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The Lamb-type waves in the homogeneous isotropic thermally conducting porous plate immersed in the inviscid fluid in the context of the Lord and Shulman theory of thermoelasticity are studied. To seek out solutions, the Helmholtz decomposition technique is used. Plugging the solutions in the appropriate boundary conditions, a secular equation is derived for the symmetric and anti-symmetric family of wave modes. It is found that shear horizontal wave mode uncouples itself from the coupled system of waves. Particular cases of the secular equation have also been deduced in the absence of fluid or certain energy fields such as thermal field and/or volume fractional field. Different regions of the secular equation are obtained. Furthermore, these regions have been led to peculiar cases such as short-wavelength, and long-wavelength waves. The amplitude of displacement, change in volume fraction field, and temperature distribution is computed and compared with prior accomplished research work. The numerical computations are carried out for a porous magnesium plate immersed in water to understand the behavioral pattern of waves, and the various graphs are plotted to defend the analytical findings. [ABSTRACT FROM AUTHOR]

The current research presents a new model on a volume fraction branch of Knowledge and photothermal effect in a semiconductor generalized thermoelasticity medium according to the Lord-Shulman Theory. The governing equations are provided considering voids, photothermal, semiconducting, and the theory of generalized thermoelasticity. The authors make use of the normal mode examination to solve the order of the equations in this phenomenon under the boundary conditions. The achieved results demonstrate the effect of photothermal, voids, the process of semiconductor, and the thermic relaxation time. The compared physical fields are given analytically and displayed in graphs. The achieved results display the possibility of applying the combination of the photothermal and semiconductors medium in biophysical, industries, structures, engineering, and chemical products with consideration of the photothermal, semiconducting, and voids. [ABSTRACT FROM AUTHOR]

The present work is devoted to discuss the transient wave propagation in an isotropic homogenous thermoelastic spherical body with voids due to harmonically varying heat sources in the context of nonlocal thermoelasticity. The constitutive relations and the governing equations are resolved by applying harmonic variations in time and transformed into coupled ordinary differential equations. The outer and the inner surfaces of the sphere are kept stress-free and free from void concentration. A harmonically varying heat source is supplied on the inner surface along the radial direction and the outer surface is assumed to be isothermal. Numerical simulations are implemented to the analytical results with the support of MATLAB software tool. Numerically, generated data are presented graphically for the field variables of interest (temperature, stresses, cubical dilation, displacement and void volume fraction field) and at the end analysis of these results are given. [ABSTRACT FROM AUTHOR]

This work presents results of numerical simulations to investigate the effect of different void percentages on composite materials' Coefficient of Thermal Expansion (CTE) and local stress fields. A random distribution of voids is considered within the Representative Volume Element (RVE) matrix, and different types of microstructures are considered, including square-packed and randomly distributed fibers. The use of a higher-order beam model within the framework of Carrera Unified Formulation (CUF) leads to a Component-Wise (CW) approach, resulting in an accurate, 3D description of the cross-section although using a 1D formulation. Numerical results for different fiber volume fractions and void concentration percentages demonstrate the agreement of the computed effective coefficients of thermal expansion of the present micromechanical thermoelastic model with references from the literature. The local stress fields are affected by voids, with higher effects over the matrix. Furthermore, higher void fractions lead to higher variability of stress peaks. [ABSTRACT FROM AUTHOR]

This study utilizes Direct FE2 multiscale simulation techniques to propose an innovative approach for analyzing hydrogen diffusion in Zircaloy cladding. This method combines finite element simulations at two scales into a monolithic framework by utilizing downscaling rules and scaling factors. Through the investigation, it was found that voids induce non-uniform diffusion of lattice hydrogen, demonstrating a strong correlation between trapped concentration and microstructure. Additionally, the accumulation of trapped hydrogen leads to localized plastic deformation and a reduction in effective diffusivity. Furthermore, two representative volume elements were established to depict the void distribution at various stages of its evolution. It is evident that in the initial phases of void evolution, the hydrogen-induced softening effect facilitates crack propagation deep within the zirconium alloy cladding. Moreover, as void evolution progresses into the second stage, this effect intensifies the incidence of localized damage at the narrow inter-void ligaments. [ABSTRACT FROM AUTHOR]

In this work, the Dy 2 O 3 -Al 2 O 3 -SiO 2 (DASN) and Dy 2 O 3 -Al 2 O 3 -SiO 2 -TiO 2 (DAST) glass fillers were used for joining alumina ceramic. During the cooling process of the alumina/DASN/alumina joints, Dy 2 Si 2 O 7 and Al 2 O 3 were precipitated simultaneously and gradually grown. As a result, voids were formed due to the poor flowability of the glass ceramic filler and the large density difference between the glass filler and Dy 2 Si 2 O 7 crystals. On the contrary, the addition of TiO 2 altered the sequence of the crystalline phase precipitation during the cooling process. During cooling from the joining temperature (1450 °C) to 1100 °C, only Dy 2 Si 2 O 7 was formed in the brazing seam. Simultaneously, the flowing glass phase was able to fill the spaces caused by the density differences. When the growth of Dy 2 Si 2 O 7 phase ceased, the Al 2 O 3 phase began to precipitate. Therefore, the voids caused by density differences can be eliminated in the alumina/DAST/alumina joints with high crystallinity. The optimal flexural strength of alumina/DAST/alumina joints tested at room temperature and 1000 °C reached 350 MPa and 158 MPa, respectively. [ABSTRACT FROM AUTHOR]

