No. 6 (2019)

Modeling a MEMS gyroscope accelerometer with the use of SIMULINK. For modeling,
a 2-axis accelerometer is used, developed as part of patent No. 2683810. When linear acceleration
occurs along an axis located in the plane of the semiconductor substrate, the inertial masses under
the action of inertia begin to move along the X axis in the plane of the semiconductor substrate,
due to the bending of elastic beams, which are rigidly connected at one end to the moving electrodes
of capacitive displacement transducers and the other with supports, respectively, of elastic
beams and "P"-shaped systems of elastic beams that are rigidly connected at one end to the movable
electrodes of the capacitive transducer of movements, and others - with supports. The voltage
difference generated by the capacitive displacement transducers formed by the fixed electrodes of
the capacitive displacement transducers and the movable electrodes of the capacitive displacement
transducers, respectively, due to a change in the gap between them, characterizes the magnitude of
the linear acceleration. When electrostatic drives with comb structures of alternating voltages,
1800 phase-shifted relative to each other, are applied to the stationary electrodes relative to the
movable electrodes, an electrostatic interaction occurs between them, which leads to the appearance
of out-of-phase oscillations of the moving electrodes in the plane of the semiconductor substrate
along the X axis due to bending elastic beams. Oscillations are transmitted by the stiffening
plates of the elastic suspension 86, 87, which causes out-of-phase oscillations of inertial masses in
the plane of the semiconductor substrate along the Y axis. The voltage difference generated by the
capacitive displacement transducers formed by the stationary electrodes of the capacitive displacement
transducers and the moving electrodes of the capacitive displacement transducers,
respectively, due to changes in the gap between them, characterizes the amount of displacement of
inertial masses under the influence of electrostatic human forces. Thus, in comparison with similar
devices, the proposed integrated micromechanical gyroscope-accelerometer reduces the substrate
area used for the placement of measuring elements of the angular velocity and linear acceleration,
since for measuring linear acceleration along the X and Y axes located mutually perpendicular to
the plane the substrate, and the Z axis directed perpendicular to the plane of the substrate, and the
angular velocity along the X axis located in the plane of the substrate, and the Z axis directed per
Pendicular to the plane of the substrate, only one integrated micromechanical sensor is used. For
mathematical modeling of such systems, it is customary to use HAMSTER, but in our work we
preferred SIMULINK to it. Simulink is a graphical simulation environment that allows using block
diagrams in the form of directed graphs to build dynamic models, including discrete, continuous
and hybrid, nonlinear and discontinuous systems. Simulink interactive environment allows you to
use ready-made library libraries for modeling electric power, mechanical and hydraulic systems,
as well as apply the developed model-oriented approach to the development of control systems,
digital communications and real-time devices. A relevant topic for research is the development of
the design of a MEMS accelerometer of high accuracy and noise immunity. Previously, mathematical
modeling of the movement of the micromechanical accelerometer was performed, but the output
result needed to be adjusted. This article demonstrates the adjustment of the mathematical
model by introducing the transfer function into it.

Wireless microdevices are widely adopted in Radio-Frequency Identification (RFID), Wireless
Sensor Networks (WSN), Internet of Things (IoT). Among them, passive devices have a special
place, since they haven’t constant power supply (battery energy storage). Passive devices (passive
RFID tags, sensors with possibility to receive and transmit the data) are cheaper and more compact
than their active analogs, their lifetime is higher, and they can be applied in some applications,
in which using of active tags is not always possible, e.g. in medical implants. However passive
devices have to receive the energy for operation from the outside through RF radiation – from
base station (reader) or harvesting energy from the environment. For conversion this energy to
power supply voltage of passive microdevice IC, voltage rectifiers and multipliers are used. The
purpose of this work is research of impact on output voltage by parameters of nanoscale diodeconnected
MOSFETs, which perform functions of rectifiers in the energy converters. The comparison
of different voltage rectifier configurations, based on nanoscale diode-connected MOSFETs,
was made based on Tanner EDA software simulation results. The current-voltage characteristics
of diode-connected MOSFETs were obtained for 90 nm, 65 nm and 45 nm CMOS technologies.
The impact of transistor threshold voltage and its sizes (relation of transistor width to length) on
output voltage of single-stage multiplier for different technologies, input voltage amplitudes and
load resistances was investigated. It was shown that at certain values of threshold voltage maximums
of the output voltage are observed. The optimal value of threshold voltage is shifted to low
values region with load current rising. The obtained results show the possibility of the multipliers
operation in transistor subthreshold region, which allows to ensure the possibility of operation at
low input voltages and fulfills the condition of wireless passive microdevices functioning at significant
distance from base station or in case of obtaining energy for supplying from the environment.
The results of the research can be useful in the design of wireless passive microdevices.

