Cavity Depth Research Articles

Experimental and numerical investigations of cavity flame spread in double skin façade

In recent decades, double-skin façades (DSFs) have gained popularity in modern commercial buildings. However, their cavities can potentially accelerate flame spread, raising significant concerns regarding façade fire safety. Given that existing studies focus on the DSF component failures and fire stop measures without modeling validation, this study presents real-scale DSF fire experiments and modeling in accordance with JIS A 1310, conducted without combustibles to clarify fire behaviors within the cavity. The experiments employ HRRs of 600-900 kW and cavity depths of 0.4 and 0.8 m, highlighting that flame attachment to the facing wall is dependent on HRRs rather than cavity depths. Subsequently, Computational Fluid Dynamics (CFD) is utilized to investigate DSF fires, with validation against experimental temperature distribution and flame morphology. Furthermore, the validated CFD modeling is applied to scenarios with extended cavity depths and varied opening shapes, indicating that a cavity depth of ≥0.7 m mitigates flame spread for an opening ratio of n≥1. The Modified-McCaffrey-Yokoi (MMY) model is proposed to characterize façade flame temperatures across varied cavity depths, and its convergence, featured by opening shapes and HRRs, is categorized to distinguish cavity flame behavior.

Influence of cavity and ramp layout on combustion performance in a strut-based scramjet combustor

The computational analysis focuses on the flow performance of a wall-mounted cavity and ramp within DLR scramjet model operating in a reacting flow environment. The analysis encompasses a base setup aligned with DLR experiments, along with suggested configurations featuring different lower wall cavity depth and a fixed upper wall ramp. The 2-D Reynolds-Averaged Navier-Stokes approach (RANS) combined with Shear Stress Transport (SST) k-ω turbulence model, which incorporates single-step reaction chemistry, is utilized in steady-flow simulations. Subsequently, the unsteady-flow computations are completed using the Delayed Detached Eddy Simulation (DDES) with the SST k-ω turbulence model as a continuation of RANS analysis to compute and observe the coherent structures by using data driven methods. To examine shock structures and their associations with shear layer mixing characteristics, the cavity and ramp are positioned downstream of the strut. Inclusion of the cavity and ramp increase the number of shock waves in the flow substantially. Accordingly, complete combustion occur earlier than in the baseline model which is accompanied by a subtle increase in total pressure loss. Due to intense interactions between shock waves and shear layers, combustion zone widens laterally as the cavity displaces the shock train downstream of the strut injector. DDES results are processed to observe the dynamics and the coherent structures employing Dynamic Mode Decomposition (DMD) and Spectral Proper Orthogonal Decomposition (SPOD) methods. Both analysis show that the recirculation zone proceeds into the core engine with the progressive deepening of the cavity leading to a consequential stationary combustion.

Optimum Geometry of Double-skin Self-Shading Facade of Classrooms with the Aim of Creating Energy Saving and Visual Comfort in Isfahan Province, Iran

The significant energy consumption in educational spaces worldwide and its environmental impact greatly influence the quality of space, learning levels, and student comfort. Despite offering free school energy costs, developing countries like Iran have not established specific design principles to ensure student comfort. Additionally, the poor design of school building exteriors, such as the common installation of large, unshaded windows in Iranian schools, causes glare issues. The primary objective of this study is to control direct sunlight and increase shading, thereby reducing its impact on energy consumption and enhancing visual comfort. This paper proposes a novel solution that combines a self-shading facade with a double-skin facade for classroom spaces. The study variables, involving the modification of the geometry of the double-skin self-shading facade via DesignBuilder software and the Daysim plugin, were compared to a simple double-layer facade. Based on the results, the optimal scenario for the self-shading double-skin façade with the specifications of a triangular pyramid module shape, ridge position fold 3/2 the module height, cavity depth 7.0, and number of module 2×2 exhibited 40% lower cooling load, 25% lower heating load, and 95% lower lighting load than a simple double-skin facade. At the same time, all scenarios of the new solution provided better visual comfort and daylighting criteria compared to the simple double-skin facade. The modularity and use of indigenous brick materials in the double-skin self-shading facade design reduce construction costs.