Highlights Carbon fiber reinforced resin matrix composites, when subjected to multi‐angle delamination during vacuum hot pressing, suffered from defects such as uneven fiber distribution, resin‐rich zones, and voids. These defects caused varied damage and failure behaviors in the composites, seriously affecting their mechanical properties. In this paper, the defect distribution, tensile and flexural properties, and damage behaviors of multi‐angle lay‐up specimens prepared in an autoclave were studied. The results indicated that irregularly shaped voids in laminates with a 0° angle difference primarily led to local stress concentration. Elliptical and elongated voids in laminates with a 90° angle difference were mainly susceptible to delamination. The [0/90]8 layer exhibited the best overall mechanical properties. The proportion of 0° laminates had a direct impact on the mechanical properties, with 0° contact laminates on the bending‐compression side capable of withstanding higher bending loads. The [+45/−45]8 plyer demonstrated pseudo‐delayed behavior, enabling the laminate to show better toughness under load. Variations in damage due to the proportions and positions of the laminates influenced the mechanical properties and damages behavior of multi‐angle laminates. Angular differences were observed to affect void and resin distribution. The best overall mechanical properties were attributed to [0/90]8 laminates. Pseudo‐delay behavior was exhibited by [+45/−45]8 laminates. Proportion of 0° layers impacted mechanical properties. Greater bending loads were withstood by the 0° contact layer. [ABSTRACT FROM AUTHOR]

In this study it is approached a linear model for the mixture of two Cosserat bodies having pores. It is formulated the mixed problem with initial and boundary data in this context. The main goal is to show that the coefficients that realize the coupling of the elastic effect with the one due to voids can vary, without the mixture being essentially affected. In a more precise formulation, this means that a small variation of the coefficients in the constitutive equations of the two continua causes only a small variation of the solutions of the corresponding mixed problems, that is, the continuous dependence of the solutions in relation to these coefficients is ensured. The considered mixture model is consistent because all estimates, specific to continuous dependence, are made based on rigorous mathematical relationships. [ABSTRACT FROM AUTHOR]

This paper addresses a significant research gap in the study of surface waves propagation in a nonhomogeneous, within a magneto-thermoviscoelastic material of higher order, initial stress, rotation, gravity effects and voids. This study provides analytical solutions for surface waves propagating through a medium consisting of a magneto-thermoelastic material with voids under the rotation, electro-magnetic field, gravity field and initial stress. The analytical solutions are derived for the displacement components, volume fraction, temperature to Stoneley and Rayleigh waves are computed numerically and presented graphically considering the external parameters impact. Furthermore, this investigates how magnetic field, voids, gravity, initial stress and fiber-reinforced parameters influence these wave phenomena. This investigation provides valuable insights into the synergistic dynamics among electric constituents, voids, Stoneley and Rayleigh waves propagation, enabling advancements in sensor technology, augmented energy harvesting methodologies, and pioneering seismic monitoring approaches. For certain materials, numerical simulations are provided and graphically displayed. The results of this study reveal several unique cases that significantly contribute to the understanding of Rayleigh and Stoneley waves propagation within this intricate material system, particularly in the presence of voids. [ABSTRACT FROM AUTHOR]

Voids behind tunnel linings can be formed either during or after the construction phase, occurring due to inadequate backfilling, substandard workmanship, water erosion, or gravitational forces. Investigations into numerous tunnels in which collapses occurred while in operation have indicated that voids behind the liner constitute the primary contributors to these failures. Consequently, it is imperative to devise lining reinforcement strategies tailored to the specific conditions encountered in the field. Fiber-reinforced plastic (FRP) represents a viable alternative construction material that has been widely utilized in the reinforcement of concrete structures. It is essential to quantitatively assess the reinforcing effect of FRP grids when they are employed in the restoration of deteriorated tunnel linings, thereby facilitating the development of effective maintenance designs. In this study, we aimed to enhance the sensitivity analysis of the reinforcement method by evaluating the impact of voids through the analysis of bending moments and axial forces within the tunnel lining. The effects of voids based on the different locations in which they occur were explored numerically through an Elastoplast finite element analysis. The study involved simulating tunnel linings that had been reinforced with FRP grids and assessing the effects of such reinforcement in tunnels afflicted with various structural problems. Based on the outcomes of these simulations, the internal forces within the lining are scrutinized, and the efficacy of the reinforcement is appraised. [ABSTRACT FROM AUTHOR]

This paper aims to obtain solutions in terms of the complex potential structure for the plain strain problem of an elastic micropolar and isotropic body with pores. The constitutive equations on which the method is applied and is useful are the well-known equations of the elasticity theory for the above-mentioned body. We intend to solve the Kirch problem using the procedure of complex variables. [ABSTRACT FROM AUTHOR]

