Exchange Characteristics Research Articles

Energy exchange mechanism between blast wave and expansion tube

The mechanical response and energy absorption characteristics of the energy-absorbing structure under blast loading are widely concerned in engineering protection, while the energy exchange mechanism remains poorly understood, thereby limiting improvements in energy absorption performance under blast loading. This paper utilizes the expansion tube structure (ETS) as a typical energy-absorbing structure to investigate the energy exchange mechanism under blast loading. Following an experimental verification, numerical simulations are conducted to investigate the effect of relevant parameters on the energy exchange characteristics. A theoretical model based on the strong-shock hypothesis is developed and validated against numerical results to predict the energy absorption efficiency of ETS under blast loading. The findings reveal that increasing the areal density of ETS positively impacts impulse transfer, but does not contribute significantly to energy exchange between the blast wave and ETS. Notably, there exists a significant negative correlation between the energy exchange efficiency and areal density. An approximately linear positive correlation is observed between the energy exchange efficiency and both peak overpressure and specific impulse of the reflected wave due to an enhanced reflection coefficient of the blast wave. Moreover, increasing equivalent strength leads to a decrease in energy exchange efficiency as it negatively correlates with effective impulse of the reflected wave. This study elucidates the underlying mechanisms governing energy exchange in expansion tube under blast loading, providing valuable insights for optimizing designs of energy-absorbing structures.

Nanoparticles synergy: Enhancing wheat (Triticum aestivum L.) cadmium tolerance with iron oxide and selenium

Nanotechnology is capturing great interest worldwide due to their stirring applications in various fields and also individual application of iron oxide nanoparticle (FeO − NPs) and selenium nanoparticles (Se − NPs) have been studied in many literatures. However, the combined application of FeO and Se − NPs is a novel approach and studied in only few studies. For this purpose, a pot experiment was conducted to examine various growth and biochemical parameters in wheat (Triticum aestivum L.) under the toxic concentration of cadmium (Cd) i.e., 50 mg kg−1 which were primed with combined application of two levels of FeO and Se − NPs i.e., 15 and 30 mg L−1 respectively. The results showed that the Cd toxicity in the soil showed a significantly (P < 0.05) declined in the growth, gas exchange attributes, sugars, AsA-GSH cycle, cellular fractionation, proline metabolism in T. aestivum. However, Cd toxicity significantly (P < 0.05) increased oxidative stress biomarkers, enzymatic and non-enzymatic antioxidants including their gene expression in T. aestivum. Although, the application of FeO and Se − NPs showed a significant (P < 0.05) increase in the plant growth and biomass, gas exchange characteristics, enzymatic and non-enzymatic compounds and their gene expression and also decreased the oxidative stress, and Cd uptake. In addition, individual or combined application of FeO and Se − NPs enhanced the cellular fractionation and decreases the proline metabolism and AsA − GSH cycle in T. aestivum. These results open new insights for sustainable agriculture practices and hold immense promise in addressing the pressing challenges of heavy metal contamination in agricultural soils.

Theoretical model for high-altitude gas exchange process in multi-fuel poppet valves two-stroke aircraft engine

Under the demand of global aviation carbon reduction, the multi-fuel poppet valves two-stroke (MF-PV2S) aircraft engine exhibits advantages such as lower lubricant consumption and the flexibility to high-altitude valve timing adjustment, which position it to play a more significant role in general aviation aircraft and unmanned aerial vehicle propulsion systems. High-altitude gas exchange performance is a critical factor in the thermal efficiency and power characteristics of two-stroke aircraft engines. However, the applicability and accuracy of existing models in predicting the gas exchange process for PV2S engines remain insufficiently discussed. Recognizing discrepancies in the predictions of PV2S gas exchange processes by existing models, a theoretical model applicable to high-altitude gas exchange in an MF-PV2S aircraft engine is established. The modified model adjusts the exhaust composition during the second and third phases of the scavenging process, and a novel model characteristic coefficient, designated as b3, is incorporated to signify the proportion of mixed gas in the exhaust gases at a given moment. Moreover, the model characteristic coefficients b1 and b2, are determined with nonlinearity, based on appropriate relationships that account for the characteristics of the PV2S gas exchange process. The model calculates gas exchange characteristics under different operating conditions and fuels, comparing these results with simulations and tracer gas-based experiments. The findings demonstrate that the model successfully captures the characteristics of early appearance and prolonged duration of fresh charge loss during PV2S gas exchange, significantly enhancing the predictive accuracy. Through adjustments of model coefficients based on specific conditions, the model predicts and describes the variation process of PV2S gas exchange performance parameters under different conditions, including various speeds, different intake-exhaust pressure differences at different altitudes, valve overlaps, and fuel types. The maximum relative errors between model predictions and experimental trapping efficiency, delivery ratio and charging efficiency are 2.58 %, 4.33 %, and 3.89 % respectively. The model can be used for rapid and accurate prediction of gas exchange characteristics under different conditions for the MF-PV2S aircraft engine. Also, it serves as an alternative model of three-dimensional simulation models that can be coupled into the one-dimensional thermodynamic cycle simulation.

