Progressive geometric algorithms
Directory of Open Access Journals (Sweden)
Sander P.A. Alewijnse
2015-01-01
Full Text Available Progressive algorithms are algorithms that, on the way to computing a complete solution to the problem at hand, output intermediate solutions that approximate the complete solution increasingly well. We present a framework for analyzing such algorithms, and develop efficient progressive algorithms for two geometric problems: computing the convex hull of a planar point set, and finding popular places in a set of trajectories.
MM Algorithms for Geometric and Signomial Programming.
Lange, Kenneth; Zhou, Hua
2014-02-01
This paper derives new algorithms for signomial programming, a generalization of geometric programming. The algorithms are based on a generic principle for optimization called the MM algorithm. In this setting, one can apply the geometric-arithmetic mean inequality and a supporting hyperplane inequality to create a surrogate function with parameters separated. Thus, unconstrained signomial programming reduces to a sequence of one-dimensional minimization problems. Simple examples demonstrate that the MM algorithm derived can converge to a boundary point or to one point of a continuum of minimum points. Conditions under which the minimum point is unique or occurs in the interior of parameter space are proved for geometric programming. Convergence to an interior point occurs at a linear rate. Finally, the MM framework easily accommodates equality and inequality constraints of signomial type. For the most important special case, constrained quadratic programming, the MM algorithm involves very simple updates.
Institute of Scientific and Technical Information of China (English)
WANG ShunJin; ZHANG Hua
2007-01-01
Based on the exact analytical solution of ordinary differential equations,a truncation of the Taylor series of the exact solution to the Nth order leads to the Nth order algebraic dynamics algorithm.A detailed numerical comparison is presented with Runge-Kutta algorithm and symplectic geometric algorithm for 12 test models.The results show that the algebraic dynamics algorithm can better preserve both geometrical and dynamical fidelity of a dynamical system at a controllable precision,and it can solve the problem of algorithm-induced dissipation for the Runge-Kutta algorithm and the problem of algorithm-induced phase shift for the symplectic geometric algorithm.
Institute of Scientific and Technical Information of China (English)
2007-01-01
Based on the exact analytical solution of ordinary differential equations, a truncation of the Taylor series of the exact solution to the Nth order leads to the Nth order algebraic dynamics algorithm. A detailed numerical comparison is presented with Runge-Kutta algorithm and symplectic geometric algorithm for 12 test models. The results show that the algebraic dynamics algorithm can better preserve both geometrical and dynamical fidelity of a dynamical system at a controllable precision, and it can solve the problem of algorithm-induced dissipation for the Runge-Kutta algorithm and the problem of algorithm-induced phase shift for the symplectic geometric algorithm.
DEFF Research Database (Denmark)
Forsingdal, Charlotte Vartou; Lauridsen, Vagn Holk; Hougaard, Karsten Frøhlich
opfyldelsen af 2020-målene, skal de rette kompetencer inden for energief-fektivitet og brug af vedvarende energi være til stede blandt de udførende i bygge- og an-lægsbranchen. Det er på denne baggrund, at Europa-Kommissionen har igangsat Build Up Skills projektet på tværs af Europa. Formålet med denne...
Geometric Algorithm for Received Signal Strength Based Mobile Positioning
Directory of Open Access Journals (Sweden)
J. Duha
2005-06-01
Full Text Available Mobile positioning is one of the fastest growing areas for thedevelopment of new technologies, services and applications. This paperdescribes a simple and efficient geometric algorithm using receivedsignal strength measurements extracted from at least three basestations. This method is compared with standard Least Squares method.The simulation results show, that geometric algorithm gives moreaccurately location estimation than LS algorithm in multipathpropagation.
Geometric Algorithms for Part Orienting and Probing
Panahi, F.
2015-01-01
In this thesis, detailed solutions are presented to several problems dealing with geometric shape and orientation of an object in the field of robotics and automation. We first have considered a general model for shape variations that allows variation along the entire boundary of an object, both in
CCH-based geometric algorithms for SVM and applications
Institute of Scientific and Technical Information of China (English)
Xin-jun PENG; Yi-fei WANG
2009-01-01
The support vector machine (SVM) is a novel machine learning tool in data mining. In this paper, the geometric approach based on the compressed convex hull (CCH) with a mathematical framework is introduced to solve SVM classification problems. Compared with the reduced convex hull (RCH), CCH preserves the shape of geometric solids for data sets; meanwhile, it is easy to give the necessary and sufficient condition for determining its extreme points. As practical applications of CCH, spare and probabilistic speed-up geometric algorithms are developed. Results of numerical experiments show that the proposed algorithms can reduce kernel calculations and display nice performances.
Geometric Algorithms for Private-Cache Chip Multiprocessors
DEFF Research Database (Denmark)
Ajwani, Deepak; Sitchinava, Nodari; Zeh, Norbert
2010-01-01
We study techniques for obtaining efficient algorithms for geometric problems on private-cache chip multiprocessors. We show how to obtain optimal algorithms for interval stabbing counting, 1-D range counting, weighted 2-D dominance counting, and for computing 3-D maxima, 2-D lower envelopes, and 2...
A TRANSFORMATION PATH ALGORITHM FOR UNCONSTRAINED SIGNOMIAL GEOMETRIC PROGRAMMING
Institute of Scientific and Technical Information of China (English)
王燕军; 张可村
2004-01-01
In this paper we present a transformation path algorithm for Unconstrained Signomial Geometric Programming (USGP). The algorithm is proposed from a new point of view based on exploring the characteristics of USGP problem. Firstly by some stable transformations, a particular subproblem is derived which is very easy to solve.Secondly, a special path is formed conveniently. And then the step of the algorithm consists in finding a "good" point to the current iterate by choosing it along the special path and within a trust region. It is proved that the algorithm is globally convergent.
Scalable parallel geometric algorithms for coarse grained multicomputers
Dehne, Franck; Fabri, Andreas; Rau-Chaplin, Andrew
1992-01-01
Whereas most of the literature assumes that the number of processors p is a function of the problem size n, in scalable algorithms p becomes a parameter of the time complexity. This is a more realistic modelisation of real parallel machines and yields optimal algorithms, for the case that n H p, where H is a function depending on the architecture of the interconnexion network. In this paper we present scalable algorithms for a number of geometric problems, namely lower envelope of line segmen...
A Robust Image Hashing Algorithm Resistant Against Geometrical Attacks
Directory of Open Access Journals (Sweden)
Y.L. Liu
2013-12-01
Full Text Available This paper proposes a robust image hashing method which is robust against common image processing attacks and geometric distortion attacks. In order to resist against geometric attacks, the log-polar mapping (LPM and contourlet transform are employed to obtain the low frequency sub-band image. Then the sub-band image is divided into some non-overlapping blocks, and low and middle frequency coefficients are selected from each block after discrete cosine transform. The singular value decomposition (SVD is applied in each block to obtain the first digit of the maximum singular value. Finally, the features are scrambled and quantized as the safe hash bits. Experimental results show that the algorithm is not only resistant against common image processing attacks and geometric distortion attacks, but also discriminative to content changes.
Algorithms to automatically quantify the geometric similarity of anatomical surfaces
Boyer, D; Clair, E St; Puente, J; Funkhouser, T; Patel, B; Jernvall, J; Daubechies, I
2011-01-01
We describe new approaches for distances between pairs of 2-dimensional surfaces (embedded in 3-dimensional space) that use local structures and global information contained in inter-structure geometric relationships. We present algorithms to automatically determine these distances as well as geometric correspondences. This is motivated by the aspiration of students of natural science to understand the continuity of form that unites the diversity of life. At present, scientists using physical traits to study evolutionary relationships among living and extinct animals analyze data extracted from carefully defined anatomical correspondence points (landmarks). Identifying and recording these landmarks is time consuming and can be done accurately only by trained morphologists. This renders these studies inaccessible to non-morphologists, and causes phenomics to lag behind genomics in elucidating evolutionary patterns. Unlike other algorithms presented for morphological correspondences our approach does not requir...
Solving geometric constraints with genetic simulated annealing algorithm
Institute of Scientific and Technical Information of China (English)
刘生礼; 唐敏; 董金祥
2003-01-01
This paper applies genetic simulated annealing algorithm (SAGA) to solving geometric constraint problems. This method makes full use of the advantages of SAGA and can handle under-/over- constraint problems naturally. It has advantages (due to its not being sensitive to the initial values) over the Newton-Raphson method, and its yielding of multiple solutions, is an advantage over other optimal methods for multi-solution constraint system. Our experiments have proved the robustness and efficiency of this method.
A Geometric Clustering Algorithm with Applications to Structural Data
Xu, Shutan; Zou, Shuxue
2015-01-01
Abstract An important feature of structural data, especially those from structural determination and protein-ligand docking programs, is that their distribution could be mostly uniform. Traditional clustering algorithms developed specifically for nonuniformly distributed data may not be adequate for their classification. Here we present a geometric partitional algorithm that could be applied to both uniformly and nonuniformly distributed data. The algorithm is a top-down approach that recursively selects the outliers as the seeds to form new clusters until all the structures within a cluster satisfy a classification criterion. The algorithm has been evaluated on a diverse set of real structural data and six sets of test data. The results show that it is superior to the previous algorithms for the clustering of structural data and is similar to or better than them for the classification of the test data. The algorithm should be especially useful for the identification of the best but minor clusters and for speeding up an iterative process widely used in NMR structure determination. PMID:25517067
Finite-size geometric entanglement from tensor network algorithms
Energy Technology Data Exchange (ETDEWEB)
Shi Qianqian; Zhou Huanqiang [Centre for Modern Physics and Department of Physics, Chongqing University, Chongqing 400044 (China); Orus, Roman; Fjaerestad, John Ove [University of Queensland, Department of Physics, Brisbane, QLD 4072 (Australia)], E-mail: orus@physics.uq.edu.au
2010-02-15
The global geometric entanglement (GE) is studied in the context of newly developed tensor network algorithms for finite systems. For one-dimensional quantum spin systems it is found that, at criticality, the leading finite-size correction to the global GE per site behaves as b/n, where n is the size of the system and b a given coefficient. Our conclusion is based on the computation of the GE per spin for the quantum Ising model in a transverse magnetic field and for the spin-1/2 XXZ model. We also discuss the possibility of coefficient b being universal.
A geometric reasoning based algorithm for point pattern matching
Institute of Scientific and Technical Information of China (English)
徐文立; 张立华
2001-01-01
Point pattern matching (PPM) is an important topic in computer vision and pattern recognition. It can be widely used in many areas such as image registration, object recognition, motion detection, target tracking, autonomous navigation, and pose estimation. This paper discusses the incomplete matching problem of two point sets under Euclidean transformation. According to geometric reasoning, some definitions for matching clique, support point pair, support index set, and support index matrix, etc. are given. Based on the properties and theorems of them, a novel reasoning algorithm is presented, which searches for the optimal sOlLtion from top to bottom and could find out as many consistent corresponding point pairs as possible. Theoretical analysis and experimental results show that the new algorithm is very effective, and could be, under some conditions, applied to the PPM problem under other kind of transformations.
Geometric Algorithms for Identifying and Reconstructing Galaxy Systems
Marinoni, C
2010-01-01
The theme of this book chapter is to discuss algorithms for identifying and reconstructing groups and clusters of galaxies out of the general galaxy distribution. I review the progress of detection techniques through time, from the very first visual-like algorithms to the most performant geometrical methods available today. This will allow readers to understand the development of the field as well as the various issues and pitfalls we are confronted with. This essay is drawn from a talk given by the author at the conference "The World a Jigsaw: Tessellations in the Sciences" held at the Lorentz Center in Leiden. It is intended for a broad audience of scientists (and so does not include full academic referencing), but it may be of interest to specialists.
Efficient geometric rectification techniques for spectral analysis algorithm
Chang, C. Y.; Pang, S. S.; Curlander, J. C.
1992-01-01
The spectral analysis algorithm is a viable technique for processing synthetic aperture radar (SAR) data in near real time throughput rates by trading the image resolution. One major challenge of the spectral analysis algorithm is that the output image, often referred to as the range-Doppler image, is represented in the iso-range and iso-Doppler lines, a curved grid format. This phenomenon is known to be the fanshape effect. Therefore, resampling is required to convert the range-Doppler image into a rectangular grid format before the individual images can be overlaid together to form seamless multi-look strip imagery. An efficient algorithm for geometric rectification of the range-Doppler image is presented. The proposed algorithm, realized in two one-dimensional resampling steps, takes into consideration the fanshape phenomenon of the range-Doppler image as well as the high squint angle and updates of the cross-track and along-track Doppler parameters. No ground reference points are required.
Constant-work-space algorithms for geometric problems
Directory of Open Access Journals (Sweden)
Tetsuo Asano
2011-07-01
Full Text Available Constant-work-space algorithms may use only constantly many cells of storage in addition to their input, which is provided as a read-only array. We show how to construct several geometric structures efficiently in the constant-work-space model. Traditional algorithms process the input into a suitable data structure (like a doubly-connected edge list that allows efficient traversal of the structure at hand. In the constant-work-space setting, however, we cannot afford to do this. Instead, we provide operations that compute the desired features on the fly by accessing the input with no extra space. The whole geometric structure can be obtained by using these operations to enumerate all the features. Of course, we must pay for the space savings by slower running times. While the standard data structure allows us to implement traversal operations in constant time, our schemes typically take linear time to read the input data in each step.We begin with two simple problems: triangulating a planar point set and finding the trapezoidal decomposition of a simple polygon. In both cases adjacent features can be enumerated in linear time per step, resulting in total quadratic running time to output the whole structure. Actually, we show that the former result carries over to the Delaunay triangulation, and hence the Voronoi diagram. This also means that we can compute the largest empty circle of a planar point set in quadratic time and constant work-space. As another application, we demonstrate how to enumerate the features of an Euclidean minimum spanning tree (EMST in quadratic time per step, so that the whole EMST can be found in cubic time using constant work-space.Finally, we describe how to compute a shortest geodesic path between two points in a simple polygon. Although the shortest path problem in general graphs is NL-complete (Jakoby and Tantau 2003, this constrained problem can be solved in quadratic time using only constant work-space.
DEFF Research Database (Denmark)
Conrad, Finn; Zhou, Jianjun; Gabacik, Andrzej;
1998-01-01
Invited paper presents a new control algorithm based on feed-forward geometrical compensation strategy combined with adaptive feedback control.......Invited paper presents a new control algorithm based on feed-forward geometrical compensation strategy combined with adaptive feedback control....
