Small Values Research Articles

Effect of vacuum heat treatment temperature on anti-corrosion and conductivity properties of C/TiC nanocomposite coated titanium foil for PEMFC bipolar plates

In this work, a C/TiC nanocomposite coating was prepared on titanium foil using a combination of magnetron sputtering and heat treatment technology to improve the corrosion resistance and conductivity of bipolar plates. The effect of heat treatment temperature on surface morphology, chemical composition, mechanical property, hydrophobicity, corrosion resistance and conductivity of coated samples was investigated. The results indicate that the roughness of the coating increase with heat-treated temperature and the corrosion current density (icorr) firstly decreases and then increases in 0.5 M H2SO4 solution containing 5 ppm HF at 80 ℃, reducing its smallest value at 700 ℃ (1.28 μA cm−2), which is declined by 3 orders of magnitude compared to the substrate (562.90 μA cm−2). After potentiostatic polarization experiment (PP) for 12 h, the polarization current density (ipp) of the coatings firstly reduces and then increases, with values of 1.48, 0.70, 0.36, 0.41, 1.32 and 1.35 μA cm−2 corresponding to the substrate and coated samples, respectively. Furthermore, the interface contact resistance (ICR) of coated samples firstly decreases and then increase with temperature rising, which are less than 10 mΩ cm2. After 12 h PP tests, the ICR increase, with values of 18.42, 26.28, 13.64, 10.26 and 11.56 mΩ cm2 corresponding to RT, 600 700 800 and 900 ℃, respectively. The water contact angle of the coated sample for 600 and 700 ℃ are higher than that of other samples and they reached 87.6°and 85.3°, exhibiting a good hydrophobicity.

Advanced dynamic thermal vibration of thick magnetostrictive FGM plates-cylindrical shells in unsteady yawed supersonic flow

The thermal vibration of magnetostrictive functionally graded material (FGM) thick plates-cylindrical shells in advanced dynamic unsteady yawed supersonic flow with nonlinear third-order piston theory is studied by using numerical method. The effects of yawed angle, controlled gain, and third-order shear deformation theory (TSDT) on the thermal stress and center displacement are analyzed. The nonlinear coefficient of TSDT and advanced shear correction provide the main effects on the time response values of displacements and stresses. Also the controlled gain provides the additional effects on the transient response values to control the displacements and stresses into smaller values. The novelties of the present article are the advanced shear coefficient included with TSDT displacement, velocity feedback control law, and nonlinear third-order piston theory used to obtain the thermal vibration modeling equation and the simulation results for FGM plates-shells in nonlinear unsteady yawed supersonic flow. The FGM structures are usually used for high temperature area to provide better resistance in the deflection and stress. The generalized differential quadrature (GDQ) methods used in the numerical calculation for getting the simulation results for FGM plates-shells in nonlinear unsteady yawed supersonic flow.

Distribution and Anisotropy of the Energy Transfer Rate in the Solar Wind Turbulence

The distribution of the energy transfer rate is critical for the interpretation of the intermittent energy cascade in the solar wind turbulence. However, the true observational distribution of the energy transfer rate in the solar wind and its anisotropy remain unknown. Here, we use a 7 day interval measured by Wind in the fast solar wind and investigate the distribution and anisotropy of the energy transfer rate based on the log-Poisson model. We find that the probability density distribution consists of two parts. The majority part locates at smaller values and is consistent with the log-normal distribution. The estimated mean value and standard deviation of the logarithmic energy transfer rate for the majority are both smaller in the direction parallel to the local mean magnetic field than in the perpendicular direction. The mean value displays a power-law shape with respect to the scale, with flatter index in the parallel direction and steeper index in the perpendicular direction. The minority part locates at larger values and expands as the scale decreases, indicating the growing intermittency toward smaller scales. The flatness for parallel logarithmic energy transfer rate is larger than that for perpendicular. And it rises as the scale decreases for all directions, demonstrating the relatively longer tail of the distribution with decreasing scale. Our results provide new insight to help interpret the intermittent energy cascade process in the solar wind turbulence.

