Modeling Of Curved Surfaces Research Articles

Reconstruction method of high-precision longwall mining floor curved surface model driven by data points fitting of equipment

Abstract High-precision coal seam model is the basis of intelligent mining. The longwall mining face floor model, which can provide data sources for the correction of the dynamic coal seam model, is difficult to measurement directly. To address this issue, this paper proposes a high-precision coal seam surface model reconstruction and correction method based on a large number of operating data points. Firstly, the coupling model of equipment and floor is obtained based on the coupling model of plane and surface. Subsequently, the plane data points of the equipment are corrected based on the coupling model of equipment and floor to obtain the floor reconstruction points. The Catmull–Clark surface subdivision method is then used to subdivide the plane formed by the equipment data points to obtain surface subdivision points. The floor model reconstructed using surface data points is validated and corrected using the physics engine in the Unity 3d platform. Finally, the verification of the reconstruction point selection method, the coupling principle between the equipment and the floor model, the reconstruction accuracy of the base plate and the correction principle were carried out based on the equipment and floor model in the laboratory. The experimental results show the feasibility of the floor reconstruction, verification and correction method, which can provide a new idea for the reconstruction of the floor of the longwall mining face and the correction of the dynamic coal seam.

Fabrication of electrical devices on conformal surfaces based on array nozzle and five-axis motion mechanism

It has been known that conformal printing with a single nozzle has low efficiency. This study proposes a novel non-expandable curved surface printing method that could realize high-efficiency printing with array nozzles. First, based on the non-uniform rational B-splines curved surface reconstruction method, the parameter equation of the stereolithography format curved surface model is obtained. An equidistant parallel curve filling method is proposed based on the parameter equation. According to the filling accuracy, a spatial equidistant curve network model is established by fitting the surface. Using each node on the curve network as the filling pixel increases the filling rate of the non-expandable surface and improves the printing accuracy. Compared with that of the traditional equidistant filling, the droplet filling rate could be increased by 13.05 % in this study. Finally, based on the self-developed five-axis curved surface inkjet printing system and normal vector printing method, samples of concave, convex, and multi-material conformal surfaces are sequentially printed. Our research finding lays the foundation for high-efficiency integrated molding of electronic devices with complex conformal surfaces.

Surface Topography Prediction Model for Free-form Surface Milling under a Dynamic System Response

At present, numerous studies on surface topography prediction models for plane workpieces have been performed at home and abroad. Given the complexity of curved surface models (especially free-form surfaces that cannot be expressed in analytic formulas), prediction models for the surface topography of free-form surfaces are rarely studied. This paper aims to establish and simulate a 3D surface topography model of ball-end milling for all types of curved surfaces, including simple surfaces and free-form surfaces. The dynamic factors influencing the surface topography, such as the spindle runout initial phase angle, runout amplitude, axial drift initial phase angle, and axial drift amplitude are considered in this model. Moreover, some processing parameters influencing the surface topography, such as cutter tooth number, machining inclination, radial cutting depth, feeding frequency and feed per tooth are also considered in this model. The simulation results can be used to optimize the milling process of the actual free-form surface to improve workpiece surface quality or to predict the surface topography of the given machining parameters.

Constructing Artistic Surface Modeling Design Based on Nonlinear Over-limit Interpolation Equation

Abstract The digital and physical methods of establishing minimal curved surfaces are the basis for realizing the design of the minimal curved surface modeling structure. Based on this research background, the paper showed an artistic surface modeling method based on nonlinear over-limit difference equations. The article combines parameter optimization and 3D modeling methods to model the constructed surface modeling. The research found that the nonlinear out-of-limit difference equation proposed in the paper is more accurate than the standard fractional differential equation algorithm. For this reason, the method can be extended and applied to the design of artistic surface modeling.

Defects in Hard Carbon: Where Are They Located and How Does the Location Affect Alkaline Metal Storage?

