Middle Position Research Articles

Study evaluating the curling property of weft knitted fabrics based on pixel analysis

Curling is a common phenomenon observed in knitted fabrics. Curling poses many problems for fabric and clothing production, especially for digital devices, where it can affect the production quality and efficiency, while there is still no accurate method for evaluating it. This study established an evaluation method for the curling properties of knitted fabrics based on pixel statistics. Weft knitted fabric samples were created using a fabric cutter and a piece of paper was placed underneath the fabric. The fabric sample curls, whereas the paper represents a non-curling state. Subsequently, a scanner was used to scan the projections of the circular samples and paper to obtain digital images. The pixel amounts of the curled fabric and paper digital images were measured using the Photoshop 2020 software. The ratio between the fabric and paper projection pixels can be calculated by subtracting from 100% and converting the curling area ratio to the curling distance ratio. This can be used to represent the curling properties of knitted fabrics. The error between the theoretical and measured values is <0.1%, indicating a high level of accuracy. Ten knitted fabrics were validated for analysis. The sample with the maximum deviation between the left, middle, and right positions was 5.9%, whereas that with the minimum deviation was 0.3%. Subsequently, the fabrics were retested on the 7th and 14th days to assess reproducibility. The maximum deviation for each fabric on the 1st, 7th, and 14th days was 4.1%, and the minimum deviation was 0%. Therefore, it can be concluded that the method described in this study can accurately quantify the curling properties of knitted fabrics.

Evaluating the impacts of area closure on soil properties in south central highland of Ethiopia

Soil degradation affects its quality and productivity of the land. To control soil degradation, various soil and water conservation (SWC) measures, including area closure are implemented. Understanding the impacts of SWC measures could support planning and implementation of land management practices. This study aimed to investigate impacts of area closure on soil properties in south central highland of Ethiopia. To acquire the necessary data, we conducted interviews with 80 households. Furthermore, nine years old area closure with physical soil and water conservation (AC-SWC), open grazing with physical SWC (OG-SWC), and open grazing without physical SWC (OG) were identified and each divided into upper, middle, and lower slope positions. In each slope position, 3 sample plots were established at 25–50 m intervals. A total of 27 composite samples and other 27 core samples for bulk density (3 treatments∗3 slope position∗3 replications) were collected and analyzed for soil properties. The data were analyzed using descriptive statistics and one-way ANOVA. The results showed that about 98 % of the respondents perceived that area closure would be an effective way to restore degraded land. Majority of the farmers (86 %) believed that area closure could reduce soil erosion and replenish soil fertility and thus, is beneficial in improving land productivity. Soil test results revealed that AC-SWC had significantly greater (P < 0.05) clay fractions, pH, available potassium, and available phosphorus than OG-SWC and OG. Variations of soil organic carbon (SOC) and total nitrogen (TN) were more pronounced. The SOC in AC-SWC was 83 % and 314 % greater than OG-SWC and OG, respectively. In the AC-SWC, TN was three and seven times higher than that of OG-SWC and OG, respectively. This could be due to vegetation restoration that reduces erosion, and enhances organic matter, moisture, and nutrient. The SOC, TN, pH, available potassium, and clay were significantly greater (P < 0.05) at lower slope position than upper in all forms of land management, which could be due to deposition at downslope. About 12 % and 11 % variations of clay fractions and SOC were, respectively, observed in between upper and lower slope positions at AC-SWC, but they varied by 25 % and 57 %, respectively, in OG. These imply area closure has had a beneficial effect on soil properties even on sloping land. AC-SWC is an important option to integrate in land management for rehabilitation of degraded soil.