Friction Modifier Performance in Twin-Disk Tests Using Disks of the Same Microstructure and Hardness

Friction management in the wheel-rail interface has received great attention from railway engineering in recent years, mainly due to the possibility of reducing wheel and rail wear. The addition of greases, lubricants and friction modifiers on the track has increased in the main railroads of the world. However, studies demonstrating the effect of applying friction modifiers are mainly carried out by manufacturers. To evaluate the action of the friction modifier, laboratory tests are less expensive tools and can give an indication of the benefit of the application. Thus, in this work, dry and wet twin-disk tests were carried out using disks with the same microstructure and hardness, evaluating only the action of the friction modifier. It was noted that the retentivity of the friction modifier had increased with the distance covered in the test. These results would contribute to increase the distance between applicators on the railway track and promoting a lower volume of product per distance traveled. The addition of a friction modifier also reduced the traction coefficient throughout the test, which contributed to lower wear of the disk. The friction modifier induced rolling contact fatigue cracks with greater depth and length due to hydro pressurization action. However, the addition was still beneficial because the wet condition keeping the friction at smaller values, the crack propagation takes longer to occur.

Study on the Hydrodynamics of a Cownose Ray’s Flapping Pectoral Fin Model near the Ground

Cownose rays typically swim close to the ocean floor, and the nearby substrate inevitably influences their swimming performance. In this research, we numerically investigate the propulsive capability of cownose rays swimming near the ground by resolving three-dimensional viscous unsteady Navier–Stokes equations. The ground effect generally has a favorable impact on swimming. The thrust and lift increase as the near-substrate distance decreases. Nevertheless, a body length is the recommended distance from the ground, at which the flapping efficiency and swimming stability obtain a good trade-off. The increase in lift is due to the pressure difference between the dorsal and ventral surfaces of the ray, and the thrust boost is due to the enhanced shear vortex at the fin’s leading edge when swimming near the substrate. Our results indicate that the ground effect is more noticeable when the fin flaps are symmetrical compared to asymmetrical. In asymmetric flapping, the hydrodynamic performance improves at a smaller value than the half-amplitude ratio (HAR). The frequency of flapping also significantly affects swimming performance. We find that a superior flapping frequency, at which maximum efficiency is reached, occurs when flapping close to the substrate, and this superior frequency is consistent with the behavior of our model’s biological counterpart.

Differences in Uniquely Identified Peptides Between ddaPASEF and diaPASEF.

Recent advancements in mass spectrometry-based proteomics have made it possible to conduct comprehensive protein analysis. In particular, the emergence of the data-independent acquisition (DIA) method powered by machine learning has significantly improved protein identification efficiency. However, compared with the conventional data-dependent acquisition (DDA) method, the degree to which peptides are uniquely identified by DIA and DDA has not been thoroughly examined. In this study, we identified over 10,000 proteins using the DDA and DIA methods and analyzed the characteristics of unique peptides identified by each method. Results showed that the number of peptides uniquely identified by DDA and DIA using the same column type was 19% and 32%, respectively, with shorter peptides preferentially detected by the DIA method. In addition, more DIA-specific peptides were identified, especially during the first 10% of elution time, and the overall 1/K0 and m/z shifted toward smaller values than in the DDA method. Furthermore, comparing the phosphorylation and ubiquitination proteome profiles with those of whole-cell lysates by DDA showed that the enrichment of post-translationally modified peptides resulted in wider m/z and 1/K0 ranges. Notably, the ubiquitin peptide-enriched samples displayed lower m/z values than the phospho-proteome. These findings suggest a bias in the types of peptides identified by the acquisition method and the importance of setting appropriate ranges for DIA based on the post-translational modification of peptide characteristics.

