In this paper, we survey recent approaches to blue-noise sampling and discuss their beneficial applications. We discuss the sampling algorithms that use points as sampling primitives and classify the sampling algorith...In this paper, we survey recent approaches to blue-noise sampling and discuss their beneficial applications. We discuss the sampling algorithms that use points as sampling primitives and classify the sampling algorithms based on various aspects, e.g., the sampling domain and the type of algorithm. We demonstrate several well-known applications that can be improved by recent blue-noise sampling techniques, as well as some new applications such as dynamic sampling and blue-noise remeshing.展开更多
Laser interference lithography is an attractive method for the fabrication of a large-area two-dimensional planar scale grating,which can be employed as a scale for multi-axis optical encoders or a diffractive optical...Laser interference lithography is an attractive method for the fabrication of a large-area two-dimensional planar scale grating,which can be employed as a scale for multi-axis optical encoders or a diffractive optical element in many types of optical sensors.Especially,optical configurations such as Lloyd's mirror interferometer based on the division of wavefront method can generate interference fringe fields for the patterning of grating pattern structures at a single exposure in a stable manner.For the fabrication of a two-dimensional scale grating to be used in a planar/surface encoder,an orthogonal two-axis Lloyd's mirror interferometer,which has been realized through innovation to Lloyd’s mirror interferometer,has been developed.In addition,the concept of the patterning of the two-dimensional orthogonal pattern structure at a single exposure has been extended to the non-orthogonal two-axis Lloyd’s mirror interferometer.Furthermore,the optical setup for the non-orthogonal two-axis Lloyd's mirror interferometer has been optimized for the fabrication of a large-area scale grating.In this review article,principles of generating interference fringe fields for the fabrication of a scale grating based on the interference lithography are reviewed,while focusing on the fabrication of a two-dimensional scale grating for planar/surface encoders.Verification of the pitch of the fabricated pattern structures,whose accuracy strongly affects the performance of planar/surface encoders,is also an important task to be addressed.In this paper,major methods for the evaluation of a grating pitch are also reviewed.展开更多
Objective: To induce callus from the medicinally valuable species, Barringtonia racemosa L.(B. racemosa) whereby the formation of callus is essential for micropropagation studies and in vitro plant secondary metabolit...Objective: To induce callus from the medicinally valuable species, Barringtonia racemosa L.(B. racemosa) whereby the formation of callus is essential for micropropagation studies and in vitro plant secondary metabolites production.Methods: The callus induction potential in B. racemosa was assessed from endosperm explant cultured on different culture media and plant hormonal treatments. Lloyd and Mc Cown's woody plant medium and Murashige and Skoog's medium were used in the study as culture media. On the other hand, various concentrations and combinations of2,4-dichlorophenoxyacetic acid(1.0–2.0 mg/L) and kinetin(0.5–2.5 mg/L) had been incorporated in the culture media to exert the effects of auxin and cytokinin on callus induction.Results: From the present study, it was found that the profuse [(1.681 ± 0.770) g fresh weight,(0.239 ± 0.239) g dry weight] and friable callus formation was optimally produced with desirable morphology and considerable percentage of callus induction(56.70%) in endosperm explants cultured on 1.0 mg/L 2,4-dichlorophenoxyacetic acid and 1.5 mg/L kinetin in Murashige and Skoog's medium.Conclusions: A reliable protocol for inducing callus formation of profuse and friable morphology in endosperm explant of B. racemosa had therefore been successfully established.展开更多
