Range Of Ratios Research Articles

Energy-efficient high-linearity SAR ADC with a unary–binary hybrid capacitor switching method

This study developed a 10-bit 10 MS/s energy-efficient and high-linearity successive approximation register (SAR) analog-to-digital converter (ADC). The design utilized a capacitor array structure employing “3-bit thermometer code + 6-bit binary code” to achieve 10-bit quantization through a Vcm-based three-level capacitor switching scheme. The thermometer codes optimized the switching capacitors of the most significant bits to enhance linearity. Further, a unary and binary code control method was implemented to automatically switch across the remaining unary code capacitors when the differential output of the digital-to-analog converter was below 64 least significant bits (LSB). This method reduces the switching energy by 30% compared to the binary CDAC, while RMSDNL and RMSINL are reduced by 47.50% and 26.08%, respectively. The 10-bit SAR ADC was designed with 0.18μm CMOS technology, and the ADC core occupied an area of 0.077 mm2. At supply and reference voltages of 1.2 V, the ADC achieved differential non-linearity and integral non-linearity values of +0.36/−0.32 and +0.4/−0.37 LSB, respectively, at a sampling frequency of 10 MS/s and with a 1% capacitor mismatch. At an input signal frequency of 4.65 MHz, the ADC achieved a signal-to-noise-and-distortion ratio (SNDR) and spurious-free dynamic range (SFDR) of 60.07 and 80.03 dB, respectively. The ADC consumed a power of 137.36 μW, and the Walden figure of merit was 16.74 fJ/conversion-step.

Multistage microfluidic assisted Co-Delivery platform for dual-agent facile sequential encapsulation.

The integration of multiple therapeutic agents within a single nano-drug carrier holds promise for advancing anti-tumor therapies, despite challenges posed by their diverse physicochemical properties. This study introduces a novel multi-stage microfluidic co-encapsulation platform designed to address these challenges. By carefully orchestrating the nano-precipitation process sequence, this platform achieves sequential encapsulation of two drugs with markedly different physicochemical characteristics. Using the multi-stage microfluidic TrH chip, hybrid nanoparticles (HNPs) loaded with paclitaxel (PTX)-simvastatin (SV), PTX-lenvatinib (LV), and SV-LV were synthesized. Unlike conventional Bulk methods and existing commercial microfluidic Tesla and Baffle chips, the HNPs produced here exhibit a core-shell structure and uniform particle size distribution, crucial for enhancing drug delivery efficacy. Notably, this method achieves nearly 100 % encapsulation efficiency for both drugs across a dual-drug feed ratio range from 1:4 to 4:1. Drug loading efficiencies were quantified for PTX-SV/HNPs (14.97 ± 1.19 %), PTX-LV/HNPs (16.58 ± 0.69 %), and SV-LV/HNPs (19.21 ± 2.38 %). PTX-SV/HNPs demonstrated sequential release characteristics of SV and PTX, as confirmed by in vitro drug release experiments. Significantly, PTX-SV/HNPs exhibited superior cytotoxicity against HepG2 cells compared to individual PTX and SV treatments, underscoring their potential in cancer therapy. In conclusion, the developed multi-stage microfluidic platform represents a robust strategy for co-encapsulating drugs with substantial physicochemical disparities, thereby offering a promising avenue for advancing multi-drug delivery in nanomedicine applications.

Enhancing transcranial ultrasound stimulation planning with MRI-derived skull masks: a comparative analysis with CT-based processing

