High Kinetic Energy Research Articles

Numerical Investigations of Outer-Layer Turbulent Boundary Layer Control for Drag Reduction Through Micro Fluidic-Jet Actuators

Drag reduction through turbulent boundary layer control (TBLC) is an essential way to develop green aviation technologies. Compared with traditional approaches for drag reduction, turbulence drag reduction is a relatively new technology, particularly for skin friction drag reduction, and it is becoming a hotspot problem worldwide. This paper focuses on the research of micro fluidic-jet actuators used for outer-layer boundary layer control with high-performance computing (HPC). This study aims to reduce turbulent drag by reshaping the flow structure within the turbulent boundary layer. To ensure the calculation accuracy of the core region and reduce the consumption of computing resources, a zonal LES/RANS strategy and WMLES method are proposed to simulate the effects of fluidic-actuators for outer-layer boundary control, in which high-performance computing has to be involved. The studies are performed on the classical zero-gradient turbulent flat plate cases, in which three different control strategies named “W-control,” “V-control,” and “VW-control” are used and compared to study the effects of drag reduction under a low Reynolds number at Reτ = 470 and a higher Reynolds number at Reτ = 4700. The mechanism for drag reduction is analysed via a pre-multiplied spectral method and a parallel dynamic mode decomposition (DMD) method. The results show that the present approach can effectively simulate the outer-layer turbulent boundary control where the “V-control” with the fluidic-jet actuator array behaves well to achieve an average drag reduction (DR) rate of more than 5% for the high Reynolds number case of the flat plate boundary layer. The high Reynolds shear stress and turbulent kinetic energy distribution in the boundary layer region show an obvious uplift under the effects of actuators, which is the main mechanism for drag reduction.

Effects of vegetation density on flow, mass exchange and sediment transport in lateral cavities

Large-Eddy Simulations (LES) were used to investigate the hydrodynamics and mass transfer between the flow in the main channel and a vegetated lateral cavity. Fourteen vegetation densities (0 to 10.65 %) were tested, revealing two distinct hydrodynamic patterns. For cavities with low vegetation density (a < 3.99 %), one primary gyre in contact with the interface between main channel and cavity with high velocity was formed; the thickness of the mixing layer grew longitudinally along the interface, and regions with high vorticity and turbulence kinetic energy appeared at the interface and inside the cavity. For cavities with high vegetation density (a > 3.99 %), two gyres in contact with the interface with low velocity were formed, the thickness of the mixing layer did not grow, and the vorticity and turbulence kinetic energy were low inside the cavity. The mass transport presented the same threshold value as the hydrodynamics (a = 3.99 %). For cavities with low vegetation density, a fast mass transfer occurred through the interface between the main channel and cavity and inside the cavity, while the opposite was observed for cavities with high vegetation density. Finally, the modelled hydrodynamics was used to infer possible sediment deposition patterns and flow resistance.

SOLID PARTICLE AIRJET EROSION AND CORROSION BEHAVIOR OF AA6063 ALUMINUM ALLOY

Aluminum alloy 6063 has excellent mechanical properties and it is used in automotive industries. This research focuses on solid particle airjet erosion behavior in different input parameters such as mass flow rate of 2, 3, and 4 gm/min, impingement angle of 30[Formula: see text], 60[Formula: see text], and 90[Formula: see text] and erodent velocity of 100, 150, and 200 m/s. The alumina erodent is mixed with an airjet which acts as an impingement fluid jet. Taguchi was utilized for investigating the influence of the process parameter on erosion rate, and ANOVA was performed to evaluate the parameter contribution. The impingement velocity is the most significant parameter to reduce the erosion rate rather than the impingement angle and the mass flow rate. The increase in velocity of the impingement fluid jet accelerates the erosion rate due to the high kinetic energy impact. The desirability approach is used to optimize the input parameters. At 99% confidence levels, the models were considered significant. The importance of the factor is increased by a reduced [Formula: see text]-value. From the overall analysis, the optimum conditions of solid particle airjet erosion are impingement angle of 90[Formula: see text], erodent velocity of 100 m/s and erodent flow rate of 2 gm/min. Utilizing the cyclic sweep approach, corrosion behavior and NaCl solution are involved in the test of AA6063. As the corrosion current density increased, the corrosion potential became more positive.