This paper presents a novel algorithm for identifying quadric surfaces from scanned mechanical models. We make several important improvements over the existing variational 3D shape segmentation framework, which utiliz...This paper presents a novel algorithm for identifying quadric surfaces from scanned mechanical models. We make several important improvements over the existing variational 3D shape segmentation framework, which utilizes Lloyd＇s iteration. First, instead of using randomized initialization （which likely falls into non-optimal minimum）, the RANSAC-based initialization approach is adopted. Given a good initialization, our method converges quickly than previous approaches. Second, in order to enhance the stability and the robustness, we carefully modify the distortion-minimizing flooding algorithm by using seed regions instead of seed triangles. Third, the geometric constraints are introduced into the optimization framework. The segmentation quality is further improved. We validate the efficiency and the robustness of our proposed method on various datasets, and demonstrate that our method outperforms state-of-art approaches.展开更多
Maximal-ratio transmission systems with transmit antenna selection is investigated. According to the order statistics of channel fiat fading coefficients, the closed-form expressions axe derived for average SNR with a...Maximal-ratio transmission systems with transmit antenna selection is investigated. According to the order statistics of channel fiat fading coefficients, the closed-form expressions axe derived for average SNR with any amount of RF chains and average BER with two RF chains, respectively. The algorithm for calculating the minimum of total transmit antennas is presented in terms of reduced RF chains. The method of quantizing transmit precoders is employed in this study to decrease feedback information. Simulation results demonstrate the superiority of the proposed systems under full and quantized transmit precoders. The SNR of the proposed systems has been less degraded by the quantization of transmit precoder than that of pure maximal-ratio transmission systems.展开更多
The theory rhetoric situation put forward by Bitzer is applied to the analysis of President Bush's address on September 11. Such these essential elements as the exigence, audience and constraints will be illustrat...The theory rhetoric situation put forward by Bitzer is applied to the analysis of President Bush's address on September 11. Such these essential elements as the exigence, audience and constraints will be illustrated to reveal the cultural and religious roots behind the September 11 terrorist attack.展开更多
This paper deals with the design and performance analysis of transmit precoder optimization for multiple input multiple output(MIMO) systems with limited feedback of channel state information.A capacity criterion base...This paper deals with the design and performance analysis of transmit precoder optimization for multiple input multiple output(MIMO) systems with limited feedback of channel state information.A capacity criterion based optimal codebook construction algorithm for MIMO precoded spatial multiplexing systems is presented. The optimal precoder structure combining precoding and power allocation is employed.Simulation results show that the capacity criteria based codebook can achieve higher capacity than that of equally power allocation based codebook of previous research.展开更多
5月5日,《自然通讯》发表了中科院古脊椎所王敏、周忠和、邹晶梅与山东临沂大学郑晓廷、王孝理、王岩、张晓梅以及麦考瑞大学Graeme T.Lloyd合作完成的一篇题为＂The oldest record of Ornithuromorpha from the Early Cretaceous of Ch...5月5日,《自然通讯》发表了中科院古脊椎所王敏、周忠和、邹晶梅与山东临沂大学郑晓廷、王孝理、王岩、张晓梅以及麦考瑞大学Graeme T.Lloyd合作完成的一篇题为＂The oldest record of Ornithuromorpha from the Early Cretaceous of China＂的论文,报道了世界上迄今发现的最古老的今鸟型类化石。研究者对收藏于山东天宇自然博物馆的两件鸟类化石。展开更多