Analisis Peramalan Penjualan untuk Perencanaan Produksi pada Lavanda Brownies Karawang

This research was conducted at Lavanda Brownies Karawang which compared the moving average and exponential smoothing forecasting methods. This research aims to find out, calculate, analyze and explain how to use the moving average and exponential smoothing methods in sales forecasting for production planning at Lavanda Brownies Karawang as well as to find out, calculate, analyze and explain what forecasting method is most appropriate to use for Lavanda Brownies Karawang based on calculations of Mean Absolute Devitiation (MAD), Mean Square Error (MSE), and Mean Absolute Percent Error (MAPE). This research uses a quantitative descriptive method, to get a general picture of the company's condition, a literature review related to the research topic is carried out as well as field research through interviews and direct observation. Based on the research results, the exponential smoothing forecasting method based on alpha 0.9 is the best forecasting method for production planning. This method was chosen because it has the smallest MAD, MSE and MAPE accuracy values ​​when compared to other methods, namely with MAD of 489,909, MSE of 506.950 and a MAPE percentage of 14,14%, which percentage has the smallest value and is included in the category Good. A smaller MAPE accuracy value indicates more precise forecasting. Because in forecasting the smaller the accuracy value, the better the forecasting results so that the Lavanda Brownies business can plan optimal steamed brownie production activities in the next period.

Optimizing Arterial Tissue Thickness Measurement Protocols: Digital Vernier Caliper Versus Digital Thickness Gauge.

The aim of this study is to analyze the reproducibility of sample thickness measurements taken by a non-experienced user by comparing a standard digital vernier caliper, with four different protocols, to a specialized thickness gauge. The current study is a methodological study where we examined the thickness of the porcine arterial wall in the thoracic aorta of six pigs. Two adjacent samples of 10 × 10 mm from each aorta were excised longitudinally from the anterior wall, resulting in twelve specimens. Five protocols were employed to measure the thickness of each sample. In four of these protocols, digital vernier calipers (Multicomp PRO MP012475) were utilized, while the fifth protocol utilized a specialized digital thickness gauge (Mitutoyo 547-500S, Mitutoyo Corp., Kawasaki, Japan). We observed a higher average thickness of the samples during the initial measurement compared to the second measurement (1.11 ± 0.16 vs. 0.94 ± 0.17, p = 0.0319) with the first protocol and smaller values than those determined at the last measurement (0.93 ± 0.15 vs. 1.10 ± 0.15, p = 0.0135) for the third protocol. Further, with the digital vernier calipers, we recorded lower values for all four protocols than for the digital thickness gauge determinations. In addition, we computed the ratio of the thicknesses measured during the first, second, and third measurements to analyze how consistent the values were across the three consecutive measurements, with no difference regarding the third, fourth, and control protocols. The digital thickness gauge offers dependable measurements, regardless of the user's expertise in assessing tissue thickness, and demonstrates a substantially higher reproducibility when compared to the digital vernier. We also found that taking an average of the thickness measurements from four specific points on each half of the sides or on each diagonal of each corner yielded consistently reliable results over time when using a standard digital vernier caliper instead of a specialized one.

Image compression scheme based on region of interest recognition

Abstract With the development of networks, many fields now demand higher quality in specific image areas, such as main characters in photos, lesion areas in medical images, and features in remote sensing. At the same time, these fields need to manage data storage and transmission effectively for subsequent analysis and application. In order to meet the demand for image compression in modern society, this paper proposes an image compression scheme based on region of interest (ROI) recognition, dividing images into ROI and non-ROI regions and processing them with lossless and lossy compression, respectively, to improve efficiency and ensure ROI quality. The scheme uses the object detection network YOLOv4 to recognize the ROI of the image, designs an image block difference transformation to transform the image pixels into smaller values, designs a lossless DC encoding for the ROI of the image based on the difference between adjacent pixels, and designs a lossy DC encoding with quantization coding for the non-ROI of the image. Experimental analysis of uncompressed images shows the scheme effectively enhances compression efficiency while maintaining ROI quality, proving its practical value.