Numerical investigation the shape of groove on tip leakage vortex suppression of a NACA0009 hydrofoil

To investigate the effect of different bionic grooves on the tip leakage vortex, four bionic grooves with different shapes were designed, which are semicircular, rectangular, triangular and trapezoid. The streamline, pressure, vortex strength and turbulence kinetic energy were analyzed to clarify the suppression mechanism. When the groove is arranged, the velocity of vortex center and the area of high-intensity vortex area decrease. The vortex strength in the triangular groove is higher than other groove shapes. The pressure in the center of the tip leakage vortex core increases. The low pressure area reduces obviously, which is the smallest in the trapezoidal groove condition. The turbulent kinetic energy in the main flow field increases, but decreases in the tip clearance. The high turbulent kinetic energy region is divided into small pieces by the bionic groove, which is the smallest in the rectangular groove condition. The bionic groove leads to the decrease in lift-to-drag ratio, which is the largest in the semicircular groove and smallest in the rectangular groove condition.

Heterogeneous Integration of Graphene and HfO2 Memristors

AbstractThe past decade has seen a growing trend toward utilizing (quasi) van der Waals growth for the heterogeneous integration of various materials for advanced electronics. In this work, pulsed‐laser deposition is used to grow HfO2 thin films on graphene/SiO2/Si. As graphene is easily damaged under standard oxide‐film deposition conditions, the process needs to be adjusted to minimize the oxidation and the collision‐induced damage. A systematic study is conducted in order to identify the crucial deposition parameters for diminishing the defect concentration in the graphene interlayer. For evaluating the quality of graphene, it is mainly relied on data obtained from Raman spectroscopy, using approaches beyond the Tuinstra‐Koenig relation. The results show that the defects are mainly a consequence of the high kinetic energy of the plasma‐plume particles. Using a relatively high Ar process pressure, a sufficiently low defect concentration is ensured, without compromising the quality of the HfO2 thin film. This enabled us to successfully prepare memristive devices with a filamentary type of switching, utilizing the graphene layer as a bottom electrode. The findings of this study can be easily transferred to other systems for the development of oxide electronic devices.

Molecular dynamics study of boiling heat transfer in nanochannels under capillary flow

The increasing heat flux of electronic devices poses significant challenges in thermal management. Passive heat dissipation technology based on capillary drive has been widely concerned because it does not require external driving force and stability. However, due to the small size of the internal capillary structure, typically in the micro and nano scales, and the significant scale effect, further research is needed to understand the mechanism of internal boiling heat transfer. This study systematically investigates the boiling process of liquid in nanochannels under capillary flow with varying wettability using molecular dynamics simulations. It is found that increasing the energy coefficient (c) causes a greater accumulation of atoms near the wall, thereby enhancing the efficiency of solid–liquid heat transfer. The bubble has a larger stable volume as c increases and will burst in the case of high c. As c increases, the region of high potential and kinetic energy expands more rapidly, reducing the time it takes for bubble nucleation and rupture. The behavior of bubbles is significantly influenced by capillary flow, which is also influenced by wettability. When c = 0.9, the flow velocity reaches its maximum before bubble nucleation occurs. It leads to a more homogeneous heat transfer, resulting in a higher location of bubble nucleation. Furthermore, the presence of capillary forces increases the average potential energy of surrounding liquid atoms, thereby enhancing the growth rate of the bubble. This study provides a theoretical basis for the optimal design of capillary-driven two-phase heat dissipation devices.

