Model Investigation of Argon Injection into Liquid Steel at Ladle Furnace Station with Using of Innovative Module

High-quality steels are defined primarily by a small quantity of non-metallic inclusions and a high degree of chemical homogenisation. The ladle furnace (LF) is the most important metallurgical unit in which the quantity of non-metallic inclusions can be significantly reduced while ensuring metal chemical homogenisation. It is achieved largely due to appropriate controlling and the use of increasingly developed inert gas purging techniques. Various types of porous plugs (channel or radial type) are used in the metallurgical ladles. In aggregate units of intermediate-ladle type, various types of channel plugs and/or gas curtains are successfully used. In the research presented herein, a new and innovative module for inert gas injection into liquid steel for deep refining was tested. The presented research relates to the innovative module using to replace the standard porous plug in the steelmaking ladle on the outside-furnace (LF) processing station. Hybrid modelling methods (numerical and physical modelling) were used to carry out research. Module using causes significantly faster alloy additive dispersion in ladle volume compared with the standard solution (the standard porous plug). Furthermore, the obtained flowing structure positively affects liquid steel refining and mixing processes after alloy additive addition. A new technological solution, i.e., gas-injection module-differs from the traditional porous plugs currently used in the steel mills in terms of geometric parameters, external and internal structure, and what is most importantly, terms of the active surface area-shall be understood in as the surface area wherein slots occur.

Urban Versus Lake Impacts on Heat Stress and Its Disparities in a Shoreline City

Shoreline cities are influenced by both urban-scale processes and land-water interactions, with consequences on heat exposure and its disparities. Heat exposure studies over these cities have focused on air and skin temperature, even though moisture advection from water bodies can also modulate heat stress. Here, using an ensemble of model simulations covering Chicago, we find that Lake Michigan strongly reduces heat exposure (2.75°C reduction in maximum average air temperature in Chicago) and heat stress (maximum average wet bulb globe temperature reduced by 0.86°C) during the day, while urbanization enhances them at night (2.75 and 1.57°C increases in minimum average air and wet bulb globe temperature, respectively). We also demonstrate that urban and lake impacts on temperature (particularly skin temperature), including their extremes, and lake-to-land gradients, are stronger than the corresponding impacts on heat stress, partly due to humidity-related feedback. Likewise, environmental disparities across community areas in Chicago seen for skin temperature are much higher (1.29°C increase for maximum average values per $10,000 higher median income per capita) than disparities in air temperature (0.50°C increase) and wet bulb globe temperature (0.23°C increase). The results call for consistent use of physiologically relevant heat exposure metrics to accurately capture the public health implications of urbanization.

Electric field bridging-effect in electrified microfibrils' scaffolds

Introduction: The use of biocompatible scaffolds combined with the implantation of neural stem cells, is increasingly being investigated to promote the regeneration of damaged neural tissue, for instance, after a Spinal Cord Injury (SCI). In particular, aligned Polylactic Acid (PLA) microfibrils' scaffolds are capable of supporting cells, promoting their survival and guiding their differentiation in neural lineage to repair the lesion. Despite its biocompatible nature, PLA is an electrically insulating material and thus it could be detrimental for increasingly common scaffolds' electric functionalization, aimed at accelerating the cellular processes. In this context, the European RISEUP project aims to combine high intense microseconds pulses and DC stimulation with neurogenesis, supported by a PLA microfibrils' scaffold. Methods: In this paper a numerical study on the effect of microfibrils' scaffolds on the E-field distribution, in planar interdigitated electrodes, is presented. Realistic microfibrils' 3D CAD models have been built to carry out a numerical dosimetry study, through Comsol Multiphysics software. Results: Under a voltage of 10 V, microfibrils redistribute the E-field values focalizing the field streamlines in the spaces between the fibers, allowing the field to pass and reach maximum values up to 100 kV/m and values comparable with the bare electrodes' device (without fibers). Discussion: Globally the median E-field inside the scaffolded electrodes is the 90% of the nominal field, allowing an adequate cells' exposure.

