Bar Model Research Articles

The Rotation of Classical Bulges in Barred Galaxies in the Presence of Gas

Barred galaxies often develop a box/peanut pseudobulge, but they can also host a nearly spherical classical bulge, which is known to gain rotation due to the bar. We aim to explore how the presence of gas impacts the rotation of classical bulges. We carried out a comprehensive set of hydrodynamical N-body simulations with different combinations of bulge masses and gas fractions. In these models, both massive bulges and high gas content tend to inhibit the formation of strong bars. For low-mass bulges, the resulting bar is stronger in cases of low gas content. In the stronger bar models, bulges acquire more angular momentum and thus display considerable rotational velocity. Such bulges also develop anisotropic velocity dispersions and become triaxial in shape. We found that the rotation of the bulge becomes less pronounced as the gas fraction is increased from 0 to 30%. These results indicate that the gas content has a significant effect on the dynamics of the classical bulge, because it influences bar strength. Particularly in the case of the low-mass bulges (10% bulge mass fraction), all of the measured rotational and structural properties of the classical bulge depend strongly and systematically on the gas content of the galaxy.

Multiscale analysis of the flexural performance of FRP reinforced concrete structures

Based on existing experimental data and analysis, seven different fiber-reinforced polymer (FRP) bar models including carbon fiber-reinforced polymer (CFRP), basalt fiber-reinforced polymer (BFRP), aramid fiber-reinforced polymer (AFRP), glass fiber-reinforced polymer (GFRP), GFRP and CFRP combined (G–C), GFRP and AFRP combined (G–A), BFRP and CFRP combined (B–C), and BFRP and AFRP combined (B–A) were established. Finite element simulation analysis was conducted on seven different FRP bar combinations under static load bending tests. The flexural behavior of the specimens reinforced with different FRP bar combinations and their influencing factors were analyzed. The results showed that using AFRP as the reinforcement material for FRP composite bars in FRP reinforced concrete beams cannot effectively enhance the overall load-carrying capacity of the composite bars. The combination of CFRP with GFRP and BFRP bars significantly increases the stiffness of the FRP bar structure and improves the structural load-carrying capacity of the concrete beams.

The Development and Effectiveness of the HOTS Mathematical Problem-Solving Framework with the Bar Model Strategy on Student Achievement

This study aims to develop and assess the effectiveness of the HOTS Mathematical Problem Solving Framework (HMPSF) with the Bar Model Strategy on the achievement of Year Five Students. This study is a design and development study involving three phases. The first phase is a needs analysis study administered to 65 National School Mathematics teachers and 102 Year 5 students. The second phase is the design and development phase using the Fuzzy Delphi method involving 15 experts in Mathematics Education. Phase three is the implementation and testing phase of HMPSF with the Bar Model Strategy. In this phase, the study was conducted through a quasi-experimental design of a non-equivalent group of pre-post analysis involving 63 Year Five students from two schools in Kinta Utara district, Perak, Malaysia. The sampling process is done randomly. Data were analyzed through ANOVA and MANOVA. The needs analysis conducted show that 92.2% of teachers and 98.04% of students stated that there is a need to develop the HMPSF. Fuzzy Delphi analysis showed that the three main conditions were met (i) Threshold value, D ≤ 0.2, (ii) Percentage of expert agreements,> 75% and (iii) α-cut value (Fuzzy score), ≥ 0.5. This finding shows that the HMPSF with the Bar Model Strategy has been successfully developed through the agreement of 15 experts. The findings in phase three indicate that there is a significant difference in the mean of the post-group test for student achievement. The findings of the Multivariate Pillai’s Trace test also show that there is a significant effect between the pre and post-test. In conclusion, the HMPSF with the Bar Model Strategy developed is proven can enhance student achievement. Conclusively, the HMPSF with the Bar Model Strategy is suitable as a main guide for teachers and students in strengthening problem-solving skills in the field of Numbers and Mathematical Operations.