Hard carbon anodes have shown significant promise for next-generation battery technologies. These nanoporous carbon materials are highly complex and vary in structure depending on synthesis method, precursors, and pyrolysis temperature. Structurally, hard carbons are shown to consist of disordered planar and curved motifs, which have a dramatic impact on anode performance. Here, the impact of position on defect formation energy is explored through density functional theory simulations, employing a mixed planar bulk and curved surface model. At defect sites close to the surface, a dramatic decrease ( 50%) in defect formation energy is observed for all defects except the nitrogen substitutional defect. These results confirm the experimentally observed enhanced defect concentration at surfaces. Previous studies have shown that defects have a marked impact on metal storage. This work explores the interplay between position and defect type for lithium, sodium, and potassium adsorption. Regardless of defect location, it is found that the energetic contributions to the metal adsorption energies are principally dictated by the defect type and carbon interlayer distance.

Intelligent vehicle modeling design based on image processing

With the urgent demand of consumers for diversified automobile modeling, simple, efficient, and intelligent automobile modeling analysis and modeling method is an urgent problem to be solved in current automobile modeling design. The purpose of this article is to analyze the modeling preference and trend of the current automobile market in time, which can assist the modeling design of new models of automobile main engine factories and strengthen their branding family. Intelligent rapid modeling shortens the current modeling design cycle, so that the product rapid iteration is to occupy an active position in the automotive market. In this article, aiming at the family analysis of automobile front face, the image database of automobile front face modeling analysis was created. The database included two data sets of vehicle signs and no vehicle signs, and the image data of vehicle front face modeling of most models of 22 domestic mainstream brands were collected. Then, this article adopts the image classification processing method in computer vision to conduct car brand classification training on the database. Based on ResNet-8 and other model architectures, it trains and classifies the intelligent vehicle brand classification database with and without vehicle label. Finally, based on the shape coefficient, a 3D wireframe model and a curved surface model are obtained. The experimental results show that the 3D curve model can be obtained based on a single image from any angle, which greatly shortens the modeling period by 92%.

Research on TIN Curved Surface Modeling Technology and Its Application in Foundation Pit Monitoring

In order to Study the Foundation Pit Surface Deformation Amount and its Three-Dimensional Visualization, The Surface Modeling Technique Based on the Grid-Type Discrete Point Cloud Data and Tin Data Model is proposed. Indoor Tests Show that the Minimum Value of the Maximum Residual Value of this Technology is 0.5612~0.9993, Which Meets the Requirements of the Software Spatial Coordinate Solution and Three-Dimensional Reconstruction. And Monitoring the Application Test, the Actual Value and Calculation Value Error is Less Than 1mm, Accuracy and Error Meet the Requirements of the Engineering Measurement Specifications. Finally, the Feasibility of the Technology is Verified by the Field Test.

Improved Double-Arctan Transformation for the Stable Evaluation of Nearly Hypersingular Integrals in SIE

The evaluation of singular or near-singular integrals is one of the key techniques in the integral equation method. Based on the previously proposed double-arctan transformation (DAT) for the nearly hypersingular integrals in curved surface modeling, this work presents new transformation methods to improve the accuracy and stability of DAT for the following two situations, i.e., the field point is: 1) extremely close to the source surface and 2) extremely close to the boundary of the source surface. The original DAT fails in these two situations and, hence, limits its applications. The reasons that cause such an instability are studied. Two additional transformations are introduced to make the DAT stable for these two cases. For situation I, the exponential transformation (ET) is adopted to optimize the distribution of the Gaussian quadrature points. For situation II, the shape-function transformation (SFT) is further proposed to remove the nearly angular singularity . We denote the newly developed DAT with ET and SFT as the improved DAT (IDAT) in this communication. The typical testing cases are provided to validate the proposed method.