[Effect of Carbon Dioxide Emission Reduction Policy on Air Quality Improvement in Jiangsu Province]

Carbon emission peaking and air quality improvement is an urgent issue in the research of the atmospheric environment. Here, the emission factor method was used to compile the city-level greenhouse gas emission inventory of Jiangsu Province from 2010 to 2019, which was then combined with greenhouse gas-air pollutant synergy analysis and WRF-Chem air quality model simulation to analyze the synergistic gain of air quality improvement under different carbon emission reduction scenarios. The results revealed that the annual mean CO2 emission in Jiangsu Province from 2010 to 2019 was 701.74-897.47 Mt. Suzhou, Xuzhou, and Nanjing had the highest emissions (91.19-182.12 Mt·a-1); Yangzhou, Suqian, and Lianyungang had the lowest emissions (13.19-32.54 Mt·a-1); and majority of the cities had a continuous upward trend in the CO2 emissions. Energy activities were the main source of CO2 emissions, accounting for nearly 90%, whereas industrial production processes contributed to the remaining 10%. This study designed three types of CO2 emission reduction conditions according to different emission reduction priorities, namely, sector-wide collaborative, energy priority, and industrial priority. Each type of emission reduction condition included a different intensity of CO2 emission reduction (10%, 20%, and 40%). The condition-based simulation results demonstrated that, taking 2017 as the base year, the average annual decrease in PM2.5 concentration in sector-wide collaborative, energy priority, and industrial priority emission reduction was 6.7-21.1, 3.1-12.0, and 3.4-14.3 μg·m-3, respectively. Sector-wide collaborative emission reduction had the most notable improvement in PM2.5 pollution. Under the condition of the sector-wide collaborative emission reduction of 40%, the average annual PM2.5 concentration of all cities, excluding Xuzhou and Suqian, met the national Ⅱ standard (35 μg·m-3). The change responses of PM10, SO2, NO2, and CO were similar to that of PM2.5, but O3 pollution increased under the conditions of energy and industrial priorities.

Numerical Model Validation of the Blood Flow through a Microchannel Hyperbolic Contraction

A computational fluid dynamics (CFD) model of blood flow through hyperbolic contraction with a discrete phase model (DPM) was experimentally validated. For this purpose, the positions and velocities of red blood cells (RBCs) flowing in a microchannel with hyperbolic contraction were experimentally assessed using image analysis techniques, and were subsequently compared with the numerical results. The numerically and experimentally obtained velocity fields were in good agreement, with errors smaller than 10%. Additionally, a nearly constant strain rate was observed in the contraction region, which can be attributed to the quasilinear increase in the velocity along the hyperbolic contraction. Therefore, the numerical technique used was validated due to the close similarity between the numerically and experimentally obtained results. The tested CFD model can be used to optimize the microchannel design by minimizing the need to fabricate prototypes and evaluate them experimentally.

The role of continuous glucose monitoring in physical activity and nutrition management: perspectives on present and possible uses

PURPOSE

Continuous glucose monitoring (CGM) is on the rise as the prevalence of obesity and diabetes increases. This review aimed to explore the use of CGM and its potential novel applications in physical activity and nutrition management.

METHODS

We searched PubMed, Web of Science, and Wiley Online Library databases using the keywords 'continuous glucose monitor,' 'nutrition,' 'physical activity,' and 'numerical modeling.'

RESULTS

Continuous blood glucose measurement is useful for individuals with obesity and diabetes. Long-term blood glucose data allow for personalized planning of nutritional composition, meal timing, and physical activity type and intensity, as well as help prevent hypoglycemia and hyperglycemia. Thus, understanding the limitations of CGM is important for its effective use.

CONCLUSION

CGM systems are being increasingly used to monitor and identify appropriate blood glucose controlling interventions. Blood glucose level is influenced by various factors such as nutrient composition, meal timing, physical activity, circadian rhythm, and cortisol levels. Numerical modeling can be used to analyze the complex relationship between stress, sleep, nutrition, and physical activity, which affect blood glucose levels. In future, blood glucose, sleep, and stress data will be integrated to predict appropriate lifestyle levels for blood glucose management. This integrated approach improves glucose control and overall wellbeing, potentially reducing societal costs.