Pulpitis tendency in teeth with vital pulp restored with composite resins: a cross-sectional retrospective study

Background: This study evaluates pulpitis tendency in vital teeth restored with composite resin after at least one year, focusing on the effect of cavity depth and the use of a base material on pulp status. Methods: A retrospective analysis was conducted on 212 patients with one tooth restored by dental senior students. At the follow-up, periapical and bitewing radiographs, cold tests, percussion, and palpation were performed. Cavity depth was measured from bitewing radiographs, and the periapical index (PAI) was recorded. The restored teeth were compared with contralateral sound teeth to assess the impact of the resin on pulp tissue. Results: Composite resin restorations significantly affected pulp status compared to intact teeth (p=0.002). Five out of 212 teeth became necrotic, and four developed symptomatic irreversible pulpitis (SIP). Four necrotic cases occurred in cavities deeper than 3.60 mm, and all SIP cases were associated with cavities deeper than 3.10 mm. Cavity depth was a significant predictor of adverse pulpal outcomes. However, using calcium hydroxide as a base did not significantly affect pulp health. Conclusions: The study concludes that composite resin restorations, mainly in deep cavities, can negatively impact pulp vitality. Cavity depth is a key factor in the risk of pulp necrosis and SIP, while calcium hydroxide base did not reduce pulpitis incidence. Larger studies with longer follow-up periods are recommended to confirm these findings and explore potential protective factors.

Penile inversion vulvo-vaginoplasty with scrotal graft for trans women: surgical technique and results of initial experience.

A significant proportion of trans women is demanding for a genital gender-affirming surgery, with vulvo-vaginoplasty being the most frequently requested procedure. The gold standard for primary vaginoplasty in trans women is the penile skin inversion technique with scrotal skin graft, which allows for increased depth of the vaginal cavity. The assessment of vulvo-vaginoplasty outcomes utilizing penile skin inversion and scrotal skin graft in individuals assigned male at birth in the surgeon's learning curve involves evaluating aesthetics, functionality, and sexual aspects. A total of 76 individuals assigned male at birth were included in 2 French university hospitals from 2020 to 2022. They underwent vulvo-vaginoplasty following 8 key steps: scrotal skin excision; bilateral orchiectomy; dissection between the rectum, bladder, and prostate; penile dissection; clitoroplasty; urethroplasty; penile skin inversion with scrotal skin graft; labioplasty. The average follow-up period was 12.4months, with participants averaging 35.7years of age. Each patient was invited to complete a questionnaire during follow-up. The study's outcomes encompassed the assessment of both early and late surgical complications, postoperative sexuality, aesthetic results, and voiding satisfaction. Of the total patients, 15.8% experienced major early postoperative complications, while 3% encountered major late postoperative complications. No complication was classified 4 or 5 in Clavien-Dindo scale. Most early complications were related to issues in vulvar healing, which did not compromise long-term aesthetic results. Patients-reported satisfaction was 82% after the procedure. Vulvo-vaginoplasty utilizing penile skin inversion and scrotal skin graft for individuals assigned male at birth is a reproductive surgery procedure that can be successfully performed by experienced urologist. It achieves high patient-reported satisfaction even during the learning curve. The surgical procedures were consistent, and the sizable cohort of patients accurately reflects the learning curve of both surgeons. However, extrapolating long-term complications is challenging due to the relatively brief follow-up period. Additionally, there is a lack of self-reported sexual function data, and the scales used to assess patient-reported quality of life and urinary satisfaction are not specifically validated for transgender patients. Vulvo-vaginoplasty utilizing penile skin inversion and scrotal skin graft for individuals assigned male at birth is a complex surgical procedure. It appears to be achievable by experienced urologists during their learning curve, resulting in similar functional and surgical outcomes, along with high patient satisfaction.

Investigation on torsional forces and angles at the nut and pedicel junction (NPJ) revealed varying cashew apple (hypocarp) and nut separation efficiency at different developmental stages in cashew

