Cavity Depth Research Articles

Micro/Meso‐Porous Double‐Shell Hollow Carbon Spheres through Spatially Confined Pyrolysis for Supercapacitors and Zinc‐Ion Capacitor

AbstractEnergy storage in supercapacitors and hybrid zinc ion capacitors (ZIC) using porous carbon materials offers a promising alternative method for clean energy solutions. The unique combination of hierarchical porous structure and nitrogen doping in these materials has demonstrated significant capacity for energy storage. Nevertheless, the full potential of these materials, particularly the relationship between pore structure configuration and performance, remains underexplored. Herein, a confined pyrolysis strategy based on the polymerization characteristics of polydopamine (PDA) was developed to construction of hollow carbon spheres with microporous/mesoporous dual shell structure. The depth of micropores and cavity can be controlled by adjusting the duration of heat treatment and hydrothermal treatment, in accordance with the decomposition and polymerization characteristics of PDA. Due to the elasticity of this structure, the relationship between the micro/mesoporous depth of the prepared carbon spheres and the energy storage performance in supercapacitors and ZIC is established. Through optimizing the ion transport capacity of carbon spheres and considering the influence of its internal cavity structure on energy storage, the resulting carbon spheres exhibit high specific capacitance of 389 F g−1 in supercapacitor and specific capacitance of 260 F g−1 and excellent stability with 99.3 % retention after 30000 chare/discharge cycles in ZIC.

Prediction of interface morphology formed by the oblique gas jet impinging on a liquid surface

This study presents a theoretical analysis of the oblique gas jet impingement process on a liquid surface, elucidating the evolution of the flow field distribution and the influence of jet parameters on cavity shape dynamics. By integrating surface tension effects, the existing Blanks and Chandrasekhara model was refined to develop an advanced predictive model for cavity morphology. The theoretical framework was substantiated through numerical simulations and corroborated with experimental measurements of cavity dimensions, captured using state-of-the-art machine vision technology. The findings reveal a consistent trend in cavity dimension variations: an increase in the cavity surface width with the elevation of the impinging angle from the vertical and an escalation in gas jet velocity. Conversely, a reduction in the impinging angle coupled with an increase in jet velocity leads to a deeper cavity. To enhance the predictive accuracy, the model underwent iterative optimization, incorporating experimental data and accounting for jet parameters. The refined model demonstrated achieved a maximum error of 0.135 mm and a minimum error of 0.03 mm, providing reliable forecasts of cavity depth, which is pivotal for applications in fluid dynamics and related engineering fields.

Design optimization of a new cavity receiver for a parabolic trough solar collector

The most important parameter affecting the optical efficiency, the upper limit for an overall efficiency of parabolic trough solar collector (PTC), is the net absorbed heat rate by receiver on which solar beam radiation is concentrated. The objective of this study is to propose and optimize a new cavity receiver used in PTC for increasing optical efficiency. Three different geometries (triangle, rectangle and polygon), aperture widths, heights and positions of cavity receiver are taken as optimization parameters. A design of experiments (DoE) approach is used to evaluate the effects of these parameters on the absorbed radiation heat rate by receiver at the same time. SolTrace is used to investigate the effects of these parameters by optical analysis. The results indicate that the optimum cavity geometry is polygonal, and the cavity depth and aperture both are equal to 0.05 m. Moreover, it is found that the most effective parameter is the position of the cavity receiver, and the optimum position is at the focal line of the parabolic concentrator. The highest absorbed radiation rate by the cavity receiver and the optical efficiency of the PTC are equal to 3241.99 W and 81.05 % respectively for the optimum cavity receiver design.