Vortex dynamics characteristics in the tip region based on Wray–Agarwal model

In order to solve the blockage effect and energy dissipation phenomenon caused by cavitation in the low-pressure vortex core region, this paper analyzes the spatial evolution of vorticity intensity and turbulent kinetic energy intensity under different cavitation conditions based on the Wray–Agarwal (WA) model. First, the tip leakage flow characteristics are studied, the evolution of vorticity and vorticity intensity is analyzed, then the distribution of turbulent kinetic energy distribution in the blade tip region is studied, and finally, the vorticity transport characteristics of the tip region are analyzed. It is found that the tip leakage rate is less affected by the vortex cavitation of the tip leakage, and there is a strong interaction between the leakage flow at the tip leading edge and the trailing edge, and the separation vortices and low-speed regions formed in the end-wall region cause blockage of the flow passage. Low pressure causes cavitation to cover most regions of the suction surface, inhibiting the formation and development of the tip leakage vortices. The distribution range of high turbulent kinetic energy region is almost the same as that of high-vorticity region, and there is a positive correlation between the two intensities. Severe cavitation causes the high turbulent kinetic energy region at the outlet of the flow passage to develop in the radial and axial directions of the impeller, which increases the turbulent dissipation and energy loss. The change of vorticity transport intensity caused by cavitation is mainly reflected in the expansion contraction term, and the Coriolis force term plays a dominant role in the vorticity transport process. This paper provides a reference for further improving the performance of mixed-flow pumps.

Exploring the ultrafast and isomer-dependent photodissociation of iodothiophenes via site-selective ionization.

C-I bond extension and fission following ultraviolet (UV, 262 nm) photoexcitation of 2- and 3-iodothiophene is studied using ultrafast time-resolved extreme ultraviolet (XUV) ionization in conjunction with velocity map ion imaging. The photoexcited molecules and eventual I atom products are probed by site-selective ionization at the I 4d edge using intense XUV pulses, which induce multiple charges initially localized to the iodine atom. At C-I separations below the critical distance for charge transfer (CT), charge can redistribute around the molecule leading to Coulomb explosion and charged fragments with high kinetic energy. At greater C-I separations, beyond the critical distance, CT is no longer possible and the measured kinetic energies of the charged iodine atoms report on the neutral dissociation process. The time and momentum resolved measurements allow determination of the timescales and the respective product momentum and kinetic energy distributions for both isomers, which are interpreted in terms of rival 'direct' and 'indirect' dissociation pathways. The measurements are compared with a classical over the barrier model, which reveals that the onset of the indirect dissociation process is delayed by ∼1 ps relative to the direct process. The kinetics of the two processes show no discernible difference between the two parent isomers, but the branching between the direct and indirect dissociation channels and the respective product momentum distributions show isomer dependencies. The greater relative yield of indirect dissociation products from 262 nm photolysis of 3-iodothiophene (cf. 2-iodothiophene) is attributed to the different partial cross-sections for (ring-centred) π∗ ← π and (C-I bond localized) σ∗ ← (n/π) excitation in the respective parent isomers.

Simulating high-pressure surface reactions with molecular beams.

Using a reactive molecular beam with high kinetic energy (Ekin), it is possible to speed gas-surface reactions involving high activation barriers (Eact), which would require elevated pressures (P0) if a random gas with a Maxwell-Boltzmann distribution is used. By simply computing the number of molecules that overcome the activation barrier in a random gas at P0 and in a molecular beam at Ekin = Eact, we establish an Ekin-P0 equivalence curve, through which we postulate that molecular beams are ideal tools to investigate gas-surface reactions that involve high activation energies. In particular, we foresee the use of molecular beams to simulate gas surface reactions within the industrial-range (>10 bar) using surface-sensitive ultra-high vacuum (UHV) techniques, such as X-ray photoemission spectroscopy (XPS). To test this idea, we revisit the oxidation of the Cu(111) surface combining O2 molecular beams and XPS experiments. By tuning the kinetic energy of the O2 beam in the range of 0.24-1 eV, we achieve the same sequence of surface oxides obtained in ambient pressure photoemission (AP-XPS) experiments, in which the Cu(111) surface was exposed to a random O2 gas up to 1 mbar. We observe the same surface oxidation kinetics as in the random gas, but with a much lower dose, close to the expected value derived from the equivalence curve.

