The mass of a consignment is determined as the product of the mass of one package by the number of packages.

Q n = N n q cm, kg,

where Q n is the mass of the consignment, kg;
N n - the number of pieces in the consignment, units;
q cm - standard mass of one package, kg;
An entry is made in the invoice: “According to the standard”.

By stencil or non-standard weight of individual packages

When the cargo is transported in non-standard containers (shoes, clothing, equipment, machines, etc.), then the mass of the consignment is determined as the sum of the mass of each piece.

Q n = ∑ q i tr. , kg,

where q i tr. - the mass of each piece, applied with paint directly on the container or on various tags attached to each piece of cargo.

In the transport documents in the column “name of the cargo” a list of goods is given and their mass is indicated, then the total mass is summed up and recorded in the column “mass of the batch” and a mark is made: “By stencil”.

By the conditional mass of individual cargo items

The mass of some specific cargo (cars, furniture, animals, plants, etc.) is accepted for transportation without weighing according to the conditional mass of individual cargo items. This is due to the fact that it is not advisable to determine the actual mass of this category of goods due to their relatively small mass with a significant occupied volume, and also due to the fact that during transportation their mass decreases (animals).

The conventional weight is greater than the actual weight, and thus allows you to get increased carriage charges corresponding to the actual cost of transportation of these goods.

So that there is no arbitrariness when determining the mass of a consignment of cargo by this method, the conditional mass is determined and approved in Appendix No. 5 of the price list 14-01. Formula for determining the mass of a consignment:

Q n = n q conv. , kg,

where q conv. - weight of one piece, kg;
n - number of places, units;
The transport documents write “conditionally”.

Determination of the mass of the consignment by measuring the stacks

Measurement and average density (bulk density) determine the mass of bulk and timber cargo. As a result of measuring the stack, the volume of the stack is obtained. Measurement can be carried out both onshore and in the hold of the vessel. The mass is determined by multiplying the volume of the stack found as a result of the measurement by its bulk mass.

Q n = V γ, kg,

where γ is the density of the cargo, t / m 3;
V is the volume of the stack, m 3.

The conversion of volumetric measures into mass measures for individual types of cargo is given in Appendix No. 6 of the price list 14-01.

When determining the mass of timber cargo, 1 m 3 of solid wood is taken as the volumetric measure of round timber and sawn timber, and a fold cubic meter is taken as the volumetric measure of the balances of the mine rack and firewood.

If the volume of timber cargo is set in solid wood, then their mass is determined by the formula:

Q p = γ pl · V pl. , T,

where γ pl is the density of dense wood t / m 3;
V pl - the volume of dense wood, m 3.

If the volume of timber cargo is set in a foldable measure, then their mass will be determined by the formula:

Q p = K sc: γ pl V sc, t,

where K skl = 0.64 is the conversion factor of folding cubic meters into cubic meters of dense wood;
V skl - fold volume of wood, m 3.

If raw wood and firewood, fused during the current navigation and loaded into the ship from the water, roundwood and sawn timber after October 1 of the previous year are presented for transportation.

When transporting sand and sand and gravel mixture in vessels adapted for hydro-mechanized loading and unloading, the mass is determined based on the average height of the empty part of the bunker; make ten measurements from the edge of the bunker to the surface of the cargo (h i) on each side at regular intervals:

h with р = 20 Σ h i i - l 20, m

The height of the load and its volume can then be determined.

h r = h σ - h mean, m,

where h σ is the height of the bunker;
h r - cargo height, m;
In traditional documents, in the column “method of determining the mass” is written “By stack measurements”.

By the draft of the vessel

This method determines the mass of bulk and bulk cargo (except for grain, the mass of which is determined by weighing). In this case, two methods of determining the mass are used: according to the table of the load size or the load scale and the calculated one.

For this purpose, the average draft of the vessel is determined. The draft is measured at six points: three points on the port side (bow, middle, stern) and three on the starboard side. The average draft is determined by the formula:

T c p = T n l. b + 2 T with r l. b + T to l. b + T n p. b + 2 T s r p. b + T c p. b 8, m

where T n, T cf, T k - draft of the bow, middle and stern, respectively, for the left and right sides, m.

In order to more accurately determine the mass of the cargo consignment, the draft of the middle part of the vessel, where the largest amount of cargo is located, is doubled.

Proceeding from the average draft of the vessel in laden and unladen condition, the mass of the loaded cargo is determined according to the schedule of the cargo size or according to the cargo scale.