The reliability of solder joints in electronic packaging was investigated by finite element analysis (= FEA), focusing on the effects of intermetallic compound (= IMC) layers and voids. The results showed that changes in the elastic modulus of the IMC layer of around 20 % did not significantly affect solder joint life. This means that when the modulus of elasticity changes, it is not only the change in modulus that is considered, but also the change in creep properties. In addition, the FEA evaluation of voids underscores the importance of considering equivalent creep strain and cautions against relying solely on the FEA results when void locations do not coincide with maximum equivalent creep strain values. Currently, it is difficult to predict the tendency of voids to affect solder creep life based on FEA analysis results alone. A limitation is that if voids are present in the solder not at the IMC interface, the solder creep life may be underestimated. This study contributes to a better understanding of the complex thermal-fatigue life that solder joint reliability in electronic packaging. [ABSTRACT FROM AUTHOR]

The present article is concerned with the reflection of plane harmonic waves in a nonlocal micropolar thermoelastic medium having void pores in the context of dual-phase-lag and Lord-Shulman models. Two sets of coupled shear waves and three sets of coupled longitudinal waves are shown to exist. When a coupled longitudinal displacement wave is made incident, the reflection coefficients of the various reflected waves and their respective energy ratios are computed analytically and the numerical computation is carried out with the help of MATLAB software. For a particular model, the influence of nonlocal, voids and micropolar parameters on the variations of reflection coefficients and energy ratios of various reflected waves is presented graphically. It is verified that during reflection phenomenon, the sum of energy ratios is equal to unity at each angle of incidence. A comparison between the dual-phase-lag model and Lord-Shulman model is also depicted graphically. [ABSTRACT FROM AUTHOR]

Old and abandoned mine workings become inaccessible with time owing to safety issues thereby demanding insight review of strata overlying such areas. Electrical Resistivity Tomography (ERT) survey was carried out at locations within Kajora area of Eastern Coalfield Limited (ECL) in Raniganj coalfield, India to assess the present strata condition for the proposed high voltage electric transmission layout. Parallel 2D ERT profiles were carried out with 20 m offset covering the study area. Considering the sensitiveness in horizontal direction i.e., identification of vertical structures, the Dipole-Dipole array methodology was implemented. The acquired data sets were filtered and processed using Prosys-II software. L-curve criteria for misfit data was used for proper interpretation of subsurface features. Non-linear least-squares regularized optimization method and 3D ERT volumetric model were performed by combining 2D ERT parallel profiles data sets for better resolution of underground old mine working and accurately map the status of mine workings. High resistivity magnitude ranging between 200 Ωm to 1600 Ωm indicated intact bedrock and solid pillar. Depillared workings area (either dry-filling or air-filled) was identified through anomalous high resistivity magnitude of more than 1600 Ωm. The data generated were also validated with underground working plan and available borehole data. Combination of 2D ERT and 3D ERT techniques against each profile was found to be effective for detection of strata condition for safe installation of terrestrial high voltage electric transmission towers. [ABSTRACT FROM AUTHOR]

The production of high-performance carbon fibers relies heavily on the structural transformations of polyacrylonitrile (PAN) fiber during processing. In this article differential scanning calorimetry (DSC), synchrotron small-angle X-ray scattering (SAXS), and synchrotron wide-angle X-ray diffraction (WAXD) were used to study the changes of the thermal properties, voids and crystal structure of the PAN precursor fibers on industrial lines during the continuous processing stages, i.e., after the treatment in the coagulation bath, after stretching in boiling water and after stretching in high-temperature steam. The findings of this study suggest that after boiling water stretching the molecular chain motion of the PAN precursor fiber weaken, resulting in the expansion of the voids. After high-temperature steam stretching the voids became elliptical and oriented in the stretching direction. Although the boiling water stretching process partially damaged the (100) crystal planes of the PAN precursor fibers, it does not hinder their overall crystalline structure. The high stretching ratio primarily affected the orientation of the molecular chains. This orientation, even in the context of partial crystal plane disruption, further promoted the crystallization of the (100) crystal planes in the fibers. These experiments explored the correlation between the processing technology and fiber structure transformation of PAN-based carbon fibers, resulting in producing a guide for the preparation of high-performance carbon fibers with fewer defects. [ABSTRACT FROM AUTHOR]

Propagation of Rayleigh-type waves is investigated in a half-space composed of nonlocal micropolar thermoelastic material containing void pores. Dispersion relation is derived for a mechanically stress-free and thermally insulated boundary surface of the half-space. The particle motion during the propagation of the waves is found to follow elliptical path. Numerical computations for a specific material are performed to analyze the characteristics of propagating Rayleigh-type waves in detail. Comparison between the phase speed and corresponding attenuation coefficient in some particular cases is also carried out. The effect of various parameters on the characteristics of waves in question is also studied. [ABSTRACT FROM AUTHOR]

The response of elastic waves upon encountering the boundary between two elastic media is investigated in the present work. Whereas the top medium is thermoelastic isotropic porous, the below medium is thermoelastic rotating porous diffusive. There is an uncoupled transmitted SV -wave propagating through the medium, and the lower medium is rotating with some fixed angular frequency. When the incident wave hits the boundary, it produces four transmitted waves and five coupled quasi-reflected waves. The system is divided into longitudinal and transverse components using the Helmholtz decomposition theorem. Analytical computations of speed and reflection coefficients for transmitted and reflected waves are performed using LS theory. The outcomes are graphically represented for a particular material subject to nonlocal and fractional-order influences. Wave characteristics, such as speed and reflection coefficients for transmitted and reflected waves, are plotted versus angular frequency and angle of incidence using MATLAB programing. The conservation of energy has also been verified. In the absence of rotation, hall current, voids, viscoelasticity, and diffusion in the medium, the previous results in the literature are obtained. [ABSTRACT FROM AUTHOR]

Abstract This paper aims to obtain solutions in terms of the complex potential structure for the plain strain problem of an elastic micropolar and isotropic body with pores. The constitutive equations on which the method is applied and is useful are the well-known equations of the elasticity theory for the above-mentioned body. We intend to solve the Kirch problem using the procedure of complex variables.