Combined exposure of PVC-microplastic and mercury chloride (HgCl2) in sorghum (Pennisetum glaucum L.) when its seeds are primed titanium dioxide nanoparticles (TiO2-NPs).

The present work studied the impact of different levels of PVC-microplastics (PVC-MPs), namely 0 (no PVC-MPs), 2, and 4mg L-1, along with mercury (Hg) levels of 0 (no Hg), 10, and 25mgkg-1 in the soil, while concurrently applying titanium dioxide-nanoparticles (TiO2-NPs) at 0 (no TiO2-NPs), 50, and 100µgmL-1 to sorghum (Pennisetum glaucum L.) plants. This study aimed to examine plant growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress indicators, and the response of various antioxidants (enzymatic and non-enzymatic) and their specific gene expression, proline metabolism, the AsA-GSH cycle, and cellular fractionation in the plants. The research outcomes indicated that elevated levels of PVC-MPs and Hg stress in the soil notably reduced plant growth and biomass, photosynthetic pigments, and gas exchange attributes. However, PVC-MPs and Hg stress also induced oxidative stress in the roots and shoots of the plants by increasing malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EL) which also induced increased compounds of various enzymatic and non-enzymatic antioxidants and also the gene expression and sugar content. Furthermore, a significant increase in proline metabolism, the AsA-GSH cycle, and the pigmentation of cellular components was observed. Although, the application of TiO2-NPs showed a significant increase in plant growth and biomass, gas exchange characteristics, enzymatic and non-enzymatic compounds, and their gene expression and also decreased oxidative stress. In addition, the application of TiO2-NPs enhanced cellular fractionation and decreased the proline metabolism and AsA-GSH cycle in P. glaucum plants. These results open new insights for sustainable agriculture practices and hold immense promise in addressing the pressing challenges of heavy metal contamination in agricultural soils.

Correlative variation of economically valuable traits in South Kazakh Merino.

Fine-fleeced sheep are distinguished by numerous economically valuable traits that constitute the foundation for productive distinctions among breeds, populations, lines, and individuals. Many of these traits have already been mentioned or thoroughly examined during studies on the correlative variability of productivity indicators, blood parameters, characteristics of pulmonary gas exchange, histological structures of the skin, and features of the experimental sheep's coat. The objective of our research was to investigate the correlative variability of key economically valuable traits that characterize the overall functional state of sheep organisms under varying environmental conditions. The study was conducted at the "Sharbulak" breeding farms and the "Samat" peasant farms in the Kazygurt district of the Turkestan region. Our findings reveal that one-year-old rams surpass ewes in terms of live weight by 32-37% and in terms of unwashed wool shearing by 21-23%. Two-year-old rams outperform ewes in live weight by 2.15-2.17 times and in unwashed wool shearing by 2.38-2.44 times. The highest phenotypic variability in relative terms (as indicated by the coefficient of variation) is observed in the shearing of pure wool, with an average coefficient of variation of 18.1% across all sex and age groups of sheep. This is followed by the wool coefficient (17.4%) and the yield of pure fiber (12.5%). For each group of animals, the most substantial phenotypic correlation coefficients were observed between the live weight of sheep and the shearing of unwashed wool. On average, across all groups of sheep at the "Sharbulak" breeding farm, this phenotypic correlation reaches +0.411 ± 0.077. Correspondingly, for the sheep herd at the "Samat" peasant farm, it is +0.326 ± 0.075. The second-highest phenotypic correlation pertains to the cut of unwashed wool and the length of wool (with correlation coefficients of +0.156 ± 0.058 and +0.145 ± 0.057, respectively, for the herds). The third-highest correlation involves live weight and wool length (+0.131 ± 0.085 and +0.105 ± 0.078, respectively). No statistically significant differences were identified in the average correlation coefficients between the live weight of sheep, the shearing of unwashed wool, and the length of the staple among the flocks of sheep at the "Sharbulak" breeding farm and the "Samat" peasant farm.

