Order Modes Research Articles

Refractive Index Sensitivity Characterization of Tilted Fiber Bragg Grating Based Surface Plasmon Resonance Sensor

We have systematically investigated the refractive index (RI) sensing characterization of tilted fiber Bragg grating (TFBG) based surface plasmon resonance (SPR) sensors in terms of period and tilt angle of grating. The numerical analysis has revealed that the RI sensitivity of TFBG-SPR is linearly proportional to the grating period, and slightly improved with increasing the tilt angle of grating. Under the same normal grating period, the TFBG-SPR sensors with different tilt angles have the different cladding mode order range, which is responding to the different sensing ranges. Furthermore, we have fabricated the TFBG-SPR sensors with different periods and different tilt angles (5°, 7°, 10°, 12°, and 15°). Experimental results show that the larger normal grating period of TFBG is, the higher RI sensitivity of the SPR sensor is, in which the 10° TFBG-SPR sensors with the normal grating period of 529.37nm, 680.20nm have the RI sensitivity of 547.6nm/RIU, 723.6nm/RIU, respectively. And the TFBG-SPR sensors with different tilt angles slightly affect the RI sensitivity, but the sensors with different tilt angles have different sensing ranges, in which the RI sensitivity of TFBG-SPR sensors with the tilt angle of 7°, 10°, 12° are 545.5 nm/RIU, 547.6 nm/RIU, 549.1 nm/RIU in the RI range of 1.38-1.42,1.33-1.40,1.33-1.37 respectively. Finally, we have discussed the sensing resolution of TFBG-SPR sensor which the larger tilt angle and longer period could worsen the sensing resolution of TFBG-SPR sensor.

A Complex Mode Superposition Method Based on Hysteretic Damping Model for Mode Static Correction

Due to modal truncation, the dynamic responses calculated by the mode superposition method have some errors. In this paper, the source of truncation error of the complex mode superposition method for hysteretic damped systems with non-proportional characteristics is analyzed. It includes truncation errors of external excitation load and Hilbert transform term. With the increase of mode order, the ratio of excitation frequency to natural frequency gradually approaches zero. Combined with the expression of structural modal response caused by harmonic wave, the corresponding approximate expression of high-order modal response is obtained. Through quasi-static analysis, a complex mode superposition method of non-proportionally damped systems for mode static correction is proposed. Numerical examples show that when the ratios of the domain frequencies of the external excitation to the natural frequency of some high-order modes are small, the complex mode superposition method for mode static correction has a good effect.

Predicting the Heat Generation Rate in Large Format Pouch-Type Lithium-Ion Battery Cells for Automotive Applications

Accurate prediction of the heat generation rate of lithium ion batteries is critical for driving towards a cost effective and efficient design of a thermal management system for various applications.[1, 2] because of the increase in battery cell dimensions associated with an increase in battery cell capacity to drive towards a reduction in range anxiety for automotive applications, as well as more aggressive operating conditions that are typically seen in the automotive industry, such as direct current fast charge and sustained driving under load, heat generation at the cell level must be considered as spatially nonuniform during operation. Proper design of the thermal management system requires prediction[3] of the heat generation of the battery cell in both a lumped fashion for system sizing, as well as a distributed mode in order to focus cooling appropriately to decrease local temperature extremes. Local temperature extremes can adversely affect the aging of the battery cell due to the non-uniformities in electrochemical utilization of the active material, increased local reaction rates, and increased mechanical stresses in active materials.In this work, we detail our efforts to characterize the heat generation[4] of a battery cell under a variety of operating conditions, quantify the impact of temperature non-uniformities[5] on the aging of the battery cell, and experimentally[6, 7] evaluate the localized aging in the battery electrodes based on local temperature conditions. Here, we will describe the modeling methods developed to link operating conditions, aging, and heat generation with the electrochemical performance of the battery cell. A discussion of the model performance for relevant automotive applications will also be included.References M. Song, Y. Hu, S.-Y. Choe and T. R. Garrick, J Electrochem Soc, 167, 120503 (2020).Y. Hu, S.-Y. Choe and T. R. Garrick, Electrochim Acta, 362, 137124 (2020).M. Song, Y. Hu, S.-Y. Choe and T. R. Garrick, J Electrochem Soc, 169, 070502 (2022).Y. Hu, S.-Y. Choe and T. R. Garrick, Applied Thermal Engineering, 189, 116709 (2021).Y. Hu, S.-Y. Choe and T. R. Garrick, J Power Sources, 532, 231350 (2022).U. Janakiraman, T. R. Garrick and M. E. Fortier, J Electrochem Soc, 167, 160552 (2020).T. R. Garrick, J. Gao, X. Yang and B. J. Koch, J Electrochem Soc, 168, 010530 (2021).