Physicochemical-mechanical simulation of the short- and long-term performance of FRP reinforced concrete beams under marine environments

To broaden the applications of fiber reinforced polymer (FRP) reinforced concrete structures under marine environments, it is crucial to gain a fundamental understanding of their short- and long-term performance. In this study, the effectiveness of the proposed multi-scale simulation platform, which incorporates the proposed degradation model of FRP bars, is quantitatively assessed via the comparison between the predicted results and experimental load-displacement curves under different marine conditions (continuous immersion, wet-dry cycling and subtropical marine atmosphere). The spatially physical, chemical and mechanical information, such as pH value, moisture, hydration degree, strength, porosity during the exposure was also revealed. Finally, the long-term structural performance of FRP-reinforced concrete beams exposed to the predefined environmental conditions over durations of 20, 50 and 100 years are assessed using the multi-scale simulation platform. After 50 years of exposure, the load-bearing capacity of GFRP-reinforced concrete beams was found to decrease by 35.8 % in immersion conditions and by 17.9 % in subtropical marine atmosphere. The degradation of the load-bearing capacity in the case of 100 years exposure to subtropical marine atmosphere was found to be less severe than that (23.1 %) in the case of 50-year immersion. These findings not only deepen our understanding of the material and structural properties of FRP-reinforced concrete beams under various environmental conditions, but also validate the effectiveness of the proposed multi-scale platform.

The digital twin use for modeling the multi‐storey building response to seismic impacts

AbstractThis work is dedicated to theoretical and experimental research on constructing a digital twin for a 24‐story building located in a seismic zone with the possibility of seismic vibrations of up to eight on the Richter scale. A digital model of the building was developed considering the changes in its geometry (damage or absence of structural elements). This requires detailed field inspections of partially constructed buildings and consideration of the inspection results when constructing a digital model. The boundary conditions, in addition to the geometric characteristics of the building, include the physical and mechanical characteristics of all its structural elements obtained through nondestructive testing methods. Discrepancies between the structural elements' design and actual concrete classes were identified. The initial conditions included real accelerograms at the location of the building, which served as input data for the direct dynamic analysis. Thus, there is a need to develop a hybrid system for modeling the stress–strain state of a 24‐story building that uses information technologies (Internet of Things) with sensors during research. Such an IoT system, combined with one information network using cloud technologies, allows us to obtain the necessary information in real‐time, highlighting the features of the building (the second stage of constructing the digital twin). The bar and spatial models of buildings with distributed parameters of structural stiffness at bending and shear and the mass and mass moment of inertia were considered. The results of numerical studies of the first form of natural vibrations for the building rod (according to the expressions obtained by the authors) and spatial models (performed using the LIRA‐CAD software package developed in Ukraine based on the finite element method) are presented. A comparison with the first experimental form of natural vibrations confirmed that considering the moment of inertia of the building mass makes it possible to determine the ordinates of the self‐form of vibrations and seismic horizontal loads more accurately. The experimental first frequency and form of natural vibrations of a 24‐story residential building in Odesa were obtained from the results of vibration monitoring at the construction stage (16 floors were erected) and after all 24‐floor erection. The direct dynamic method of building calculations for seismic effects specified by earthquake accelerograms was used along with the method proposed by the authors to consider damping during forced building vibration calculations and the actual physical and mechanical characteristics of concrete and reinforcement obtained by non‐destructive testing methods. The calculated vibration amplitudes at the top of the building cantilever model were compared with the damping parameters obtained using the Voicht model and the authors' method under the influence of an accelerogram recorded during the powerful 1977 Bucharest earthquake with an epicenter in the Vrancea area (Romanian Carpathians).

