Cross-sectional Shape Research Articles

Effect of restrained versus free drying on hygro-expansion of hardwood and softwood fibers and paper handsheet

Earlier work on the hygro-expansion of paper states that the larger hygro-expansivity of freely compared to restrained dried handsheets is due to structural differences between the fibers inside the handsheet. To study this hypothesis, first, the hygro-expansion of freely and restrained dried, hardwood and softwood handsheets has been characterized. Subsequently, the transient full-field hygro-expansion (longitudinal, transverse, and shear strain) of fibers extracted from these handsheets was measured using global digital height correlation, from which the micro-fibril angle was deduced. The hygro-expansivity of each individual fiber was tested before and after a wetting period, during which the fiber’s moisture content is maximized, to analyze if a restrained dried fiber can “transform” into a freely dried fiber. It was found that the longitudinal hygro-expansion of the freely dried fibers is significantly larger than the restrained dried fibers, consistent with the sheet-scale differences. The difference in micro-fibril angle between the freely and restrained dried fibers is a possible explanation for this difference, but merely for the hardwood fibers, which are able to “transform” to freely dried fibers after being soaked in water. In contrast, this “transformation” does not happen in softwood fibers, even after full immersion in water for a day. Various mechanisms have been studied to explain the observations on freely and restrained dried hardwood and softwood, fiber and handsheets including analysis of the fibers’ lumen and cross-sectional shape. The presented results and discussion deepens the understanding of the differences between freely and restrained dried handsheets.

Analysis of Mechanical Properties and Structural Analysis According to the Multi-Layered Structure of Polyethylene-Based Self-Reinforced Composites.

In this research, a self-reinforced composite material was manufactured using a single polyethylene material, and this self-reinforced composite material has excellent recyclability and is environmentally friendly compared to composite materials composed of other types of material, such as glass fiber reinforced composites (GFRP) and carbon fiber reinforced composites (CFRP). In this research, the manufactured self-reinforced composite material consists of an outer layer and an inner layer. To manufacture the outer layer, low density polyethylene (LDPE) films were laminated on high density polyethylene (HDPE) fabrics and knitted fabrics, and composite materials were prepared at various temperatures using hot stamping. A 3D printing process was utilized to manufacture the inner layer. After designing a structure with a cross-sectional shape of a triangle, circle, or hexagon, the inner layer structure was manufactured by 3D printing high-density polyethylene material. As an adhesive film for bonding the outer layer and the inner layer, a polyethylene-based self-reinforced composite material was prepared using a low-density polyethylene material. Input data for simulation of self-reinforced composite materials were obtained through tensile property analysis using a universal testing machine (UTM, Shimadzu, Kyoto, Japan), and the physical property values derived as output data and actual experimental values were obtained. As a result of the comparison, the error rate between simulation data and experimental data was 5.4% when the shape of the inner layer of self-reinforced composite material was a hexagon, 3.6% when it was a circle, and 7.8% when a triangular shape showed the highest value. Simulation in a virtual space can reduce the time and cost required for actual research and can be important data for producing high-quality products.

The Effect of Bleaching Agents on Color Change in Different Section Shapes in Beech And Fir Woods

Aim of study: It is an investigation of the effects of bleaching processes on the color change in the wood of tree species. Tree species Eastern Beech (Fagus Orientalis Lipsky.) and Eastern Black Sea Fir (Abies Nordmanniana subsp.) were used in the study. Sodium hydroxide-hydrogen peroxide, oxalic acid, peracetic acid diluted 1/3, peracetic acid diluted 1/6 were used as bleaching agents. Trial samples were prepared in accordance with standards and color change measurements were made.
 Area of study: Surface treatments on wooden materials
 Material and methods: In the study, two wood species and one varnish type were used; Color changes were tested by applying various bleaches to the wooden material by rubbing method.
 Main results: As a result of the study, differences were observed in all cross-section shapes in beech wood bleaching measurements with 1/6 diluted peracetic acid, and differences were observed in cross-section shapes in fir wood bleaching measurements. The best bleaching of fir wood was achieved with peracetic acid.
 Main results: As a result of the study, differences were observed in all cross-section shapes in the beech wood bleaching measurements with 1/6 diluted peracetic acid, and in the cross-section shapes in the fir tree bleaching measurements. The best bleaching of fir wood was achieved with peracetic acid.
 Highlights: The bleaching process allows the wooden material to easily acquire a homogeneous color. Since the cell arrangements are different in different cross-sectional shapes, the bleaching rates are different from each other. While there is not much difference in the color changes in the wood material when bleached with oxalic acid, the samples are bleached as a result of bleaching with sodium hydroxide-hydrogen peroxide and peracetic acid. Significant changes have occurred in color changes. The reason for this difference is due to the different degrees of corrosion of bleaching agents.