Simulation analysis and experimental research on static performance of water-hydraulic pressure difference control valve

Many hydraulic tools, like hydraulic cylinders and hydraulic artificial muscle joints are operated by adjusting pressure differences between different zones. Typically, the method employed to change the pressure difference is establishing hydraulic bridges and adjusting liquid resistance. While effective, this method's drawback is complex structures. To address this issue, a water-hydraulic pressure difference control valve, integrating two hydraulic bridges, was designed. The static performances including the output pressure difference, the flow rate and the force acting on the valve core were analyzed using AMESim and computational fluid dynamics simulations. Based on the simulation results, a prototype of voice coil motor direct drive pressure difference control valve was manufactured and the corresponding experiments were carried out. The computational fluid dynamics simulation results show that the internal leakage and the through-flow capacity difference between throttling grooves affect the flow field characteristics of the valve. When the pump pressure is 3 MPa and the valve opening is at the middle position, the internal leakage increases the flow rate from 2.25 L/min to 2.38 L/min, and the through-flow capacity difference reduces the control port pressure from the theoretical analysis of 1.5 MPa–1.41 MPa. Furthermore, combined with the analysis of the external liquid resistance, the AMESim model of the pressure difference control valve is modified. When the pump pressure is 3 MPa, the pressure difference and flow rate average deviations between the modified AMESim model and the experiment are 0.021 MPa and 0.048 L/min. Finally, a rotational angle experiment for a water hydraulic artificial muscle joints showed satisfactory control effects, suggesting the valve's application in controlling hydraulic tools and actuators.

Numerical simulation of fluid flow characteristics and ultrasonic cavitation performance in novel-designed stirred tank sonoreactor

A novel-designed stirred tank sonoreactor was developed to well solve large-scale dispersion of nanoparticles in liquid phase system. The fluid flow characteristics and ultrasonic cavitation performance in the sonoreactor were numerically simulated by CFD method. By comparing the pressure, cavitation bubble and velocity distribution under different situations, it is found that larger ultrasonic amplitude, relatively smaller ultrasonic frequency, higher saturated vapor pressure and lower viscosity of liquid medium are beneficial to ultrasonic cavitation. Besides, the acoustic flow action is strengthened with the increase of ultrasonic frequency and decrease of gas-liquid mixture's average density. For the designed sonoreactor, it is critical that high-frequency transducers should be determined near the bottom and upper region of the kettle, and large-amplitude transducers can be confirmed in the middle position. The research findings will provide theoretical and technical supports for developing state-of-the-art sonoreactors and optimizing ultrasonic process parameters in the industrialized preparation of nanocomposites.

Analysis of electrode locations on limb condition effect for myoelectric pattern recognition

BackgroundGesture recognition using surface electromyography (sEMG) has garnered significant attention due to its potential for intuitive and natural control in wearable human–machine interfaces. However, ensuring robustness remains essential and is currently the primary challenge for practical applications.MethodsThis study investigates the impact of limb conditions and analyzes the influence of electrode placement. Both static and dynamic limb conditions were examined using electrodes positioned on the wrist, elbow, and the midpoint between them. Initially, we compared classification performance across various training conditions at these three electrode locations. Subsequently, a feature space analysis was conducted to quantify the effects of limb conditions. Finally, strategies for group training and feature selection were explored to mitigate these effects.ResultsThe results indicate that with the state-of-the-art method, classification performance at the wrist was comparable to that at the middle position, both of which outperformed the elbow, consistent with the findings from the feature space analysis. In inter-condition classification, training under dynamic limb conditions yielded better results than training under static conditions, especially at the positions covered by dynamic training. Additionally, fast and slow movement speeds produced similar performance outcomes. To mitigate the effects of limb conditions, adding more training conditions reduced classification errors; however, this reduction plateaued after four conditions, resulting in classification errors of 22.72%, 22.65%, and 26.58% for the wrist, middle, and elbow, respectively. Feature selection further improved classification performance, reducing errors to 19.98%, 19.75%, and 27.14% at the respective electrode locations, using three optimal features derived from single-condition training.ConclusionsThe study demonstrated that the impact of limb conditions was mitigated when electrodes were placed near the wrist. Dynamic limb condition training, combined with feature optimization, proved to be an effective strategy for reducing this effect. This work contributes to enhancing the robustness of myoelectric-controlled interfaces, thereby advancing the development of wearable intelligent devices.