Technology and quality of the consumable electrodes, received by semi-continuous casting, for vacuum-arc remelting

he process of vacuum arc melt down is greatly dependent on the quality of the electrodes used. Electrodes of highly alloyed steels are negatively affected by the great amount of films, inversions, subcortical bladders and others; they are being cleansed and sanded down, this leads to substantial waste of expensive metals. For this purpose in the process of casting of highly alloyed steels a great deal of importance is put upon the creation of a method, which could be used for the purpose of protecting the metal from secondary oxidization. The increase in quality of semi-continuous cast electrodes and the removal of previously mentioned defects can be achieved with the use of slag mixtures, which posses thermo-insulating properties and can be partially melted down by the heat which is produced by the liquid metal, that fills the catalyzer. The goal of this project was to research the influence of thermal-insulating slag-producing mixtures on the quality of semi-continuous cast electrodes in the process of vacuum arc melt down in comparison to the ones that were casted under the exothermic mixtures, their effect on the process of melting and the quality of vacuum arc melt down ingots. In this project there were researched such topics as the componential, chemical composition, the physical properties of the thermo insulating mixture and the physical-chemical properties of the melt of said mixture. We researched the quality of the surface of the electrodes, the macrostructure, the chemical uniformity, density, content and the dispersal of non-metallic and gas-like additions on the transverse templates after the main cutting of 600mm, the stability of flow of the vacuum melt down, the quality of the vacuum arc melt down ingots and the rolled sheets made from the arc welded ingots. The geometry of the electrodes, casted under the thermal insulating mixture, is in order with the requirements: the degree of distortion of the profile, in comparison with the one achieved with the use of exothermic mixture, was reduced in half. The macrostructure of the electrodes is dense, without any visual defects. The losses of the metal in the process of sanding during the preparation for the vacuum arc melting were reduced by 2 times in comparison with the casting under exothermic mixture. The depth of the shrinkage cavity is reduced approximately by 12%, the form of the cavity takes the form of a “cup”. The amount of non-metallic and gas-like additions is being significantly reduced. The amount of electrodes that are being recast without issues (the creation of slag, ionization, ionization with slag), during the transition from exothermal to thermal insulating on average is reduced by 3–3,5 times. The purity of metal of vacuum arc melt down electrodes, that are casted under thermo insulating mixture, is in accordance with the requirements; the mechanical properties of rolled vacuum arc ingots exceed the norms of technical conditions.

Mathematical Modeling on the Multiphase Flow during Top–Bottom Combined Blowing Basic Oxygen Furnace Steelmaking Process

A 3D mathematical model on the multiphase flow and splashing phenomenon in a 210 t Basic oxygen furnace converter is established. The turbulent multiphase flow of the molten steel, slag, and oxygen is simulated by the combined realizable k−ε model and volume of fluid model. The trajectory of argon bubbles and the interaction between the molten steel and argon is simulated by the two‐way coupled Lagrangian discrete phase model. Effects of the lance height and bottom‐blowing gas flow rate on the multiphase flow and splashing phenomenon are investigated. The results indicated that the cavity depth is decreased from 0.45 to 0.36 m when the lance height increases from 1700 to 2300 mm. The cavity depth is not significantly affected by the bottom‐blowing argon flow rate with the 44 000 m3 h−1 top‐blowing oxygen flow rate and 1700 mm lance height. The increased lance height resulted in a decrease in splashing. When the oxygen lance height increases from 1700 to 2300 mm, the amount of the splashed molten steel decreases from 3774.3 to 1953.0 kg.

Sound absorption performance of honeycomb metamaterials Inspired by Mortise-and-Tenon structures

To address the limitations of traditional honeycomb sandwich structures in attenuating mid to low-frequency sounds, particularly in configurations with minimal thickness and weight, this study introduces an innovative honeycomb acoustic metamaterial incorporating the traditional Chinese mortise-and-tenon joint. We systematically investigate the acoustic absorption characteristics of the modified honeycomb structure through theoretical analysis, empirical validation, and numerical simulations. Our experimental setup maintained consistent geometric parameters across all trials and demonstrated that the resonance frequency of the modified honeycomb structure decreased by 10 % relative to its conventional counterpart. We conducted detailed analyses on the influence of micropore positioning, tenon geometric dimensions, and micropore diameters on the acoustic performance. Notably, elongating the tenon from 2 mm to 6 mm resulted in a 15 % reduction in resonance frequency, whereas increasing the micropore-to-tenon distance from 0 mm to 4 mm led to a 30 % increase. The integration of the mortise-and-tenon joint significantly enhances the mid to low-frequency sound absorption performance of the honeycomb panels. This improvement is achieved while preserving the structural benefits of low panel thickness and shallow cavity depth, alongside simplified processing of micropores. Our findings elucidate a promising approach to augmenting the acoustic properties of lightweight structural materials, thereby extending their application potential in noise control engineering. This study not only contributes a novel perspective to the design and optimization of acoustic metamaterials but also highlights the potential for integrating traditional architectural techniques with modern material science to enhance noise control solutions.