Assessment of the throwing effect of material fragments resulting from the detonation of explosive materials

The modelling of the throw effect of material fragments following the detonation of explosive materials with a harmful effect on the human component and/or nearby industrial/civil targets is based on the quantification of the impact of the throwing speed and mass of the material fragments. Models developed to generate trajectory calculations for ranges of mass, launch angles and launch velocity based on Monte Carlo simulations are sensitive to the predetermined ranges assigned to each trajectory variable, requiring long time intervals to run the simulations at the time of analysis and IT resources to match. Following the production of an explosion-type event, thousands of individual fragments characterized by their own mass and velocity parameters can be generated, resulting individual energy values that can be taken into account in a quantitative risk assessment, by grouping them into ten distinct classes, thus: Class 1st represents fragments with the highest kinetic energy and/or mass, and class 10th represents fragments with the lowest kinetic energy and/or mass. The paper will highlight the ten distinct classes of the kinetic energy parameter, with the maximum, average and minimum values for each class, as well as the average mass for each detached fragment associated with the energy classes.

Shell-dependent photofragmentation dynamics of a heavy-atom-containing bifunctional nitroimidazole radiosensitizer.

Radiation therapy uses ionizing radiation to break chemical bonds in cancer cells, thereby causing DNA damage and leading to cell death. The therapeutic effectiveness can be further increased by making the tumor cells more sensitive to radiation. Here, we investigate the role of the initial halogen atom core hole on the photofragmentation dynamics of 2-bromo-5-iodo-4-nitroimidazole, a potential bifunctional radiosensitizer. Bromine and iodine atoms were included in the molecule to increase the photoionization cross-section of the radiosensitizer at higher photon energies. The fragmentation dynamics of the molecule was studied experimentally in the gas phase using photoelectron-photoion-photoion coincidence spectroscopy and computationally using Born-Oppenheimer molecular dynamics. We observed significant changes between shallow core (I 4d, Br 3d) and deep core (I 3d) ionization in fragment formation and their kinetic energies. Despite the fact, that the ions ejected after deep core ionization have higher kinetic energies, we show that in a cellular environment, the ion spread is not much larger, keeping the damage well-localized.

Non-covalent planarizing interactions yield highly ordered and thermotropic liquid crystalline conjugated polymers.

Controlling the multi-level assembly and morphological properties of conjugated polymers through structural manipulation has contributed significantly to the advancement of organic electronics. In this work, a redox active conjugated polymer, TPT-TT, composed of alternating 1,4-(2-thienyl)-2,5-dialkoxyphenylene (TPT) and thienothiophene (TT) units is reported with non-covalent intramolecular S⋯O and S⋯H-C interactions that induce controlled main-chain planarity and solid-state order. As confirmed by density functional theory (DFT) calculations, these intramolecular interactions influence the main chain conformation, promoting backbone planarization, while still allowing dihedral rotations at higher kinetic energies (higher temperature), and give rise to temperature-dependent aggregation properties. Thermotropic liquid crystalline (LC) behavior is confirmed by cross-polarized optical microscopy (CPOM) and closely correlated with multiple thermal transitions observed by differential scanning calorimetry (DSC). This LC behavior allows us to develop and utilize a thermal annealing treatment that results in thin films with notable long-range order, as shown by grazing-incidence X-ray diffraction (GIXD). Specifically, we identified a first LC phase, ranging from 218 °C to 107 °C, as a nematic phase featuring preferential face-on π-π stacking and edge-on lamellar stacking exhibiting a large extent of disorder and broad orientation distribution. A second LC phase is observed from 107 °C to 48 °C, as a smectic A phase featuring sharp, highly ordered out-of-plane lamellar stacking features and sharp tilted backbone stacking peaks, while the structure of a third LC phase with a transition at 48 °C remains unclear, but resembles that of the solid state at ambient temperature. Furthermore, the significance of thermal annealing is evident in the ∼3-fold enhancement of the electrical conductivity of ferric tosylate-doped annealed films reaching 55 S cm-1. More importantly, thermally annealed TPT-TT films exhibit both a narrow distribution of charge-carrier mobilities (1.4 ± 0.1) × 10-2 cm2 V-1 s-1 along with a remarkable device yield of 100% in an organic field-effect transistor (OFET) configuration. This molecular design approach to obtain highly ordered conjugated polymers in the solid state affords a deeper understanding of how intramolecular interactions and repeat-unit symmetry impact liquid crystallinity, solution aggregation, solution to solid-state transformation, solid-state morphology, and ultimately device applications.