An experimental study on structural performance of reinforced concrete beams strengthened for combined flexure and shear by using NSM-GFRP strips

Near surface mounted fiber reinforced polymer (NSM-FRP) technique is the latest & most effective techniques used in strengthening the existing structural components, which requires strengthening against increased service loads, faulty design, environmental effects, etc. In the past, many researches on NSM technique have been carried out by using different cross-sectional shapes & dimensions of FRP materials to strengthen for shear & flexure. In the present experimental study, the behaviour of R.C. beams strengthened for combined flexure & shear studied. The beams of 150x150x700 mm size with M30 grade of concrete & Fe500 steel were considered. The control beams (unstrengthened) & strengthened beams using GFRP (Glass fibre reinforced polymer) strips were subjected to three point loading to study the behaviour of beams in combined shear & flexure. The main objectives were to assess the behaviour of strengthened beams with control beams & to study the influence of the orientation of shear strips. The beams were studied for the failure characteristics, yield & ultimate load carrying capacity, stress-strain behaviour, deflection, & crack patterns. From the test results, it’s been observed that, the load carrying capacity of the strengthened beams were increased, the improved in deflection, when compared to the control beams. The ultimate load carrying capacity of beams with shear strip orientation of 45°, 60° & 90° were increased by 50.3%, 39.3% & 25% respectively, compared to the control beams. This NSM strengthening technique can be advantageous & suitably adopted to enhance the load carrying capacity of the beams.

Analysis of the Influence of Inlet Position on the Transverse Homogeneity of Slot Coating

Slot coating is a widely used method for high performance material production. Coating quality mainly depends on whether the coating liquid can be evenly coated on the material. To be evenly coated, the coating liquid is required to have good transverse velocity uniformity at the exit of the die. The position of the inlet of the die has an important effect on the horizontal uniformity of the die. In order to quantitatively analyze the influence of the inlet position of the die head on the transverse uniformity of the die, we respectively simulated the internal flow field of two different shapes of uniform cross section die head, and finally got the preliminary law. It is found that no matter the shape and structure of the cavity, the transverse uniformity of the coating can be greatly improved using the intermediate feeding method.

Numerical investigation of cavitation in periodontal Pockets: Insights for enhancing cleaning efficiency

Ultrasonic dental scalers are indispensable instruments for efficient dental cleaning through the generation of cavitation. To gain valuable insights and enhance the cavitation cleaning effects, a numerical investigation is conducted using the finite element method via ABAQUS. Numerical results are compared with the experimental cavitation image for a scaler undergoes vibrations near a wall. We then analyse how the amplitude, frequency, and cross-sectional shape of the scaler affect cavitation generation. Numerical results indicate that cavitation is more pronounced for a scaler oscillating near a nearly rigid boundary than a soft boundary. It increases with the vibration amplitude because of higher ultrasonic energy transferring to the liquid and generating stronger pressure waves. The resonant frequency of the scaler coincides with the maximum cavitation and scaler tip amplitude. Reducing the dimension of the cross-section of the scaler in its oscillation direction increases both the scaler tip amplitude and the cavitation generated. This finding offers a potential design approach for enhancing the scaler cavitation and its cleaning effects. These insights provide practical guidance for optimising dental scaler settings, which can improve oral hygiene and prevent complications related to dental implants.

