Saturable Process Research Articles

Microarc Molybdenum Steel Saturation Using Ammonium Molybdate

Introduction. One of the most significant challenges in modern materials science is increasing the reliability and durability of tools and machine parts. To address this issue, it is essential to develop high-hardness coatings with enhanced properties. Typically, high-energy techniques are employed for this purpose, but they require complex and costly equipment, limiting their widespread use. Therefore, problem of creating such coatings remains a significant challenge. An effective and affordable approach to creating these coatings on steel products is microarc surface alloying from a coating pre-applied to the surface of the hardened products. The aim of the work was to assess the potential of diffusion molybdenum saturation for creating such coatings. Ammonium molybdate was used as the diffusant agent.Materials and Methods. To achieve the aim of this study, we used thermodynamic analysis of chemical reactions that can occur within the temperature range of the microarc heating process. For each reaction, we calculated the change in standard Gibbs energy, which allowed us to determine the feasibility and range of occurrence. An experimental study of the microarc molybdenum saturation process was conducted using ammonium molybdate on steel 20 samples using a laboratory setup. The surface current density was set at 0.53 A/cm², and the duration of the process was 6 minutes.Results. The Gibbs free energy changes for chemical reactions that can occur during the thermal decomposition of ammonium molybdate have been calculated. An experimental study has shown the formation of a molybdenum coating, and the concentration of molybdenum in the diffusion layer has been determined. On the surface of the samples, carbides Mo2C and Fe3Mo3C have been found. The dependence of the coating depth on the content of diffusant in the coating and its thickness has been determined.Discussion and Conclusion. Thermodynamic analysis has shown that atomic molybdenum can be formed through direct reduction or with the intermediate formation of molybdenum dioxide. The research has confirmed the formation of a diffusion coating on steel after microarc saturation with molybdenum, and the depth of this coating depends on the amount of diffusant in the coating and its thickness. These findings will be used to develop technological processes for microarc molybdenum plating of steel products.

Pengaruh Kualitas Pelayanan dan Kualitas Produk terhadap Tingkat Kepuasan Pelanggan Grapari Telkomsel Branch Gorontalo

This research aims to determine the influence of service quality and product quality on the level of customer satisfaction of Grapari Telkomsel Branch Gorontalo partially or simultaneously. The approach in this research is quantitative with correlational methods. Data collection in this research was carried out using a questionnaire. The total sample was 210 people obtained by a saturated sampling process. Data analysis in this research is quantitative inferential multiple regression analysis. The research results show that (1) Service quality has a positive and significant effect on customer satisfaction at Grapari Telkomsel Branch Gorontalo with a partial coefficient of determination of 28.90%. (2) Product quality has a positive and significant effect on customer satisfaction at Grapari Telkomsel Branch Gorontalo with a partial coefficient of determination of 28.50%. (3) Service quality and product quality simultaneously have a significant effect on the level of Customer Satisfaction of Grapari Telkomsel Branch Gorontalo with a coefficient of determination of 57.40%. The remaining 42.60% is influenced by other variables not studied such as price, promotions and customer emotions. This shows that the better the quality of service and product quality, the benefits of increasing customer satisfaction will be more loyal to using Telkomsel.

Structure and properties of the boride layer of steel using the plasma alloying method

Boration is one of the promising methods for increasing surface hardness and wear resistance, resistance to oxidation and corrosion of mechanical engineering parts. The diffusion saturation process is characterized by a long duration, as well as a shallow depth of the hardened layer. The use of concentrated heating sources can solve these problems. Among the methods of high-energy exposure, the technology of plasma surface alloying should be highlighted. In this paper, the study of the microstructure and properties of the boride layer obtained on steel by plasma alloying is carried out. It is noted that the boron-doped layer has a heterogeneous structure and high hardness. It is noted that the layer obtained after alloying with a current of 120 A has the highest microhardness value and amounts to 859–1265 HV. With an increase in current to 140 A, the microhardness of the alloyed layer decreases and amounts to 761–1048 HV. Increasing the current to 160 A leads to a significant decrease in the microhardness of the surface layer and it is 452–747 HV. It is known that the volume of iron boride fractions determines the degree of hardening of the steel surface. An increase in the plasma arc current leads to a decrease in the proportion of primary borides in the surface layer after alloying, and therefore leads to a decrease in microhardness. The alloyed layer has characteristic zones: hypereutectic, eutectic and hypoeutectic. An increase in current leads to a significant change in the microstructure of the surface layer and a decrease in the microhardness of the alloyed layer. The surface layer after plasma alloying with a current of 120 A has the highest microhardness (1265 HV). It has been established that it is possible to obtain a boride layer using the technology of plasma surface doping with boron. After processing, the alloyed layer is characterized by a heterogeneous structure and has high hardness.

