plane boundary
Recently Published Documents


TOTAL DOCUMENTS

450
(FIVE YEARS 39)

H-INDEX

37
(FIVE YEARS 1)

2021 ◽  
Vol 14 (1) ◽  
pp. 95
Author(s):  
Zhonghua Su ◽  
Zhenji Gao ◽  
Guiyun Zhou ◽  
Shihua Li ◽  
Lihui Song ◽  
...  

Planes are essential features to describe the shapes of buildings. The segmentation of a plane is significant when reconstructing a building in three dimensions. However, there is a concern about the accuracy in segmenting plane from point cloud data. The objective of this paper was to develop an effective segmentation algorithm for building planes that combines the region growing algorithm with the distance algorithm based on boundary points. The method was tested on point cloud data from a cottage and pantry as scanned using a Faro Focus 3D laser range scanner and Matterport Camera, respectively. A coarse extraction of the building plane was obtained from the region growing algorithm. The coplanar points where two planes intersect were obtained from the distance algorithm. The building plane’s optimal segmentation was then obtained by combining the coarse extraction plane points and the corresponding coplanar points. The results show that the proposed method successfully segmented the plane points of the cottage and pantry. The optimal distance thresholds using the proposed method from the uncoarse extraction plane points to each plane boundary point of cottage and pantry were 0.025 m and 0.030 m, respectively. The highest correct rate and the highest error rate of the cottage’s (pantry’s) plane segmentations using the proposed method under the optimal distance threshold were 99.93% and 2.30% (98.55% and 2.44%), respectively. The F1 score value of the cottage’s and pantry’s plane segmentations using the proposed method under the optimal distance threshold reached 97.56% and 95.75%, respectively. This method can segment different objects on the same plane, while the random sample consensus (RANSAC) algorithm causes the plane to become over-segmented. The proposed method can also extract the coplanar points at the intersection of two planes, which cannot be separated using the region growing algorithm. Although the RANSAC-RG method combining the RANSAC algorithm and the region growing algorithm can optimize the segmentation results of the RANSAC (region growing) algorithm and has little difference in segmentation effect (especially for cottage data) with the proposed method, the method still loses coplanar points at some intersection of the two planes.


Author(s):  
Zhiming Huang ◽  
Zhenbang Rong ◽  
Yiyong Ye

We study the quantum teleportation under fluctuating electromagnetic field in the presence of a perfectly reflecting boundary. The noisy scheme of quantum teleportation affected by electromagnetic fluctuation is proposed. Then we calculate and investigate the behaviors of entanglement and fidelity, which are closely related to the plane boundary and atomic polarization. After a period of evolution, entanglement and fidelity evolve to zero and nonzero stable value respectively. Fidelity is closely related to the weight parameter and phase parameter of the teleported state. Besides, small two-atom separation makes entanglement and fidelity have better enhancement. Furthermore, the presence of boundary, atomic polarization and two-atom separation offers us more freedom to adjust the performance of the quantum teleportation. The results would give us new insight into quantum communication in an open quantum system since quantum teleportation plays an important role in quantum communication and quantum information.


2021 ◽  
Author(s):  
Rong TU ◽  
Ziming LIU ◽  
Chongjie WANG ◽  
Pengjian LU ◽  
Bingjian GUO ◽  
...  

Abstract The use of hafnia (HfO2) has facilitated recent advances in combining uprated dielectric layers (UDLs) and environmental barriers (EBs) in supercomputers. However, an extremely low deposition rate limits further development and fabrication efficiency of HfO2 films. In this study, high-throughput growth of HfO2 films was realized via laser chemical vapor deposition using a laser spot with a gradient temperature distribution. In HfO2 films fabricated by a single growth process, four regions with different morphologies could be discerned for deposition temperatures increasing from 1300 K to 1600 K: leaf-like, pyramid-like, bromeliad-like and pinecone-like. Two growth modes were observed for Regions I and II: Stranski-Krastanov and Volmer-Weber. Regions III and IV contained coexisting monoclinic and tetragonal HfO2 grains with an in-plane boundary for m-HfO2 (-110) {111}//t-HfO2 (1-11) {111}. The maximum deposition rate reached 362 μm/h, which was 102 - 104 times higher than that obtained using existing deposition methods.


Nano Research ◽  
2021 ◽  
Author(s):  
Shuna Li ◽  
Yao Wang ◽  
Yunrui Li ◽  
Xu Fang ◽  
Yujie Liu ◽  
...  

Author(s):  
Hoang Van Tung ◽  
Pham Thanh Hieu

This paper presents an analytical approach to investigate the buckling of sandwich cylindrical shells subjected to uniform temperature rise and external lateral pressure. Two sandwich models corresponding to carbon nanotube reinforced composite (CNTRC) face sheets and core layer are considered. The properties of all constitutive materials are assumed to be temperature dependent and effective properties of CNTRC are determined according to an extended rule of mixture. Governing equations are established using first order shear deformation theory and solved employing two-term form of deflection along with Galerkin method for simply supported edge shells. In order to account for practical situations of in-plane boundary condition, the elasticity of tangential constraint of boundary edges is included. Owing to temperature dependence of material properties, critical thermal loads are determined adopting an iteration process. Numerous parametric studies are carried out and interesting remarks are given. The study reveals that sandwich shell model with CNTRC core layer and homogeneous skins has considerably strong capacity of buckling resistance. Numerical results also indicate that tangential edge constraint has significant effects on critical loads, especially at elevated temperature. In addition, in the case of thermal load, an intermediate volume percentage of carbon nanotubes can confer the highest critical temperatures of sandwich shells.