This paper addresses a significant research gap in the study of surface waves propagation in a nonhomogeneous, within a magneto-thermoviscoelastic material of higher order, initial stress, rotation, gravity effects and voids. This study provides analytical solutions for surface waves propagating through a medium consisting of a magneto-thermoelastic material with voids under the rotation, electro-magnetic field, gravity field and initial stress. The analytical solutions are derived for the displacement components, volume fraction, temperature to Stoneley and Rayleigh waves are computed numerically and presented graphically considering the external parameters impact. Furthermore, this investigates how magnetic field, voids, gravity, initial stress and fiber-reinforced parameters influence these wave phenomena. This investigation provides valuable insights into the synergistic dynamics among electric constituents, voids, Stoneley and Rayleigh waves propagation, enabling advancements in sensor technology, augmented energy harvesting methodologies, and pioneering seismic monitoring approaches. For certain materials, numerical simulations are provided and graphically displayed. The results of this study reveal several unique cases that significantly contribute to the understanding of Rayleigh and Stoneley waves propagation within this intricate material system, particularly in the presence of voids.

Background and purpose: To achieve a successful root canal treatment, it is necessary to have a sealer with ideal characteristics that seal the permanent filling of the tooth canal. Over time, various sealers with different compositions have been introduced to increase the obturation quality of tooth root canals, and many studies are still ongoing to find the ideal sealer. This study aims to evaluate the obturation quality of Endoseal MTA sealer based on the void and spreader track in the root canal using intraoral digital radiography (PSP) and compare it with Adseal and MTA Fillapex. Materials and methods: This laboratory study was conducted on 36 central maxillary single-canal permanent human teeth with the same shape and in the pre-clinic of the dental school of Mazandaran University of Medical Sciences. Root canal preparation was done with the Denco rotary system up to size F3 according to the manufacturer's instructions. During preparation, sodium hypochlorite 5.25% was used for washing, and finally EDTA 17% and sodium chlorite 5.25% were used to remove the smear layer. The teeth were dried with a paper cone. The samples were randomly divided into 3 groups and were filled with gutta-percha and sealers; MTA Fillapex, Endoseal MTA, and Adseal by lateral compaction method using Master Cone 35 and cone 20. After the sealers were set completely for 24 hours, PSP imaging was done with a parallel technique, buccolingually and mesiodistally, from the root canal of the teeth, and the presence of void and gaps in the form of spreader track in the three apical, middle and coronal regions, was evaluated with 3 independent observers. The data were evaluated with chi-square or Fisher's exact test, and items less than 0.05 were considered significant. Results: In the current study, the obturation quality of MTA Fillapex, Endoseal MTA, and Adseal sealers was investigated on 36 teeth based on void and gap in the form of spreader track. These evaluations were done according to the direction and location of the sealers. In these evaluations, Adseal sealer had the lowest and MTA Fillapex had the most prevalence of spreader track prevalence, although these differences were not significant based on the chi-square test and there was no significant difference between the prevalence of Spreader track among the three sealers. The void was observed only in the Endoseal group in coronal (mean: 0.5) and apical (mean: 0.7) areas. The results of the Chi-square test showed that there was no significant relationship between the prevalence of void with coronal, middle, and apical sites in Endoseal (P

AbstractThis paper investigates Love-type wave propagation in a multilayered, elastic, prestressed solid half-space with voids. Using the Haskell matrix method, the dispersion relation is derived for a stress-free boundary surface. Two distinct dispersive fronts of Love-type waves, propagating at different speeds, are identified. One behaves like waves in a prestressed elastic half-space, while the other is novel due to voids. Analytical expressions for three-layered and two-layered models are provided. Graphical representations compare the dispersion curves, highlighting differences and dependencies. The study explores how void parameters, initial stress, and layer thickness influence phase velocity, with applications in various engineering fields. [ABSTRACT FROM AUTHOR]

Highlights 2.5D woven composite material inevitably produces void defects in its production process, which will seriously reduce its mechanical properties and reduce its service life. In this paper, the effects of void defects on the mechanical properties of 2.5D woven composites were studied by multi‐scale analysis. An improved Halpin‐Tsai semi‐empirical model is proposed to calculate the elastic properties of yarns with porous defects and verified by finite element method. A microscale representative volume unit (RVE) for predicting the elastic constants of composites with pore defects is established. Theoretical analysis and finite element analysis were used to verify the micro scale, and finite element analysis and experiment were used to verify the micro scale. The effect of porosity on the elastic properties of micro‐scale RVE was studied in detail. The results show that the model is reasonable and accurate in predicting the mechanical properties of yarns and composites. In addition, the effect of porosity on the mechanical properties of 2.5D woven composites is significant. An improved Halpin‐Tsai semi‐empirical model is proposed, which makes the microscale theoretical analysis of 2.5D woven composites better consistent with the finite element analysis. The void position obstructs the stress transfer of the matrix, and the stress concentration phenomenon also occurs. The void content has an effect on the mechanical properties of composites at both micro and micro scales. [ABSTRACT FROM AUTHOR]