The Milky Way bar pattern speed using Hercules and Gaia DR3

ABSTRACT The distribution of moving groups in the solar neighbourhood has been used to constrain dynamical properties of the Milky Way for decades. The kinematic bimodality between the main mode (Hyades, Pleiades, Coma Berenices, and Sirius) and Hercules can be explained by two different bar models – via the outer Lindblad resonance of a bar with a high pattern speed (∼55 km s−1 kpc−1), or via the corotation resonance of a bar with a low pattern speed (∼40 km s−1 kpc−1). Recent works directly studying the kinematics of bar stars and gas flows near the centre of the Galaxy have converged on the low pattern speed model. In this paper, we independently confirm this result by using Gaia DR3 to directly study the variation of Hercules across Galactic azimuth. We find that Hercules increases in Vϕ and becomes stronger as we move towards the minor axis of the bar, and decreases in Vϕ and becomes weaker as we move towards the major axis of the bar. This is in direct agreement with theoretical predictions of a low pattern speed bar model in which Hercules is formed by the corotation resonance with stars orbiting the bar’s L4/L5 Lagrange points.

Operating Properties of Deep Hole Boring Tools with Modified Design.

This paper presents the results of research work on the revised design of a deep hole boring tool. The study was divided into three stages: theoretical, experimental and operational. In the theoretical part, a 3D model of the actual boring bar was created, which was subjected to strength tests using the Finite Element Method (FEM), and then prototypes of new deep hole boring tools were made with structural modifications to the shank part of the tool. For the polymer concrete core of a shank, there was a 14.59% lower displacement, and for the rubber-doped polymer concrete (SBR-styrene butadiene rubber) core of a shank there was a 4.84% lower displacement in comparison to the original boring bar. In the experimental part of the study, the original boring bar and the prototypes were subjected to experimental modal analysis and static analysis tests to compare dynamic and static properties. In the operational part of the study, boring tests were carried out for various workpiece materials, during which the basic parameters of the surface geometric structure (SGS), such as roughness Ra and Rz, were studied. Despite the promising preliminary results of the theoretical and experimental studies, using the described modifications to the boring bar is not recommended.

Statics and stability of diagonalless beams of particular kind – preliminary studies

Attractive large-scale glazing is currently an architectural trend. However, achieving adequate stiffness for larger glazing spans requires the use of complex cross-sections, generally aluminium sections of considerable height. Members with openwork webs are sometimes used in order to achieve increased load-bearing capacity and stiffness with reduced weight. The disadvantage is that this solution takes up a lot of space inside the building. A recently patented diagonalless member attempts to solve the above-mentioned problems. The member is fully demountable and allows glass units to be installed in the space between the chords. It consists of two chords spaced apart by metal sleeves with bolts passed through them. In this study, preliminary qualitative experimental tests were carried out to determine the behaviour of the member under load and to identify zones sensitive to local deformation. On this basis, numerical models (bar and 3D solid models, including contact interactions) were created and tested. Subsequently, the optimum sleeve spacing was determined, the effect of rotational and translational stiffness reduction at the nodes was investigated, and stress concentration zones and forms of stability loss were identified. A new form of local loss of stability of the chord facewall was identified, the so-called sliding push effect of the chord walls on the sleeve (within the larger openings). This is a completely different type of chord facewall failure from that found in known tubular welded joints. The research programme focused on identifying the phenomena occurring in the new member in order to provide a basis for further, more advanced analyses.

Radial and azimuthal gradients of the moving groups in Gaia DR3: The slow and fast bar degeneracy problem

