The results of key comparison are the most convincing and objective indicator of confirmation of the correctness and accuracy of the newly developed measurement method. The results of comparison and measurement methods applied at the second key comparison of national standards of the unit of sound pressure in water CCAUV.W-K2, organized by the Consultative Committee for Acoustics, Ultrasound and Vibration of the International Committee for Weights and Measures, are described. A feature of the comparison is that the calibration range has been expanded into the low frequency region by two octaves compared to the first key comparison CCAUV.W-K1. The results of the CCAUV.W-K2 comparison were considered successful. Important scientific results of participation in the comparison were confirmation of: the correctness of the hydrophone free-field calibration methods developed at VNIIFTRI (at ultra-low frequencies for a sound-reflecting water tank and in the noise reverberant sound field of the water tank), the equivalence of the calibration results when radiating signals of various types: chirp, noise and ton-burst. In the process of performing control calibrations, the pilot laboratory discovered violations of the stability of the reference hydrophone of comparison. When comparing the results obtained by participants, there was an increase in the discrepancy between the results in the frequency range 60–100 kHz, which is considered the least problematic.

Quantum dots (QDs) are semiconductor nanocrystals with a size in the range of 1–10 nm. They are created on the basis of inorganic semiconductor materials Si, InP, CdSe, etc., and are coated with a stabilizer monolayer. QDs have unique optical, electrical, electrochemical, and catalytic properties. The crystal core of a quantum dot contains about 100–100 000 atoms. Quantum dot size is comparable to the wavelength in the material on the basis of which it is made. Inside a quantum dot, the potential energy of an electron is lower than outside it, and thus the motion of the electron is limited in all three dimensions. The energy levels of electrons inside a quantum dot are discrete and are separated by regions of forbidden states. The behavior and properties of these objects are described not by classical physics, but by quantum mechanics. The current review focuses on applications of QDs such as providing high-quality bioimaging of tumors in vitro and in vivo, visualization of drug transportation, targeted drug delivery, photothermal and photodynamic therapy, cell sorting activated by fluorescence, and use in biosensors. Emphasis is placed on the technology of accurate detection and inhibition of SARS-CoV-2 using quantum dots.

The work is devoted to the use of methods of applied mathematics and statistics for the formalization and mathematical modeling of the structure of shark skin as a prototype of new polymer materials for shipbuilding purposes. A technique for mathematical modeling of biological objects is described, and a method for using a biomimetic approach for the design of planar composite polymer materials with improved lyophilic adhesion properties is proposed. Because of studying images of shark skin obtained using high-resolution optical (HRO) and scanning electron (SEM) microscopy, we found that its texture is anisotropic. Quantitative analysis of BOM and SEM images made it possible to rationalize the choice of synthetic digital models intended for simulation prototyping of maximally and minimally texturally isotropic polymer samples using 3D printing and gas-phase surface modification.

The article considers the problem that arises during the amplitude-phase calibration of hydrophones by the reciprocity method and consists in the violation of the consistency of the hydrophone characteristics specified by the manufacturer. Violation of the indicated consistency of characteristics is due to the need to determine the phase-frequency characteristic when calibrating the hydrophone. The manufacturer sets the dimensions of the hydrophone receiving part and the position of the acoustic center according to the drawing of the receiving part and thereby replaces the acoustic parameters with geometric ones. To restore the consistency of the characteristics, it is proposed to determine the position of the acoustic center and the equivalent size of the hydrophone receiving part from the results of acoustic measurements. It is shown that the displacement of the hydrophone acoustic center relative to its geometric center is a typical phenomenon, and the geometric and acoustically measured dimensions of the active element can differ. To ensure the unity of acoustic measurements, it is proposed to introduce the concept of an equivalent radius and to clarify the concept of the hydrophone acoustic center, as well as to standardize the methods of their experimental determining. The results obtained will be useful in monitoring the phase responses of elements of hydroacoustic antennas for various purposes, ensuring the identity of the phase-frequency characteristics of the vector receivers measuring channels, in solving problems related to restoring the acoustic signal shape by the recorded voltage at the receiver output and other various applications, including marine ecology, medical ultrasound studies, etc.