We consider the problem of increasing the volume of hard magnetic disks (HDD) memory. The
key place in the series of external computer storage devices is occupied by hard disk, because the
volume of information storage in them is constantly growing. We analyze the methods of information
recording for HDD. Thin magnetic film is the storage medium in hard disks. Thin-film technology is
mainly used for thin films formation. We consider the main principles of choosing the ferromagnetic
film composition based on the technical requirements for a hard magnetic disk, its geometric and
functional features. The comparative characteristics of various methods for thin films producing are
given. Nowadays the method of magnetron sputtering is intensively developed, providing controlled
sputtering of thin layers with the required parameters. When the target of the magnetron sputtering
device is used repeatedly, an erosion zone is formed in it, which directly affects the sputtering rate of
the material (film thickness). The thin film thickness decrease leads to a deterioration in the electrical
resistivity, i.e. to the irreproducibility of the required characteristics and parameters. We consider
the advantages of the magnetron sputtering method. The choice of coating materials that ensure the
performance of hard magnetic disks is the main factor for the technological design of magnetron
sputtering processes. We analyze the possibility of using Co-Cr pheromagnetic films for hard magnetic disks. The dependences of the influence of the substrate material on the magnetic properties of
ferromagnetic films, the effect of the deposition rate of Co films by magnetron sputtering on the coercive
force of ferromagnetic films, and the effect of the temperature of the substrate on the properties
of Co-Cr films are defined. We present the main parameters of the coating process by magnetron
sputtering for various ferromagnetic materials. The samples based on Co-Cr thin magnetic films
meet modern requirements in terms of increasing the recording density of hard magnetic disks. The
large coercive forces and values of relative remanent magnetization can be achieved in them.

The aim of this work is to develop manufacturing technology, the formation and study of
GaAs/Si heterostructures created by a two-stage method, as well as comparison with GaAs/Si
heterostructures obtained by a one-stage method. In this work, we study the two-stage growth
regimes of GaAs/Si heterostructures obtained by molecular beam epitaxy (MBE), which can be
used as the basis for creating elements of optoelectronics. The morphology of the surface of
GaAs/Si heterostructures and structures created using embedded layers (buffer layers) were studied.
According to the results of the morphology of the surface of the GaAs layer, it was revealed
that the surface of the sample created by the single-stage technology was formed by single-crystal
GaAs cells with sizes 1.5x2 μm. At the same time, the surface of the sample formed by the twostage technique has smaller GaAs single crystals with sizes of 250x250 nm. In the first and second
cases, the films consist of separate single-crystal blocks, which in the process of growth merged with
each other, forming a continuous film, with a certain surface roughness coefficient, which is visible
from SEM images. Technological conditions for the deposition of GaAs films by the MBE method on
Si, as well as the SiO2 layer on Si obtained by plasma-chemical deposition in an inductively coupled
plasma, have been developed. Windows were formed in the SiO2 layer by photolithography and
chemical etching with a diameter of 4 μm. The methods of two-stage and one-stage growth of GaAs
on Si are compared. The distribution of the surface potential was studied, and a band energy model
was constructed. The current-voltage characteristics of the obtained GaAs/Si heterostructures under
the influence of radiation and in the dark were constructed and studied. During the study of the samples,
it was found that heterostructures grown by the two-stage growth technique have a photosensitivity,
which is especially pronounced with ultraviolet radiation, at a wavelength of light radiation of
about 400 nm. The results of the study suggest the promise of using GaAs/Si heterostructures created
by the two-stage growth technique as the basis for creating optoelectronic devices.

