Combination Of Triangles Research Articles

Quadrilateral surface mesh generation with improved quality by combination of triangles

AbstractQuadrilateral mesh is preferred in numerical simulation compared with triangular mesh, but high‐quality and robust quadrilateral mesh generation for complex geometries remains a challenging problem. In this study, an enhanced indirect method by the combination of triangles is proposed for the generation of high‐quality quadrilateral mesh. It takes a triangular mesh as the input, and except that the number of elements needs to be even, the triangular mesh can be generated by the commonly used AFT method or Delaunay method. To ensure the quality of the combined quads, a local‐global triangular remeshing procedure is conducted first, and size gradation and vertex valence are focused in this step. Then, the well‐known Blossom algorithm is used to find the perfect matching triangles for combination. Finally, in order to reduce the number of unnecessary singularities, a connectivity optimization procedure is introduced to replace the irregular elements in local regions with regular elements and thus improve the overall quality of the combined quads. Numerical experiments on meshes in both 2D and 3D cases are presented to demonstrate the effectiveness of the proposed method.

Investigations on homothetic and hybrid micro-textured tools during turning Inconel-718

ABSTRACT Amused with the blissful benefits of micro-textures, researchers consider it a promising option for improving cutting tool performance, especially during machining superalloys. Through this study, the machining performance of two homothetic and six hybrid micro-textured tungsten carbide inserts have been comparatively assessed while dry turning Inconel-718. Dimple and channel micro-textures were the two independent homothetic textures. Dimple and channel micro-textures with 0°, 45°, and 90° orientation angles and a combination of triangle, square, and dimples constituted six different hybrid micro-textures. Micro-textures were fabricated on the rake face of inserts using a Ti-sapphire fired, nanosecond pulsed, infrared fiber laser. Dimple and channel micro-textured tools at 90° texture angle on rake face performed exceptionally well. Improvements in average tool life, cutting forces, and surface finish have been reported. Adhesion and attrition were the predominant forms of tool wear. Chip morphology study revealed long helical and continuous but segmented chips.

Investigating facemask problems associated with wearing comfort and fit

PurposeA facemask is used to cover the nose and mouth to protect a wearer's health in daily life. The authors’ long-term goal aimed to ensure more people with different physical characteristics and different attitudes can wear a high performance and comfortable facemask. In the present paper, wearers were surveyed by a questionnaire. Additionally, a prototype improvement pattern with a fit performance was investigated.Design/methodology/approachThe survey of facemask wearers was conducted with local students and international students in Japan. A basic pattern with high fit performance was analyzed using a combination of triangles based on the measured three-dimensional coordinates of the head shape of a Japanese mannequin.FindingsThe aggregated survey data indicated that 85.0% of the Japanese female students, 77.2% of international female students, 70.8% of Japanese male students and 54.3% of international male students were facemask wearers. Wearers had problems related to their masks' thermal, hygroscopic and airflow properties. Japanese nonusers did not wear them due to dislike related to the problems above. International nonusers had no experience of wearing them. It was concerned that these discomfort factors influence fit performance and reduction of wearing effects. Therefore, the authors analyzed a sheet pattern with a high fit performance for a Japanese head mannequin.Originality/valueThese results will contribute in improving hygienic facemasks for people at the global level. The survey results and pattern analysis provide of necessary conditions of development of the mask with comfortable and high fit performance.

Layered WS2 thin films prepared by sulfurization of sputtered W films

We present structural, optical and electrical investigations of layered WS2 films prepared on tungsten. A two-step technique has been used to synthesize layered WS2 films using sulfurization of W films sputtered with thinner (1 and 2 nm) and thicker (14 and 28 nm) thicknesses at 800 °C. XRD analysis revealed that the examined films are polycrystalline with texture and have a 2H-WS2 hexagonal microstructure. Using Raman spectroscopy with the 532 nm laser excitation, the presence of E12g and A1g vibration modes was observed and the layered nature of WS2 was confirmed. FE SEM observations showed two different surface morphologies. The samples grown on thinner W films were not compact over the surface and agglomeration of nanosize grains in combination of triangles and flakes was visible. In another group the surface was lamellar and contained plenty of nanorods embedded vertically and/or inclined at different angles to the surface. Layered WS2 films exhibited a direct band gap in the range of 2.1–2.5 eV and they were n-type semiconductors with the sheet resistance in the order of several MΩ at room temperature.