Furthering Ontological Pluralism, Maybe: The Strange Case of the Microbial Recordings

This paper describes the trials and tribulations of drawing on Latour’s work on ontological pluralism ( An Inquiry into the Mode of Existence) to make sense of a series of recordings collected by participants in a sensorial urban walk focused on bacterial “field marks” that I developed with artist-researcher Louise Mackenzie. I explore the possibility that our inability fully account for the recordings should not be seen as failure but instead could be related to the generative power of compound intersections between modes of ordering. I propose that specific arrangements of mode of existences deploy the confusion that we experienced in listening to the microbial walk recordings. Drawing on Serres’s sensorial philosophy of knowledge, I suggest that caring for “neglected things” might entail attending also to incomplete, confused ways of being.

Phylogenomic and population genomic analyses reveal the spatial–temporal dynamics of diversification of the Nigella arvensis complex (Ranunculaceae) in the Aegean archipelago

The continental-shelf islands of the Aegean Sea provide an ideal geographical setting for evolutionary-biogeographical studies but disentangling the relationships between palaeogeographical history and the times, orders of modes of taxon divergence is not straightforward. Here, we used phylogenomic and population genomic approaches, based on orthologous gene sequences and transcriptome-derived SNP data, to reconstruct the spatial–temporal evolution of the Aegean Nigella arvensis complex (Ranunculaceae; 11 out of 12 taxa). The group’s early diversification in the Early/Mid-Pliocene (c. 3.77 Mya) resulted in three main lineages (Greek mainland vs. central Aegean + Turkish mainland/eastern Aegean islands), while all extant taxa are of Late Plio-/Early Pleistocene origin (c. 3.30–1.59 Mya). Demographic modelling of the outcrossing taxa uncovered disparate modes of (sub)speciation, including divergence with gene flow on the Greek mainland, para- or peripatric diversification across eastern Aegean islands, and a ‘mixing–isolation–mixing (MIM)’ mode of subspeciation in the Cyclades. The two selfing species (N. stricta, N. doerfleri) evolved independently from the outcrossers. Present-day island configurations are clearly insufficient to explain the spatial–temporal history of lineage diversification and modes of (sub)speciation in Aegean Nigella. Moreover, our identification of positively selected genes in almost all taxa calls into question that this plant group represents a case of ‘non-adaptive’ radiation. Our study revealed an episodic diversification history of the N. arvensis complex, giving new insight into the modes and drivers of island speciation and adaption across multiple spatiotemporal scales.

Degradation of binary mixtures of dyes by step-scheme quaternary photocatalyst in continuous flow-loop ultrasound assisted micro-photoreactor