Cashew is a highly valued tree nut crop that is widely grown for nourishment and industrial applications. The study of fruit and nut separation forces is a necessary for efficiently detaching the nuts from the swollen pedicel or hypocarp referred to as cashew apple (pseudo fruit). In this study, the torsional/twisting forces (TF) required for separating the nuts from the cashew apples (CA) were analyzed at the nut pedicel junction (NPJ) in different cultivars at different fruit developmental stages [BBCH (BiologischeBundesanstalt, Bundessortenamt und ChemischeIndustrie) stage code: 711, 713, 715, 717, 719, 811, 813, 815, 817, 819] and days after fall to devise strategies for efficient separation of nuts and CAs. The TF and torsional/twisting angle (TA) were measured using a novel strain gauge-based reaction type torque transducer and a customized fixture. The CA firmness (CAF), and CA cavity depth, length, and width at the NPJ were also measured. Significant variations were observed in the TF and the TA at different fruit developmental stages and days after fall (DAF) in the studied cultivars. The TFs increased from 711 to 813 stages and subsequently declined from 813 to 819 stages and with increasing DAF. Further, the TA increased significantly with the development of fruits from 711 to 819 stages and days after fall. The analysis of the relationship between TF and the physical properties of CA showed that CA firmness and CA cavity depth at the NPJ had significant positive correlations. Further, the analysis of the relationship between the TA and the CA properties showed that CA firmness has significantly negative correlations. The findings of this study are valuable for the development of new cashew cultivars with low TF and TA suitable for mechanical separation and the designing of machinery with versatile end-effectors and twisting mechanisms for efficient separation of nuts from CAs.

Effect of cavity depth on air-breathing rotating detonation engine fueled by liquid kerosene

In our recent experimental investigation, the feasibility of a liquid-kerosene-fueled air-breathing/ramjet rotating detonation engine featuring a cavity-based annular combustor has been experimentally demonstrated. Achieving stable operation and organized detonation combustion within the rotating detonation combustor presents significant challenges that demand further investigation. Thus, this study aimed to deepen our understanding of the optimal geometrical configuration of a cavity-based annular combustor operating in air-breathing mode. Numerous experiments were conducted to evaluate the impact of varying cavity depths on combustion performance under a supersonic incoming flow with a total temperature of 860 K. The findings indicate that adequate cavity depth is essential for the generation of kerosene-fueled rotating detonation waves in air-breathing mode. Notably, a kerosene–air rotating detonation wave was achieved in combustors with cavity depths ranging from 10 to 30 mm while maintaining a supersonic heated air mass flow rate of approximately 1000 g/s and a minimum equivalence ratio of 0.77. However, at a cavity depth of 10 mm, both the propagation velocity and peak pressure of the rotating detonation waves were significantly lower compared to those at 20 and 30 mm, thereby suggesting that the depth of 10 mm may require optimization. Additionally, optical observations revealed that the detonation reaction zone was located further from the combustor head as cavity depth increased. This indicates that deeper cavity depths allow for longer mixing and preheating times of the combustible mixture before detonation, thereby enhancing detonation performance. This study clarifies how cavity depth influences liquid-fueled rotating detonation and provides guidelines for designing cavity-based annular combustors in air-breathing rotating detonation engines.

Investigation on flow–acoustic resonance behaviors inside ducts with tandem cavities using a high-order spectral/hp element method

This study numerically investigates the flow–acoustic resonance behaviors inside ducts with tandem cavities, containing the flow-excited acoustic eigenmodes and elevated flow dynamics under self-sustained acoustic forcing. An advanced high-order spectral/hp element method integrated with implicit large-eddy simulations was utilized to solve the nonlinear compressible Navier–Stokes equations, which effectively identified the fully coupled self-sustained flow–acoustic resonance fields. The benchmark shallow cavity configuration with a length-to-depth (L/D) ratios of 2 was motivated by the experimental findings from Shaaban and Ziada [“Fully developed building unit cavity source for long multiple shallow cavity configurations,” Phys. Fluids 30, 086105 (2018)], in which the intensive flow–acoustic resonance was occurred at a Reynolds number of 1.3×105, and we further investigated three deeper cavity configurations with L/D of 1, 2/3, and 1/2 for numerical validation and further comparison. Subsequently, aeroacoustic characteristics were assessed by analyzing the wall pressure fluctuations, indicating broader resonance regions and augmented pressure pulsation amplitudes extending from main duct to local cavity volumes with larger cavity depths. As feedback, the intensified acoustic forcing can modulate the cavity flow dynamics into stronger fluctuation levels. Furthermore, the spectral proper orthogonal decomposition analysis was conducted on the pressure fields and velocity fields, respectively. The significant fluctuations in acoustic pressure were linked to transitional acoustic modes that were present as global modes in the main duct and local modes in tandem cavities. As for velocity analysis, coherent vortex structures were extracted along the cavity entrances. These vortex structures caused progressively amplified velocity fluctuations and classified the shear layers into two dynamic motions, i.e., a flapping motion in shallow cavities and a rolling-up motion in deep cavities.

