Penetration Phenomena Research Articles

Analysis of Sandwich Composite Subjected to Impact Loading for Enhanced Energy Absorption

Abstract Composite materials are engineered to achieve the balance of properties for a wide spectrum of applications. In the current work, PU foam is used as a core, and Epoxy E-Glass (UD) is used as a face sheet. Impact of sandwich composite with single core and double core are considered. The effect of energy absorption, contact force, residual velocity, and deformation on impact velocity are discussed. The phenomenon of perforation, penetration and rebounding was observed in 150 m/s, 130 m/s and 100 m/s respectively. The FE tool ANSYS is used for analysis. It was found double core sandwich composite absorbs more energy and even stiffer than single core sandwich composite.

Mechanical behaviour and instability mechanism of sandstones with impact tendency under different loading paths

ABSTRACT To reveal the instability and failure mechanism of pillars with impact tendency, the Brazilian test, uniaxial compressive test, cyclic loading and unloading (CLU) tests were performed on sandstones which had impact tendency. The stress drop phenomenon was obvious in the fracture stage during the Brazilian test. The main tensile crack with penetration type appeared. Under the CLU condition, the CLU had a significant effect in enhancing the mechanical character of rocks. Under the combined loading, the character stress of rocks tested with the CLU was greater than the uniaxial loading. Moreover, the greater the first cyclic threshold, the greater the character stress of rocks. Under the uniaxial loading, the failed samples showed tensile fractures. The damage location of the samples was closely related to the Poisson effect and the ending face effect. With the electron microscope which had the same magnification, the crack deterioration degree of samples under the uniaxial loading was greater than the CLU condition. Moreover, with the first cycle threshold increasing, the surface roughness of rocks gradually decreased. The quantity of secondary micro cracks gradually decreased. The propagation and penetration phenomenon gradually disappeared. The micro structure and loading properties of rocks were affected by the bonding force and structural characters between the internal structure and matrix. Based on the micro-seismic signal of the damaging threshold, the seismic source damage location can be located. Moreover, the pillar-typed burst area can be forewarned. This research benefits predicting the pillar-typed burst disaster.

Spreading and Capillary Imbibition of Viscous Oil Lens into an Open-Cell Porous Structure.

Oil pollution in the ocean is becoming more and more of a serious issue, which increases interest in both ways for combating its cause and methods for observing and monitoring how oil spreads. A promising approach based on an optical method with empirical relations for selected viscous oil-water systems is presented. Based on a modified melamine sponge (MMS), the microscopic spreading and oil capillary penetration phenomenon of the porous structure were investigated. The objective of this study is 2-fold: (i) to present a more thorough experimental description of the spreading of viscous oil lens on the water surface and capillary action of oil lens into MMS porous structure; and (ii) to provide a theoretical description that helps to explain some of the observed behavior. With knowledge of , we can determine the spreading coefficient S. It needs to be pointed out that the oil lens floating on the water surface does satisfy Neumann's rule as the spreading coefficient of the air-oil-water system is negative (- 9.8 mN/m), indicating the ability to form a stable oil lens with thickness δO = 3.04 mm and radius RL = 38.64 mm after 60 min of spreading test. Furthermore, to better understand the capillary phenomena from a mechanical approach, an oil lens in contact with the surface of the MMS porous structure, by in-depth visualization, is properly defined as the balance of forces acting. Finally, as an illustration of this method, we utilized this approach to obtain the equilibrium height of the capillary rise and take it into account in terms of effective material thickness.

The penetration phenomenon of the expiratory airflow from thermal plume of human body in the microenvironment around people

Understanding the influence of the human body's thermal plume on exhaled airflow is crucial for accurately assessing indoor infection risks. This study employs numerical simulations and a jet integral modeling method to investigate the airflow dispersion patterns of a single thermal manikin during sustained expiration. It was found that the thermal plume formed a two-stage evolution in exhaled airflow. Initially, the airflow was weakened by the thermal plume in the horizontal dispersion, and subsequently it was bent due to the entrainment of the surrounding air in the upward dispersion of the exhaled airflow. The thermal plume changes the trajectory and lateral dispersion distance of exhaled airflow. When the exhalation velocity is 1 m/s, the airflow is fully deflected towards the head plume region. When the exhalation velocity is between 1.5 and 2 m/s, the airflow is partially deflected, with only part of the upper airflow deflected towards the head plume region. In addition, it is interesting to note that the plume changes the dispersion trajectory of the exhaled airflow, while still adhering to the distributions of buoyant jet flow. This study suggests that the thermal effect of the human body is a significant factor in characterizing the dispersion of exhalation airflow and aerosols. Considering the thermal plume in indoor infection risk assessment is expected to yield more reliable data for theoretical modeling of respiratory airflow transport.

