Wall Conditions Research Articles

Guidelines for diagnosis and treatment of abdominal wall incision hernia (2024 edition)

Incisional hernia is a type of iatrogenic disease, and its clinical treatment is complicated. In recent years, there have been new advances in the diagnosis, surgical methods, and materials science of incisional hernias. On the basis of the Guidelines for diagnosis and treatment of abdominal wall incisional hernia (2018 edition), more than 70 experts and scholars over the country have discussed the consultation and modified the issues such as complex abdominal wall conditions, loss of domain, principles of incisional hernia treatment, techniques of abdominal wall hernia defects closure, perioperative management, and follow-up in this new edition, combined with evidence-based medical evaluation standards. The relevant medical institutions and peers in China are requested to carry out the actual clinical reference.

Reduction of Basic Iron Ore Sinter under Blast Furnace Wall and Center‐Simulated Conditions in CO–CO2–H2–H2O–N2 Gas

This study examines how varying conditions at the center and wall of a blast furnace (BF) impact the reduction of iron ore sinter in a gas containing hydrogen and water vapor. Sinter samples are isothermally reduced at 700–1100 °C using a BF simulator to assess reduction rates and extent. Characterization techniques analyze the reduced samples’ mineralogical, physical, and microstructural changes. Results indicate that metallic iron formed at 700 °C in samples reduced under BF center conditions but is absent up to 900 °C in BF wall conditions. Metallic iron is initially formed at the periphery and propagated inward as temperature increased. The sinter's non‐homogeneous structure hinders uniform gas diffusion, with unfused iron ore content obstructing reducibility. The skeletal density of reduced samples correlated with the degree of reduction. The reduction of magnetite to metallic iron through wüstite is observed. Wüstite reducibility was better than calcium ferrite. No carbon deposition is observed in all testing conditions. Comparisons to acid iron ore pellets suggest charging the sinter to the BF center and pellets to the wall, with a recommendation to minimize unfused iron ore in the sinter charge for improved reducibility.

Kinetic description of flow detachment at a smooth micro-step: the near-free-molecular regime

We study the pressure-driven steady gas flow, imposed by temperature or density gradients, over a backward-facing step in a two-dimensional microchannel. Focusing on the near-free-molecular regime of high Knudsen (Kn) numbers, the problem is analyzed asymptotically based on the Bhatnagar, Gross and Krook kinetic model, and supported by numerical Discrete Velocity Method and Direct Simulation Monte Carlo calculations. The wall conditions are formulated using the Maxwell model, superposing specular and diffuse surface conditions. The asymptotic solution contains the leading-order free-molecular description and a first-order integral representation of the near-free-molecular correction. Our results indicate that flow separation at the step can occur at arbitrarily large (yet finite) Knudsen numbers in channels with specular surfaces (i.e., having an accommodation coefficient of α=0), driven by temperature differences between the inlet and outlet reservoirs. It is then shown that detachment is significantly suppressed by density variations between reservoirs and partially diffuse surfaces (with α≳0.3). While the mass flow rate in a specular channel decreases with decreasing Kn≫1 in a density-driven setup (in line with the Knudsen Paradox), it increases in a temperature-driven flow. The results are obtained for arbitrary differences between the inlet and outlet reservoir equilibrium properties, and are rationalized using the linearized problem formulation.