In some recent work concerning the number of limit cycles of the planar polynomial differential system, by using the different methods and examples, N. G. Lloyd et al., D. M. Wang, and LIU Yi-rong have successively sh...In some recent work concerning the number of limit cycles of the planar polynomial differential system, by using the different methods and examples, N. G. Lloyd et al., D. M. Wang, and LIU Yi-rong have successively shown that there exist at least six limit cycles bifurcated from the origin in the planar cubic differential system （E<sub>3</sub>）. Namely, the value of cyclicity of multiple Hopf bifurcation （in the sense of Bautin） satisfies M（3）≥6.展开更多
In a variety of modern applications there arises a need to tessellate the domain into representative regions,called Voronoi cells.A particular type of such tessellations,called centroidal Voronoi tessellations or CVTs...In a variety of modern applications there arises a need to tessellate the domain into representative regions,called Voronoi cells.A particular type of such tessellations,called centroidal Voronoi tessellations or CVTs,are in big demand due to their optimality properties important for many applications.The availability of fast and reliable algorithms for their construction is crucial for their successful use in practical settings.This paper introduces a new multigrid algorithm for constructing CVTs that is based on the MG/Opt algorithm that was originally designed to solve large nonlinear optimization problems.Uniform convergence of the new method and its speedup comparing to existing techniques are demonstrated for linear and nonlinear densities for several 1d and 2d problems,and O(k)complexity estimation is provided for a problem with k generators.展开更多
High quality mesh plays an important role for finite element methods in science computation and numerical simulation.Whether the mesh quality is good or not,to some extent,it determines the calculation results of the ...High quality mesh plays an important role for finite element methods in science computation and numerical simulation.Whether the mesh quality is good or not,to some extent,it determines the calculation results of the accuracy and efficiency.Different from classic Lloyd iteration algorithm which is convergent slowly,a novel accelerated scheme was presented,which consists of two core parts:mesh points replacement and local edges Delaunay swapping.By using it,almost all the equilateral triangular meshes can be generated based on centroidal Voronoi tessellation(CVT).Numerical tests show that it is significantly effective with time consuming decreasing by 40%.Compared with other two types of regular mesh generation methods,CVT mesh demonstrates that higher geometric average quality increases over 0.99.展开更多
扣岑(Lloyd Cotsen)先生捐赠的众多铜镜当中不乏历代之精品,其中一枚"两心同长存"莲花人物镜是扣岑先生收藏品中最大的一件,直径33厘米,重2900克(图1,以下简称"扣岑镜")。美国加利福尼亚州圣玛利诺市的亨廷顿图书...扣岑(Lloyd Cotsen)先生捐赠的众多铜镜当中不乏历代之精品,其中一枚"两心同长存"莲花人物镜是扣岑先生收藏品中最大的一件,直径33厘米,重2900克(图1,以下简称"扣岑镜")。美国加利福尼亚州圣玛利诺市的亨廷顿图书馆专门为他的铜镜收藏举办过一个展览,并且出版图录The Lloyd Cotsen Study Collection of Chinese Bronze Mirrors(Volume I:Catalogue)编撰者把这件铜镜的年代定在唐代。展开更多
基金This work was partially supported by the National Natural Science Foundation of China under Grant Nos. 61372168, 61373071, 61372190, and 61331018, the Scientific Research Foundation for the Returned Overseas Chinese Scholars of State Education Ministry of China, the Visual Computing Center at King Abudullah University of Science and Technology （KAUST）, and the Open Funding Project of the State Key Laboratory of Virtual Reality Technology and Systems, Beihang University, under Grant Nos. BUAA-VR- 15KF-06 and BUAA-VR-14KF-10.
文摘In this paper, we survey recent approaches to blue-noise sampling and discuss their beneficial applications. We discuss the sampling algorithms that use points as sampling primitives and classify the sampling algorithms based on various aspects, e.g., the sampling domain and the type of algorithm. We demonstrate several well-known applications that can be improved by recent blue-noise sampling techniques, as well as some new applications such as dynamic sampling and blue-noise remeshing.
基金supported by the Japan Society for the Promotion of Science(JSPS).The author would like to thank Professor Wei Gao(Tohoku University,Japan)for the fruitful discussions and valuable comments on the topic of this review article.