Oxygen dynamic exchange and diffusion characteristics of ZnO nanorods from 17O MAS NMR.

Interactions of ZnO nanorods with water and the dynamic migration characteristic of surface oxygen species are important in controlling its structure and catalytic properties. Here, we apply 17O solid-state NMR spectroscopy to investigate the interactions, as well as oxygen ion diffusion properties of ZnO nanorods under different conditions.

Sorption and mass exchange characteristics of extrudates enriched with cocoa bean shells

The aim of the experimental work was to determine the sorption isotherms of wheat extrudates enriched with cocoa bean shells at different temperatures (10 °C, 25 °C, 40 °C) and water activities (0.11 to 0.85) using the static gravimetric method. Five three parameter models (Chung-Pfost, Halsey, Oswin, Henderson, GAB) were applied to survey the experimental data. It was established that the isotherms demonstrate Types II, according to the Brunauer’s classification and the Oswin and Chung-Pfost models were suitable for describing the relationship between the equilibrium moisture content and the water activity. The monolayer moisture content was established using the Brunauer-Emmett-Teller equation and ranged within 5.08 % d.b. and 7.80 % d.b., respectively. The increase of temperature decreases the sorption characheristics of the examined extrudates. The specific surface area of sorption for wheat extrudates enriched with cocoa bean shells varies between 181.59 (m2/g) and 278.82 (m2/g). It was found that the increase of temperature of the matrix in the range of 10 °C to 40 °C decreases the values of monolayer moisture content and the specific surface area of sorption.

Numerical simulation on water exchange affected by tidal and runoff in Xiaohai Lagoon, Hainan province

Xiaohai Lagoon is the largest lagoon in Hainan, connected to the open sea through a narrow channel. In this study, a hydrodynamic numerical model based on the FVCOM model is established to quantitatively investigate the water exchange characteristics between Xiaohai Lagoon and the open sea under tidal and runoff conditions, utilizing concepts such as residual flow, tidal prism, and half-life time. Under the influence of runoff effect, the water exchange capacity in the lagoon has significant spatial variations, and the closer the distance to the estuary and inlet compared to the tidal drive, the faster the water exchange. The strongest areas of water exchange capacity in the Xiaohai lagoon are located in the mouth, tidal channel and estuary areas, and the weakest area is the southeastern part of the lagoon. The simulation results showed that the runoff input has a certain promotion effect on the water exchange in the lagoon, especially in the scouring effect of freshwater in the estuary area, the easier the water exchange between the sea areas.

Mass-moisture exchange characteristics of carrots

Some thermodynamic characteristics of carrots were calculated and analyzed based on known experimental data - the binding energy of water with the material and the specific isothermal moisture capacity. An innovative nomogram is presented, which can be successfully used for easy and quick determination of the binding energy of water. An empirical equation (third degree polynomial) for the specific isothermal moisture capacity is derived. All results in the paper will be used to design dryers and drying processes for this product.

Heat exchange characteristics of underground and pavement buried pipes for bridge deck heating conditions.