Photothermal transport process and voids in solids are important phenomena in a variety of engineering approaches and scientific disciplines. For this purpose, the photothermal theory is being utilized to study the coupling between elastic waves and plasma waves in a semiconducting medium with voids. The basic governing equations for photothermal waves are derived in the framework of hyperbolic two-temperature theory and Green–Lindsay model. Normal mode analysis method is used to obtain the physical field distributions under investigation. A moving thermal load is applied at the outer free surface of the medium to obtain the complete solution. Expressions are calculated numerically for silicon (Si) material and presented to observe the variations of the field quantities. The effects of various key parameters on the physical fields are also shown graphically. Special cases that are consistent with the earlier findings have been obtained. Although, numerous studies do exist on the deformation analysis in a photothermoelastic medium under different thermoelasticity theories. However, no research emphasizing thermodynamical analysis of the photothermal transport process in a hyperbolic two-temperature semiconducting medium with voids under the influence of gravity and Hall current has been carried out. This provides us a motivation to study the current research. Chemical engineering, geophysics, earthquake engineering, soil dynamics, high-energy particle physics, nuclear fusion, aeronautic biomechanics, bone mechanics, and petroleum industry are the major application areas of the photothermolelasticity theory. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background and purpose: To achieve a successful root canal treatment, it is necessary to have a sealer with ideal characteristics that seal the permanent filling of the tooth canal. Over time, various sealers with different compositions have been introduced to increase the obturation quality of tooth root canals, and many studies are still ongoing to find the ideal sealer. This study aims to evaluate the obturation quality of Endoseal MTA sealer based on the void and spreader track in the root canal using intraoral digital radiography (PSP) and compare it with Adseal and MTA Fillapex. Materials and methods: This laboratory study was conducted on 36 central maxillary single- canal permanent human teeth with the same shape and in the pre-clinic of the dental school of Mazandaran University of Medical Sciences. Root canal preparation was done with the Denco rotary system up to size F3 according to the manufacturer's instructions. During preparation, sodium hypochlorite 5.25% was used for washing, and finally EDTA 17% and sodium chlorite 5.25% were used to remove the smear layer. The teeth were dried with a paper cone. The samples were randomly divided into 3 groups and were filled with gutta-percha and sealers; MTA Fillapex, Endoseal MTA, and Adseal by lateral compaction method using Master Cone 35 and cone 20. After the sealers were set completely for 24 hours, PSP imaging was done with a parallel technique, buccolingually and mesiodistally, from the root canal of the teeth, and the presence of void and gaps in the form of spreader track in the three apical, middle and coronal regions, was evaluated with 3 independent observers. The data were evaluated with chi-square or Fisher's exact test, and items less than 0.05 were considered significant. Results: In the current study, the obturation quality of MTA Fillapex, Endoseal MTA, and Adseal sealers was investigated on 36 teeth based on void and gap in the form of spreader track. These evaluations were done according to the direction and location of the sealers. In these evaluations, Adseal sealer had the lowest and MTA Fillapex had the most prevalence of spreader track prevalence, although these differences were not significant based on the chi-square test and there was no significant difference between the prevalence of Spreader track among the three sealers. The void was observed only in the Endoseal group in coronal (mean: 0.5) and apical (mean: 0.7) areas. The results of the Chi-square test showed that there was no significant relationship between the prevalence of void with coronal, middle, and apical sites in Endoseal (P<0.05). Conclusion: No difference was observed between the three sealers in the voids and gaps in the root canal. Based on the results of this study, the obturation quality of the above three sealers isn't different from each other. Although the presence of more void in Endoseal MTA sealer was not significant, it can indicate that the handling of this material is difficult, on the other hand, according to the manufacturer's recommendation, this sealer is recommended for single cone method and is not suitable for use in lateral compression method. [ABSTRACT FROM AUTHOR]

In this paper we approach the linear mixed problem with initial and boundary values for a Cosserat body which is elastic and has pores. We coupled the equations characterizing the pores evolution with basic equations that describing the elastic deformations of the Cosserat body. The coupling is done by means of predetermined coefficients. To prove the continuous dependence of the solutions, we introduce an adequate measure which is useful in obtaining of some estimations with respect to the gradient of elastic deformations and regarding the gradient of a specific the application, introduced to characterize the behavior of the pores. [ABSTRACT FROM AUTHOR]