文摘Laser interference lithography is an attractive method for the fabrication of a large-area two-dimensional planar scale grating,which can be employed as a scale for multi-axis optical encoders or a diffractive optical element in many types of optical sensors.Especially,optical configurations such as Lloyd's mirror interferometer based on the division of wavefront method can generate interference fringe fields for the patterning of grating pattern structures at a single exposure in a stable manner.For the fabrication of a two-dimensional scale grating to be used in a planar/surface encoder,an orthogonal two-axis Lloyd's mirror interferometer,which has been realized through innovation to Lloyd’s mirror interferometer,has been developed.In addition,the concept of the patterning of the two-dimensional orthogonal pattern structure at a single exposure has been extended to the non-orthogonal two-axis Lloyd’s mirror interferometer.Furthermore,the optical setup for the non-orthogonal two-axis Lloyd's mirror interferometer has been optimized for the fabrication of a large-area scale grating.In this review article,principles of generating interference fringe fields for the fabrication of a scale grating based on the interference lithography are reviewed,while focusing on the fabrication of a two-dimensional scale grating for planar/surface encoders.Verification of the pitch of the fabricated pattern structures,whose accuracy strongly affects the performance of planar/surface encoders,is also an important task to be addressed.In this paper,major methods for the evaluation of a grating pitch are also reviewed.
基金Supported by Ministry of Education under Higher Education Department through Fundamental Research Grant Scheme(FRGS)with the grant number of FRGS/1/2012/STW/N03/UITM/02/01
文摘Objective: To induce callus from the medicinally valuable species, Barringtonia racemosa L.(B. racemosa) whereby the formation of callus is essential for micropropagation studies and in vitro plant secondary metabolites production.Methods: The callus induction potential in B. racemosa was assessed from endosperm explant cultured on different culture media and plant hormonal treatments. Lloyd and Mc Cown's woody plant medium and Murashige and Skoog's medium were used in the study as culture media. On the other hand, various concentrations and combinations of2,4-dichlorophenoxyacetic acid(1.0–2.0 mg/L) and kinetin(0.5–2.5 mg/L) had been incorporated in the culture media to exert the effects of auxin and cytokinin on callus induction.Results: From the present study, it was found that the profuse [(1.681 ± 0.770) g fresh weight,(0.239 ± 0.239) g dry weight] and friable callus formation was optimally produced with desirable morphology and considerable percentage of callus induction(56.70%) in endosperm explants cultured on 1.0 mg/L 2,4-dichlorophenoxyacetic acid and 1.5 mg/L kinetin in Murashige and Skoog's medium.Conclusions: A reliable protocol for inducing callus formation of profuse and friable morphology in endosperm explant of B. racemosa had therefore been successfully established.
基金Supported by the National Natural Science Foundation of China(61372168,61620106003 and 61331018)
文摘This paper presents a novel algorithm for identifying quadric surfaces from scanned mechanical models. We make several important improvements over the existing variational 3D shape segmentation framework, which utilizes Lloyd＇s iteration. First, instead of using randomized initialization （which likely falls into non-optimal minimum）, the RANSAC-based initialization approach is adopted. Given a good initialization, our method converges quickly than previous approaches. Second, in order to enhance the stability and the robustness, we carefully modify the distortion-minimizing flooding algorithm by using seed regions instead of seed triangles. Third, the geometric constraints are introduced into the optimization framework. The segmentation quality is further improved. We validate the efficiency and the robustness of our proposed method on various datasets, and demonstrate that our method outperforms state-of-art approaches.
基金the National Natural Science Foundation of China (60472103)Shanghai Excellent Academic Leader Project (05XP14027)Shanghai Leading Academic Discipline Project(T0102).
文摘Maximal-ratio transmission systems with transmit antenna selection is investigated. According to the order statistics of channel fiat fading coefficients, the closed-form expressions axe derived for average SNR with any amount of RF chains and average BER with two RF chains, respectively. The algorithm for calculating the minimum of total transmit antennas is presented in terms of reduced RF chains. The method of quantizing transmit precoders is employed in this study to decrease feedback information. Simulation results demonstrate the superiority of the proposed systems under full and quantized transmit precoders. The SNR of the proposed systems has been less degraded by the quantization of transmit precoder than that of pure maximal-ratio transmission systems.
文摘The theory rhetoric situation put forward by Bitzer is applied to the analysis of President Bush's address on September 11. Such these essential elements as the exigence, audience and constraints will be illustrated to reveal the cultural and religious roots behind the September 11 terrorist attack.