Numerical Study on the Seismic Performance of Cold-Formed Steel Shear Walls with Steel Sheathing and Gypsum Board

The cold-formed steel shear wall with steel sheathing has gained increasing popularity due to its excellent shear capacity. To extend the applicability of this system to multi-story residences, aside from experimental investigations on the shear walls, it is essential to conduct a comprehensive study on the seismic performance of buildings. In this paper, numerical simulations were conducted on specimens subjected to monotonic and cyclic loading. Subsequently, seismic analysis of mid-rise building models was also carried out to investigate the influence of the proposed shear wall on building seismic performance. The research findings indicate that this study's modeling method can effectively simulate the shear performance of the proposed shear wall under monotonic and cyclic loading. In addition, the proposed shear wall significantly enhances the structural stiffness and improves the seismic performance of the structure under seismic action.

Locomotion characteristics of a wheeled vibration-driven robot with an enhanced pantograph-type suspension

Introduction: The paper considers the improved design of the wheeled vibration-driven robot equipped with an inertial exciter (unbalanced rotor) and enhanced pantograph-type suspension. The primary purpose and objectives of the study are focused on mathematical modeling, computer simulation, and experimental testing of locomotion conditions of the novel robot prototype. The primary scientific novelty of the present research consists in substantiating the possibilities of implementing the enhanced pantograph-type suspension in order to improve the robot's kinematic characteristics, particularly the average translational speed. Methods: The simplified dynamic diagram of the robot's oscillatory system is developed, and the mathematical model describing its locomotion conditions is derived using the Euler-Lagrange differential equations. The numerical modeling is carried out in the Mathematica software with the help of the Runge-Kutta methods. Computer simulation of the robot motion is performed in the SolidWorks Motion software using the variable step integration method (Gear's method). The experimental investigations of the robot prototype operating conditions are conducted at the Vibroengineering Laboratory of Lviv Polytechnic National University using the WitMotion accelerometers and software. The experimental data is processed in the MathCad software. Results and discussion: The obtained results show the time dependencies of the robot body's basic kinematic parameters (accelerations, velocities, displacements) under different operating conditions, particularly the angular frequencies of the unbalanced rotor. The numerical modeling, computer simulation, and experimental investigations present almost similar results: the smallest horizontal speed of about 1 mm/s is observed at the supplied voltage of 3.47 V when the forced frequency is equal to 500 rpm; the largest locomotion speed is approximately 40 mm/s at the supplied voltage of 10 V and forced frequency of 1,500 rpm. The paper may be interesting for designers and researchers of similar vibration-driven robotic systems based on wheeled chassis, and the results may be used while implementing the experimental and industrial prototypes of vibration-driven robots for various purposes, particularly, for inspecting and cleaning the pipelines. Further investigation on the subject of the paper should be focused on analyzing the relations between the power consumption, average translational speed, and working efficiency of the considerer robot under various operating conditions.

Modeling of Closure of Metallurgical Discontinuities in the Process of Forging Zirconium Alloy

This article presents the results of testing the conditions of closing foundry voids during the hot forging operation of an ingot made of zirconium with 1% Nb alloy and use of physical and numerical modeling, continuing research presented in a previous thematically related article published in the journal Materials. The study of the impact of forging operation parameters on the rheology of zirconium with 1% Nb alloy was carried out on a Gleeble 3800 device. Using the commercial FORGE®NxT 2.1 program, a numerical analysis was performed of the influence of thermo-mechanical parameters of the hot elongation operation in trapezoidal flat and rhombic trapezoidal anvils on the closure of foundry voids. The analysis of the obtained test results was used to formulate recommendations on the technology of hot forging and the anvilgeometry, ensuring closure of foundry voids. Based on their research, the authors conclude that the shape of the deformation basin and the value and hydrostatic pressure have the greatest influences on the closure of foundry voids.

