Plane Of Section Research Articles

Flexural Behavior of Graphite Tailings RC Beams in Chloride Environment

This paper investigates the mechanical properties of graphite tailings concrete beams under various curing environments. The results show that the concentration of graphite tailings has an important influence on the mechanical properties of concrete. Finally, the bending characteristics of the beam and the modified bearing capacity calculation formula are obtained, which provides a theoretical basis and the reference value for the construction of green building materials. Through research, the main innovations and main findings of this paper are as follows: (1) In the three kinds of concrete experimental environment, the fracture load and ultimate load of concrete beams with graphite tailings replacement rate of 20% are the largest. (2) In the three kinds of concrete test environment, when the concrete test beams under the same load, with the increase of graphite tailings replacement rate, the mid-span deflection of concrete beams showed a trend of decreasing first and then increasing. When the replacement rate of graphite tailings sand is 20%, the mid-span deflection of the test beam is the smallest. (3) Through experiments, it is found that the normal section bearing capacity of graphite tailings concrete beams after chloride salt erosion conforms to the plane section assumption. After chlorine salt erosion, the strain of the longitudinal tensile steel bar of concrete beams with different graphite tailings sand replacement rates is the same as that of ordinary concrete beams, and the slope of the strain curve is the same, showing a linear trend. The experimental results show that the replacement rate of graphite tailings sand has an insignificant effect on the strain of steel bars. (4) The Gauss function is used to fit the experimental value of normal section bearing capacity of concrete beam, and the calculation formula of normal section ultimate bearing capacity of graphite tailings sand concrete beam under chloride environment is established. The research results of this paper have significant reference value for the study of mechanical properties of graphite tailings sand concrete components.

Design and Development of a Macro to Compare Sections of Planes to Parts Using Programming with Visual Basic for Applications in CATIA

This article presents an application for educational purposes in the field of engineering graphics, which corrects the dihedral projections of the sections of a plane for a part by comparing the solution provided by the student with that obtained through 3D CAD modelling software. Said application is generated as a macro in CATIA (Computer-Aided Three-Dimensional Interactive Application), which is included as a tool in the ‘Part Design’ module. The code of this macro is written in the CATVBA language, utilizes the CATIA internal editor, and takes advantage of the capabilities offered by Visual Basic for Applications (VBA) in the design of Graphical User Interfaces (GUI). The operation of the macro consists of obtaining the section in the 3D CAD model, projecting it onto three dihedral projections of the part (elevation, plan, and profile), and calculating the visible and hidden lines by means of a numerical process based on dividing the lines into discrete sections. Likewise, to obtain numerical results, the section obtained in CATIA (reference section) is compared with the section provided by the student (section that needed to be corrected) by means of a spreadsheet (Microsoft Excel). The data of the coordinates of the points of the reference section are exported to said spreadsheet as is the data of the coordinates of the section that needed to be corrected, which is contained in a file with a dxf format (Drawing eXchange Format). From these data, by programming the appropriate formulae in the cells of the spreadsheet, the numerical values of the errors are obtained, thereby locating said errors in the dihedral projections of the section which needed to be corrected. Likewise, the application can be programmed to compare the central symmetry of both of the sections.

Behavior of double skin composite core wall subject to biaxial cyclic loads

This study performed a biaxial cyclic test on scaled double skin composite (DSC) core wall. The core wall consisted of two C-shaped DSC shear walls and steel coupling beams (SCBs) connecting the walls. In particular, seismic behavior of the core wall subject to reversed biaxial cyclic load was investigated. The failure mode of the core wall mainly included its local buckling of steel faceplate, fracture of vertical butt welds, fracture of side plate, and concrete crushing at the corners of walls. The lateral shear resistance in its two directions was mutually coupled. Once loaded in one direction, lateral shear resistance in other direction compromised. Due to energy dissipation of SCBs in their Y-direction, hysteresis loop for Y-directional loading was fuller than that for X-directional loading, and equivalent damping ratio of X-direction was 31.91% greater than that of Y-direction at ultimate point. Their initial stiffness in X-direction without SCBs configuration was the highest, and ductility coefficient of X- and Y-directions was relatively close, within 4.63–5.47%. The strain distribution curves along DSC shear wall bottoms of core wall before its peak resistance showed plane section assumption was valid under biaxial lateral load. In particular, DSC core wall high-rise buildings were promoted in this study.