Adsorption Energies of X-Doped Fullerene (X = Si, Sn, BN): A First-Principles Study

The interaction of dopamine and Si-, Sn-, and BN-doped fullerenes was studied by using the density functional theory (DFT). Adsorption energies of dopamine–C60, dopamine–C59Si, dopamine–C58Sn, and dopamine–C58BN were -0.03 eV, -1.46 eV, -0.06 eV, and -0.05 eV, respectively. All systems had negative adsorption energies, indicating that dopamine can be adsorbed on fullerene. Furthermore, dopamine–C59Si had the smallest value and was chemisorbed shown by a created covalent bond between Si of fullerene and N of dopamine. Therefore, C59Si has a plausible potential as a drug carrier for dopamine molecules.

Computational Fluid Dynamics (CFD) in Arteriovenous (AV) Graft Implantation Through End-to-Side Anastomosis with Varying Tube Diameters Across Different Vascular Access Locations for Dialysis Treatment.

Background/Objectives: Arteriovenous (AV) graft is a procedure for hemodialysis performed in the arm. Optimizing AV graft design is vital to enhance haemodialytic efficiency in patients with kidney disease. Despite being a standard procedure, making it work optimally is still difficult due to various graft diameters and anastomosis configurations, which have limited studies. This research aims to find the ideal AV graft tube diameter on blood flow and pressure gradients and the ideal body site for AV graft implantation and to study their angles for dialysate flow. Methods: Nine models were designed in Autodesk Fusion 360 with 40°, 50°, and 60° angles each having 2 mm, 5.1 mm, and 14.5 mm diameters, all following specific equations on continuity, momentum (Navier-Stokes Equation)), and the Reynolds Stress Model (RSM). The CFD simulation of these models was performed in ANSYS Fluent with an established parameter of 0.3 m/s inlet velocity and stiff/no-slip graft and artery wall boundary condition. Results: As a result, the design with a diameter of 14.5 mm and a 40° angle was overall the most ideal in terms of minimal wall shear stress and turbulence. Conclusions: Thus the brachiocephalic area or the forearm is calculated to be the most optimal implantation site. Additionally, varying angles do affect dialysate flow, as smaller values cause less stress.

PERBANDINGAN FUZZY TIME SERIES MARKOV CHAIN DAN FUZZY TIME SERIES CHENG

Investing is a hot and fast-growing topic right now. Stock.investing.is one of the most popular investments by the public. The JCI is an index that measures the performance of all stocks listed on the IDX. The closing price of the stock is published daily and can be used by investors as an investment benchmark. The occurrence of stock price fluctuations entails a high risk of loss. Predicting stock prices is one way to avoid this risk. Fuzzy time series is a time series model that can be used to minimize the risk of future occurrences. Time parameter data is not stationary, so this research uses fuzzy time series with Markov chains and Cheng's method to determine the JCI completion dates from January 2018 to June 2022. Calculating the accuracy level of the two method approaches using symmetric Mean Absolute Percentage Error (sMAPE), the sMAPE value obtained in the Fuzzy Time Series Markov Chain method is 2.11% and the Fuzzy Time Series Cheng method is 2.98%. The conclusion is that of the two methods the Markov Chain has a smaller value and can be said to be a better method compared to the Cheng method.

Composition, divergence and variability: A comprehensive analysis of fish trait responses to connectivity