Geothermal energy is increasingly employed across diverse applications, with bridge deck snow melting emerging as a notable utilization scenario. In Jinan city, China, a project is underway to utilize ground source heat pumps (GSHPS) for heating bridges. However, essential operational parameters, including fluid medium, temperature, and heat exchange details, are currently lacking. This study addresses the thermal design challenges associated with ground heat exchangers (GHE) for bridge heating through a combination of numerical modeling and field experiments. Utilizing software Fluent, a refined three-dimensional multi-condition heat transfer numerical analysis was carried out. Field tests based on actual operating conditions were also conducted and the design parameters were verified. The results indicate that an inlet temperature of 5°C and an aqueous solution of ethylene glycol with a mass concentration of 35% as the heat exchange medium are suitable for the GSHPS in Jinan; Moreover, the influence of backfill material and operation time on the heat transfer efficiency was revealed and the suitable material with 10% bentonite and 90% SiO2 was suggested; Finally, based on the influence of the pipe spacing on the heating characteristics of bridge deck, the transition spacing of 0.2 m is given for the temperature response of the bridge deck. This comprehensive study contributes valuable insights through simulation and experimental analysis of the thermal environment variation, aiming to advance the development of GSHPS for bridge deck heating in Jinan, China.

Особенности нестационарных тепломеханических процессов в выпускном коллекторе автомобильного поршневого двигателя размерности 8,2/7,1

The purpose of this work was to obtain experimental data on unsteady gas dynamics and the intensity of heat transfer of the flow in the exhaust system of an automobile piston engine for different initial conditions. The research was carried out on an experimental stand simulating the exhaust process in a piston engine in dynamics. The pressure at the outlet (in the cylinder) varied from 0.05 to 0.2 MPa, the speed of rotation of the crankshaft - from 600 to 3000 min-1. The method of thermal anemometry was used to determine the gas dynamic, flow and heat exchange characteristics of the flow in the exhaust system. Data on the instantaneous values of the velocity and local heat transfer of the flow in the exhaust system for different boundary conditions are presented in the article. The effect of the outlet pressure on the gas flow through the exhaust system and the level of heat transfer was analyzed. The spectral analysis of changes in the local flow velocity in the exhaust system is additionally presented in the article. The obtained patterns are useful in the applied aspect for clarifying engineering methods for calculating the exhaust system and for verifying mathematical models of gas exchange processes in automotive piston engines.

Influence of the Channel Design on the Heat Exchange Characteristics of Pulsating Flows in the Supply System of an Engine

Influence of the Channel Design on the Heat Exchange Characteristics of Pulsating Flows in the Supply System of an Engine

Using Carbon Stable Isotopes to Study C3 and C4 Photosynthesis: Models and Calculations.

Stable carbon isotopes are a powerful tool to study photosynthesis. Initial applications consisted of determining isotope ratios of plant biomass using mass spectrometry. Subsequently, theoretical models relating C isotope values to gas exchange characteristics were introduced and tested against instantaneous online measurements of 13C photosynthetic discrimination. Beginning in the twenty-first century, laser absorption spectroscopes with sufficient precision for determining isotope mixing ratios became commercially available. This has allowed collection of large data sets at lower cost and with unprecedented temporal resolution. More data and accompanying knowledge have permitted refinement of 13C discrimination model equations, but often at the expense of increased model complexity and difficult parametrization. This chapter describes instantaneous online measurements of 13C photosynthetic discrimination, provides recommendations for experimental setup, and presents a thorough compilation of equations available to researchers. We update our previous 2018 version of this chapter by including recently improved descriptions of (photo)respiratory processes and associated fractionations. We discuss the capabilities and limitations of the diverse 13C discrimination model equations and provide guidance for selecting the model complexity needed for different applications.

Corporate fraud, inertia and market conditions in explaining the differences in the exchange characteristics of bonds in the Russian market

Subject. This article deals with the empirical tests of asset pricing models with Russian bonds. Objectives. The article aims to analyze risk factor sensitivities for bond portfolios using asset pricing models with prominent factors and newly proposed risk factors, based on bond market fundamental anomalies, and identify term structure of factor loadings through hidden bond market states corresponding to business cycle stages. Methods. We used the Hidden Markov Model to recover the sequence of bond market states based on spread of ten-year minus three-month government bond yields. Results. The article provides evidence of the significant contribution of the newly proposed risk factors, corresponding with corporate fraud, and momentum factors to the explanatory power of asset pricing models for bond portfolios excess returns. Specifically, we find a strong idiosyncratic momentum effect in the cross-section of Russian bond returns and hence introduce a bond idiosyncratic return momentum factor. We introduce hidden bond market states based on spread of government bond yields and show that proposed market states are statistically and economically significant. We examine the state-dependent explanatory power of the risk factors for test portfolios. Conclusions. The study contributes to the risk estimation accuracy, and presents theoretical framework and empirical evidence of factor-based investing in fixed income instruments. Investors in the Russian bond market should account for bond exposure to the newly proposed risk factors in the risk-adjusted performance analysis of bond portfolios.