The mass of the consignment, Q n, will be equal to:

Q n = Q 2 - Q 1, t,

Where Q 2 and Q 1 - loading of the vessel in cargo and unladen, t;
T 0, T gr - register values of the sediment, m;
₸ 0, ₸ gr - average value of sediment, m;
Q p - register carrying capacity, t;
In this case, the value of Q 1> 0 indicates that the ship may have ballast, fuel, drinking water etc.

If there is a cargo scale for the ship, then the mass of the consignment is determined from it.

The cargo scale is the passport characteristic of the vessel and is presented in the form of a table.

In cases where the ship does not have a load size chart or load scale, the mass of the lot can be determined by calculation. The basis for determining the mass of the loaded (unloaded) cargo by the draft of the vessel by calculation is the principle of the difference between the displacement of a vessel with cargo and unladen.

Q n = D gr - D o, t,

where D gr, D o - displacement in cargo and unladen, i.e.

The displacement of the vessel is determined by the formula:

Д с = γδ L BT, m,

where L is the length of the vessel, m;
B is the breadth of the vessel, m;
T is the draft of the vessel, m;
δ - coefficient of displacement completeness is defined as the ratio of the volume of the underwater part of the vessel to the volume of the parallelepiped, which describes the underwater part of the vessel;

γ is the density of water, t / m 3;
γ = 1- for fresh water;
γ = 1.003-1.031 - for salt water (varies depending on the sea basin).

Based on this, the mass of the consignment will be equal to:

Q n = δγ LB (T gr - T 0), i.e.

This formula is valid for determining the mass of cargo when transported in a basin with the same water density by vessels with contours that do not change in height or when the vessel is loaded to full capacity. In relative cases, it is necessary to take into account the change in the coefficient of displacement and water density. Then the formula will take the form:

Q n = LB (δ gr γ 2 T gr - δ o γ 1 T 0), t,

where δ gr, δ o - the coefficients of the fullness of the displacement in cargo and unladen;
γ 2, γ 1 - density of water at the point of loading and unloading, t / m 3.

When determining the weight of the cargo by draft, it is necessary to take into account the change in the reserves of fuel, ballast, drinking water, etc. during transshipment operations. The formula will be:

Q n = (D gr - ∑q gr) - (D 0 - ∑q 0), t,

where ∑q gr, ∑q 0 is the amount of fuel, drinking water and ballast reserves before and after loading.

When determining the mass of cargo by the draft of the vessel, the most laborious and not always accurate enough is the process of measuring the draft of the vessel (excitement).

In transport documents it is written: "By draft".

Determination of the mass of a consignment of goods transported in bulk vessels

The mass of a consignment can be determined in three ways:

onshore tank calibration tables;
by calculation;
according to the cargo tables of ships.

The first way is the easiest. The height of the low tide in the tank before and after loading is found, for each the volumes are determined according to the calibration tables and the difference of which will give the volume of the cargo loaded into the ship. Then the mass of the consignment will be equal to:

Q n = V n γ n, t,

V n - the volume of oil, m 3;
γ n - density of the oil product, t / m 3.

In the absence of calibration tables of onshore cylindrical tanks, the mass of oil products can be obtained by calculation:

Q n = πR 2 hγ n, t,

where R is the radius of the tank, m;
h - loading height, m;
γ n - density of the oil product, t / m 3.

This method is used in cases where the distance from the coastal reservoirs is not more than 2 km; if more than 2 km, then this method is prohibited to use (losses in pipelines).

In the absence of calibration tables of onshore tanks or when these tanks are located more than 2 km from the vessel, the mass of the consignment can be determined from the cargo tables of the vessels.

The essence of the method is as follows: the loading height in all the tanks of the vessel is measured before and after loading, then the volume in each tank is determined, multiplied by the density of the corresponding cargo, and the obtained values are summed up. Thus, the total mass of the cargo loaded into the ship is found.

Determination of the mass of the consignment at the request of the consignor

This is the easiest of all methods. It is used to determine the mass of low-value bulk cargo.

The consignor is responsible for the correct determination of the mass of the consignment. At the point of destination, the cargo is released without checking the weight. However, you need to pay attention to the following points:

if the shipper incorrectly stated the mass of the cargo, then according to Art. 198 UHVT, a fine is charged from him according to the tariff (in the amount of double the carriage charge charged for an unspecified amount of cargo). In addition, a carriage charge is charged for an unspecified amount of cargo;
if, as a result of an incorrectly indicated mass, an accident occurs, then, in addition to the above payments, the cargo owner pays all the costs of eliminating the accident.