Various approaches to the formulation of the definition of an acoustic center of a transducer and the problems arising when using them for experimental determination of the acoustic-center position are considered. The reasons for which the formulation and the corresponding method for determining the position of the acoustic center of a microphone are not suitable for a hydrophone are discussed. An experiment is described that demonstrates the proposed method for experimentally determining the position of the acoustic center of a hydrophone during its phase calibration by the reciprocity method.

Initiated by COOMET TC 1.2 "Acoustics, Ultrasound, Vibration," bilateral pilot comparisons of amplitude– phase calibrations of hydrophones in the frequency range 10–500 kHz COOMET 786/RU-a/19 between the Hangzhou Research Institute of Applied Acoustics (HAARI) and the Russian Metrological Institute of Technical Physics and Radio Engineering (pilot laboratory) are described. Characteristics of reference hydrophones, data on standard facilities and calibration methods, results of calibrations, and assessments of reference levels of comparisons are provided. The results of comparisons are discussed. The problems that influenced the results of comparisons are mentioned. The correctness of the measurement methods used by the participants of the comparisons, including the method of calculating the frequency dependence of the argument of hydrophone complex sensitivity on the experimental frequency dependence of the modulus of its sensitivity, has been confirmed. The results of the pilot comparisons were found to be satisfactory. When discussing the results of comparisons at the COOMET TC 1.2 meeting, it was proposed to conduct additional comparisons of the results of amplitude–phase calibrations in an expanded composition of participants. The results obtained allow verifying the correctness of the adopted new technical solutions, working out methods for performing measurements and post-processing of the data obtained, identifying and numerically assessing sources of uncertainty, and also establishing previously unaccounted sources of uncertainty when improving primary standards.

The problem of analytical representation of the experimental complex frequency response of a hydrophone based on a model consisting of a lead line and a minimum-phase component is considered. The model takes into account the resonant properties of the hydrophone and the effect of sound diffraction on the active element. Algorithms for approximation of the complex frequency response by a fractional-rational function of a complex variable based on the data of the amplitude-frequency and (or) phase-frequency characteristics of the hydrophone are proposed. Examples of application of algorithms for processing experimental frequency characteristics of measuring hydrophones are given. The results obtained will simplify the calibration and greatly reduce the dimension of calibration data while maintaining the accuracy characteristic of working measuring hydrophones.

The need to ensure the possibility of widespread use of electronic and mobile health-saving technologies requires not only the formation of an appropriate information technology infrastructure and the development of effective algorithms for processing a large amount of personal information. Development of medical devices for recording physiological processes also involves the creation of innovative biologically compatible materials that allow sensors and medical sensors to work continuously in 24/7 mode. Taking into account the long-term positive experience of using large-capacity thermoplastics and elastomers in medical equipment, it seems promising to use the corresponding polymers as the main materials of wearable electronics for medical purposes. At the same time, to ensure the biological compatibility of the materials under discussion, it is necessary to minimize the possibility of the development of pathogenic microorganisms on surfaces in contact with living tissues. This type of pathogenic organisms (pathogens of a number of dangerous diseases – mycoses) includes some types of microscopic fungi - micromycetes (in particular, Aspergillus niger van Tiegem; Aspergillus terreus Thom; Penicillium cycopium Westling). The article examines the effect of surface modification by gas-phase fluorination on the nature and degree of development of a mixed colony of micromycetes on the surfaces of experimental samples made of several types of thermoplastics (polyvinyl chloride, polypropylene, low-density polyethylene, polyethylene terephthalate) and elastomers (butyl- and butadiene-nitrile rubbers, as well as ethylene, propylene and dicyclopentadiene copolymers). The nature and degree of development of colonies are quantitatively described using the original methodology developed earlier. The effect of fluorination on the nanotexture and chemical composition of the surface and near-surface layers of experimental samples was demonstrated using scanning electron microscopy (SEM) and IR Fourier spectroscopy (IRFS). The dynamics and efficiency of fluorination are described using a linearized hyperbolic model, the parameters of which are set by the least squares method.