Cosmic voids identified in the spatial distribution of galaxies provide complementary information to two-point statistics. In particular, constraints on the neutrino mass sum, ∑ m ν , promise to benefit from the inclusion of void statistics. We perform inference on the CMASS Northern Galactic Cap sample of the third-generation Sloan Digital Sky Survey/Baryon Oscillation Spectroscopic Survey (BOSS) with the aim of constraining ∑ m ν . We utilize the void size function, the void–galaxy cross power spectrum, and the galaxy auto power spectrum. To extract constraints from these summary statistics we use a simulation-based approach, specifically implicit likelihood inference. We populate approximate gravity-only, particle-neutrino cosmological simulations with an expressive halo occupation distribution model. With a conservative scale cut of k max = 0.15 h Mpc − 1 and a Planck-inspired Lambda cold dark matter prior, we find upper bounds on ∑ m ν of 0.43 and 0.35 eV from the galaxy auto power spectrum and the full data vector, respectively (95% credible interval). Relaxing the scale cut to k max = 0.2 h Mpc − 1 , we find 0.28 and 0.32 eV. Generally, void statistics appear to add modest but nonzero information beyond the auto power spectrum. We also substantiate the usual assumption that the void size function is Poisson distributed. [ABSTRACT FROM AUTHOR]

Parts with interior voids created by the LPBF process are known to have the potential to cause fracture when subjected to mechanical loading. In this research, the key process parameters such as laser thickness (LT), scanning speed (SS), and laser power (LP) were taken into consideration to avoid the void formations which was the major reason for affecting the structural integrity. So, void formations (V), ultimate tensile strength (UTS) and reduced modulus (RM) were considered as the response parameters in this study. The entropy-associated weighted aggregated sum product assessment (WASPAS) approach was implemented to examine the favorable conditions which substantiated that the LT is the most influential parameter in nucleation of voids. The verification experiments prove that the void formation was reduced by 98.6% and the UTS and RM were enhanced by 52.17 and 31.7%. [ABSTRACT FROM AUTHOR]

This article's objective is to investigate the effect of Hall current on the propagation and reflection of thermoelastic waves through viscoelastic nonlocal fractional order rotating porous isotropic solid. The system is split up into longitudinal and transverse components using the Helmholtz vector rule. Four coupled plane waves are seen to exist, each moving through the medium at a different speed. It is found that all of the waves are dispersive as they depend on the angular frequency. The plane wave characteristics like amplitude ratios and velocity are computed. Under suitable boundary conditions, numerical calculations of the energy and amplitude ratios of various reflected waves are performed using MATLAB software. The speed and amplitude ratios of the waves, qP, qT, qSV, and qV are calculated in the context of LS theory. The results are further plotted for a specific material under the effect of the nonlocal, viscoelastic, fractional order, and Hall current parameters. The earlier findings in the literature are obtained as special case in the absence of rotation, viscoelastic, Hall current parameters and porous voids. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the ability of a modified passive deflation needle to reduce the apical voids during the intra-canal iRoot SP sealer injection. A modified passive deflation injection needle was designed. Forty 20°-curved and twenty S-shaped single-canal resin block models were allocated into six groups. Each group was mechanically prepared to #25/04 or #25/06 file; then the root canals were injected with iRoot SP sealer using a modified needle or a normal plastic needle. Radiographs were taken to measure the length of apical void in each specimen. Similarly, twenty single-canal extracted premolars were collected and randomly divided into four groups. Each group was prepared to #25/04 or #25/06 file; then the root canals were injected with iRoot SP sealer using a modified needle or a normal plastic needle. Roots were then scanned using micro-computed tomography (micro-CT), and the volume of voids in root canals was analyzed and compared among groups. Statistical analysis demonstrated that the length and the volumetric percentage of voids were much lower in the modified needle group in both resin block root canal models and extract teeth than the normal plastic needle group (P < 0.05). The modified passive deflation needle can efficiently reduce apical voids during the intra-canal iRoot SP sealer injection. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

AbstractHollow-core precast prestressed reinforced concrete (HCPPRC) slabs have been widely available since the 1980s in different structures due to many advantages. Since no shear reinforcement is arranged in HCPPRC slabs before casting, concrete itself provides the shear resistance, especially in the zones close to the supports, which are the most popular regions for shear failure. This experimental study aims to investigate some shear strengthening techniques for HCPPRC slabs, including using carbon fiber reinforced polymer (CFRP) sheets, concrete topping, filling 50% of the slab voids in shear zones with concrete, filling all shear zone voids with concrete, steel through anchors in shear zones, and mixing between filling 50% of the slab shear zone voids in addition to using steel anchors. The experimental program consists of two control specimens and six shear-strengthened specimens that were tested using two-line loads up to failure. Cracking load, cracking deflection, ultimate load, maximum deflection, and failure mode are recorded and discussed for all specimens. The results show that filling 50% and 100% of shear voids with concrete increases slab concrete strength by about 79% and 61.45%, respectively, while using steel through anchors decreases slab concrete strength. Moreover, filling 50% of the shear voids is the best technique for strengthening the shear capacity of HCPPRC slabs due to increasing the cross-section area of the slab’s shear strength. In contrast, using screws with nuts only is not preferred for shear strengthening of HCPPRC slabs.