In the transport documents it is written: “According to the application of the sender”.

3. Stereotyped work movements (number per shift,

total for two hands)

The concept of "labor movement" in this case means elementary movement, i.e. a single movement of the hands (or arms) from one position to another. Stereotyped working movements, depending on the range of motion and the muscle mass involved in the performance of the movement, are divided into local and regional. Work, which is characterized by local movements, as a rule, is performed at a fast pace (60 - 250 movements per minute), and per shift the number of movements can reach several tens of thousands. Since during these works the pace, i.e. the number of movements per unit of time practically does not change, then, having counted the number of movements in 10-15 minutes using some automatic counter, we calculate the number of movements in 1 minute, and then multiply by the number of minutes during which this work is performed ... The time of work is determined by time-keeping observations or from a photograph of the working day. The number of movements can also be determined by the number of characters printed (entered) per shift (we count the number of characters on one page and multiply by the number of pages printed per day).

Example 1. An operator entering data into a personal computer prints 20 sheets per shift. The number of characters on 1 sheet is 2720. The total number of characters to be entered per shift is 54400, i.e. 54400 small local movements. Consequently, according to this indicator (clause 3.1 of the Guidelines), his work is classified as class 3.1.

Regional labor movements are usually carried out at a slower pace and it is easy to count their number in 10-15 minutes. or for 1 - 2 repeated operations, several times per shift. After that, knowing the total number of operations or the time to complete the work, we calculate the total number of regional movements per shift.

Example 2. The painter performs about 80 large-amplitude movements per minute. In total, the main work takes 65% of the working time, i.e. 312 minutes per shift. The number of movements per shift = 24960 (312 x 80), which, in accordance with paragraph 3.2 of the Guidelines, makes it possible to classify his work as class 3.1.

Amplitude Frequency Response (AFC)

Frequency response - (abbreviated frequency response, in English - frequency response) - amplitude dependence fluctuations (loudness) at the output from frequency reproduced harmonic signal.
The term " frequency response”Applies only for signal processing devices and sensors- i.e. for devices through which the signal passes. When talking about devices designed to generate signals (generator, musical instruments, etc.), it is more correct to use the term “frequency range”.
Let's start from afar.
Sound is a special type of mechanical vibrations of an elastic medium that can cause auditory sensations.
The basis of the processes of creation, propagation and perception of sound are mechanical vibrations of elastic bodies:
- sound creation - determined by vibrations of strings, plates, membranes, columns of air and other elements of musical instruments, as well as diaphragms of loudspeakers and other elastic bodies;
- sound propagation - depends on the mechanical vibrations of the particles of the medium (air, water, wood, metal, etc.);
- the perception of sound - begins with mechanical vibrations of the tympanic membrane in the hearing aid, and only after that a complex process of information processing takes place in various parts of the auditory system.
Therefore, in order to understand the nature of sound, one must first of all consider mechanical vibrations.
Fluctuations repetitive processes of changing any parameters of the system are called (for example, temperature drops, heartbeat, movement of the moon, etc.).
Mechanical vibrations- These are the repetitive movements of various bodies (rotation of the Earth and planets, oscillations of pendulums, tuning forks, strings, etc.).
Mechanical vibrations are primarily the movements of bodies. Mechanical movement of a body is called "a change in its position over time in relation to other bodies."
All movements are described using concepts such as displacement, speed and acceleration.
Bias is the path (distance) traversed by the body during its movement from some point of reference. Any movement of a body can be described as a change in its position in time (t) and in space (x, y, z). Graphically, this can be represented (for example, for bodies that are displaced in one direction) as a line on the x (t) plane - in a two-dimensional coordinate system. The offset is measured in meters (m).
If for each equal period of time the body is displaced by an equal segment of the path, then this is a uniform movement. Steady motion is motion at a constant speed.
Speed is the path traversed by the body per unit of time.
It is defined as "the ratio of the length of the path to the time interval for which this path is covered"
Velocity is measured in meters per second (m / s).
If the displacement of the body for equal intervals of time is not the same, then the body makes an uneven movement. Moreover, its speed changes all the time, that is, it is movement with variable speed.
Acceleration is the ratio of the change in speed to the time interval during which this change occurred.
If the body is moving at a constant speed, then the acceleration is zero. If the speed changes uniformly (uniformly accelerated motion), then the acceleration is constant: a = const. If the speed changes unevenly, then the acceleration is defined as the first derivative of the speed (or the second derivative of the displacement): a = dv I dt = drx I dt2.
Acceleration is measured in meters per second squared (m / s2).
Simple harmonic oscillations (amplitude, frequency, phase).