우리나라 남해안의 쪽구들 주거지 등장과 연해주 초기철기시대 문화

In this paper, we investigated the relationship with Neukdo by comparing and analyzing the ridge dwellings of the Tuanjie-Krounovka culture in the Russian Maritime Province and the bone mound remains of the Yankovsky culture. The plan and cross-sectional shapes of the early Ondol identified here are the most common structures in Nekdo Island. Most of the stone pits were installed around the 2nd century BC, when the period of the Nekdo ruins began. A large amount of deer bones, antlers, and bone fragments are produced on Nekdo Island, but most people were of the opinion that they could not be supplied from the island. In particular, there was an opinion that the two ulna stabs were not an important item in Nekdo, where small iron knives were used, but in the Yankovsky culture, they were mainly used along with iron knives. Also, ornaments with patterns can be seen in the Jankovky culture. Fishing hooks, knives, bone needles, and split harpoons are commonly found. Nekdo’s ‘bone sword’ may be a reproduction of the stone spear of the Yankovsky culture. ‘boggol’ were excavated, but only a small number of them were used, so they were not mainly used. The early Ondol dwellings and bone carvings found on Nekdo Island are a characteristic of the Tuanjie- Krounovka culture and Yankovsky culture of the Maritime Province and the northeastern region, and they provided deer meat and bone carving equipment to Nekdo Island. To prevent corruption, they would have lived on Nekdo Island only in the winter. In the ruins of Nekdo Island, the early Ondol dwellings used for wintering are located on the shell floor or nearby. This shows that decomposition of shellfish was not possible in severe summer and was possible only in winter. The relationship between culture Tuanjie-Krounovka and Yankovsky, which occupied the coast of the Maritime Province since the 3rd century BC, should be studied in the future. In addition, research on the burial methods of Yankovsky culture will be revealed through a separate paper.

Modeling the Stress State of Non-Thin Cylindrical Shells with a Perturbed Cross-Sectional Shape

Modeling the Stress State of Non-Thin Cylindrical Shells with a Perturbed Cross-Sectional Shape

Measurements of natural convective heat transfer of the inclined torus

Experiments were conducted to investigate the natural convective heat transfer characteristics of an inclined torus. The Rayleigh numbers ranged from 4.54 × 106 to 1.23 × 108 and the inclination angle was varied from 0° to 80° Mass transfer experiments were performed based on the analogy between heat and mass transfer using the CuSO4H2SO4 copper electroplating system. The heat transfer of the inclined torus exhibited a trend similar to that of an inclined cylinder, with a gradual decrease in heat transfer with the inclination angle due to the variation of vertical cross-sectional shape. However, the inclined torus demonstrated better heat transfer performance than an inclined cylinder as the curved structure interrupts the formation of the stable boundary layer underneath the torus. The flows were visualized by Particle Image Velocimetry (PIV) and the heat transfers, by the electric plating patterns. New correlations were proposed to predict the heat transfer coefficient of the inclined torus as a function of Rayleigh number, inclination angle, and toroidal ratio.

Improving the aerodynamic performance of Trans-Tokyo Bay Bridge using reliability-based design optimization

ABSTRACT The Vortex-Induced Vibration (VIV) phenomenon can cause fatigue damage. Usually, countermeasures are implemented to mitigate the VIV amplitudes. However, its cost is high. Therefore, approaches have been developed to avoid VIV at an early stage of design. Most such studies have focused on avoiding the coincidence of the vortex shedding frequency with the natural frequency of the structure and delaying VIVs by including geometrical changes to the leading and trailing edges in order to divide the oncoming flow. In this study, a new framework is proposed to find the optimal deck cross-sectional shape of Trans-Tokyo Bay Bridge, based on Reliability-Based Design Optimization (RBDO) and aiming to mitigate the VIV effects under uncertainty. Validation of the optimal designs is conducted via Computational Fluid Dynamics (CFD) simulations for different target reliability indices.