Performance analysis of shear horizontal one port surface acoustic wave (SAW) resonator for optimal liquid sensing based on finite element method

This paper presents the numerical study using finite element method for optimal liquid sensing performance of one port surface acoustic wave (SAW) resonator. Simulation shows that the extend of IDT-reflector gap can be optimized to contain most of the piezoelectric displacement. Various settings of liquid placement on the mentioned region yield distinct resonant frequency responses of the SAW sensor. For concentrated liquid with higher order of viscosity, magnitude of S-Parameter and phase of the propagating SAW can be applied to sense the liquid solutions. Based on the results, optimal liquid sensing performance of the device can be achieved when liquid droplet sized about 10 % of the aperture is placed in the middle position of the IDT-reflector gap conditioned at 1.5 λ. Using the formulated strategy, the one port SAW device distinguishes well 0 % to 100 % glycerine concentrations compared to limited detection range reported in the previous study. The finding includes equation of liquid turnover viscosity before shift in direction of the changes in S-Parameter measurement. The derived parameters can be set as reference to design the microfludic cell or lab-on-chip based on the one port SAW configuration for optimized liquid sensing performance.

Hydraulic and axial force characteristics of large axial flow pumps under different flow conditions

Abstract Axial flow pumps often experience uneven distribution of axial force on the blades when deviating from design conditions, which can easily lead to local damage to the pump blades. In response to this issue, this article conducts a detailed study on the hydraulic and axial force characteristics of large vertical axial flow pumping stations in China based on constant and non-constant numerical simulation research methods. Research has found that under biased operating conditions, due to the angle between the water flow direction inside the impeller and the impeller blades, the water body collides with the blades, resulting in concentrated pressure distribution on both sides of the inlet side of the impeller blades. Under low flow conditions, the high axial force area of the impeller blade is concentrated in the middle and rear position of the suction surface, while under high flow conditions, the high axial force area is widely distributed. Under the conditions of 0.8 Q to 1.4 Q, the fluctuation of axial force on the impeller blades is mainly affected by the rotation of the impeller blades. However, under low flow conditions, due to the turbulence of the flow state, there is no obvious pattern of axial force variation on the impeller blades. In addition, under different flow conditions, there is no obvious pattern in the fluctuation of axial force on the guide vanes. This also proves that there are problems such as uneven axial force distribution and no periodic changes in the impeller blades under low flow conditions, which can easily lead to damage to the impeller blades. The above analysis can provide some reference for the design of impeller blades.

Effect of Deposit Scale on Mechanical Properties of In-Situ Alloyed CrCoNi Medium Entropy Alloys Formed by Directed Energy Deposition

Directed energy deposition (DED), as an additive manufacturing technology, has shown unique advantages in multi-material additive manufacturing and remanufacturing. In this study, two types in-situ alloyed CrCoNi medium entropy alloys that have thin-walled structures with different thicknesses (T1 and T2) were manufactured by the DED process, and the mechanisms of differences in relative density, microstructure, and mechanical properties at different heights were systematically analyzed. In terms of microstructure, the T1 and T2 samples along the building direction exhibit significant differences in crystallographic orientation, grain size, and dislocation density, which are related to the local temperature gradient differences caused by the scanning path and heat accumulation. In terms of mechanical properties at different heights of the two types of thin-walled structures, the yield strength is higher but the elongation is lower at the bottom position of sample, while the yield strength is lower but the elongation is higher at the middle and top positions. The differences of mechanical properties at different heights of the T1 and T2 samples are related to the microstructure and relative density. This finding provides new insights for the design and performance analysis of complex thin-walled structures formed by additive manufacturing.