Serra, Romain; Valette, Anne; Taji, Amine; Emsley, Stephen
2017-04-01
Building climate resilience (i.e. climate change adaptation or self-renew of ecosystems) or planning environment rehabilitations and nature-based solutions to address their vulnerabilities to disturbances has prerequisites: 1- identify the disorder, i.e. stresses caused by events such as hurricanes, tsunamis, heavy rains, hailstone falls, smog… or piled-up along-time such as warming, rainfalls, ocean acidification, soil salinization… and measured by trends; and 2- qualify its impact on the ecosystems, i.e. the resulting strains. Mitigation of threats is accordingly twofold, i. on locally temporal scales for protection, ii. on long scale for prevention and sustainability. For assessment and evaluation prior to design future scenarios, it requires concomitant acquisition of (a) climate data at global and local spatial scale which describe the changes at the various temporal scales of phenomena without signal aliasing, and of (b) the ecosystems' status at the scales of the forcing and of relaxation times, hysteresis lags, periodicities of orbits in chaotic systems, shifts from one attractor in ecosystems to the others, etc. Dissociating groups of timescales and spatial scales facilitates the analysis and help set-up monitoring schemes. The Sentinel-2 mission, with a revisit of the earth every few days and a 10m resolution on-ground is a good automatic spectro-analytical monitoring system because detecting changes in numerous optical & IR bands at proper spatial scales for the description of land parcels. Combined with photo-interpreted VHR data which describe the environment more crudely but with high precision of land parcels' border locations, it helps find the relationship between stress and strains to empirically understand the relationships. An example is provided for Tonga, courtesy of ESA support and ADB request, with a focus on time-series' consistency that requires radiometric and geometric normalisation of EO data sets. Methodologies have been developed
Ham, Woonchul; Song, Chulgyu; Lee, Kangsan; Roh, Seungkuk
2016-05-01
In this paper, we propose a new image reconstruction algorithm considering the geometric information of acoustic sources and senor detector and review the two-step reconstruction algorithm which was previously proposed based on the geometrical information of ROI(region of interest) considering the finite size of acoustic sensor element. In a new image reconstruction algorithm, not only mathematical analysis is very simple but also its software implementation is very easy because we don't need to use the FFT. We verify the effectiveness of the proposed reconstruction algorithm by showing the simulation results by using Matlab k-wave toolkit.
An improved image compression algorithm using binary space partition scheme and geometric wavelets.
Chopra, Garima; Pal, A K
2011-01-01
Geometric wavelet is a recent development in the field of multivariate nonlinear piecewise polynomials approximation. The present study improves the geometric wavelet (GW) image coding method by using the slope intercept representation of the straight line in the binary space partition scheme. The performance of the proposed algorithm is compared with the wavelet transform-based compression methods such as the embedded zerotree wavelet (EZW), the set partitioning in hierarchical trees (SPIHT) and the embedded block coding with optimized truncation (EBCOT), and other recently developed "sparse geometric representation" based compression algorithms. The proposed image compression algorithm outperforms the EZW, the Bandelets and the GW algorithm. The presented algorithm reports a gain of 0.22 dB over the GW method at the compression ratio of 64 for the Cameraman test image.
Quantum algorithms for topological and geometric analysis of data.
Lloyd, Seth; Garnerone, Silvano; Zanardi, Paolo
2016-01-25
Extracting useful information from large data sets can be a daunting task. Topological methods for analysing data sets provide a powerful technique for extracting such information. Persistent homology is a sophisticated tool for identifying topological features and for determining how such features persist as the data is viewed at different scales. Here we present quantum machine learning algorithms for calculating Betti numbers--the numbers of connected components, holes and voids--in persistent homology, and for finding eigenvectors and eigenvalues of the combinatorial Laplacian. The algorithms provide an exponential speed-up over the best currently known classical algorithms for topological data analysis.
Quantum algorithms for topological and geometric analysis of data
Lloyd, Seth; Garnerone, Silvano; Zanardi, Paolo
2016-01-01
Extracting useful information from large data sets can be a daunting task. Topological methods for analysing data sets provide a powerful technique for extracting such information. Persistent homology is a sophisticated tool for identifying topological features and for determining how such features persist as the data is viewed at different scales. Here we present quantum machine learning algorithms for calculating Betti numbers—the numbers of connected components, holes and voids—in persistent homology, and for finding eigenvectors and eigenvalues of the combinatorial Laplacian. The algorithms provide an exponential speed-up over the best currently known classical algorithms for topological data analysis. PMID:26806491
Quantum algorithms for topological and geometric analysis of data
2014-01-01
Extracting useful information from large data sets can be a daunting task. Topological methods for analysing data sets provide a powerful technique for extracting such information. Persistent homology is a sophisticated tool for identifying topological features and for determining how such features persist as the data is viewed at different scales. Here we present quantum machine learning algorithms for calculating Betti numbers—the numbers of connected components, holes and voids—in persiste...
Dual geometric worm algorithm for two-dimensional discrete classical lattice models
Hitchcock, Peter; Sørensen, Erik S.; Alet, Fabien
2004-07-01
We present a dual geometrical worm algorithm for two-dimensional Ising models. The existence of such dual algorithms was first pointed out by Prokof’ev and Svistunov [N. Prokof’ev and B. Svistunov, Phys. Rev. Lett. 87, 160601 (2001)]. The algorithm is defined on the dual lattice and is formulated in terms of bond variables and can therefore be generalized to other two-dimensional models that can be formulated in terms of bond variables. We also discuss two related algorithms formulated on the direct lattice, applicable in any dimension. These latter algorithms turn out to be less efficient but of considerable intrinsic interest. We show how such algorithms quite generally can be “directed” by minimizing the probability for the worms to erase themselves. Explicit proofs of detailed balance are given for all the algorithms. In terms of computational efficiency the dual geometrical worm algorithm is comparable to well known cluster algorithms such as the Swendsen-Wang and Wolff algorithms, however, it is quite different in structure and allows for a very simple and efficient implementation. The dual algorithm also allows for a very elegant way of calculating the domain wall free energy.
gpICA: A Novel Nonlinear ICA Algorithm Using Geometric Linearization
Directory of Open Access Journals (Sweden)
Nguyen Thang Viet
2007-01-01
Full Text Available A new geometric approach for nonlinear independent component analysis (ICA is presented in this paper. Nonlinear environment is modeled by the popular post nonlinear (PNL scheme. To eliminate the nonlinearity in the observed signals, a novel linearizing method named as geometric post nonlinear ICA (gpICA is introduced. Thereafter, a basic linear ICA is applied on these linearized signals to estimate the unknown sources. The proposed method is motivated by the fact that in a multidimensional space, a nonlinear mixture is represented by a nonlinear surface while a linear mixture is represented by a plane, a special form of the surface. Therefore, by geometrically transforming the surface representing a nonlinear mixture into a plane, the mixture can be linearized. Through simulations on different data sets, superior performance of gpICA algorithm has been shown with respect to other algorithms.
gpICA: A Novel Nonlinear ICA Algorithm Using Geometric Linearization
Nguyen, Thang Viet; Patra, Jagdish Chandra; Emmanuel, Sabu
2006-12-01
A new geometric approach for nonlinear independent component analysis (ICA) is presented in this paper. Nonlinear environment is modeled by the popular post nonlinear (PNL) scheme. To eliminate the nonlinearity in the observed signals, a novel linearizing method named as geometric post nonlinear ICA (gpICA) is introduced. Thereafter, a basic linear ICA is applied on these linearized signals to estimate the unknown sources. The proposed method is motivated by the fact that in a multidimensional space, a nonlinear mixture is represented by a nonlinear surface while a linear mixture is represented by a plane, a special form of the surface. Therefore, by geometrically transforming the surface representing a nonlinear mixture into a plane, the mixture can be linearized. Through simulations on different data sets, superior performance of gpICA algorithm has been shown with respect to other algorithms.
Numerical nonlinear complex geometrical optics algorithm for the 3D Calderón problem
DEFF Research Database (Denmark)
Delbary, Fabrice; Knudsen, Kim
2014-01-01
computer implementation of the full nonlinear algorithm is given. First a boundary integral equation is solved by a Nystrom method for the traces of the complex geometrical optics solutions, second the scattering transform is computed and inverted using fast Fourier transform, and finally a boundary value...
DEFF Research Database (Denmark)
Endelt, Benny Ørtoft; Volk, Wolfram
2013-01-01
, the reaction speed may be insufficient compared to the production rate in an industrial application. We propose to design an iterative learning control (ILC) algorithm which can control and update the blank-holder force as well as the distribution of the blank-holder force based on limited geometric data from...
Area collapse algorithm computing new curve of 2D geometric objects
Buczek, Michał Mateusz
2017-06-01
The processing of cartographic data demands human involvement. Up-to-date algorithms try to automate a part of this process. The goal is to obtain a digital model, or additional information about shape and topology of input geometric objects. A topological skeleton is one of the most important tools in the branch of science called shape analysis. It represents topological and geometrical characteristics of input data. Its plot depends on using algorithms such as medial axis, skeletonization, erosion, thinning, area collapse and many others. Area collapse, also known as dimension change, replaces input data with lower-dimensional geometric objects like, for example, a polygon with a polygonal chain, a line segment with a point. The goal of this paper is to introduce a new algorithm for the automatic calculation of polygonal chains representing a 2D polygon. The output is entirely contained within the area of the input polygon, and it has a linear plot without branches. The computational process is automatic and repeatable. The requirements of input data are discussed. The author analyzes results based on the method of computing ends of output polygonal chains. Additional methods to improve results are explored. The algorithm was tested on real-world cartographic data received from BDOT/GESUT databases, and on point clouds from laser scanning. An implementation for computing hatching of embankment is described.
Parallel Algorithm of Geometrical Hashing Based on NumPy Package and Processes Pool
Directory of Open Access Journals (Sweden)
Klyachin Vladimir Aleksandrovich
2015-10-01
Full Text Available The article considers the problem of multi-dimensional geometric hashing. The paper describes a mathematical model of geometric hashing and considers an example of its use in localization problems for the point. A method of constructing the corresponding hash matrix by parallel algorithm is considered. In this paper an algorithm of parallel geometric hashing using a development pattern «pool processes» is proposed. The implementation of the algorithm is executed using the Python programming language and NumPy package for manipulating multidimensional data. To implement the process pool it is proposed to use a class Process Pool Executor imported from module concurrent.futures, which is included in the distribution of the interpreter Python since version 3.2. All the solutions are presented in the paper by corresponding UML class diagrams. Designed GeomNash package includes classes Data, Result, GeomHash, Job. The results of the developed program presents the corresponding graphs. Also, the article presents the theoretical justification for the application process pool for the implementation of parallel algorithms. It is obtained condition t2 > (p/(p-1*t1 of the appropriateness of process pool. Here t1 - the time of transmission unit of data between processes, and t2 - the time of processing unit data by one processor.
The Information Is In the Maps: Representations & Algorithms for Mapping among Geometric Data
2015-09-30
of disciplines that use geometric data, has helped generate novel mathematics and algorithms, and has made connections with cognitive science concepts...The goal of this effort has been to develop a set of mathematical and computational tools for describing, analyzing, computing and exploiting... analogy , compression, error correction, and summarization over the data. For example, given a collection of images with shared content across a number
Chen, Qiang; Liu, Jian; Xiao, Jianyuan; Zhang, Ruili; He, Yang; Wang, Yulei
2016-01-01
An infinite dimensional canonical symplectic structure and structure-preserving geometric algorithms are developed for the photon-matter interactions described by the Schr\\"odinger-Maxwell equations. The algorithms preserve the symplectic structure of the system and the unitary nature of the wavefunctions, and bound the energy error of the simulation for all time-steps. This new numerical capability enables us to carry out first-principle based simulation study of important photon-matter interactions, such at the high harmonic generation and stabilization of ionization, with long-term accuracy and fidelity.
Inverse-free Berlekamp-Massey-Sakata Algorithm and Small Decoders for Algebraic-Geometric Codes
Matsui, Hajime
2007-01-01
This paper proposes a novel algorithm for finding error-locators of algebraic-geometric codes that can eliminate the division-calculations of finite fields from the Berlekamp-Massey-Sakata algorithm. This inverse-free algorithm provides full performance in correcting a certain class of errors, generic errors, which includes most errors, and can decode codes on algebraic curves without the determination of unknown syndromes. Moreover, we propose three different kinds of architectures that our algorithm can be applied to, and we represent the control operation of shift-registers and switches at each clock-timing with numerical simulations. We estimate the performance in comparison of the total running time and the numbers of multipliers and shift-registers in three architectures with those of the conventional ones for codes on algebraic curves.
The Geometric Cluster Algorithm: Rejection-Free Monte Carlo Simulation of Complex Fluids
Luijten, Erik
2005-03-01
The study of complex fluids is an area of intense research activity, in which exciting and counter-intuitive behavior continue to be uncovered. Ironically, one of the very factors responsible for such interesting properties, namely the presence of multiple relevant time and length scales, often greatly complicates accurate theoretical calculations and computer simulations that could explain the observations. We have recently developed a new Monte Carlo simulation methodootnotetextJ. Liu and E. Luijten, Phys. Rev. Lett.92, 035504 (2004); see also Physics Today, March 2004, pp. 25--27. that overcomes this problem for several classes of complex fluids. Our approach can accelerate simulations by orders of magnitude by introducing nonlocal, collective moves of the constituents. Strikingly, these cluster Monte Carlo moves are proposed in such a manner that the algorithm is rejection-free. The identification of the clusters is based upon geometric symmetries and can be considered as the off-latice generalization of the widely-used Swendsen--Wang and Wolff algorithms for lattice spin models. While phrased originally for complex fluids that are governed by the Boltzmann distribution, the geometric cluster algorithm can be used to efficiently sample configurations from an arbitrary underlying distribution function and may thus be applied in a variety of other areas. In addition, I will briefly discuss various extensions of the original algorithm, including methods to influence the size of the clusters that are generated and ways to introduce density fluctuations.
A Greedy Algorithm for a Special Class of Geometric Set Covering Problems
DEFF Research Database (Denmark)
Stolpe, Mathias; Bechmann, Andreas
of a geometric set covering problem we propose a greedy type algorithm. We also propose a linear mixed 0 – 1 formulation of the problem. For each problem instance this formulation is solved by a commercial branch-andcut solver and the results are used to validate the quality of the solution from the greedy...... algorithm. The greedy algorithm finds the minimum number of squares for all but one problem instances from a set of 26 representative real-world examples.......We consider the problem of covering a set of given points in the plane by the smallest number of axis aligned squares of a given fixed size. This problem is of importance for computational fluid dynamics simulations of both onshore and offshore wind turbine parks. For this special case...
DEFF Research Database (Denmark)
Endelt, Benny Ørtoft; Volk, Wolfram
2013-01-01
Feedback control of sheet metal forming operations has been an active research field the last two decades and highly advanced control algorithms have been proposed - controlling both the total blank-holder force and in some cases also the distribution of the blank-holder force. However, there is ......Feedback control of sheet metal forming operations has been an active research field the last two decades and highly advanced control algorithms have been proposed - controlling both the total blank-holder force and in some cases also the distribution of the blank-holder force. However......, the reaction speed may be insufficient compared to the production rate in an industrial application. We propose to design an iterative learning control (ILC) algorithm which can control and update the blank-holder force as well as the distribution of the blank-holder force based on limited geometric data from...
Directory of Open Access Journals (Sweden)
Yogeesha C.B
2014-09-01
Full Text Available The classical methods have limited scope in practical applications as some of them involve objective functions which are not continuous and/or differentiable. Evolutionary Computation is a subfield of artificial intelligence that involves combinatorial optimization problems. Travelling Salesperson Problem (TSP, which considered being a classic example for Combinatorial Optimization problem. It is said to be NP-Complete problem that cannot be solved conventionally particularly when number of cities increase. So Evolutionary techniques is the feasible solution to such problem. This paper explores an evolutionary technique: Geometric Hopfield Neural Network model to solve Travelling Salesperson Problem. Paper also achieves the results of Geometric TSP and compares the result with one of the existing widely used nature inspired heuristic approach Ant Colony Optimization Algorithms (ACA/ACO to solve Travelling Salesperson Problem.