The development and design of micro-scale photocatalytic systems to achieve the degradation of organic pollutants such as dyes to improve environmental conditions is very desirable. In the current study, a microfluidic-based ultrasound-assisted photocatalytic microreactor was used for degradation of a mixture of cationic dyes including RhB and MB in binary mode by quaternary CeO2/Co3O4/Ag/Ag3PO4 step-scheme (S- scheme) photocatalyst under visible LED light. Various characterizations were performed to determine the morphology and structure of the photocatalyst. The ultrasound-assisted photocatalytic micro-photoreactor shows a much higher degradation performance than the simple micro-photoreactor for the degradation of cationic dyes. Besides, the batch process shows higher photocatalytic activity compared to the micro-photoreactor under ultrasound-assisted process. In addition, the reaction constant of CeO2/Co3O4/Ag/Ag3PO4 composite in ultrasound assisted micro-photoreactor are about 0.0087 1/s and 0.0081 1/s (RhB and MB) which are almost 2.3 and 1.7 times higher than micro-photoreactor due to free radicals, ultrasonic waves and Dean vortices. The observation of findings illustrated the photocatalytic degradation of dyes by the as-prepared composite in various processes were in the order of batch mode > ultrasound assisted micro-photoreactor > micro-photoreactor. The strategy of micro-photoreactor with ultrasonic waves using photocatalytic composite to improve dye degradation performance can lead to the development of advanced micro-photoreactor based on photocatalytic composites with high performance for wastewater treatment applications.

Metasurface modulator of frequency diverse multi-mode OAM beams with equal divergence angle for coincidence imaging

Traditional multi-mode orbital angular momentum (OAM) beams suffer from low energy efficiency in detection since the divergence angle tends to increase with increasing order of the OAM mode. Thus, OAM beams with equal divergence angle are highly desirable. In this paper, a frequency-diverse multi-mode (FDMM) OAM modulator with approximately equal divergence angle is proposed. The modulator is composed of an OAM modulation metasurface and a spatial filter (SF) with narrow passband. Firstly, the OAM modulation metasurface is designed based on multiple ring-like regions with different radii in the metasurface aperture. Each mode of OAM beam is generated at a corresponding frequency point in one region. Thus, the metasurface aperture can generate different modes of OAM beams at different frequencies (i.e., FDMM OAM beams) simultaneously. Then, the SF with narrow passband is proposed through synthesizing multi-layer frequency selective metasurfaces, aiming to reduce interferences between different modes of OAM beams. Finally, the FDMM OAM modulator is realized by superposing the SF on the OAM modulation metasurface. The FDMM OAM modulator can generate six modes of OAM beams (i.e., , and modes) at 12.5 GHz, 13.0 GHz and 13.6 GHz, respectively. A multi-mode OAM coincidence imaging model based on the FDMM OAM modulator is established. The simulation and experiment results show that the proposed FDMM OAM modulator can be used for target reconstruction and the coincidence imaging performance can be improved assisted by an optimization algorithm.

Random vibration of sandwich beam with a shear thickening fluid core

The dynamic performances of a sandwich beam with a shear thickening fluid (STF) core subjected to a random excitation are investigated. First, the STF is prepared and a new constitutive model is proposed based on the oscillatory rheological measurements. Next, a flexural vibration model of the sandwich beam with an STF core under random load is developed, and a parametric study is carried out. It is found that the response frequencies and damping ratios for the first three modes of the beam increase with the standard deviation of the external random excitation. The sandwich beam with STF provides better damping for larger broadband excitation. Additionally, the beam with an STF core will produce a response both inside and outside the load frequency domain. Furthermore, an optimal thickness ratio for the structure that maximizes the damping ratio of the structure is identified. It is important to note that this optimal thickness ratio of the structure varies with the order of vibration modes. This research provides valuable insights into the design of structures using STF and also contributes to the development of dynamic constitutive models for STF.