Relationship between the heterogeneity in mechanical properties, bone density and composition parameters of cortical bone to design and develop bone scaffolds and implants: Analysis of bone microstructure

Bone is heterogeneous and anisotropic because its mechanical characteristics vary by anatomic location and loading direction. Previous research established a correlation between bone density, mineral, organic content, and porosity and mechanical qualities. Medical and bioengineering researchers can learn about bone heterogeneity and anisotropy by analysing bone density and later composition parameters across the bone diaphysis in both longitudinal and transverse orientations. This research examines bone density and composition parameters in bovine femoral cortical bone from higher, middle, and lower diaphysis regions and longitudinal and transverse orientations. At three homogeneous diaphysis sites, these properties did not alter in longitudinal or transverse orientations. At the upper and lower diaphysis locations, mineral and organic content were statistically different in both longitudinal and transverse orientations, contributing to anisotropy. At the middle location, all measured parameters were not statistically different. Transverse bone density and water heterogeneity were greater, while longitudinal values were higher for the other metrics. Upper and lower sites had increased bone variability due to %water, although mineral content was more homogenous. The longitudinal and transverse organic content and apparent density heterogeneity was greater at the middle position. At the later site, bone density and mineral content were more homogenous longitudinally and transversely. Lamellar bone microstructure with canalicular/vascular network, cavities, and holes contributed to bone materials' %water content. Collagen fibres contributed to bone material's organic composition, whereas intrafibrillar and extra fibrillar minerals contributed to its mineral content.

Gradation optimization of AC-20 asphalt mixture based on the fuzzy analytic hierarchy process and comprehensive evaluation method

The aggregate gradation of asphalt mixture is one of the most important factors affecting the service life of asphalt pavement. In order to study the gradation of asphalt mixture with the best comprehensive performance, this study puts forward a new method of mineral aggregate gradation optimization based on the fuzzy analytic hierarchy process and comprehensive evaluation method, aiming at the multi-level and multi-index evaluation of the road performance of asphalt mixture. First, the orthogonal test design method is applied to design nine target gradations with coarse aggregate (&amp;gt;4.75 mm) and fine aggregate (&amp;lt;4.75 mm) of AC-20 (asphalt concrete) mixture serving as two factors and the upper, middle, and lower positions of the gradation curve as three levels, and then the road performance test research is carried out. Second, a comprehensive model for evaluation of road performance of mineral aggregate gradation is established. A fuzzy complementary judgment matrix is constructed, and the index weights of each level and the hierarchical total ranking weight are calculated. Then, the membership function is introduced into the comprehensive evaluation model for the road performance of mineral aggregate gradation, and the membership values of each index of asphalt mixture road performance are obtained. Finally, the fuzzy comprehensive evaluation method is used to find out the comprehensive evaluation value of the road performance of the nine graded asphalt mixtures, and the mineral aggregate gradation is optimized. The research results show that the 1# gradation of the asphalt mixture has the highest comprehensive road performance evaluation value, and the combination of the fuzzy hierarchical analysis process and comprehensive evaluation method can more objectively and comprehensively evaluate the comprehensive road performance of the asphalt mixture and provide a useful reference for the optimal selection of asphalt mixture mineral gradation.

Современные тенденции репродуктивных потерь в Хабаровском крае

Abstract The relevance of the problem. Demographic processes are an urgent problem for the Far East and the Khabarovsk Krai. The objective of this study was to examine current trends in reproductive losses in Khabarovsk Krai in comparison with data for the Russian Federation and the Far Eastern Federal District. Material and research methods. The comparative analysis method is used in the article. The source of information was publications in Russian scientific journals and monographs, the data obtained from the official web sites of Rossstat of the Russian Federation and the Khabarovsk Krai, as well as statistical materials published by the Medical Information and Analytical Center of the Ministry of Health of the Khabarovsk Krai for 2019–2022. For the period of preparation of the material, the data of Russia's Rosstat for 2023 on maternal and infant mortality in the official access was not available. Results and discussion. A comparative analysis of maternal, perinatal and infant mortality, as well as stillbirth in the context of federal districts, subjects of the Far Eastern Federal District and the Khabarovsk Krai in 2019–2022 has shown that in all 4 indicators the most disadvantaged in the Russian Federation are the Siberian and Far Eastern Federal Districts, as well as the North-West Federal District (except for the infant mortality rate). In the Far Eastern Federal District, the most disadvantaged subjects in terms of all indicators were the Chukotka Autonomous Okrug, the Jewish Autonomous Oblast and the Trans -Baikal Territory, as well as the Kamchatka Oblast (with the exception of an indicator of stillbirth). The Khabarovsk Krai in all aspects has got the middle position. In the Khabarovsk Krai, special attention is required in terms of stillborn and perinatal mortality of Okhotsk and Nikolaevsky-on-Amur municipal areas. Conclusions. The study of reproductive losses in Khabarovsk Krai allows us to determine the risks and priorities for the development of demographic processes. The analysis has shown that the region took a middle position in terms of maternal, perinatal and infant mortality rates in 2019–2022 compared to data for the Russian Federation and the Far Eastern Federal District. At the same time, during the study period, there was a sharp increase in maternal mortality from 6.93 cases in 2019 to 15.5 cases in 2022 per 100,000 births, which indicates the insufficient effectiveness of health authorities and medical organizations in preventing it.