Effects of tool orientation and surface curvature on surface integrity in ball end milling of TC17

Tool orientation has an important effect on the surface quality of a free-form surface during ball end milling process, and the selection of tool orientation is important to ensure the surface quality. In this work, a series of milling experiments were performed by using a carbide ball end mill on a workpiece of TC17 titanium alloy. The purpose of this study was to determine the tool orientation producing optimal surface integrity. The results showed that the surface roughness in both directions was better when the rotational angle was within the range of 0°~90° and with a constant inclination angle. In addition, inclination angle had little effect on the roughness in the feed direction, whereas a much larger or smaller angle led to greater roughness in the step direction. The tool orientation strongly affected the surface morphology. Compressive residual stress was detected on all machined surfaces. The maximum surface residual stress was obtained when the rotational angle was 90°, and the surface residual stress decreased as the inclination angle increased. On this basis, four curved surface models with different curvatures were established according to the features of a blade, and the effects of inclination angle and cutter path orientation on surface integrity were studied. The results indicated that the surface roughness produced with an upward orientation varied more than that produced with a downward orientation for a steep curved surface; the value of the roughness was small for a horizontal orientation and when the machine surface was very smooth. The machined surface for a flat curved surface was smoother, and there were no obvious differences in surface morphology between the two cutter path orientations. For steep curved surfaces, the cutter path orientation had no obvious influence on the residual stress, and a greater value was obtained when the surface was much steeper. For flat curved surfaces, the residual stress had no obvious variation resulting from small changes of the inclination angle.

腹部X線CT画像からの脊柱, 肋骨, 椎間板, 脊椎の段階的認識

This paper proposes a structure-by-structure recognition method of spinal columns, ribs, intervertebral disks and vertebrae in abdominal X-ray CT images. First, bone regions are extracted by applying binarization operators to CT images, and then spinal columns and ribs are extracted from the bone regions by using morphological operators. Intervertebral disks are emphasized, and then plane models are fitted to the intervertebral disks to recognize their positions and directions. The spinal columns are divided into vertebrae based on the plane models. Spinal processes have more irregular shapes. In order to recognize vertebrae including the spinal processes, the plane models are converted into curved surface models that are represented by control points. The curved surface models are transformed by minimizing an energy function to evaluate (1) the smoothness of the curved surface models and (2) the fidelity of the model to pixel-value distributions in the images. By using the plane and curved surface models, thoracic and lumbar vertebrae are recognized. The proposed method was applied to fifteen cases and was able to correctly recognize 95% of ribs, 100% of intervertebral disks, and 75% of vertebrae. The experimental results demonstrated that the proposed method was promising as a means of recognizing bone regions in abdominal X-ray CT images.

Research and Modeling of Blades with Complex Surfaces Based on Laser Rapid Prototyping

Usually, generating parts with complex surfaces, especially three-dimensional (3D) curved-surface blades, involves difficult designing, complicated manufacturing processes, and low production efficiency. In this study, by integrating 3D curved-surface modeling and the rapid prototyping functions of the pro/E software platform with computer-aided design, layered manufacturing, and material curing technologies, an improved process was realized. The once-challenging fabrication of irregular curved-surface blades was transformed into a simple technique of making planes. By selectively curing the raw material, as demonstrated in this study, complex surfaces can be manufactured rapidly, thus shortening research and development stages of new products, reducing costs, and endowing manufacturers with an improved capacity to research and develop products with greater competence and accuracy .

Quick segmentation for complex curved surface with local geometric feature based on IGES and Open CASCADE

Complex curved surface parts with local geometric feature are usually critical parts in high-end equipments. However, the processing for this kind of parts is usually difficult or inefficient due to the adoption of difficult-to-machine material and special structure. Current approaches cannot satisfy the rapid development of high-end equipments. Due to the existence of the local geometric feature for the parts, processing such parts with constant machining parameters is less applicative, restricting the improvement of machining efficiency. By separating the local geometric feature and generating tool path for the local geometric feature and the remaining processing area separately, the more efficient machining with variable machining parameters will be obtained for the complex curved surface with local geometric feature. In this way, the quick segmentation for the complex curved surface with local geometric feature is of great importance to the NC machining with variable machining parameters for this kind of parts, and a quick segmentation system is developed based on Initial Graphics Exchange Specification (IGES) and Open CASCADE (OCC) platform in this study. The complex curved surface model in IGES format is firstly imported into the system and then trimmed into independent surface patches. After computing the feature size of each surface patch, the segmentation for the complex curved surface is achieved by sorting and classifying the surface patches according to their feature sizes. Taking the whole impeller with small splitter blades for an example, the experimental result shows that the segmentation of small splitter blades from the whole impeller is successful and a serialized processing program could be generated, and then the whole impeller could be machined precisely and efficiently with NC equipment. In the machining experiment, it is proved that the machining with various machining parameters can improve the efficiency by 28.18% in the comparison experiment, 20.14% and 12.33% in the estimation. The research provides an important foundation for the high quality and more efficient machining of the complex curved surface with local geometric feature.