Pre-processing Algorithm for Rectification of Geometric Distortions in Satellite Images
Directory of Open Access Journals (Sweden)
Narayan Panigrahi
2011-02-01
Full Text Available A number of algorithms have been reported to process and remove geometric distortions in satellite images. Ortho-correction, geometric error correction, radiometric error removal, etc are a few important examples. These algorithm require supplementary meta-information of the satellite images such as ground control points and correspondence, sensor orientation details, elevation profile of the terrain, etc to establish corresponding transformations. In this paper, a pre-processing algorithm has been proposed which removes systematic distortions of a satellite image and thereby removes the blank portion of the image. It is an input-to-output mapping of image pixels, where the transformation computes the coordinate of each output pixel corresponding to the input pixel of an image. The transformation is established by the exact amount of scaling, rotation and translation needed for each pixel in the input image so that the distortion induced during the recording stage is corrected.Defence Science Journal, 2011, 61(2, pp.174-179, DOI:http://dx.doi.org/10.14429/dsj.61.421
A prefiltered cuckoo search algorithm with geometric operators for solving Sudoku problems.
Soto, Ricardo; Crawford, Broderick; Galleguillos, Cristian; Monfroy, Eric; Paredes, Fernando
2014-01-01
The Sudoku is a famous logic-placement game, originally popularized in Japan and today widely employed as pastime and as testbed for search algorithms. The classic Sudoku consists in filling a 9 × 9 grid, divided into nine 3 × 3 regions, so that each column, row, and region contains different digits from 1 to 9. This game is known to be NP-complete, with existing various complete and incomplete search algorithms able to solve different instances of it. In this paper, we present a new cuckoo search algorithm for solving Sudoku puzzles combining prefiltering phases and geometric operations. The geometric operators allow one to correctly move toward promising regions of the combinatorial space, while the prefiltering phases are able to previously delete from domains the values that do not conduct to any feasible solution. This integration leads to a more efficient domain filtering and as a consequence to a faster solving process. We illustrate encouraging experimental results where our approach noticeably competes with the best approximate methods reported in the literature.
Directory of Open Access Journals (Sweden)
Somar M. Nacy
2009-01-01
Full Text Available Problem statement: One are now interested to investigate the optimum design procedure for a finger driving mechanism to have a good configuration of the finger for its utilization in hand prosthesis. A Geometric Optimization of Three-Phalanx Prosthesis Underactuated Fingers (TPPUF based on a Particle Swarm Optimization (PSO was presented. Approach: Firstly, a numerical evaluation of the human-like motion was obtained by using an anthropomorphic finger mechanism. Secondly, the dimensional design of a finger driving mechanism had been formulated as a multi-objective optimization problem by using evaluation criteria for fundamental characteristics that were associated with finger motion, grasping equilibrium and force transmission. Results: Testing results indicated that the proposed PSO gives high-quality result and shorter computation time compared with genetic algorithm. Conclusion: Using the PSO Algorithm with the Matlab-software, it is possible to identify all the necessary parameters of the mathematical models.
A New Algorithm for Two—Dimensional Line Clipping via Geometric Transformation
Institute of Scientific and Technical Information of China (English)
汪灏泓; 吴瑞迅; 等
1998-01-01
Line segment clipping is a basic operation of the visualization process in computer graphics.So far there exist four computational models for clipping a line segment against a window,(1)the encoding,(2)the parametric,(3)the geometric transforma tion,and (4)the parallel cutting.This paper presents an algorithm that is based on the third method.By making use of symmetric properties of a window and transformation operations,both endpoints of a line segment are transformed,so that the basic cases are reduced into two that can be easily handled,thus the problems in NLN and AS where there are too many sub-procedure calls and basic cases that are difficult to deal with are tackled.Both analytical and experimental results from random input data show that the algorithm is better than other developed ones,in view of the speed and the number of operations.
An Efficient Algorithm for Calculating Aircraft RCS Based on the Geometrical Characteristics
Institute of Scientific and Technical Information of China (English)
Gao Zhenghong; Wang Mingliang
2008-01-01
Taking into account the influences of scatterer geometrical shapes on induced currents, an algorithm, termed the sparse-matrix method (SMM), is proposed to calculate radar cross section (RCS) of aircraft configuration. Based on the geometrical characteristics and the method of moment (MOM), the SMM points out that the strong current coupling zone could be predefined according to the shape of scatterers. Two geometrical parameters, the surface curvature and the electrical space between the field position and source position, are deducted to distinguish the dominant current coupling. Then the strong current coupling is computed to construct an impedance matrix having sparse nature, which is solved to compute RCS. The efficiency and feasibility of the SMM are demonstrated by computing electromagnetic scattering of some kinds of shapes such as a cone-sphere with a gap, a bi-arc column and a stealth aircraft configuration.The numerical results show that: (1) the accuracy of SMM is satisfied, as compared with MOM, and the computational time it spends is only about 8% of the MOM; (2) with the electrical space considered, making another allowance for the surface curvature can reduce the computation time by 9.5%.
Fast and Easy 3D Reconstruction with the Help of Geometric Constraints and Genetic Algorithms
Annich, Afafe; El Abderrahmani, Abdellatif; Satori, Khalid
2017-09-01
The purpose of the work presented in this paper is to describe new method of 3D reconstruction from one or more uncalibrated images. This method is based on two important concepts: geometric constraints and genetic algorithms (GAs). At first, we are going to discuss the combination between bundle adjustment and GAs that we have proposed in order to improve 3D reconstruction efficiency and success. We used GAs in order to improve fitness quality of initial values that are used in the optimization problem. It will increase surely convergence rate. Extracted geometric constraints are used first to obtain an estimated value of focal length that helps us in the initialization step. Matching homologous points and constraints is used to estimate the 3D model. In fact, our new method gives us a lot of advantages: reducing the estimated parameter number in optimization step, decreasing used image number, winning time and stabilizing good quality of 3D results. At the end, without any prior information about our 3D scene, we obtain an accurate calibration of the cameras, and a realistic 3D model that strictly respects the geometric constraints defined before in an easy way. Various data and examples will be used to highlight the efficiency and competitiveness of our present approach.
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Litian Duan
2016-11-01
Full Text Available In the multiple-reader environment (MRE of radio frequency identification (RFID system, multiple readers are often scheduled to interrogate the randomized tags via operating at different time slots or frequency channels to decrease the signal interferences. Based on this, a Geometric Distribution-based Multiple-reader Scheduling Optimization Algorithm using Artificial Immune System (GD-MRSOA-AIS is proposed to fairly and optimally schedule the readers operating from the viewpoint of resource allocations. GD-MRSOA-AIS is composed of two parts, where a geometric distribution function combined with the fairness consideration is first introduced to generate the feasible scheduling schemes for reader operation. After that, artificial immune system (including immune clone, immune mutation and immune suppression quickly optimize these feasible ones as the optimal scheduling scheme to ensure that readers are fairly operating with larger effective interrogation range and lower interferences. Compared with the state-of-the-art algorithm, the simulation results indicate that GD-MRSOA-AIS could efficiently schedules the multiple readers operating with a fairer resource allocation scheme, performing in larger effective interrogation range.
Hadaś, E.; Borkowski, A.; Estornell, J.
2016-06-01
The estimation of dendrometric parameters has become an important issue for the agricultural planning and management. Since the classical field measurements are time consuming and inefficient, Airborne Laser Scanning (ALS) data can be used for this purpose. Point clouds acquired for orchard areas allow to determine orchard structures and geometric parameters of individual trees. In this research we propose an automatic method that allows to determine geometric parameters of individual olive trees using ALS data. The method is based on the α-shape algorithm applied for normalized point clouds. The algorithm returns polygons representing crown shapes. For points located inside each polygon, we select the maximum height and the minimum height and then we estimate the tree height and the crown base height. We use the first two components of the Principal Component Analysis (PCA) as the estimators for crown diameters. The α-shape algorithm requires to define the radius parameter R. In this study we investigated how sensitive are the results to the radius size, by comparing the results obtained with various settings of the R with reference values of estimated parameters from field measurements. Our study area was the olive orchard located in the Castellon Province, Spain. We used a set of ALS data with an average density of 4 points m-2. We noticed, that there was a narrow range of the R parameter, from 0.48 m to 0.80 m, for which all trees were detected and for which we obtained a high correlation coefficient (> 0.9) between estimated and measured values. We compared our estimates with field measurements. The RMSE of differences was 0.8 m for the tree height, 0.5 m for the crown base height, 0.6 m and 0.4 m for the longest and shorter crown diameter, respectively. The accuracy obtained with the method is thus sufficient for agricultural applications.
Building Up the Milky Way's Skeleton
Kohler, Susanna
2016-09-01
A team of scientistshas now uncovered half of theentire skeleton of the Milky Way, using an automated method to identify large filaments of gas and dust hiding between stars in the galactic plane.Galactic distribution of 54 newly discovered filaments, plotted along with colored lines indicating six relevant spiral arms in our galaxy. The upper two plots show the consistency of the filaments motion with the spiral arms, while the lower shows their location within the galactic plane. [Wang et al. 2016]The Search for Nessie and FriendsThe Milky Ways interstellar medium is structured hierarchically into filaments. These structures are difficult to observe since they largely lie in the galactic plane, but if we can discover the distribution and properties of these filaments, we can better understand how our galaxy formed, and how the filaments affect star formation in our galaxy today.Some of the largest of the Milky Ways filaments are hundreds of light-years long like the infrared dark cloud nicknamed Nessie, declared in 2013 to be one of the bones of the Milky Way because of its position along the center of the Scutum-Centaurus spiral arm.Follow-up studies since the discovery of Nessie (like this one, or this) have found a number of additional large-scale filaments, but these studies all use different search methods and selection criteria, and the searches all start with visual inspection by humans to identify candidates.What if we could instead automate the detection process and build a homogeneous sample of the large filaments making up the skeleton of the Milky Way?Automated DetectionThis is exactly what a team of astronomers led by Ke Wang (European Southern Observatory) has done. The group used a customization of an algorithm called a minimum spanning tree the technique used to optimize the cost of internet networks, road networks, and electrical grids in our communities to perform an automated search of data from the Bolocam Galactic Plane Survey. The search was
Metal transfer and build-up in friction and cutting
Kuznetsov, V D
1956-01-01
Metal Transfer and Build-up in Friction and Cutting aims to systematize our knowledge of the metal build-up, to describe some of the investigations past and present carried out in SFTI (Tomsk), and to make an effort to explain a number of the phenomena in cutting, scratching, and sliding from the point of view of metal transfer theory. The book opens with a chapter on the temperature of the rubbing interface of two solids. This temperature is needed in order to elucidate the nature of the formation of a build-up in scratching, cutting, and sliding. Separate chapters follow on the seizure phen
Smoothing Algorithm for Planar and Surface Mesh Based on Element Geometric Deformation
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Shuli Sun
2015-01-01
Full Text Available Smoothing is one of the basic procedures for improvement of mesh quality. In this paper, a novel and efficient smoothing approach for planar and surface mesh based on element geometric deformation is developed. The presented approach involves two main stages. The first stage is geometric deformation of all the individual elements through a specially designed two-step stretching-shrinking operation (SSO, which is performed by moving the vertices of each element according to a certain rule in order to get better shape of the element. The second stage is to determine the position of each node of the mesh by a weighted average strategy according to quality changes of its adjacent elements. The suggested SSO-based smoothing algorithm works efficiently for triangular mesh and can be naturally expanded to quadrilateral mesh, arbitrary polygonal mesh, and mixed mesh. Combined with quadratic error metric (QEM, this approach may be also applied to improve the quality of surface mesh. The proposed method is simple to program and inherently very suitable for parallelization, especially on graphic processing unit (GPU. Results of numerical experiments demonstrate the effectiveness and potential of this method.
Annicchiarico, W
2001-01-01
Structural optimization is an engineering field which deal with the improvement of existing solutions or even more find new solutions that are better than the previous ones under some selected criterion. Shape optimization is a research area in this field and it is involved in developing new methodologies to find better structural design based on the shape as resistant element, as for example solutions with the less stress concentration zones and made with the minimum amount of material. The goal of this doctoral dissertation is to present and discuss a general structural shape optimization methodology able to optimize several structural systems or mechanical devices. The approach presented herein is based on global search optimization tools such as Genetic Algorithms and geometric design elements by means of beta-splines curves and surfaces representation. Finally the great versatility of the developed tool is presented and discussed with an application example.
Helping College Students Build up Confidence in Listening
Institute of Scientific and Technical Information of China (English)
刘鹃
2015-01-01
Listening is the basis of communication,so fostering students’listening ability is very important.Though improving students’listening is very difficult,to help them build up their confidence in listening is an effective way.
Helping College Students Build up Confidence in Listening
Institute of Scientific and Technical Information of China (English)
刘鹃
2015-01-01
Listening is the basis of communication,so fostering students’ listening ability is very important.Though improving students’ listening is very difficult,to help them build up their confidence in listening is an effective way.
Information geometric algorithm for estimating switching probabilities in space-varying HMM.
Nascimento, Jacinto C; Barão, Miguel; Marques, Jorge S; Lemos, João M
2014-12-01
This paper proposes an iterative natural gradient algorithm to perform the optimization of switching probabilities in a space-varying hidden Markov model, in the context of human activity recognition in long-range surveillance. The proposed method is a version of the gradient method, developed under an information geometric viewpoint, where the usual Euclidean metric is replaced by a Riemannian metric on the space of transition probabilities. It is shown that the change in metric provides advantages over more traditional approaches, namely: 1) it turns the original constrained optimization into an unconstrained optimization problem; 2) the optimization behaves asymptotically as a Newton method and yields faster convergence than other methods for the same computational complexity; and 3) the natural gradient vector is an actual contravariant vector on the space of probability distributions for which an interpretation as the steepest descent direction is formally correct. Experiments on synthetic and real-world problems, focused on human activity recognition in long-range surveillance settings, show that the proposed methodology compares favorably with the state-of-the-art algorithms developed for the same purpose.
On Geometric Upper Bounds for Positioning Algorithms in Wireless Sensor Networks
Gholami, Mohammad Reza; Wymeersch, Henk; Rydström, Mats
2012-01-01
This paper studies the possibility of upper bounding the position error of an estimate for range based positioning algorithms in wireless sensor networks. In this study, we argue that in certain situations when the measured distances between sensor nodes are positively biased, e.g., in non-line-of-sight conditions, the target node is confined to a closed bounded convex set (a feasible set) which can be derived from the measurements. Then, we formulate two classes of geometric upper bounds with respect to the feasible set. If an estimate is available, either feasible or infeasible, the worst-case position error can be defined as the maximum distance between the estimate and any point in the feasible set (the first bound). Alternatively, if an estimate given by a positioning algorithm is always feasible, we propose to get the maximum length of the feasible set as the worst-case position error (the second bound). These bounds are formulated as nonconvex optimization problems. To progress, we relax the nonconvex ...
Maric, Tomislav; Bothe, Dieter
2013-01-01
A new parallelized unsplit geometrical Volume of Fluid (VoF) algorithm with support for arbitrary unstructured meshes and dynamic local Adaptive Mesh Refinement (AMR), as well as for two and three dimensional computation is developed. The geometrical VoF algorithm supports arbitrary unstructured meshes in order to enable computations involving flow domains of arbitrary geometrical complexity. The implementation of the method is done within the framework of the OpenFOAM library for Computational Continuum Mechanics (CCM) using the C++ programming language with modern policy based design for high program code modularity. The development of the geometrical VoF algorithm significantly extends the method base of the OpenFOAM library by geometrical volumetric flux computation for two-phase flow simulations. For the volume fraction advection, a novel unsplit geometrical algorithm is developed, which inherently sustains volume conservation utilizing unique Lagrangian discrete trajectories located in the mesh points. ...