A phase field-immersed boundary-lattice Boltzmann coupling method for fluid-structure interaction analysis

Fluid-structure interaction (FSI) is critical in numerous engineering and scientific applications. This paper presents a numerical model for FSI simulations that integrates the lattice Boltzmann method (LBM) for fluid dynamics, the phase field method (PFM) for structural deformation and fracture, and the immersed boundary method (IBM) for fluid-solid coupling. The fluid employs an explicit time integration scheme with a smaller time step than the solid, which uses an implicit time integration scheme, satisfying the CFL condition. During the synchronization of fluid-solid interaction information, a multi-substep strategy is applied. The IBM is implemented using the iterative velocity method for boundary treatment. This approach facilitates the information transfer between domains with different time steps, enhancing the coupling accuracy through iterative computation. The effectiveness of the improved immersed boundary-lattice Boltzmann (IB-LBM) has been verified by the classical cylindrical flow case, which effectively prevents the particle penetration phenomenon and improves the calculation accuracy. The phase field-immersed boundary-lattice Boltzmann method (PF-IB-LBM) is subsequently deployed to simulate the deformation of an aluminum plate under hydrostatic pressure and the aftermath of a dam-break impact on an elastic plate. Verification of the coupling method substantiates its feasibility and efficacy. In addition, the proposed PF-IB-LBM is implemented to simulate the entire process of structural deformation and failure in response to fluid dynamics, which further confirms its capability to predict discontinuous mechanical behaviors such as damage and crack propagation under intricate fluid flows. The results emphasize the flexibility and efficiency of the proposed approach, providing a robust framework for solving more complex scenarios in engineering FSI problems.

Vizantijskij tranzit yuridicheskoj iudaiki v otechestvennoe ugolovnoe pravo

he purpose of this work is to study the historical and legal phenomena of penetration into the legal space of Russia provisions of Hebrew law in the process of global reception of Christianized law of the Eastern Roman Empire in the 11th 17th centuries. Judaica not only influenced the formation of domestic legal acts (in the aspects of legal goal-setting, the specifics of legal technology, etc.) the provisions of the Law of Moses were included as an autonomous segment in systematized domestic codes and were subject to direct application by state authorities of Russia. Understanding the true historical roots of the formation of domestic law forms the foundation for its development currently and release the reform of Russian criminal law from artificially imposed dependence on the trends in the development of European public law.

Feasibility of kinetic orbital bombardment

Abstract In this paper, the possible impact effects of orbital bombardment systems and their feasibility are studied. These effects are the projectile penetration into concrete and steel targets and seismic effects. The equations of motion for the re-entry of a projectile and the penetration were solved numerically. The projectile penetration is modelled using the Alekseevskii–Tate model. By varying the altitude (h), projectile length (L), manoeuvre velocity (ΔV) and the target properties, the flight time (t), earthquake magnitude (M) and penetration depth (P) are calculated. The calculations show that the impact of a tungsten alloy rod with a length of 8 m and a 0.4 m diameter results in an earthquake with a seismic magnitude of only 2.5 on the Richter scale. For concrete, the optimal result is obtained for a projectile with a length of 0.56 m. It penetrates 1.79 m with a minimal ΔV trajectory. These results show that a kinetic orbital bombardment system is not feasible without major technological developments, the impact angle being a bottleneck of the concept. Moreover, one has to accept very high costs. Without any means to change the attitude of the projectile, using ICBMs or bombers shows a better penetration performance than re-entry. Highlights Weapons in orbit may provide a strategic advantage. However, they are restricted by international space laws. Impact angle of the projectile is a bottleneck for kinetic orbital bombardment. Larger impact angles can be achieved, but at the expense of a larger mass-to-orbit. A hypersonic drag device may be used to optimise the impact angle and thus improve the system. Alternative projectile delivery methods (Bomber, Intercontinental Ballistic Missile (ICBM)) show better performance for both steel and concrete targets. Essentially, only penetration phenomena matter because the seismic effects are not significant. Therefore, orbital bombardment systems don’t even resemble weapons of mass destruction (WMD). Given their limited effect, destroying a particular target requires a guidance and flight control system, which, given the high velocities, may not be feasible.