Objective.Transcranial ultrasound stimulation (TUS) presents challenges in ultrasound wave transmission through the skull, affecting study outcomes due to aberration and attenuation. While planning strategies incorporating 3D computed tomography (CT) scans help mitigate these issues, they expose participants to radiation, which can raise ethical concerns. A solution involves generating skull masks from participants' anatomical magnetic resonance imaging (MRI). This study aims to compare ultrasound field predictions between CT-derived and MRI-derived skull masks in TUS planning.Approach.Five participants with a range of skull density ratios (SDRs: 0.31, 0.42, 0.55, 0.67, and 0.79) were selected, each having both CT and T1/T2-weighted MRI scans. Ultrasound simulations were performed using BabelBrain software with a single-element transducer (diameter = 50 mm,F# = 1) at 250, 500, and 750 kHz frequencies. CT scans were used to generate maps of the skull's acoustic properties. The MRI scans were processed using the Charm segmentation tool from the SimNIBS tool suite using default and custom settings adapted for better skull segmentation. Ultrasound was adjusted to target 30 mm below the skull's surface at 54 electroencephalogram (EEG) locations.Main Results.The custom setting in Charm significantly improved the Dice coefficient between MRI- and CT-derived masks when compared to the default setting (p< 0.001). The maximum pressure error significantly decreased in the custom setting compared to the default setting (p< 0.001). Additionally, the focus location error median across different SDRs averaged 2.32, 1.45, and 1.57 mm in default and 2.08, 1.38, and 1.44 mm in custom conditions for 250 kHz, 500 kHz, and 750 kHz respectively.Significance.MRI-derived skull masks offer satisfactory accuracy at many EEG sites, and using custom settings can further enhance this accuracy. However, significant errors at specific locations highlight the importance of carefully considering stimulation location when choosing between CT- and MRI-derived skull modeling.

The mediating role of body surface area-adjusted basal metabolic rate: effects of low muscle mass and central obesity on cognitive impairment in Chinese patients with type 2 diabetes mellitus

BackgroundThis study investigates the relationship between basal metabolic rate (BMR), body composition, obesity indices, and cognitive impairment (CI) in middle-aged and older type 2 diabetes mellitus (T2DM) patients, assessing their potential role in CI screening.MethodsA cross-sectional study included 1243 T2DM patients over 45 years old. CI was assessed using the Montreal Cognitive Assessment. BMR and body composition indices were measured through bioelectrical impedance analysis. The associations and predictions related to CI were explored using multivariable-adjusted logistic regression, restricted cubic spline (RCS) models, and receiver operating characteristic (ROC) curve analyses. Mediation analysis explored the role of BMR adjusted by body surface area (BMR/BSA) in CI risk.ResultsPatients with CI showed significantly lower BMR, BMR adjusted for height squared (BMR/Height²), BMR/BSA, appendicular skeletal muscle mass (ASM), and fat-free mass (FFM), alongside higher waist circumference (WC) and percentage of body fat. Logistic regression showed that participants in the fourth quartile of BMR, BMR/Height2, and BMR/BSA had approximately a 54% reduced risk of CI (odds ratio range 0.457 to 0.463). RCS analysis indicated a linear decrease in CI risk with increasing BMR metrics. ROC analysis indicated high predictive efficacy for CI with combined indicators, particularly BMR and FFM (area under the curve 0.645). Mediation analysis suggested that BMR/BSA played a significant mediating role in WC, ASM and FFM on CI risk, with a mediation proportion ranging from 45.73% to 50.87%.ConclusionLow energy expenditure assessed by BMR/BSA is an independent risk factor for increased CI risk in middle-aged and elderly T2DM patients. Central obesity, low muscle mass, and low energy expenditure significantly elevate CI risk in this population.

Oxidative oligomerization of a synthetic fraction of hydrocarbons from the Fischer-Tropsch synthesis

The work investigated the process of oxidative oligomerization of Fischer-Tropsch synthesis products - a fraction of C10-C15 hydrocarbons with a total content of alkenes (mainly β- and γ-alkenes) of 64.7 wt. % using zirconium octoate as a catalyst. The hydrocarbon fraction was obtained on a zeolite-containing catalyst at a pressure of 2.0 MPa, a temperature of 250 °C, H2/CO ratio at the reactor inlet of 1.70, a gas space velocity of 1000 h-1 and circulation mode ratio range 0-16. It was found that at a temperature of 160 °C the catalyst content is 5.0 wt. %, process duration 6 hours and pressure (air) - 2.5 MPa, target fraction yield - 52.7 %. It was found that the oligomerization product has a low pour point of minus 31 °C. It was proposed to improve the viscosity characteristics of the oligomerization product by introducing additives into its composition, for example, polymethacrylates or polyisobutylene.