Understanding Voriconazole Metabolism: A Middle-Out Physiologically-Based Pharmacokinetic Modelling Framework Integrating In Vitro and Clinical Insights.

Voriconazole (VRC), a broad-spectrum antifungal drug, exhibits nonlinear pharmacokinetics (PK) due to saturable metabolic processes, autoinhibition and metabolite-mediated inhibition on their own formation. VRC PK is also characterised by high inter- and intraindividual variability, primarily associated with cytochrome P450 (CYP)2C19 genetic polymorphism. Additionally, recent in vitro findings indicate that VRC main metabolites, voriconazole N-oxide (NO) and hydroxyvoriconazole (OHVRC), inhibit CYP enzymes responsible for VRC metabolism, adding to its PK variability. This variability poses a significant risk of therapeutic failure or adverse events, which are major challenges in VRC therapy. Understanding the underlying processes and sources of these variabilities is essentialfor safe and effective therapy. This work aimed to develop a whole-body physiologically-based pharmacokinetic (PBPK) modelling framework that elucidates the complex metabolism of VRC and the impact of its metabolites, NO and OHVRC, on the PK of the parent, leveraging both in vitro and in vivo clinical data in a middle-out approach. A coupled parent-metabolite PBPK model for VRC, NO and OHVRC was developed in a stepwise manner using PK-Sim® and MoBi®. Based on available in vitro data, NO formation was assumed to be mediated by CYP2C19, CYP3A4, and CYP2C9, while OHVRC formation was attributed solely to CYP3A4. Both metabolites were assumed to be excreted via renal clearance, with hepatic elimination also considered for NO. Inhibition functions were implemented to describe the complex interaction network of VRC autoinhibition and metabolite-mediated inhibition on each CYP enzyme. Using a combined bottom-up and middle-out approach, incorporating data from multiple clinical studies and existing literature, the model accurately predicted plasma concentration-time profiles across various intravenous dosing regimens in healthy adults, of different CYP2C19 genotype-predicted phenotypes. All (100%) of the predicted area under the concentration-time curve (AUC) and 94% of maximum concentration (Cmax) values of VRC met the 1.25-fold acceptance criterion, with overall absolute average fold errors of 1.12 and 1.14, respectively. Furthermore, all predicted AUC and Cmax values of NO and OHVRC met the twofold acceptance criterion. This comprehensive parent-metabolite PBPK model of VRC quantitatively elucidated the complex metabolism of the drug and emphasised the substantial impact of the primary metabolites on VRC PK. The comprehensive approachcombining bottom-up and middle-out modelling, therebyaccounting for VRC autoinhibition, metabolite-mediated inhibition, and the impact of CYP2C19 genetic polymorphisms, enhances our understanding of VRC PK. Moreover, the model can be pivotal in designing further in vitro experiments, ultimately allowing for extrapolation to paediatric populations, enhance treatment individualisation and improve clinical outcomes.

A device to generate multi-concentration tritiated water vapor

Access to a gas tritium source with controlled concentrations is the key to calibrating tritium measurement instruments. In this study, a method of generating multi-concentration tritiated water vapor based on a closed circulation loop is outlined. The method produces tritiated water vapor by a bubbling process, the operational parameters for achieving the saturated bubbling process were determined through simulation. The temperature dependence of the isotope fractionation coefficient has been established through experimental tests. In order to avoid leakage of tritium and contamination of laboratory environment, tritiated water vapor generator was plugged into a closed loop and tested. Two tritiated water standard samples with known concentrations were used to produce 20 tritiated water vapor samples at 10 different temperatures, where the experimental results were in good agreement with the empirical formula. Based on the experimental results, the model for a non-closed loop tritiated water vapor generation has been modified, and the formula for multi-concentration tritiated water vapor generation based on a closed loop is established.