Postoperative sensitivity of composites using novel Bacillus subtilis nanofortified adhesives: a triple-blind study

Nanotechnologyis the art and science of dealing with nanoscale particles. This has transformed contemporary dental practices through myriad contributions to biomaterial science. Titanium dioxide nanoparticles procured from Bacillus subtilis, an eco-friendly and biogenic source, can significantly magnify the physiochemical attributes of dental materials. However, postoperative sensitivity is a major drawback of composite restorations. The incorporation of these nanoparticles into dental adhesives can greatly benefit clinical dentistry by resolving this issue. This trial aimed to evaluate the effectiveness of a novel titanium dioxide nanofortified adhesive on the postoperative sensitivity of composite restorations.MethodsThis triple-blind, parallel-group randomized controlled trial was conducted at the Department of Operative Dentistry and Endodontics, School of Dentistry, Islamabad, from May 15, 2023, to November 25, 2023. Participants (n = 60) with Class I and II primary carious lesions with a minimum cavity depth of 3–5 mm were randomly assigned to two groups (n = 30). After obtaining informed consent, the restorative procedure was accomplished using a minimally invasive approach and etch-and-rinse adhesive strategy. In group A, a nanofortified adhesive was used for composite restoration, whereas in group B, an adhesive without nanoparticles was used. Postoperative sensitivity was evaluated using the Visual Analog Scale (VAS) score at follow-up periods: of one day, one week, two weeks and one month. A Chi-square test was used to compare postoperative sensitivity between the two groups. The level of significance was set at p < 0.05.ResultsA noteworthy association was observed between sensitivity and the group variable at all four evaluation periods: after one day (p = 0.002), 1 week (p = 0.002), 2 weeks (p = 0.007) and one month. In conclusion, participants who underwent restorative intervention using titanium dioxide nanoreinforced adhesives reported a notable reduction in sensitivity at all time intervals. Hence, the occurrence and severity of postoperative sensitivity are significantly reduced using Bacillus subtilis-procured nanofortified adhesives as compared to conventional adhesives without nanoparticles.Trial registrationThis trial was retrospectively registered at ClinicalTrials.gov (ID: NCT06242184) on 03/02/2024. All procedures involving human participants were performed in conformance with this protocol.

Evaluating the accuracy of CEREC intraoral scanners for inlay restorations: impact of adjacent tooth materials

BackgroundThe accuracy of intraoral scanning is critical for computer-aided design/computer-aided manufacturing workflows in dentistry. However, data regarding the scanning accuracy of various adjacent restorative materials and intraoral scanners are lacking. This in vitro study aimed to evaluate the effect of adjacent restorative material type and CEREC's intraoral scanners on the accuracy of intraoral digital impressions for inlay cavities.MethodsThe artificial tooth was prepared with an occlusal cavity depth of 2 mm, a proximal box width at the gingival floor of 1.5 mm, and an equi-gingival margin extended disto-occlusally at the transition line angle on both the lingual and buccal sides for an inlay restoration. The adjacent teeth were veneered with crowns made of gold and zirconia, and an artificial tooth (resin) was utilized as the control group. The inlay cavity and adjacent teeth (Gold, Zirconia, and resin) were scanned 10 times using Chairside Economical Restoration of Esthetic Ceramics (CEREC) Primescan (PS), Omnicam (OC), and Bluecam (BC). A reference scan was obtained using a laboratory scanner (3-shape E3). Scanning was performed according to the manufacturer's instructions, including powder application for the BC group. Standard tesselation language files were analyzed using a three-dimensional analysis software program. Experimental data were analyzed using a two-way analysis of variance and the Tukey’s post-hoc comparison test.ResultsThe restorative materials of the adjacent teeth significantly affected the accuracy of the intraoral digital impressions (p < .05). The zirconia group exhibited the highest trueness deviation, followed by the resin and gold groups, with each demonstrating a statistically significant difference (p < .05). The resin group demonstrated the highest maximum positive deviation and deviation in precision. Gold exhibited the lowest average deviation value for trueness compared with those of the other adjacent restorative materials. Intraoral scanner type significantly influenced the trueness and precision of the scan data (p < .05). The average deviation of trueness according to the intraoral scanner type increased in the following order: BC > PS > OC. The average deviation in precision increased in the following order: PS>OC>BC (p < .05).ConclusionThe restorative materials of the adjacent tooth and the type of intraoral scanner affect the accuracy of the intraoral digital impression. The trueness of the digital images of the BC group, obtained by spraying the powder, was comparable to that of the PS group. Among the adjacent restorative materials, zirconia exhibited the lowest trueness. In contrast, PS demonstrated the highest precision among the intraoral scanners, while resin displayed the lowest precision among the adjacent restorative materials.