In order for the movement to be oscillatory (i.e., repetitive), a restoring force must act on the body, directed in the direction opposite to the displacement (it must return the body back). If the magnitude of this force is proportional to the displacement and is directed in the opposite direction, that is, F = - kx, then under the action of such a force the body makes repeated movements, returning at regular intervals to the equilibrium position. This movement of the body is called a simple harmonic vibration. This type of movement underlies the creation of complex musical sounds, since it is the strings, membranes, soundboards of musical instruments that vibrate under the influence of elastic restoring forces.
An example of simple harmonic vibrations is the vibrations of a mass (weight) on a spring.
Amplitude of vibration (A) is called the maximum displacement of the body from the equilibrium position (with steady vibrations, it is constant).
A period of fluctuations (T) is called the smallest time interval after which the oscillations are repeated. For example, if a pendulum goes through a full cycle of oscillations (in one direction and the other) in 0.01 s, then its oscillation period is equal to this value: T = 0.01 s. For a simple harmonic vibration, the period is independent of the vibration amplitude.
Oscillation frequency (f) is determined by the number of oscillations (cycles) per second. Its unit of measurement is equal to one oscillation per second and is called hertz (Hz).
The oscillation frequency is the reciprocal of the period: f = 1 / T.
w- angular (circular) frequency. The angular frequency is related to the vibration frequency by the formula ω = 2Пf, where the number П = 3.14. It is measured in radians per second (rad / s). For example, if the frequency is f = 100 Hz, then ω = 628 rad / s.
f0 is the initial phase. The initial phase determines the position of the body from which the oscillation began. It is measured in degrees.
For example, if a pendulum began to oscillate from an equilibrium position, then its initial phase is zero. If the pendulum is first deflected to the extreme right position and then pushed, it will oscillate with an initial phase of 90 °. If two pendulums (or two strings, membranes, etc.) begin their oscillations with a time delay, then a phase shift will form between them
If the time delay is equal to one quarter of the period, then the phase shift is 90 °, if the half of the period is -180 °, three quarters of the period is 270 °, and one period is 360 °.
At the moment of passing the equilibrium position, the body has maximum speed, and at these moments the kinetic energy is maximum, and the potential is equal to zero. If this sum were always constant, then any body, taken out of the equilibrium position, would vibrate forever, a "perpetual motion machine" would be obtained. However, in a real environment, part of the energy is spent on overcoming friction in air, friction in supports, etc. (for example, a pendulum in a viscous medium would oscillate for a very short period of time), therefore, the amplitude of oscillations becomes less and less and gradually the body (string, pendulum, tuning fork) stops - vibration damping occurs.
Damped oscillation can be graphically represented as oscillations with gradually decreasing amplitude.
In electroacoustics, radio engineering, and musical acoustics, a quantity called goodness systems - Q.
Quality factor(Q) is defined as the reciprocal of the damping coefficient:
that is, the lower the Q-factor, the faster the oscillations damp.
Free vibrations complex systems. Range

The oscillatory systems described above, for example a pendulum or a weight on a spring, are characterized in that they have one mass (weight) and one stiffness (springs or filaments) and move (oscillate) in one direction. Such systems are called systems with one degree of freedom.
Real vibrating bodies (strings, plates, membranes, etc.) that create sound in musical instruments are much more complex devices.
Consider the vibrations of systems with two degrees of freedom, consisting of two masses on springs.
When a string is actually excited, the first few natural frequencies are usually excited in it, the vibration amplitudes at other frequencies are very small and do not significantly affect the overall vibration mode.