Teleportation of Qubits in a Kicked Nonlinear Cavity with Ultra-short Pulses via Quantum Noisy Channels

AbstractIn this paper, we delve into the profound ramifications of noise on qubit teleportation between the esteemed figures of Alice and Bob, ruthlessly quantifying the negativity and distance of the transmitted information. Through the invocation of an audacious modification to the Hamiltonian of the Jaynes–Cummings model, incorporating the ferocious power of a kicked cavity and ultra-short laser pulses, we unleash a tempest that unrelentingly shapes the entanglement and quality of the teleported information. Moreover, we fearlessly venture into the treacherous territory of noisy channels, including the formidable adversaries of phase flip and double phase flip channels, as they mercilessly assail the teleported state, engendered by the tumultuous interaction within the unforgiving depths of the kicked cavity, only to be met with our resolute projection.

Design and Testing of a Branched Air-Chamber Type Pneumatic Seed Metering Device for Rice

To meet the diverse seeding requirements of super hybrid rice, common hybrid rice, and conventional rice—which vary from 1 to 3 seeds, 2 to 4 seeds, and 5 to 8 seeds per hole, respectively—this study developed a branched air-chamber type pneumatic seed metering device for rice. The device utilizes an air chamber control board to manage the branched air chamber casing, enabling precise adjustments to the seeding quantity. This study presents a theoretical analysis of the seed metering device’s operation and its critical components. Structural parameter optimization was conducted using Ansys-Fluent (2021 R1) software, followed by multi-objective optimization of operational parameters through bench testing. Simulation results indicated that optimal vacuum pressure in the seed metering disc pores reached a maximum of 857 Pa with a chamber depth of 22 mm, an angle of 100°, and a cavity depth of 25 mm, achieving a minimal coefficient of variation of 0.86%. Bench test results showed that for seeding targets of 1 to 3 rice seeds per hole, the optimal operational parameters were: two openings, a working vacuum of 1355 Pa, and a rotor speed of 32.78 r/min, resulting in a missed seeding rate of 4.70%, a qualification rate of 85.81%, and a re-seeding rate of 9.49%. For targets of 2 to 4 seeds per hole, the best parameters included three openings, a working vacuum of 1357 Pa, and a speed of 32.87 r/min, with a missed seeding rate of 4.60%, a qualification rate of 85.59%, and a re-seeding rate of 9.81%. For 5 to 8 seeds per hole, optimal parameters were six openings, a vacuum of 1339 Pa, and a rotor speed of 31.07 r/min, yielding a missed seeding rate of 4.09%, a qualification rate of 87.27%, and a re-seeding rate of 8.64%. These findings demonstrate that the branched air-chamber type pneumatic seed metering device effectively meets the varied direct seeding requirements of rice, enhancing the adaptability of pneumatic seed metering devices to different seeding quantities in rice and potentially informing the design of pneumatic seeders for other crops.

Cross-scale electrochemical machining of superhydrophobic end face cavities via microstructured surface cathodes

In order to solve the problems of low precision of the electrochemical machining cavity and poor end face quality, this paper proposed a microstructured surface cathode and established the electrical and flow field models of the machining process. Theoretical analysis and simulation results show that the microstructure surface is helpful to improve the current density of the machining gap, and due to the superhydrophilic characteristics of the surface, hydrogen bubbles are promoted to separate from the cathode surface, the volume fraction of hydrogen bubbles in the end gap is reduced, and the mass transfer efficiency of the electrolyte is improved. A nanosecond laser machining system is used to prepare the array microstructure on the cathode surface. Compared with the experimental results of the original cathode, the feed rate of the proposed cathode increased from 0.10 mm/min to 0.20 mm/min and the machining process is more stable. The standard deviation of the width along the cavity depth direction is reduced from 285 μm to 175 μm, improving the machining accuracy of cavity. In addition, the microstructure on the cathode surface is replicated on the cavity end face and the reasons for the differences in size and shape between the micro-pit structure on the cavity end face and the microstructure on the cathode surface are analysed. The static contact angle of the cavity face is measured to be 150.5°, demonstrating excellent superhydrophobic properties. This method realizes cross-scale electrochemical machining of millimetre-scale cavities and micron-scale pits.

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.

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.