Impact of single and two successive droplets on a liquid pool

The interaction between droplets and a liquid pool is a widely observed fluid phenomenon with significant relevance to various industrial applications. This study numerically investigates the impact of both a single droplet and two successive droplets on a liquid pool with a fixed thickness. Particular emphasis was focused on the evolution of cavity depth and width during the deformation process. For single droplet impacts, the cavity depth exhibits linear growth with time in the early stage, consistent with predictions based on energy balance. This growth is independent of the Weber number (We) within the explored range of 96&amp;lt;We&amp;lt;345. Similarly, the cavity width shows weak dependence on the Weber number during early development, deviating and reaching a maximum width at later times. The maximum cavity width follows a power-law relationship with the Weber number, with a 0.5 exponent. In the case of successive droplet impacts with small initial separation, cavity depth also evolves linearly with time in the early stage but over an extended period. This prolonged growth is attributed to droplet merging, resulting in an effectively larger merged droplet. However, for successive droplets with large separation, the two linear growth stages exhibit intermittent interruptions due to the second impact occurring at a later time. The variation in cavity width due to different initial spacings between two successive droplets still exhibits similarity until a larger spacing causes a change in the rate of cavity width development.

In situ acoustic characterization of a perforated panel on a cavity by means of PU measurement and model fitting

The in situ characterization of materials is a crucial challenge in room acoustics, as laboratories measurement cannot always be applied in consultancy practices. In particular, there is a lack of method to characterize in situ systems with perforated facings, which are commonly encountered systems in room acoustics. In this paper, the in situ characterization of a rigidly-backed porous material behind a rigid perforated facing by means of pressure–velocity measurements is presented. The method includes an inverse impedance model fitting based on measurement in a limited frequency range. The applicability of this method was studied by measuring a variety of perforated facings, whether in front of an air cavity or backed by a porous layer, and comparing the obtained impedance model parameters to reference values. Good agreement was observed between the retrieved parameters and the references, with the errors in all retrieved parameters moving mass, facing thickness, cavity depth, porous layer thickness and porous layer flow resistivity not exceeding 15%.

Sound absorption properties and mechanism of multi‐layer micro‐perforated nanofiber membrane

AbstractAiming at achieving low‐frequency and broadband sound absorption under the premise of light and thin layers, in this paper, polyvinyl butyral (PVB) nanofiber membranes were micro‐perforated and then combined sequentially to prepare multi‐layer micro‐perforated nanofiber membrane (MPNM) for acoustic noise reduction. It was demonstrated that the multi‐layer MPNM exhibited a high absorption (constantly over 50%) in the frequency of 480–2500 Hz. In addition, the established theoretical model of the sound absorbing coefficient can accurately predict the sound absorption performance of the structure with different layers, which can provide a theoretical foundation for the design of the structure of the nanofibrous membrane acoustic absorber. Based on the proposed acoustic model, the relationships between the absorption properties and the parameters were investigated, and it was found that the effective acoustic absorption frequency range and acoustic absorption coefficient curve of the multi‐layer MPNM were closely related to the size and arrangement of hole diameter, perforation rate, fiber membrane thickness, and cavity depth. Optimization of the structural parameters utilizing algorithms can achieve superior sound absorption performance, with an average absorption coefficient of 0.81 in the frequency of 100–2500 Hz. This study provides a theoretical and experimental basis for the development of low‐frequency sound‐absorbing materials and is of great significance for optimizing the acoustic performance of nanofiber membranes and expanding their applications in various acoustic engineering applications.