Investigating the reliability of the hydrophone model proposed in VNIIFTRI, consisting of an advance line and a minimum-phase part, including sound diffraction effect and resonance properties of the active element, is one of the COOMET 786/RU/19 pilot comparisons' responsibilities. This model allows for inverse operation, and the employment of the Hilbert transform to generate a phase-frequency response from the amplitude-frequency response. This study presents experimental results from the facilities of the State Primary Standard of units of acoustic pressure and vibrational velocity in an aqueous medium GET 55-2017. Obtaining the phase-frequency response for an acoustic center of the receiver is not essential for numerous practical applications. Therefore it is sufficient to determine the shape of the phase-frequency response using far less laborious methods.

Внедрение информационных систем направлено на повышение финансовых показателей компании, создание прозрачной системы отчетности и улучшение многих других конкурентно значимых факторов. Однако получение данных преимуществ не отрицает сложность принятия решения о реализации или об отказе от реализации конкретного ИТ-проекта. Общая стоимость владения информационной системой на протяжении всего жизненного цикла, как правило, не рассматривается в сопоставлении с предполагаемыми выгодами от использования системы, в связи с неопределенностью таких выгод. Относительная определенность подходов и методов присутствует только в части затрат, как для априорной (плановой), так и апостериорной (фактической) оценки. Возможно достаточно точное определение как капитальных, так и операционных затрат. Косвенное определение положительного влияния информационной системы на деятельность организации также представляется возможным. Однако общепринятых методов анализа предполагаемого положительного эффекта от реализации ИТ-проекта в настоящее время не существует. При этом крупные компании, в соответствии с требованиями соответствующих регуляторов и/или в связи с внутренними управленческими соображениями выстраивают систему управления рисками для определения уровня возможностей, потерь и предотвращения наступления неблагоприятных событий. В данном исследовании рассматривается возможность применения подхода к анализу эффективности внедряемой информационной системы на основе снижения рисков компании, ведущих к уменьшению экономических выгод. При этом принимаются во внимание внутренние риски информационной системы, возникающие при установке системы, ее эксплуатации и при завершении работы с системой.

The implementation of information systems is aimed at improving the financial performance of a company, creating a transparent reporting system and improving many other competitive factors. However, the acquisition of these benefits does not negate the complexity of making a decision whether or not to implement a particular IT project. The total cost of ownership of the information system throughout the life cycle is usually not considered in comparison with the expected benefits from the use of the system, due to the uncertainty of such benefits. Comparative certainty of approaches and methods is present only in terms of costs, both for a priori (planned) and a posteriori (actual) assessment. It is possible to determine both capital and operating costs accurately enough. Indirect definition of the positive influence of an information system on the activity of the organization also seems possible. However, there are currently no generally recognized methods for analyzing the expected positive effect of an IT project. At the same time, large companies, in accordance with the requirements of the respective regulators and / or due to internal management considerations, build a risk management system to determine the level of capabilities, losses and to prevent adverse events. This study considers the feasibility of an approach to analyze the effectiveness of the implementation of the information system on the basis of the company’s risk reduction, leading to a decrease in economic benefits. It takes into account the internal risks of the information system that occur during the installation of the system, its operation and the termination of work with the system.

The absence of a common and universal approach to IT project management allows us to formulate a problem to analyze and study when choosing the most efficient project management methodology. The relatively small number of scientific works summarizing practical experience of a theoretical approach allowed us to formulate a generalized mathematical model for a common IT project lifecycle estimation in this work using waterfall, agile or hybrid approaches for the project management. Based on the advantages and disadvantages of existing methodologies that we revealed, it appears that use of agile approaches within stages of the cascade methodology approach improves the process of IT project management compared to a pure cascade implementation. Moreover, the recursive application of an iterative approach at certain stages of the project implementation worsens the characteristics of the project life cycle and can be used only to reduce a certain class of project risks. The results of our study allow us to propose a semi-empirical method for project planning estimation accuracy and attainability of the declared project implementation characteristics. All of this should have a positive impact on the effectiveness of the IT project management strategy choice.