ВЛИЯНИЕ ПРЕПАРАТА ОМНИК НА ИНТЕНСИВНОСТЬ КЛЕТОЧНЫХ РЕАКЦИЙ В ОЧАГЕ ЭКСПЕРИМЕНТАЛЬНОГО ВОСПАЛЕНИЯ

Relevance. The effect of the drug Omnic (Tamsulosin) reduces the tone of the smooth muscles of the prostate gland, bladder neck, prostatic part of the urethra, improves urine flow, reduces the symptoms of obstruction and irritation of the urinary tract in benign prostatic hypertrophy. However, there are no data on its anti-inflammatory effect. Objective. To determine the mechanisms of the anti-inflammatory effect of the drug Omnic on the model of purulent inflammation in rats. Material and methods. The study was conducted on 50 outbred white male rats divided into 2 series: Series 1 - control (they were implanted with diffusion chambers filled with an aqueous suspension of a one-day culture of staphylococcus aureus under the skin of the thigh; Series 2 - experimental (the animals of this series were modeled with purulent inflammation similar to the control, but from the 1st day of inflammation, the rats were injected intramuscularly with 0.02 ml of the Omnic preparation for 10 days). The materials were collected 2, 3, 5, 7, 10, 15, 20, 30, 60 days after implantation. The material was fixed in a 10 % solution of neutral formalin. In the peripheral zone of the inflammation focus, the state of the microvessels was qualitatively assessed, the concentration of mast cells, eosinophils, neutrophils, mononuclear cells and poorly differentiated fibroblasts was counted. Results. After 48 Hours after the onset of inflammation, a cellular wall with a thickness of 313.18 ± 30.19 μm is observed around the chamber wall. Three days after the introduction of the chambers, the thickness of the leukocyte wall remains the same and is 334.38 ± 25.69 μm. Five days after the onset of inflammation, the thickness of the leukocyte wall decreases sharply compared to the previous period and is 157.86 ± 46.08 μm. Seven days after the introduction of the chambers, the thickness of the cellular wall increases to 220 ± 29.67 μm. On the 10th day from the onset of inflammation, the thickness of the wall decreases to 129.52 ± 21.01 μm. On the 15th day of inflammation, the thickness and condition of the leukocyte wall do not change. On days 20-30-60 from the moment of implantation of the chambers, the remains of the leukocyte shaft with a thickness of 117.86 ± 29.6 μm were observed around them. Conclusion. The effect of Omnic on the dynamics of cellular reactions in the inflammation focus enhances the migration capacity of leukocytes, concentrates fibroblasts around the leukocyte shaft. At the same time, the synthesis of collagen by fibroblasts does not correspond to the thickness of the connective tissue capsule, which disrupts the maturation process of the capsule. Presumably, the action of Omnic is associated with the effect of the drug on the tone of capillaries and venules

Experimental study on metallic impurity behavior with boronization wall conditioning in EAST tokamak

Operation of EAST tokamak with full metal wall without any wall conditioning are attempted in 2023 and 2024 experimental campaign to address the issues related to ITER tungsten wall operation. It is found that H-mode plasma could be sustained even with a substantial increase in metallic impurity content caused by strong plasma-wall interaction under uncoated metal wall. Boronization wall conditioning is therefore performed to improve the plasma performance with higher injected power. This study aims to quantitatively assess the impact of boronization wall conditioning on metallic impurity concentration and behavior in the EAST tokamak. It is then proved to be an effective wall conditioning approach for significantly controlling high-Z impurity content. In this work, the impurity spectra at extreme ultraviolet (EUV) wavelength range measured by sets of fast-time-response and space-resolved EUV spectrometers are widely used in the data analysis. The variation in the boron content in plasma after boronization are investigated by monitoring the 2nd order of B V line at 48.59 Å. It is found that the persistence time of boron in EAST device after a boronization with 10 g of carborane (C2B10H12) is about 2000 s (∼150 shots) of discharge duration. The impact of different wall conditions (uncoated metal wall and boron coated wall) on metallic impurity content are then quantitatively studied. After boronization, the concentration of tungsten (CW) and molybdenum (CMo) dropped by 85 %, e. g., from 2.0 × 10-4 to 4.1 × 10-5 and from 4.6 × 10-5 to 6.3 × 10-6, respectively. While the concentration of copper (CCu) and iron (CFe) decreased by approximately 50 % and 65 %, respectively, e. g., from 4.3 × 10-5 to 2.1 × 10-5 and from 2.0 × 10-4 to 6.9 × 10-5. A comparison of the line emission profiles from tungsten ions of W26+ − W32+ and W43+ before and after boronization reveals an overall reduction in the intensity while without obvious change in the profile shape, which suggests a reduction in metallic impurities source after boronization instead of altering impurity transport in core plasma significantly.