Pinch-off of a regular bubble during the impact of droplets on a liquid pool

A droplet impacting a liquid pool can result in the pinch-off of a regular bubble. In this study, the cavity deformation and regular bubble pinch-off after droplets impacting a liquid pool were experimentally investigated. The results indicate that the phenomenon of regular bubble pinch-off results from the combined effects of cavity expansion and capillary wave propagation. The inertial force, viscous force, and droplet diameter are all crucial to the cavity evolution and the process of regular bubble pinch-off. The cavity depth increases with the droplet's inertial force but does not change with the droplet's viscous force. As the droplet's inertial force increases, the diameter of the regular bubble first increases and then decreases. The diameter of the regular bubble at We = 165 is almost four times that at We = 193. In addition, the peak size of the regular bubble decreases as the liquid viscosity increases, but increases as the droplet diameter increases. These variations in the regular bubble size are explained using a theoretical analysis. Finally, the effects of the inertial and viscous forces on the thresholds between no-bubble and regular-bubble pinch-off regimes are studied. As the Ohnesorge number increases from 1.37 × 10−2 to 2.03 × 10−2, the upper and lower critical Weber numbers for the occurrence of the regular bubble pinch-off can increase by 30 and 25, respectively. The theoretical boundaries of regular bubble pinch-off agree well with the boundaries observed in the experiments.

Intraocular amphiregulin and axial elongation in non-human adolescent primates

The purpose of the experimental interventional study was to examine the influence of intraocularly applied amphiregulin, a member of the epidermal growth factor (EGF) family, on axial length in young non-human primates. It included three non-human primates (Macaca mulatta), aged 4–6 years. The left eyes received three intravitreal injections of amphiregulin (400ng/50 μl) in intervals of 4 weeks, while the right eyes received three intravitreal injections of phosphate buffered solution (50 μl) at the same time points. Ocular biometry was performed in weekly intervals. At baseline, the left eyes (study eyes) were shorter than the right (control) eyes (20.69 ± 0.21 mm versus 20.79 ± 0.24 mm; P < 0.001), with an inter-eye axial length (AL) difference (left minus right eye) of −0.10 ± 0.23 mm. Inter-eye AL difference increased (P < 0.001) to 0.15 ± 0.18 mm at study end, at 12 weeks after baseline. Axial elongation during the study was higher (P < 0.001) in the left eyes (20.69 ± 0.21 mm to 21.05 ± 0.29 mm or 0.36 ± 0.30 mm) than in the right eyes (20.79 ± 0.24 mm to 20.90 ± 0.31 mm or 0.11 ± 0.17 mm). In a parallel manner, inter-eye difference in vitreous cavity depth combined with lens thickness (left eye minus right eye) increased from −0.04 ± 0.17 mm at baseline to −0.02 ± 0.21 mm (P = 0.02), 0.04 ± 0.10 mm (P = 0.002), and to 0.42 ± 0.67 mm (P < 0.001) at 5, 6, and 12 weeks after baseline, respectively. The results suggest that intravitreally applied amphiregulin as EGF family member led to an increase in axial length in adolescent non-human primates. It supports the hypothesis of amphiregulin as EGF family member being involved in the process of axial elongation.

A fast vibro-acoustic modeling method of plate-open cavity coupled systems

In this paper, a fast Chebyshev-Ritz method for vibro-acoustic analytical modeling of plate-open cavity coupled systems is developed for the first time. Based on the Chebyshev spectral method and the Rayleigh-Ritz solution procedure, the vibro-acoustic model of the open cavity coupled with a rectangular plate is established. The exterior acoustic field of the open cavity is expressed by the Rayleigh integral. Additionally, the Rayleigh integral is divided into a frequency-independent singular integral and a frequency-dependent non-singular integral, accelerating the calculation process. Furthermore, the Gauss-Chebyshev-Lobato sampling method is first developed for the plate-open cavity coupling model. By converting the integrals into tensor products, the method avoids complex quadruple integrals, increasing the efficiency of the entire integral operation. The vibration and acoustic responses from the proposed method agree well with existing literature and FEM analysis results, demonstrating the convergence and correctness of the current methodology. The mechanism of cavity depth on vibro-acoustic features of plate-open cavity systems is studied, which is less focused in the published literature. Other factors governing the plate-open cavity coupled model encompassed boundary conditions, fluid mediums, and plate thickness are fully examined. The results provide a theoretical foundation for the design and future research of plate-open cavity structures.