Evaluation of the contour of edentulous jaw sections in the transversal plane and the buccolingual vertical-level disparity in CBCT and panoramic radiography images: a retrospective comparative study

PurposeThis study investigates whether edentulous jaw sections in the planned implant position exhibit jaw contours funnel-shaped or exhibit pronounced retraction of the jaw (unusual jaw contours) in the transversal plane of the three-dimensional (3D) images, not visible in two-dimensional (2D) images.MethodsA total of 335 patients with an edentulous section of the jaw that required dental implants were selected. Anonymised radiologic patients’ data were collected, comprising cone-beam computed tomography (CBCT) images of the edentulous jaw sections. In the first stage, unusual jaw contours were examined, including funnel-shaped or pronounced retraction of the jaw and hypodense regions with an undercut and/or bone deficit. In the second stage, the variation in the height of the alveolar ridge between the lingual and buccal contour in the edentulous jaw sections was assessed.ResultsThe CBCT images of an unusual jaw contour were observed in 8 cases (2.4%) in the maxilla on the left and 10 cases (3%) in the maxilla on the right. In the mandible, a jaw contour deviates in 39 cases (12.1%) on the left side and 39 cases (12.1%) on the right side. A height difference was detected in the upper jaw in 307 cases and the lower jaw in 265 cases. The discrepancy was 2.09 mm (± 2.25 mm) in the maxilla and 3.97 mm (± 3.45 mm) in the mandible.ConclusionsThe CBCT scan provides useful information to avoid complications in the preoperative planning phase and surgical planning in implant dentistry.Graphical

Characterizing the Three‐Dimensional Flow in Partially Vegetated Channels

AbstractPartially obstructed shear flows, such as flows over submerged vegetation patches in river systems, are common in natural environments. Here, a model of a patchily‐vegetated river flow, using staggered arrays of rigid wooden dowels, is used to experimentally characterize the flow. Three‐component point velocity measurements in the cross sectional plane are used to investigate the highly nonuniform, 3D flow field in patchy vegetation and its effect on mass and momentum exchange. The cross‐sectional distribution of mean streamwise velocity varies as a consequence of the bed heterogeneity, being highly dependent on vegetation density. Asymmetric shear layers form at the vertical and lateral edges of the canopy, having different scales within the canopy and in the unvegetated region. Secondary flow cells form in the cross‐plane, with a size that decreases with increasing canopy density. The strength of the upward and downward motions is found to be greater for denser canopies. In addition to the secondary flow, additional rotating cells are observed both above the patch and next to it with increasing canopy density. A triple‐averaging procedure allowed for the quantification of the vertical advective dispersive stresses, which are up to 21% of the total shear stress. This demonstrates the significant role of secondary circulation generated by patchy vegetation in interfacial momentum exchange. Finally, the secondary circulation contribution to vertical scalar transport is estimated to be of the same order as that due to turbulent diffusion, highlighting the importance of understanding the impact of the secondary flow field on aquatic ecosystem function.

Ultrasound liver map technique for laparoscopic liver resections: tips and tricks

Laparoscopic liver resection (LLR) is safer and more advantageous than open surgery regarding morbidity, blood loss, and length of hospital stay. Several radiological studies and liver surgical strategies confirmed that the anatomy of the liver is more complex than what Couinad described. Intraoperative ultrasound (IOUS) has become an indispensable tool to identify the “real anatomy” and to plan a tailored LLR because of wide sub-segmentary variability and lack of external indicators for small functional liver cores. We schematized our standard ultrasound guidance technique during anatomical and non-anatomical LLR as a four-step method called the Ultrasound Liver Map Technique: (1) Compose the three-dimensional mind map to study the relationships between lesions and surrounding vascular elements; (2) create a sketch on the Glissonian using cautery to help the surgeon recall the mind liver anatomy map; (3) check the section plane while proceeding with the transection; and (4) correct the direction of resection plan to ensure a healthy margin concerning the lesion and to point out the pedicle section correctly and not affected structures. Finally, IOUS-Doppler can be used to study the segmental portal flow to assess venous drainage of the remnant parenchyma, avoiding ischemia and increasing the possibility of performing parenchyma-sparing surgery.

Development of model and analysis of one-dimensional movement of ploughshare of subsoiler

Soil medium changes its structure and deforms when the actuating tool of an agricultural machine interacts with the soil. The effect of soil on the performance of the actuating tool can be taken into account through soil density and tensile strength. The model of a plastic medium proposed by Academician Kh.A. Rakhmatulin and simplified equations obtained based on the hypothesis of plane sections were used to describe the movement of soil near the point under finite deformations. It was stated that, depending on the coefficient of internal friction and cohesion of soil, a zone of high soil density could form near the actuating tool of the subsoiler ploughshare, where a significant increase in the resistance force is observed.