The Use of NURBS Modeling in the Ceramic Design

NURBS is a great modeling method which is supported in all the advanced three-dimensional softwares. With NURBS, people can create the lively and vivid models on the computer. And it plays a role on the model designing of chinas.combining with the experience of practices, the dissertation will analyze with cases to curved surface model of the china’s style designs and mainly study NURBS curved surface modeling taking the method of ceramic design.

A new thermal conductivity estimation model for weathered granite soils in Korea

Thermal conductivity of ground has a great influence on the performance of Ground Heat Exchangers (GHEs). In general, the ground thermal conductivity significantly depends on the density (or porosity) and the moisture content since they are decisive factors that determine the interface area between soil particles which is available for heat transfer. In this study, a large number of thermal conductivity experiments were conducted for soils of varying porosity and moisture content, and a database of thermal properties for the weathered granite soils was set up. Based on the database, a 3D Curved Surface Model and an Artificial Neural Network Model (ANNM) were proposed for estimating the thermal conductivity. The new models were validated by comparing predictions by the models with new thermal conductivity data, which had not been used in developing the models. As for the 3D CSM, the normalized average values of training and test data were 1.079 and 1.061 with variations of 0.158 and 0.148, respectively. The predictions became somewhat unreliable in a low range of thermal conductivity values in considering the distribution pattern. As for the ANNM, the 'Logsig-Tansig' transfer function combination with nine neurons gave the most accurate estimates. The normalized average values of training data and test data were 1.006 and 0.954 with variations of 0.026 and 0.098, respectively. It can be concluded that the ANNM gives much better results than the 3D CSM.

Modeling the Soil Water Retention Curves of Soil-Gravel Mixtures with Regression Method on the Loess Plateau of China

Soil water retention parameters are critical to quantify flow and solute transport in vadose zone, while the presence of rock fragments remarkably increases their variability. Therefore a novel method for determining water retention parameters of soil-gravel mixtures is required. The procedure to generate such a model is based firstly on the determination of the quantitative relationship between the content of rock fragments and the effective saturation of soil-gravel mixtures, and then on the integration of this relationship with former analytical equations of water retention curves (WRCs). In order to find such relationships, laboratory experiments were conducted to determine WRCs of soil-gravel mixtures obtained with a clay loam soil mixed with shale clasts or pebbles in three size groups with various gravel contents. Data showed that the effective saturation of the soil-gravel mixtures with the same kind of gravels within one size group had a linear relation with gravel contents, and had a power relation with the bulk density of samples at any pressure head. Revised formulas for water retention properties of the soil-gravel mixtures are proposed to establish the water retention curved surface models of the power-linear functions and power functions. The analysis of the parameters obtained by regression and validation of the empirical models showed that they were acceptable by using either the measured data of separate gravel size group or those of all the three gravel size groups having a large size range. Furthermore, the regression parameters of the curved surfaces for the soil-gravel mixtures with a large range of gravel content could be determined from the water retention data of the soil-gravel mixtures with two representative gravel contents or bulk densities. Such revised water retention models are potentially applicable in regional or large scale field investigations of significantly heterogeneous media, where various gravel sizes and different gravel contents are present.