A set of natural frequencies and amplitudes of vibrations that are excited in a given body when exposed to it external force(hit, pinch, bow, etc.), is called amplitude spectrum .
If a set of oscillation phases is presented at these frequencies, then such a spectrum is called phase.
An example of the vibration shape of a violin string, excited by a bow, and its spectrum are shown in the figure
The main terms that are used to describe the spectrum of an oscillating body are as follows:
the first fundamental (lowest) natural frequency is called fundamental frequency(sometimes called fundamental frequency).
All natural frequencies above the first are called overtones, for example, in the figure, the fundamental frequency is 100 Hz, the first overtone is 110 Hz, the second overtone is 180 Hz, etc. The overtones whose frequencies are in integer ratios with the fundamental frequency are called harmonics(in this case, the fundamental frequency is called first harmonic). For example, in the figure, the third overtone is the second harmonic, since its frequency is 200 Hz, that is, it refers to the fundamental frequency as 2: 1.
To be continued... .
To the question: "why so far away?" I will answer right away. That the frequency response graph is not as simple as many imagine. The main thing is to understand how it is formed and what it will tell us about.
It just so happened that the average human ear distinguishes signals in the range from 20 to 20,000 Hz (or 20 kHz). This rather solid range, in turn, is usually divided into 10 octaves (it can be divided into any other number, but it is accepted that 10).
V general case octave Is a frequency range, the boundaries of which are calculated by doubling or halving the frequency. The lower limit of the next octave is obtained by doubling the lower limit of the previous octave.
Actually, why is knowledge of octaves necessary? It is necessary in order to stop the confusion about what should be called the lower, middle or some other bass and the like. The generally accepted set of octaves unambiguously determines who is who to the nearest hertz.
The last line is not numbered. This is due to the fact that it is not included in the standard ten octaves. Pay attention to the column "Title 2". It contains the names of the octaves that are highlighted by the musicians. These "strange" people have no concept of deep bass, but they have one octave on top - from 20480 Hz. Therefore, there is such a discrepancy in numbering and names.
Now we can talk more specifically about the frequency range of acoustic systems. We should start with the unpleasant news: there is no deep bass in multimedia acoustics. The vast majority of music lovers have never heard of 20 Hz at a level of -3 dB. And now the news is pleasant and unexpected. In a real signal, there are no such frequencies either (with some exceptions, of course). An exception is, for example, recording from the IASCA Competition Judge CD. The song is called "The Viking". There, even 10 Hz is recorded with a decent amplitude. This track was recorded in a special room on a huge organ. The system, which will play "Vikings", the judges hang with awards, as christmas tree toys. And with a real signal, everything is simpler: bass drum - from 40 Hz. Huge Chinese drums - also from 40 Hz (there is one megadrum among them, though. So it starts playing from 30 Hz). Live contrabass - generally from 60 Hz. As you can see, 20 Hz is not mentioned here. Therefore, you can not be upset about the lack of such low components. They are not needed to listen to real music.
Here is another rather informative page where you can clearly (with the help of the mouse), in more detail, see this plate
Knowing the alphabet of octaves and music, you can begin to understand the frequency response.
Frequency response (amplitude-frequency characteristic) - the dependence of the amplitude of the oscillation at the output of the device on the frequency of the input harmonic signal. That is, the system is fed a signal at the input, the level of which is taken as 0 dB. The amplified speakers do what they can from this signal. It turns out that they usually have not a straight line at 0 dB, but a somewhat broken line. The most interesting thing, by the way, is that everyone (from audio amateurs to audio producers) strives for a perfectly flat frequency response, but they are afraid to "strive".
Actually, what is the use of the frequency response and why are they trying to measure this curve with enviable constancy? The fact is that it can be used to establish the real, and not whispered by the "evil marketing spirit" to the manufacturer, the boundaries of the frequency range. It is customary to indicate at what drop in the signal the cutoff frequencies are still played. If not specified, the standard -3 dB is considered to have been taken. This is where the catch lies. It is enough not to indicate at what drop the boundary values were taken, and you can absolutely honestly indicate at least 20 Hz - 20 kHz, although, in fact, these 20 Hz are achievable at a signal level that is very different from the set -3.