Coupling parameter analysis of photovoltaic double skin façade targeting photovoltaic etching ratio and cavity depth

The photovoltaic double skin façade (PV-DSF) represents the frontier of the advanced building envelope, whereas the prior parameter analysis had predominantly focused on the influence of individual factors. As two essential factors of PV-DSF, the photovoltaic etching ratio ϑ and cavity depth Dcav have garnered considerable academic attention, with little of them focusing on their coupling effect to energy performance. This paper investigates the impact of ϑ and Dcav using a spectrum-resolution numerical model, incorporating the concept of elementary effects derived from Morris method to quantify their interaction. The findings reveal that ϑ exhibits a non-monotonic impact, whereas the influence of Dcav is monotonic but non-linear. The optimal ϑ is found to be within the range of 30–50 %, while the lowest Dcav mostly outperforms other values, contrary to previous studies. This deviation is speculated to arise from the consideration of hot air generation energy. Furthermore, the variation of one factor can potentially alter the optimal value of the other. The second-order elementary effect between them demonstrates that their coupling effect is also non-linear and non-monotonic, with an impact as significant as that of Dcav alone. Overall, the correlations between ϑ and Dcav should be thoroughly considered during the design period.

Micro/Meso-Porous Double-Shell Hollow Carbon Spheres through Spatially Confined Pyrolysis for Supercapacitors and Zinc-Ion Capacitor.

Energy storage in supercapacitors and hybrid zinc ion capacitors (ZIC) using porous carbon materials offers a promising alternative method for clean energy solutions. The unique combination of hierarchical porous structure and nitrogen doping in these materials has demonstrated significant capacity for energy storage. Nevertheless, the full potential of these materials, particularly the relationship between pore structure configuration and performance, remains underexplored. Herein, a confined pyrolysis strategy based on the polymerization characteristics of polydopamine (PDA) was developed to construction of hollow carbon spheres with microporous/mesoporous dual shell structure. The depth of micropores and cavity can be controlled by adjusting the duration of heat treatment and hydrothermal treatment, in accordance with the decomposition and polymerization characteristics of PDA. Due to the elasticity of this structure, the relationship between the micro/mesoporous depth of the prepared carbon spheres and the energy storage performance in supercapacitors and ZIC is established. Through optimizing the ion transport capacity of carbon spheres and considering the influence of its internal cavity structure on energy storage, the resulting carbon spheres exhibit high specific capacitance of 389 F g-1 in supercapacitor and specific capacitance of 260 F g-1 and excellent stability with 99.3 % retention after 30000 chare/discharge cycles in ZIC.

Influence of cavity geometry on the bubble dynamics of nucleate pool boiling

Nucleate pool boiling is known for its exceptional heat transfer coefficients, with the use of cavities further improving bubble nucleation and heat transfer rate. To promote this heat transfer enhancement technique, a thorough understanding of the influence of cavity geometry on single bubble dynamics is required. The influence of depth and radius of cylindrical and conical cavities on the bubble dynamics of nucleate pool boiling of R1234yf were numerically investigated. The cavity radius was varied between 50 and 400 μm and the cavity depth between 100 and 1000 μm at a fixed heat flux of 28 kW/m2. It was found that the maximum equivalent diameter prior to departure was constant for cavities with radii smaller than 120 μm, while it increased linearly when increasing the cavity radius further. Cylindrical cavities exhibited high stability regardless of cavity radius or depth whereas conical cavities showed a decrease in vapor retention with increasing cavity angle. During the necking phase, the bubble interface became pinned at the cavity edge, depending on conical cavity angle, implying that smaller radii allowed for enhanced surface rewetting. Conical cavities could be considered as cylindrical cavities when the cavity angle was less than a quarter of the interface contact angle. When translating the single cavity findings to cavity array design, cylindrical cavities were recommended as they allowed for stable bubble behavior. For increased nucleation zones and rewetting, a sub-critical radius was recommended. Wider cavities were recommended for high superheat conditions as larger bubbles could enhance bubble growth.