Relationship Between Thermodynamic Modeling and Experimental Process for Optimization Ferro-Nickel Smelting

Saprolite ores in nickel laterite deposits are pyrometallurgically processed to produce Fe-Ni alloy and Ni matte. The key to achieving the highest recovery degrees from nickel ore in electric arc furnaces and producing top-quality ferro-nickel alloys lies in maintaining optimal carbon consumption and carefully controlling the composition of the slag. This research work focused on finding the optimal smelting procedure for extracting ferro-nickel from calcined nickel ore. Comparing experimental data to the results of thermodynamic modeling using Factsage 8.2 software was a key part of the study. The nickel smelting process, which involved a carbon consumption of 4 wt.%, resulted in ferro-nickel with an Fe/Ni ratio of 4.89 and slag with a nickel content of just 0.017%. The structure and properties of nickel slag in the MgO-SiO2-FeO system were investigated by observing the changes in the MgO/SiO2 ratio. This study found a significant nickel recovery degree of 95.6% within the optimal M/S ratio range of 0.65 to 0.7. When the M/S ratio exceeds 0.7, iron-rich magnesium silicates (MgxFeySiO2+n) are generated within the slag. These compounds are released downwards due to their higher specific weight, restricting the movement of small metal particles and contributing to increased metal loss through the slag. Optimized slags could revolutionize smelting, increasing metal recovery while minimizing environmental impact.

Exploring the utility of different bulking agents for speeding up the composting process of household kitchen waste

Household kitchen waste (HKW) is produced in large quantity and its management is difficult due to high moisture content and complex organic matter. Aerobic composting of HKW is an easy, efficient, cost-effective and eco-friendly method. This study is designed to achieve a zero-waste concept and to convert HKW. We optimized the type and size of three different bulking agents to speed up the composting process. The tested bulking agents were fallen leaves, sawdust and fly ash. The results showed a higher and longer thermophilic phase (55oC) for 11 days in C2. Higher moisture content (69%) and higher organic matter degradation (38.4%) were also observed in C2. The pH range in all compost treatments was 7-8.5, Electrical conductivity range was 1.8–3.55 mS/cm, C/N ratio range was 15.4–18.1, water holding capacity range was 3.25–4.3 g water/g dry sample, total potassium range was 1.52–1.61%, total phosphorous range was 0.83–1.14%. The highest germination index (119.1%) was also obtained in C2. The highest chili height (16.7 cm), greater number of leaves (20), greater shoot fresh weight (4.75 g) and root fresh weight (1.2 g) was obtained in the presence of C2. Similarly, greater water WHC (2.8 g water/g DW), higher porosity (55.49%) and higher aggregate stability (54.14%) of soil was also obtained by C2. This research effectively reduced the maturation time to 32 days and converted kitchen waste into compost (resource). This is a very practical idea for home composting and kitchen gardening to combat food security issues in developing countries.

Review of Impact of Risk Reduction Sessions on Sexual Behaviors in HIV Prevention Trials: Insights from Africa.

Over the past two decades, numerous HIV prevention trials have targeted thousands of young African women, aiming not only to reduce transmissions through biomedical interventions but also to promote safe sexual practices through intensive risk reduction sessions. The primary objective of this study was to review the impact of risk reduction sessions in HIV prevention trials conducted in Africa. We assessed changes in sexual behaviors among women enrolled in various biomedical intervention trials across the African region using both visual and quantitative evaluations. Meta-analysis techniques were used to estimate overall odds ratios. In a sub-group analysis, we also used semiparametric regression models to capture important features of the associations between sexual behaviors across the study visits with minimal statistical assumptions. Key time points were identified using the "zero-crossing" technique. Overall summary odds ratio (OR) for condom use in last sex was estimated as 2.21 (95% CI 2.06, 2.36). In our sub-group analysis, women who reported multiple sexual partners declined (adjusted odds ratios (aORs) range: 0.61-0.67) while condom use in last sex improved over time (aORs ranged from 2.22-to-2.60); 347(57%) women HIV seroconverted within the first 6-months which was the most crucial time point with substantial reductions in risky behaviors. This review highlights that the gradual cumulative effect of risk reduction sessions, rather than an immediate substantial impact, may have significant implications in clinical research settings. Effective and sustainable risk reduction programs should include biological components such as pre-exposure prophylaxis (PrEP) to reduce HIV transmission.