An iris localization algorithm based on geometrical features of cow eyes
Zhang, Menglu; Zhao, Lindu; Kong, Qiang
2009-10-01
Abrupt vicious affairs on meat food safety show rapid expansion, which poses a threat to food safety and human health. In order to trace the flow of meat products in the food supply chain, the research on the individual identification of large animals based on iris recognition has very important practical significance. Iris localization is the key step in the iris recognition system, and this paper makes the cow iris as an example to propose two-step localization method on the basis of studying and analyzing lots of cow geometrical features. Firstly, threshold transform and Sobel edge detection operator are used to make the image binarization processing and realize coarse location, and the coordinates of boundary points are determined with the quadratic B-spline interpolation curves. Secondly, the cow eye iris image is located from the coarseness to fine through fitting circles. This paper proposes two methods to determine the parameters of the inner and outer boundary circles, including fitting concentric and non-concentric circle. Experimental results show that fitting non-concentric circle algorithm can locate iris region quickly and efficiently and has better accuracy and good robustness.
Intel Legend and CERN would build up high speed Internet
2002-01-01
Intel, Legend and China Education and Research Network jointly announced on the 25th of April that they will be cooperating with each other to build up the new generation high speed internet, over the next three years (1/2 page).
Directory of Open Access Journals (Sweden)
O. V. Fomin
2013-10-01
Full Text Available Purpose. Presentation of features and example of the use of the offered determination algorithm of optimum geometrical parameters for the components of freight cars on the basis of the generalized mathematical models, which is realized using computer. Methodology. The developed approach to search for optimal geometrical parameters can be described as the determination of optimal decision of the selected set of possible variants. Findings. The presented application example of the offered algorithm proved its operation capacity and efficiency of use. Originality. The determination procedure of optimal geometrical parameters for freight car components on the basis of the generalized mathematical models was formalized in the paper. Practical value. Practical introduction of the research results for universal open cars allows one to reduce container of their design and accordingly to increase the carrying capacity almost by100 kg with the improvement of strength characteristics. Taking into account the mass of their park this will provide a considerable economic effect when producing and operating. The offered approach is oriented to the distribution of the software packages (for example Microsoft Excel, which are used by technical services of the most enterprises, and does not require additional capital investments (acquisitions of the specialized programs and proper technical staff training. This proves the correctness of the research direction. The offered algorithm can be used for the solution of other optimization tasks on the basis of the generalized mathematical models.
Geometric constraint solving with geometric transformation
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
This paper proposes two algorithms for solving geometric constraint systems. The first algorithm is for constrained systems without loops and has linear complexity. The second algorithm can solve constraint systems with loops. The latter algorithm is of quadratic complexity and is complete for constraint problems about simple polygons. The key to it is to combine the idea of graph based methods for geometric constraint solving and geometric transformations coming from rule-based methods.
Qin, Hong
2016-10-01
Littlejohn's introduction of the non-canonical symplectic structure for the gyrocenter dynamics revolutionized plasma kinetic theory. The discovery of the non-canonical symplectic algorithm for gyrocenters initiated the search for symplectic algorithms for the gyrokinetic system. This effort is enforced by the recent discovery of canonical and non-canonical symplectic algorithms for the Vlasov-Maxwell (VM) system. However, symplectic algorithms for the gyrokinetic system remain elusive despite intense effort. In retrospect, the success of the symplectic algorithms for the VM system can be attributed to its global canonicalizability. Darboux's theorem ensures that any symplectic structure is locally canonicalizable, but not necessarily globally. Indeed, Littlejohn's gyrocenter is not globally canonicalizable. In this talk, I will show to construct a different gyrocenter that is globally canonicalizable. It should be a good starting point for developing symplectic algorithms for the gyrokinetic system. Research supported by the U.S. Department of Energy (DE-AC02-09CH11466).
Directory of Open Access Journals (Sweden)
Jin-Young Lee
2015-01-01
Full Text Available This paper presents a study to analyze and modify the Islamic star pattern using digital algorithm, introducing a method to efficiently modify and control classical geometric patterns through experiments and applications of computer algorithms. This will help to overcome the gap between the closeness of classical geometric patterns and the influx of design by digital technology and to lay out a foundation for efficiency and flexibility in developing future designs and material fabrication by promoting better understanding of the various methods for controlling geometric patterns.
Cardot, Hervé; Zitt, Pierre-André
2011-01-01
With the progress of measurement apparatus and the development of automatic sensors it is not unusual anymore to get thousands of samples of observations taking values in high dimension spaces such as functional spaces. In such large samples of high dimensional data, outlying curves may not be uncommon and even a few individuals may corrupt simple statistical indicators such as the mean trajectory. We focus here on the estimation of the geometric median which is a direct generalization of the real median and has nice robustness properties. The geometric median being defined as the minimizer of a simple convex functional that is differentiable everywhere when the distribution has no atoms, it is possible to estimate it with online gradient algorithms. Such algorithms are very fast and can deal with large samples. Furthermore they also can be simply updated when the data arrive sequentially. We state the almost sure consistency and the L2 rates of convergence of the stochastic gradient estimator as well as the ...
Study on geometric approach of SVM algorithm SK algorithm analysis and study%SVM的几何方法——SK类思路的研究
Institute of Scientific and Technical Information of China (English)
常振华; 陈伯成; 李英杰; 刘文煌; 闫学为
2011-01-01
The geometric approach of the Support Vector Machine(SVM) is a kind of geometric way to find the solution to the problem of the SVM algorithm. Based on its geometric characters,the SK(Schlesinger-Kozinec) algorithm is studied intuitively. It briefly sums up the two convex hulls,based on their relative positions, into five categories,and makes sure their optimizing position got in each computing is mostly at the hull vertices or boundary,it can get to the boundary(the optimization place of the computing) at the first computation.The manual single-step simulation results show that the projection is not always successful for such kind of algorithms in many cases,though it can't affect the computing result,but can weaken the algorithm efficiency. Based on the analysis,it demonstrates two improving ways for the soft SK algorithm(Backward-SK and Forward-SK methods),and makes some simulation for comparing. The simulation results show that the improved method computing results are almost same as the SK and soft SK ones,but the computing process of improved one is more intuitive.%支持向量机(Support Vector Machine,SVM)的几何方法是一种基于SVM计算过程中几何意义出发的求解方法.利用其几何特点,比较直观地对其基本算法的构建过程进行了分析.两凸包相对位置可以简要地归纳成5类,且在该类算法迭代过程最优点多在顶点和边界上,该类算法在第一次迭代就可能达到边界(最优点);该类算法的手动单步模拟计结果揭示:很多情况下,该类算法迭代过程的投影并不成功,虽不影响解法的最终结果,但会影响迭代效率:基于几何的分析,给出软SK软算法的两种改进思路(Backward-SK和Forward-SK思路),并进行了仿真比较计算.实验表明,该方法计算效果与原思路相似,但是计算过程理解更加直观.
The Build-Up of Diversity in Complex Ecosystems
Tacchella, Andrea; Gabrielli, Andrea; Pietronero, Luciano
2016-01-01
Diversity is a fundamental feature of ecosystems, even when the concept of ecosystem is extended to sociology or economics. Diversity can be intended as the count of different items, animals, or, more generally, interactions. There are two classes of stylized facts that emerge when diversity is taken into account. The first are Diversity explosions: evolutionary radiations in biology, or the process of escaping 'Poverty Traps' in economics are two well known examples. The second is nestedness: entities with a very diverse set of interactions are the only ones that interact with more specialized ones. In a single sentence: specialists interact with generalists. Nestedness is observed in a variety of bipartite networks of interactions: Biogeographic, macroeconomic and mutualistic to name a few. This indicates that entities diversify following a pattern. Since they appear in such very different systems, these two stylized facts point out that the build up of diversity is driven by a fundamental probabilistic mec...
Electron-Cloud Build-Up: Theory and Data
Energy Technology Data Exchange (ETDEWEB)
Furman, M. A.
2010-10-08
We present a broad-brush survey of the phenomenology, history and importance of the electron-cloud effect (ECE). We briefly discuss the simulation techniques used to quantify the electron-cloud (EC) dynamics. Finally, we present in more detail an effective theory to describe the EC density build-up in terms of a few effective parameters. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire 'ECLOUD' series. In addition, the proceedings of the various flavors of Particle Accelerator Conferences contain a large number of EC-related publications. The ICFA Beam Dynamics Newsletter series contains one dedicated issue, and several occasional articles, on EC. An extensive reference database is the LHC website on EC.
Education, ethics and democracy: philosophical considerations around citizenship building up
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Nelson Orlando Vargas Montañez
2012-06-01
Full Text Available This article aims at showing the analysis of society from a philosophical perspective and the contributions of the Illustration around education, ethics and politics. Taking into account hermeneutics and history, it pretends to highlight the individual’s autonomous learning and the critical pedagogy as means to abolish an authoritarian system in order to give way to an emancipating pedagogy. Besides, philosophical considerations such as education, ethics and democracy are remarked in order to reflect on education as a determining stuff of the individual’s development because it is focused on educating upstanding human beings for the social and political life, able to build up a fair society framed by principles like freedom, security and justice.
Adaptation Algorithm of Geometric Graphs for Robot Motion Planning in Dynamic Environments
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Jae-Han Park
2016-01-01
Full Text Available This study proposes an adaptive graph algorithm for collision-free motion planning of articulated robots in dynamic environments. For this purpose, deformations of the configuration space were analyzed according to the changes of the workspace using various simulations. Subsequently, we adopted the principles of gas motion dynamics in our adaptation algorithm to address the issue of the deformation of the configuration space. The proposed algorithm has an adaptation mechanism based on expansive repulsion and sensory repulsion, and it can be performed to provide the entire adaptation using distributed processing. The simulation results confirmed that the proposed method allows the adaptation of the roadmap graph to changes of the configuration space.
Closed form and geometric algorithms for real-time control of an avatar
Energy Technology Data Exchange (ETDEWEB)
Semwall, S.K.; Hightower, R.; Stansfield, S.
1995-12-31
In a virtual environment with multiple participants, it is necessary that the user`s actions be replicated by synthetic human forms. Whole body digitizers would be the most realistic solution for capturing the individual participant`s human form, however the best of the digitizers available are not interactive and are therefore not suitable for real-time interaction. Usually, a limited number of sensors are used as constraints on the synthetic human form. Inverse kinematics algorithms are applied to satisfy these sensor constraints. These algorithms result in slower interaction because of their iterative nature, especially when there are a large number of participants. To support real-time interaction in a virtual environment, there is a need to generate closed for solutions and fast searching algorithms. In this paper, a new closed form solution for the arms (and legs) is developed using two magnetic sensors. In developing this solution, we use the biomechanical relationship between the lower arm and the upper arm to provide an analytical, non-iterative solution, We have also outlined a solution for the whole human body by using up to ten magnetic sensors to break the human skeleton into smaller kinematic chains. In developing our algorithms, we use the knowledge of natural body postures to generate faster solutions for real-time interaction.
Quiet Spike Build-Up Ground Vibration Testing Approach
Spivey, Natalie D.; Herrera, Claudia Y.; Truax, Roger; Pak, Chan-gi; Freund, Donald
2007-01-01
NASA's Dryden Flight Research Center uses a modified F-15B (836) aircraft as a testbed for a variety of flight research:experiments mounted underneath the aircraft fuselage. The F-15B was selected to fly Gulfstream Aerospace Corporation's (GAC)QuietSpike(TM)(QS) project; however, this experiment is very unique and unlike any of the previous testbed experiments flown on the F-15B. It involves the addition of a relatively long quiet spike boom attached to the radar bulkhead of the aircraft. This QS experiment is a stepping stone to airframe structural morphing technologies designed to mitigate sonic born strength of business jets over land. The QS boom is a concept in Which an aircraft's front-end would be extended prior to supersonic acceleration. This morphing would effectively lengthen the aircraft, reducing peak sonic boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, non-coalescing shocklets. Prior to flying the Quietspike(TM) experiment on the F-15B aircraft several ground vibration tests (GVT) were required in order to understand the QS modal characteristics and coupling effects with the F-15B. However, due to the project's late hardware delivery of the QS and the intense schedule, a "traditional" GVT of the mated F-1513 Quietspike(tm) ready-for-flight configuration would not have left sufficient time available for the finite element model update and flutter analyses before flight testing. Therefore, a "nontraditional" ground vibration testing approach was taken. The objective of the QuietSpike (TM) build-up ground testing approach was to ultimately obtain confidence in the F-15B Quietspike(TM) finite element model (FEM) to be used for the flutter analysis. In order to obtain the F15B QS FEM with reliable foundation stiffness between the QS and the F-15B radar bulkhead as well as QS modal characteristics, several different GVT configurations were performed. EAch of the four GVT's performed had a
2013-01-01
Geometric progression (GP) method was utilized to investigate gamma-ray exposure build-up factors of fly-ash bricks for energies from 0.015 to 15 MeV up to 40 mfp penetration depth. The EBFs of the fly-ash bricks are dependent upon the photon energy, penetration depths, and the chemical compositions of the elements. Appreciable variations in exposure build-up factor (EBF) are noted for the fly-ash bricks. The EBFs were found to be small in low and high photon energy regions whereas very large...
Building up and breaking down: mechanisms controlling recombination during replication.
Branzei, Dana; Szakal, Barnabas
2017-08-01
The complete and faithful duplication of the genome is an essential prerequisite for proliferating cells to maintain genome integrity. This objective is greatly challenged by DNA damage encountered during replication, which causes fork stalling and in certain cases, fork breakage. DNA damage tolerance (DDT) pathways mitigate the effects on fork stability induced by replication fork stalling by mediating damage-bypass and replication fork restart. These DDT mechanisms, largely relying on homologous recombination (HR) and specialized polymerases, can however contribute to genome rearrangements and mutagenesis. There is a profound connection between replication and recombination: recombination proteins protect replication forks from nuclease-mediated degradation of the nascent DNA strands and facilitate replication completion in cells challenged by DNA damage. Moreover, in case of fork collapse and formation of double strand breaks (DSBs), the recombination factors present or recruited to the fork facilitate HR-mediated DSB repair, which is primarily error-free. Disruption of HR is inexorably linked to genome instability, but the premature activation of HR during replication often leads to genome rearrangements. Faithful replication necessitates the downregulation of HR and disruption of active RAD51 filaments at replication forks, but upon persistent fork stalling, building up of HR is critical for the reorganization of the replication fork and for filling-in of the gaps associated with discontinuous replication induced by DNA lesions. Here we summarize and reflect on our understanding of the mechanisms that either suppress recombination or locally enhance it during replication, and the principles that underlie this regulation.
Directory of Open Access Journals (Sweden)
N. Jafferi
2009-09-01
Full Text Available This paper focuses on the geometrical design of active noise control (ANC in free- field propagation medium. The development and performance assessment uses genetic optimisation techniques to arrange system components so as to satisfy several performance requirements, such as physical extent of cancellation, controller design restriction and system stability. The ANC system design can be effectively addressed if it is considered as multi – objective optimisation problems. The multi-objective genetic algorithms (MOGAs are well suited to the design of an ANC system and the approach used for it is based on a multi - objective method, with which the physical extent of cancellation and relative stability assessment are dealt with simultaneously.