The continuous drive friction welding (CDFW) stands out for its low energy consumption within the welding realm. Polyetheretherketone (PEEK) represents a high-performance engineering thermoplastic, falling under the polyaryletherketone family. Renowned for its outstanding mechanical, thermal, and chemical attributes, PEEK finds utility across a diverse array of industries. However, the discovery of numerous voids at the weld interface has revealed limitations in the mechanical properties of PEEK welded samples. This study introduces an innovative approach named progressively increased welding area (PIWA) method, to mitigate voids within the weld interface. In general, the Taguchi method was used to optimize the process parameters of CDFW of dissimilar PEEK round rods to reduce random efforts by the trial-and-error method. It was found that the proposed PIWA method can definitely enhance the bending strength of rotational friction welded samples due to reduction of voids inside the weld interface. The optimal process parameters for the CDFW with the PIWA method involve a rotational speed of 2500 rpm, a cone angle of 120°, a cone top width of 8 mm, and a feed rate of 0.1 mm/s. The most influential factor affecting the bending strength of the PEEK welded samples is the feed rate, followed by cone angle, rotational speed, and cone top width. Specifically, the contribution ratios for feed rate, cone angle, rotational speed, and cone top width are about 71 %, 20 %, 7 %, and 2 %, respectively. The confirmation tests showed that the bending strength of the PEEK welded samples using optimal process parameters can be increased by approximately 68 % compared with the maximum bending strength of 180 MPa using the conventional method with a cone angle of 180° The proposed PIWA method has industrial applicability and practical value because this technique can enhance the mechanical properties of PEEK welded samples under low environmental pollution and energy consumption.

A sustainable concrete solution was developed by partially replacing aggregates and cement with lightweight plastic aggregates (LWPA) and bagasse ash, respectively. Three types of mixes were studied: (i) concrete with 10-30% cement replaced by bagasse ash (BA), (ii) Bagasse ash concrete mix with scrap steel fiber, and (iii) Bagasse ash concrete with scrap fiber and 10-50% lightweight aggregate. The addition of bagasse ash positively influenced the fresh properties of concrete. However, workability decreased by 56% with the incorporation of scrap fibers and lightweight aggregate compared to the control mix. Slump values reduced in concrete mixes containing plastic aggregate (PA) due to mortar accumulation in voids within the hollow aggregate, significantly diminishing workability. The density of concrete decreased with bagasse ash and lightweight aggregate inclusion, aiding in reducing structural dead weight. However, the strength decreased notably with 30% replacement using hollow lightweight plastic aggregate. Voids in concrete specimens increased with LWPA percentage. Observations from fresh and hardened concrete tests suggest that plastic aggregate, bagasse ash, and scrap fiber can effectively replace up to 20% of gravel aggregate.

Objective: To identify the potential factors that induce procedural errors during posterior proximal resin composite restorations placed by dental students. Materials and Methods: This retrospective study evaluated 803 bitewing radiographs of posterior proximal resin composite restorations placed by dental students at Imam Abdulrahman bin Faisal University. Atypical radiographic signs of failure were screened, and different patient-, operator-, and clinical-related factors were recorded. Chi-square test was used to examine the relationship between procedural errors and recorded factors. Stepwise adjusted logistic regression model was performed to identify predictors of procedural errors. Results: The most observed errors were internal gaps at the bonding interface and internal voids. Molars had 0.39 the risk of internal voids (odds ratio [OR] = 0.39; confidence interval [CI] = 0.25–0.60; P = 40 years of age had 1.79 the risk of overhang compared to younger patients (OR = 1.79; CI = 1.04–3.11; P =

Additive manufactured Ti6Al4V printed via powder bed fusion (laser or electron beam melting) is one of the most researched alloys for AM applications. However, even under optimized printer conditions, defects can still exist. This paper provides a brief review from industry literature on PBF printed Ti6Al4V microstructure, the powders used in the printing process, defects associated with the process, and unwanted microstructural conditions. The review is intended to provide general information and targets those new to the PBF process. Defects such as porosity, contamination, chemistry variances, balling, sputtering, cracks, lack of fusion, surface roughness, residual stresses, and their reported sources are discussed. Brief notes on defect influences on fatigue, and multi-laser related defects were provided for general awareness. [ABSTRACT FROM AUTHOR]

All produced spaces are curious since they could, by definition, be different. Atriums—double height or greater vertical voids typically to be found in skyscrapers' lobbies—are an interesting illustration of this general contention. An internal feature of super-tall architecture the world over, the atrium flourishes in parts of cities where land value is high and given that atria could be occupied with directly rentable space this is an ostensibly puzzling affinity. Drawing primarily on the ideas of Henri Lefebvre and Walter Benjamin, this paper suggests that the presence of atria in major commercial—and increasingly public—buildings grows from oblique attempts to generate surplus value. Paradoxically, it is the voided space of the atrium that explains this strategy. My argument is that voids of open space can actually increase the value of objects, bodies, and practices that are assembled in and around them; paradoxically 'emptiness' itself can be monetised in a context of rentier capitalism. Defamiliarising the atrium, which is a distinctive and singular architectural feature of this moment, suggests a wider research agenda for those interested in critical analysis of the contradictory spaces that are produced when capital builds. [ABSTRACT FROM AUTHOR]