Influence of Material Degradation on Deformation of Paraglider during Flight

The aim of this article is to determine experimentally and numerically the influence of material degradation on the deformation of a paraglider during flight. The presented method regards numerical modeling of pressure distribution over the wing and its effect on paraglider behavior; the considerations are preceded by experiments on three types of Polyamide 6.6 paraglider fabrics, subjected and not subjected to thermal, UV and flexing degradation. Scanning electron microscope (SEM) records allowed to determine the structural characteristics of the analyzed samples. Air permeability and mechanical tests are the input data for the computational simulations. When a pressure drop of 200 Pa is applied, all the analyzed samples are impermeable, except for those damaged by flexing. Thus, flexing damage has the greatest influence on the air permeability change among all considered aging factors. Aging caused by UV radiation has the greatest influence on mechanical properties. No major influence of thermal ageing on the mechanical properties of the considered samples is observed. Safety factors of the considered materials not subjected to degradation range between 3.94 and 6.00. Safety factor of fabric no. 1 subjected to the UV degradation is equal to 1.33; this result does not secure a safe usage of the considered material. The methodology described in this research can help to predict paraglider covering materials' behavior in flight; it assumes many cases, i.e., applying a new material or the material at any point of its life cycle. Thus, the practical implications of this model supported by numerical methods may result in saving time and cost in producing prototypes, as well as potentially assessing the safety of used wings. Future research activity can introduce the application of different elastic-plastic damage models to determine the paraglider behavior during collapse.

Improving Photovoltaic Performance of Hybrid Organic-Inorganic MAGeI3 Perovskite Solar Cells via Numerical Optimization of Carrier Transport Materials (HTLs/ETLs)

In this study, a hybrid organic-inorganic perovskite solar cell (PSC) based on methylammonium germanium triiodide (MAGeI3), which is composed of methylammonium (CH3NH3+) cations and germanium triiodide (GeI3-) anions, has been numerically studied using SCAPS-1d codes. An extensive investigation of various electron transport layers (ETLs) and hole transport layers (HTLs) was conducted to identify the most optimal device configuration. The FTO/ZnOS/MAGeI3/PEDOT-WO3 structure performed the highest efficiency of all combinations tested, with an impressive optimized efficiency of 15.84%. This configuration exhibited a Voc of 1.38 V, Jsc of 13.79 mA/cm2, and FF of 82.58%. J-V characteristics and external quantum efficiency (EQE) measurements indicate that this device offers superior performance, as it has reduced current leakage, improved electron and hole extraction characteristics, and reduced trap-assisted interfacial recombination. Optimum device performance was achieved at active layer thickness of 560 nm. These findings may also serve as a basis for developing lightweight and ultra-thin solar cells, in addition to improving overall efficiency. Furthermore, a comprehensive correlation study was conducted to evaluate the optimum thickness and doping level for both ZnOS-ETL and PEDOT-WO3-HTL. The photovoltaic performance parameters of the FTO/ZnOS/MAGeI3/PEDOT-WO3 structure were analyzed over a wide temperature range (275 K to 450 K). The structure exhibited stable performance at elevated operating temperatures up to 385 K, with only minimal degradation in PCE of approximately 0.42%. Our study underscores the promise of utilizing cost-effective and long-term stability materials like ZnOS and PEDOT-WO3 alongside the toxic-free MAGeI3 perovskite. This combination exhibits significant potential for eco-friendly PSC, paving the way for the development of highly efficient ultra-thin PSC.

Effect of Tendon-Related Variables on the Behavior of Externally CFRP Prestressed Concrete Beams

This work assesses the flexural performance of prestressed concrete beams with external carbon fiber-reinforced polymer (CFRP) tendons, focusing on tendon-related variables. A finite element analysis (FEA) method is verified. A numerical parametric analysis of prestressed concrete beams with external CFRP tendons is carried out. Four tendon-related variables are considered, namely, the area, initial prestress, depth and elastic modulus of tendons. The analysis shows that flexural ductility decreases as the tendon area, initial prestress or elastic modulus increases but is insensitive to the tendon depth. The ultimate tendon stress increment (Δσ_p) is influenced by all of the four variables investigated. JGJ 92-2016 (Chinese technical specification for concrete structures prestressed with unbonded tendons) significantly underestimates Δσ_p and, hence, is over-conservative for the strength design of these beams. An equation is proposed for calculating Δσ_p, taking into account all four variables investigated. An analytical model is then developed to estimate the flexural strength (M_u) of prestressed concrete beams with external CFRP tendons. The proposed analytical model shows good agreement with FEA, i.e., the mean discrepancy for Δσ_p is 0.9% with a standard deviation of 11.1%; and the mean discrepancy for M_u is -1.6% with a standard deviation of 2.1%.