Umbilical therapy for promoting transdermal delivery of topical formulations: Enhanced effect and underlying mechanism

Umbilical paste therapy is a promising method to promote transdermal drug delivery of topical formulations. This work investigated the effect and mechanism of transdermal drug delivery through the umbilical skin. The transdermal permeation studies showed the phenomenon of higher cumulative penetration and faster penetration rates for drug through the umbilical skin compared with non-umbilical skin, namely umbilical pro-permeability. This special transdermal permeability of drugs is influenced by their molecular weight, logP value, ability to form hydrogen bonds, and molecular volume. The underlying mechanism of umbilical pro-permeability was elucidated from unique structure and regulation the effect of drugs on microcirculation in the umbilical skin. Mechanistic studies revealed that this phenomenon was not only associated with the structural and physiological properties of the skin but also to the interactions between drugs and different skin layers. The umbilical pro-permeation is attributed to the thinner stratum corneum layer, differences in stratum corneum lipid composition and keratin structure, and lower levels of intercellular tight junction proteins in the viable epidermis and dermis layer of the skin. Our research indicated that umbilical paste therapy enhanced the transdermal delivery and absorption of drugs by stimulating local blood flow through mast cell activation. Surprisingly, skin temperature modulation and calcitonin gene-related peptide and substance P levels did not appear to significantly affect this process. In conclusion, umbilical drug administration, as a straightforward and non-invasive approach to enhance transdermal drug delivery, presents novel concepts for continued investigation and practical implementation of transdermal drug delivery systems.

Three-dimensional modeling of impact fractures in brittle materials via peridynamics

Accurate prediction of the impact fracture behavior of brittle materials is crucial in various industries. The paper employs the peridynamic method to model the penetration and damage in brittle materials during impact. The proposed three-dimensional peridynamic impact fracture model (3D-PDIFM) overpasses other numerical models by adopting a new computational technique to couple the impact collisions of different types of projectiles with the peridynamic method. Moreover, the 3D-PDIFM is highly efficient in impact fracture simulations by focusing on the effects of the projectile without simulating its particles, thereby saving more computational efforts. Validation through comparison with experimental measurements and observations ensures that the 3D-PDIFM accurately represents the real-world impact fracture behavior of brittle materials. The paper also highlights the efficiency of the 3D-PDIFM in comparison to traditional mesh-based numerical simulations. Therefore, the 3D-PDIFM can be significant for practical engineering applications as efficient simulations can save time and computational resources. Using the validated model, the impact fracture behavior of PMMA under various conditions, such as changes in panel thickness, impact area, and projectile velocity, is investigated. This analysis gains more insights into how these factors affect the brittle material's response to impact. Moreover, the impact fracture behaviors of tempered glass and float glass panels are examined under different conditions of impact loadings. This study also explains the penetration and impact fracture phenomena in brittle materials. Overall, using the 3D-PDIFM as a modeling and simulation tool can help engineers and researchers analyze the behavior of glass panels under various impact scenarios, thus allowing for optimization of design parameters to improve impact resistance.

Dynamic penetration behaviors of graphene origami under high-velocity impact

Brittleness remains the key bottleneck for graphene to be used as impact protection materials and this obstacle can be overcome by origami-modified graphene. Herein we employed molecular dynamics simulation to investigate the perforation behaviours of graphene origami (GOri) under ballistic impact from a diamond projectile. We found that the threshold penetration velocity of GOri can be improved significantly by 46.27 % compared with that of its pristine counterpart. Under a small ballistic impact loading at a low speed, GOri experiences a unique unfolding process and hence has improved impact-resistance performance. Depending on the initial velocity of the projectile, three different penetration phenomena are observed, i.e. bounce-back, capture, and perforation state. The penetration energy depends on the roughness of GOri, the initial impact velocity, the projectile's radius and the layer number. This study provides useful insights into the perforation behaviours and energy absorption of GOri and offers useful guidelines for graphene applications as impact protection materials.