The structure and dynamics of the central bar of the Milky Way (MW) are still under debate whilst being fundamental ingredients for the evolution of our Galaxy. The recent Gaia DR3 offers an unprecedented detailed view of the 6D phase space of the MW, allowing for a better understanding of the complex imprints of the bar on the phase space. We aim to identify and characterise the dynamical moving groups across the MW disc, and use their large-scale distribution to help constrain the properties of the Galactic bar. We used 1D wavelet transforms of the azimuthal velocity ($V_ distribution in bins of radial velocity to robustly detect the kinematic substructure in the Gaia DR3 catalogue. We then connected these structures across the disc to measure the azimuthal (phi ) and radial ($R$) gradients of $V_ of the moving groups. We simulated thousands of perturbed distribution functions using backward integration, sweeping a large portion of parameter space of feasible Galaxy models that include a bar, in order to compare them with the data and to explore and quantify the degeneracies. The radial gradient of the Hercules moving group ($ V_ R$ = 28.1pm 2.8 $) cannot be reproduced by our simple models of the Galaxy that show much larger slopes both for a fast and a slow bar. This suggests the need for more complex dynamics (e.g. a different bar potential, spiral arms, a slowing bar, a complex circular velocity curve, external perturbations, etc.). We measured an azimuthal gradient for Hercules of $ V_ = -0.63pm $deg$^ $ and find that it is compatible with both the slow and fast bar models. Our analysis points out that in using this type of analysis, at least two moving groups are needed to start breaking the degeneracies. We conclude that it is not sufficient for a model to replicate the local velocity distribution; it must also capture its larger-scale variations. The accurate quantification of the gradients, especially in the azimuthal direction, will be key for the understanding of the dynamics governing the disc.

Bond-slip model of headed bar and its application to component-based model for precast concrete joints under accidental loads

This study focused on investigating bond-slip behaviour of headed bars embedded in well-confined concrete. Test results based on eight pull-out specimens under displacement-controlled incremental loading showed that recommended development lengths from ACI318–19 are conservative in developing ultimate strength of headed bars associated with smaller slips than straight bars. Moreover, it was found that different (but sufficiently long) embedment lengths had a significant effect on the free-end slip but negligible effect on the loaded-end slip of headed bars. Additionally, the study highlighted the significance of head bearing in anchorage formation, especially during inelastic stage when bond strength had deteriorated. To address inaccuracy in predicting structural behaviour caused by inadequate anchorage strength of headed bars, a macro bond-slip model was proposed based on correlation in strain distribution obtained from the pull-out tests. Subsequently, the proposed model was incorporated into a component-based model (CBM) and validated against test results of PC joints under seismic loading. A numerical investigation using the validated CBM was conducted to study behaviour of exterior PC joints with headed bars and special detailing. These included Type X joint with X-bent bars and plastic hinge relocation (PHR), and Type A joint with an additional bar layer (ABL) in the beam-joint region, subjected to extreme loads such as seismic action or progressive collapse. The results revealed that seismic behaviour of exterior joints was governed by ductile failure of the beam at the PHR and vertical joint interface in Type X and Type A joints, respectively. Progressive collapse was primarily caused by column failure, with flexural and catenary action effectively preventing collapse. Notably, under both loading conditions, presence of ABL in Type A joint and X-bent bars with PHR in Type X joint improves flexural strength of beams at critical sections and joint shear strength, ultimately enhancing structural performance of joints. Design recommendations include replacing hooked bars with headed bars as well as implementing X-bent bars with PHR and ABL in PC joints. The authors advocate the strong-column-weak-beam design approach as an effective measure to prevent progressive collapse.

MODUL KEMAHIRAN BERFIKIR ALGEBRA UNTUK PELAJAR TINGKATAN SATU

Algebraic Thinking Skills (KBA) is one aspect of skills that students need to master in order to solve non-routine problems. These skills are also needed as a basis for preparing students to enter university studies and job fields that require logical and analytical thinking. However, the performance of Malaysian students in solving algebraic problems has not yet reached a satisfactory level according to the TIMSS 2019 and PISA 2018 reports. Thus, the Algebraic Thinking Skills Module (MBA) was developed to foster KBA through three constructs namely i) arithmetic generalization, ii) functions, and iii) modeling. MBA is developed based on heuristic methods through Polya absorption Model and digital bar. A bar model is a rectangular illustration constructed to represent known and unknown quantities and relationships between quantities. The digital bar model refers to the free application of the bar model at the link https://mathsbot.com/manipulatives/bar. The KBA test was constructed and administered as a pre- and post-test to 120 Form One students from a rural school in Sabah. The results of the paired sample t-test showed that there was a significant difference in the mean score between the pre-test and the post-test (t(119) = -17.553, p < .05) after the intervention using MBA. This shows that MBA can improve KBA through heuristic methods. This innovation is expected to be developed in rural schools to form students who think algebraically and are literate in digital technology.