Visualization experimental study on the boiling characteristics of vapor chamber evaporator surface with different heat sources

The effective functioning of vapor chambers depends on the phase change of the working fluid at the wick surface. Given the prevalent role of vapor chambers in thermal management in the electronics industry, it is critical to study the boiling characteristics and thermal performance of vapor chambers, as well as the effect of heat source conditions. In this work, to observe phase change at the wick surface, the visualization confined chamber with wick (VCCW) is proposed and fabricated, which features a side window and a 2 mm thick wick sintered with aluminum powders. The working fluid used is acetone. The heat source is designed in three different sizes to heat the VCCW in either the middle or right position. The experimental results show that the boiling curve is divided into four stages. In the stage Ⅰ, the boiling curve is linear, and the visualization results reveal that the phase change phenomenon on the wick surface is evaporation. The Ⅱ stage is defined as ONB (Onset of Nucleate Boiling) for the vapor chamber evaporator surface. The boiling curve shows a turning, and bubbles were observed to appear and spread by visualization. In the Ⅲ and Ⅳ stages, the boiling curve remains linear. The stable nucleate boiling and intermittent local dryout is observed before and after the DNB (Departure from Nucleate Boiling). The slope of the boiling curve increases as the size of the heat source enlarges, which contributes to greater superheat and evaporation of the working fluid at smaller heat fluxes. Moreover, the position and size of the heat sources affect the ONB and DNB due to heat diffusion and capillary-driven supply of fluid.

Cascaded lattice Boltzmann simulation of Newtonian and non-Newtonian mixture nanofluids with variable thermophysical properties in a cavity with vertical heat radiator

The central moments-based cascaded lattice Boltzmann method (CLBM) for then Newtonian and non-Newtonian Buongiorno’s model mixture nanofluids (CuO, ZnO, Al2O3-water) has been implemented and applied in a square chamber with a vertical heat radiator using accelerated graphics processing unit (GPU) computing through compute unified device architecture (CUDA) C/C++ platform. Due to the higher numerical stability, the CLBM is a superior numerical tool to the raw moments-based MRT-LBM (multiple-relaxation-time lattice Boltzmann method). Three different models for the viscosity and thermal conductivity of the nanofluids: (i) the Binkmann model for the constant viscosity and the Maxwell model for the constant thermal conductivity (ii) Binkmann and Maxwell model with temperature dependent Brownian motion and (iii) Corcione model with non-Newtonian fluid where the temperature and strain rate determine the nanofluid effective thermal conductivity and viscosity, have been used. The enclosure’s upper and bottom walls are thermally adiabatic, but the left and right walls are uniformly cold. A vertical heater is immersed in the middle position of the cavity. The benchmark results for non-Newtonian, Newtonian, and nanofluids for the various computational domains are used to validate the current code adequately. The Bingham number (Bn), the Rayleigh number (Ra), and The volume fraction of the nanoparticles (ϕ) are the three key parameters that are varied in this investigation to demonstrate the effects of natural convection on the isotherms, streamlines, isolines of nanoparticle volume fractionation, yielded and unyeilded zone, and average Nusselt number (Nu¯). The Brownian motion effects of the nanoparticles augmented the average rate of heat transfer and the use of the Bingham nanofluids reduced the heat transfer enhancement. For the CuO-water nanofluid, the augmentation of the rate of heat transfer is 15.42% from ϕ=0 to 4% while Ra=106 and the corresponding heat transfer enhancement for the ZnO-water nanofluid is 11.11%. For the Bingham fluid, the rate of heat transfer increases 7% from Ra=105 to Ra=106 while ϕ=2% and Bn=0.3. The findings can be applied to optimize automotive radiator systems, which are crucial for maintaining engine temperature.