Free vibration properties of beetle elytron plate: Composite material, stacked structure and boundary conditions

Beetle elytron plate (BEP), which is derived from the bionics of Trypoxylus dichotomus's elytra, is a typical lightweight and high-strength structure with superior and comprehensive mechanical properties. To promote the engineering application of BEPs, this paper explores the vibration characteristics of foam-filled fiber composite BEPs. Through the finite element method (FEM), structural parameters such as the length-to-width ratio, core height-to-thickness ratio, skin thickness and foam density influence the natural frequency and mode. Furthermore, the influence pattern of parameters (such as boundary conditions and the number of stacked layers) toward the first two orders of natural frequencies and modes of the BEP were investigated under controlled total height and controlled single layer height. The results indicate that 1) the ranking of structural parameters on the 1st order frequency from a strong to weak sequence is as follows: length-to-width ratio, core height-to-thickness ratio, foam density and skin thickness; for the 2nd order natural frequency: length-to-width ratio, skin thickness, foam density and core height-to-thickness ratio. 2) Generally, an increase in the length-to-width ratio will reduce the frequency of the BEP, and increases in the core height-to-thickness ratio and skin thickness will raise its frequency. Additionally, foam filling plays a decisive role in local deformation. 3) When the total height of the sandwich plate is controlled, the improvement of the boundary conditions can effectively boost its 2nd-order frequency (approximately 200%), but the 1st-order frequency can be significantly increased (approximately 140%) only when all four sides are improved. 4) In the case of controlling the height of the single layer of the sandwich plate, its frequency gradually increases with the increase in the number of stacked layers. However, when the constraints are weak or there are few stacked layers, increasing the number of stacked layers can effectively boost the vibration frequency. This paper provides references and suggestions for the design and application of sandwich structures, enriching the research on the mechanical properties of BEPs and establishing groundwork for promoting BEPs in engineering practices.

Automated Study of Electrophysical Properties of Polymeric and Composite Materials

The use of secondary resources and composites in modern polymer materials would make it possible to reduce the cost and change the physical and mechanical properties of the packaging material. The use of composites to impart new properties to polymers complicates the implementation of technologies for the production of products from them, which prevents the improvement of product quality. This is due to the lack of an accumulated database and methods of predictive determination of the obtained properties of composite materials and polymers produced with the use of secondary raw materials. (Research purpose) The research purpose is testing the methodology of automated determination of electrophysical parameters of polymer and composite thermoplastic materials. (Materials and methods) A resonant method of monitoring the electrophysical parameters necessary for an energy-efficient method of high-frequency electrothermal heating of polymers has been substantiated. We selected and modified with the installation of an automated monitoring and data collection system cumeter with a working chamber from a standard cell, retrofitted with a heating system and thermal insulation. (Results and discussion) The results of the use of an automated process of control and determination of electrophysical parameters of polymer and composite materials based on polypropylene, polyethylene with a composite of titanium dioxide were presented. The method of establishing analytical dependencies for calculating the correction coefficient when calculating the effect of thermal insulation material (dielectric cardboard) and air gap in the working capacitor on the even electrophysical parameters of the polymer and composite under study was shown. (Conclusions) The possibility of conducting automated studies to determine the dielectric properties of polymer and composite materials using the developed automated control system for the process of control, transmission, processing, visualization and storage of information about the dielectric properties of ε, ε», tgδ polymer and composite materials was substantiated. The heating temperature ranges of polymer and composite materials PP H030 GP/3 TS and 1060PE were identified in automatic mode in order to organize the most energy-efficient operating modes of high-frequency electrical equipment.

A Real-Time Monitoring System for Cable Tension with Vibration Signals Based on an Automated Algorithm to Sieve Out Reliable Modal Frequencies

Cables or suspenders are the critical force-transmitting components of cable-supported bridges, and their timely tension monitoring is consequently the most important issue in the corresponding structural health monitoring. However, very few works regarding the full automation of vibration-based tension estimation have been reported in the literature. To develop a monitoring system of cable tension based on real-time vibration signals, this research first employs an efficient stochastic subspace identification (SSI) method with tailored parameter selection to continuously identify the three frequencies of adjacent modes for the cables of Mao-Luo-Hsi Bridge. More importantly, an automated sieving algorithm is delicately established to obtain the stable modal frequencies by making the best of the specific modal frequency distribution for cables. The ratios between the frequency values identified from SSI analysis are exhaustively checked to systematically extract the qualified cable frequencies and decide their corresponding mode orders. The tension is finally computed with one available cable frequency according to the priority order predetermined by the statistics of identification rate. Demonstrated by analyzing the vibration signals measured from the stay cable of Mao-Luo-Hsi Bridge in real time for two full years, the effectiveness and robustness of this real-time monitoring system have been extensively testified. The long-term success rates for the immediate determination of dependable tension are found to be perfect for 15 of the 18 investigated cables. As for the other three cables, their corresponding success rates are still higher than 99.99% with very few cases of absent or false tension values.