Effects of Eddies on the Formation and Subduction of North Pacific Subtropical Mode Water Based on Argo Observations

AbstractNorth Pacific subtropical mode water (NPSTMW) is formed in the winter deep mixed layer (ML), due to ocean‐to‐atmosphere interactions, south of the Kuroshio Extension (KE), one of the most energetic eddy activity regions. The large‐scale effects of eddies on the formation and subduction of NPSTMW are investigated on updated Argo observations via kinematic and thermodynamic parameterization approaches. The climatological annual mean eddy‐induced subduction of NPSTMW can reach 4.51 Sv, which accounts for nearly 56% of the total subduction. The local enhancement of the eddy‐induced subduction rate can reach 90 m yr−1 in the high eddy kinetic energy (EKE) zone. Moreover, the spatial distributions of the large eddy‐induced subduction are mostly generated in a zone of steep isopycnals near the KE front area via the parameterization. The diagnosis of the thermodynamic relationship indicates that the eddy‐induced buoyancy flux broadens the area of ocean surface buoyancy loss and then fosters the formation of NPSTMW in winter. The eddy‐induced buoyancy loss due to diapycnal mixing is likely to occur in the relatively steep isopycnals near the KE region, which accounts for 21.2% of the net NPSTMW formation. The contribution of eddy‐induced subduction has the same order as that of lateral induction in each year. The eddy‐induced subduction and lateral induction show similar interannual variations related to the KE variable state.

Orientational anisotropy due to molecular field splitting in sulfur 2p photoemission from CS2 and SF6 - theoretical treatment and application to photoelectron recoil.

Photoelectron recoil strongly modifies the high kinetic energy photoemission spectra from atoms and molecules as well as from surface structures. In most cases studied so far, photoemission from atomic-like inner-shell or core orbitals has been assumed to be isotropic in the molecular frame of reference. However, in the presence of molecular field splitting of p or d orbitals, this assumption is not justified per se. We present a general theoretical treatment, linking the orientational distribution of gas-phase molecules to the electron emission and detection in a certain direction in the laboratory frame. The approach is then applied to the S 2p photoemission from a linear molecule such as CS2 and we investigate, how the predicted orientational anisotropies due to molecular field splitting affect the photoelectron recoil excitations. Lastly, experimental S 2p high-kinetic-energy photoelectron spectra of SF6 and CS2 are analyzed using the modeled recoil lineshapes representing the anisotropy-affected recoil effects.