Initial design concepts for solid boron injection in ITER

As part of ITER’s consideration to change its first wall material from beryllium to tungsten, the ITER Organization has proposed studying the feasibility of real-time solid boron injection (SBI) into the plasma to coat the walls and divertor to supplement glow discharge boronization (GDB) [1]. Boron deposits getter oxygen and reduce sputtering of tungsten from plasma facing components (PFCs). Particularly in areas with significant plasma wall interactions, boron coatings are expected to be short-lived under high performance plasma conditions. The proposed SBI system aims to maintain boron layers in these areas to avoid excessive radiation from tungsten in the plasma as a risk mitigation to ensure ITER will be able to reach and sustain Q = 10 conditions. The system will be used sparingly, as redeposition of boron can lead to significant tritium retention, which must be minimized in ITER to comply with nuclear safety concerns. SBI is proposed to limit and precisely control the amount of boron injected in real-time during plasma operation. Here, some of the design requirements and initial concepts for an SBI system in ITER are presented based on previous results carried out with SBI systems on a number of tokamaks and stellarators around the world [2–18].Previous results using SBI systems installed by PPPL have injected boron particles from 5 µm–2 mm diameter at calibrated rates of 2–200 mg/s in real-time during plasma operation on AUG [4], DIII-D [5], EAST [6], KSTAR [7], LHD [8], TFTR [9], WEST [10], and W7-X [11,12], leading to improved wall conditions with reduced plasma impurity concentrations and radiated power and improved plasma performance. The boron is ionized in the plasma edge and then deposited on plasma-wetted surfaces. On AUG [4], EAST [6] and WEST [10] reduced tungsten sputtering sources were observed following several discharges with SBI. Extrapolation of these SBI results are presented to estimate the amount of boron needed for wall conditioning in ITER. Real-time SBI control requirements and plasma operation scenarios for ITER are also described.

Energy-minimized mobilization of trapped non-aqueous phase liquids ganglia in three-dimensional biconical pores: Insights from surface evolver simulations

The mobilization of a ganglion is of great significance in various domains, including soil contamination. For effective soil remediation, it is essential to correctly characterize the behavior of trapped nonaqueous phase liquids (NAPLs). Therefore, in this study, a biconical pore structure is employed to investigate the conditions of mobilization of a trapped NAPL ganglion using Surface Evolver software. The results showed that in the three-dimensional model, the ganglion can take a sequence of saddle-shapes of increasingly negative mean curvature as it approaches the middle of the pore, and depending on the contact angle, it can cross the bulge through two main mechanisms: an asymmetric jump and an asymmetric crawl. These behaviors are triggered by the fact that the ganglion seeks the path of low energy. The pressure difference is observed to decrease with pore occupancy (from n = 2 to n = 2.5) and then increase (to n = 2.75). The same behavior occurs for pore occupancy n + 1; thus, pore occupancy plays a significant role only within a single pore. For a ganglion occupying the whole pore, the critical pressure is symmetric about the neutral wettability, namely, θ = 90°. For the pores partially occupied by the ganglion, the wettability condition of the pore wall can favor ganglion mobilization depending on pore occupancy. Furthermore, the contact angle hysteresis leads to a considerable increase in resistance to ganglion mobilization. These insights provide a deeper understanding of the pore-scale dynamics involved in NAPL mobilization, informing the design of more effective remediation strategies.

Intelligent characterization and robustness quantification of frozen soil strength images using a multi-module fusion strategy