Mathematical model analysis for hydromagnetic flow of micropolar nanofluid with heat and mass transfer over inclined surface

In this study, a mathematical model analysis is made to figure out the impacts of relevant thermophysical effects on the rates of micropolar nanofluid transport phenomena near an inclined exponentially stretching surface. The flow phenomena are described mathematically using partial differential equations and simplified to dimensionless ordinary differential forms via suitable transformation variables. The resulting nonlinear coupled differential equations are then solved by using the optimal homotopy analysis method and the validity of the method is verified in convergence and comparative analysis. The rates of linear momentum, angular momentum, heat exchange and mass diffusion characteristics are investigated against continuous variations of pertinent parameters. Graphical elucidations are preferred to present the results of the study in detail. It was found that the rate of heat exchange is intensified with increasing values of micropolar parameter, Soret number and forces of buoyancy. Also, the rate of couple stress grows for higher estimation of micropolar parameter, surface shrinking, angle of inclination and heat sink parameter values. Further, the wall shear stress is strengthened for increasing values of the micropolar parameter, Dofour number, Soret number, buoyancy forces, heat release, chemical reaction and thermophoresis effects. On the other hand, the Sherwood number is enlarged with higher values of surface stretching parameter, medium porosity, Dufour number, chemical reaction, forces of buoyancy, heat release and Schmidt number.

THE IMPACT OF GOVERNANCE STRUCTURES ON ECONOMIC GROWTH IN AFRICA: A PANEL DATA ANALYSIS OF 47 AFRICAN COUNTRIES

Major international institutions like the World Bank, African Union, and International Monetary Fund have made the development of robust governance systems a “sacred utterance” since the 1990s. Our study aimed to refute this common thinking by examining how governance structures have affected the expansion of the financial market in 47 African countries from 2008 to 2019. Using the availability of venture capital as a proxy for financial market development, our article departed from existing literature which used stock exchange characteristics as benchmarks for growth in the financial market. The governance variables comprise the six global governance indices: control of corruption, government effectiveness, political stability, regulatory quality, the rule of law, and voice and accountability. The model’s control variables include GDP per capita, inflation, and trade openness. Our finding suggests that a great quality governance climate is significant in explaining the growth of the financial market in Africa using the generalized method of moments (GMM) methodological approach with corrected standard errors. Considering these findings, our research makes the case that solid institutional frameworks might encourage the degree of financial systems growth in Africa. Therefore, the financial development rate in the African region will be significantly influenced by improving the quality of governance through strengthening legal and institutional frameworks to facilitate financial inclusion.

Flow Structures in Open Channels with Emergent Rigid Vegetation: A Review

On the edges of rivers where the flow velocity is low, aquatic plants flourish, with emergent rigid herbs being the most common. Since the flow structures of vegetated flow are strongly influenced by vegetation distribution patterns, homogeneous and heterogeneous canopies are defined based on the characteristics of vegetation distribution. A review summarizing recent advances in flow structures under the influence of different types of canopy arrangements, including ribbon-like homogeneous canopies, ribbon-like heterogeneous canopies, and patched heterogeneous canopies, is needed. Their flow development process, shear layer properties, coherent structure features, and momentum exchange characteristics are summarized, and a future research agenda for an in-depth understanding of the interactions between vegetation and flow is also highlighted.