Preferential Corrosion in Cold Sprayed Cu Induced by Oxide Inclusions

Cold spray (CS) deposition is a solid-state deposition technique that finds applications in additive manufacturing, coating, and repairing damaged components. During the cold spray deposition process, feedstock particles are accelerated by compressed gas and impinged onto the substrate at high velocity. Bonding between particles and the surface being coated is established by the high kinetic energy released during collision rather than by added thermal energy. As the particles remain in the solid state during spraying, oxidation is minimized. Despite the partial removal of the native air-formed oxides by the jetting effect, residual oxide debris often remains along the particle boundaries within the sprayed objects as inclusions [1]. The oxide inclusions have attracted attention concerning their influence on the inter-particle bonding strength in the deposit [2]. However, little is known about whether they affect the material’s corrosion behavior.In this work, we report a preferential corrosion phenomenon observed in a CS Cu-diluted HNO3 system that is caused by the remaining oxide inclusions. A mechanism that integrates Cu-NO3 – catalytic corrosion cycles with confined geometry resulting from the dissolution of the oxide inclusions is proposed. Furthermore, we find that this corrosion phenomenon may be mitigated through microstructure engineering. Annealing the CS Cu at 600 °C consolidated the oxide inclusions with their distribution changed from continuous thin films to isolated spherical particles [3]. The propagation of the preferential corrosion is hence interrupted by the lack of interconnected pathways. Counterintuitively, Cl– can function as an inhibitor for this preferential corrosion. Preferential corrosion did not initiate when 1 mM Cl– was initially present in the solution and slowed down when Cl– was added after the preferential corrosion occurred. Reference [1] S. Yin, X. Wang, W. Li, H. Liao, H. Jie, Deformation behavior of the oxide film on the surface of cold sprayed powder particle, Applied Surface Science, 259 (2012) 294-300.[2] Y. Ichikawa, R. Tokoro, M. Tanno, K. Ogawa, Elucidation of cold-spray deposition mechanism by auger electron spectroscopic evaluation of bonding interface oxide film, Acta Materialia, 164 (2019) 39-49.[3] J. Tam, B. Yu, W. Li, D. Poirier, J.-G. Legoux, J.D. Giallonardo, J. Howe, U. Erb, The effect of annealing on trapped copper oxides in particle-particle interfaces of cold-sprayed Cu coatings, Scripta Materialia, 208 (2022) 114333.

Forensic-medical characteristics of penetrating wounds as manifestations of explosive trauma in the case of decomposed bodies examination

The Russian invasion of Ukraine in 2022 caused a significant spike in the number of deaths from blast injury. The impossibility of evacuating the bodies of dead servicemen or civilians from the battlefield for a long time leads to the fact that forensic experts often have to deal with the examination of bodies in a state of decomposed changes. At the same time, the material and technical support of forensic medical institutions in different parts of Ukraine is heterogeneous: most experts do not have access to laboratory or instrumental research methods and can only rely on macroscopic research data. This article provides an overview of the cases of expert examination of cases of explosive trauma of decomposed bodies using macroscopic, microscopic, chemical and instrumental research, which indicates the high efficiency of their use for the purpose of solving expert questions of various nature. At the same time, the identified morphological characteristics of the damage are not purely specific and indicate the action of a blunt solid object with a limited contact surface, which had high kinetic energy and significant penetrating capacity.

Vehicle-assisted ligature decapitation - an unusual case report.

Suicide by vehicle-assisted strangulation resulting in decapitation is a rare occurrence, characterized by a high kinetic energy mechanism that produces a clean-cut appearance in the decapitation area. Often resembling an incisive wound, this particular finding can mislead local authorities into investigating the case as a homicide. This case report describes an adult male who accelerated his vehicle after tying a nylon rope around his neck and securing it to a metallic structure on the wall. Furthermore, we conducted a brief review of cases published within the last ten years, summarizing the most prevalent findings associated with these incidents. By analyzing previously reported cases alongside our own, we aim to consolidate the prevailing patterns observed in vehicle-assisted strangulation cases. This underscores the paramount importance of thorough scene analysis by the medico-legal team and emphasizes the significance of subsequent necropsy findings in accurately discerning the manner of death.

Short communication: Concentrated impacts by tree canopy drips – hotspots of soil erosion in forests