In frozen wall engineering, traditional detection methods are difficult to implement for real-time monitoring of strength parameters, due to their intermittent nature. This makes it difficult to provide timely warnings and effective responses to potential risks of frozen walls, highlighting the urgent need for a method that can continuously and accurately monitor the strength of frozen walls. An image data-driven intelligent identification method for frozen soil strength based on convolutional neural networks is proposed. By capturing images of cured samples from multiple angles and conducting uniaxial compressive strength tests, the collected strength data were divided into 12 categories, creating an image dataset for deep learning model training. A Resnet-34 deep learning model combined with global attention and downsampling showed excellent performance in comparison with a series of basic models, with an accuracy of 93.3 % and no overfitting. The accuracy of the deep learning model was assessed using adversarial attack and defense strategies, serving as an indicator of robustness. The improved model exhibited better robustness in comparative analyses. Using SHapley Additive exPlanations (SHAP) value analysis, the feature extraction process of the convolutional neural network in recognizing frozen soil strength was investigated and clarified, confirming the model's ability to identify and extract key features in frozen soil images, such as particle size, texture, cracks, and ice crystal distribution patterns. This technology offers a cutting-edge method for real-time tracking of frozen wall conditions and early disaster warnings, significantly enhancing the safety and success rate of construction projects under freezing conditions.

Self-propulsion of a Quincke droplet under complex wall conditions

Self-propulsion of a Quincke droplet under complex wall conditions

Numerical Analysis of Spatial Distribution of Carbon in Methane Dry Reforming over Supported Nickel Catalyst in a Packed Bed Reactor

This study investigates carbon deposition during methane dry reforming over a nickel-based catalyst supported on alumina in a laboratory-scale fixed-bed reactor. Approximately 23.75 grams of catalyst were used, and simulations were performed using COMSOL 6.2 software. The reactor was simulated at isothermal wall conditions at four temperatures (650°C, 750°C, 850°C, and 950°C), with an equimolar CH₄ to CO₂ ratio in the feed. The results showed that while localized carbon deposition density increased with temperature, likely due to a higher local methane decomposition rate, the total amount of carbon deposited was inversely proportional to temperature. This suggests enhanced carbon gasification at higher temperatures. The total carbon deposited was estimated to be around 18 grams after 10,000 seconds of Time on Stream (TOS) at 650°C. As the temperature increased, the total carbon deposition decreased, although this reduction became negligible beyond 850°C. Furthermore, the hydrogen to carbon monoxide (H₂/CO) molar ratio peaked at over 1.1 at 650°C, dropped to approximately 0.76 at 750°C, and then rose back to 0.97 at 950°C. Steady-state operation was not achieved due to continuous carbon deposition and accumulation in the reactor. However, in the absence of carbon deposition, steady-state was reached around 100 seconds after the feed entered, at a velocity of 3 cm/s. Methane conversion reached 97% at 950°C.

Effect of electrical field on pulsation characteristics of laser-induced cavitation bubble

An experimental platform for laser-induced cavitation under the action of an electric field was built, and the bubble pulsation under two different conditions of infinite domain and solid wall was experimentally studied. The effects of voltage, laser energy, and liquid viscosity on bubble pulsation and the difference in the effect of voltage on bubble induced by different laser energies and bubble pulsation in different viscous liquids were explored. It is found that the size, velocity and period of bubble pulsation in infinite domain increase with the increase of laser energy, and the law is similar at the solid wall. When the voltage is applied, the size and period of bubble pulsation in infinite domain decrease with the increase of voltage, the bubble expansion speed decreases with the increase of voltage, but the bubble collapse speed increases with the increase of voltage. The diameter and velocity of bubble pulsation in infinite domain decrease with the increase of liquid viscosity, while the whole pulsation period of bubble increases with the increase of viscosity. Due to the damping effect of liquid, the effect of electric field on the bubble pulsation with higher viscosity is low.

Post-mortem analysis of material deposition and fuel retention on the plasma-facing materials after the 2021 campaign in EAST