Pan‐Antarctic Assessment of Ice Shelf Flexural Responses to Ocean Waves

AbstractUnderstanding the drivers of iceberg calving from Antarctic ice shelves is important for future sea level rise projections. Ocean waves promote calving by imposing stresses and strains on the shelves. Previous modeling studies of ice shelf responses to ocean waves have focused on highly idealized geometries with uniform ice thickness and a flat seabed. This study leverages on a recently developed mathematical model that incorporates spatially varying geometries, combined with measured ice shelf thickness and seabed profiles, to conduct a statistical assessment of how 15 Antarctic ice shelves respond to ocean waves over a broad range of relevant wave periods, from swell to infragravity waves to very long period waves. The results show the most extreme responses at a given wave period are generated by features in the ice shelves and/or seabed geometries, depending on the wave regime. Relationships are determined between the median ice shelf response and the median shelf front thickness or the median water cavity depth. The findings provide further evidence of the role of ocean waves in large‐scale calving events for certain ice shelves (particularly the Wilkins) and indicate a possible role of ocean waves in calving events for other shelves (Larsen C and Conger). Further, the relationships determined provide a method to assess the potential for increased calving as ice shelves evolve with climate change, and, hence, contribute to assessments of future sea level rise.

Clinical Efficacy of a Novel Titania Nanoparticle-Reinforced Bonding Agent in Reducing Post-Restorative Sensitivity: A randomized clinical trial.

To evaluate the clinical efficacy of novel titania-nanoparticle reinforced bonding agent on post-restorative sensitivity in patients. This triple-blinded, randomized clinical trial included participants (n = 60) having Class- I and II cavitations with a minimum cavity depth of 3mm at Department of Operative Dentistry & Endodontics, School of Dentistry, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad from January 5, 2023, to June 20, 2023. They were randomly assigned into two groups A and B (n = 30). After informed consent, restorative intervention was accomplished using an etch-and-rinse adhesive strategy. In Group-A, titania-nanoparticle-incorporated bonding agent was used for composite restoration, while in Group-B, bonding agent without nanoparticles was used. The primary outcome was assessed using Visual Analogue Scale mean score. Participants were instructed to rate their sensitivity status at follow-ups: 24 hours, one week, and one month. Mann-Whitney U test was employed to compare sensitivity between the two groups. According to results of this trial, a significant difference was observed between two groups after 24 hours (p = 0.004) and one week (p = 0.002). However, no discernible difference was observed after one month (p = 0.643). Post-restorative sensitivity in patients with composite restorations was reduced using titania-reinforced bonding agents as compared to bonding agents without nanoparticles. This shows that inclusion of titania nanoparticles into adhesive dentistry could be beneficial in resolving post-restorative sensitivity occurring with composite restorations.

Research on wavelet packet energy entropy extraction method for acoustic signal of tunnel lining cavity

Abstract Tunnel lining cavity is a common disease in high-speed railway tunnels, which seriously affects the safe operation of the line.At present, the commonly used method is manual knocking inspection, but it relies on manual judgment, subjective factors have great influence, and there are errors. This paper proposes a feature extraction method of acoustic vibration signal of tunnel lining cavity based on wavelet packet energy entropy and uses wavelet packet energy entropy to realize the identification of cavity defects.The full-scale simulation model of tunnel with a radius of 6m was constructed by COMSOL and different cavity conditions were set up. The wavelet packet energy entropy characteristics of acoustic signals were extracted and analyzed. The mapping relationship between cavity depth and cavity size and wavelet packet energy entropy was explored. The wavelet packet energy entropy and frequency band distribution characteristics were extracted to realize the identification of cavity defects.The local model which can characterize the whole tunnel is designed and the embedded defects are verified by experiments. The results show that the wavelet packet energy entropy can be used as the identification feature of tunnel lining cavity defects. When the wavelet packet energy entropy is less than 2.53, the existence of tunnel lining cavity defects is characterized.When the wavelet packet energy entropy is in the range of 2.53-2.94, it characterizes the existence of the transition boundary between tunnel lining cavity defect and no disease.This index can be used to realize the rapid and effective identification of cavity defects.&amp;#xD;