An abrasive free chemical mechanical planarization（AFCMP） of semi-polar（1122） Al N surface has been demonstrated. The effect of slurry p H, polishing pressure, and platen velocity on the material removal rate（MRR...An abrasive free chemical mechanical planarization（AFCMP） of semi-polar（1122） Al N surface has been demonstrated. The effect of slurry p H, polishing pressure, and platen velocity on the material removal rate（MRR） and surface quality（RMS roughness） have been studied. The effect of polishing pressure on the AFCMP of the（1122） Al N surface has been compared with that of the（1122） Al Ga N surface. The maximum MRR has been found to be 562 nm/h for the semi-polar（1122） Al N surface, under the experimental conditions of 38 k Pa pressure,90 rpm platen velocity, 30 rpm carrier velocity, slurry p H 3 and 0.4 M oxidizer concentration. The best root mean square（RMS） surface roughness of 1.2 nm and 0.7 nm, over a large scanning area of 0.70×0.96 mm^2, has been achieved on AFCMP processed semi-polar（1122） AlN and（AlGaN） surfaces using optimized slurry chemistry and processing parameters.展开更多
The relationship between a link diagram and its corresponding planar graph is briefly reviewed. A necessary and sufficient condition is given to detect when a planar graph corresponds to a knot. The relationship betwe...The relationship between a link diagram and its corresponding planar graph is briefly reviewed. A necessary and sufficient condition is given to detect when a planar graph corresponds to a knot. The relationship between planar graph and almost planar Seifert surface is discussed. Using planar graph, we construct an alternating amphicheiral prime knot with crossing number n for any even number n 〉 4. This gives an affirmative answer to problem 1.66（B） on Kirby＇s problem list .展开更多
Let Hn be an orientable handlebody of genus n. It has been proved that for n not less than 2, there exists an annulus-busting curve in δHm. In the present paper, we prove that for n not less than 2, there exists an e...Let Hn be an orientable handlebody of genus n. It has been proved that for n not less than 2, there exists an annulus-busting curve in δHm. In the present paper, we prove that for n not less than 2, there exists an essential simple closed curve C in OHm which intersects each essential planar surface in Hn non-emptily. Furthermore, we show that for n not less than 3, a pants-busting curve must also be an annulus-busting curve.展开更多
Different processes are used on the back surface of silicon wafers to form cells falling into three groups：textured, planar, and sawed-off pyramid back surface.The characteristic parameters of the cells, ISC, VOC, FF...Different processes are used on the back surface of silicon wafers to form cells falling into three groups：textured, planar, and sawed-off pyramid back surface.The characteristic parameters of the cells, ISC, VOC, FF, Pm, and Eff, are measured.All these parameters of the planar back surface cells are the best.The FF, Pm, and Eff of sawed-off pyramid back surface cells are superior to textured back surface cells, although ISC and VOC are lower.The parasitic resistance is analyzed to explain the higher FF of the sawed-off pyramid back surface cells.The cross-section scanning electron microscopy（SEM） pictures show the uniformity of the aluminum-silicon alloy, which has an important effect on the back surface recombination velocity and the ohmic contact.The measured value of the aluminum back surface field thickness in the SEM picture is in good agreement with the theoretical value deduced from the Al-Si phase diagram.It is shown in an external quantum efficiency（EQE） diagram that the planar back surface has the best response to a wavelength between 440 and 1000 nm and the sawed-off back surface has a better long wavelength response.展开更多
We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectro...We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.展开更多
Tessellations have been widely used in architectural designs to create visually striking surfaces by repeating a small number of elements.While there has been extensive research on 2D tiling over the past 2000 years,t...Tessellations have been widely used in architectural designs to create visually striking surfaces by repeating a small number of elements.While there has been extensive research on 2D tiling over the past 2000 years,this study focuses on the systematic development of a technique for the modular construction of 2D tiling with 3D texture surfaces using identical tiles,which is of great importance in architectural designs for cost-effective constructions through the mass production of repeating components.This study applies parametric geometrical modelling using Grasshopper scripting to generate a wide range of 3D reliefs on planar surfaces by repeating a single tile or a few different tiles.Based on the findings of this study,it is possible to arrange tiles with an identical 3D texture surface in multiple configurations,resulting in a range of 3D reliefs on tessellated surfaces that exhibit smooth transitions across adjacent tiles.A significant application of this technique is in producing stunning facades and other 3D surfaces using identical modules,offering affordable modular construction through repetition.The study also demonstrates the versatility of the technique by creating various attractive non-periodic 3D surfaces using triangular,square,hexagonal,or even non-regular tiles.展开更多
Indoor visual localization,i.e.,6 Degree-of-Freedom camera pose estimation for a query image with respect to a known scene,is gaining increased attention driven by rapid progress of applications such as robotics and a...Indoor visual localization,i.e.,6 Degree-of-Freedom camera pose estimation for a query image with respect to a known scene,is gaining increased attention driven by rapid progress of applications such as robotics and augmented reality.However,drastic visual discrepancies between an onsite query image and prerecorded indoor images cast a significant challenge for visual localization.In this paper,based on the key observation of the constant existence of planar surfaces such as floors or walls in indoor scenes,we propose a novel system incorporating geometric information to address issues using only pixelated images.Through the system implementation,we contribute a hierarchical structure consisting of pre-scanned images and point cloud,as well as a distilled representation of the planar-element layout extracted from the original dataset.A view synthesis procedure is designed to generate synthetic images as complementary to that of a sparsely sampled dataset.Moreover,a global image descriptor based on the image statistic modality,called block mean,variance,and color(BMVC),was employed to speed up the candidate pose identification incorporated with a traditional convolutional neural network(CNN)descriptor.Experimental results on a popular benchmark demonstrate that the proposed method outperforms the state-of-the-art approaches in terms of visual localization validity and accuracy.展开更多
基金financial support from the Department of Science and Technology(DST),Government of India(No,SR/S2/Cmp-0009/2011)partial support from the Board of Research in Nuclear Sciences(BRNS),Department of Atomic Energy(DAE),Government of India(No.-34/14/43/2014-BRNS)with ATC
文摘An abrasive free chemical mechanical planarization（AFCMP） of semi-polar（1122） Al N surface has been demonstrated. The effect of slurry p H, polishing pressure, and platen velocity on the material removal rate（MRR） and surface quality（RMS roughness） have been studied. The effect of polishing pressure on the AFCMP of the（1122） Al N surface has been compared with that of the（1122） Al Ga N surface. The maximum MRR has been found to be 562 nm/h for the semi-polar（1122） Al N surface, under the experimental conditions of 38 k Pa pressure,90 rpm platen velocity, 30 rpm carrier velocity, slurry p H 3 and 0.4 M oxidizer concentration. The best root mean square（RMS） surface roughness of 1.2 nm and 0.7 nm, over a large scanning area of 0.70×0.96 mm^2, has been achieved on AFCMP processed semi-polar（1122） AlN and（AlGaN） surfaces using optimized slurry chemistry and processing parameters.