Keshavarz, M; Mojra, A
2015-05-01
Geometrical features of a cancerous tumor embedded in biological soft tissue, including tumor size and depth, are a necessity in the follow-up procedure and making suitable therapeutic decisions. In this paper, a new socio-politically motivated global search strategy which is called imperialist competitive algorithm (ICA) is implemented to train a feed forward neural network (FFNN) to estimate the tumor's geometrical characteristics (FFNNICA). First, a viscoelastic model of liver tissue is constructed by using a series of in vitro uniaxial and relaxation test data. Then, 163 samples of the tissue including a tumor with different depths and diameters are generated by making use of PYTHON programming to link the ABAQUS and MATLAB together. Next, the samples are divided into 123 samples as training dataset and 40 samples as testing dataset. Training inputs of the network are mechanical parameters extracted from palpation of the tissue through a developing noninvasive technology called artificial tactile sensing (ATS). Last, to evaluate the FFNNICA performance, outputs of the network including tumor's depth and diameter are compared with desired values for both training and testing datasets. Deviations of the outputs from desired values are calculated by a regression analysis. Statistical analysis is also performed by measuring Root Mean Square Error (RMSE) and Efficiency (E). RMSE in diameter and depth estimations are 0.50 mm and 1.49, respectively, for the testing dataset. Results affirm that the proposed optimization algorithm for training neural network can be useful to characterize soft tissue tumors accurately by employing an artificial palpation approach. Copyright © 2015 John Wiley & Sons, Ltd.
Le-Duc, Thang; Ho-Huu, Vinh; Nguyen-Thoi, Trung; Nguyen-Quoc, Hung
2016-12-01
In recent years, various types of magnetorheological brakes (MRBs) have been proposed and optimized by different optimization algorithms that are integrated in commercial software such as ANSYS and Comsol Multiphysics. However, many of these optimization algorithms often possess some noteworthy shortcomings such as the trap of solutions at local extremes, or the limited number of design variables or the difficulty of dealing with discrete design variables. Thus, to overcome these limitations and develop an efficient computation tool for optimal design of the MRBs, an optimization procedure that combines differential evolution (DE), a gradient-free global optimization method with finite element analysis (FEA) is proposed in this paper. The proposed approach is then applied to the optimal design of MRBs with different configurations including conventional MRBs and MRBs with coils placed on the side housings. Moreover, to approach a real-life design, some necessary design variables of MRBs are considered as discrete variables in the optimization process. The obtained optimal design results are compared with those of available optimal designs in the literature. The results reveal that the proposed method outperforms some traditional approaches.
Rodis, Panteleimon
2011-01-01
The topic of this paper is to present a study of the connection errors in networks of linear features that are mapped in Geographical Information Systems (GIS), as well as algorithms that detect them and the notion of geometrical reduction and its use in spatial data algorithms. In datasets of networks usually there can be found errors, when a number of elements of the network are not connected according to the specifications of the network. This can occur due to errors in the digitization process of the network or because these elements are connected in reality in a not legal way. These errors can be topological, when the network elements are not correctly connected, or errors that violate the specifications of the network. Examples of specifications that their violation can result this situation is when in a telecommunication network there is the restriction that channels of high capacity should not be connected directly to home networks but only through local sub-networks, or when in a road network there i...
Should we trust build-up/wash-off water quality models at the scale of urban catchments?
Bonhomme, Céline; Petrucci, Guido
2017-01-01
Models of runoff water quality at the scale of an urban catchment usually rely on build-up/wash-off formulations obtained through small-scale experiments. Often, the physical interpretation of the model parameters, valid at the small-scale, is transposed to large-scale applications. Testing different levels of spatial variability, the parameter distributions of a water quality model are obtained in this paper through a Monte Carlo Markov Chain algorithm and analyzed. The simulated variable is the total suspended solid concentration at the outlet of a periurban catchment in the Paris region (2.3 km(2)), for which high-frequency turbidity measurements are available. This application suggests that build-up/wash-off models applied at the catchment-scale do not maintain their physical meaning, but should be considered as "black-box" models. Copyright Â© 2016 Elsevier Ltd. All rights reserved.
Contribution of school to building up the partnership with parents
Directory of Open Access Journals (Sweden)
Polovina Nada
2008-01-01
Full Text Available This paper studies the way in which headmasters and class masters perceive and estimate the factors, obstacles and incentives to building up a partnership between school and parents. The sample consists of 60 headmasters and 305 class masters from 60 schools (37 urban and 23 rural in Serbia. Headmasters and teachers filled in separate, but parallel questionnaires (modified only in the segment of different roles that were created for the purposes of research. Questionnaire items inquire about the factors contributing to the inclusion of parents, the obstacles in developing the cooperation between parents and school and the peculiarities of school environment that can contribute to the development of that cooperation, as well as about the peculiarities of the communication with parents. Research findings indicate that headmasters and teachers assess the importance of different components in the field of cooperation with parents in a similar, but not identical way. Most similarities are found in the perception of obstacles for establishing cooperation (the problems of coordinating time periods for meetings, previous bad experiences of parents regarding cooperation. The majority of differences lie in perceiving the importance of cooperation factors (headmasters emphasise the "parent factor", while teachers do so both for the "parent factor" and "child factor", as well as in perceiving the necessary incentives for the improvement of cooperation between school and parents (headmasters emphasise the spatial-temporal organization components, and teachers do so for spatial components and personal initiatives. In the assessments of both the headmasters and teachers we obtained differences marked by gender, the longitude of years of service, size of the settlement where the school is located (town-village. The general conclusion indicates that the topic of cooperation between school and parents is highly and in many ways context sensitive, and that the
Seafloor geodesy: Measuring surface deformation and strain-build up
Kopp, Heidrun; Lange, Dietrich; Hannemann, Katrin; Petersen, Florian
2017-04-01
Seafloor deformation is intrinsically related to tectonic processes, which potentially may evolve into geohazards, including earthquakes and tsunamis. The nascent scientific field of seafloor geodesy provides a way to monitor crustal deformation at high resolution comparable to the satellite-based GPS technique upon which terrestrial geodesy is largely based. The measurements extract information on stress and elastic strain stored in the oceanic crust. Horizontal seafloor displacement can be obtained by acoustic/GPS combination to provide absolute positioning or by long-term acoustic telemetry between different beacons fixed on the seafloor. The GeoSEA (Geodetic Earthquake Observatory on the SEAfloor) array uses acoustic telemetry for relative positioning at mm-scale resolution. The transponders within an array intercommunicate via acoustic signals for a period of up to 3.5 years. The seafloor acoustic transponders are mounted on 4 m high tripod steel frames to ensure clear line-of-sight between the stations. The transponders also include high-precision pressure sensors to monitor vertical movements and dual-axis inclinometers in order to measure their level as well as any tilt of the seafloor. Sound velocity sensor measurements are used to correct for water sound speed variations. A further component of the network is GeoSURF, a self-steering autonomous surface vehicle (Wave Glider), which monitors system health and is able to upload the seafloor data to the sea surface and to transfer it via satellite. The GeoSEA array is capable of both continuously monitoring horizontal and vertical ground displacement rates along submarine fault zones and characterizing their behavior (locked or aseismically creeping). Seafloor transponders are currently installed along the Siliviri segment of the North Anatolian Fault offshore Istanbul for measurements of strain build-up along the fault. The first 18 month of baseline ranging were analyzed by a joint-least square inversion
Institute of Scientific and Technical Information of China (English)
李宝; 周林芳; 肖国镇
1999-01-01
For a class of algebraic-geometric codes, a type of recurring relation is introduced on the syndrome sequence of an error vector. Then, a new majority yoting scheme is developed. By applying the generalized Berlekamp-Massey algorithm, and incorporating the majority voting scheme, an efficient decoding algorithm up to half the Feng-Rao bound is developed for a class of algebraic-geometric codes, the complexity of which is O （ γo1n2）, where n is the code length, and γ is the genus of curve. On different algebraic curves, the complexity of the algorithm can be lowered by choosing base functions suitably. For example, on Hermitian curves the complexity is O(n7/3.
Taxonomy of factors which influence heavy metal build-up on urban road surfaces.
Liu, An; Gunawardana, Chandima; Gunawardena, Janaka; Egodawatta, Prasanna; Ayoko, Godwin A; Goonetilleke, Ashantha
2016-06-01
Heavy metals build-up on urban road surfaces is a complex process and influenced by a diverse range of factors. Although numerous research studies have been conducted in the area of heavy metals build-up, limited research has been undertaken to rank these factors in terms of their influence on the build-up process. This results in limitations in the identification of the most critical factor/s for accurately estimating heavy metal loads and for designing effective stormwater treatment measures. The research study undertook an in-depth analysis of the factors which influence heavy metals build-up based on data generated from a number of different geographical locations around the world. Traffic volume was found to be the highest ranked factor in terms of influencing heavy metals build-up while land use was ranked the second. Proximity to arterial roads, antecedent dry days and road surface roughness has a relatively lower ranking. Furthermore, the study outcomes advances the conceptual understanding of heavy metals build-up based on the finding that with increasing traffic volume, total heavy metal build-up load increases while the variability decreases. The outcomes from this research study are expected to contribute to more accurate estimation of heavy metals build-up loads leading to more effective stormwater treatment design.
Energy Technology Data Exchange (ETDEWEB)
Wokoma, S; Yoon, J; Jung, J [East Carolina University, Greenville, NC (United States); Lee, S [Rhode Island Hospital / Warren Alpert Medical, Providence, RI (United States)
2014-06-01
Purpose: To investigate the impact of custom-made build-up caps for a diode detector in robotic radiosurgery radiation fields with variable collimator (IRIS) for collimator scatter factor (Sc) calculation. Methods: An acrylic cap was custom-made to fit our SFD (IBA Dosimetry, Germany) diode detector. The cap has thickness of 5 cm, corresponding to a depth beyond electron contamination. IAEA phase space data was used for beam modeling and DOSRZnrc code was used to model the detector. The detector was positioned at 80 cm source-to-detector distance. Calculations were performed with the SFD, with and without the build-up cap, for clinical IRIS settings ranging from 7.5 to 60 mm. Results: The collimator scatter factors were calculated with and without 5 cm build-up cap. They were agreed within 3% difference except 15 mm cone. The Sc factor for 15 mm cone without buildup was 13.2% lower than that with buildup. Conclusion: Sc data is a critical component in advanced algorithms for treatment planning in order to calculate the dose accurately. After incorporating build-up cap, we discovered differences of up to 13.2 % in Sc factors in the SFD detector, when compared against in-air measurements without build-up caps.
1985-07-26
taatprsenedanIninti~9 on to algorithm and data structures of general interest T. Ottmann introduced the field ofAcomputational geometry;wIth a talk on geometric...to Algorithms and Data Structures, II; Tuesday: 9. 00 - 11. 00 T. Ottmann : Geometric Algorithms in the Plane, I; 11. 30 - 12. 30 F. Luccio: Visibility... OTTMANN Thomas, Professor Universit4t Karlsruhe Inst. f . Angewandte In f rinat i k Postfach h390 7519 Karlsruhe Western Germany PREPARATA Franco
De Puysseleyr, Annemieke; Lechner, Wolfgang; De Neve, Wilfried; Georg, Dietmar; De Wagter, Carlos
2016-06-01
This study evaluated absorbed dose measurements in the build-up region of conventional (FF) versus flattening filter-free (FFF) photon beams. The absorbed dose in the build-up region of static 6 and 10MV FF and FFF beams was measured using radiochromic film and extrapolation chamber dosimetry for single beams with a variety of field sizes, shapes and positions relative to the central axis. Removing the flattening filter generally resulted in slightly higher relative build-up doses. No considerable impact on the depth of maximum dose was found. Copyright © 2016. Published by Elsevier GmbH.
National Research Council Canada - National Science Library
Duhan, Himanshu; Pandit, Inder Kumar; Srivastava, Nikhil; Gugnani, Neeraj; Gupta, Monika; Kochhar, Gulsheen Kaur
2015-01-01
This study was designed to compare the clinical performance of composite, strip crowns, biological restoration, and composite with stainless steel band when used for the coronal build-up of anterior teeth...
Analysis of the build-up of semi and non volatile organic compounds on urban roads.
Mahbub, Parvez; Ayoko, Godwin A; Goonetilleke, Ashantha; Egodawatta, Prasanna
2011-04-01
Vehicular traffic in urban areas may adversely affect urban water quality through the build-up of traffic generated semi and non volatile organic compounds (SVOCs and NVOCs) on road surfaces. The characterisation of the build-up processes is the key to developing mitigation measures for the removal of such pollutants from urban stormwater. An in-depth analysis of the build-up of SVOCs and NVOCs was undertaken in the Gold Coast region in Australia. Principal Component Analysis (PCA) and Multicriteria Decision tools such as PROMETHEE and GAIA were employed to understand the SVOC and NVOC build-up under combined traffic scenarios of low, moderate, and high traffic in different land uses. It was found that congestion in the commercial areas and use of lubricants and motor oils in the industrial areas were the main sources of SVOCs and NVOCs on urban roads, respectively. The contribution from residential areas to the build-up of such pollutants was hardly noticeable. It was also revealed through this investigation that the target SVOCs and NVOCs were mainly attached to particulate fractions of 75-300 μm whilst the redistribution of coarse fractions due to vehicle activity mainly occurred in the >300 μm size range. Lastly, under combined traffic scenario, moderate traffic with average daily traffic ranging from 2300 to 5900 and average congestion of 0.47 were found to dominate SVOC and NVOC build-up on roads.
Ranking the factors influencing polycyclic aromatic hydrocarbons (PAHs) build-up on urban roads.
Liu, An; Ma, Yukun; Deilami, Kaveh; Egodawatta, Prasanna; Goonetilleke, Ashantha
2017-05-01
An in-depth understanding of polycyclic aromatic hydrocarbons (PAHs) build-up on urban roads is essential for effective stormwater treatment design. Past research studies have pointed out the relationship between influential factors and PAHs build-up individually. However, these studies do not provide a comprehensive analysis of the relationships and the hierarchy of factors in terms of their importance in influencing PAHs build-up. This paper presents the outcomes of an in-depth investigation into the range of influential factors, including traffic volume, land use, distance to highway and roughness of road surfaces by ranking them in terms of their influence on PAHs build-up. A number of data analysis techniques including forward stepwise linear regression (FSWLR), principal component analysis (PCA) and multiple linear regression (MLR) were employed for the analyses undertaken. The outcomes confirmed that traffic volume is ranked first while land use and roughness of road surfaces are second and the third, respectively. Distance to highway did not show a significant influence on PAHs build-up. Additionally, it was noted that a high traffic volume tended to produce high loads of PAHs with more than 4 rings and the spatial variability of PAHs build-up were relatively higher in high traffic volume areas. These outcomes contributed to the formulation of a robust stormwater treatment strategy and generation of priority area maps focusing on the removal of PAHs.