Microelectromechanical systems (MEMS) are based on the use of micromechanical components
implemented using microelectronic technologies. MEMS gyroscopes and accelerometers are
widespread, and they are implemented as a stackable design because of the joint implementation
complexity of mechanical sensor and data processing system, which converts sensor’s output signals
to digital or analog signal, in one technological process. One of the causes of this configuration
outspread is the use of analog circuitry elements in data processing devices, the implementation
of which in integrated form does not contribute to solving the problem. Furthermore using of
two process flows in sensors manufacturing increases sensors self-cost substantially. This paper
presents the research results of the digital capacitance-to-frequency converter, technology of
which is compatible with the surface micromachining technology of the integrated micromechanical
sensors. The output data of this converter is the frequency of the digital signal that needs to be
measured and converted to binary code. To solve this problem, a low-power digital frequency
meter was researched, and the implementation of a digital converter and frequency counter as a
device for the primary processing of data from gyroscopes-accelerometers was also considered.
The dependence of the frequency value of the converter’s output signal F on the capacitance C_x
was obtained; frequency variation was 0-13.5 MHz while capacitance was changed from 0 to
50 fF. The dependences of the range of the measured frequency of the frequency meter on thecounter capacity 1-10 and the clock generator frequencies 0.25, 0.5  1 GHz were obtained, as well as dependencies of the frequency meter power consumption 18-60 μW on the clock generator
frequencies 0.25-1 GHz.

Micromechanical acoustic transducers based on membranes have been used in medical diagnostic
systems, range finders, hydroacoustics, as well as in biometric security systems. The
range of tasks solved by such devices is constantly expanding, the requirements for increasing the
measuring range, accuracy, reducing the size and energy consumption are increasing. In addition,
many acoustic applications require sensor arrays integrated with electronic signal processing
systems. These features have determined the need for the use of micro-processing methods for
their industrial production. The aim of this work is to design and form silicon membranes for
acoustic sensors with operating ranges of resonant frequencies from 10 kHz to 100 MHz and pressures
from 0.1 to 1000 kPa. In this paper, the design of single-crystal silicon membranes for preparation
by anisotropic liquid etching is evaluated. Analytical dependences of pressure and resonance
frequency on geometrical parameters of membranes are presented. We defined the ranges
of the thickness (10–50 microns) and the length of the fin membranes (200-600 microns). The topology
of the photomask for the manufacture of such membranes is calculated. Experimental studies
of the etching of the si plate with a solution of 30% KOH were carried out and the etching rate
was found to be 1.25±0.1 μm/min. Anisotropic liquid etching was used to form silicon membranes
of quadrate shape with thickness of 50 μm with fin lengths from 200 to 250 μm with resonant frequencies
in the range from 1.9 to 3 MHz. The results obtained could be used in the development of
acoustic sensors made of monocrystalline silicon.

The work is devoted to the development of technology of manufacturing a multielectrode microprobe
(neuroprobe) using surface micromachining and anisotropic wet etching of silicon based
on the infrastructure of the Research and Education Centre "Nanotechnologies" of Southern Federal
University. The development was carried out to implement a typical design of the neuroprobe, which
consists of a base, several beams of rectangular shape with a pointed end and electrical interface.
The process flow based on 4 photolithography steps and includes 18 main operations like substrate
cleaning, thermal oxidation, plasma-chemical deposition of silicon oxide an nitride d, rapid thermal
annealing, plasma-chemical etching of silicon nitride and oxide, isotropic and anisotropic wet etching
of silicon oxide and monocrystalline silicon, and metals deposition by electron-beam evaporation.
Experimental researches of anisotropic wet etching of monocrystalline silicon in a potassium
hydroxide solution through a mask of plasma deposited silicon oxide, as well as the effect of rapid
thermal annealing on the mask resistance were conducted. The effect of the solution concentration
(from 10 to 40%) on the etching rate and surface roughness at 80 °C was studiedThe etching in 27–
30 % KOH solution leads to formation of a surface with a minimum average roughness value of 13
nm. The etching rates of monocrystalline silicon and silicon oxide were 1.5 μm/min for (100) face,
3 nm/min for (111) face, and 10 nm/min, respectively. Rapid thermal annealing at 600 °C for 3 min
increases resistance of silicon oxide the alkaline solution by 2 times. The developed technology was
tested on the example of formation a two beam neuroprobes on 420 thick 4’’ silicon wafer (100). A
series neuroprobe structures was fabricated. The developed technology could be used for the fabrication
of neuroprobes with various numbers and placement of beams and electrodes.