Frequency, localization, and diameter of the accessory maxillary ostium and its relationship with sinus pathologies and nasal cavity variations: an anatomical study based on cone beam computed tomography.

The aim of the present study was to determine the presence, frequency, and characteristics of the accessory maxillary ostium (AMO) in a specific Turkish population using cone beam computed tomography (CBCT) and to evaluate the frequency of pathologies and anatomical variations in the nasal cavity and maxillary sinus and to assess their relationship with the AMO. This study retrospectively evaluated the presence of AMO in CBCT images of 543 patients, the patients' age, gender, and dentition status, the presence of nasal cavity variations and maxillary sinus pathologies, and their relationship to the presence of AMO. Descriptive values of the data and comparative results were included. 249 males and 294 females participated in the study. The majority of right and left sinus pathologies were irregular type mucosal thickenings (right/left; 14%, 14.9%). The majority of nasal variations were concha bullosa (right/left; 37.9%, 39.2%). There were 148 (27.3%) and 138 (25.4%) AMOs on the right and left sides, respectively, with the majority in the middle position (right/left; 21.2%/17.5%). The frequency of right and left AMOs was significantly higher in men (P = 0.019 and P = 0.020, respectively). The left AMO frequency was significantly higher in patients with left-sided sinus pathology (P = 0.003). AMO diameters were larger in men (right/left P = 0.010 and P = 0.021, respectively), and left AMO diameter was significantly larger in patients with left sinus pathology (P = 0.006). Before any surgical intervention in the maxillary sinus and osteomeatal region, the presence and location of the AMO, existing pathologies, and variations in the region should be carefully checked to avoid complications.

Critical success factors for ergonomics programs and their relationship to benefits of health and safety in Mexico’s manufacturing industries

This research determines the critical factors for implementing ergonomics programs related to health and safety benefits in the manufacturing industries of Ciudad Juarez, Mexico, from the middle/upper management perspective. The sample was non-probabilistically selected for convenience, comprising individuals in middle and senior management positions. An original questionnaire containing 105 items measuring five latent variables was developed, reviewed, and validated for data collection. The sample size totalled 206 participants. Structural equation models using partial least squares (PLS) were employed to analyse interrelationships between variables. This research demonstrated acceptable reliability and quality indices. Management commitment emerged as the most significant factor, exerting the highest direct, indirect, and total effects on the work environment and prevention activities, significantly enhancing health and safety benefits. Consequently, manufacturing companies in Juarez City must strive to improve management commitment in the working environment and prevention activities since both strategies can increase employee health and safety benefits.

Application of fallout radionuclide—137Cs for estimating soil erosion in steep hillslopes with diverse land use of North-western Indian Himalayas