Plasma-wall interaction (PWI) is a critical concern in tokamaks because of its significant impact on the lifetimes of plasma-facing materials (PFMs), fuel retention, and plasma performance. In 2020, the Experimental Advanced Superconducting Tokamak (EAST) PFMs were upgraded to predominantly metallic walls. Following the 2021 experimental campaign, the deposition distribution and fuel retention on the surfaces of the PFMs along both the poloidal and toroidal directions were analyzed. The poloidal tests commenced at the high-field side (HFS), proceeded to the lower divertor, then to the low-field side (LFS), and finally to the upper divertor. The toroidal tests were performed at the midplane of the HFS, beginning from port A and ending at port P. The distributions of the deposits in the poloidal and toroidal directions were clearly asymmetrical. Mo and Fe particles sputtered from the first wall and inner stainless steel (SS) components were prone to deposition in the lower divertor region, as evidenced by the fact that the elemental content in the far-SOL region of the inner divertor exhibited Mo and Fe peaks, as did both the near- and far-SOL regions of the outer divertor. In addition, quick re-deposition of W and Fe was observed, as demonstrated by the fact that their contents near the erosion sources were higher than those farther away along the toroidal first wall on the HFS. This tendency was stronger for W than for Fe. Further analysis indicated that the deposits consisted of Li, C, O, W, Mo, Fe, Cu, and Ni. The Li and Fe contents were much higher than those of other metal impurities, with peak values of 8.17 μg/mm2 and 7.78 μg/mm2, respectively. The Li content decreased along the HFS first wall from 8.17 μg/mm2 at P-2 to 1.82 μg/mm2 at P-22, and then increased to 2.72 μg/mm2 at P-32 in the divertor, while the Fe content was higher around the top side and the midplane of the HFS. The deposited Li originated from routine wall conditioning and existed primarily in the form of Li2CO3. Additionally, other metal impurities deposited on the Li2CO3 surfaces exhibited various irregular shapes, often appearing as aggregated and recrystallized small particles. Furthermore, significant deuterium (D) retention on the order of 1021 atoms/m2 was measured on all the analyzed SiC-coated graphite tiles on the HFS. The D content at location P-10 at the midplane was the highest along the poloidal direction of the HFS because it was directly facing the NBI beam.

Experimental, modeling, and numerical simulation of ultrasonic assisted drilling of CFRP/Ti stacks

Carbon fiber reinforced polymer (CFRP) and Ti-6Al-4V alloy (Ti) stacks structures are increasingly utilized in aircraft load-bearing applications, where the quality of hole processing significantly impacts their connection performance. Conventional drilling (CD) methods for CFRP/Ti stacks often encounter challenges such as severe interface damage, high cutting forces, and excessive heat generation. This study investigates the application of ultrasonic-assisted drilling (UAD) on CFRP/Ti stacks by integrating finite element method (FEM) modeling with experimental approaches to analyze the machinability of these materials under different machining methods and parameters. A self-developed high-frequency vibration spindle was employed to process CFRP/Ti stacks using both CD and UAD techniques. The newly developed numerical model effectively elucidates the mechanical and thermal coupling involved in the machining process and the transfer behavior of temperature and stress at the laminate interface. The experimental results of cutting force, hole inlet and outlet surface morphology, inner wall condition, chips, tool wear, etc. under different machining parameters were studied and analyzed. To ensure the reliability of our findings, experimental data were validated against simulation results. The findings reveal that UAD, when optimal separation conditions are achieved, significantly reduces cutting forces and enhances the surface morphology of both the inner and outer hole surfaces. Specifically, UAD lowers cutting forces by 27.2 % and the damage coefficient (Fd) by 15.7 % compared to CD. Furthermore, the high-frequency vibration generated by UAD markedly extends tool life. The specially designed high-frequency vibration spindle successfully meets drilling requirements, thereby significantly improving the machining performance of CFRP/Ti stacks materials, and it provides a certain reference for practical industrial applications.

Study of spectral features and depth distributions of boron layers on tungsten substrates by ps-LIBS in a vacuum environment