A hybrid multiscale model consisting of two coupled modules is used to study the effect of irradiation temperature on the kinetics of the formation of swift heavy ions tracks in silicon carbide (6H-SiC). Excitation of the electronic and atomic subsystems of the material is simulated using the Monte Carlo TREKIS-3 code. The profile of energy transferred to the atomic lattice is used as the initial conditions for molecular-dynamics simulations (using the LAMMPS package) of structural changes in the material near the trajectory of the swift heavy ion. Using the example of Bi-ion irradiation with an energy of 710 MeV, it is found that increasing irradiation temperature leads to an increase in the energy density transferred to the lattice. This induces rapid disordering of the core structure of the track at timescales on the order of 0.25 ps. At irradiation temperatures below 1800 K, subsequent recrystallization of the amorphous region within the cooling track leads to complete restoration of the material structure. At temperatures above the threshold of 1800 K, mass transfer, determined by the ejection of dislocations from the track core, results in the formation of nanoscale voids with a diameter of approximately 3 nm along the ion trajectory. The simulation results are useful for assessing the radiation resistance of silicon carbide under extreme irradiation conditions and for formulating ideas and designing new experiments on high-temperature SiC irradiation. [ABSTRACT FROM AUTHOR]

Copyright of Acta Odontologica Latinoamericana: AOL is the property of Acta Odontologica Latinoamericana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper first we formulate the mixed problem with initial and boundary values in the context of the porous Cosserat thermoelastic bodies micropolar material with voids. WE have included among the independent constitutive variables the derivative with respect to time of the voids (pores) function. Under the conditions in which we imposed average restrictions on the functions used, we formulated and demonstrated the uniqueness of the solution to the mentioned mixed problem and we did a short analysis on the dilatational waves in this kind of media. [ABSTRACT FROM AUTHOR]

Rayleigh-type surface waves propagating in a magneto-elastic half-space containing voids are studied. Dispersion equation is derived under suitably constructed boundary conditions, which involves elastic, electro-magnetic, void parameters and angular frequency, but contains radicals, making it difficult to solve analytically. However, under limiting frequencies, the dispersion equation is analyzed and discussed. The effect of various parameters on phase velocity of propagating Rayleigh-type surface waves is investigated and shown graphically for a particular model. The effect of induced electric field on considered surface waves is also studied and explained. It is shown that the particles near the boundary surface move in an elliptic manner. However, if there is no phase difference between the displacement components, then we have a degenerate case. Some special cases of dispersion relation are also deduced from the present formulation. [ABSTRACT FROM AUTHOR]

Copyright of Railway Investigation & Surveying is the property of Railway Investigation & Surveying Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Vacuum-bag-only (VBO) consolidation of automated fiber placed (AFP) thermoplastic composites can be a cost-effective processing route for large and complex thermoplastic composite structures. This paper explores the possibility of two-step AFP and VBO consolidation of advanced thermoplastic composites. Two commercially available carbon fiber reinforced Poly-Ether-Ketone-Ketone (C/PEKK) thermoplastic tapes were evaluated. Different process parameters were needed for the two material systems. Further, for the first time, an attempt was made to create in-plane air evacuation channels by deliberately introducing gaps between the tapes in the preforms during the placement. In the case of one material system, the VBO consolidation of preforms with and without gaps yielded good consolidation quality with less than 1% voids. In the other case, VBO consolidation of preforms with gaps showed a improved consolidation quality with less than 1% voids than the preform without gaps, indicating that the gaps possibly help accelerate the gas evacuation process. [ABSTRACT FROM AUTHOR]

In current problem, fundamental solution in an isotropic non-local couple stress micropolar thermoelastic solid with voids is investigated. We observed that there are five waves, viz. a set of three coupled longitudinal waves and a set of two coupled transverse waves propagating with different phase velocities. The impact of non-local and void parameters on the penetration depth, specific loss, attenuation coefficient and phase velocity has been studied numerically and graphically with respect to angular frequency. The fundamental solutions of the system of differential equations in case of steady oscillations have been investigated. Particular cases are established and compared with the known results. [ABSTRACT FROM AUTHOR]

Porous materials have been extensively used in electronic communications, aerospace, bio-medicine and petrochemical, etc. due to their attractive attributes such as low relative density, thermal and acoustical insulation and good permeability. Ultrashort laser pulses have a series of unique advantages including high energy density, ultrashort interaction time and high accuracy, which are widely used in the fields of precision machining and microelectronic manufacture. For porous materials heated by an ultrashort laser pulse, revealing the interplay between deformation field and temperature field is crucial to guide their engineering application and optimization design. The present work devotes to investigating the transient response of a porous half-space heated by a non-Gaussian laser beam on its boundary surface based on the newly established linear thermoelastic theory with strain and thermal relaxations. The coupled governing equations are formulated and solved through the Laplace transform and its numerical inversion. The distributions of the non-dimensional temperature, displacement, stress as well as volume fraction field are obtained and illustrated graphically. In calculation, the effects of the thermal relaxation factor, the strain relaxation factor on the temperature field, volume fraction field, displacement field as well as stress field are examined and discussed in detail. [ABSTRACT FROM AUTHOR]

This study investigates the effect of voids on the mechanical response of a carbon fiber reinforced polymer composite with simple finite elements micromechanical analysis. Cure hardening behavior of resin is implemented into the model to calculate the cure shrinkage, coefficients of thermal expansion (CTEs) and residual stresses. It is seen that voids cause more detrimental decrease on longitudinal CTE than transverse direction. Tensile loading to void containing residual stress-induced models show that the increasing void content diminishes the initial failure stress in longitudinal direction. Also, the reduction in transverse tensile strength with increasing voids is consistent with experimental results. [ABSTRACT FROM AUTHOR]