基金The National Natural Science Foundationof China(No.60572157)
文摘This paper deals with the design and performance analysis of transmit precoder optimization for multiple input multiple output(MIMO) systems with limited feedback of channel state information.A capacity criterion based optimal codebook construction algorithm for MIMO precoded spatial multiplexing systems is presented. The optimal precoder structure combining precoding and power allocation is employed.Simulation results show that the capacity criteria based codebook can achieve higher capacity than that of equally power allocation based codebook of previous research.
文摘5月5日,《自然通讯》发表了中科院古脊椎所王敏、周忠和、邹晶梅与山东临沂大学郑晓廷、王孝理、王岩、张晓梅以及麦考瑞大学Graeme T.Lloyd合作完成的一篇题为＂The oldest record of Ornithuromorpha from the Early Cretaceous of China＂的论文,报道了世界上迄今发现的最古老的今鸟型类化石。研究者对收藏于山东天宇自然博物馆的两件鸟类化石。
基金Project supported by the National Natural Science Foundation of China.
文摘In some recent work concerning the number of limit cycles of the planar polynomial differential system, by using the different methods and examples, N. G. Lloyd et al., D. M. Wang, and LIU Yi-rong have successively shown that there exist at least six limit cycles bifurcated from the origin in the planar cubic differential system （E<sub>3</sub>）. Namely, the value of cyclicity of multiple Hopf bifurcation （in the sense of Bautin） satisfies M（3）≥6.
基金supported by the U.S.Department of Energy under Award DE-SC-0001691support from the ORAU Ralph E.Powe Junior Faculty Enhancement Award and from the National Science Foundation under the grants DMS-1056821 and DMS-0915013.
文摘In a variety of modern applications there arises a need to tessellate the domain into representative regions,called Voronoi cells.A particular type of such tessellations,called centroidal Voronoi tessellations or CVTs,are in big demand due to their optimality properties important for many applications.The availability of fast and reliable algorithms for their construction is crucial for their successful use in practical settings.This paper introduces a new multigrid algorithm for constructing CVTs that is based on the MG/Opt algorithm that was originally designed to solve large nonlinear optimization problems.Uniform convergence of the new method and its speedup comparing to existing techniques are demonstrated for linear and nonlinear densities for several 1d and 2d problems,and O(k)complexity estimation is provided for a problem with k generators.
基金Project(11002121) supported by the National Natural Science Foundation of ChinaProject(09QDZ09) supported by Doctor Foundation of Xiangtan University, China+2 种基金Project(2009LCSSE11) supported by Hunan Key Laboratory for CSSE, ChinaProject(2011FJ3231) supported by Planned Science and Technology Project of Hunan Province,ChinaProject(12JJ3054) supported by the Provincial Natural Science Foundation of Hunan,China
文摘High quality mesh plays an important role for finite element methods in science computation and numerical simulation.Whether the mesh quality is good or not,to some extent,it determines the calculation results of the accuracy and efficiency.Different from classic Lloyd iteration algorithm which is convergent slowly,a novel accelerated scheme was presented,which consists of two core parts:mesh points replacement and local edges Delaunay swapping.By using it,almost all the equilateral triangular meshes can be generated based on centroidal Voronoi tessellation(CVT).Numerical tests show that it is significantly effective with time consuming decreasing by 40%.Compared with other two types of regular mesh generation methods,CVT mesh demonstrates that higher geometric average quality increases over 0.99.
文摘扣岑(Lloyd Cotsen)先生捐赠的众多铜镜当中不乏历代之精品,其中一枚"两心同长存"莲花人物镜是扣岑先生收藏品中最大的一件,直径33厘米,重2900克(图1,以下简称"扣岑镜")。美国加利福尼亚州圣玛利诺市的亨廷顿图书馆专门为他的铜镜收藏举办过一个展览,并且出版图录The Lloyd Cotsen Study Collection of Chinese Bronze Mirrors(Volume I:Catalogue)编撰者把这件铜镜的年代定在唐代。