ВІДНОВЛЕННЯ ПАЛАДІЄВИХ МЕМБРАН ПІСЛЯ КОНТАКТУ З ВОД-НЕМ ДЛЯ ВОДНЕВО-КИСНЕВИХ ПАЛИВНИХ ЕЛЕМЕНТІВ

Annotation. Studying the deformations of palladium membranes under the influence of hydrogen, which is a relevant issue for hydrogen energy and the nuclear industry. The mechanisms of palladium membrane shape change due to hydrogen penetration and the formation of temporary gradient alloys such as α-PdHn are consid-ered. Experiments were conducted using a hydrogen-vacuum installation, where the processes of membrane satu-ration and degassing were studied at temperatures from 100°C to 360°C and hydrogen pressures from 0.01 MPa to 2.5 MPa. It was established that the change in the shape of the membrane occurs in two stages: first, a rapid bending of the membrane is observed, and then a gradual return to the initial state. It was established that the maximum change in the shape of the membrane, which occurs at a constant temperature, depends on the diffu-sion coefficient and the equilibrium solubility of hydrogen in palladium. However, when the temperature chang-es, the diffusion coefficient of hydrogen in palladium and the equilibrium concentration of hydrogen in palladi-um also change, which affects the temperature dependence of the final shape change of the membrane. This fact makes it possible to effectively determine the time of hydrogen penetration into the membrane, control the change in shape and adjust the operating modes of the fuel cell. Special attention is paid to the use of palladium alloys with copper and silver to increase the resistance of membranes to the influence of hydrogen. It is shown that such alloys have better mechanical characteristics and a longer service life at high temperatures. The effect of degassing on the restoration of membranes after contact with hydrogen was studied, the main factors affecting the efficiency of this process were determined. The results of the work confirm the need for further research on increasing the resistance of palladium membranes to deformations, as well as the development of new materials and technologies to improve their operational characteristics

Violent Victimization in Emerging Adulthood and Its Longitudinal Impacts on Well-Being: A Study of Ever-Homeless Persons.

Persons who have experienced homelessness have higher lifetime risks of violent victimization relative to the general population. However, the long-term impacts of violent victimization on various facets of well-being are poorly understood among ever-homeless persons, particularly when violence is experienced in early adulthood. Here, using data from the National Longitudinal Study of Adolescent to Adult Health, we focus on a subsample of emerging adults who reported ever suffering homelessness (N = 481). Drawing primarily from Waves III and IV of the data, a series of regression models are specified to determine whether violent victimization in emerging adulthood is related to a range of negative outcomes later in life among ever-homeless persons (economic hardship, binge drinking, drug use, depression, offending, and victimization). Results indicate that victimization in emerging adulthood increases the risks for subsequent victimization for ever-homeless persons, but that it has no robust associations with any other outcomes examined. We explain these findings through processes of disadvantage saturation, in which the consequences of victimization may be more subdued among individuals who experience an array of hardships and disadvantages in their lives. The implications of these findings for policy are future research are discussed, and we emphasize the need for a context-contingent approach to the study of victimization and its life course consequences.

The economophysical model of the propagation of innovation: the Ising model

The process of technical and economic justification of investment, analysis and evaluation of the effectiveness of innovation requires a tool for describing and modeling the process of distribution of technology in the industry. The work presents a model of propagation of innovation involving physical approaches, describing the market saturation point, i.e. the point at which the exponential growth of the innovation propagation speed is replaced by the logarithmic growth. The object of the study is the propagation of innovation, and the subject is the development of the market saturation point functional. The authors justified the implementation and described the approach to modeling of the process of saturation of the market with innovation by the physical Ising model. The value of the Ising model’s toolkit is presented by the Curie point in ferromagnets which characterizes the second order phase transition. The article presents the mathematical model of the compliance of physical parameters with economic ones: the amount of inter-company influence, barriers to implementation and breakthrough of innovation. The authors adduce the discussion of the limitations and applicability of this model as well as further potential directions of study of economophysical models. The tools developed by the authors can be used in all sectors of economics to improve their innovation activity level.