Characterizing heavy metal build-up on urban road surfaces: Implication for stormwater reuse
Energy Technology Data Exchange (ETDEWEB)
Liu, An [Research Centre of Environmental Engineering and Management, Graduate School at Shenzhen, Tsinghua University, 518055 Shenzhen (China); Cooperative Research and Education Centre for Environmental Technology, Kyoto University–Tsinghua University, 518055 Shenzhen (China); Liu, Liang; Li, Dunzhu [Research Centre of Environmental Engineering and Management, Graduate School at Shenzhen, Tsinghua University, 518055 Shenzhen (China); Guan, Yuntao, E-mail: guanyt@tsinghua.edu.cn [Research Centre of Environmental Engineering and Management, Graduate School at Shenzhen, Tsinghua University, 518055 Shenzhen (China); School of Environment, Tsinghua University, Beijing 100084 (China)
2015-05-15
Stormwater reuse is increasingly popular in the worldwide. In terms of urban road stormwater, it commonly contains toxic pollutants such as heavy metals, which could undermine the reuse safety. The research study investigated heavy metal build-up characteristics on urban roads in a typical megacity of South China. The research outcomes show the high variability in heavy metal build-up loads among different urban road sites. The degree of traffic congestion and road surface roughness was found to exert a more significant influence on heavy metal build-up rather than traffic volume. Due to relatively higher heavy metal loads, stormwater from roads with more congested traffic conditions or rougher surfaces might be suitable for low-water-quality required activities while the stormwater from by-pass road sections could be appropriate for relatively high-water-quality required purposes since the stormwater could be relatively less polluted. Based on the research outcomes, a decision-making process for heavy metals based urban road stormwater reuse was proposed. The new finding highlights the importance to undertaking a “fit-for-purpose” road stormwater reuse strategy. Additionally, the research results can also contribute to enhancing stormwater reuse safety. - Highlights: • Heavy metal (HM) build-up varies with traffic and road surface conditions. • Traffic congestion and surface roughness exert a higher impact on HM build-up. • A “fit-for-purpose” strategy could suit urban road stormwater reuse.
Build-up of actinides in irradiated fuel rods of the ET-RR-1 reactor
Energy Technology Data Exchange (ETDEWEB)
Adib, M.; Naguib, K.; Morcos, H.N
2001-09-01
The content concentrations of actinides are calculated as a function of operating reactor regime and cooling time at different percentage of fuel burn-up. The build-up transmutation equations of actinides content in an irradiated fuel are solved numerically .A computer code BAC was written to operate on a PC computer to provide the required calculations. The fuel element of 10% {sup 235}U enrichment of ET-RR-1 reactor was taken as an example for calculations using the BAC code. The results are compared with other calculations for the ET-RR-1 fuel rod. An estimation of fissile build-up content of a proposed new fuel of 20% {sup 235}U enrichment for ET-RR-1 reactor is given. The sensitivity coefficients of build-up plutonium concentrations as a function of cross-section data uncertainties are also calculated.
QR码图像几何校正算法的研究%Research on QR code images geometric rectification algorithm
Institute of Scientific and Technical Information of China (English)
黄珂; 薛月菊; 陈瑶; 陈汉鸣; 李鸿生
2014-01-01
When QR code images are filmed by the camera, the deviation of shooting angle will cause the collected QR code images generate geometric distortion and bring difficulties to QR code recognition. Local threshold method and mathe-matical morphology are used to binarize the collected QR code images which appears uneven illumination. Harris corner detection algorithm and convex hull algorithm are combined to find the outline of the QR code and the point on the out-line, using corner detection algorithm of this paper to find the corner of QR code. Finally, using perspective transformation algorithm to recover the distorted image, the results show that this method is effective to solve the problem of geometric distortion of the QR code.%用摄像机拍摄QR码图像时，由于拍摄角度的偏差，可能造成所采集到的QR码图像产生几何失真的情况，给QR码的识别带来了困难。对拍摄到的QR码图像进行预处理，把采集到的光照不均匀的QR码图像采用局部阈值法和数学形态学的方法进行二值化。通过Harris角点检测算法和凸包算法相结合找到QR码的轮廓以及轮廓上的点，再利用该角点检测算法找到QR码的角点，最后使用透视变化法对畸变图像进行恢复。实验结果证明，该方法有效解决了QR码的几何失真问题。
Directory of Open Access Journals (Sweden)
Francisco Casesnoves
2014-08-01
Full Text Available Purpose: Static wedge filters (WF are commonly used in radiation therapy, forward and/or inverse planning. We calculated the exact 2D/3D geometrical pathway of the photon-beam through the usual alloy WF, in order to get a better dose related to the beam intensity attenuation factor(s, after the beam has passed through the WF. The objective was to provide general formulation into the Anisotropic Analytical Algorithm (AAA model coordinates system (depending on collimator/wedge angles that also can be applied to other models. Additionally, second purpose of this study was to develop integral formulation for 3D wedge exponential factor with statistical approximations, with introduction for the limit angle/conformal wedge.Methods: The radiotherapy model used to develop this mathematical task is the classical superposition-convolution algorithm, AAA (developed by Ulmer and Harder. We worked with optimal geometrical approximations to make the computational IMRT calculations quicker/reduce the planning-system time. Analytic geometry/computational-techniques to carry out simulations (for standard wedges are detailed/developed sharply. Integral developments/integral-statistical approximations are explained. Beam-divergence limit Angle for optimal wedge filtration formulas is calculated/sketched, with geometrical approximations. Fundamental trigonometry is used for this purpose.Results: Extent simulation tables for WF of 15º, 30º, 45º, and 60º are shown with errors. As a result, it is possible to determine the best individual treatment dose distribution for each patient. We presented these basic simulations/numerical examples for standard manufacturing WF of straight sloping surface, to check the accuracy/errors of the calculations. Simulations results give low RMS/Relative Error values (formulated for WF of 15º, 30º, 45º, and 60º.Conclusion: We obtained a series of formulas of analytic geometry for WF that can be applied for any particular dose
Feng, Kaiqiang; Li, Jie; Zhang, Xiaoming; Shen, Chong; Bi, Yu; Zheng, Tao; Liu, Jun
2017-09-19
In order to reduce the computational complexity, and improve the pitch/roll estimation accuracy of the low-cost attitude heading reference system (AHRS) under conditions of magnetic-distortion, a novel linear Kalman filter, suitable for nonlinear attitude estimation, is proposed in this paper. The new algorithm is the combination of two-step geometrically-intuitive correction (TGIC) and the Kalman filter. In the proposed algorithm, the sequential two-step geometrically-intuitive correction scheme is used to make the current estimation of pitch/roll immune to magnetic distortion. Meanwhile, the TGIC produces a computed quaternion input for the Kalman filter, which avoids the linearization error of measurement equations and reduces the computational complexity. Several experiments have been carried out to validate the performance of the filter design. The results demonstrate that the mean time consumption and the root mean square error (RMSE) of pitch/roll estimation under magnetic disturbances are reduced by 45.9% and 33.8%, respectively, when compared with a standard filter. In addition, the proposed filter is applicable for attitude estimation under various dynamic conditions.
Space charge build-up in XLPE-cable with temperature gradient
DEFF Research Database (Denmark)
Holbøll, Joachim; Henriksen, Mogens; Hjerrild, Jesper
2000-01-01
Space charge build-up in standard XLPE insulated AC cables has been studied under varying temperature and field conditions. The cables were triple-extruded with the inner semicon on a solid aluminum conductor, 5.5mm XLPE-insulation and an outer semicon. The cables were stressed up to 15kV/mm DC...
How the Build Up of Aqueous Humor Can Damage the Optic Nerve
... Twitter Google Plus Email Print this page How the Build Up of Aqueous Humor Can Damage the Optic Nerve Most, but not all, forms of ... name. Phone (office) Sign Up Join us in the fight to end brain and eye disease 3 ...
How the Build Up of Aqueous Humor Can Damage the Optic Nerve
... Aqueous Humor Can Damage the Optic Nerve How the Build Up of Aqueous Humor Can Damage the Optic Nerve Most, but not all, forms of ... name. Phone (office) Sign Up Join us in the fight to end brain and eye disease 3 ...
Geometric Computing Based on Computerized Descriptive Geometric
Institute of Scientific and Technical Information of China (English)
YU Hai-yan; HE Yuan-Jun
2011-01-01
Computer-aided Design （CAD）, video games and other computer graphic related technology evolves substantial processing to geometric elements. A novel geometric computing method is proposed with the integration of descriptive geometry, math and computer algorithm. Firstly, geometric elements in general position are transformed to a special position in new coordinate system. Then a 3D problem is projected to new coordinate planes. Finally, according to 2D/3D correspondence principle in descriptive geometry, the solution is constructed computerized drawing process with ruler and compasses. In order to make this method a regular operation, a two-level pattern is established. Basic Layer is a set algebraic packaged function including about ten Primary Geometric Functions （PGF） and one projection transformation. In Application Layer, a proper coordinate is established and a sequence of PGFs is sought for to get the final results. Examples illustrate the advantages of our method on dimension reduction, regulatory and visual computing and robustness.
Analysis of build-up of heavy metals and volatile organics on urban roads in gold coast, Australia.
Mahbub, Parvez; Goonetilleke, Ashantha; Ayoko, Godwin A; Egodawatta, Prasanna; Yigitcanlar, Tan
2011-01-01
Urban water quality can be significantly impaired by the build-up of pollutants such as heavy metals and volatile organics on urban road surfaces due to vehicular traffic. Any control strategy for the mitigation of traffic related build-up of heavy metals and volatile organic pollutants should be based on the knowledge of their build-up processes. In the study discussed in this paper, the outcomes of a detailed experimental investigation into build-up processes of heavy metals and volatile organics are presented. It was found that traffic parameters such as average daily traffic, volume over capacity ratio and surface texture depth had similar strong correlations with the build-up of heavy metals and volatile organics. Multicriteria decision analyses revealed that that the 1-74 microm particulate fraction of total suspended solids (TSS) could be regarded as a surrogate indicator for particulate heavy metals in build-up and this same fraction of total organic carbon could be regarded as a surrogate indicator for particulate volatile organics build-up. In terms of pollutants affinity, TSS was found to be the predominant parameter for particulate heavy metals build-up and total dissolved solids was found to be the predominant parameter for the potential dissolved particulate fraction in heavy metals buildup. It was also found that land use did not play a significant role in the build-up of traffic generated heavy metals and volatile organics.
Monitoring the stress build-up in dental cements: a novel optical characterization technique
Ottevaere, Heidi; Tabak, M.; Bartholomees, F.; de Wilde, Willy P.; Veretennicoff, Irina P.; Thienpont, Hugo
2001-01-01
It is well known that during the curing of dental cements, polymerization shrinkage induces unacceptable stresses, which can result into cracks and an over-sensitivity of the teeth. We demonstrate that polarimetric optical fiber sensors can be used to characterize this shrinkage quantitatively. To determine the time evolution and the amount of shrinkage we embed a highly birefringent optical fiber in the dental cement and analyze the change in optical polarization at its output. This change is a measure for the dynamic stress-build up. We also demonstrate the repeatability of our characterization method for these cements. Moreover we given indications that this technique allows for in- vivo monitoring of the stress build-up dynamics between dentine and porcelain facings. This may bring durable all-ceramic restorations closer to reality. In this paper we present the principle of this original optical fiber sensor, its practical implementation and the experimental results we obtained for this application.
BCB Polymer Dielectrics for Electronic Packaging and Build-up Board Applications
Energy Technology Data Exchange (ETDEWEB)
Im, J.H. [Advanced Electronic Materials, Midland (United States); Garrou, P.; Yang, J. [Dow Chemical USA at MCNC (United States); Kaoru, O.; Kohno, M. [Dow Chemical Japan at Gotemba, Shizuoda (Japan); Jung, M.S. [Dow Chemical Korea, Seoul (Korea)
2000-04-24
Dielectric polymer films produced from benzocyclobutene (BCB) formulations (CYCLOTENE family resins) are known to possess many desirable properties for microelectronic applications; for example, low dielectric constant and dissipation factor, low moisture absorption, rapid curing on hot plate without reaction by-products, minimum shrinkage in curing process, and no Cu migration issues. Recently, BCB-based products for thick film applications have been developed, which exhibited excellent dissipation factor and dielectric constant well into the GHz range, 0.002 and 2.50, respectively. Derived from these properties, the applications are developed in: bumping/wafer level packaging, Ga/As chip ILD, optical waveguide, flat panel display, and lately in BCB-coated Cu foil for build-up board. In this paper, we review the relevant properties of BCB, then the application areas in bumping/wafer level packaging and BCB-coated Cu foil for build-up board. (author). 11 refs., 4 tabs., 12 figs.
Khanina E. A.
2016-01-01
The article discusses the results of the pragmalinguistic experiment. Since language game is a result of speech creative work, which manifests the individuality of a linguistic personality, the politician can intentionally use language game and thereby consciously form his attractive image. The politician, who uses different kinds of language game, makes some personal characteristics building up the portrait aspect of effective political image more distinguished and thus affects the election ...
Build-up dynamics of heavy metals deposited on impermeable urban surfaces.
Wicke, D; Cochrane, T A; O'Sullivan, A
2012-12-30
A method using thin boards (3 cm thick, 0.56 m(2)) comprising different paving materials typically used in urban environments (2 asphalt types and concrete) was employed to specifically investigate air-borne deposition dynamics of TSS, zinc, copper and lead. Boards were exposed at an urban car park near vehicular traffic to determine the rate of contaminant build-up over a 13-day dry period. Concentration profiles from simulated rainfall wash-off were used to determine contaminant yields at different antecedent dry days. Maximum contaminant yields after 13 days of exposure were 2.7 kg ha(-1) for TSS, 35 g ha(-1) zinc, 2.3 g ha(-1) copper and 0.4 g ha(-1) lead. Accumulation of all contaminants increased over the first week and levelled off thereafter, supporting theoretical assumptions that contaminant accumulation on impervious surfaces asymptotically approaches a maximum. Comparison of different surface types showed approximately four times higher zinc concentrations in runoff from asphalt surfaces and two times higher TSS concentrations in runoff from concrete, which is attributed to different physical and chemical compositions of the pavement types. Contaminant build-up and wash-off behaviours were modelled using exponential and saturation functions commonly applied in the US EPA's Stormwater Management Model (SWMM) showing good correlation between measured and modelled concentrations. Maximum build-up, half-saturation time, build-up rate constants and wash-off coefficients, necessary for stormwater contaminant modelling, were determined for the four contaminants studied. These parameters are required to model contaminant concentrations in urban runoff assisting in stormwater management decisions. Copyright © 2012 Elsevier Ltd. All rights reserved.
Build-up material requirements in clinical dosimetry during total body irradiation treatments.
Butson, Martin; Pope, Dane; Haque, Mamoon; Chen, Tom; Song, Guangli; Whitaker, May
2016-01-01
Total body irradiation (TBI) treatments are mainly used in a preparative regimen for hematopoietic stem cell (or bone marrow) transplantation. Our standard clinical regimen is a 12 Gy/6 fraction bi-daily technique using 6MV X-rays at a large extended source to surface distance (SSD). This work investigates and quantifies the dose build-up characteristics and thus the requirements for bolus used for in vivo dosimetry for TBI applications. Percentage dose build-up characteristics of photon beams have been investigated at large extended SSDs using ionization chambers and Gafchromic film. Open field measurements at different field sizes and with differing scatter conditions such as the introduction of standard Perspex scattering plates at different distances to the measurement point were made in an effort to determine the required bolus/build-up material required for accurate determination of applied dose. Percentage surface dose values measured for open fields at 300 cm SSD were found to range from 20% up to 65.5% for fields 5 cm × 5 cm to 40 cm × 40 cm, respectively. With the introduction of 1 cm Perspex scattering plates used in TBI treatments, the surface dose values increased up to 83-90% (93-97% at 1 mm depth), depending on the position of the Perspex scattering plate compared to the measurement point. Our work showed that at least 5 mm water equivalent bolus/scatter material should be placed over the EBT3 film for accurate dose assessment for TBI treatments. Results also show that a small but measurable decrease in measured dose occurred with 5 mm water equivalent thick bolus material of areas '3 cm(2). As such, we recommend that 3 cm × 3 cm × 5 mm bolus build-up is the smallest size that should be placed over EBT3 Gafchromic film when used for accurate in vivo dosimetry for TBI applications.