Connectivity, a fundamental concept in ecology, refers to the extent to which different habitats or ecosystems are interconnected through the movement of organisms, nutrients, and energy. Lateral hydrological connectivity (LHC) plays an especially critical role in shaping aquatic community organization in river-floodplain systems. However, a comprehensive understanding of various trait responses to LHC remains elusive. We characterized how attributes of fish community traits, specifically composition, divergence, and temporal variability respond to LHC in the Austrian-Hungarian floodplains of the Danube River using environmental DNA (eDNA) metabarcoding. Trait composition was quantified by community-level weighted means (CWM) as the degree of changes in trait responses along the LHC gradient from isolated oxbows to the main river. Divergence was measured using Rao’s quadratic functional diversity index and a null model approach to calculate standardized effect sizes (SES), with larger SES values indicating greater divergence and smaller values indicating convergence. Temporal variability, representing the degree of instability in community traits over time, was calculated using a functional beta diversity measure for multiple communities. Our findings revealed apparent compositional changes for many trait variables, highlighting the significance of LHC in shaping community functional diversity. Divergence patterns indicated that isolated habitats foster trait convergence presumably due to habitat filtering, whereas more connected areas promote trait divergence due to higher species richness and habitat availability. Temporal variability of traits associated with flow preference exhibited a hump-shaped relationship with LHC, suggesting intermediate connectivity zones are hotspots of ecological dynamism. The study suggests that examining composition, divergence, and temporal variability together provides a more complete understanding of trait responses to connectivity, stressing the importance of maintaining diverse connectivity levels in river-floodplain systems for effective conservation and ecosystem management.

Analisis Kualitas Layanan Aplikasi Prestige Di Kabupaten Gresik Menggunakan Metode ServQual

The Prestige application is an online attendance for Gresik Regency ASN. What is the assessment of the feasibility of the functionality of the Prestige Application, and what factors influence employees dissatisfaction with the Prestige Application. In previous research on attendance applications, only regarding the impact of the application on employee performance. This research tests the application functionality, so that it meets what is required. Researchers as instruments and data collectors provide assessments of the Prestige application, finding problems that result in a decrease in the quality of the Prestige application. The ServQual method or what is called the service quality concept is a method used to test the nature of service quality, and involves 90 questionnaire respondents. In this research, it was found that there is no forget password feature, and importantly there is a feature to display the total number of attendance points. The Reliability dimension gets the largest value, and the Empathy dimension gets the smallest value. As input, BKPSDM needs to add a forget password feature and information regarding total employee attendance points.

Effects of Si/Ge superlattice structure with intermixed interfaces on phonon thermal conductivity

By means of the Monte-Carlo/Molecular Dynamics and the non-equilibrium Molecular Dynamics methods we investigate the cross- and in-plane thermal conductivities of the (001)-, (110)- and (111)-oriented Si/Ge films (2 − 20 nm) and bulk superlattices with an intermixing at interfaces in comparison with the corresponding alloy structures at 300 K. For the first time the anomalous conductivity reduction of the in-plane thermal transport with respect to the film thickness has been revealed. This effect can be caused by interplay of three phonon scattering mechanisms: the phonon-alloy scattering mechanism, which is dominant, and competing phonon-phonon and phonon-surface scatterings due to the phonon depletion and the surface phonon localization, respectively. In general, the estimated minimal in-plane thermal conductivity values are found to be of 1.7 W/(m∙K) for the SiGe alloy thin films. It is established that the cross-plane thermal conductivity in the Si/Ge film superlattices crucially depends on intermixing at interfaces displaying even smaller values (less 1.5 W/(m∙K)) than in the corresponding SiGe alloy structures. We also show Si/SiGe superlattices in comparison with Ge/SiGe ones to provide up to 9 % gain in decreasing of both cross and in-plane thermal conductivities due to specific redistribution of peak weights in phonon density of states, which affect the thermal transport. These results reveal the insights into the application of SiGe-based superlattices and alloys for the cross- and in-plane thermoelectrics from the thermal transport minimization viewpoint.

Nanoscale niobium coatings including superior conducting and corrosion resistance on titanium foil materials for PEMFC bipolar plates