Particle Simulation Study of Obliquely Propagating Whistler Waves in Low‐Beta Plasmas

AbstractWhistler mode waves, which are electromagnetic emissions commonly observed in various space plasma environments, play critical roles in electron dynamics. While most whistler waves are driven by temperature anisotropy and propagate parallel to the background magnetic field, these waves can also be excited in the oblique direction when electron plasma beta is very low (<0.025). Although linear theory accounts for the excitation processes of obliquely propagating whistler waves, the subsequent evolution and saturation processes remain inadequately understood. This study utilizes two‐dimensional self‐consistent simulations to investigate the complete wave‐particle interaction process. By scanning a broad parameter range, we derive scaling laws for the wave intensity, linking the wave properties to initial and final plasma conditions. The saturated temperature anisotropy from simulations can explain the upper bound anisotropy constraint observed by spacecraft well. Additional phase space analysis shows that both Landau and cyclotron resonance play critical roles in the evolution of electron velocity distribution, albeit in different energy ranges. Oblique whistler waves can effectively heat electrons through Landau resonance, creating a plateau distribution in the parallel direction. This research advances our understanding of the mechanisms behind obliquely propagating whistler waves in low‐beta plasmas and their impact on electron dynamics.

The Analysis of Differential Saturation in Shale Oil Accompanied by an Enhanced Classification of Fluid Distribution within the Pore

Shale oil saturated by high temperature (20 MPa) and high pressure (60 °C) conditions can not only realize the efficient saturation of shale, but also invert the shale oil return and drainage characteristics under the stratum temperature and pressure due to the heterogeneity of shale formations. In this study, the Chang 7 Member shale samples were collected, and the high-temperature and high-pressure containment device was utilized to saturate the shale oil efficiently under 20 MPa and 60 °C, and the differences of liquid hydrocarbon saturation and the degree of liquid hydrocarbon saturation for different types of pores and fractures in the shale were quantitatively characterized with a low-field nuclear magnetic resonance (NMR) technology. The results show that under the condition of formation temperature (60 °C) and pressure (20 MPa), shale oil saturation can be reached after 14 d of saturation in the shale samples. The shale oil saturation process can be roughly divided into three stages according to the various saturation rates: the rapid saturation stage, the slow saturation stage, and the second rapid saturation stage, and the degree of saturation of shale oil is characterized by a V-shape. The shale oil was distributed into four types of pore-fracture systems: adsorption pores, micropores, seepage fractures, and layer fractures. Additionally, the fluid dominantly distributes in the micropores and seepage fractures, the shale oil saturation degree of the micropores features a continuous increase, while that for the seepage fractures presents a V-shape, which finally determines the shale oil saturation characteristics of the shale.

Developments in Nanostructured MoS2-Decorated Reduced Graphene Oxide Composite Aerogel as an Electrocatalyst for the Hydrogen Evolution Reaction.

Developing lightweight, highly active surfaces with a high level of performance and great stability is crucial for ensuring the dependability of energy harvesting and conversion devices. Aerogel-based electrocatalysts are an efficient option for electrocatalytic hydrogen production because of their numerous benefits, such as their compatibility with interface engineering and their porous architecture. Herein, we report on the facile synthesis of a nanorod-like molybdenum sulfide-reduced graphene oxide (M-rG) aerogel as an electrocatalyst for the hydrogen evolution reaction (HER). The 3D architecture of the network-like structure of the M-rG hybrid aerogel was created via the hydrothermal technique, using a saturated NaCl solution-assisted process, where the MoS2 was homogeneously incorporated within the interconnected rGO aerogel. The optimized M-rG-300 aerogel electrocatalyst had a significantly decreased overpotential of 112 mV at 10 mA/cm2 for the HER in alkaline conditions. The M-rG-300 also showed a higher level of reliability. The remarkable efficiency of the HER involving the M-rG-300 is principally attributed to the excellent connectivity between the rGO and MoS2 in the aerogel structure. The efficient interconnection influenced the achievement of a larger electrochemically active surface area, increased electrical conductivity, and the exposure of more active sites for the HER. Furthermore, the creation of a synergistic effect in the M-rG-300 aerogel is the most probable mechanism to boost the electrocatalytic activity.