A Simplified Dynamic Strength Analysis of Cardboard Packaging Subjected to Transport Loads

The article presents a simplified method for determining the strength of corrugated board packaging subjected to dynamic transport loads. The proposed algorithm consists of several calculation steps: (1) a static analysis of the compressive strength of the package, (2) an analysis of random vibrations in the frequency domain used to determine the resonance frequencies and (3) a dynamic analysis of the package loaded with computed resonant frequencies. For this purpose, numerical models of the static compression test of the packaging before and after the dynamic analysis of the package subjected to general transport loads were developed. In order to validate the model, laboratory packaging compression tests were also performed for samples of boxes using three-layer cardboard. Due to this, it was possible to verify the numerical simulation results of the compression tests for several box geometries. This, in turn, allowed for the development of a method based on dynamic and post-dynamic (static) numerical analyses, permitting a high-accuracy determination of the resistance of the selected packaging to vibrations and dynamic loads. The results of the (experimentally validated) numerical analysis proved the usefulness of the simplified method presented herein for precise estimation of the load capacity of various packages dynamically loaded during transport.

Magnetic Filler Polymer Composites-Morphology Characterization and Experimental and Stochastic Finite Element Analyses of Mechanical Properties

Polymer composites containing magnetic fillers are promising materials for a variety of applications, such as in energy storage and medical fields. To facilitate the engineering design of respective components, a comprehensive understanding of the mechanical behavior of such inhomogeneous and potentially highly anisotropic materials is important. Therefore, the authors created magnetic composites by compression molding. The epoxy polymer matrix was modified with a commercial-grade thickening agent. Isotropic magnetic particles were added as the functional filler. The microstructural morphology, especially the filler distribution, dispersion, and alignment, was characterized using microscopy techniques. The mechanical properties of the composites were experimentally characterized and studied by stochastic finite element analysis (SFEA). Modeling was conducted employing four cases to predict the elastic modulus: fully random distribution, randomly aligned distribution, a so-called "rough" interface contact, and a bonded interface contact. Results from experiments and SFEA modeling were compared and discussed.

Design and Modeling of a Miniature Hydraulic Motor for Powering a Cutting Tool for Minimally Invasive Procedures

Miniaturization of multifunctional instruments is key to evolving less invasive medical procedures. The current work outlines steps towards developing a miniature motor to power a cutting tool of a millimeter-scale robot/device (target outside diameter ~2 mm) for minimally invasive procedures. Multiple motor concepts were explored and ranked using a Pugh matrix. The single-rotor hydraulic design was deemed most viable for prototyping and scale-down to the target size. Prototypes were manufactured to be progressively smaller using additive manufacturing. The smallest prototype fabricated was 2:1 scale of the desired final size with a 2 mm outside diameter (OD) rotor and a device OD of 4 mm. The scaled prototypes with an 8 mm rotor were lab tested and achieved average speeds of 5000-6000 RPM at a flowrate of 15-18 mL/s and 45 PSI water pressure. Ansys CFX was used as a design tool to explore the parameter space and 3D transient simulations were implemented using the immersed solid method. The predicted rotor RPM from the modeling matched the experimental values within 3% error. The model was then used to develop performance curves for the miniature hydraulic motor. In summary, the single-rotor hydraulic design shows promise for miniaturization to the target 2 mm size.

Centurial Persistence of Forever Chemicals at Military Fire Training Sites

Drinking water contamination by per- and polyfluoroalkyl substances (PFAS) is widespread near more than 300 United States (U.S.) military bases that used aqueous film-forming foams (AFFF) for fire training and firefighting activities. Much of the PFAS at these sites consist of precursors that can transform into terminal compounds of known health concern but are omitted from standard analytical methods. Here, we estimate the expected duration and contribution of precursor biotransformation to groundwater PFAS contamination at an AFFF-contaminated military base on Cape Cod, Massachusetts, United States, by optimizing a geochemical box model using measured PFAS concentrations from a multidecadal time series of groundwater and a soil survey in the source zone. A toolbox of analytical techniques used to reconstruct the mass budget of PFAS showed that precursors accounted for 46 ± 8% of the extractable organofluorine (a proxy for total PFAS) across years. Terminal PFAS still exceed regulatory limits by 2000-fold decades after AFFF use ceased. Measurements and numerical modeling show that sulfonamido precursors are retained in the vadose zone and their slow biotransformation into perfluoroalkyl sulfonates (half-life > 66 yr) sustains groundwater concentrations of perfluorobutane sulfonate (PFBS) and perfluorohexane sulfonate (PFHxS). The estimated PFAS reservoir in the vadose zone and modeled flux into groundwater suggest PFAS contamination above regulatory guidelines will persist for centuries without remediation.