Dimensionless plate height is unsuitable for comparing chromatographic columns

Dimensionless plate height (h) is differently defined for the columns with different type of internal filling (internal support structure). It is h = H/d for open columns (d is the internal diameter), h = H/dp for packed columns (dp is the particle size), h = H/ddom (ddom is the domain size) for columns with other filling (e.g., monolithic, pillar array). The plate height (H) and the column kinetic performance in general depend on the flow channels through the column filling – on their cross-sectional dimensions (dchan), shape, and wall porosity. Other than through their effect on the flow channels, the dimensions of skeleton of the filling and the ddom do not affect H. Parameters d, dp and ddom cannot be found from external measurements of a column as a ”black box” separation device and, therefore, are unmeasurable subjective metrics, and, therefore, so is h. Moreover, in some fillings (e.g., monolithic, pillar array) ddom can be chosen independently of dchan. By increasing ddom without changing dchan, one can make h as small as desired with no effect on H and on the column kinetic performance in general. This implies that h does not represent column performance and cannot be used for comparing differently structured column.In this report, previously introduced measurable (objective) performance metrics – the kinetic performance factor (q) and the quality factor (qmax) are described and evaluated. The latter is suitable for comparing differently structured columns. A column practically achievable performance depends not only on qmax, but on the largest pressure that a column can tolerate, the narrowest flow channels that can be manufactured and other practical factors. Practically achievable performance of several column types is compared in this report.

Geomechanical Model Test on the Zonal Disintegration of Deep Tunnel in Jinping II Hydropower Station

Zonal disintegration is commonly encountered during the construction of tunnels at large depth. To study the formation and evolution mechanism of zonal disintegration in deep tunnels, a geo-mechanical model test is conducted under three-dimensional condition. The results reveal that: 1) with the proceeding of tunnel excavation, the displacements and the stresses around the tunnel present oscillating variation with alternating peak and trough. 2) Four annular rupture zones can be found around the tunnel, where the distance between the outermost rupture zone and the tunnel periphery is approximately 9.6 m. 3) The rupture zone first forms on the sidewalls of the tunnel, and then gradually develops to the interior of the rock mass until a complete ring-shaped rupture zone is formed. 4) The evolution of zonal disintegration is affected by the shape of cross section. The reproduction of zonal disintegration in laboratory can effectively reveal the formation mechanism and develop the control measures. The results obtained will provide important scientific basis for the safety construction of deep underground engineering.

Confinement-based direct design method for fibre reinforced polymer confined CFST short columns

The paper presents a detailed analysis of the behaviour of circular and square concrete filled steel tube (CFST) short columns strengthened externally with carbon or glass fibre reinforced polymer sheets (CFRP or GFRP, respectively). A thorough review of existing test information is presented and discussed, and the most salient parameters in terms of the overall strength are identified. There are a large number of influential and inter-related parameters which affect the load-carrying capacity, including the geometry, cross-sectional shape, type of steel, concrete strength, boundary and loading conditions, and type of FRP. It is shown that existing design approaches do not reliably predict the strength for the full range of possible parameters. Therefore, this paper proposes a new design model to calculate the axial compressive strength of FRP-confined concrete filled steel tubular (CFST) short columns with either a circular or square cross-section. The method accounts for the various complexities which affect the behaviour, yet presents a user-friendly, performance-based design expression. It is based on an evaluation of the lateral confining pressure provided by the both the FRP and the steel tube to the concrete core. This is employed in the confinement-based direct resistance calculations. The paper validates the approach by comparing its capacity predictions with a large database of experimental results and alternative design models available in the literature. The results show that the proposed model provides much accurate strength predictions with greater reliability for the full range of parameters examined, than existing methods.