Low-frequency parametric amplification in saturable ytterbium-doped fibers at 1064 nm

Experimental results on parametric optical processes in saturable ytterbium-doped fibers (YDFs) at the wavelength of 1064 nm are reported. Significant photoinduced change of the refractive index under saturation of the fiber-optical absorption in the near-infrared range enables us to consider this medium as an effective optical Kerr (χ′′′) medium. For pumping, it needs continuous-wave Nd:YAG laser power of 10-mW scale, but the saturation process has the characteristic time ≤1ms, governed by the metastable level lifetime in YDF. We investigate the nearly degenerate collinear configuration of the optical parametric amplification (OPA). Here we focus on unidirectional transformation of the initial amplitude modulation in the incident pump wave to the output phase modulation as a manifestation of OPA in a narrowband case. This effect results from the conventional coupled-wave equations for the signal and idler waves—if one considers them as the modulation sidebands. It can also be treated as a result of the self-phase modulation of the periodically modulated pump in the Kerr medium. OPA gain of about 0.64 with the net gain ≈0.29 was experimentally estimated for the utilized 2-m-long YDF in the frequency band ≈200Hz.

Pore-scale probing CO2 huff-n-puff in extracting shale oil from different types of pores using online T1–T2 nuclear magnetic resonance spectroscopy

CO2 huff-n-puff shows great potential to promote shale oil recovery after primary depletion. However, the extracting process of shale oil residing in different types of pores induced by the injected CO2 remains unclear. Moreover, how to saturate shale core samples with oil is still an experimental challenge, and needs a recommended procedure. These issues significantly impede probing CO2 huff-n-puff in extracting shale oil as a means of enhanced oil recovery (EOR) processes. In this paper, the oil saturation process of shale core samples and their CO2 extraction response with respect to pore types were investigated using online T1–T2 nuclear magnetic resonance (NMR) spectroscopy. The results indicated that the oil saturation of shale core samples rapidly increased in the first 16 days under the conditions of 60 °C and 30 MPa and then tended to plateau. The maximum oil saturation could reach 46.2% after a vacuum and pressurization duration of 20 days. After saturation, three distinct regions were identified on the T1–T2 NMR spectra of the shale core samples, corresponding to kerogen, organic pores (OPs), and inorganic pores (IPs), respectively. The oil trapped in IPs was the primary target for CO2 huff-n-puff in shale with a maximum cumulative oil recovery (COR) of 70% original oil in place (OOIP) after three cycles, while the oil trapped in OPs and kerogen presented challenges for extraction (COR < 24.2% OOIP in OPs and almost none for kerogen). CO2 preferentially extracted the accessible oil trapped in large IPs, while due to the tiny pores and strong affinity of oil-wet walls, the oil saturated in OPs mainly existed in an adsorbed state, leading to an insignificant COR. Furthermore, COR demonstrated a linear increasing tendency with soaking pressure, even when the pressure noticeably exceeded the minimum miscible pressure, implying that the formation of a miscible phase between CO2 and oil was not the primary drive for CO2 huff-n-puff in shale.

Comparative Laboratory Wettability Study of Sandstone, Tuff, and Shale Using 12-MHz NMR T1-T2 Fluid Typing: Insight of Shale

Summary Wettability is a fundamental parameter significantly influencing fluid distributions, saturations, and relative permeability in porous media. Despite the availability of several wettability measurement techniques, obtaining consistent wettability index results, particularly in tight reservoirs, remains a challenge. Nevertheless, obtaining accurate wettability indices is crucial for gaining a more profound understanding of rock properties and precisely identifying and evaluating oil recovery processes. This study adapts T1-T2 nuclear magnetic resonance (NMR) in twin plugs (cores cut in half from the middle) style wettability measurement for different reservoirs. The fluid typing in different lithologies by T1-T2 NMR is proved to be effective by introducing D2O with a modified pressurization saturation process. Therefore, demarcating the regions requires multiple experiments, including sole brine, sole oil phase, and D2O imbibition processes, to define oil and water distribution regions. Such fluid typing ability enables better accuracy in wettability characterization. The weighing method shows good agreement with the T2 spectrum but lacks the ability to differentiate fluids. It is observed that the same fluid in various porous media displays different divisions of T1/T2 ratios. The wettability index of sandstone, tuff, and shale measured by weighing and T1-T2 NMR method are compared and studied to demonstrate the applicability of different methods. The weighing method and the NMR method, as modified-Amott methods, share the same fundamental principle but differ in their measurement techniques. This study’s T1-T2 NMR wettability indices are −0.52, 0.06, and 0.14, whereas the weighing wettability indices are −0.63, 0.07, and 0.34 of sandstone, tuff, and shale, respectively. In addition to the difference in shale wettability index, there are also differences in shale porosity measured by methods with/without the ability to differentiate the fluid types. The T1-T2 NMR method is more accurate in measuring the wettability of shale because it can distinguish among free water in pores, structural water, and clay-bound water in smectitic clay minerals. If the clay-related water is not treated properly, the hydrophilicity of the shale will be overestimated. Ultimately, four types of pores (water-wet, oil-wet, mixed-wet, and unconnected pores) are classified and quantified by the proposed NMR method.