Electrokinetic and Electroconvective Effects in Ternary Electrolyte Near Ion-Selective Microsphere

The paper presents theoretical and experimental investigations of the behavior of an electrolyte solution with three types of ions near an ion-selective microparticle with electrokinetically and pressure-driven flow. A special experimental cell has been developed for the investigations. An anion-selective spherical particle composed of ion-exchange resin is fixed in the center of the cell. An enriched region with a high salt concentration appears at the anode side of the particle when an electric field is turned on, according to the nonequilibrium electrosmosis behavior. A similar region exists near a flat anion-selective membrane. However, the enriched region near the particle produces a concentration jet that spreads downstream akin to a wake behind an axisymmetrical body. The fluorescent cations of Rhodamine-6G dye are chosen as the third species in the experiments. The ions of Rhodamine-6G have a 10-fold lower diffusion coefficient than the ions of potassium while bearing the same valency. This paper shows that the concentration jet behavior is described accurately enough with the mathematical model of a far axisymmetric wake behind a body in a fluid flow. The third species also forms an enriched jet, but its distribution turns out to be more complex. The concentration of the third species increases in the jet with an increase in pressure gradient. The pressure-driven flow stabilizes the jet, yet electroconvection has been observed near the microparticle for sufficiently strong electric fields. The electrokinetic instability and the electroconvection partially destroy the concentration jet of salt and the third species. The conducted experiments show good qualitative agreement with the numerical simulations. The presented results could be used in future for implementing microdevices based on membrane technology for solving problems of detection and preconcentration, and thus simplifying chemical and medical analyses utilizing the superconcentration phenomenon. Such devices are called membrane sensors, and are actively being studied.

High-frequency irreversible electroporation improves survival and immune cell infiltration in rodents with malignant gliomas

Background

Irreversible electroporation (IRE) has been previously investigated in preclinical trials as a treatment for intracranial malignancies. Here, we investigate next generation high-frequency irreversible electroporation (H-FIRE), as both a monotherapy and a combinatorial therapy, for the treatment of malignant gliomas.

Methods

Hydrogel tissue scaffolds and numerical modeling were used to inform in-vivo H-FIRE pulsing parameters for our orthotopic tumor-bearing glioma model. Fischer rats were separated into five treatment cohorts including high-dose H-FIRE (1750V/cm), low-dose H-FIRE (600V/cm), combinatorial high-dose H-FIRE + liposomal doxorubicin, low-dose H-FIRE + liposomal doxorubicin, and standalone liposomal doxorubicin groups. Cohorts were compared against a standalone tumor-bearing sham group which received no therapeutic intervention. To further enhance the translational value of our work, we characterize the local and systemic immune responses to intracranial H-FIRE at the study timepoint.

Results

The median survival for each cohort are as follows: 31 days (high-dose H-FIRE), 38 days (low-dose H-FIRE), 37.5 days (high-dose H-FIRE + liposomal doxorubicin), 27 days (low-dose H-FIRE + liposomal doxorubicin), 20 days (liposomal doxorubicin), and 26 days (sham). A statistically greater overall survival fraction was noted in the high-dose H-FIRE + liposomal doxorubicin (50%, p = 0.044), high-dose H-FIRE (28.6%, p = 0.034), and the low-dose H-FIRE (20%, p = 0.0214) compared to the sham control (0%). Compared to sham controls, brain sections of rats treated with H-FIRE demonstrated significant increases in IHC scores for CD3+ T-cells (p = 0.0014), CD79a+ B-cells (p = 0.01), IBA-1+ dendritic cells/microglia (p = 0.04), CD8+ cytotoxic T-cells (p = 0.0004), and CD86+ M1 macrophages (p = 0.01).

Conclusions

H-FIRE may be used as both a monotherapy and a combinatorial therapy to improve survival in the treatment of malignant gliomas while also promoting the presence of infiltrative immune cells.