Abstract. The degradation of ground vegetation cover caused by large grazing herbivores frequently results in enhanced erosion rates in forest ecosystems. Splash erosion can be caused by drop impacts with a high throughfall kinetic energy (TKE) from the tree canopy. Notably larger canopy drips from structurally mediated woody surface points appear to induce even higher TKE and generate concentrated impact locations causing severe focus points of soil erosion. However, TKE at these locations has rarely been reported. This pilot study investigated the intensity of TKE at a concentrated impact location and compared it with general TKE locations under the canopy and freefall kinetic energy (FKE) outside the forest. We measured precipitation, TKE and FKE using splash cups at seven locations under Japanese beech trees and five locations outside the forest during the leafless and leafed seasons in 2021 in a mixed forest with evergreen coniferous trees and deciduous broadleaved trees in Japan. The TKE at the concentrated impact location was 15.2 and 49.7 times higher than that at the general locations under the beech and FKE, respectively. This study confirmed that canopy drip from woody surfaces could be a hotspot of soil erosion in temperate forest ecosystems. Throughfall precipitation at the concentrated impact location was 11.4 and 8.1 times higher than that at general locations and freefall, respectively. TKE per 1 mm precipitation (here, “unit TKE”) at the concentrated impact location (39.2 ± 23.7 J m−2 mm−1) was much higher than that at general locations (22.0 ± 12.7 J m−2 mm−1) and unit FKE (4.5 ± 3.5 J m−2 mm−1). Unit TKE in the leafless season was significantly lower than in the leafed season because of fewer redistribution of canopy drips induced only by woody tissue. Nevertheless, unit TKE at the concentrated impact location in the leafless season (36.4 J m−2 mm−1) was still higher than at general locations in the leafed season. These results show that potentially high rates of sediment detachment can be induced not only by throughfall precipitation but also by larger throughfall drop size distributions at the concentrated impact location, even in the leafless season. Further studies with more replication building on this first report are necessary to investigate how many of these concentrated impact locations may occur on average with different tree species to better assess the extent of the erosion risk under forests.

WIRELESS SENSOR SYNCHRONIZATION METHOD FOR MONITORING SHORT-TERM EVENTS

Topicality. The key part of experimental research is obtaining the most accurate data about the studied object or event. Often, it is necessary to record parameters of processes that are c hallenging to precisely localize in space and time. The process or event under consideration can occur very rapidly, within fractions of a second, making it difficult for the researcher to deploy and configure recording equipment. This necessitates the creation of a network consisting of numerous recording devices to not miss critical events related to the studied process and obtain a sufficient volume of experimental data. Another issue is the synchronization of data obtained from different measurement devices. Spatially distributed recording devices must operate with a high degree of autonomy, leading to discrepancies in timekeeping and the need for synchronization. In processes with sub-millisecond durations, imperfections in timekeeping at each node have a significant impact: undetected and unaccounted discrepancies can lead to distortion or a misunderstanding of the overall picture of the studied process or event, even after acquiring all the necessary data. This is why the development and improvement of methods for synchronizing data recording nodes in distributed wireless sensor networks is important and urgent task. Task statement. One practical application of the proposed solution is the study of injuries caused by the penetration of foreign objects with high kinetic energy into the human body. These studies are conducted using artificial simulators of the human body made from composite materials and ballistic gelatin, with implanted electronic devices for recording changes in physical parameters. Results and conclusions. The article presents a hardware and software method, along with the technical implementation of the process for synchronizing the local clocks of wireless nodes, integrated into a unified information-measurement system located on the simulator. The proposed method allows achieving synchronization accuracy of no more than 12 μs/second using low-cost commercial off-the-shelf components. The practical part of the research discusses microprocessors from the ESP family, which, in general, provide sufficient time synchronization accuracy when using the proposed method, allowing for cost-effective node development within the system. The proposed method can also be applied in other fields, such as measuring vibrations in electrical machines and engines, as well as structural health monitoring.

Experimental investigation of a triple point in a dusty plasma

In this work, we present the first experimental observation of a triple point in a strongly coupled complex plasma medium. Initially, a 2D crystalline structure of the dust component consisting of monodisperse micrometer-sized particles is created. The evolution of this monolayer as a function of the discharge voltage is then investigated and, in the course of this evolution, the co-existence of three distinct phases of the system consisting of a liquid region and two crystalline regions with square and hexagonal lattice configurations is observed. Two different transition sequences are identified in the system, depending on the initial dust density of the monolayer. The particles in the fluid region have high kinetic energy. Before the emergence of a triple state, it is found that the particles in the different lattice geometries show different in-plane or out-of-plane oscillations. It is conjectured that a complex or mixed instability that originates in the system in a localized manner gives rise to the formation of the triple point in our experiments.