Study on the Online Ink Testing with CCD Based on Calabro-Mercatucci Model

With the increasing of press’ speed and the people’s requirement, online testing of printed stock becomes to the development direction. The ink metering control is an important part of printing quality control. So this paper sets up a three-dimensional curved surface model of the CCD’s RGB values and the best ink film thicknesses based on Calabro-Mercatucci model, which can be applied to the online ink testing with CCD. Firstly, we printed cyan magenta yellow black color bitches of different ink film thicknesses and got their optical densities and RGB values with measuring tools. Afterwards, we got the parameters in Calabro-Mercatucci model with the experimental data through the least square algorithm and then got the scale of the best ink film thickness. Last, we set up the three-dimensional curved surface model of the CCD’s RGB values and the best ink film thicknesses through ‘v4’ algorithm in matlab tools. With this three-dimensional curved surface model, we can judge whether the thickness corresponding to the RGB values is in the range of the best ink film thickness. It is proved that this method can indicate the relationship between CCD’s RGB values and the ink film thickness and be applied to detect the ink metering after tested.

Simplified parasitic capacitance extraction of shield in HVDC converter system with boundary element method

It is critical to build a wide-band circuit model to conduct research on the characteristics of the electromagnetic disturbance source during the localization of high voltage direct current (HVDC) technology. Parasitic capacitance is most essential for modeling the equivalent circuit, so a fast and accurate computation of capacitance parameters plays a vital role. Because of the large size and complex structure of the converter equipment, it is impossible to obtain capacitance parameters by means of measurement or simulating calculation with finite element software. In this paper, a simplified method of capacitance extraction based on boundary element method is proposed, which can provide an efficient means of establishing simulation models. In the method presented, simulation model of the shield may not be chamfered. Consequently, the edge and corner of the shield do not need to be handled with a sphere, cylinder and other curved surface model. The availability of this method is demonstrated by comparing the capacitance parameters of chamfered shield with that of non-chamfered shield.

Theoretical demonstration of symmetric [formula omitted] curves in asymmetric molecular junction of monothiolate alkane

A molecular junction of an asymmetric molecule generally demonstrates an asymmetric current–voltage (I–V) curve, due to the unequal voltage drops at the two molecule–electrode contacts. However, for asymmetric S(CH2)nCH3 molecules, symmetric I–V curves are always obtained in the experimental measurements. Here, we investigate the electronic transport of the Au–S(CH2)7CH3–Au molecular junction in order to reveal the mechanism of the symmetric I–V curve with ATK package, in which the density functional theory is combined with Keldysh nonequilibrium Green's function method to calculate the electronic and transport properties of nanoscale systems. And the symmetric I–V curve can be interpreted by the curved surface model, which reproduces curved surface of the top electrode in the experiment.

A Novel Expression of Spatial Correlation by a Random Curved Surface Model and Its Application to LSI Design

We have proposed a random curved surface model as a new mathematical concept which enables the expression of spatial correlation. The model gives us an appropriate methodology to deal with the systematic components of device variation in an LSI chip. The key idea of the model is the fitting of a polynomial to an array of Gaussian random numbers. The curved surface is expressed by a new extension from the Legendre polynomials to form two-dimensional formulas. The formulas were proven to be suitable to express the spatial correlation with reasonable computational complexity. In this paper, we show that this approach is useful in analyzing characteristics of device variation of actual chips by using experimental data.

3D 동체 모형을 이용한 2D 전개 패턴 연구

To understand the basic relationship between 3D curved surface model and 2D pattern, simplified torso model was generated by commercial CAD program (IDEAS). 3D torso model was then divided into different blocks and unfolded into a flat pattern as in ordinary works of clothing item design. As results, 2D pattern development of different part of 3D torso model was attempted and analyzed mathematically. It was found that different height, radius and tangent slope of 3D blocks resulted in different 2D pattern. The relationships between the shape parameters of 3D torso blocks and those of 2D patterns were analyzed using regression equations. Direct way of drawing a 2D pattern of corresponding 3D torso block was also illustrated for the convenience of pattern making using conventional measurements of upper/ lower radii and height of 3D torso block.