Study of Complexity of Numerical Models of a Strengthened Timber Beam

Laboratory research of wood-CFRP (carbon fiber reinforced polymer) structural elements, especially beams, is a scientific issue undertaken by many scientists. Research is often complemented with numerical analysis with the use of complex finite element method (FEM) models. Modern FEM software offers models that can reproduce such properties and phenomena as orthotropy and plasticity of wood and CFRP, delamination and mechanical behavior of adhesive layers, and damage of a strengthened element. The author of the paper reproduces numerical laboratory research of a four-point bending test of a glulam beam strengthened with CFRP tape. The main goal of the numerical research is an analysis of how the complexity of the FEM model influences the results of calculations, especially stress, deflection, and bearing capacity of the glulam beam. In some cases, a simpler model can be satisfactory, especially for a structural engineer, who takes into account serviceability limit states (permissible deflection of a structural member) and assumes that stress should not exceed the yield stress of timber.

Design of the Bimodal Grating Sensor with a Built-In Mode Demultiplexer

This new sensor design provides good volume sensitivity (around 1600 nm/RIU) via collinear diffraction by the asymmetric grating placed in the waveguide vicinity. It provides the mode transformation between the fundamental TE₀ and the first TE₁ modes of the silicon wire (0.22 μm by a 0.580 μm cross-section) in the water environment. In order to provide the wavelength interrogation with a better extinction ratio for the measuring signal, the grating design is incorporated with the mode filter/demultiplexer. It selects, by the compact directional coupler (maximum 4 μm wide and 14 μm long), only the first guided mode (close to the cutoff) and transmits it with small excess loss (about -0.5 dB) to the fundamental TE₀ mode of the neighboring single mode silicon wire, having variable curvature and width ranging from 0.26 μm to 0.45 μm. At the same time, the parasitic crosstalk of the input TE₀ mode is below -42 dB, and that provides the option of simple and accurate wavelength sensor interrogation. The environment index is measured by the spectral peak position of the transmitted TE₀ mode power in the output single mode silicon wire waveguide of the directional coupler. This type of optical sensor is of high sensitivity (iLOD~ 2.1 × 10^-4 RIU for taking into account the water absorption at 1550 nm) and could be manufactured by modern technology and a single-step etching process.

Modeling the Crack Interference in X80 Oil and Gas Pipeline Weld

Based on the numerical simulation method of the virtual crack closure technique (VCCT), an interference model was established to investigate the physical problem of two interacting cracks of different sizes in the welding zone of oil and gas pipelines. The obtained results of the current interference problem were compared with those of single crack case. Various crack configurations, such as different crack spacing and different crack sizes, were analyzed. The characteristic quantity fluid pressure load P during the crack propagation process, the peak value of the von Mises stress distribution field of the crack growth path, as well as the difference ∆Bx between the peak value of the magnetic induction intensity component at the crack and the value of the magnetic induction intensity component at its symmetrical position were calculated. The crack interaction scale factors, including γP, γMises, and γΔBx, were compared and analyzed. The numerical modeling results show that when the unequal-length double cracks interfere with each other, the cracks are more likely to propagate toward each other. The tendency of the double-cracks to propagate toward each other gradually weakens as the distance between the crack tips increases and is finally the same as that of single-crack cases. It was also found that the effect of large-sized cracks on small-sized cracks is greater than that of small-sized ones on large-sized ones. The numerical modeling results could be applied for the prediction and analysis of multicrack damage in oil and gas pipeline welds.

Electrochemical Oxidation for Treatment of PFAS in Contaminated Water and Fractionated Foam-A Pilot-Scale Study

Per- and polyfluoroalkyl substances (PFAS) are persistent synthetic contaminants that are present globally in water and are exceptionally difficult to remove during conventional water treatment processes. Here, we demonstrate a practical treatment train that combines foam fractionation to concentrate PFAS from groundwater and landfill leachate, followed by an electrochemical oxidation (EO) step to degrade the PFAS. The study combined an up-scaled experimental approach with thorough characterization strategies, including target analysis, PFAS sum parameters, and toxicity testing. Additionally, the EO kinetics were successfully reproduced by a newly developed coupled numerical model. The mean total PFAS degradation over the designed treatment train reached 50%, with long- and short-chain PFAS degrading up to 86 and 31%, respectively. The treatment resulted in a decrease in the toxic potency of the water, as assessed by transthyretin binding and bacterial bioluminescence bioassays. Moreover, the extractable organofluorine concentration of the water decreased by up to 44%. Together, these findings provide an improved understanding of a promising and practical approach for on-site remediation of PFAS-contaminated water.