Nonlinear Forced Vibration Analysis using ‘Elmer’ FEM Package to Develop Poincaré Map and Correlation Method-based Damage Indicators

With the rapid advancement of sensor technology, structural health monitoring (SHM) is also blossoming with prowess in the field of civil, mechanical and aerospace engineering. It deals with the initiation of damage and its characteristic behavior in a deterministic or predictive way. The time-dependent fluctuation associated with the dynamic motion of structures was addressed with few efficient indicators in the past to identify the presence of damage as well as to localize the faulty area. The formulation of all those indicators is validated on specific structural arrangements with certain assumptions. This limitation is considered in this article to project the global applicability of the method along with the inherent constraints. The damage detection in the time-domain is considered to utilize direct accessibility of responses from the sensors attached to the members. It reduces the computational difficulty in transforming response to another domain and also associated approximations that emerge through numerical calculations. Broadly, two types of methods are discussed in this article along with modelling and analysis procedure; methods developed from cross-correlation of response and graphical method or Poincaré map. The model of cantilever beam and axial bar is developed in FreeCad where damage is induced by reducing either thickness or Young’s modulus of damaged elements to simulate cracked member. Meshing of member is done in Gmsh. To generate response history of state variables a newly developed finite element (FE) analysis software package Elmer is then employed for the dynamic analysis of the member with geometric nonlinearity. At last, application of Teager energy operator (TEO) in noise reduction is explained with a general example.

High Strain Rate Modeling of CFRP Composite Under Compressive Loading

An in-depth understanding of how carbon fiber-reinforced plastics (CFRP) respond to intense strain rates is essential, particularly in non-linear deformation and dynamic loading situations. The researchers undertook a computational study to examine the behavior of CFRP composites when exposed to high strain rates under compressive loading. Specifically, they employed Split Hopkinson Pressure Bar models for cohesive interfacial simulations, continuum shell analysis, and laminated composites oriented at 0° at a strain rate equivalent to 900 s-1. The Finite Element model utilized a custom Hashin damage model and a vectorized user material (VUMAT) sub-routine to identify degradation damage within the CFRP composite model. The quasi-isotropic composite demonstrated a significant enhancement in dynamic strength compared to static values, attributed to its intense sensitivity to strain. As confirmed by experimental test results, numerical simulations accurately predicted stress (σ)-strain (ε) and strain rate (ἐ) curves. Additionally, it was observed that the relationship between damage behavior varied depending on the element type used.

Experimental Study on the Effects of Straight and Ring-Type Steel Fibres on the Bond Behaviour of Steel Bars in Rubber-Recycled Aggregate Concrete

The application range of rubber-recycled aggregate concrete (RRAC), a new type of green building material, is currently limited due to performance defects, including low hardness, high water absorption, and poor adhesion. To expand its application in reinforced concrete structures, it is crucial to enhance the bonding performance between RRAC and steel bars. In this study, the effects of adding straight steel fibres (SSFs) and ring-type steel fibres (RSFs) to RRAC were investigated, in order to enhance the bonding performance. To investigate the impact of steel fibres (SFs) on the bonding properties of RRAC and steel bars, a total of 51 specimens were subjected to pull-out tests to systematically examine the impact of SSF and RSF dosages on the bonding performance. The results demonstrated that incorporating the optimal amount of SSFs and RSFs can significantly improve the bond strength and bond stiffness. Moreover, the combined use of SSFs and RSFs yielded even better enhancement effects. The RRAC exhibited remarkable performance, when the total content of SFs was 1.2% and the proportion of RSFs 75%. In this case, the bond strength and bond stiffness were enhanced by 3.7% and 53.88%, respectively. Finally, a bond–slip constitutive model for RRAC and steel bar was established. The combined use of SSFs and RSFs minimizes the limitations of poor mechanical properties in traditional RRAC and holds significant value for the widespread adoption and application of RRAC.