In this work, the nanoscale Nb coating for titanium is fabricated by high power impulse magnetron sputtering technology to enhance its conductivity and corrosion resistance, which is utilized as bipolar plates material. The surface morphology, composition, corrosion resistance and conductivity of specimens with various deposition times were characterized. The results demonstrate that the thickness and roughness of nanoscale coatings increase with deposition time and all the Nb-coated titanium specimens exhibit superior corrosion resistance in 0.5 M H2SO4 solution with 5 ppm HF at 80 °C. The corrosion current density increases and then decreases with deposition time, reaching its smallest value at 600 s (3.07 μA cm−2), which is reduced by 3 orders of magnitude compared to the substrate (387.98 μA cm−2). After potentiostatic polarization experiment (PP) for 12 h, the polarization current density (ipp) of coatings reduces as deposition time increases, with values of 1.54, 0.58, 0.45 and 0.27 μA cm−2, respectively. Furthermore, a low ICR is obtained for fresh Nb-coated titanium specimens, with values of 8.45, 8.95, 3.62 and 3.04 mΩ cm2, respectively. After PP for 12 h, the ICR slightly increase to values of 9.83, 9.63, 6.76 and 6.15 mΩ cm2, which still satisfy the demand of 2025 DOE requirements (≤10 mΩ cm2).

Age-dependent flexion relaxation phenomenon in chronic low back pain patients.

The flexion relaxation phenomenon (FRP) is characterized by suddenly reduced paraspinal muscle activity during full flexion. Previous studies showed significant differences in FRP and flexion angles in chronic low back pain (cLBP) patients compared to individuals without back pain (no-BP). However, the relationship between FRP and flexion angles remains insufficiently understood in older populations. Thus, this study investigated the relationship between FRP and flexion angles concerning to the age and presence of cLBP. Forty no-BP subjects (20m/20f; mean age 41.5years) and thirty-eight cLBP patients (19m/19f; mean age 43.52years) performed maximum full upper body flexion task. Electromyographic (EMG) measurements were conducted to assess the activity of lumbar erector spinae (ESL), thoracic erector spinae (EST), and multifidus (MF). Lumbar, thoracic, and pelvic angles at the onset (OnsetL/T/P) and offset of the FRP (OffsetL/T/P) and maximum trunk inclination (MaxL/T/P) were calculated. The FRP was evaluated using a flexion relaxation ratio (FRR). cLBP patients showed smaller FRR in MF and right ESL compared to no-BP individuals (p < 0.05), while no differences were found in flexion angles between two groups. Subjects over 40 showed smaller FRR in MF and ESL, and smaller flexion angles on OffsetL and MaxL (p < 0.05). Age-related analysis in the cLBP group revealed that patients over 40, compared to younger ones, had smaller FRR in MF and ESL, and smaller values in all thoracic and lumbar flexion angles (p < 0.05). While in no-BP group, significant larger flexion angles in OnsetL and OffsetT (p < 0.05) were observed in participants over 40. Pain-related analysis in the older group revealed that the cLBP patients, compared to no-BP individuals, had smaller FRR in right MF and right ESL, and smaller values in all lumbar and thoracic flexion angles (p < 0.05), while in younger group, there were no significant pain-related differences in FRR, with larger values in all lumbar flexion angles (p < 0.05). Our findings indicate a reduction or absence of FRP in cLBP patients compared to no-BP individuals, with age being a significant factor as those over 40 showed smaller FRP and flexion angles compared to younger individuals.

Non‐Linearity in Mean Annual Peak Flow Scaling With Upstream Basin Area: Insights From Percolation Theory

ABSTRACTUnderstanding how annual peak flow, , relates to upstream basin area, , and their scaling have been one of the challenges in surface hydrology. Although a power‐law scaling relationship (i.e., ) has been widely applied in the literature, it is purely empirical, and due to its empiricism, the interpretation of its exponent, , and its variations from one basin to another is not clear. In the literature, different values of have been reported for various datasets and drainage basins of different areas. Invoking concepts of percolation theory as well as self‐affinity, we derived universal and non‐universal scaling laws to theoretically link to . In the universal scaling, we related the exponent to the fractal dimensionality of percolation, (i.e., ). In the non‐universal scaling, in addition to , the exponent was related to the Hurst exponent, , characterizing the boundaries of the drainage basin (i.e., ). The depends on the dimensionality of the drainage system (e.g., two or three dimensions) and percolation class (e.g., random or invasion percolation). We demonstrated that the theoretical universal and non‐universal bounds were in well agreement with experimental ranges of reported in the literature. More importantly, our theoretical framework revealed that greater values are theoretically expected when basins are more quasi two‐dimensional, while smaller values when basins are mainly quasi three‐dimensional. This is well consistent with the experimental data. We attributed it to the fact that small basins most probably display quasi‐two‐dimensional topography, while large basins quasi‐three‐dimensional topography.