The Model Proposal Which Aims to build up a Balanced Scorecard in Thermal Tourism Businesses
GENÇAY, İ. Cemal
2014-01-01
According to the Balanced Scorecard named as “corporate performance scorecard”, corporate performance, finance, customer, internal processes, learning and development must be evaluated with dimensions. Balanced Scorecard proposes that businesses are supposed to be managed with a strategic management system mainly based on measurement and evaluation. This study aims to present the model objectives, criteria and the process that guides about how to build up the corporate performance (Bala...
Ráhel, Jozef; Szalay, Zsolt; Čech, Jan; Morávek, Tomás
2016-04-01
Microfilaments of dielectric barrier discharge are known for their multiple re-appearance at the same spot on dielectrics. This effect of localized re-appearance is driven by residual excited species and ions, surface charge deposited on the dielectric and the local temperature build-up resulting in the local increase of reduced electric field E/ΔN. To assess the magnitude of the latter, the breakdown voltage vs. temperature up to 180 °C was carefully measured at coplanar DBD and used as an input into the numerical simulation of heat build-up by the train of discharge pulses. An average reduction of breakdown voltage was found to be 20 V/K. The model predicted a quasi-stable microfilament temperature into which the thermal build-up rapidly converges. Its magnitude agreed well with the reported rotational temperature of similar electrode configuration. The impact of quasi-stable temperature on microfilament formation dynamics is further discussed. Contribution to the Topical Issue "Recent Breakthroughs in Microplasma Science and Technology", edited by Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu.
Optimal Thermo-Structural Analysis for High Density Package Mounting on Build-up Board
Nakanishi, Tohru; Hase, Tomohiro
The importance of the high density packaging technology and mounting technology on the printed wiring build-up board has been increased for the consumer electric products. On the other hand, the chance to use the build-up boards for mounting the high density packages has been increased. However, the understanding that the reliability of the solder connection depends on the structure of the package, the motherboard, and the material properties, is not very high. In this paper, the reliability for high density packaging, mounted on the build-up board, is assessed. The compact numerical analysis model for the reliability assessment is suggested and the most reliable packaging design with optimizing each of the parameters is reported. For introduction to the reliability assessment of the FCA attachment, ceramic and silicon are compared as the inter-poser with the parameter of the solder height. The verification of the numerical analysis results using tests on the actual hardware is also shown. And the established numerical analysis model is applied to the study of influence of the copper balance between the front side and the back side copper layers.
Energy Technology Data Exchange (ETDEWEB)
Shen, Z; Greskovich, J; Xia, P [The Cleveland Clinic, Cleveland, OH (United States); Bzdusek, K [Philips, Fitchburg, WI (United States)
2015-06-15
Purpose: To generate virtual phantoms with clinically relevant deformation and use them to objectively evaluate geometric and dosimetric uncertainties of deformable image registration (DIR) algorithms. Methods: Ten lung cancer patients undergoing adaptive 3DCRT planning were selected. For each patient, a pair of planning CT (pCT) and replanning CT (rCT) were used as the basis for virtual phantom generation. Manually adjusted meshes were created for selected ROIs (e.g. PTV, lungs, spinal cord, esophagus, and heart) on pCT and rCT. The mesh vertices were input into a thin-plate spline algorithm to generate a reference displacement vector field (DVF). The reference DVF was used to deform pCT to generate a simulated replanning CT (srCT) that was closely matched to rCT. Three DIR algorithms (Demons, B-Spline, and intensity-based) were applied to these ten virtual phantoms. The images, ROIs, and doses were mapped from pCT to srCT using the DVFs computed by these three DIRs and compared to those mapped using the reference DVF. Results: The average Dice coefficients for selected ROIs were from 0.85 to 0.96 for Demons, from 0.86 to 0.97 for intensity-based, and from 0.76 to 0.95 for B-Spline. The average Hausdorff distances for selected ROIs were from 2.2 to 5.4 mm for Demons, from 2.3 to 6.8 mm for intensity-based, and from 2.4 to 11.4 mm for B-Spline. The average absolute dose errors for selected ROIs were from 0.2 to 0.6 Gy for Demons, from 0.1 to 0.5 Gy for intensity-based, and from 0.5 to 1.5 Gy for B-Spline. Conclusion: Virtual phantoms were modeled after patients with lung cancer and were clinically relevant for adaptive radiotherapy treatment replanning. Virtual phantoms with known DVFs serve as references and can provide a fair comparison when evaluating different DIRs. Demons and intensity-based DIRs were shown to have smaller geometric and dosimetric uncertainties than B-Spline. Z Shen: None; K Bzdusek: an employee of Philips Healthcare; J Greskovich: None; P Xia
Wallace, A C; Borkakoti, N; Thornton, J M
1997-11-01
It is well established that sequence templates such as those in the PROSITE and PRINTS databases are powerful tools for predicting the biological function and tertiary structure for newly derived protein sequences. The number of X-ray and NMR protein structures is increasing rapidly and it is apparent that a 3D equivalent of the sequence templates is needed. Here, we describe an algorithm called TESS that automatically derives 3D templates from structures deposited in the Brookhaven Protein Data Bank. While a new sequence can be searched for sequence patterns, a new structure can be scanned against these 3D templates to identify functional sites. As examples, 3D templates are derived for enzymes with an O-His-O "catalytic triad" and for the ribonucleases and lysozymes. When these 3D templates are applied to a large data set of nonidentical proteins, several interesting hits are located. This suggests that the development of a 3D template database may help to identify the function of new protein structures, if unknown, as well as to design proteins with specific functions.
Kachalo, Sëma
2015-05-14
Geometric and mechanical properties of individual cells and interactions among neighboring cells are the basis of formation of tissue patterns. Understanding the complex interplay of cells is essential for gaining insight into embryogenesis, tissue development, and other emerging behavior. Here we describe a cell model and an efficient geometric algorithm for studying the dynamic process of tissue formation in 2D (e.g. epithelial tissues). Our approach improves upon previous methods by incorporating properties of individual cells as well as detailed description of the dynamic growth process, with all topological changes accounted for. Cell size, shape, and division plane orientation are modeled realistically. In addition, cell birth, cell growth, cell shrinkage, cell death, cell division, cell collision, and cell rearrangements are now fully accounted for. Different models of cell-cell interactions, such as lateral inhibition during the process of growth, can be studied in detail. Cellular pattern formation for monolayered tissues from arbitrary initial conditions, including that of a single cell, can also be studied in detail. Computational efficiency is achieved through the employment of a special data structure that ensures access to neighboring cells in constant time, without additional space requirement. We have successfully generated tissues consisting of more than 20,000 cells starting from 2 cells within 1 hour. We show that our model can be used to study embryogenesis, tissue fusion, and cell apoptosis. We give detailed study of the classical developmental process of bristle formation on the epidermis of D. melanogaster and the fundamental problem of homeostatic size control in epithelial tissues. Simulation results reveal significant roles of solubility of secreted factors in both the bristle formation and the homeostatic control of tissue size. Our method can be used to study broad problems in monolayered tissue formation. Our software is publicly
SU-E-T-275: Dose Build Up and Bolusing Characteristics for Total Body Irradiation Dosimetry
Energy Technology Data Exchange (ETDEWEB)
Butson, M; Pope, D; Whitaker, M [Chris O’Brien LifeHouse, Sydney, NSW (Australia)
2015-06-15
Purpose: Total Body Irradiation (TBI) treatments are mainly used in a preparative regimen for haematopoietic stem cell (or bone marrow) transplantation. Our standard regimen is a 12 Gy / 6 fraction bi-daily technique. To evaluate the delivered dose homogeneity to the patient, EBT3 Gafchromic film is positioned at the head, neck, chest, pelvis and groin for all fractions. This work investigates and quantifies the build-up dose characteristics at TBI distances and requirements for in-vivo dosimetry bolusing. Methods: Percentage dose build up characteristics of photon beams have been investigated at large extended SSD’s using parallel plate ionisations chambers (Attix) and EBT3 Gafchromic film. Measurements were made to open fields at different field sizes as well as large 40cm × 40cm fields with differing scatter conditions such as the introduction of standard Perspex scattering plates at different distances to the measurement point. Results: Percentage surface dose measured values for open fields at 300 cm SSD were found to range from 20 % up to 65.5 % for fields of 5 cm × 5 cm to 40 cm × 40 cm. With the introduction of 1cm Perspex scattering plates used in TBI treatments the surface dose values increased up to 83% to 90%, depending on the position of the Perspex scattering plate compared to the measurement point. Our work showed that at least 3mm water equivalent bolus / scatter material should be placed over the EBT3 for accurate dose assessment for TBI treatments. Conclusion: Build up dose characteristics exist at long (300cm) SSD’s including treatments using Perspex scattering plates placed at various distances form the patient during TBI treatment. Top accurately assess the applied dose during treatment, in-vivo dosimeters such as Gafchromic EBT3 should have at least 3mm bolus / scatter material placed over them to measure actual applied doses.
Optimal Pile Arrangement for Minimizing Excess Pore Water Pressure Build-Up
DEFF Research Database (Denmark)
Barari, Amin; Saadati, Meysam; Ibsen, Lars Bo
2013-01-01
Numerical analysis of pile group in a liquefiable soil was considered to investigate the influence of pile spacing on excess pore pressure distribution and liquefaction potential. The analysis is conducted using a two-dimensional plain strain finite difference program considering a nonlinear...... constitutive model for sandy soil, strength and stiffness reduction, and pile-soil interaction. The Mohr-Coulomb constitutive model coupled with Byrne pore pressure build-up model have been employed in the analysis. Numerical analysis results show that pile groups have significant influence on the dynamic...... response of sandy soil as they reduce the amount of excess pore pressure development during seismic shaking and may even prevent liquefaction....
Optimal Pile Arrangement for Minimizing Excess Pore Water Pressure Build-Up
DEFF Research Database (Denmark)
Barari, Amin; Saadati, Meysam; Ibsen, Lars Bo
2013-01-01
Numerical analysis of pile group in a liquefiable soil was considered to investigate the influence of pile spacing on excess pore pressure distribution and liquefaction potential. The analysis is conducted using a two-dimensional plain strain finite difference program considering a nonlinear...... constitutive model for sandy soil, strength and stiffness reduction, and pile-soil interaction. The Mohr-Coulomb constitutive model coupled with Byrne pore pressure build-up model have been employed in the analysis. Numerical analysis results show that pile groups have significant influence on the dynamic...... response of sandy soil as they reduce the amount of excess pore pressure development during seismic shaking and may even prevent liquefaction....
Directory of Open Access Journals (Sweden)
Vishwanath P. Singh
2013-01-01
Full Text Available Geometric progression (GP method was utilized to investigate gamma-ray exposure build-up factors of fly-ash bricks for energies from 0.015 to 15 MeV up to 40 mfp penetration depth. The EBFs of the fly-ash bricks are dependent upon the photon energy, penetration depths, and the chemical compositions of the elements. Appreciable variations in exposure build-up factor (EBF are noted for the fly-ash bricks. The EBFs were found to be small in low and high photon energy regions whereas very large in medium energy region. EBF of the bricks is inversely proportional to equivalent atomic number below 10 mfp for entire energy region of interest 0.015 to 15 MeV. The EBFs of fly-ash, brick of mud, and common brick were similar at 1.5 MeV photon energy. The EBF of the fly-ash bricks was found to be higher than that of the brick of mud, and common brick. The fast neutron removal cross sections of the fly-ash bricks, brick of mud, and common bricks were also calculated which were found to be in the same order. It is expected that this study should be very directly useful for shielding effectiveness of fly-ash brick materials and dose estimation.
The Build-Up Course of Visuo-Motor and Audio-Motor Temporal Recalibration
Directory of Open Access Journals (Sweden)
Yoshimori Sugano
2011-10-01
Full Text Available The sensorimotor timing is recalibrated after a brief exposure to a delayed feedback of voluntary actions (temporal recalibration effect: TRE (Heron et al., 2009; Stetson et al., 2006; Sugano et al., 2010. We introduce a new paradigm, namely ‘synchronous tapping’ (ST which allows us to investigate how the TRE builds up during adaptation. In each experimental trial, participants were repeatedly exposed to a constant lag (∼150 ms between their voluntary action (pressing a mouse and a feedback stimulus (a visual flash / an auditory click 10 times. Immediately after that, they performed a ST task with the same stimulus as a pace signal (7 flashes / clicks. A subjective ‘no-delay condition’ (∼50 ms served as control. The TRE manifested itself as a change in the tap-stimulus asynchrony that compensated the exposed lag (eg, after lag adaptation, the tap preceded the stimulus more than in control and built up quickly (∼3–6 trials, ∼23–45 sec in both the visuo- and audio-motor domain. The audio-motor TRE was bigger and built-up faster than the visuo-motor one. To conclude, the TRE is comparable between visuo- and audio-motor domain, though they are slightly different in size and build-up rate.
MODEL TESTS OF HYDRAULIC FLOW CONDITIONS IN THE VEGETATION BUILD-UP FISHWAY
Directory of Open Access Journals (Sweden)
Tomasz Tymiński
2015-10-01
Full Text Available Our engineering activity aiming at keeping ecological corridors in rivers are a difficult and complex issue that requires specialist knowledge in many disciplines. One of the installations for ensuring ecological continuum river are fishways, particularly their “near-natural” designs. They resemble mountain streams and creeks. Natural materials, such as wood, vegetation, gravel, stones and rocks are used for their construction. Design of hydraulic fishways based solely on the criteria of maximum speed vmax and parameter of unitary energy of water E, it does not give complete information about the effectiveness of these devices. In order to produce the optimal flow conditions for ichthyofauna, very useful are spatial structure research of hydraulic parameters, such as disorders of flow velocity field or distributions of the turbulence number Tu. The article presents an example of such a study, which the authors carried out on the model seminatural fishway in the water laboratory in Institute of Environmental Engineering in Wrocław. The results were used to assess the accuracy of the functioning of the fishway. The tested combination of “vegetated baffles” and “pools” in the fishway model was found to be optimal for the ichthyofauna. Vegetation build-up in fishways is an interesting and proecological alternative for “heavy” technical build-up.
Investigation of Pectin/Chitosan Multilayers Build-up on Corona Charged Polylactide Substrates
Yovcheva, T. A.; Marudova, M. G.; Viraneva, A. P.; Gencheva, E. A.; Mekishev, G. A.; Sainov, S. H.