Flow Channel Optimization to Improve the Performance of a Liquid–Gas Ejector for an Intelligent Toilet Spray Bar

Intelligent toilets can effectively remove odors and harmful substances from exhaust gases and wastewater, maintaining a fresh and clean indoor atmosphere, which is beneficial to the indoor environment and human health. Currently, research on intelligent toilets conducted by sanitary ware manufacturers is still in its early stages. Many of the intelligent toilets available on the market exhibit issues such as an excessive oscillation amplitude of the cleaning spray bar, premature breakdown of the water column, and inadequate air intake. The present study involves the analysis and redesign of a cleaning spray bar model for intelligent toilets. Additionally, several optimization schemes concerning the flow channel of the cleaning spray bar are proposed in order to enhance the performance of the liquid–air ejector. The computational fluid dynamics (CFD) technique is utilized to analyze the water flow characteristics within the cleaning spray bar of the intelligent toilet and to compare and evaluate the proposed schemes. The calculation results indicate that, for the same inlet flow rate, the optimal structure the block with a length of L = 1.5 mm and the block positioned (4). The swirl numbers of these two optimized models are 14.8% and 8.3% of the protype, respectively, while their air intake is 133% and 131% of the protype, respectively. The optimized solutions exhibited significant performance improvements when compared to the prototype. The computational results offer valuable insights for optimizing the flow characteristics of the enhanced product.

Research on Nonlinear Behavior of Local High-Performance Concrete Beam-Column Connections.

The seismic performance index of prefabricated structures is generally obtained via experimental analysis. However, in experimental research, it is impossible that every influencing factor can be taken into account. Therefore, the finite element analysis method can be used as a supplementary method for experimental research to carry out parametric analysis of joints. Based on this test, a hysteretic model of steel bars is developed on the ABAQUS platform; meanwhile, the model is used to simulate the seismic analysis of the proposed local reinforced joints. The hysteresis curve obtained via simulation exhibits a high degree of coincidence with the experimental results. Based on the validated model, a detailed parameter analysis of prefabricated local reinforced concrete frame joints is carried out. The analysis results illustrate that the axial pressure ratio at the top of the column has a minimal impact on the joint's performance. Decreasing the stirrup ratio within the core region, enlarging the diameter of the PC steel bar, and increasing the concrete strength that is poured in the keyway and the core region can raise the cumulative energy consumption of the joints, thereby reducing the damage degree of other units and improving the maximum bearing capability of the joints.

Enhancing Math Problem-Solving Skills in Secondary 1 (Grade 7) Students through the Integration of KWDL Technique and BAR Model in Learning Activities

The research entitled The Development of Learning Activity through KWDL Technique Combined with BAR Model to Improve Problem-solving Ability in Math for Secondary 1 (Grade 7) Students made use of a quasi-experimental design wherein the experimental group was exposed to learning activities through the KWDL technique combined with BAR model while the control group learned through traditional. The sample used in this research was 38 Secondary 1 (Grade 7) students from Rizal National Science High School, Rizal Province, Philippines, who studied in the second semester of the 2022 academic year by cluster sampling. The research instruments consisted of 1) learning management plans with learning activities through traditional; 2) learning management plans with learning activities through the KWDL technique combined with the BAR model; 3) problem- solving ability in a Math test. Data analysis included mean, standard deviation, and t-test The results showed that: 1) the problem-solving ability in Math of Secondary 1 (Grade 7) students after studying learning activities through the KWDL technique combined with the BAR model was higher than before learning at a statistical significance level of .05 level; 2) the problem-solving ability in Math of Secondary 1 (Grade 7) students after studying learning activities through traditional was higher than before learning at a statistical significance level of .05; 3) the problem-solving ability in Math of Secondary 1 (Grade 7) students studying learning activities through KWDL technique combined with BAR model was higher than the learning activities through traditional at a statistical significance level of .05.