A Numerical Study on the Effect of Tool Speeds on Temperatures and Material Flow Behaviour in Refill Friction Stir Spot Welding of Thin AA7075-T6 Sheets

A three-dimensional (3D) numerical model was created to simulate and analyze the effect of tool rotational speeds (RS) and plunge rate (PR) on refill friction stir spot welding (refill FSSW) of AA7075-T6 sheets. The numerical model was validated by comparing the temperatures recorded at a subset of locations with those recorded at the exact locations in prior experimental studies from the literature. The peak temperature at the weld center obtained from the numerical model differed by an error of 2.2%. The results showed that with the rise in RS, there was an increase in weld temperatures, effective strains, and time-averaged material flow velocities. With the rise in PR, the temperatures and effective strains were reduced. Material movement in the stir zone (SZ) was improved with the increment of RS. With the rise in PR, the top sheet's material flow was improved, and the bottom sheet's material flow was reduced. A deep understanding of the effect of tool RS and PR on refill FSSW joint strength were achieved by correlating the thermal cycles and material flow velocity results obtained from the numerical models to the lap shear strength (LSS) from the literature.

Vibration Serviceability of the Aberfeldy Footbridge under Various Human-Induced Loadings

Developing new structural materials, such as composite materials, has provided many opportunities in bridge engineering. Among these materials, glass-fiber-reinforced polymers (GFRPs), in particular, have found applications in footbridges. However, some of the commonly recognized advantages of GFRPs, such as the high values of the strength/weight ratio, can also be considered disadvantageous for certain realizations, particularly when the composite material used in a footbridge is, for example, subjected to dynamic actions such as those that are induced by wind and walking and/or running users. The induced accelerations can reach high values in comparison to recommended thresholds. Further, the natural frequency decays during the service life, reducing the capacity of the frequencies to move toward the frequency content of the pedestrian step. In this framework, the presented research is devoted to the dynamic comfort assessment of a pioneering cable-stayed GFRP pedestrian bridge, Aberfeldy, which was assembled in 1992 in the eponymous small town, which is located in Scotland (UK). The assessment was numerically performed through a finite element (FE) model, which was tuned based on the literature data concerning geometry, structural details, and in situ-acquired frequencies. The analyses carried out in this study include the evaluation of the accelerations' time histories, which were induced when simulating a set of pedestrian path scenarios, and the dynamic actions that occur during pedestrian traveling. Specifically, different values of velocity and step frequency were considered as well as the inclusion of walking and running movements. Then, based on the acceleration values, the assessments of comfort criteria for the current standards were elaborated while also recognizing that the peak accelerations-usually attained for short periods-cannot be the only parameters considered in evaluating the pedestrian bridge capacity. This investigation allowed a dynamic comfort rating to be established for the Aberfeldy footbridge.

Experimental and numerical study on failure mechanisms of bone simulants subjected to projectile impact

Analyses of the human bones failure mechanisms under projectile impact conditions can be made through performing of a large number of ballistic trials. But the amount of data that can be collected during ballistic experiments is limited due to the high dynamics of the process and its destructive character. Numerical analyses may support experimental methodologies allowing to better understand the principles of the phenomenon. Therefore, the main aim of the study was to create and to verify a numerical model of commercially available synthetic bone material-Synbone®. The model could be used in the future as a supporting tool facilitating forensic studies or designing processes of personal protection systems (helmets, bulletproof vests, etc.). Although Synbone® is commonly used in the ballistic experiments, the literature lacks reliable numerical models of this material. In order to define a numerical model of Synbone®, mechanical experiments characterizing the response of the material to the applied loads in a wide range of strains and strain rates were carried out. Based on the mechanical tests results, an appropriate material model was selected for the Synbone® composite and the values of constants in its equations were determined. Material characterization experiments were subsequently reproduced with numerical simulations and a high correlation of the results was obtained. The final validation of the material model was based on the comparison of the ballistic impact experiments and simulation results. High similarity obtained (relative error lower than 10%) demonstrates that the numerical model of Synbone® material was properly defined.