The safe zone of distal fibula was determined based on the classification of lateral malleolus fossa

BackgroundLateral malleolus fractures are very common, and the distal fibular geometry is complex. This study aimed to classify the lateral malleolus fossa (MF) into different types by characterizing the lateral MF imaging morphology and exploring the relationship between the lateral MF and internal fixation position after distal fibula fractures.MethodsAnteroposterior CT reconstruction was performed on 248 subjects. After reconstruction, the deepest point of the lateral MF was located, and then, the cross-sectional shape of the lateral MF was observed and classified.ResultsAccording to the morphology of the CT cross section, the lateral MF was divided into three types: type C (43.1%), type V (32.2%), and type Flat (24.7%). Type V (3.98 ± 0.82) was significantly longer than type C(2.83 ± 0.54) and type Flat (1.84 ± 0.42) in cd. Similarly, in ∠α, Type Flat(136.31 ± 9.63) was the largest, followed by type C (116.51 ± 8.79), and type V (89.31 ± 9.07) was the smallest. Other measurements were not found any significant differences between the above.ConclusionAccording to the morphology of the CT cross section, the lateral MF was divided into three types: type C, type V and type Flat. Type V is most likely to be invaded when fixing the distal fibula. Screws less than 9 mm should be selected when fixing, and screws no more than 10 mm should be selected when there are type C and type Flat of MF.

Gas transport law in inorganic nanopores considering the influence of cross section shape and roughness

To study the gas transport characteristics in rough inorganic nanopores, the effective pore size models of circular and rectangular nanopores are established, considering the influence of the adsorption water film, rock surface roughness, effective stress and the shape of the nanopore section. On this basis, the gas flow patterns are coupled, and the gas transport models in circular and rectangular rough nanopore are established respectively. The effectiveness of this model is verified by comparing it with experimental data and other scholars' models. At the same time, the effects of roughness, cross-sectional shape, cross-sectional aspect ratio, and humidity on gas migration are analyzed. The results indicate that regardless of the cross-sectional shape, an increase in roughness will lead to varying degrees of reduction in the apparent permeability of micro and nano pores. When the pressure is small, the influence of roughness on the gas permeability of rectangular cross-section nanopores is greater than that of circular cross-section nanopores. As the pressure increases, the influence of roughness on the gas permeability of rectangular and circular cross-section nanopores tends to be the same. The influence of roughness on the water saturation of rectangular cross-section nanopores is less than that on circular cross-section nanopores.

Covariation between the shape and mineralized tissues of the rib cross section in Homo sapiens, Pan troglodytes and Sts 14.

Studying rib torsion is crucial for understanding the evolution of the hominid ribcage. Interestingly, there are variables of the rib cross section that could be associated with rib torsion and, consequently, with the morphology of the thorax. The aim of this research is to conduct a comparative study of the shape and mineralized tissues of the rib cross section in different hominids to test for significant differences and, if possible, associate them to different thoracic morphotypes. The sample consists of the rib cross sections at the midshaft taken from 10 Homo sapiens and 10 Pan troglodytes adult individuals, as well as from A. africanus Sts 14. The shape of these rib cross sections was quantified using geometric morphometrics, while the mineralized tissues were evaluated using the compartmentalization index. Subsequently, covariation between both parameters was tested by a Spearman's ρ test, a permutation test and a linear regression. Generally, P. troglodytes individuals exhibit rib cross sections that are rounder and more mineralized compared to those of H. sapiens. However, the covariation between both parameters was only observed in typical ribs (levels 3-10). Although covariation was not found in the rib cross sections of Sts 14, their parameters are closer to P. troglodytes. On the one hand, the differences observed in the rib cross sections between H. sapiens and P. troglodytes might be related to different degrees of rib torsion and, consequently, to different thoracic 3D configurations. These findings can be functionally explained by considering their distinct modes of breathing and locomotion. On the other hand, although the rib cross sections belonging to Sts 14 are more similar to those of P. troglodytes, previous publications determined that their overall morphology is closer to modern humans. This discrepancy could reflect a diversity of post-cranial adaptations in Australopithecus.