文摘The relationship between a link diagram and its corresponding planar graph is briefly reviewed. A necessary and sufficient condition is given to detect when a planar graph corresponds to a knot. The relationship between planar graph and almost planar Seifert surface is discussed. Using planar graph, we construct an alternating amphicheiral prime knot with crossing number n for any even number n 〉 4. This gives an affirmative answer to problem 1.66（B） on Kirby＇s problem list .
基金The grant (09XBKQ09) of Harbin Normal Universitythe NSF (11101058) of ChinaChina Postdoctoral Science Foundation (2011M500049)
文摘Let Hn be an orientable handlebody of genus n. It has been proved that for n not less than 2, there exists an annulus-busting curve in δHm. In the present paper, we prove that for n not less than 2, there exists an essential simple closed curve C in OHm which intersects each essential planar surface in Hn non-emptily. Furthermore, we show that for n not less than 3, a pants-busting curve must also be an annulus-busting curve.
文摘Different processes are used on the back surface of silicon wafers to form cells falling into three groups：textured, planar, and sawed-off pyramid back surface.The characteristic parameters of the cells, ISC, VOC, FF, Pm, and Eff, are measured.All these parameters of the planar back surface cells are the best.The FF, Pm, and Eff of sawed-off pyramid back surface cells are superior to textured back surface cells, although ISC and VOC are lower.The parasitic resistance is analyzed to explain the higher FF of the sawed-off pyramid back surface cells.The cross-section scanning electron microscopy（SEM） pictures show the uniformity of the aluminum-silicon alloy, which has an important effect on the back surface recombination velocity and the ohmic contact.The measured value of the aluminum back surface field thickness in the SEM picture is in good agreement with the theoretical value deduced from the Al-Si phase diagram.It is shown in an external quantum efficiency（EQE） diagram that the planar back surface has the best response to a wavelength between 440 and 1000 nm and the sawed-off back surface has a better long wavelength response.
文摘We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.
基金financial support provided by the Australian Research Council(FL190100014,DP200102190).
文摘Tessellations have been widely used in architectural designs to create visually striking surfaces by repeating a small number of elements.While there has been extensive research on 2D tiling over the past 2000 years,this study focuses on the systematic development of a technique for the modular construction of 2D tiling with 3D texture surfaces using identical tiles,which is of great importance in architectural designs for cost-effective constructions through the mass production of repeating components.This study applies parametric geometrical modelling using Grasshopper scripting to generate a wide range of 3D reliefs on planar surfaces by repeating a single tile or a few different tiles.Based on the findings of this study,it is possible to arrange tiles with an identical 3D texture surface in multiple configurations,resulting in a range of 3D reliefs on tessellated surfaces that exhibit smooth transitions across adjacent tiles.A significant application of this technique is in producing stunning facades and other 3D surfaces using identical modules,offering affordable modular construction through repetition.The study also demonstrates the versatility of the technique by creating various attractive non-periodic 3D surfaces using triangular,square,hexagonal,or even non-regular tiles.
基金supported by the National Natural Science Foundation of China under Grant Nos.62072284 and 61772318the Special Project of Science and Technology Innovation Base of Key Laboratory of Shandong Province for Software Engineering under Grant No.11480004042015。
文摘Indoor visual localization,i.e.,6 Degree-of-Freedom camera pose estimation for a query image with respect to a known scene,is gaining increased attention driven by rapid progress of applications such as robotics and augmented reality.However,drastic visual discrepancies between an onsite query image and prerecorded indoor images cast a significant challenge for visual localization.In this paper,based on the key observation of the constant existence of planar surfaces such as floors or walls in indoor scenes,we propose a novel system incorporating geometric information to address issues using only pixelated images.Through the system implementation,we contribute a hierarchical structure consisting of pre-scanned images and point cloud,as well as a distilled representation of the planar-element layout extracted from the original dataset.A view synthesis procedure is designed to generate synthetic images as complementary to that of a sparsely sampled dataset.Moreover,a global image descriptor based on the image statistic modality,called block mean,variance,and color(BMVC),was employed to speed up the candidate pose identification incorporated with a traditional convolutional neural network(CNN)descriptor.Experimental results on a popular benchmark demonstrate that the proposed method outperforms the state-of-the-art approaches in terms of visual localization validity and accuracy.