Based on the analysis of the main dispersion-dependent mechanisms describing the behavior
of the effective mass under the action of strong electric fields (EF) in the volume of AIIIBV –
type semiconductors, a generalized relation is obtained for the dependence of this charge carriers
effective mass on energy. Further application of this relation in the phenomenological theory for
the drift-diffusion model including the heating and drift equations, as well as when the action of a
strong magnetic field is orthogonal with respect to the drift direction, made it possible to represent
all the relations in component form for the longitudinal and transverse coordinates. This idea
made it possible to identify a number of new effects, among which the most significant are the following:
from the obtained frequency response and phase response of the output conductivity of a particular
volumetric structure, it was found that it is possible to select the required constant field strength
value that provides the required mode of operation of devices on such structures in a given frequency
range; with increasing magnetic field (MF) induction, an increase in the velocity value occurs along
the drift direction, and then falling sections appear on the drift induction characteristic in the transverse
direction, which indicates the possibility of using this effect to create nonlinear induction active
elements; the amplitude dependences of constant and variable diffusion coefficients were found,
which can be defined as the “volume diffusion detector effect”. It was also revealed for the first time
that the components of the drift velocity and the diffusion coefficient along the longitudinal axis of the
drift direction do not depend on the transverse MF, but are determined only by the longitudinal EF
along this direction, and the transverse component of the drift velocity at strong values of the MF
induction B>4 T, shows a shift the beginning of the falling section on the drift (current-voltage)
characteristic decreases (by 2 times), which indicates the discovered new "Gunn effect controlled by
the magnetic field." In this case, a decrease in the value of the threshold field strength of the Gunn
effect from 4 to 2 KV / cm will increase the efficiency of the volume diode by 50 %. The fundamental
possibility of creating two-dimensional devices for frequency conversion (autodyne type mixers)
and magnetically sensitive detectors has been revealed.

The paper presents the results of work on the development of resistive structures of sensor
elements based on silicon-carbon films, which according to the literature data have high stability.
Silicon-carbon films were prepared by electrochemical deposition from a solution of
hexamethyldisilazane with methanol in a ratio of 1:9. Two types of structures were used as substrates
for the manufacture of resistive sensor structures: a dielectric substrate with a high resistance
chromium sublayer and a dielectric substrate with a copper sublayer in the form of a
group of thin slits. Silicon-carbon films were deposited on the surface at a current density of 50
mA / cm2. In this case, the deposition time on the substrate of polycor with a high resistance
chromium sublayer was 30 minutes, and on the dielectric substrate with a copper sublayer in the
form of a group of thin slits-4 hours. The structure of the obtained samples was studied using the
method of Raman spectroscopy. It is shown that silicon-carbon films have a complex structure
including various phases of silicon carbide, graphite and diamond. Gas sensing properties of sensor
elements was evaluated against carbon monoxide and methane with concentrations of 16 and
297 ppm, respectively at operating temperature of 200°C. was studied electrophysical characteristics
of RC structures by voltammetry as well as by Mott –Schottky, allowing to estimate the conductivity
type of silicon-carbon films composed of designed RC structures. It was determined that
the resistive structures of both types demonstrate p-type conductivity at room temperature, and the
resistive structure on a dielectric substrate with a copper sublayer changes the type of conductivity
when heated to 200 ℃ from p to n.