Отсутствие общего и универсального подхода к управлению ИТ-проектами позволяет сформулировать задачу анализа и изучения проблемы выбора наиболее эффективной методологии проектного менеджмента. На основе относительно небольшого числа работ по обобщению практических кейсов на уровне теоретических представлений в данной статье в общем виде показаны оценочные математические модели жизненного цикла абстрактного ИТ-проекта, планируемого к реализации с помощью каскадного, итеративного и сочетающего их (гибридного) подходов. На основании выделенных преимуществ и недостатков каждой из существующих методологий показано, что дополнительное применение итеративных подходов на отдельных этапах реализации каскадной методологии в некотором смысле улучшает процесс реализации ИТ-проекта по сравнению с чисто каскадной реализацией. При этом рекурсивное применение итеративного подхода на отдельных этапах реализации проекта ухудшает характеристики жизненного цикла проекта и может применяться исключительно для снижения определенного класса проектных рисков. По результатам исследования предложен полуэмпирический способ оценивания качества планирования проекта и оценки достоверности декларируемых разработчиком характеристик реализации проекта, что должно положительным образом сказаться на эффективности выбора стратегии управления ИТ-проектом.

Currently, there is a widespread introduction of quantum technologies in human activity. The prospects of quantum technologies use for the needs of biomedicine are considered. The necessity of the development of new quantum technologies and methods for organizing the processing and analysis of large biomedical data is substantiated. Opportunities and prospects of using modern quantum computers for the needs of biomedicine are being analyzed. The prospects for the use of quantum sensors in biomedicine are discussed. The possibility of using quantum communication lines in the near future to transmit confidential personalized biomedical information is being considered. Prospects for using quantum dots for the purpose of killing both multidrug-resistant bacteria and cancer cells are discussed.

A measuring facility for reproducing a unit of sound pressure at frequencies of 1–500 Hz in the temperature range of 0.5–35 °С with excessive static pressures up to 60 MPa is described. The measuring facility was created in order to expand the functionality of the State primary standard GET 55-2017. The expediency of simulated ocean conditions in GET 55-2017 under hydrophone calibration, the principles of operation and the metrological characteristics of the measuring facility are discussed. Features of the measuring procedure for calibrating the hydrophone are given.

We present information about a standard installation used for the calibration of hydrophones at frequencies of 0.1–3.0 MHz. The installation is created with an aim to extend the frequency range of the GET 55-2017 State Primary Standard to the region of high-frequency ultrasound. The necessity of development of this installation is justified. We briefly consider basic principles of its operation and the possibilities of measurements. The requirements to the characteristics of ultrasonic transducers are discussed. In the choice of standard transducers, we give priority to their time stability because, in the course of transmission of the unit with the help of a tone signal, the uniformity of the frequency characteristic of sensitivity of the transducer is not of primary importance. To reduce the influence of directivity, we use a precise four-coordinate system of positioning of the transducers, which includes the possibility of control of their mutual positions with the help of a laser beam. We also consider the problems connected with the possibility of passing to higher frequencies.

We present the results of comparison of national standards of the units of sound oscillation velocity of water particles within the range from 5 Hz to 10 kHz performed by the Hangzhou Applied Acoustics Research Institute (Pilot Laboratory) and the All-Russia Research Institute of Physicotechnical and Radio Measurements (VNIIFTRI) (COOMET 646/RU/14 Pilot Comparisons). The calibration capabilities of the participants were evaluated according to the results of measurements of the sensitivity of oscillation-velocity receivers: KGP-10, VHS56, and VHS90. At frequencies varying from 5 Hz to 500 Hz, inclusively, the calibrations were performed in a chamber as a result of comparison with a reference hydrophone performed by the method of oscillating water column. At frequencies higher than 500 Hz, we used the measuring procedure of the reciprocity method in the free field of traveling spherical sound waves. No significant inconsistencies in the calibration results were discovered at any frequency used for comparisons. The maximal discrepancies between the values of sensitivity obtained by the participants did not exceed 1.2 dB.