Boronization is used in present-devices as wall condition technique due to its effectiveness in reducing oxygen and other impurities in the vessel as well as improving plasma performance. The technique is also currently under consideration as wall conditioning method for the proposed full-tungsten (W) wall of the International Thermonuclear Experimental Reactor (ITER). However, the impact of the deposited Boron (B) layer thickness, and its homogeneity after the boronization process is uncertain as well as knowledge about the layer lifetime and improved conditions. In this study, an approach of the picosecond-laser-induced breakdown spectroscopy (ps-LIBS) is investigated to analyze the depth distribution of B-films on W-substrates by using three optical spectrometers in a vacuum environment. The depth distribution of two types of B-films on W-substrates with the thicknesses of 130 nm and 260 nm were sequentially measured under different laser spot sizes (varying the laser fluence). The B-films on the W-substrates were made by magnetron sputtering to simulate the thin B layers during the boronization. The measured average ablation rate of ps-LIBS shows a notable decrease with increasing laser spot size. Additionally, the spectral lines of B and W exhibit distinct intensity distributions under different spot sizes due to the different excitation thresholds of the B-films and the W-substrates. The interface between B-films and W-substrates, as well as the thickness of the B-films, were determined using the normalized intensity and intensity ratio method, respectively. The results from ps-LIBS measurements regarding the depth are in good agreement with those obtained through the Focused Ion Beam combined with Scanning Electron Microscopy (FIB-SEM) and Energy Dispersive X-ray Spectroscopy (EDS). These initial findings verify the feasibility to characterize the thickness and uniformity of thin B films in the order of 100 nm and below on W-substrates using ps-LIBS.

Impact of thermal column wall conditions and subcooled reflux on separation performance in miniplant distillation columns

Although experimental assessments of separation performance of structured packings in laboratory and miniplant distillation columns are common, the impact of the thermal boundary conditions of the column wall and highly subcooled reflux on fluid dynamics and separation performance has received little attention. With the aim of achieving scale-up capable separation performance results on a miniplant scale, this study investigates a 50 mm inner diameter heat jacketed distillation column. These results at constant gas load show thermal conditions can cause up to a 19 % change in separation performance, with subcooled walls and condensation effects enhancing it up to 12 %, and superheated walls reducing it by up to 7 %. High subcooling of the reflux led to minor, not significant losses in separation performance. The differential pressure remained unaffected at subcooled reflux and at varying thermal wall conditions. In contrast, an influence on the differential pressure in the counterflow was observed at subcooled wall conditions and low gas loads. These findings emphasize the importance of thermal boundary conditions in distillation performance measurements. In particular, they highlight the impact of mass transfer and fluid dynamics resulting from condensate wall flows induced by heat losses in miniplant column scale.

Automated geotechnical logging of core box images using machine learning

ABSTRACT Geotechnical characterization is contingent on reliable data to reduce uncertainty in the conditions of slope walls or underground workings. However, geotechnical data for greenfield and brownfield sites are often limited. The data that are available are often inconsistent and difficult to reliably use to inform the geotechnical domain model. SRK has developed machine learning workflows using deep learning for geotechnical classification of existing core box photographs to provide a reliable and objective data set that can be used to inform rock mass characterization and structural modeling. Conventional geotechnical parameters are often unsuitable for automation due to the reliance on subjective decisions by the logger for interval lengths or defining naturally open versus closed breaks. Three classification systems have been developed: the Core Damage Index (CDI), the Pseudo-RQD, and the Break Frequency. The CDI classifies discrete intervals within the photographs according to the average clast sizes relative to the core diameter to provide a high-resolution view of the variability of damage down a drill hole. Pseudo-RQD and Break Frequency are calculated by mapping the breaks and rubble zones observed on drill core images.

Removal of deuterium retention by various helium discharge cleanings under strong magnetic field in EAST superconducting tokamak

Fuel (deuterium) removal by various helium (He) discharge cleanings under strong magnetic field are studied in EAST superconducting tokamak, including deuterium-to-helium changeover by main plasma operation, glow discharge cleaning (GDC), and ion cyclotron wall conditioning (ICWC). The study demonstrates that He-GDC works well in strong magnetic field, but the cleaning is poloidally located near the GDC anodes. Both He-GDC and He-ICWC are effective in removing deuterium under strong magnetic field. Moreover, deuterium-to-helium changeover by main plasma operation is highly effective in rapidly reducing the deuterium from the first wall surface. A comprehensive comparison of the three techniques shows that deuterium-to-helium changeover and He-GDC exhibit higher deuterium removal rate, and the pulse duration and duty cycle of He-ICWC should be optimized to improve the deuterium removal. These studies present a comprehensive investigation on fuel removal techniques in EAST tokamak, providing valuable insights into the optimization of tritium removal strategies for future fusion reactors.