Link interaction for K-terminal network cascading failures subject to saturating branching process

When improving a multi-component system reliability, we often replaced or maintained a component while ignoring the reliability of another component due to the budget cost constraint. Thus, the interaction effects regarding system reliability between two components should be analyzed. However, conventional research efforts concerning component interactions have two gaps: (i) they are unsuitable for systems with complex structures, such as K-terminal network (for short network), only pertaining to multi-component systems with simple structures; and (ii) they fail to consider component interactions in the context of cascading failure. To fill these gaps, this paper analyzes the effects of link interactions regarding network reliability in the context of link cascading failures. Under this context, we characterize the total number of link failures by a saturating branching process, based on which a network reliability model is established. According to the reliability model, we introduce the joint reliability importance (JRI) measure of two links to analyze link interactions. To evaluate the JRI, we derive several equations and construct a numerical algorithm from the theoretical and numerical standpoints, respectively. Theoretically, we find the conditions under which the scale and sign of the JRI is decided, so that the extent and type of interactions for two links can be analyzed. Numerically, an experiment is conducted to demonstrate how to apply JRI to evaluate link interactions in the circumstance of link cascading failures, which further confirms the theoretical analysis.

Assessment of molecularly imprinted polymers for selective removal of diclofenac from wastewater by laboratory and pilot-scale adsorption tests

This study investigated the potential of Molecularly Imprinted Polymers (MIPs) to integrate schemes for wastewater reuse and to serve as effective adsorbent for the removal of a target emerging contaminant (i.e., diclofenac – DCF), after or within pilot scale anaerobic biological treatments. Batch tests were performed to evaluate the effect on DCF removal during anaerobic biological processes by enriching activated sludge of an Upflow Anaerobic Sludge Blanket (UASB) reactor (TSS =19.6 g/L), and an Anaerobic Membrane Bioreactor (AnMBR) (TSS = 120 mg/L) reactors with MIPs (3 mg/L). Therefore, tertiary treatments were investigated by columns adsorption tests that were performed first at lab scale using DCF (15 mg/L) solution in deionized water, and then in-site by treating the anaerobic permeate effluent from the AnMBR at pilot scale level (DCF 500 μg/L). Clogging or blockage of the column bed was not observed during these field tests, where the saturation process of MIPs was slower compared to laboratory tests that used deionized water. In addition, the empirical Thomas Model, Yoon-Nelson Model, Dose-Response Model and Adam Bohart Model showed very good fittings with the experimental data obtained during experiments performed with both synthetic water and anaerobic effluents showing their suitability for the description of breakthrough curves. Finally, it was observed that after regeneration the MIPs can be efficiently reused since adsorption capacity is sufficiently preserved.

Entrained air and freeze-thaw durability of concrete incorporating nano-fibrillated cellulose (NFC)

NanoFibrillated Cellulose (NFC) has consistently proven effective at improving some key properties of cement-based materials. However, till date, the effects of the NFC on the freeze-thaw (F-T) durability of concrete has received little attention. This study aims to fill this gap by first evaluating the fresh, entrained air content of 0.65 and 0.40 water-cement ratio, Plain and Plain +0.1 % NFC concrete mixtures prepared with and without an Air Entrainment Admixture (AEA). Micro computed tomography scan (CT-Scan) was also utilized in investigating the effects of the NFC on the entrained air characteristics of hardened concrete specimens. Thereafter, water-saturation process, F-T durability via, changes in specimen mass, Relative Dynamic Modulus of Elasticity (RDME) were investigated, and strain accumulation was monitored until specimens failed or 300 F-T cycles were attained. Relative to Plain concrete mixtures, test results showed that entrained air content values of Plain +0.1 % NFC mixtures were lower, causing the effective void spacing to significantly increase. However, RDME and strain measurements indicated that F-T internal damage progression in NFC-modified concrete mixtures prepared without an AEA was considerably slower compared to corresponding Plain concrete mixtures. Moreover, the overall F-T performances of air-entrained, Plain and Plain +0.1 % NFC concrete specimens were comparable despite that the latter set of specimens had lower entrained air content, with wider entrained air void spacing. Besides impeding the saturation process of specimen, the NFC enhanced the strain capacity of concrete, and the significant contraction of specimen on exposure to cooling-temperatures was helpful in mitigating expansive F-T damage process. Therefore, for applications where strength reductions associated with air-entrained plain mixtures are undesirable, the NFC will be very beneficial for the production of high-strength and F-T durable concrete.