The negative stiffness electromagnetic tuned inerter damper for damping enhancement of stay cables

Long stay cables may be subject to vortex-and rain-wind-induced vibrations. To suppress the two types of vibrations simultaneously, integrating the advantages of negative stiffness and inerter-based damper, a new negative stiffness electromagnetic tuned inerter damper (NSETID) is proposed in this study. The equivalent mechanical model of the NSETID is presented according to its working principle. On this basis, non-dimensional analytical equations of the cable with NSETID are developed. Subsequently, the optimum parameters of the NSETID are identified by optimizing the damping ratio of the tuned cable mode. The effects of the cable sag and flexural stiffness on the control performance and optimum parameters of the NSETID are also taken into consideration. In addition, the benefits and damping enhancement of the NSETID for mitigating single-mode and multi-mode cable vibrations are illustrated by comparing with tuned inerter damper (TID), negative stiffness damper (NSD), and negative stiffness inerter damper (NSID). Finally, the damping enhancement mechanism of the NSETID for cable multi-mode is explored through its stiffness and damping properties. The results highlight the superior damping enhancement capabilities of the NSETID in mitigating single-mode and multi-mode cable vibrations. The better control performance of the NSETID can be attributed not only to its negative stiffness behavior but also to the adaptability of its equivalent damping and negative stiffness coefficients to the cable mode order.

Mathematical model of air flow movement in a motorized filter respirator

Purpose. Development of a mathematical model of the air flow movement in a motorized filter respirator (hereinafter referred to as MFR), which allows ensuring the control of the fan parameters, taking into account external and internal influences on the duration of the protective action and favourable operating conditions. Methodology. To describe linear objects of the “input-output” type, it is convenient to use their transfer functions as mathematical models. In this case, to determine the mathematical description of the MFR operation, two tasks need to be solved. The first is related to finding the structure of the mathematical model, and the second involves determining the coefficients of the polynomials in the numerator and denominator of the transfer function that describes the motion of the air flow in the MFR. Findings. A mathematical model of airflow in a MFR has been developed in the form of a transfer function of the third order; it can be used to develop a pressure control system for the air in the under-mask space in accordance with the user’s work mode in order ensure comfortable working conditions. The presented mathematical model of airflow in the MFR differs from the existing approaches by taking into account the influence of the following external and internal parameters of the system on the performance indicators: the user’s work mode, atmospheric pressure, filter resistance, pressure drop in air ducts with the effect of air accumulation in the under-mask space based on the “capacity-resistance” principle. Numerical coefficients of the mathematical model of airflow in the air duct of the MFR have been determined, which allow adjusting the number of fan rotations according to the time of operation, the increase in resistance on the filters, and the operating mode. Originality. A correlation has been established between the external and internal parameters of the MFR: atmospheric pressure, pressure drop in the air duct, filter resistance, and the user’s work mode with the effect of air accumulation in the sub-mask space reflected according to the “capacity-resistance” principle. Practical value. The parameters of the mathematical model have been determined, which can be used when developing a control system for the airflow movement in the MFR: changes in air flow rate in accordance with different conditions of physical exertion of the user when performing professional activities.