Also, the benefit of the frequency response is expressed in the fact that according to it, although approximately, it is possible to understand what problems the selected system will have. Moreover, the system as a whole. The frequency response suffers from all elements of the path. To understand how the system will sound according to the schedule, you need to know the elements of psychoacoustics. In short, this is the case: a person speaks within the medium frequencies. Therefore, he perceives them the best. And on the corresponding octaves, the graph should be the most even, since the distortions in this area put a lot of pressure on the ears. High narrow peaks are also undesirable. General rule here it is: peaks are heard better than troughs, and a sharp peak is heard better than a gentle one.
The abscissa scale (blue) contains frequencies in hertz (Hz)
On the ordinate scale (red) is the sensitivity level (dB)
Green - the frequency response itself
When making AFC measurements, not a sine wave is used as a test signal, but a special signal called “pink noise”.
Pink noise is a pseudo-random wideband signal in which the total power at all frequencies within any octave is equal to the total power at all frequencies within any other octave. It sounds very much like a waterfall.
Loudspeakers are directional devices, i.e. they focus the emitted sound in a specific direction. As you move away from the main axis of the loudspeaker, the sound level may decrease, and its frequency response becomes less linear.
Volume
Often the terms “loudness” and “sound pressure level” are used interchangeably, but this is incorrect, as the term “loudness” has its own specific meaning. The sound pressure level in dB is determined using sound level meters.
Equal Volume Curves and Backgrounds
Will listeners perceive test noise-like or sinusoidal signals with a linear frequency response throughout the entire audio frequency range, directed to a power amplifier with a linear frequency response, and then to a loudspeaker with a linear frequency response, equally loud at all frequencies? The fact is that the sensitivity of human hearing is non-linear, and therefore, sounds of equal loudness at different frequencies will be perceived by listeners as sounds with different sound pressure.
This phenomenon is described by the so-called “curves of equal loudness” (figure), which show what sound pressure must be created at different frequencies in order for the listeners to hear the loudness of these sounds equal to the loudness of a sound with a frequency of 1 kHz. For us to perceive sounds of higher and lower frequencies, as loud as sound with a frequency of 1 kHz, they must have a higher sound pressure. And the lower the sound level, the less sensitive our ear is to low frequencies.
The sound pressure level of the reference sound is set at a frequency of 1000 Hz (for example, 40 dB), then the subject is asked to listen to the signal at a different frequency (for example, 100 Hz), and adjust its level so that it seems equal to the reference one. Signals can be presented through telephones or through loudspeakers. If we do this for different frequencies, and postpone the obtained values of the sound pressure level, which are required for signals of different frequencies, so that they are equal in volume with the reference signal, we will get one of the curves in the figure.
For example, for a 100 Hz sound to sound as loud as a 1000 Hz sound at 40 dB, its level must be higher, around 50 dB. If a sound with a frequency of 50 Hz is heard, then in order to make it equal in volume with the reference one, you need to raise its level to 65 dB, etc. If we now increase the level of the reference sound to 60 dB and repeat all the experiments, we get a curve of equal loudness corresponding to a level of 60 dB ...
A family of such curves for different levels of 0, 10, 20 ... 110 dB is shown in the figure. These curves are called curves of equal loudness... They were obtained by scientists Fletcher and Manson as a result of processing data from a large number of experiments conducted by them among several hundred visitors to the 1931 World's Fair in New York.
At present, the international standard ISO 226 (1987) adopted the refined measurement data obtained in 1956. It is the data from the ISO standard that are presented in the figure, while the measurements were carried out in free field conditions, that is, in a damped chamber, the sound source was located in the front and the sound was fed through the loudspeakers. New results have now been accumulated, and it is expected to refine these data in the near future. Each of the presented curves is called an isophone and characterizes the volume level of sounds of different frequencies.
If you analyze these curves, you can see that at low sound pressure levels, the estimate of the loudness level is very dependent on frequency - hearing is less sensitive to low and high frequencies, and much higher sound pressure levels need to be created in order for the sound to sound equally loud with the reference sound 1000 Hz. At high levels, the isophones are leveled, the rise at low frequencies becomes less steep - there is a faster increase in the volume of low frequency sounds than medium and high ones. Thus, at higher levels, low, medium and high sounds are judged more evenly in terms of loudness.
So. We have the sound pressure level and loudness measured with the help of measuring equipment, which is physically perceived by a person.