A Hydraulic Gradient and Stress-Controlled Erosion Apparatus for Assessing Soil Internal Erosion

Abstract Among the four dominant mechanisms of internal erosion, suffusion appears as one of the most complex. It is indeed the result of the combination of three processes: dislodgement of fine particles, transport of them, and filtration of some fluidized fine particles. These processes depend on the soil’s stress state and on the hydraulic gradient path. Thus, to ensure the repeatability of the suffusion test and to study with accuracy the influence of the aforementioned parameters, a new apparatus was developed. This apparatus is designed to test specimens under a vertical downward flow in hydraulic gradient controlled condition while controlling the confining pressure and the stress deviator, which can be either positive or negative. Ten tests on one cohesionless soil were performed in triaxial conditions, with the same mean effective stress and four different values of stress deviator. To compare with conventional suffusion results, one test is also performed in rigid wall conditions. For all performed tests, the same hydraulic gradient path was applied and particular attention is paid to the repeatability, which implies control of each test step. At the end of each test, the specimen was divided into four layers to measure post-suffusion grain size distributions. The time evolutions of the hydraulic conductivity and the erosion rate permit to identify four different phases. Each phase is characterized by two methods: one based on the hydraulic gradient and the second based on the expended energy by the fluid. The results show the great influence on the suffusion kinetics of the preferential flow paths, which localize in the body of the specimen in triaxial conditions and on the circumference in rigid wall ones. Under a constant mean effective stress, the effect of the stress deviator on the suffusion kinetics appears limited, for the tested soil and shear stress ratios.

Analytical investigation of porous medium effects on the flow of two micropolar fluids in a rotating annulus

Fluids with microstructures and microinertia play a vital role in microfluidics and nanfluidics system. One of such significant fluid is micropolar fluid. The characteristic behavior of micropolar fluid flow in conduit/pipe, etc. filled with porous medium helps us understand the flow behavior of biological fluids in porous media, groundwater flow in aquifiers, rotatory machines or viscometer. To understand such real-world problems, it is necessary to get into the mathematical model of such flow models. One such model with wide number of application is presented in this paper. This work investigated the flow of two micropolar fluids between the region formed by two concentric cylinders. Authors have considered inner cylinder to be at rest and outer cylinder rotating at a constant angular velocity. The region between two concentric cylinder is filled with an isotropic porous material. A slip condition at the outer wall and continuity conditions at interface of two fluids has been utilized to obtain an analytical solution for the proposed model. The numerical solution of the obtained solution for present problem is used to graphically analyze the motion of immisicble micropolar fluids rotating in an annulus filled with the porous medium. It is found that an outer cylinder has a notable influence on the flow behavior of immiscible micropolar fluids, contrary to the effect observed within the inner region. An analytical approach of this work not only helps us obtain precise results and analysis of the flow, but it also serves as a useful validation for future approximations within the scope of this work.

Properties of boron layers deposited during boronisations in W7-X

Boronisation was first used for wall conditioning in W7-X during the OP 1.2b operational period, which was characterized by the use of the fine-grain graphite Test Divertor Unit (TDU) and inertial cooling only. After this period, deposited layers were observed on all inner surfaces. Deposited layers were analyzed on 21 inner wall tiles using ion beam analysis methods, the deposited layers consisted mostly of boron with additional carbon and oxygen. During the operational period OP2.1 with an actively water cooled divertor made of carbon fiber reinforced carbon, different materials were exposed during two individual boronisations using the multi-purpose manipulator. Deposited boronisation layers on the samples were analyzed using nuclear reaction analysis. The deposited layer thicknesses showed some variation depending on substrate material and surface roughness, but a systematic dependence on material and/or roughness was not observed. Under the typical boronisation conditions at W7-X, one A × h (Ampere times hour) of boronisation results in a boronisation layer with a thickness of about 30 ± 15 × 1015B-atoms/cm2 (about 3 ± 1.5 nm) at the position of the multi-purpose manipulator. The oxygen gettering capacity of the layers is up to 0.5 – 0.9O/B.