ОСОБЕННОСТИ ДЕФОРМИРОВАНИЯ СЕЧЕНИЙ ИЗГИБАЕМЫХ ЖЕЛЕЗОБЕТОННЫХ ЭЛЕМЕНТОВ ПРИ ДЕЙСТВИИ НАГРУЗОК БОЛЬШОЙ ИНТЕНСИВНОСТИ

Many buildings are exposed to special effects of high intensity. When calculating reinforced concrete constructions both for special emergency loads and for seismic loads, the development of plastic strains in reinforcement is supposed just at the design stage. The experimental investigation of plastic deformations influence of the stress-strain state of normal sections of bending reinforced concrete elements has been made. According to the results of experiments, it has been found, that the hypothesis of plane sections is not observed in all cases. The approximation of deformations graph along the cross-section height by the bilinear function, variable during the load process, i.e hypothesis of bilinear sections, is more accurate. The dependence of coefficient A of the hypothesis of bilinear sections on the coefficient of plasticity for reinforcement deformations has been determined based on the results of numerical calculations of beams with symmetric reinforcement and beams without compressed reinforcement in a finite element software package Abaqus. The comparison of obtained numerical results with experimental data has been made, which has shown their satisfactory convergence. The maximum deviation does not exceed 13 %. The assessment of influence of coefficient of hypothesis of bilinear sections on the limit value of coefficient of plasticity for curvature, corresponding to the beginning of the destruction of compressed area of concrete is given.

Hypersurfaces in a Euclidean space with a Killing vector field

<abstract><p>An odd-dimensional sphere admits a killing vector field, induced by the transform of the unit normal by the complex structure of the ambiant Euclidean space. In this paper, we studied orientable hypersurfaces in a Euclidean space that admits a unit Killing vector field and finds two characterizations of odd-dimensional spheres. In the first result, we showed that a complete and simply connected hypersurface of Euclidean space $ \mathbb{R}^{n+1} $, $ n > 1 $ admits a unit Killing vector field $ \xi $ that leaves the shape operator $ S $ invariant and has sectional curvatures of plane sections containing $ \xi $ positive which satisfies $ S(\xi) = \alpha \xi $, $ \alpha $ mean curvature if, and only if, $ n = 2m-1 $, $ \alpha $ is constant and the hypersurface is isometric to the sphere $ S^{2m-1}(\alpha^2) $. Similarly, we found another characterization of the unit sphere $ S^2(\alpha^2) $ using the smooth function $ \sigma = g(S(\xi), \xi) $ on the hypersurface.</p></abstract>

Longitudinal wave propagation in an extended cylindrical body with external Coulomb friction

The propagation of elastic longitudinal waves in an extended cylindrical body located inside an unstrained body and interacting according to the Coulomb law is considered in the article. The problem is studied in a two-dimensional statement; therefore, the friction force (i.e., the interaction conditions) is included in the system of equations as a boundary condition. The Coulomb friction force arises due to the deformation of a cylindrical body. The reliability of numerical calculations is substantiated by solving test cases and comparing the calculations with experimental results. The numerical results obtained are presented in the form of graphs and analyzed. It is shown that the parameters (stresses and strains) of waves propagating in an elastic cylindrical body with external Coulomb dry friction decay with distance. The mechanism for reducing the stress-strain state and wave parameters is explained by the consumption of elastic energy to overcome the friction force that occurs on the contact surface. The results of the two-dimensional problem are also compared with the results of a similar problem in the one-dimensional theory, where the friction force enters directly into the equations of motion. The deviations of the results of the one-dimensional theory are up to 8-15% depending on the accepted values of the friction coefficient, i.e. the violation of the plane section hypothesis taken in one-dimensional calculations amounts to 15%. With a decrease in the radius of a cylindrical body, these deviations are reduced.

ANALISIS KEMAMPUAN MEMAHAMI SUMBU AFINITAS MENGGUNAKAN MAGIC STRAWS PADA MATERI IRISAN BIDANG PADA BANGUN RUANG

Learning material about plane slices in geometric shapes has prerequisite material for the affinity axis. An understanding of the affinity axis can be done with the help of magic straws. The purpose of this study is to provide alternative media to provide an understanding of the affinity axis for students who are constrained by limited computer equipment or computer equipment that is not qualified to install application programs that support learning. This research is a qualitative research. The instruments of this study were observation sheets on the ability to understand the affinity axis and interview guidelines for using magic straws in understanding the affinity axis. Data analysis technique is using data analysis techniques Miles and Huberman. The use of magic straws affects students' abilities regarding the affinity axis, the abilities obtained are students understanding 1) the concept of points that are in a plane, 2) to get an affinity axis, two points that are in a plane that can be connected, 3) a point can be connected with a point of yield an extension of the rib that is still in line with that point, the 4 affinity axes are not only on the base plane, but can also be on the top plane. There are several things that need to be considered, namely 1) selecting straight/not curved pipes when making cubes, 2) using cable ties to mark dots on the ribs so they don't interfere with the student's point of view, 3) when pulling two dots use mattress thread tightly/not loosely, 4) when you have obtained a plane section in the geometric shape, shade the section by connecting it using a mattress thread to the inside of the plane.

Studies on the Performance of Equal Strength Cantilever Beam-Based FBG Acceleration Sensors

Based on the principle of FBG sensing and classical mechanics model of acceleration,the fundamental frequency and acceleration sensitivity coefficient of the fiber Bragg grating (FBG) acceleration sensor are theoretically analyzed in this study. An equal strength cantilever beam-based FBG acceleration sensor was designed based on the vibration frequency of conventional bridges and carried out experimental research. The results show that the fundamental frequency of the sensor increases when the cantilever beam thickness increases, while the sensitivity coefficient decreases. However, when the block mass increased, the fundamental frequency decreased in contrast to an elevated sensitivity coefficient. The experimental findings were found to be in line with the theoretical hypothesis. The sensors had good signal response performance and anti-transverse interference performance. In order to solve the problem of low sensitivity coefficient of sensor, the sensor was optimized and tested following the plane section assumption principle of classical mechanics. The result shows that the fundamental frequency of the optimized sensor remains unchanged, the sensitivity coefficient is increased by 2.6 times. The research provided an FBG acceleration sensor with suitable fundamental frequency, high sensitivity and other excellent performance for bridge monitoring.

Planar Sections of a Surface Close to an Umbilic

We study the intersection between a smooth algebraic surface with an umbilic point and a plane parallel and close to the tangent plane at the umbilic. The problem has its origin in the study of isophote (equal illumination) curves in a 2-dimensional image. In particular, we study the circles which have exceptional tangency to this intersection curve: ordinary tangency at one point and osculating at another; ordinary tangency at three points; and 4-point tangency at a vertex. The centres of circles having ordinary tangency at two points trace out a curve whose closure is the symmetry set of the intersection curve, and the exceptional circles above give respectively cusps, triple crossings and endpoints of this set. We analyse the curves traced out by the contact points and centres of the exceptional circles as the plane approaches the tangent plane at the umbilic. We also briefly discuss the global structure of the symmetry set by means of a typical example.

Optimization of test method for bond performance between steel bar and concrete

The optimization device for the pullout test was designed by mechanical principle. The influence of specimen type on the accuracy of bond performance was studied by test and simulation analysis. Results show that the optimized device improves test accuracy, especially the loading end slip. The circular section specimen has better mechanical performance, more uniform and stable strain variation, and better regularity, which is the preferred section of pullout specimens. The concrete strain distribution does not meet the plane section assumption along the protective layer thickness. In addition, a more practical method for calculating bond stress is proposed.

The algebraic sets of vectors generating planar normal sections of isoparametric hypersurfaces of FKM type

The algebraic sets of vectors generating planar normal sections of isoparametric hypersurfaces of FKM type

A novel isosurface segmentation method using common boundary tests

Visualizing the isosurfaces that represent material boundaries is an important technique for understanding the features of interest in a scalar volumetric dataset. However, one isosurface may contain multiple types of boundaries, i.e., boundaries between different pairs of materials. In this paper, we present a novel isosurface segmentation method that aids in learning structural information of a dataset by separating different types of boundaries in one isosurface. This method uses common boundary tests to classify a point on the isosurface. The test determines whether a point on the isosurface that is at a boundary shared by both the isosurface and a reference isosurface. It uses a gradient-guided sampling approach and is based on material boundary properties. A new region growing algorithm is developed to improve the segmentation results. Our new method can also be used to segment an isosurface that passes through both material boundaries and the interior of a material. Two applications of the new method are also demonstrated in the paper. One is to render and segment section planes to enhance visualization. The other one is to obtain more accurate and meaningful isosurface statistics.

Flexural behavior of pre-damaged and repaired reinforced concrete beams with carbon fiber reinforced polymer grid and engineered cementitious composite

In this study, the flexural behavior of pre-damaged reinforced concrete (RC) beams repaired with carbon fiber reinforced polymer (CFRP) grids and engineered cementitious composite (ECC) was investigated. Fifteen beams were designed and subjected to four-point bending tests. Three types of specimens were tested: undamaged, pre-damaged with removed load (i.e., loaded to the target level and then unloaded), and pre-damaged under sustained load. The main testing parameters were strengthening material (ECC alone, or CFRP grid plus ECC), CFRP grid thickness, main reinforcement ratio, preloaded level, and repairing process. The experimental results showed that most of the repaired beams exhibited flexural failure caused by concrete crushing, and a few others failed by debonding. The proposed repairing technique was effective in enhancing the flexural stiffness and bearing capacity of pre-damaged RC beams. For the repaired beams, the flexural bearing capacities did not significantly decrease as the preloaded level increased from 0 to 0.45 and slightly decreased when the preloaded level exceeded 0.65. A mathematical model based on the plane section assumption was proposed to predict the flexural capacities of the repaired beams, considering whether the load causing the damage was removed or sustained. The predicted capacities were in good agreement with the experimental results.

Fracture prediction of NM450TP wear-resistant steel plates during air bending using a mesoscopic heterogeneous model

A mesoscopic finite element model considering material heterogeneity based on microstructure features was constructed to predict the fracture of NM450TP plates during air bending. The fracture morphology and crack initiation and propagation were specifically addressed from two typical planes of the viewing direction, namely, the section plane orthogonal to the bending axis and the bending (outer) convex surface under tension during bending. The results demonstrated that the model could accurately reproduce the initiation, propagation and final fracture morphology. In the section plane, strain shear bands appeared and then developed into the onset of the initial crack with an inclined angle of 45° to the convex surface. As bending developed, the crack randomly expanded towards the through-thickness direction, ascribed to the interaction between the stress mode and material heterogeneity. In the bending convex surface, the fracture morphology dramatically changed with the relative position between the bending axis and rolling directions. When the bending axis was perpendicular to the rolling direction, a serrated fracture line was formed. When the bending axis was parallel to the rolling direction, a nearly linear fracture line was finally formed along the bending axis.

Decomposing stress wave interference in a cylindrical wooden medium using an inverse deconvolution filter.

Excitation of an embedded waveguide in the cross section plane of a cylindrical structure produces Rayleigh modes propagating primarily in circumferential regions of the propagating medium. In many applications, this region is critical to the overall strength of the structure. Using the through-transmission technique, the Rayleigh mode in cylindrical symmetry produces clockwise and counterclockwise trajectories that interfere with each other at the receiver, producing a composite energy response in the temporal domain that hinders the accurate mode characterization. This work presents a decomposition algorithm consisting of three processing steps: (1) analytical continuous wavelet transforms of the raw waveform; (2) frequency polynomial approximation of the inverse point spread function using L2 norm optimization; and (3) derivation of the inverse deconvolution filter via the dual derivative operator. This work demonstrates the mathematical formulation and algorithm implementation with numerical and empirical validations. The proposed decomposition filter can achieve the overall time and energy estimation accuracy with a relative root mean square error of 0.07. Its broader impact will enhance the parametric estimation of the diagnostic stress wave for material characterization.

Nuclei and tracts in the pretectum and associated tegmentum of crocodiles.

In all vertebrates, the pretectum and associated tegmentum arise from prosomere 1, but the adult derivatives of these embryonic regions are not well defined in reptiles-especially in crocodiles, the reptilian group most closely related to birds. Despite its importance in vision and visuomotor behavior, descriptions of the pretectum in crocodiles are brief and photographs are lacking. To fill this gap in knowledge, the pretectum and associated tegmentum were examined in two crocodilians, Caiman crocodilus and Alligator mississippiensis, using a variety of histological stains in all three traditional planes of section. These observations were compared with similar studies in other reptiles and birds. These comparisons were hampered by differences in nomenclature and limited data. Nevertheless, pretectal nuclei in receipt of retinal input in crocodiles, other reptiles, and birds were the most easily identified when compared with the present analysis. Despite identifying the traditional nuclei comprising the pretectum of crocodiles, other areas remain to be characterized. Nevertheless, knowledge gained from this description will aid further investigations of this brain region in crocodiles and other reptiles as well as provide a reference for developmental studies in crocodiles.