This raises a question! By removing the frequency response of the speaker with the help of measuring equipment, what do we get? What does OUR ear hear? Or what readings does the microphone take with its sensitive element of the measuring equipment? And what conclusion can be drawn from these readings?
This raises a question! By removing the frequency response of the speaker with the help of measuring equipment, what do we get? What does OUR ear hear? Or what readings does the microphone take with its sensitive element of the measuring equipment? And what conclusion can be drawn from these readings?

Determination of mass using weighing instruments is the most accurate, but rather laborious operation, which causes significant downtime of the rolling stock. Therefore, in practice, calculation methods for determining the mass of the cargo are more often used. The mass of cargo at the point of destination is determined in the same way as it is established at the point of departure.

In river ports, for weighing goods, beam scales are mainly used, operating on the principle of balance of levers, from which cargo is placed on one, and weights on the other. Such mechanisms include mobile and stationary commodity scales, automobile, wagon and bucket elevator scales.

The balance conditions of the beam balance are expressed by the formula

Pl = P 1 l 1

where P, P 1 - forces applied at the ends of the arm (weights and weighed weight);

l, l 1 - the length of the lever arms from the fulcrum to the point of application of the forces.

Lever scales of various types work on the basis of this principle. Weighing (comparison of the mass of the weighed body with the mass of weights) is carried out taking into account the length of the arms of the levers.

For weighing goods in the process of moving them by crane or conveyor, conveyor and crane electromechanical scales are used. The amount of cargo on the weighing platform, depending on their design, is established by calculating the conditionally nominal mass of the balancing weights or according to the indications on the scale, dial, discrete-digital device.

The scheme of operation of the beam scales

Scales with scale indications do not require overhead weights. Their balance is achieved by moving the movable weight on the scale (which changes the lever arm), the weighing result is visible directly on the scale. On dial scales, the weight of the load is determined by the angle of deflection of the rocker arm from the initial equilibrium position. On discrete-digital scales, the weighing result is recorded on a special display using an electronic device.

The main properties of any balance are sensitivity, stability; fidelity and consistency of weight readings.

Sensitivity balance is the ratio of the mass of the additional weight, which caused the deflection of the rocker arm by 2-5 mm from the equilibrium position, to the mass of the main weight on the scale platform. The smaller is this ratio; the more sensitive the balance and the more accurate the weighing result. The sensitivity of the balance depends on the length of the rocker arm, the distance between the center of gravity of the balance and the suspension point of the rocker arm, and on the frictional forces at the suspension point of the rocker arm.

Sustainability the property of the scales is called to return to the original equilibrium position after several smooth oscillations of the rocker arm, taken out of the equilibrium state.

Loyalty, that is, the accuracy of the balance reading depends on the correct ratio of the lever arms and the friction force that occurs in the supporting parts of the mechanism. Due to the impossibility of eliminating the effect of friction and achieving an absolutely accurate ratio of levers for all scales, GOSTs have established permissible errors.

Constancy is called the invariability of the readings of the scales during repeated weighing of the same cargo. Consistency largely depends on compliance with the rules for maintaining the scales.

Weighing scales have a stable location of the load-receiving platform. They are manufactured with a carrying capacity of 1000, 2000, 3000 kg. Stationary commodity scales are deepened into the floor of the warehouse so that the load-receiving platform is at the floor level. The correctness of the installation of commercial scales is checked by the level or plumb line located on the column of the scales.

Car weights have the largest weighing limits of 10-150 tons. They are installed on a solid foundation not in a warehouse, but on the territory of the port on the way of traffic. Scales are designed for weighing goods together with cars and road trains.

The mass of the load is defined as the difference between the mass of the laden and unladen vehicle.

Wagon scales can be single or double. The maximum weighing limit is 60, 150 and 200 tons. Two-platform scales are designed for weighing wagons of different lengths both on one and on two platforms. Two platforms of different lengths (15.5 and 3.7 m) are installed on a common foundation. All sub-platform linkages are attached to one common rocker arm. Connection to the rocker arm of each platform separately or two together is carried out using a special device.

When weighing goods on a wagon scale, it is necessary to observe following rules: weigh each carriage separately; to feed the wagons to the scales (with a fixed weight beam) at a speed of no more than 5 km; uncouple the wagons so that they are in a free state (it is not allowed to weigh wagons without uncoupling, except in cases stipulated by the rules); when determining the mass of valuable cargo, check the tare weight of the wagons;

when determining the mass of bulk cargo, the container of the car is taken according to the stencil inscription on the channel bar of the car.

Railway strain gauge scales VZHTD-ELKOM-150.

Scales are designed for axle weighing of moving wagons in a train. Weighing is carried out without uncoupling the train with registration of the mass of each car and the mass of the train as a whole.

Automatic bucket scales used for weighing bulk cargo, in particular grain in elevators. Scales are made of two types: with a tipping bucket and with an opening bucket bottom. On automatic scales with an opening bucket bottom, the grain is weighed as follows: a weight holder suspended from the end of the rocker arm is lowered under the action of the weight of the weights, and the bucket, fixed at the opposite end of the rocker arm, rises up and opens the hopper gate. Grain from the hopper enters the bucket, which is lowered under its weight. When the balance of the rocker arm is reached, the hopper gate closes, and the bucket, continuing to descend by inertia, reaches the stop. At the same time, its bottom, held by a latch, opens and the grain is poured into the receiver. The bucket, freed from the load, rises again, its hinged bottom closes, the hopper gate opens, and the weighing cycle is repeated.