Identification of female-enriched and disease-associated microglia (FDAMic) contributes to sexual dimorphism in late-onset Alzheimer’s disease

BackgroundLate-onset Alzheimer’s disease (LOAD) is the most common form of dementia; it disproportionally affects women in terms of both incidence rates and severity of progression. The cellular and molecular mechanisms underlying this clinical phenomenon remain elusive and ill-defined.MethodsIn-depth analyses were performed with multiple human LOAD single-nucleus transcriptome datasets to thoroughly characterize cell populations in the cerebral cortex. ROSMAP bulk human brain tissue transcriptome and DNA methylome datasets were also included for validation. Detailed assessments of microglial cell subpopulations and their relevance to sex-biased changes at the tissue level were performed. Clinical trait associations, cell evolutionary trajectories, and transcription regulon analyses were conducted.ResultsThe relative numbers of functionally defective microglia were aberrantly increased uniquely among affected females. Substratification of the microglia into different subtypes according to their transcriptomic signatures identified a group of female-enriched and disease-associated microglia (FDAMic), the numbers of which were positively associated with disease severity. Phenotypically, these cells exhibit transcriptomic signatures that support active proliferation, MHC class II autoantigen presentation and amyloid-β binding, but they are also likely defective in phagocytosis. FDAMic are likely evolved from female activated response microglia (ARMic) with an APOE4 background and compromised estrogen receptor (ER) signaling that is deemed to be active among most subtypes of microglia.ConclusionThis study offered important insights at both the cellular and molecular levels into how ER signaling affects microglial heterogeneity and function. FDAMic are associated with more advanced pathologies and severe trends of cognitive decline. Their emergence could, at least in part, explain the phenomenon of greater penetrance of the APOE4 genotype found in females. The biases of FDAMic emergence toward female sex and APOE4 status may also explain why hormone replacement therapy is more effective in APOE4 carriers. The pathologic nature of FDAMic suggests that selective modulations of these cells may help to regain brain neuroimmune homeostasis, serving as a new target for future drug development.

Settlement rule of underpass railway model in shield tunnel and influence of nanomaterials on slurry performance during construction

In the shield tunnel, the phenomenon of structure penetration occurs frequently. Therefore, strict control of ground subsidence is imperative during the construction phase. In addition, other variables may be influence the performance of the slurry during the grouting procedure. This study aims to investigate and analyze the impact of nanomaterials on the properties of slurry used in construction, with the goal of determining the optimal construction route for the shield, ensuring quality construction of a U-shaped section, and meeting settlement control requirements. Firstly, the impact of double line spacing on the subsidence of U-shaped grooves is analyzed. Subsequently, the influence of common nanomaterials on slurry properties is examined through compressive strength testing. Among these nanomaterials, micro-silica powder exhibits the most significant enhancement effect on construction slurry performance with an optimal content of 5%. If the content of silica powder reaches 5%, the initial strength and later strength of the cement slurry will increase by 35% and 25% respectively, thereby promoting the enhanced performance of the slurry. In this study, the settlement of a U-shaped groove on the surface and subgrade is controlled by the settlement of a shield tunnel underpass railway model based on the distance between shield construction lines, providing valuable insights for future constructions with similar characteristics.

Impact of H2/CH4 blends on the flexibility of micromix burners applied to industrial combustion systems

The present paper investigates the feasibility of using H2/CH4 fuel blends in micromix-type burners applied to industrial combustion systems. The micromix burner concept, characterised by the formation of miniaturised and compact turbulent diffusion flames, was developed for gas turbine hydrogen burners showing low NOx emissions (below 10 ppm) without flashback risk, which represent the main issues when using pure hydrogen or hydrogen enriched natural gas blends as fuel, making it a promising concept to be applied in industrial burners. The study was carried out through numerical CFD simulations, accounting for detailed chemistry calculations of turbulent micromix flames and previously validated through experimental measurements in a laboratory-scale micromix burner prototype. The resulting flow, temperature and exhaust emission characteristics for three H2/CH4 fuel blends with H2 content of 90, 75 and 60% respectively were analysed and discussed for air-fuel equivalence ratios at λ=1.8 and 1.6 (lower than the well-characterised air-fuel equivalence ratios in micromix gas turbine burners at λ=2.5 and closer to current industrial burners), considering an energy density of 14 MW/m2 bar. Numerical results showed low fuel flexibility for industrial-scale micromix burners, with still low NOx emissions (12–85 ppm) but relatively high CO emissions (448–4970 ppm) for the considered blends and λ values. The lowest CO emissions were given together with jet penetration phenomena, ruling out the feasibility of these design points due to the greater importance of the latter phenomenon.