Hilly and mountainous regions are significantly impacted by soil erosion, primarily due to rainfall-runoff processes occurring on the hillslope scale. Assessing soil erosion is crucial for quantifying the loss of soil carbon and nutrients, which diminishes the potential of soil ecosystem services and is critical for mitigating the impacts of climate change on food security. However, the Himalayan landscape poses serious challenges for assessing soil erosion due to its steep and rugged terrain, which hinders the use of conventional and modelling methods. The fallout radionuclide—137Cs has been extensively utilized as an environmental marker for investigating soil redistribution processes. Despite its potential, there is a notable lack of 137Cs-based soil erosion studies in the Himalayan region. In this context, we assessed the applicability of the fallout radionuclide—137Cs method in quantifying soil erosion rates and identifying erosion hotspots on two hillslopes of the Higher Himalayas. On the hillslope scale, we observed that soil erosion rates vary based on slope gradient and land use/land cover. Forested areas exhibited the lowest soil erosion rates compared to cultivated areas, while flat hillslope positions experienced lower erosion rates than steeper positions. The average net erosion rate for the Harsil hillslope varied among different hillslope positions, ranging from – 2.9 to – 15.6 t ha−1 yr−1. Similarly, in the Gangnani hillslope, the net erosion rates varied across different positions, ranging from – 5.6 to – 39 t ha−1 yr−1. Our findings confirm that the middle and lower hillslope positions are the most critical source areas with higher soil erosion rates, while hillslope positions with forest cover demonstrate the lowest erosion rates, identified as helpful in controlling soil erosion. The study has demonstrated the applicability of FRN as a soil erosion measurement method in the complex, rugged, and steep terrain of the Himalayas, highlighting the need for targeted conservation efforts to mitigate soil erosion and preserve ecosystem integrity.

Effects of Terracing on Soil Aggregate Stability and Erodibility in Sloped Farmland in Black Soil (Mollisols) Region of China

Soil aggregates are important indicators of soil structure stability and quality. The black soil region of northeast China, known for its high agricultural productivity, faces significant challenges due to soil erosion. This study investigates the impact of terracing on the stability and erodibility characteristics of soil aggregates in sloped farmlands, which is crucial for this important agricultural area. Three research sites with the same basic management modes were selected along a latitudinal gradient, from the mid-temperate zone to the cold temperate zone, in the black soil region of northeast China. The Savinov method was used to analyze the differences in soil aggregate size distribution, stability characteristics, and soil erodibility between terraced and non-terraced slopes at each research site. The results showed that terracing increased the content of large soil aggregates (&gt;0.25 mm) by 5.38–6.35%, with the increase becoming more pronounced from north to south. The improvement in soil structure varied by location and slope position, with the most significant improvement at the middle slope position. Terracing enhanced soil aggregate stability, reduced soil erodibility, and improved soil structure by increasing clay and soil organic matter (SOM) content and reducing soil bulk density (BD), promoting the conversion of small aggregates to large aggregates. Soil stability indicators such as water-stable aggregates (WSAs), mean weight diameter (MWD), and geometric mean diameter (GMD) were dominated by aggregates &gt; 5 mm, while erodibility indicators such as fractal dimensions (Ds) and the soil erodibility factor (K values) were mainly influenced by aggregates &lt; 0.25 mm. Terraces can improve the soil structure and stability of sloping farmland by increasing the content of large soil aggregates and enhancing overall soil quality. The benefits of these improvements increase with latitude. These findings provide critical insights for determining effective management practices for sloped farmlands in the black soil region under various site conditions. They offer scientific evidence for preventing soil erosion and improving soil quality, thus supporting the sustainable development strategy for protecting black soil and ensuring long-term agricultural productivity.

Experimental study on multi-point ignition of NH3/air by high-frequency nanosecond dielectric barrier discharge