Model-basedcardiacdoseestimation in radiationtreatment of leftbreastcancer.

To develop a mathematical model for cardiac dose estimation for patients who have been treated for left-sided breast cancer without CT data. After obtaining institutionalreview board approvals, 147 patients with left-sided breast cancer were selected that were treated supine with opposed tangents. The heart blocks from the tangential fields were removed and dose calculations were performed with 6 MV beams using an advanced algorithm. This study was performed with CT data with DRR to represent a radiographic simulator image of yesteryear treatments. The beam'seye-view images showing delineated breast, lung and heart were created to represent views on radiograph. The maximum heart distance (MHD) was recorded and irradiated heart area (AREA) was computed by combination of triangles and rectangles. Based on accurate 3D dose calculation, mean dose (Dmean) and V10 to V50 of heart were analyzed with respect to MHD and AREA for dosimetric parameters using linear and quadratic fit. The treatment parameters calculated by MHD and segments using 2D radiographs were within 2% of the actual dosimetric parameters computed from the 3D planning system. The MHD and AREA vs Dmean, V10, V20, V30 and V50 showed very good correlation with linear model (R2 >0.91); however the correlation was significantly better with quadratic model (R2 >0.92). The analysis of the dosimetric error with our linear and quadratic model is remarkable within <3% error for most cases. The proposed mathematical model for the cardiac dose estimation is accurate within ±3% using a radiograph without CT data. This provides avenues for patient pooling in future studies related to radiation dose and cardiac toxicity. These results will help in estimating cardiac dose analysis accurately from previous studies as well as in centers still using 2D planning. The evidence of cardiac risk following radiotherapy continues to be one of the important considerations for the management of left-sided breast cancer patients. One of the problem in the estimation of dose-risk effects is the reconstruction of heart dose for pre-CT treatments. In this study, a simple mathematical model is presented that could estimate cardiac dose within ±3% in left breast cancer treatment from 2D radiograph where CT data do not exist.

Simulation of Nine-point Circle Using Novel Computing Tools and Investigating the Associated Useful Properties

The point, line, triangle and circle are the first set of figures in the world of geometry. The geometries of lines, triangles and circles have been studied and analyzed to obtain some specific and useful results for a long period of time. The analysis and determining various facts in the form of theorems and findings have been carried out by innumerable learned scholars and researchers using the basic tools, logical agreement and testing the data about these figures. The combination of triangle and circle in form of circumscribing circle and in-circle has also been studied at depth. The third fabulous circle is popularly known as the nine-point circle or Feuerbach's circle or Euler circle. The nine-point circle brings in light many interesting and useful properties of the basic triangle. But the construction of the nine-point circle is little tedious and cumbersome. This is because of the facts associated with the nine point circle. Therefore; in this paper the authors have developed a dedicated program in the world famous software MATLAB®. It is attempted to create a large number of triangle data and use them for verifying the useful results in addition to the construction of nine point circle.

Coupled segmentation and similarity detection for architectural models

Recent shape retrieval and interactive modeling algorithms enable the re-use of existing models in many applications. However, most of those techniques require a pre-labeled model with some semantic information. We introduce a fully automatic approach to simultaneously segment and detect similarities within an existing 3D architectural model. Our framework approaches the segmentation problem as a weighted minimum set cover over an input triangle soup, and maximizes the repetition of similar segments to find a best set of unique component types and instances. The solution for this set-cover formulation starts with a search space reduction to eliminate unlikely combinations of triangles, and continues with a combinatorial optimization within each disjoint subspace that outputs the components and their types. We show the discovered components of a variety of architectural models obtained from public databases. We demonstrate experiments testing the robustness of our algorithm, in terms of threshold sensitivity, vertex displacement, and triangulation variations of the original model. In addition, we compare our components with those of competing approaches and evaluate our results against user-based segmentations. We have processed a database of 50 buildings, with various structures and over 200K polygons per building, with a segmentation time averaging up to 4 minutes.