The effect of blade turning angle on rotation improvement of a small horizontal axis wind turbine

Optimization of wind turbine aerodynamic performances implies solving the problem in the domains such as airfoil selection, blade rotation angle, chord optimization, number of blades, appropriate tip speed ratio, etc. The current paper studies the effect of blade rotation angle [Formula: see text] on power coefficient [Formula: see text], torque [Formula: see text] and mechanical power [Formula: see text] in a small horizontal axis wind turbine ( HAWT). The analysis involves two models of blades ( V and) of the airfoil class SD 7003. The first part of the paper employs numerical analysis, that is, Ansys CFX and Ansys Fluent software packages, to define wind turbine characteristics. The obtained results indicate that as the rotation angle [Formula: see text] increases the [Formula: see text] increases within an appropriate range of tip speed ratio [Formula: see text] change. The second part describes experimental investigation conducted on considered HAWT to define the values of [Formula: see text] and [Formula: see text] for studied blade rotation angles and comparison with the values obtained from Ansys. Existing differences in values are a consequence of the design of the HAWT, that is, the influence of the mass moment of inertia of the rotor and generator as well as the placement of the generator. Experimental setup and methodology allow for investigating the effect of different blade models, rotor and generator structure on wind turbine torque and mechanical power output characteristic.

Advanced design strategies and applications for enhanced higher-order multisegment denatured pascal curve gears

The existing Pascal curve gears suffer from limited flexibility in pitch curves and restricted changes in transmission ratios. This has impeded the application in a range of mechanical systems that require more adaptable gear solutions. For this, a design procedure for higher-order multisegment denatured Pascal curve gear is proposed. This innovative design offers greater flexibility in pitch curves and allows for a broader range of transmission ratios. The analysis of the transmission ratio confirms the theoretical predictions and highlights the effectiveness of the proposed gear design in achieving variable transmission ratios. The transmission mechanism of the higher-order multisegment denatured Pascal curve gear is analyzed and the unified mathematical expression of the families of Pascal curve gear is derived. The non-circular gears with free-form pitch curves can be obtained from higher-order multi-segment denatured Pascal curves by adjusting design parameters to unify different types of pitch curves. This approach provides significant flexibility in achieving specific transmission characteristics. Then the transmission characteristics are discussed. To further validate the design, the visual analysis and design software of the higher-order multisegment denatured Pascal curve gear is compiled based on Visual Basic, and is verified with the example. The novelty Pascal curve gears is applied to drive the differential velocity vane pump. The displacement, instantaneous flow rate, and pulsation rate of the differential velocity vane pump are calculated. The novelty drive mechanism could meet the requirements and have good performance. The application shows that the higher-order multisegment denatured Pascal curve gear is feasible in practice.

Impacts of seasonality on mercury concentrations, polyunsaturated fatty acids, and stable isotopes: implications for the use of tetragnathid spiders as sentinels.

Riparian spiders are used in ecotoxicology as sentinels of bioavailable contaminants that are transferred from aquatic to terrestrial habitats via emergent aquatic insects. Spiders in the family Tetragnathidae are particularly of interest because a high proportion of their diet consists of emergent aquatic insects and their contaminant loads reflect the amount transferred through the food web to riparian predators. The transfer of contaminants can be determined through food web tracers such as stable isotopes and polyunsaturated fatty acids; however, it is unclear how contaminants and tracers vary over the course of a year. The objective of this study was to determine whether seasonality affected size, carbon and nitrogen stable isotopes, polyunsaturated fatty acid biomarkers, mercury, and other trace metal concentrations in tetragnathid spiders. Spiders were sampled fortnightly from a single site on the Stones River in Tennessee, USA, for an entire active season (April through October). Spider mass and length steadily increased from April to September to a maximum average value of 0.078 ± 0.03 g, then decreased in October. Seasonal trends were observed for carbon and nitrogen stable isotopes, with significantly decreased signatures occurring late in the active season. Overall, methyl mercury concentrations (range: 12.1-134.4 ng/g) and the methyl-total mercury ratio (range: 49%-98%) increased throughout the active season, with higher variability observed at the end of the active season. Collectively, our results indicate that seasonality affected several important endpoints and that spiders collected during the end of the active season may not be representative of spiders during the entire active season.