Mitigating chromium toxicity in rice (Oryza sativa L.) via ABA and 6-BAP: Unveiling synergistic benefits on morphophysiological traits and ASA-GSH cycle

In recent years, the use of plant hormones, such as abscisic acid (ABA) and 6-benzylaminopurine (6-BAP), has gained significant attention for their role in mitigating abiotic stresses across various plant species. These hormones have been shown to play a vital role in enhancing the ascorbate-glutathione cycle and eliciting a wide range of plant growth and biomass, photosynthetic efficiency, oxidative stress and response of antioxidants and other physiological responses. While previous research has been conducted on the individual impact of ABA and 6-BAP in metal stress resistance among various crop species, their combined effects in the context of heavy metal-stressed conditions remain underexplored. The current investigation is to assess the beneficial effects of single and combined ABA (5 and 10 μM L−1) and 6-BAP (5 and 10 μM L−1) applications in rice (Oryza sativa L.) cultivated in chromium (Cr)-contaminated soil (100 μM). Our results showed that the Cr toxicity in the soil showed a significant declined in the growth, gas exchange attributes, sugars, AsA-GSH cycle, cellular fractionation, proline metabolism in O. sativa. However, Cr toxicity significantly increased oxidative stress biomarkers, organic acids, enzymatic and non-enzymatic antioxidants including their gene expression in O. sativa seedlings. Although, the application of ABA and 6-BAP showed a significant increase in the plant growth and biomass, gas exchange characteristics, enzymatic and non-enzymatic compounds and their gene expression and also decreased the oxidative stress,And Cr uptake. In addition, individual or combined application of ABA and 6-BAP enhanced the cellular fractionation and decreases the proline metabolism and AsA-GSH cycle in rice plants. These results open new insights for sustainable agriculture practices and hold immense promise in addressing the pressing challenges of heavy metal contamination in agricultural soils.

A Distributed Autonomous Mission Planning Method for the Low-Orbit Imaging Constellation

With the improvement of satellite autonomy, multi-satellite cooperative mission planning has become an important application. This requires multiple satellites to interact with each other via inter-satellite links to reach a consistent mission planning scheme. Considering issues such as inter-satellite link failure, external interference, and communication delay, algorithms should minimize communication costs as much as possible. The CBBA algorithm belongs to a fully distributed multi-agent task allocation algorithm, which has been introduced into multi-satellite autonomous task planning scenarios and achieved good planning results. This paper mainly focuses on the communication problem, and proposes an improved algorithm based on it, which is called c-CBBA. The algorithm is designed with task preemption strategy and single-chain strategy to reduce the communication volume. The task preemption strategy is an accelerated convergence mechanism designed for the convergence characteristics of CBBA, while the single-chain strategy is a communication link pruning strategy designed for the information exchange characteristics of satellites. Experiments in various scenarios show that the algorithm can effectively reduce communication volume while ensuring the effectiveness of task planning.

28-Homobrassinolide Primed Seed Improved Lead Stress Tolerance in Brassica rapa L. through Modulation of Physio-Biochemical Attributes and Nutrient Uptake.

Brassinosteroids (BRs) influence a variety of physiological reactions and alleviate different biotic and abiotic stressors. Turnip seedlings were grown with the goal of further exploring and expanding their function in plants under abiotic stress, particularly under heavy metal toxicity (lead stress). This study's objective was to ascertain the role of applied 28-homobrassinolide (HBL) in reducing lead (Pb) stress in turnip plants. Turnip seeds treated with 1, 5, and 10 µM HBL and were grown-up in Pb-contaminated soil (300 mg kg-1). Lead accumulation reduces biomass, growth attributes, and various biochemical parameters, as well as increasing proline content. Seed germination, root and shoot growth, and gas exchange characteristics were enhanced via HBL treatment. Furthermore, Pb-stressed seedlings had decreased total soluble protein concentrations, photosynthetic pigments, nutrition, and phenol content. Nonetheless, HBL increased chlorophyll a and chlorophyll b levels in plant, resulting in increased photosynthesis. As a result, seeds treated with HBL2 (5 µM L-1) had higher nutritional contents (Mg+2, Zn+2, Na+2, and K+1). HBL2-treated seedlings had higher DPPH and metal tolerance indexes. This led to the conclusion that HBL2 effectively reduced Pb toxicity and improved resistance in lead-contaminated soil.