Numerical Study of Fluid Flow and Mixing in the Argon Oxygen Decarburization (AOD) Process

A three-dimensional (3D) model has been developed based on the Eulerian multiphase flow approach to investigate the fluid flow behavior and mixing efficiency in the multi-tuyere AOD process. The interphase forces, including drag force, lift force, virtual force, turbulent dispersion force, and wall lubrication force, were incorporated into this model. The model was used to simulate six-tuyere and seven-tuyere AOD processes. The phenomena of multi-jet penetration, bubble plume merging, 3D turbulent flow and mixing characteristics were considered. The results indicate that the bubble plume merging occurs in the upper part of the liquid bath, forming a typical plume cluster. The predicted penetration length for a single tuyere jet agrees well with the previous work. For the multi-jet system, the side jets penetrate deeper than the inside ones. The six-tuyere AOD has a good flow condition in the center of the liquid bath, while the seven-tuyere AOD has a better flow pattern in the sidewall region and the lower bath. Overall, the seven-tuyere AOD performs better in mixing efficiency than the six-tuyere AOD under the same gas flow rate. These findings increase the understanding of the AOD process, allowing further optimization of process parameters. This model can be further extended to incorporate the thermochemical reactions into the modeling of the AOD reactor.

A Non-Equilibrium Interpolation Scheme for IB-LBM Optimized by Approximate Force

A non-equilibrium scheme and an optimized approximate force are proposed for the immersed boundary–lattice Boltzmann method (IB-LBM) to solve the fluid–structure interaction (FSI) equations. This new IB-LBM uses the discrete velocity distribution function and non-equilibrium distribution function to establish the interpolation operator and the spread operator at the mesoscopic scale. In the interpolation operator, we use the force model of LBM to derive a direct force with a simple form. In the spread operator, we give a theoretical proof with local second-order accuracy of the spread process using the non-equilibrium theory from the LBM. A non-iterative explicit force approximation scheme optimizes the direct force in that the streamlines have no penetration phenomenon, and the no-slip condition is strictly satisfied. Different from other schemes for the IB-LBM, we try to apply the non-equilibrium theory from the LBM to the IB-LBM and obtain good results. The explicit force obtained using the non-equilibrium scheme and then optimized via the non-iterative streamline correction equation simplifies the explicit direct force scheme and the original implicit scheme previously proposed but obtains a similar streamline correction result compared with the implicit method. Numerical tests prove the applicability and accuracy of this method in the simulation of complex conditions such as moving rigid bodies and deforming flexible bodies.

Determination of carbon nanotubes penetration level into epoxy-woven glass fibre composite laminates manufactured with vacuum infusion process via electrical conductivity measurement

ABSTRACT This study investigates the carbon nanotube (CNT) penetration phenomenon in vacuum infusion (VI) process by means of electrical conductivity measurement. Effects of resin temperature, CNT content, and the processing technique on the overall composite laminate quality were investigated by monitoring electrical properties of composite sheets. Epoxy/woven glass fibre composites loaded with various CNT contents were also manufactured using compression moulding and vacuum bagging techniques for comparison purposes. VI was achieved at two different temperatures (25°C and 50°C) to study the effect of variation in viscosity on CNT penetration during infusion. The results showed that electrical conductivity measurement was a very effective tool to assess the CNT penetration state of composite laminates in VI method. Both the resistive and capacitive behaviour in composite laminates due to filtration of CNTs at higher CNT contents was observed. However, the CNT penetration was improved by increasing the temperature of epoxy/CNT mixture before the infusion.