C/O ratios in self-gravitating protoplanetary discs with dust evolution

Abstract Elemental abundances, particularly the C/O ratio, are seen as a way to connect the composition of planetary atmospheres with planet formation scenario and the disc chemical environment. We model the chemical composition of gas and ices in a self-gravitating disc on timescales of 0.5 Myr since its formation to study the evolution of C/O ratio due to dust dynamics and growth and phase transitions of the volatile species. We use the thin-disc hydrodynamic code FEOSAD, which includes disc self-gravity, thermal balance, dust evolution, and turbulent diffusion, and treats dust as a dynamically different and evolving component interacting with the gas. It also describes freeze-out, sublimation, and advection of four most abundant volatile species: H $_2$ O, CO $_2$ , CH $_4$ , and CO. We demonstrate the effect of gas and dust substructures such as spirals and rings on the distribution of volatiles and C/O ratios, including the formation of multiple snowlines of one species, and point out the anticorrelation between dust-to-gas ratio and total C/O ratio emerging due to the contribution of oxygen-rich ice mantles. We identify time and spatial locations where two distinct trigger mechanisms for planet formation are operating and differentiate them by C/O ratio range: wide range of the C/O ratios of $0-1.4$ for streaming instability, and a much narrower range $0.3-0.6$ for gravitational instability (with the initial value of 0.34). This conclusion is corroborated by observations, showing that transiting exoplanets, which possibly experienced migration through a variety of disc conditions, have significantly larger spread of C/O in comparison with directly imaged exoplanets likely formed in gravitationally unstable outer disk regions. We show that the ice-phase $\textrm{C/O}\approx$ 0.2–0.3 between the CO, CO $_2$ , and CH $_4$ snowlines corresponds to the composition of the Solar system comets, that represent primordial planetesimals.

Mechanical response characteristics and cushioning of sealed airbags under different length–diameter ratios

In the event of a mine fire, rapidly constructing blast-resistant seals is one of the most effective measures to contain the disaster. This study conducted blast cushioning experiments on sealed airbags and numerical simulations by analysis system/Livermore software-dynamics (ANSYS/LS-DYNA), an explicit simulation software, to analyze the mechanical response characteristics and cushioning effectiveness of sealed airbags under different length-to-diameter ratios. The research results indicate that airbags with different length-to-diameter ratios all exhibit cushioning effects, and the airbag can recover its deformation after pressure release. As airbag length increases, vertical deformation along the pipeline appears, forming a radial compression failure mode. Stress concentrations are mostly located at the edges of the airbag, while arched structures can reduce the concentrated stress. Excessively long or short airbags significantly increase localized stress concentrations. The total energy absorbed by the airbag during cushioning shows a linear relationship with its length, and an energy absorption model for single-chamber airbags with varying length-to-diameter ratios was established. Under full-scale simulation conditions, the optimal length-to-diameter ratio range is 0.75:1. The reflected energy of shockwave encountering airbag is independent of airbag length and remains a fixed value when inflation pressure remains constant. These findings provide theoretical support for the design and application of explosion-resistant airbag.

Target an arbitrary probability of response using weighted staircase procedures.

Threshold estimation procedures are widely used to measure the stimulus level corresponding to a specified probability of response. The weighted up-and-down procedure, familiar to many due to its use in standard pure-tone audiometry, allows the experimenter to target any probability of response by using different ascending and descending step sizes. Unfortunately, thresholds have a signed mean error that made using weighted staircases inadvisable. The current study evaluated a correction to eliminate the error. Monte Carlo simulations of weighted staircases were used to test the effectiveness of the proposed correction for yes-no and forced-choice tasks with Gaussian and log-Weibull psychometric functions. Results showed that the proposed correction was effective over a wide range of step size magnitudes and ratios with a symmetric psychometric function and less effective when there was asymmetry due to the shape of the function or a high guess or lapse rate. The proposed correction facilitates the use of weighted staircases to target an arbitrary probability of response.