It is known that nanostructured materials based on oxide semiconductors have great potential for
practical application. In particular, zinc oxide (ZnO) nanostructures are used to manufacture sensitive
elements of gas sensors, photo and piezoelectric transducers, and energy harvesters. Oxide semiconductors
have a significant temperature dependence of resistance. In this regard, an experimental and theoretical assessment was made of the effect of the gas flow rate on the resistance of a sensor element based
on an array of ZnO nanorods. It was shown that a sensitive element based on an array of ZnO nanorods
can be used to measure low gas flow rates. Arrays of ZnO nanorods were grown on a glass substrate
using chemical technologies and had a predominantly vertical orientation with a height of 590–660 nm
and an average transverse size of about 30–40 nm. Contact metallization of V-Cu-Ni with a thickness of
0.2–0.3 μm was deposited on top of the nanorods. Subsequently, the dependences of the resistance of the
formed sensitive element on temperature and on the air flow rate were measured. It was shown that
when an air stream is supplied with a speed from 0 to 12.5 cm3/s to a sensitive element heated to 200 °С,
its resistance increases linearly up to 20 %. Calculations based on the temperature dependence of the
resistance showed that such an increase in the resistance of the sensitive element corresponds to a decrease
in the temperature of ZnO nanorods by 4 degrees. Theoretical estimates showed that the reason
for the increase in resistance is a decrease in the temperature of the free ends of ZnO nanorods by several
degrees when they are blown by an air stream

The study of the characteristics of a silicon micromechanical gyroscope (MMG) under
the influence of ambient temperature is necessary to solve the problem of ensuring the stabi lity
of its characteristics. MMG tests have shown that resonant frequencies increase with i ncreasing
temperature. The main reason for this is the occurrence of stresses in elastic su spensions
due to a mismatch between the thermal linear expansion coefficients (TLEC) of the
silicon structure and the glass substrate. The silicon sensitive element of the gyroscope was
designed so that the natural frequencies of the primary and secondary oscillations were
12.5kHz and the frequency mismatch between them was no more than 10Hz. The studied sample of the sensitive element was packed in the case under a pressure of 10-2Pa. The test results showed that the natural frequency of the primary oscillations at 20°C takes the value of 12,585kHz, and the natural frequency of the secondary oscillations is 12,609kHz. The temperature coefficients of variation of the natural frequency of the primary and secondary oscillations
in accordance are 1,61Hz/°C and 1,31Hz/°C.

The article presents a new algorithm for modeling the transmission and non-linear composition
of signals without using the principle of superposition in a fragment of a cross-bar system
based on Kirchhoff's laws. The algorithm is necessary to improve the structure and existing design
technology of non-volatile memory using a circuit solutions as part of the concepts of technical
nanoelectronics. In this model, it is proposed to apply the theory of the electronic wave circuit to
adjust the parameters of two-electrode devices and metal wires, aimed at minimizing the power
consumption and heat dissipation, increasing the clock frequency and efficiency of digital integrated
circuits without drastically changing the existing production technology. The methods of
equivalent sinusoids and circuits, complex amplitudes and harmonic linearization are used for the
analytical solution of the electric state equations and the analysis of the amplitude-dependent
summation of signal effects in system due to the multifactor dependence of the cross-bar system
parameters. The obtained analytical relations in the monochromatic approximation allow to estimate
the inertial and nonlinear properties of the cross-bar system, specified by all of its elements
that are functioning correlated in the general electromagnetic field. It is shown that the voltage
waves at the terminals of a separate memristor will be "distorted" by the connecting lines and will
not correspond to the initial signal due to the transformation of the stored signal and the phenomenon
of controlled interference in the fragments of resistive memory.