Non-equilibrium plasma ignition technology, with its ability to expand ignition limits and increase ignition volume, is considered an important development direction of advanced ignition systems, and has significant advantages in improving ignition stability and combustion rate. This study investigates the ignition and combustion assistance effect of high-frequency nanosecond surface dielectric barrier discharge (nSDBD) on NH3/air mixture in a constant volume combustion chamber (CVCC). The study reveals the influence of high-frequency nSDBD on the growth process of the flame kernel in NH3/air mixture. As the discharge pulse number (PN) increases, the flame kernel develops from the middle position of the discharge filament to the head of the discharge filament, while there is no obvious flame at the root and middle of the discharge filament. Continuous discharge causes the flame kernel to appear concave and the center of the flame kernel to shift towards the wall of the CVCC. In the NH3/air mixture, the initial flame kernels exhibit dissipation phenomenon, resulting in a discrepancy between the number of initial flame kernels and the number of stable combustion flame kernels. As the discharge frequency or pulse number increases, and the number of stable combustion flame kernel increases. The adjustment of discharge frequency and pulse number can effectively control the flame development time (FDT) and flame rise time (FRT) of NH3/air mixture. As PN increases, both FDT and FRT are shortened. When discharge frequency is 20 kHz, the maximum shortening of FDT and FRT are 30 ms and 14 ms, respectively, about 55 % and 30 %. The effects of discharge frequency on FDT and FRT exhibit a non-monotonic variation pattern, and it is necessary to comprehensively consider various discharge parameters to achieve the best ignition effect. The ignition success rate curve of high-frequency nSDBD in NH3/air mixture is steep. The study results of this paper provide new discoveries and experimental data for advanced ignition systems.

Oscillation mechanism and predictive model of explosion load for natural gas in confined tube

Gas explosion in confined space often leads to significant pressure oscillation. It is widely recognized that structural damage can be severe when the oscillation frequency of the load resonates with the natural vibration frequency of the structure. To reveal the oscillation mechanism of gas explosion load, the experiment of gas explosion was conducted in a large-scale confined tube with the length of 30 m, and the explosion process was numerically analyzed using FLACS. The results show that the essential cause of oscillation effect is the reflection of the pressure wave. In addition, due to the difference in the propagation path of the pressure wave, the load oscillation frequency at the middle position of the tunnel is twice that at the end position. The average sound velocity can be used to calculate the oscillation frequency of overpressure accurately, and the error is less than 15%. The instability of the flame surface and the increase of flame turbulence caused by the interaction between the pressure wave and the flame surface are the main contributors to the increase in overpressure and amplitude. The overpressure peaks calculated by the existing flame instability model and turbulence disturbance model are 31.7% and 34.7% lower than the numerical results, respectively. The turbulence factor model established in this work can describe the turbulence enhancement effect caused by flame instability and oscillatory load, and the difference between the theoretical and numerical results is only 4.6%. In the theoretical derivation of the overpressure model, an improved model of dynamic turbulence factor is established, which can describe the enhancement effect of turbulence factor caused by flame instability and self-turbulence. Based on the one-dimensional propagation theory of pressure wave, the oscillatory effect of the load is derived to calculate the frequency and amplitude of pressure oscillation. The average error of amplitude and frequency is less than 20%.

Who thinks ideologically about welfare state reform? Partisanship and attitude consistency in politicians’ and mass public perceptions about the consequences of welfare service privatization in Sweden

When studying attitudes toward the welfare state or evaluations of welfare reforms, research has tended to focus on what people think rather than how they think about specific issues. Moreover, the effects of the mobilizing efforts of political parties on attitudes and belief systems are often theorized separately from the normative institutional feedback effects common to the welfare state literature. In this paper, I propose that elite political rhetoric and institutional norms may exert dual pressures leading to partisan differences in the propensity to think ideologically among the mass public, defined as a positive relationship between holding internally consistent attitudes and taking a partisan issue position. Drawing on the case of welfare service privatization in Sweden, I point out how the rhetoric of the right – emphasizing choice and private property – frequently contradicts norms about universality long espoused by the Swedish welfare state, while the rhetoric of the left – emphasizing equality of access and outcomes – is better aligned with such institutional norms. The analysis of survey data demonstrated that centre-right sympathizers, the prime receivers of conflicting elite versus institutional messages, frequently took a middling position, being neither positive nor negative, to the consequences of welfare service privatization, and that, unlike centre-right politicians and sympathizers and politicians of left parties, this position did not differ according to attitude consistency. Furthermore, political interest enhanced this relationship among right sympathizers but was of little consequence to left sympathizers, implying that in the case of a conflict between institutional norms and political rhetoric, only the most attentive sympathizers are likely to engage in ideological thinking on the basis of partisanship.