Vortex-induced vibration and energy harvesting in tandem three cylinders with different spacing ratios

The application of vortex-induced vibration, characterized by low flow velocity requirements and low costs, has emerged as a prominent focus of research within the domain of ocean-current energy generation. Currently, researchers have primarily conducted detailed investigations into the vortex-induced vibration characteristics of cylinders, with comparatively less attention given to their energy conversion properties. Consequently, this study employs numerical simulations to examine the energy conversion characteristics of a series arrangement of three cylinders, elucidating the vortex-induced vibration response. The findings indicate that the series arrangement of three cylinders can broaden the velocity range for energy harvesting, thereby enabling the cylinders to sustain high-energy conversion efficiency across a wider velocity spectrum. Furthermore, the energy harvesting capacity of the cylinders is predominantly associated with the amplitude and frequency of vortex-induced vibrations. The total energy harvesting power of the three cylinders in series increased with an increase in the reduced velocity, and the maximum power of the three cylinders can reach 5.211 W. In contrast, smaller spacing ratios may affect the energy harvesting efficiency of the vibration. The total energy harvesting capacity of the three cylinders is stabilized at a certain spacing ratio and velocity range; notably, the energy harvesting output of the upstream cylinder closely resembles that of a solitary cylinder. However, at a higher reduced velocity, the energy harvesting power of the midstream cylinder and the downstream cylinder is significantly greater than that of the upstream cylinder.

Physics Parameter Identification of Annular Tuned Liquid Damper for the Structure‐Damper‐Coupled System Using a Mechanics‐Enhanced SSI Method

Tuned liquid damper (TLD) is one of the main technologies for passive control. The fundamental modal parameters of a TLD contain natural frequency and damping ratio, which are primarily related to the liquid height in the TLD device. Although the liquid height of the TLD is calibrated before installation, it is still necessary to identify the physics parameters of the TLD and the main structure during the service period to prevent the detuning of the TLD. A physics parameter identification method for the structure‐damper‐coupled system based on mechanics‐enhanced stochastic subspace identification (SSI) is proposed in this paper, illustrated through annular TLD (ATLD). By extracting the state matrix of the first controlled mode of the main structure, the natural frequency and damping ratio of the ATLD are identified, thereby determining the liquid height of the ATLD. Numerical models of structure‐ATLD‐coupled systems with different degrees of freedom are constructed, and their simulated acceleration responses under different excitations are obtained. Sensitivity analysis of environmental noise is performed to verify the accuracy and robustness of the proposed parameter identification method. A dynamic test was designed for a steel chimney model to further verify the practicality of this method. The results show that when the noise level of the measurement noise is below 5.0%, the average relative error in identifying the ATLD liquid height does not exceed 10%. The identification error in the damping ratio of the structure‐ATLD‐coupled system will lead to a decrease in the accuracy of ATLD liquid height estimation. The proposed method can effectively identify changes in the ATLD liquid height within the optimal frequency ratio range by analyzing the experimental data from the chimney model. The proposed method can effectively estimate the modal parameters of the coupled system, providing reliable data support for evaluating the working condition of the ATLD during its service period.

Design of a three-speed automatic transmission system with reverse for all-terrain vehicles (ATV)

This work proposes the design and simulation of a conventional three-speed automatic transmission, including reverse gear, for an all-terrain utility vehicle (ATV). The proposed design was generated considering the power requirements needed for the selected vehicle to operate on a specific driving cycle over uneven terrain with variable slopes ranging from -0.5° to 2.5°. A vehicle with well-defined mass, dimensions, and engine displacement was selected as the design criteria. Using the numerical software MATLAB, the power requirements were calculated, establishing that the transmission ratios range from 0.18 to 1. Using commercial Multibody Dynamics (MBD) software, ADAMS, the reliability of the proper functioning of the gear trains was determined based on boundary conditions. Similarly, to verify that the selected materials and components can withstand critical loads, structural static simulations were carried out using the finite element method with the commercial software ANSYS.