The use of composite materials in modern aviation requires, at the early stages of designing,
close collaboration between designers, tough engineers and technologists. This is primarily due to the
anisotropic (in the general case) properties of composite materials. Weight optimization of PCM assemblies
and parts is a complex multi-parameter task, including: – selection of material with desired properties;
– the formation of a sandwich package with the orientation of the monolayers, in accordance
with the fields of the tensors of the main flows; – providing static strength and stability loss analysis;
– selection and development of a technological process, etc., etc. In the present work, the analysis of the
SSS of one of the units of the aircraft at the stage of modifying the existing structure in accordance with
the decision on the replacement of metallic materials with polymer composite materials is carried outThe calculation of SSS was carried out in the MSC software system. Software at the stage of issuing
working design documentation. Positive excesses of strength are obtained using fracture criteria for
PCM by linearly static analysis, analysis taking into account geometric nonlinearity and analysis for
buckling. SSS is received for flight cases of loading and parking cases of loading (action of wind load).
Based on the analysis, it was decided to develop a test program of samples to confirm the physical properties
of materials and packages composite materials. Also in the future, life tests will be carried out to
confirm the design life. Subsequently, the work will be accompanied by an analysis of SSS on the FEM
at the stages of sample testing, static and life tests.

The study of the main processes taking place in the atmosphere is of considerable interest to
science. Monitoring of physical processes in most cases is carried out using an instrumental method
based on the introduction of a measuring probe into the test medium, which is widely used hot-wire
transducers. The aim of this work is to identify and analyze the sources of errors of measurement the
results obtained using a constant temperature hot-wire anemometer in turbulent gas flows and develop
recommendations for minimizing them. The article discusses the sources of errors that arise when
measuring a constant temperature in a turbulent gas flow with an anemometer, as well as suggestions
for minimizing them. The considered sources of errors are conventionally divided into two
types. Errors of the first type are due to the use of incorrect algorithms for processing the output
signal of the hot-wire anemometer, and of the second type due to the features of the sensor in the
feedback system. It is determined that in order to eliminate the error of the first type, it is necessary to
exclude integrating circuits in the hot-wire anemometer circuit, which weaken the amplitude of turbulent
pulsations. An error of the second type arises due to the asymmetric reaction of the hot-wire
anemometer to increase and decrease the flow rate, i.e. for heating and cooling the sensing element
(sensor). The second type of error depends on the flow rate, turbulence intensity, and velocity pulsation
spectrum. As well as the error of the first type, the compensation of this error requires special
technical solutions in the development of the electronic circuit of the hot-wire. To solve this problem,
the dynamic characteristics of the hot-wire under dynamic conditions were investigated using an
aerodynamic bench creating a stratified airflow simulating a step test signal by rapidly moving a
constant temperature sensor the hot-wire between two streams. The results can be used to develop
devices and programs for measurements in turbulent flows.

In this work the research of heat-removing properties of extended surfaces areas, for example,
finned and needle radiators, for assessment of efficiency of thermal field and heat extraction
distribution is described. Also the description of the carried-out computational modeling is provided
in the Fluent processor of the final and element analysis universal program system Ansys.
The relevance of the selected subject is confirmed by the fact that one of the most important and
difficult tasks arising when developing the electronic equipment is a withdrawal of heat generated
by it. At a current steady trend in reduction of dimensions of electronic devices this problem does
not disappear, and on the contrary, becomes more and more sharp, and that is stronger, than device
high power less its physical volume, and not only the efficiency of heat extraction, but also
dimensions and, of course, reliability of electronic devices operation depends on constructions of
heat-removing elements. Applicable, for example, to the electronic equipment, a source of thermal
power is heatterminated element. In that case when heat conductivity of the environment is applied
to normalization of its thermal mode heat sinks (radiators) insufficiently – heat-removing constructions
from metal with big coefficient of heat conductivity (copper, aluminum) as the heat conductivity
coefficient in metals is higher. In work the conclusion is drawn that for a solution of a
complex problem of efficiency assessment in the heat sink for the purpose of decrease in temperature
of heatterminated element, it is necessary to use an electrothermal analogy.