Calculation method

5.3.1 Based on the standard weight of the package.

When transporting packaged goods in standard containers (sugar, flour, cereals in bags, confectionery and pasta in boxes, fabric, knitwear in bales and bales, cement and fertilizers in paper and plastic bags, drinks in barrels, etc.) cargo is determined by standard mass of one package and the total number of seats.

where: G gr - weight of the consignment, T;

q gr- weight of one standard piece of cargo , T;

n gr - number of pieces in a consignment , units

5.3.2 According to the conditional weight of the place.

By stencil the mass indicated on the cargo places is transported: butter, margarine, cheeses, canned food and drinks in glass containers, fish products, food concentrates, footwear, clothing, metal products, devices, equipment, machines, etc.

By conditional Bulky piece cargo is transported in bulk in containers and without packaging (cars, agricultural machines, earth-moving equipment, shells, reactors, pipes of large diameters, etc.). The conventional weight of individual piece cargo is given in the Tariff Guide 1-P, Price List 14-01 Tariffs for the carriage of goods and towing of rafts by river transport (Appendix 5 Conventional weight of individual piece cargo).

5.3.3 By the volume of the consignment.

When determining the mass of bulk and bulk cargo, timber and firewood by measuring, the cargo is stacked at the coastal warehouse in stacks of the correct and convenient shape for measurement. The volume of cargo established by measurement in cubic meters is multiplied by the mass I m 3 of this cargo, indicated in the Tariff Guide No. 1-P (Appendix 6. Conversion of volumetric measures into weight measures). The product expresses the mass of the cargo in tons. The volume of the cargo is determined depending on the geometric shape that it forms during storage, using the well-known geometry formulas (see table).

Timber is taken into account volumetric measurement in cubic meters, and export timber - standards. To determine the mass of timber, conversion factors from volume to mass are used, depending on the forest species, its moisture content (freshly cut and air-dry round timber).

The mass of round timber is also determined by the marking of each log, at the ends of which the diameter is affixed.

For instance:

Table 16

Formulas for calculating the volume of the main forms of cargo

5.3.4 By the draft of the vessel.

This method of determining the mass is based on the principle of calculating the displacement of a vessel when its draft changes as a result of loading or unloading. The method is used in cases where the cargo is not weighed on the scales, or its mass is conditionally determined by the sender (by measurement), or a control check of the mass is necessary to calculate the freight charge.

To determine the displacement, you need to know its main dimensions in meters: estimated length L p hull waterline, design width In p midship frame at waterline level, maximum draft T g for a given navigation area, empty draft That, ratio b displacement completeness, coefficient of water density. Displacement D s is determined as the product of these values:

For fresh water = 1. The density of seawater varies with temperature and salinity.

The ship's cargo scale is designed for an average water density of 1.026.

Displacement of the vessel, laden ( D g) and unload (D o) states are determined by similar formulas, taking into account the corresponding sediment and displacement completeness coefficients.

where T n , T With, T to- draft, respectively, of the bow, middle and stern parts of the ship on the starboard side, m;

T "n, T" s, T "k- the same, on the port side, m.

Similarly, the draft of the vessel after loading is determined and calculated.

The cargo scale of the vessel (table of cargo size) is given

in table. 5.1

Table 5.1

Cargo scale for motor ship

project No. Р25 А class "0", Q = 1500 t

Note: For the initial displacement of the vessel D = 560 t, the vessel's displacement is taken as a light vessel with full stores without ballast.

5.3.5 Determination of the mass of oil cargo

Oil and oil products are transported by river transport in specialized self-propelled and non-self-propelled rolling stock. Loading and unloading of oil products in bulk is carried out at specialized berths of oil depots, equipped with special pumps for pumping.

Determination of the mass of petroleum products is carried out in two ways:

the first one is based on measurements of onshore reservoirs of oil storage facilities with calibration tables, or according to special meters of oil storage depots;

the second - by measuring the height of loading or unloading in the cargo compartment of a river vessel.

Onshore tanks should have standard calibration tables, in the absence of which meters are installed, which should ensure the loading capacity of vessels not lower than the established standards. Technically sound tools must be used at the berths of petroleum products.

On the ship, to determine the height, a tape measure with a lot or a measuring rod with a water-sensitive tape attached to them is used. The ship should have calibration tables by which the volume of loading or unloading is determined. The procedure for performing the operation according to the Rules for the carriage of goods and the corresponding GOSTs.

It might be helpful to read: