Flat Part Research Articles

Parallelism measurement method for nontransparent flat parts.

Nontransparent flat parts with weak rigidity are widely used in precision physics experiments, aerospace, and other fields in which parallelism is required. However, existing methods cannot meet requirements due to the limitation of measurement size and accuracy. This paper proposes a new method for measuring parallelism of nontransparent flat parts with high accuracy and then builds a submicrometer-level parallelism measuring system. The 3D model of the whole part is reconstructed by thickness and flatness, which are measured respectively. Subsequently, parallelism is evaluated by the principle of minimum directional zone. The method is verified by an experiment with a thin copper substrate sized ⊘200mm×2.48mm on the parallelism measuring system. The experiment result shows that the part's parallelism is 7.41 µm, and the expanded uncertainty of parallelism measurement system is 0.34 µm, k=2.

ANALYSIS OF MECHANICAL METHODS OF CONTROLLING THE POSITION OF FLAT SHOE PARTS BY SURFACE PROPERTIES

The article considers ways to solve the problem of orientation of flat parts with different properties of surfaces that come to the working position of technological equipment. Mechanical methods of controlling the position of flat parts of footwear on the properties of surfaces are based on the use of asymmetry of their frictional properties or the magnitude of surface irregularities. In some cases, in the process of position control with the help of devices that implement these methods, it is possible to simultaneously transport the part to the working position of the process equipment or to the position of reorientation. Frictional properties of surfaces of any materials are characterized by the coefficient of friction, which depends on the elastic properties of the material, surface roughness, specific load and many other parameters that characterize the molecular interaction of surfaces in the contact zone. Most shoe materials have different frictional properties of the front and back surfaces. This provides the ability to automatically orient parts made of such materials on the basis of “front side – reverse side” using the differences in the frictional properties of the surfaces of the part. The use of rolls as sensors to control the position of flat shoe parts on the frictional properties of surfaces and simultaneous transportation of parts from the control position to the loading or reorientation position greatly simplifies the control operation, increases productivity and reliability of control devices. For correct installation of details on technological processing it is necessary to reveal their position and, in case of incorrect, to reorient. For this purpose, devices for position control on frictional properties and asymmetry of surface topography, as well as their design calculations are proposed.

Vision measurement for flat parts based on local line-angle contour segmentation

In order to detect the size information of complex flat parts, this paper proposed a method for flat part measurement based on local line-angle contour segmentation. After processing the images taken by photos and edge detection, we obtained sub-pixel part contours. Then, the local line-angles of the part contours were calculated, processed and analyzed, and so on the features of the connection between the geometric primitives of different line segments on its contour were obtained. The segmentation of the part contour came true. Next, a line segmentation error model was built, and then we got the parameters of the contour segment and the key points of the components by iterative fitting the segmented line and pinpointing the location of the segmentation. Afterwards a binocular vision model provided the spatial point cloud of the key points. As a result, the size information of the parts were acquired after analyzation and calculation. The present method can successfully measure the multiple size of the complex flat parts, which is more efficient and precise.

Tiny hole inspection of aircraft engine nacelle in 3D point cloud via robust statistical fitting

In the aircraft manufacturing industry, drilling hole inspection is a vital task for the noise reduction ability and the aircraft structure stability. Due to the complexity of the inner surface of the engine nacelle, inspecting drilling holes of a small size and a large number is fairly challenging. In this paper, we propose a framework for automatic hole inspection on composite flat parts. The raw data of traditional 3D laser scanning usually contain considerable noise and outliers, which has a great influence on tiny hole inspection. First, to perform measurement efficiently and to get raw data of good quality, we design a measurement platform to perform automatic measurement on a preset path. Instead of applying common boundary detection methods, we design a method to detect boundary points by evaluating the boundary possibility of each point, which is more likely to detect the points on a real hole boundary than noise. Based on the characteristics of laser scanning data, we then combine an effective algebraic circle fitting method with an iterative fitting strategy and develop a robust circle fitting method. The improved circle fitting method is capable of estimating a circle closest to the ground truth. Experiments demonstrate that our fitting method performs better than other common fitting methods for comparison under both synthetic and real scanning data.

Thermal Flaw Detection Scanner for Testing Large-Sized Flat Products Made of Composite Materials

A self-propelled thermal flaw detector has been developed for testing large-sized flat parts by means of thermal scanning that provides higher efficiency and test performance than conventional thermal testing scheme over individual zones. The flaw detector is designed to detect delaminations, impact damage, and foreign inclusions in composite materials and can be used to test for corrosion in metal shells, providing continuous monitoring with a performance of up to 20 m2/h.

Appropriate Window Function and Window Length in Multifrequency Velocity Estimator for Rapid Motion and Locality of Layered Myocardium.

The heart wall has a multilayered structure and moves rapidly during ejection and rapid filling periods. Local strain rate (SR) measurements of each myocardial layer can contribute to accurate and sensitive evaluations of myocardial function. However, ultrasound-based velocity estimators using a single-frequency phase difference cannot realize these measurements owing to insufficient maximum detectable velocity, which is limited by a quadrature frequency. We previously proposed a velocity estimator using multifrequency phase differences to improve the maximum detectable velocity. However, the improvement is affected by a spatial discrete Fourier transform (DFT) window length that represents the locality of the velocity estimation. In this article, we theoretically describe that shortening the window increases the interference between different frequency components and decreases the maximum detectable velocity. The tradeoff between the maximum detectable velocity and the window length was confirmed through simulations and a water-tank experiment. Under the tradeoff, the Hanning window, which was used in previous studies, is not always appropriate for the local measurement of the velocity, which sometimes exceeds 100 mm [Formula: see text] depending on the subject, direction of the ultrasound beam to the heart wall, and cardiac periods. In the in vivo measurement with the short window, the Tukey window with a large flat part that has a high-frequency resolution and ameliorates the discontinuity at both edges of the windowed signal was appropriate to measure the maximum velocity. This study offers the potential for local measurements of each myocardial layer using the multifrequency velocity estimator with the appropriate window function and window length.

Сроки проведения витрэктомии при проникающих ранениях глазного яблока

Purpose. Analysis of the results and identification of the optimal timing of vitrectomy for penetrating wounds of the eyeball. Material and methods. For the study, 15 patients with 15 eyes were selected with a diagnosis of penetration injury (scleral or corneoscleral) within the boundaries of the flat part of the ciliary body, hemophthalmos without retinal detachment and lens damage. All patients underwent vitrectomy for hemophthalmos. The patients were divided into 3 groups: 1 group of 5 people – vitrectomy was performed on the 2 nd day after admission to the ophthalmology department (primary surgical treatment of pan + vitrectomy); 2 group of 5 people – vitrectomy was performed 12-14 days after primary surgical treatment; 3 group of 5 people – vitrectomy was performed after 1 month or more after a penetrating wound. Results. The optimal timing of vitrectomy in penetrating wounds of the eyeball complicated by hemophthalmos, without the presence of retinal detachment and damage to the lens, has been determined. Conclusion. The analysis of the results of surgical treatment indicates the need for a comprehensive examination of patients with penetrating eye wounds. It is necessary to refrain from early vitrectomy, it is also dangerous to have a blood clot in the vitreal cavity for a long time due to the traction effect on the retina. Keywords: penetrating wound, vitrectomy, hemophthalmos, retinal detachment.

Probability Model of Riding Behavior Choice of Two-Wheelers under the Influence of the Subsidence Area of a Manhole Cover

To objectively evaluate the influence of the subsidence area of a manhole cover on the riding behavior of two-wheeler riders in urban bicycle lanes, a probability model of riding behavior of two-wheeler riders was established. The main factors influencing the probability of riding behaviors under the condition of the subsidence area of a manhole cover are investigated. Based on the field data of 10 survey sections in Guilin, the regression models between the selected probability of independent riding behavior, combined riding behavior and the main influencing factors are respectively established by using the multiple regression analysis method. The results show that the selected probabilities of deceleration riding behavior and original-speed riding behavior have a linear regression relationship with the subsidence depth of the manhole cover and the lane integrity. The subsidence depth of manhole covers is positively correlated with the probability of deceleration riding behavior and negatively correlated with the probability of original-speed riding behavior; lane integrity is positively correlated with both the probability of deceleration riding behavior and the probability of original-speed riding behavior. The data goodness-of-fit value for the relevant influence factors in the two models is 0.941 and 0.900, respectively. The probability of acceleration riding behavior has a linear regression relationship with the lane integrity and section flow. Lane integrity is negatively correlated with the probability of acceleration riding behavior and positively correlated with section flow. The data goodness-of-fit value for the relevant influence factors is 0.821. The probabilities of straight riding behavior and detour riding behavior have a linear regression relationship with the subsidence depth of manhole covers and the minor width of the flat part. The subsidence depth of a manhole cover is negatively correlated with the probability of straight riding behavior and positively correlated with the probability of detour riding behavior. The minor width of flat part is negatively correlated with the probability of straight riding behavior and positively correlated with the probability of detour riding behavior. The data goodness-of-fit value for the relevant influence factors in the two models is 0.601 and 0.603, respectively. The results provide the theoretical basis for the evaluation of the severity and optimization design of the subsidence of manhole covers in urban bicycle lanes.

Dev2PQ: Planar Quadrilateral Strip Remeshing of Developable Surfaces

We introduce an algorithm to remesh triangle meshes representing developable surfaces to planar quad dominant meshes. The output of our algorithm consists of planar quadrilateral (PQ) strips that are aligned to principal curvature directions and closely approximate the curved parts of the input developable, and planar polygons representing the flat parts of the input that connect the PQ strips. Developable PQ-strip meshes are useful in many areas of shape modeling, thanks to the simplicity of fabrication from flat sheet material. Unfortunately, they are difficult to model due to their restrictive combinatorics. Other representations of developable surfaces, such as arbitrary triangle or quad meshes, are more suitable for interactive freeform modeling but generally have non-planar faces or are not aligned to principal curvatures. Our method leverages the modeling flexibility of non-ruling-based representations of developable surfaces while still obtaining developable, curvature-aligned PQ-strip meshes. Our algorithm optimizes for a scalar function on the input mesh, such that its isolines are extrinsically straight and align well to the locally estimated ruling directions. The condition that guarantees straight isolines is non-linear of high order and numerically difficult to enforce in a straightforward manner. We devise an alternating optimization method that makes our problem tractable and practical to compute. Our method works automatically on any developable input, including multiple patches and curved folds, without explicit domain decomposition. We demonstrate the effectiveness of our approach on a variety of developable surfaces and show how our remeshing can be used alongside handle-based interactive freeform modeling of developable shapes.

DFT-NEGF Study of Electron Transfer Property in Graphene Nanoribbon Double Barrier System

Current-voltage (I – V) characteristics in armchair graphene nanoribbon (AGNR) double barrier systems (DBSs) are investigated by the density functional theory (DFT) and the non-equilibrium Green’s function (NEGF) methods. The hexagonal boron nitride (h-BN) which has an analogous structure with a graphene shows wide bandgap and becomes an electrical barrier in DBSs. The heterojunction structure of AGNR and two h-BNs with one six-membered ring width has properties as a resonant tunnelling device. Due to the resonance, sharp peaks are formed in the transmission function around the Fermi energy EF . Our previous studies have explained the origins of some peaks by solving the one-dimensional Dirac equation for massless particles. Here, by using the two-dimensional Dirac equation, we show that the remaining sharp peaks depend on the transverse nodal pattern of the wavefunction as well as the anisotropy of the Fermi velocity. Moreover, in the I – V characteristics, a flat part is formed without the negative differential resistance appearing. By partial density of state (PDOS) analysis, we reveal that the flat part in the current is caused by the fact that the peak positions in the resonance region are stable against the bias voltage.

空间维度形容词“THICK/THIN”的词汇类型学研究

Drawing on the theoretical framework and methodology of the Moscow Lexical Typology Group (MLexT), this paper examines the usage of the basic meanings of the spatial dimensional adjectives “THICK/THIN” in thirteen languages. Our conclusions are as follows: Among the thirteen languages investigated, the basic meanings of “THICK/THIN” in all Asian and European languages can indicate the distance between the upper and lower surfaces of a flat object, including “the upper and lower surfaces of a flat, solid object”, “the upper and lower surfaces of liquid”, “the irregular upper and lower surfaces of gas”, and “the upper and lower surfaces of a flat body part”. This reflects the cognitive commonality of different countries from different regions and cultures. For most Asian languages, “THICK/THIN” can only be used to describe the upper and lower surfaces of flat objects. For most European languages, “thick/thin” can describe flat as well as cylindrical and linear objects, which reflects cognitive characteristics of each country in different regions. Even within Asia, “THICK/THIN” are used in very different ways in Korean, Thai, Vietnamese, and Indonesian. In Korean, “THICK/THIN” can describe not only flat objects but also “linear objects on a flat surface”, while Vietnamese can describe not only flat objects but also “linear objects”, “linear objects on a flat surface”, and “cross-sections of cylindrical objects”. These two languages expand the semantic range of “THICK/THIN” in Asian languages. As with European languages, Indonesian and Thai use “thick/thin” for flat objects as well as cylindrical objects. However, “THICK/THIN” in Indonesian cannot describe the “cross-section of a cylindrical body part”. It is possible in Thai, but one cannot use “THICK/THIN” to describe the four limbs. Among European languages, French is an exception. “THICK/THIN” cannot describe a linear object placed in a three-dimensional space and not on a flat surface. We have thereby demonstrated cross-linguistic semantic commonalities and verified the feasibility and applicability of the MLexT theory in lexical typology. Meanwhile, the differences between different languages in different regions and in the same region also reveal the differences in the socio-cultural context of human cognition.

Effect of cold-form and tensile strain rate on mechanical properties of Q345 steel at elevated temperatures

In recent years, cold-formed steel has been extensively used, and the mechanical properties of cold-formed steel at elevated temperatures have been received considerable attention. However, little research on mechanical properties of the corner parts at elevated temperatures has been published. Meanwhile, the tensile strain rates adapted in the previous research on cold-formed steel are different, and the effect of this factor on mechanical properties was rarely investigated. In order to get a deeper understanding of the mechanical properties of cold-formed Q345 steel at elevated temperatures, an experimental investigation on flat and corner parts in cold-formed Q345 sections with two nominal thickness of 1.5 mm and 2.5 mm under three different tensile rates, 0.06/min, 0.6/min and 1.2/min, was carried out at elevated temperatures ranging from 20 °C to 800 °C. The effects of tension strain rate, cold-forming and thickness on mechanical properties of Q345 steel were systematically studied. Then the test results were compared with the prediction results provided by the current design standards and the other researchers. Furthermore, prediction equations were proposed to determine the mechanical properties of cold-formed Q345 steel.

Trapezoid-kinoform zone plate lens - a solution for efficient focusing in hard X-ray optics.

X-ray microscopes are powerful tools in the nano-inspection of materials owing to their ultra-high resolution at the molecular level. However, the focusing efficiency of binary zone plate lenses as key components in such probes is merely 5% in practice, hindering their application in advanced scientific research. Although kinoform zone plate lenses are in principle supposed to possess high efficiency beyond binary ones, little progress has been reported so far due to the shortage of both a theoretical calculation approach and greyscale lithography for generating fine three-dimensional (3D) kinoform zones of the lenses. This paper reports our theoretical work for a modified beam propagation method to compute the focusing performance and state-of-the-art 3D greyscale electron beam lithography for kinoform zone plate lenses. Three different zone shapes - binary, kinoform and top-flat kinoform (nicknamed the trapezoid-kinoform) - were compared both theoretically and experimentally. Theoretical calculations suggest, for the first time, that the trapezoid-kinoform zone plate gives rise to the highest focusing efficiency among the three lenses, which was proved by optical characterization of the fabricated lens with hard X-rays. As high as 40% of the focusing efficiency by Au trapezoid-kinoform lenses with resolution of 250 nm at 8 keV has been achieved, which is two times higher than that of binary zone plate lenses. The origin of the enhanced efficiency in the trapezoid-kinoform zone plate lens was explained by the joint contributions from both the refraction through the kinoform slope and the diffraction through the top flat part of the trapezoid-kinoform zone plate. Such a breakthrough in focusing efficiency sheds light on the further development of X-ray lenses with both high resolution and high efficiency.

Precipitation Behavior of O Phase during Continuous Cooling of Ti-22Al-25Nb Alloy

The microstructure evolution and formation mechanism of the O phase in a Ti-22Al-25Nb (at.%) orthorhombic alloy resulting from different cooling rates were investigated. The results show that the morphology of the precipitated O phase is significantly affected by the cooling rate. As the cooling rate decreases, the floccular O, composed of many fine acicular O phases, gradually grows into the lamellar O phase. When the alloy is cooled from the B2 phase region, the grain boundary O (OGB) preferentially nucleates at the triple junctions and grain boundaries and forms the flat and the zig-zag OGB according to different cooling rates. The OGB consists of separated, flat OGB parts and unconnected, zig-zag OGB composed of multiple short, separated, flat OGB at a higher cooling rate. The zig-zag OGB presents a connected state due to the sufficient diffusion time at a lower cooling rate. When the alloy is cooled from the (B2 + α2) phase region, the increase of the phase boundary provides favorable conditions for the nucleation of the O phase due to the presence of α2 particles. The precipitated rim O phase appears on the periphery of the α2 particles at lower cooling rates. The analysis indicates that the Widmanstätten intragranular O (OWI) precipitated directly from the B2 phase maintains the plane relation with the parent B2 phase, and the Widmanstätten grain boundary O (OWGB) holds the specific orientation relationship with one of the two adjacent B2 grains. The OGB keeps the specific orientation relationship with one of the B2 grains as much as possible. When it cannot maintain the specific orientation relationship with one of the B2 grains, the OGB maintains a near-orientation relationship with B2 grains on both sides to reduce the nucleation activation energy. Moreover, there can be more than one nucleation site for the O phase on a single B2 grain boundary to form the OGB. The rim O phase formed through a decomposition reaction of α2→α2 (Nb-lean) + O (Nb-rich) is controlled by a diffusional mechanism and maintains a specific orientation relationship, i.e., {001} O//{0001} α2 and <110>O//<112¯0> α2, with the parent α2 particles.

METHOD OF "SKELETAL STRUCTURES" TO SIMPLIFY THE PARAMETRIZATION PROCESS IN AUTOCAD

The article considers the method of "skeletal structures", proposed to simplify the process of parameterization. When parameterizing objects whose shape has more than one contour, there may be some complications, namely: auto-overlay dependencies, or sequential parameterization of the relative position of image fragments, can lead to an excessive number of dependencies, which can lead to inconsistencies when performing parameterization . The proposed method allows you to minimize such inconveniences, reduce the number of superimposed parameters and improve the quality of control over the shape of the object. The stages of parameterization of objects by the method of "skeletal structures" are formulated and characterized and recommendations for its use are given.
 The method of "skeletal structures" was developed and applied in the process of studying the topic "Parameterization" of the course "Engineering and Computer Graphics" at the Department of Descriptive Geometry, Engineering and Computer Graphics of the National Technical University of Ukraine "Kyiv Polytechnic Institute named after Igor Sikorsky". The application of the method on the example of flat parts of complex shape and for the structures used in the study of the topic "Assembly drawing" is demonstrated. As a condition of the task in the topic "Assembly drawing" we used a parameterized folding unit, which students adjusted to the parameters corresponding to the variant of the task, and supplemented the drawing with simplified images of fastening threaded elements made by them in the form of dynamic blocks.