A comprehensive study to reveal the potential of a more sustainable ultra-high performance enantioselective reversed-phase chromatography on Pirkle-type stationary phase, with Whelk-O1 as a case study

In this study, we aimed to make enantioselective chromatography more sustainable, more sensitive, and compatible with aqueous formulations analysis and ESI-MS. To achieve this, we examined the effects of transitioning from normal-phase chromatography (which uses hydrocarbon-based solvents) to reversed-phase chromatography (using mobile phases based on water) using broad-spectrum Whelk-O1 columns as a critical study. For the first time, we holistically compared the thermodynamics and kinetics of the two elution modes in order to answer the question of whether same-column chemistry can effectively separate the compounds even in reversed-phase mode and found, unexpectedly, that reversed-phase chromatography using acetonitrile as the organic modifier was competitive from a kinetic standpoint. We also evaluated the effectiveness of three organic modifiers simultaneously on a sample of 11 molecules already resolved in NP conditions with different resolutions and achieved a resolution value of 1.5 for 91% and a resolution value of 2 for 82% of cases. Finally, we separated three racemates (within a k factor of 9) using only 480 µL of solvent per chromatographic run on a millibore column of 1 mm I.D., demonstrating that our approach allows for greener chromatographic separations.

Controlling Three-Color Förster Resonance Energy Transfer in an Optical Fabry–Pérot Microcavity at Low Mode Order

We study three-color Förster resonance energy transfer (triple FRET) between three spectrally distinct fluorescent dyes, a donor and two acceptors, which are embedded in a single polystyrene nanosphere. The presence of triple FRET energy transfer is confirmed by selective acceptor photobleaching. We show that the fluorescence lifetimes of the three dyes are selectively controlled using the Purcell effect by modulating the radiative rates and relative fluorescence intensities when the nanospheres are embedded in an optical Fabry–Pérot microcavity. The strongest fluorescence intensity enhancement for the second acceptor can be observed as a signature of the FRET process by tuning the microcavity mode to suppress the intermediate dye emission and transfer more energy from donor to the second acceptor. Additionally, we show that the triple FRET process can be modeled by coupled rate equations, which allow to estimate the energy transfer rates between donor and acceptors. This fundamental study has the potential to extend the classical FRET approach for investigating complex systems, e.g., optical energy switching, photovoltaic devices, light-harvesting systems, or in general interactions between more than two constituents.

Thermalization of open quantum systems using the multiple-Davydov- D2 variational approach

Numerical implementation of an explicit phonon bath requires a large number of oscillator modes in order to maintain oscillators at the initial temperature when modeling energy relaxation processes. An additional thermalization algorithm may be useful in controlling the local temperature. In this paper we extend our previously proposed thermalization algorithm [M. Jaku\v{c}ionis and D. Abramavi\v{c}ius, Phys. Rev. A 103, 032202 (2021) ] to be used with the numerically exact multiple-Davydov-D2 trial wave function for simulation of relaxation dynamics and spectroscopic signals of open quantum systems using the time-dependent Dirac-Frenkel variational principle. By applying it to the molecular aggregate model, we demonstrate how the thermalization approach significantly reduces the numerical cost of simulations by decreasing the number of oscillators needed to explicitly simulate the aggregate's environment fluctuations while maintaining correspondence to the exact population relaxation dynamics. Additionally, we show how the thermalization can be used to find the equilibrium state of the excited molecular aggregate, which is necessary for simulation of the fluorescence and other spectroscopic signals. The thermalization algorithm we present offers the possibility to investigate larger system-bath models than was previously possible using the multiple-Davydov-D2 trial wave function and local heating effects in molecular complexes.

Robust superdirective beamforming for arbitrary sensor arrays

This paper presents a method of designing robust superdirective beamformers for arbitrary sensor arrays. First, the optimal weighting vector is transformed into an equivalent form based on the eigen–decomposition of the noise correlation matrix in an isotropic uniform noise field, and its entries will be indexed using mode orders instead of element numbers. Second, a parameter is weighted at the maximum–order entry in the modified weighting vector. The beampattern, directivity factor, and error sensitivity function can be expressed as functions of the parameter. Adjusting the parameter will achieve arbitrary–order superdirective beampatterns with different directivity factors or error sensitivity functions. Third, the closed–form expression of the parameter can be derived given a desired directivity factor or error sensitivity function. The final robust broadband superdirective beampatterns can then be readily synthesized. The proposed method, which is an extension of that previously proposed for circular sensor arrays, provides flexible schemes to designing robust broadband superdirective beamformers for arbitrary arrays in simulations and experiments.