Calibrating a hydrodynamic model using water surface elevation determined from ICESat-2 derived cross-section and Sentinel-2 retrieved sub-pixel river width

Accurate observations of river water surface elevation (WSE) are critical for hydrodynamic (HD) model calibration in poorly gauged regions. This study presents a new river WSE retrieval approach that combines ICESat-2 derived cross-sections and Sentinel-2 observed sub-pixel river widths to achieve an effective HD model calibration. The unknown channel Manning coefficient, river bed elevation and cross-sectional shape in the HD model are calibrated simultaneously through a Bayesian optimization algorithm. The complete workflow is implemented in a flood-prone reach in Yiluo River basin. Results show that the WSE retrieved by the new approach has a higher spatiotemporal resolution in narrower rivers than that of Sentinel-3 altimetry derived WSE, and the root-mean-square error (RMSE) varies from 0.25 to 0.59 m against in-situ WSE. The HD model calibrated by WSE retrieved by the new approach simulates the WSE with RMSE of 0.36 m and the flood extent with critical success index (CSI) of 0.60 in validation, outperforming the results of the HD model calibrated by Sentinel-3 altimetry derived WSE, with corresponding results of 0.49 m and 0.58, respectively. Additional case studies in the Maqu and Lingkou reaches further demonstrate the applicability of the WSE retrieval approach proposed in this study for HD model calibration in different types of rivers. This study highlights the potential of the proposed WSE retrieval approach in HD model calibration to improve flood forecasting in poorly gauged regions.

Nitinol advancements in endodontics: Heat treatment and surface functionalization of NiTi instruments

Nitinol, a nickel-titanium alloy known for its exceptional properties of shape memory, superelasticity, and biocompatibility, has revolutionized the field of endodontics. This article explores the evolutionary journey of Nitinol in endodontics, highlighting its historical inception and subsequent integration into dental instruments. The article delves into pivotal advancements such as heat treatment and surface functionalization, showcasing their transformative effects on the mechanical properties and biocompatibility of Nitinol instruments. The discussion encompasses terms related to NiTi file design, including helical flute angles, pitch, cutting edges, rake angles, radial lands, cross-sectional shapes, and taper. Moreover, the article elucidates the modes of movement employed by NiTi files, including continuous rotary motion, reciprocating motion, and axial motion, emphasizing their significance in enhancing precision and minimizing risks. Through an exploration of Nitinol's evolution and its impact on endodontic procedures, this article underscores the symbiotic relationship between innovative materials and the evolving landscape of dentistry.

Enhancing slender reinforced concrete columns with G-FRCM jackets: Experimental and numerical analysis of confinement effects and cross-sectional shape impact

This research investigates the use of Glass Fabric Reinforced Cementitious Matrix (G-FRCM) as a confinement material for slender reinforced concrete (RC) columns with slenderness ratios greater than the slenderness criterion for isolated members. An experimental program was conducted on six slender RC columns, including two control and four G-FRCM-confined specimens. The results demonstrated that the G-FRCM strengthening strategy was highly effective, with the compression resistance of the columns increasing by 22.1% and 55.5% for one and two layers of G-FRCM, respectively, compared to the control samples. The experimental results were used to implement and validate the non-linear behaviour of G-FRCM-confined RC columns, employing the Finite Element Method (FEM) through the ABAQUS software. The results, in terms of compression strength, were consistent compared to the experiments, with a difference of less than 5%. Additionally, a parametric investigation has also been conducted to analyse the influence of the slenderness ratio on the response of confined columns. The findings of this study contribute to the understanding of the use of G-FRCM as a highly effective confinement material for RC columns.

Design and evaluation of compressive properties of 3D-printed PLA stochastic open-cell foam

The deformation characteristics and mechanical behaviour of 3D-printed stochastic open-cell foam structures were experimentally studied under a quasi-static compression test. PLA foam specimens with irregular cell geometry, variable strut sections and prescribed relative density are constructed numerically using the Voronoi diagrams and prepared with fused deposition modelling. The design procedure allows controlling the strut topology easily, which makes the geometrical model suitable for studying the effect of local morphological characteristics on the mechanical performance of open-cell foam material. The effect of different morphological characteristics on the compressive mechanical behaviour of the fabricated PLA foam was examined in detail. Compression experiments prove that the mechanical properties are significantly dependent on the relative density and strut section shape. The main mechanical properties of the 3D-printed PLA foams for different cross-sectional shapes of struts were obtained via the energy-efficient method and expressed with the two common formulas existing in the literature.