The optimal structure of two dimensional photonic crystals with the large absolute band gap

This paper reports a new designed square lattice GaAs structure of two-dimensional photonic crystals with absolute band gap approach to 0.1623 (2πc/a), where a is the period of the square lattice. The optimal structure is obtained by combining the Geometry Projection Method and Finite Element Method. Both gradient information and symmetric control points are introduced to reduce the calculation cost. For benefit to the fabrication in reality, the structure is simplified by the combination of triangle and rectangular geometry. Through parameter optimization, the absolute band gap of the new structure is improved to 0.1735 (2πc/a), which is much larger than those reported before. The new PC structure is convenient and stab for fabrication, and may be found applications in the future optical devices.

Construction of the Dirichlet to Neumann Boundary Operator for Triangles and Applications in the Analysis of Polygonal Conductors

This paper introduces a fast and accurate method to investigate the broadband inductive and resistive behavior of conductors with a nonrectangular cross section. The presented iterative combined waveguide mode (ICWM) algorithm leads to an expansion of the longitudinal electric field inside a triangle using a combination of parallel-plate waveguide modes in three directions, each perpendicular to one of the triangle sides. This expansion is used to calculate the triangle's Dirichlet to Neumann boundary operator. Subsequently, any polygonal conductor can be modeled as a combination of triangles. The method is especially useful to investigate current crowding effects near sharp conductor corners. In a number of numerical examples, the accuracy of the ICWM algorithm is investigated, and the method is applied to some polygonal conductor configurations.

Truss topology optimization by a modified genetic algorithm

This paper describes the use of a stochastic search procedure based on genetic algorithms for developing near-optimal topologies of load-bearing truss structures. Most existing cases these publications express the truss topology as a combination of members. These methods, however, have the disadvantage that the resulting topology may include needless members or those which overlap other members. In addition to these problems, the generated structures are not necessarily structurally stable. A new method, which resolves these problems by expressing the truss topology as a combination of triangles, is proposed in this paper. Details of the proposed methodology are presented as well as the results of numerical examples that clearly show the effectiveness and efficiency of the method.

遺伝的アルゴリズムによる立体トラス構造物の形態創生

Present paper describes the use of a stochastic search procedure that is the bases of genetic algorithms (GAs), in developing near-optimal topologies of load-bearing truss structures. Many works have been already published until today on the structural optimization of truss topology using the genetic algorithms. In most cases these works express the truss topology as a combination of members, and existence of each member is directly connected to the genetic code. These methods, however, have a fatal weak point. Namely when the topology is made along these methods, they might include needless members or those which lies on the other members. In addition to these problems, generated structures are not always stable. These problems become more remarkable when the freedom of the problem becomes large. We have already proposed a new method that resolves those problems by expressing the truss topology as a combination of triangles that are joined with each other. However, the length of chromosome tended to become long. This paper proposes brand-new implements for effective optimization. Detail of the proposed methodology is presented as well as the results of numerical examples that clearly show effectiveness and efficiency of the present method.

遺伝的アルゴリズムを用いたトラス構造物の形態創出

Many works have been already published until today on the structural optimization of truss topology using the genetic algorithms. In most cases these works express the truss topology as a combination of members, and existence of each member is directly connected to the genetic code. These methods, however, have a fatal weak point. Namely when the topology is made along these methods, they might include needless members or those which lies on the other members. In addition to these problems, generated structures are not always given as a stable structure. These problems become more remarkable when the freedom of the problem becomes large. A new method is proposed in the present paper resolving those problems by expressing the truss topology as a combination of triangles which are joined each other. Detail of the proposed methodology is pre sented as well as the results of numerical examples which clearly show effectiveness and efficiency of the present method.