Investigation and modeling of electric vehicle enablers (EVE) for successful penetration in context to India: mitigating the effect of urban sprawl on transportation.

Urban sprawl in context to transportation is a matter of serious concern. It creates unusual environmental challenges for an emerging economy like India, known for geographical spread, population, and use of fossil fuel-based automobiles on road. Indian automotive sector is often held responsible for the emission of greenhouse gasses causing serious environmental deterioration. Government at both central and state levels is dealing with this challenge in two ways-adding more infrastructure for public transport and encouraging electrical vehicles (EVs). Adoption of EVs for public mobility is eco-friendlier and economic. But it is observed that EV penetration in many pockets is not growing and is yet to mature for usage. Regardless of subsidies, it is not picking up as expected and needs to be investigated. Earlier research mainly focused on reporting barriers and did not guide EV penetration enablers. This study bridges the research gap and offers useful insights about EV penetration phenomenon and makes use of both qualitative and quantitative treatments. Accordingly, it models thirteen enablers, guides about tangling interrelationships using an interpretive structural modeling (ISM), and validates it using best worst method (BWM) approach. The study reports six key enablers, which are-developing high-capacity batteries with short recharge time, improving service support, framing promotive government policies, lowering electricity tariffs using sustainable and reliable sources, and reducing dependence on imported raw materials. These enablers need an urgent attention from the industries and researchers for successful EV penetration in Indian context. Authors hope the findings will be useful for other developing countries as well and will influence both researchers and practitioners.

Study on Calibration Method for Ion Concentration Measurement Parameters of Ion Selective Electrode Based on Multiple Linear Regression

In the drilling industry, the change of ion concentration of drilling fluid can provide a basis for judging whether it enters the target layer and whether there is a layer penetration phenomenon during the drilling process. Traditional ion concentration determination methods require manual operation, time-consuming and labor-intensive, and most of them have problems such as large measurement errors, measurement cycles and in-line measurements, so for these problems, there is an urgent need for a fast and real-time measurement measurement method. The ion-selective electrode method allows accurate and real-time measurement of chloride, sulfur and potassium ions, but due to the mechanism of the ion selective electrode method, mutual interference occurs when multiple ions coexist. Aiming at the problem of low efficiency of traditional measurement methods and multi-ion interference with each other in ion-selective electrode method. In this paper, an ion concentration calibration method based on multiple linear regression is proposed, and the error cause of the ion selective electrode method is analyzed first, and the measurement value is calibrated in combination with the multiple linear regression model, and finally the ion concentration experimental platform is established, and the results of the measurement accuracy of chlorine, sulfur and potassium ions are improved by more than 90%, which proves the effectiveness of the proposed method.

External Jugular Vein Perforation by the Transverse Cutaneous Nerve of The Neck: A Case Report and Review of The Literature.

A very rare anatomical variation of external jugular vein's penetration by the transverse cutaneous nerve of the neck is displayed in the current study. The phenomenon of veins' fenestration or penetration by other structures, such as nerves along with its likely embryologic development are discussed. Moreover, the potential clinical significance of that variation's awareness on behalf the physician is discussed in detail.

Numerical Study on the Turbulence Penetration and Thermal Stratification Characteristics of CFETR Divertor PHTS Pressurizer Surge Line

The thermal stress and thermal fatigue caused by the turbulence penetration and thermal stratification could cause damage to the pressurizer surge line, which will further endanger the safe operation of the divertor primary heat transfer system (PHTS) in the China Fusion Engineering Test Reactor (CFETR). In this article, the new criteria for determining the length of turbulence penetration and thermal stratification level are proposed to predict turbulence penetration and thermal stratification behaviors. The velocity W (velocity component in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z$ </tex-math></inline-formula> -axis direction) and temperature gradient can be used as criteria to judge penetration length. Meanwhile, the stratification intensity factor is considered as a criterion of the thermal stratification level. According to the computational fluid dynamics (CFD) simulation results and the criteria, it is observed that the swirling penetration phenomenon occurs in the turbulence penetration region, and the penetration length is 1.35 m. It is also found that the most severe thermal stratification occurred in this position with a stratification intensity factor of 0.67. This work lays a foundation for the surge line analysis in the field of fusion reactor such as CFETR and provides the reference for evaluating the thermal state of the surge line in the future.