Variations in gust factor with wind direction and height based on the measurements from a coastal tower during three landfalling typhoons

Using high-frequency onshore wind data from four different heights of a coastal tower, the variations in gust factor with turbulence intensity, height and wind speed were studied under typhoon conditions. The gust factor increases with increasing turbulence intensity and, most often, can be described by a linear relationship with the turbulence intensity. The gust factor decreases with height and is relatively small compared with those presented in the national codes and other studies. A value of 2.5 is acceptable for the peak factor, which is close to the recommended value of the national code in China. The gust factor increases with increasing wind speed and is also affected by the wind direction. The gust factor has a value to that of previously published results when the wind flows roughly perpendicular to the shoreline, and has a smaller value when the wind flows roughly parallel to the shoreline. The phenomenon is caused by the confinement of shoreline on the sea wave development. Sea waves tend to propagate normal to the shoreline because of the refraction effect. As a result, a shorter roughness length exists in the parallel direction to the shoreline. It can be further explained by the weakness in the momentum flux exchange between the air and sea based on the wave form drag theory when the wind flows parallel to the shoreline.

VARIABILITY REGULARITIES OF THE CEPHALOMETRICAL PARAMETERS OF THE HUMAN FETAL SKULL

The purpose of the study – to find out the regularities of the age dynamics of cephalometricparameters and critical periods of the development of the skull of human fetuses.Material and methods. 60 preparations of skulls and 63 computer tomograms of theheads of human fetuses aged from 4 to 10 months of intrauterine development werestudied. A complex of morphological research methods was applied, which includedanthropometry, morphometry, three- dimensional reconstruction and statistical analysis.Linear and angular parameters of the skull were measured, and their ratios, characterizingthe constitutional and cephalometric parameters of the individual (cranial and facialindices), were determined. Results. The analysis of absolute cephalometric parameters (longitudinal, transversediameters, skull circumference, height dimensions) demonstrated the predominanceof logarithmic dynamics of their changes in human fetuses, that is explained by theiraccelerated growth during the 4th month of intrauterine development and a slowdownduring the 7th month with subsequent acceleration in the 8th month of prenatal development.A straight trend line is characteristic of the V-S height (distance from the Sella turcica tothe highest point of the skull), which is explained by the accelerated growth of the anteriorand posterior cranial fossae, while the sphenoid bone and the region of anterior fontanelledevelop in a consistent direction and pace. The linear pattern of growth is typical for theforamen magnum, hard palate, length of the orbit, body and ramus of the mandible, aswell as for relative cephalometric parameters that show a wide range of morphometricvariability. Analysis of the scatter diagram using the method of weighted least squaresdistances showed a decrease in the angle of the front part of the cranial base until the5th month of intrauterine development, followed by an increase in the 7th-8th months ofprenatal development. Multivariate regression analysis of the relationship between fetalage, cranial index and the value of the angle of the front part of the cranial base showedpronounced anatomical variability, which depended on the craniotype. Before the end ofintrauterine development, the N-S-Ba angle increases, but at the beginning of the fetal periodof ontogenesis, it decreases. It has the smallest values in dolichocephals compared to othercraniotypes. The largest values of this angle are found in mesocephals at the beginning of thefetal period, and in brachiocephals and mesocephals at the end of intrauterine development.Conclusions. 1. Critical periods of skull development in the fetal period of humanontogenesis are the 4-5th and 7-8th months, during which uneven changes in absoluteand relative craniometric parameters are observed. 2. The value of the angle of the frontpart of the cranial base can be a diagnostic and prognostic indicator in combinationwith the cranial index, which characterize the craniotype of the individual, during themonitoring of the normal development of the skull and brain of the fetus.