Cyclic behavior and numerical study of PRC coupling beam with steel truss floor slab

The coupling beam with small span-to-depth ratio is prone to brittle shear failure under the action of earthquake, so it can not play its role as the first line of defense against earthquake. Therefore, this paper proposes a method for calculating the shear bearing capacity of PRC-connected beams with reinforced truss floor plates. A more rational calculation model should be adopted based on its mechanical mechanism. In this study, ABAQUS finite element software is utilized to explore the parameters of PRC-connected beams with steel truss plates, including the span-to-height ratio, reinforcement ratio of the internal steel plate, diameter of upper and lower chord bars, and diameter of abdominal bars. The analysis shows that the span-to-height ratio, steel plate ratio and concrete compressive strength have a significant effect on the seismic behavior of PRC coupling beams with steel truss floor slab. Based on the softened tension-compression bar model combined with the multi-strip model, the theoretical calculation method of the shear capacity of PRC connected beams with steel truss bearing plates is derived. The results of comparison test and simulation verify the accuracy of the calculation results, and provide a design basis for the engineering application of PRC connected beams with steel truss floor plates.

One sight on sound generation and absorption by vortices

Vortices generate sound and absorb sound. A. Powell and M. S. Howe deduced the equations and showed that the exterior product of vortex and local velocity took part in sound generation and absorption. However, it is difficult to image its physical phenomena. In this paper, as one example, the interaction of sound and vortices at the throat of a cavity with grazing flow is investigated by CFD simulation. As the results, it is found that sound absorbing regions and sound generating regions are locally distributed and moving. It is also found that when counterclockwise vortices turn to the left, they absorb sound and when they turn to the right, they generate sound. Based on these results, 'Floating Vertical Bar Model (FVB Model)' is proposed to image the sound generation and absorption phenomena, in which a vortex is simulated as a bar floating vertically on the water surface, because a vortex has coherent structure along its axis like a bar. When a vortex (a bar) is accelerated perpendicular to its axis, pressure fluctuation (water wave) is easily generated. And when sound wave (water wave) shakes a vortex (a bar), sound energy is absorbed by a vortex (a bar) motion.

Biomechanical validation of novel Nuss procedure simulations for patients with various morphological types of pectus excavatum.

A novel Nuss procedure simulation was developed for patients with pectus excavatum considering the displacement of a metal bar and a chest wall model, including the intercostal muscles. However, this simulation was developed for a typical symmetrical patient among the various morphological types of pectus excavatum. Accordingly, this study aimed to validate and confirm the novel simulation for patients with eccentric and imbalanced types, which are severe types of pectus excavatum, considering factors such as depression depth and eccentricity among others. Three-dimensional models of chest walls and metal bars were created for three different types of patients. The rotation-equilibrium displacement and chest wall with intercostal muscles were set according to the methods and conditions of the novel Nuss procedure simulation. The anterior sternal translation and the Haller index derived from the simulation results were compared and verified using medical data from actual postoperative patients. Additionally, maximum equivalent stresses and strains were derived to confirm the suitability of the novel Nuss procedure for each patient type. The severe types had similar precision to the typical type when compared to the actual postoperative patient. Relatively high maximum equivalent stresses and strains were observed on the metal bars and sternum in the severe type, thereby predicting and confirming the biomechanical characteristics of these types. In conclusion, a novel Nuss procedure simulation for severe types was numerically validated. This underscores the importance of biomechanical evaluation through a novel Nuss procedure simulation when planning actual surgeries for severe types of cases.