SCRAMJET: Future High Speed Aircraft

In the current era of technological advancement, the scramjet has become one of the most conventional engines for achieving supersonic speeds in aircraft. The scramjet comprises three basic components: the inlet, combustor, and nozzle. Various fuels, such as Kerosene, JP-7, JP-8, hydrocarbon-based fuels, and hydrogen, have been used in scramjets, demonstrating distinct performance characteristics. Tests have shown that hydrocarbon-fueled scramjet engines can achieve a Mach number range of 3.5 to 7, while solid-fueled scramjets have the potential to achieve combustion efficiencies of 0.7–0.9. Fuel injection and mixing techniques were applied in the combustor to enhance thrust and pressure ratios. Advanced injection methods were incorporated into the strut or walls of the combustor to improve combustion efficiency. The air intake capability of the scramjet depends on the inlet design, which should aim to minimize spillage drag and ensure adequate shock train formation. The flamelet approach has demonstrated improved combustion performance and maximized fuel efficiency through the effective placement of the flamelet. Additionally, the flamelet approach optimizes fuel mixing and injection processes within the supersonic flow. By employing a dual-mode scramjet isolator, an equivalence ratio range of 0.06–0.32 was achieved during the transition from supersonic to subsonic combustion. Combustion analysis revealed the behavior of the combustor when using jet fuels and additives. CFD data indicated that incomplete combustion releases harmful gases, such as carbon monoxide and nitrogen oxides, while complete combustion produces stable by-products like water and carbon dioxide. These issues are often attributed to inadequate air-fuel mixing or insufficient air supply. Simulations highlighted the need for improvements in combustor design to prevent thermal choking under specific conditions.

ANALYSIS OF RELATED PHYSICAL AND MECHANICAL PROCESSES AND STATES AND SYNTHESIS METHODS OF DESIGN AND TECHNOLOGICAL SOLUTIONS OF ARMORED COMBAT VEHICLES ELEMENTS

Existing research methods of contact interaction and stress-strain state of complex structural elements are analyzed. The main elements of hydraulic transmissions in tank transmissions are ball pistons that are connected to the toroidal running surface of the stator ring. Important parameters of these elements are the ratio of the radii of the piston and the cross-section of the running track. The studied regularities indicate the optimal range of radii ratios, which ensures minimum contact pressure and stress. Taking into account the elastic-plastic deformation of the materials of the contacting parts, in particular the surface layers, is important for recommendatory decisions. Patterns of influence on the characteristics of strength and performance of the investigated structures of varied parameters have been revealed. Accordingly, in each specific case, it is possible to develop recommendations for the justification of progressive technical solutions of certain structures according to the mentioned criteria. Ball pistons in connection with the toroidal running surface of the stator ring are decisive for strength and durability of the hydraulic transmission elements of promising tank transmissions. In particular, important parameters are the radii ratio of the piston, on the one hand, and on the other, of the cross section of the treadmill. Despite the traditionally existing approaches and efforts to bring the shapes of the contacting surfaces of conjugated bodies as close as possible, the work established regularities that contradict such solutions.

Urinary protein-to-creatinine ratio in guinea pigs (Cavia porcellus): Reference range and the effect of age and sex.

There are currently few reports on the normal urinary protein-to-creatinine (UPC) ratio of guinea pigs,and there is little information on the effects of age and sex on this parameter. Urinary protein and creatinine concentrations were measured in a total of 161 clinically healthy guinea pigs, and the UPC ratio was subsequently calculated. The effect of age and sex on these parameters was assessed using Mann-Whitney U tests. Using these data, UPC ratio reference ranges were established. Guinea pig pups younger than 6 months had a significantly higher UPC ratio than adult animals (median UPCs of 1.48 and 0.56, respectively). There was no effect of sex on this parameter. The reference range for the UPC ratio in adult guinea pigs was set at 0.12-2.21. For guinea pigs younger than 6 months, the reference range for the UPC ratio was set at 0.4-3.1. This study was limited by the lack of blood analysis, which could reveal a subclinical health problem that could affect renal function and the extent of proteinuria. In guinea pigs, the UPC ratio is influenced by age but not by sex. Therefore, the reference range established for adult guinea pigs cannot be used for pups younger than 6 months.