The aim of the work is to experimentally study the role of self-action effects accompanying
the propagation of ultrasonic beams of the biharmonic pump wave on the formation of spatial
characteristics of difference frequency wave field. The article studies the changes in spatial distributions
of the wave amplitude of the difference frequency under the combined action of quadraticnonlinear
effects (amplitude-dependent nonlinear attenuation), acoustic flow and heating of the
medium by finite amplitude pump waves. The experiments were carried out in a 211 m3 laboratory
pool with fresh water at room temperature, where a flat piezoceramic radiator with a diameter
of 20 mm horizontally emitted a pump wave beam with an average frequency of 2 MHz. The
biharmonic pump wave generated a difference wave in the water with a frequency of 80 kHz or
160 kHz. A small hydrophone was moved horizontally along and across the acoustic axis of the
pump beam to record axial and transverse distributions of the difference frequency wave amplitude. The amplitude of the pump waves, duration, repetition period and duty cycle of the emitted
pulses were used as the parameters of the study. At constant amplitude of the emitted waves, the
pulse duty cycle determines the average pump intensity, on which the development of self-action
effects depends. In contrast, the quadratic-nonlinear effects are determined by the amplitude of the
pump wave and do not depend on the duty cycle. Increasing the amplitude of the pump waves and
the constant duty cycle shows a joint increasing effect of quadratic-nonlinear effects and selfaction
effects on the spatial characteristics of the difference frequency wave field. For water at
room temperature, the acoustic flow and thermal self-action led to the pump beam defocusing,
which significantly accelerated the spatial loss of the difference frequency wave amplitude with the
distance from the emitter along the acoustic axis. It is shown that the greatest influence of selfaction
effects takes place in the continuous mode of radiation. The obtained results are of interest
for understanding the features and degree of influence of self-action effects on the field of difference
frequency waves, which is important when using a nonlinear acoustic emitter in measuring
and diagnostic tasks, for information transmission and remote search of objects.

Recurrence of cancer, arising from the remaining after surgery metastases and small tumors,
forcing surgeons to increase the volume of resection in surgical interventions. The paper
presents a procedure for selecting the optimal characteristics of the scintillation material for the
registration of gamma radiation from a radiopharmaceutical drug. Using interpolated data, the
dependence of the probability of interaction of a gamma quantum with a substance on the thickness of the scintillator for a radiopharmaceutical drug based on technetium 99mts radionuclide,
which most intensively emits gamma quanta with an energy of 140.5 keV, is estimated. The values
of the optimal length of sodium iodide scintillator doped with thallium NaI(Tl) for registration of
radiation from technetium-99 isomer were numerically estimated. It is established that in the process
of optimizing the size of the scintillator it is necessary to come to such a compromise that the
maximum absorption of γ quanta is provided and at the same time the optical losses in the volume
are minimal. The possibility of manufacturing detectors with a theoretically maximum sensitivity
limit in the form of a compact, suitable for manual use diagnostic device is shown. For scintillation
products, the factors influencing the light output index are given. It is established that it is
necessary to take into account not only the conversion efficiency and linear attenuation coefficient
for a given radiation energy, but also the transparency of the scintillation material to its own radiation,
which is directly affected by the chemical purity of materials and manufacturing technology
of crystal scintillators.

The use of sonar to study life in the oceans is an important tool for research in marine biology.
The сentral goal of biological oceanography is to understand the mechanisms of regulation of
plankton populations. Zooplankton is a key component of food webs. Biological sampling methods
were commonly used to measure zooplankton concentrations. These methods are based on sampling
zooplankton in nets. Underwater acoustic technologies are one of the most effective tools for
detecting and mapping aquatic organisms such as zooplankton. Quantitative measurement of marine
zooplankton using sonar equipment requires a detailed knowledge of their scattering properties.
In this paper it is proposed to improve the known method of remote identification of small fish
and zooplankton, an echo integration method, by using the parametric array, as an active sonar,
based on the principles of nonlinear interaction of acoustic waves. These arrays have a wide
range of operating frequencies and a narrow beam pattern in the practical absence of a side field.
This will improve the efficiency of search and evaluation of zooplankton and small fish accumulations, which is an important economic task. Theoretical prerequisites for the implementation of the
echo-integration method using nonlinear hydroacoustics are considered. Assumptions were made
about the uniformity of distribution of hydrobionts in the scattering volume, the independence of
object location from the directivity axis and a large accumulation of aquatic organisms compared
to the beam width of the parametric array. In the expression of determining the echo signal from
multiple sources it is proposed to use the beam pattern of the parametric array in spherical coordinates.