2021 ◽  
Vol 33 (9) ◽  
pp. 097106
Author(s):  
Samayam Satish ◽  
Justin S. Leontini ◽  
Richard Manasseh ◽  
S. A. Sannasiraj ◽  
V. Sundar

2021 ◽  
Vol 3 (9) ◽  
Author(s):  
Mehdi Panji ◽  
Saeed Mojtabazadeh-Hasanlouei

Abstract In this paper, the geometrical effects of shallow twin lined tunnels with different cross sections are investigated to obtain the anti-plane seismic ground motion under vertical/horizontal incident plane SH waves. A model of long two-dimensional lined tunnels is established and embedded in a homogeneous linear elastic half-plane by an applied numerical time-domain boundary element approach. In addition to a brief introduction to the formulation of the method, by considering five tunnel sections including circular, elliptical, horseshoe, square and rectangular, the surface response is sensitized to observe the normalized displacement amplitude/amplification ratio. In this regard, the angle of the incident wave and the frequency of the response are also included in changing the response pattern. To illustrate the results in both time and frequency domains, they are presented as blanket charts, snapshots, and three-/two-dimensional diagrams. The results showed that the seismic response of the surface is extremely affected by the geometric parameters of underground tunnels, which can create different conditions on the ground surface with shifting the direction of the wavefront. Article Highlights Geometrical effect of twin horizontally overlapping lined tunnels. Applying a time-domain half-plane boundary element method. Illustrating the response in time and frequency domains. The effect of depth and distance ratios on the seismic ground motion. Propagating vertical and horizontal incident SH-wave type. Graphic Abstract


Author(s):  
Yanguang Long ◽  
Jinjun Wang ◽  
Chong Pan

The sharp but irregular interface that separates the instantaneous turbulent and irrotational flows is termed as the turbulent/non-turbulent interface (TNTI). TNTI can be widely observed in various types of flow, such as turbulent boundary layers, jets and combustion flame fronts. Due to its importance on the intermittency and entrainment process, TNTI has been widely explored in its geometry and dynamic properties (da Silva et al., 2014). Most of the studies focus on the TNTIs in smooth plane boundary layer, while few investigate the effects of wall shapes. However, the wall conditions in many engineering applications are complex and heterogeneous, which will induce large-scale heterogeneity (Barros and Christensen, 2014) and require further investigations. To shed new light on the intermittency and entrainment above complex surfaces, the TNTI over spanwise heterogeneity are investigated here with time-resolved stereoscopic PIV (TR-SPIV). The model and TR-SPIV experimental set-up are shown in Fig. 1. The experiments are conducted in the low-speed water channel at Beijing University of Aeronautics and Astronautics. The spanwise distance S between two adjacent ridges is S/(δ) = 1.35, where (δ) is the spanwise-averaged boundary layer thickness. This spanwise distance is selected to induced strong secondary vortices (Vanderwel and Ganapathisubramani, 2015; Wangsawijaya et al., 2020). The Reynolds number based on the streamwise location x is Rex = 7.2×105. The field of view is around 2S×1.8S, and is captured by two CMOS cameras (2048×2048 pixel) with sampling rate as 500Hz. The averaged resolution is about 8 pixels per Kolmogorov scale (calculated at y/(δ) = 0.6), which is high enough for TNTI-related research (Borrell and Jimenez, 2016). The ´TNTI is detected by the magnitude of local enstrophy ω2/2, and the threshold is selected to be the value where changing the threshold has the smallest influence on the TNTI-mean-height (Watanabe et al., 2018). The time-mean velocity and TNTI location are present in Fig.2(a). A pair of counter-rotating largescale secondary vortices (SVs) are induced over the ridge-type roughness. At the position where SVs induce upwash flow, a low-momentum pathway (LMP) can be observed, while the time-mean height of TNTI (yI) is brought higher. As a contrast, where downwash flow induces high-momentum pathway (HMP), (yI) is lower. TNTI properties are further discussed from two aspect. The geometry properties are firstly investigated. The fractal dimension of the TNTI keeps as 2.3 along the spanwise direction. This value is consistent with the result over smooth plate (Borrell and Jimenez, 2016; Wu et al., 2020) and riblets plates(Cui et al., 2019),´ which indicates that the wall shapes do not influence the multiscale properties of the TNTI. The streamwise wavelength of the TNTI (λI) is further obtained by calculating the streamwise pre-multiplied spectrum of the TNTI. It is found that at each spanwise location, λI is identical to the wavelength of streamwise velocity fluctuation at the TNTI mean height. This shows that the large-scale fluctuation of TNTI is controlled by the large-scale streamwise velocity fluctuation structures. Secondly, the p.d.f. of TNTI instantaneous height is investigated, as shown in Fig. 2(b). It can be observed that the p.d.f. of TNTI height above LMP shows a negative skewness, while the p.d.f. above HMP skews positively. A closer look at instantaneous structures shows that the skewness is attributed to the different probability of Q2/Q4 events in LMP and HMP.


Sign in / Sign up

Export Citation Format

Share Document