SERS study of wheat leaves substrates with two different structures

Wheat leaf is a natural material having abundant gaps between micro-protrusions and flat structures. Magnetron sputtering method is used to sputter Ag film on wheat leaves and Rhodamine 6G (R6G) is used to detect the SERS difference caused by different structures of the same material. The SERS signal shows that the Raman intensity of the micro-protrusions is stronger than that of the flat parts. The results shows that there are more gaps in the protrusion structure per unit area, thereby providing more “hot spots”, which plays an important role in improving the SERS signal. Therefore, this low-cost and high-performance SERS system shows excellent application prospects and provides a new idea to improve SERS signal by using natural biomaterials as SERS substrate.

Дослідження величини пружної деформації деталей плоскоштанцювального преса, що перебувають у постійному контакті

Дослідження величини пружної деформації деталей плоскоштанцювального преса, що перебувають у постійному контакті

Синтаксономическое разнообразие лесных лугов Обь-Инского водораздела в пределах Новосибирской области

Синтаксономическое разнообразие лесных лугов Обь-Инского водораздела в пределах Новосибирской области

Особенности применения теоремы вириала для магнитных систем с квазибессиловыми обмотками

The article shows that in a magnetic system with a thin-walled balanced winding close to a force-free one, a significant increase in the parameter θ=WM γ/M σМ , is possible, which, according to the virial theorem, characterizes the ratio of the energy of the magnetic system WM to the weight of equipment with a material density γ, where under the action of electromagnetic forces there appears a mechanical stress σМ. In a quasi-force-free magnetic system, the main part of the winding is in a state of local equilibrium, and only a relatively small part of the equipment is subject to stress. This part determines the weight of the entire system, and this weight can be minimized. The configurations of balanced thin-walled windings are developed, at the boundaries two boundary conditions are fulfilled simultaneously - the absence of the induction component normal to the boundary and the constancy of the product of induction and radius. The authors consider an example of a system consisting of a main part - a sequence of balanced "transverse" modules in the form of flat discs and end parts, consisting of a combination of "transverse" modules and "longitudinal" ones, having the form of rings elongated along the axis with balanced end parts. It is shown that in the system under consideration, the characteristic dimensionless parameter θ with an unlimited increase in the number of elements of the main part can reach a value of about 24, and when the number of these elements changes within 20 - 40, it changes from 6 to 9.

Features of the application of the virial theorem for magnetic systems with quasi-force-free windings

The article shows that in a magnetic system with a thin-walled balanced winding close to a force-free one, a significant increase in the parameter theta=W_Mγ/MsigmaM, is possible, which, according to the virial theorem, characterizes the ratio of the energy of the magnetic system WM to the weight of equipment with a material density γ, where under the action of electromagnetic forces there appears a mechanical stress sigmaM. In a quasi-force-free magnetic system, the main part of the winding is in a state of local equilibrium, and only a relatively small part of the equipment is subject to stress. This part determines the weight of the entire system, and this weight can be minimized. The configurations of balanced thin-walled windings are developed, at the boundaries two boundary conditions are fulfilled simultaneously --- the absence of the induction component normal to the boundary and the constancy of the product of induction and radius. The authors consider an example of a system consisting of a main part - a sequence of balanced "transverse" modules in the form of flat discs and end parts, consisting of a combination of "transverse" modules and "longitudinal" ones, having the form of rings elongated along the axis with balanced end parts. It is shown that in the system under consideration, the characteristic dimensionless parameter theta with an unlimited increase in the number of elements of the main part can reach a value of about 24, and when the number of these elements changes within 20 -40, it changes from 6 to 9. Keywords: Quasi-force-free magnetic field, field energy, mass of a magnetic system, virial theorem, minimization of the ratio of mass to energy.