A Compact Polarization MMI Combiner Using Silicon Slot-Waveguide Structures.

The study of designing a compact transverse electric (TE)/transverse magnetic (TM) polarization multimode interference (MMI) combiner based on silicon slot-waveguide technology is proposed for solving the high demands for high-speed ability alongside more energy power and minimizing the environmental impact of power consumption, achieving a balance between high-speed performance and energy efficiency has become an important consideration in an optical communication system. The MMI coupler has a significant difference in light coupling (beat-length) for TM and TE at 1550 nm wavelength. By controlling the light propagation mechanism inside the MMI coupler, a lower order of mode can be obtained which can lead to a shorter device. The polarization combiner was solved using the full-vectorial beam propagation method (FV-BPM), and the main geometrical parameters were analyzed using Matlab codes. Results show that after a short light propagation of 16.15 μm, the device can function as TM or TE combiner polarization with an excellent extinction ratio of 10.94 dB for TE mode and 13.08 dB for TM mode with low insertion losses of 0.76 dB (TE) and 0.56 dB (TM) and the combiner function well over the C-band spectrum. The polarization combiner also has a robust MMI coupler length tolerance of 400 nm. These attributes make it a good candidate for using this proposed device in photonic integrated circuits for improving power ability at the transmitter system.

Research on The Internal Control Framework of Large State-owned Enterprises Under Information-based Environment

In the information society and digital era, the information construction of the enterprise internal control framework is particularly important for enterprises to enhance their endogenous power and improve their management efficiency. In order to achieve increasingly powerful control functions and build an efficient overall enterprise internal control framework, we must rely on scientific and precise control means and efficient operation mechanisms. Under such circumstances, large state-owned enterprises should absorb and apply more advanced management concepts and actively innovate and optimize their management mode in order to improve their management level and enhance their comprehensive competitiveness and thus achieve long-term development in the fierce market competition. An important way for large state-owned enterprises to strengthen their management is to build an internal control system. The internal control system can regulate the operation of power, strengthen risk prevention and supervision of internal personnel and be a stimulus to large enterprises to reduce operating costs and increase economic efficiency.

Improvement of the pressure dynamics model in the mask for a powered air purifying respirator as an object of control

Purpose. Justification of the need to improve the simulated model of the powered air-purifying respirator, substantiating the need for planning and conducting additional experiments. Determination of parameters and confirmation of the adequacy of the simulation model to the object of control – a powered air-purifying respirator. Methodology. The research was carried out on an experimental setup by means of an active experiment. To obtain a static characteristic, a sequential increase in the control effect – the speed of rotation of the fan in steps of 200 rpm was performed, and the actual value – pressure in the respirator mask – was recorded. Based on the experimental data, a statistical characteristic was constructed and the dependence of the model amplification factor on the control influence was determined. Verification of the obtained model for adequacy to the control object was performed according to Fisher's adequacy criterion. Findings. According to the results of the study, it was established that the static characteristic of the powered air-purifying respirator according to the channel "speed of rotation of the fan – pressure in the mask" is close to linear, and the amplification factor depends on the value of the control influence. Based on the analysis of the received data, the simulation model of the powered air-purifying respirator was improved. Originality. It was established that the static characteristic of the powered air-purifying respirator in the defined range of control influence is non-linear and the amplification factor depends on the speed of rotation of the fan blades. Practical value. The dependence of the amplification factor on the speed of rotation of the fan blades was determined. Adequacy of the improved simulation model to the control object is 92%. An improved simulation model of a powered air-purifying respirator allows you to perform a study of operating modes in order to determine the requirements for controlling the air supply process to the mask and further synthesis of the control system using various types of regulators.