Improving the Efficiency and Environmental Friendliness of Urban Stormwater Management by Enhancing the Water Filtration Model in Rain Gardens

Rain gardens are used to solve urban problems related to the negative impact of stormwater. (1) Scientific contributions from different countries provide general guidelines for the design and operation of rain gardens in different geographical areas. Given the small spatial scale of rain gardens, the use of existing infiltration models often leads to design errors. (2) The purpose of this paper is to develop a hydrological model by introducing a system of equations that extends the ability to calculate the rate, flow rate and time of saturation of layers with moisture and rainwater leakage from the rain garden system. (3) The results obtained allow us to describe the dynamic processes of passage and saturation of layers of the rain garden at a certain point in time, which extends the ability to calculate the flow rate. It was established that the smaller the area of the rain garden compared to the area of the catchment basin, the faster it reaches its full saturation. Increasing the thickness of the rain garden layers allows for an increase in the efficiency of water retention at a lower value of the area ratio. (4) The practical significance of the results obtained is especially important for the correct description of hydrodynamics in the system and determining the optimal conditions for the effective functioning and management of the rain garden structure for any climatic region.

Dynamic characteristics of a coaxial magnetic switch modulating pulse forming networks.

Pulsed power generators utilizing magnetic switch technology within the 100ns scale have become widespread for surface treatment, high power microwave generation, and food processing, in which the dynamic characteristics of the magnetic switch perform an important function. The saturation process, electric field between layers, and energy loss are closely associated with the applied time scale of the magnetic core, which affects the dynamic characteristics of the switch. However, compared with the study within the microsecond scale, the dynamic characteristics of magnetic switches within the 100ns scale have not been studied in depth. In this paper, the dynamic characteristics of a coaxial magnetic switch modulating pulse forming networks (PFNs) are studied via both field-loop co-simulation and scaled experimental test. It is found that increasing PFN section number (Ns) leads to an acceleration in the saturation process of the core, which helps understand the switch performance of the magnetic core more clearly. With respect to a specific magnetic switch based on a ferromagnetic core, it is quantitatively analyzed that increasing Ns from 1 to 10 leads to a 16.1% reduction in core saturation time (tsat), a 13.4% increase in eddy loss (EET), and a 5.7% rise in maximum interlamination field strength (Emax) under the 100ns scale; however, tsat is reduced by 19.3%, EET increases by 5.2%, and Emax rises by 2.3% under the microsecond scale. The results could provide a design reference for magnetic switches in pulsed power generators.

Self Consistent Modeling of Relativistic Runaway Electron Beams Giving Rise to Terrestrial Gamma‐Rays Flashes

AbstractTerrestrial Gamma Ray Flashes (TGFs) are short bursts of gamma rays occurring during thunderstorms. They are believed to be produced by Relativistic Runaway Electron Avalanches (RREAs). In this paper, we present a new numerical model based on the Particle‐In‐Cell (PIC) method to simulate the interactions between the electromagnetic fields and the electron avalanche self‐consistently. The code uses a cylindrical Yee lattice to numerically solve the electromagnetic fields, a Monte Carlo approach to simulate collisions with air molecules, and a plasma fluid model to calculate the effects of low‐energy electrons and ions. The model is first tested through the reproduction of dispersion relations in a hot plasma. RREAs propagating under a homogeneous background electric field are then simulated. Owing to the self‐consistent nature of this description, we report here new physical properties such as saturation processes in the electron density and in the number of high‐energy electrons, detailed dynamical screening of the electric field in the ion trail of the avalanche, and the associated electric currents. We find that the saturation of RREAs is obtained when the numbers of high‐energy electrons and photons is consistent with those believed to be representative of TGF sources.