2010-01-01
The aim of the present research is to investigate the formation and stability of pectin/chitosan multilayer films on preliminary corona charged polylactide substrate with different polarity. For this purpose two different multilayer structures with alternative ordering of polycation and polyanion layers were prepared. Layer-by-layer (LbL) deposition technique was used for multilayer build-up. The FT-IR transmittance spectra of the substrates with multilayers indicated of the presence of pectin and chitosan. The intensity of the typical bands was found to increase with increasing of the number of the deposited layers. The stability and physico-chemical properties of the multilayer structures were investigated by determination of surface refractive index and swelling behaviour. Multilayers are stable enough in distilled water and their equilibrium degree of swelling increases with the increase of build-up layers. This relation is correlated with the increased amount of hydrophilic biopolymers. It was found out that chitosan/pectin multilayers buil-up on negatively charged substrate consist of higher amount of polyelectrolytes and are more stable in distilled water.
Optical fiber sensors and their application in monitoring stress build-up in dental resin cements
Ottevaere, H.; Tabak, M.; Fernandez Fernandez, A.; Berghmans, F.; Thienpont, H.
2005-09-01
The field of optical fiber sensing is highly diverse and this diversity is perceived as a great advantage over more conventional sensors in that an optical sensor can be tailored to measure any of a myriad of physical parameters. In this paper we present a niche application for optical fiber sensors in the domain of biophotonics, namely the monitoring of stress build-up during the curing process of dental resin cements. We discuss the origin of this stress build-up and the problems it can cause when treating patients. Optical fiber sensors aim at excelling in two kind of applications: firstly to perform quality control on batch produced dental cements and measure their total material shrinkage, secondly to monitor the hardening of the cement during in-vivo measurements resulting in the dynamic measurement of the shrinkage and to control the stress in a facing based restoration. We therefore investigated two types of optical fiber sensors as alternatives to conventional measurement techniques; namely polarimetric optical fiber sensors and fiber Bragg gratings written in polarization maintaining fibers. After discussing the results obtained with both optical fiber sensors, we will conclude with a critical assessment of the suitability of the two proposed sensing configurations for multi-parameter stress monitoring.
Effects of damage build-up in range profiles in crystalline Si; Molecular dynamics simulations
Peltola, J; Keinonen, J
2002-01-01
Molecular dynamics (MD) has been successful in predicting range profiles for ions implanted into crystalline materials in the fluence regime where it can be approximated that changes in the sample structure do not affect the profiles. Many experimental distributions are, however, strongly fluence-dependent due to the amorphization of the crystalline material. This has so far been taken into account only in some binary-collision-approximation calculations with a damage build-up model that depends on the probability of amorphization occurring at a certain depth. We present here a fast MD model for predicting range profiles of ions in crystalline Si. The model includes cumulative damage build-up, where the amorphization states of the material are taken from MD simulations of cascade damage. The method can be used to predict profiles for any material. We used silicon because of the large amount of experimental data available. No free parameters were used. Comparison of results with the results of a wide range of ...
Geometrical Bioelectrodynamics
Ivancevic, Vladimir G
2008-01-01
This paper proposes rigorous geometrical treatment of bioelectrodynamics, underpinning two fast-growing biomedical research fields: bioelectromagnetism, which deals with the ability of life to produce its own electromagnetism, and bioelectromagnetics, which deals with the effect on life from external electromagnetism. Keywords: Bioelectrodynamics, exterior geometrical machinery, Dirac-Feynman quantum electrodynamics, functional electrical stimulation
Impact of eccentricity build-up and graveyard disposal Strategies on MEO navigation constellations
Radtke, Jonas; Domínguez-González, Raúl; Flegel, Sven K.; Sánchez-Ortiz, Noelia; Merz, Klaus
2015-12-01
With currently two constellations being in or close to the build-up phase, in a few years the Medium Earth Orbit (MEO) region will be populated with four complete navigation systems in relatively close orbital altitudes: The American GPS, Russian GLONASS, European Galileo, and Chinese BeiDou. To guarantee an appropriate visibility of constellation satellites from Earth, these constellations rely on certain defined orbits. For this, both the repeat pattern, which is basically defined by the semimajor axis and inclination, as well as the orbital planes, which are defined by the right ascension of ascending node, are determining values. To avoid an overcrowding of the region of interest, the disposal of satellites after their end-of-life is recommended. However, for the MEO region, no internationally agreed mitigation guidelines exist. Because of their distances to Earth, ordinary disposal manoeuvres leading to a direct or delayed re-entry due to atmospheric drag are not feasible: The needed fuel masses for such manoeuvres are by far above the reasonable limits and available fuel budgets. Thus, additional approaches have to be applied. For this, in general two options exist: disposal to graveyard orbits or the disposal to eccentricity build-up orbits. In the study performed, the key criterion for the graveyard strategy is that the disposed spacecraft must keep a safe minimum distance to the altitude of the active constellation on a long-term time scale of up to 200 years. This constraint imposes stringent requirements on the stability of the graveyard orbit. Similar disposals are also performed for high LEO satellites and disposed GEO payloads. The eccentricity build-up strategy on the other hand uses resonant effects between the Earth's geopotential, the Sun and the Moon. Depending on the initial conditions, these can cause a large eccentricity build-up, which finally can lead to a re-entry of the satellite. In this paper, the effects of applying either the first or
An ECG waveform recognition algorithm based on geometric characteristics%一种基于几何特征的 ECG 波形识别算法
Institute of Scientific and Technical Information of China (English)
李锋; 陈美丽
2015-01-01
目的：ECG自动分析系统由两部分组成：波形识别和智能诊断。在实际应用中，心电波形识别是该系统的关键。波形识别的精确性和可靠性决定了心脏病诊断的可靠性。为提高波形识别的速率及准确度，本文提出一种基于几何特征的ECG波形识别算法。方法首先利用数字滤波算法对信号进行预处理，提高信号的信噪比，然后通过改进的二阶导数计算出数据的几何特征：点的斜率和运动趋势，并在此基础上，结合ECG波形的实际物理特征，利用算法实现T波、P波、QRS波群的起点、终点以及波峰波谷的自动识别。结果统计分析结果表明，本算法能够快速高效地识别ECG波形。同时将该算法与其他当前各种ECG波形识别算法进行对比，该识别算法在识别的精确性与阳性预测值方面具有更好的性能。结论本文提出的基于几何特征的ECG波形识别算法可以进一步提高当前ECG波形识别算法的性能。%Objective ECG analysis diagnosis system mainly consists of two phases: waveform recognition and intelligent diagnosis .Accuracy and reliability of ECG waveform recognition determine the diagnosis and treatment of heart disease .A waveform recognition algorithm based on geometric characteristics is proposed in this paper to improve the detection rate and accuracy of waveform recognition .Methods Firstly, signals are preprocessed to improve noise ratio by digital filtering algorithm .Secondly , we calculate certain geometric characteristics such as the slope and the movement tendency of points with improved second derivative.Finally, we can automatically recognize the onset , the offset, the peak and the trough of T wave , P wave, QRS complex with the actual physical characteristics of ECG waveform on the basis of the previous results.Results Statistical analysis shows that our method can recognize the ECG wave fast and effectively .We also compare this
Directory of Open Access Journals (Sweden)
Brochet Bruno
2011-10-01
Full Text Available Abstract Background Vasogenic edema dynamically accumulates in many brain disorders associated with brain inflammation, with the critical step of edema exacerbation feared in patient care. Water entrance through blood-brain barrier (BBB opening is thought to have a role in edema formation. Nevertheless, the mechanisms of edema resolution remain poorly understood. Because the water channel aquaporin 4 (AQP4 provides an important route for vasogenic edema resolution, we studied the time course of AQP4 expression to better understand its potential effect in countering the exacerbation of vasogenic edema. Methods Focal inflammation was induced in the rat brain by a lysolecithin injection and was evaluated at 1, 3, 7, 14 and 20 days using a combination of in vivo MRI with apparent diffusion coefficient (ADC measurements used as a marker of water content, and molecular and histological approaches for the quantification of AQP4 expression. Markers of active inflammation (macrophages, BBB permeability, and interleukin-1β and markers of scarring (gliosis were also quantified. Results This animal model of brain inflammation demonstrated two phases of edema development: an initial edema build-up phase during active inflammation that peaked after 3 days (ADC increase was followed by an edema resolution phase that lasted from 7 to 20 days post injection (ADC decrease and was accompanied by glial scar formation. A moderate upregulation in AQP4 was observed during the build-up phase, but a much stronger transcriptional and translational level of AQP4 expression was observed during the secondary edema resolution phase. Conclusions We conclude that a time lag in AQP4 expression occurs such that the more significant upregulation was achieved only after a delay period. This change in AQP4 expression appears to act as an important determinant in the exacerbation of edema, considering that AQP4 expression is insufficient to counter the water influx during the build-up
Importance of salinity stratification in the build up of El Nino
Maes, C.; Picaut, J.; Belamari, S.
2003-04-01
An increase of mass and heat content in the equatorial band of the Pacific Ocean, and in particular in the western part of the basin, appears necessary for the initiation of El Nino. This build up has led to the recharge theory of El Nino. The western Pacific warm pool is also characterized by the presence of specific salinity stratification known as the barrier layer. This barrier isolates the warm surface water from entrainment cooling and potentially preserves the heat content prior to El Nino. The importance of salinity stratification in the build up of El Nino is investigated using a general circulation coupled model of the tropical Pacific. The Meteo-France/ARPEGE global atmospheric model coupled to the LODYC/OPA ocean model is able to reproduce self-sustained El Nino events. In particular, this coupled model displays an increase of heat content in the western equatorial Pacific the year prior to each El Nino event. The methodology consists of removing the stratification effect of salinity in the vertical mixing parameterization the year prior to El Nino, and then plugs it back. The cutoff is restricted to the western side of the equatorial band where sea surface temperature (SST) is greater than 28C. By removing the barrier layer the year prior to El Nino, the main effect is to reduce the ocean heat content in the western part of the equatorial band and increase it in the east. When the stratification effect of salinity is plug back, El Nino is greatly reduced or even aborted. This has tested over three El Nino events of different intensities and through 5 additional member ensemble. The failure for El Nino to start is statistically significant and proves that salinity stratification plays a crucial role in the build up of El Nino. Detailed analyses indicate that vertical diffusion in the warm pool and SST-wind coupling in the central Pacific are essential to set up the favorable condition for the initiation of El Nino.
Geometric Algorithms for Trajectory Analysis
Staals, Frank
2015-01-01
Technology such as the Global Positing System (GPS) has made tracking moving entities easy and cheap. As a result there is a large amount of trajectory data available, and an increasing demand on tools and techniques to analyze such data. We consider several analysis tasks for trajectory data, and d
Build-up and decline of organic matter during PeECE III
Directory of Open Access Journals (Sweden)
K. G. Schulz
2007-11-01
Full Text Available Increasing atmospheric carbon dioxide (CO_{2} concentrations due to anthropogenic fossil fuel combustion currently change the ocean's chemistry. Increasing oceanic [CO_{2}] and subsequent decreasing seawater pH have the potential to significantly impact marine life. Here we describe and analyze the build-up and decline of a natural phytoplankton bloom initiated during the 2005 mesocosm Pelagic Ecosystem CO_{2} Enrichment study (PeECE III. We show that processes of inorganic carbon uptake in mixed surface waters and organic carbon export to depth were significantly enhanced at elevated CO_{2}, while ammonium regeneration in deep waters was substantially reduced. This has important implications for our understanding of pelagic ecosystem functioning and future carbon cycling.
Building-up a Smile in a 5-Year-Old Child: A Case Report.
Marwaha, Mohita; Bhat, Manohar; Singh Nanda, Kanwar Deep
2012-05-01
A variety of therapeutic modalities, from removable partial dentures to conventional fixed space maintainer can be used for the replacement of traumatically missing or carious lost primary anterior teeth. Dentistry has advanced to a point where it is undesirable for children to be partially edentulous or to have unattractive anterior teeth. The introduction of new materials and adhesive systems in dentistry, offers a new reconstructive alternative for severely destroyed or lost primary anterior teeth. The purpose of this article was to present a clinical case of four primary anterior teeth replacement by means of fiber-reinforced composite bridge. This technique offers a conservative, esthetic and noninvasive treatment. It can be considered, as a long- lasting reversible provisional treatment. How to cite this article: Marwaha M, Bhat M, Nanda KDS. Building-up a Smile in a 5-Year-Old Child: A Case Report. Int J Clin Pediatr Dent 2012;5(2):151-154.
Model Study of the Pressure Build-Up during Subcutaneous Injection
DEFF Research Database (Denmark)
Thomsen, Maria; Hernandez Garcia, Anier; Mathiesen, Joachim;
2014-01-01
of a porous medium. For equivalent injection forces we measure the change in the infusion rate between injections in air at atmospheric pressure and in tissue. From a best fit with our model, we then determine the flow permeability as well as the bulk modulus of the tissue, estimated to be of the order 10......In this study we estimate the subcutaneous tissue counter pressure during drug infusion from a series of injections of insulin in type 2 diabetic patients using a non-invasive method. We construct a model for the pressure evolution in subcutaneous tissue based on mass continuity and the flow laws......-11-10-10 m2 and 105 Pa, respectively. The permeability is in good agreement with reported values for adipose porcine tissue. We suggest our model as a general way to estimate the pressure build-up in tissue during subcutaneous injection....
Directory of Open Access Journals (Sweden)
Khanina E. A.
2016-02-01
Full Text Available The article discusses the results of the pragmalinguistic experiment. Since language game is a result of speech creative work, which manifests the individuality of a linguistic personality, the politician can intentionally use language game and thereby consciously form his attractive image. The politician, who uses different kinds of language game, makes some personal characteristics building up the portrait aspect of effective political image more distinguished and thus affects the election decision of the voter. It has been studied whether language game influences such characteristics as determination, insistence, persuasiveness, emotionality, confidence, energy, sense of responsibility, dedication, trustworthiness, honesty, a certain hardness, decisiveness, autonomy, adherence to principles and assertiveness. It has been concluded that language game influences 11 of the 15 characteristics, this fact confirms the hypothesis
Model study of the pressure build-up during subcutaneous injection.
Thomsen, Maria; Hernandez-Garcia, Anier; Mathiesen, Joachim; Poulsen, Mette; Sørensen, Dan N; Tarnow, Lise; Feidenhans'l, Robert
2014-01-01
In this study we estimate the subcutaneous tissue counter pressure during drug infusion from a series of injections of insulin in type 2 diabetic patients using a non-invasive method. We construct a model for the pressure evolution in subcutaneous tissue based on mass continuity and the flow laws of a porous medium. For equivalent injection forces we measure the change in the infusion rate between injections in air at atmospheric pressure and in tissue. From a best fit with our model, we then determine the flow permeability as well as the bulk modulus of the tissue, estimated to be of the order 10-11-10-10 m2 and 105 Pa, respectively. The permeability is in good agreement with reported values for adipose porcine tissue. We suggest our model as a general way to estimate the pressure build-up in tissue during subcutaneous injection.
Model study of the pressure build-up during subcutaneous injection
DEFF Research Database (Denmark)
Thomsen, Maria; Hernandez-Garcia, Anier; Mathiesen, Joachim
2014-01-01
In this study we estimate the subcutaneous tissue counter pressure during drug infusion from a series of injections of insulin in type 2 diabetic patients using a non-invasive method. We construct a model for the pressure evolution in subcutaneous tissue based on mass continuity and the flow laws...... of a porous medium. For equivalent injection forces we measure the change in the infusion rate between injections in air at atmospheric pressure and in tissue. From a best fit with our model, we then determine the flow permeability as well as the bulk modulus of the tissue, estimated to be of the order 10......-11-10-10 m2 and 105 Pa, respectively. The permeability is in good agreement with reported values for adipose porcine tissue. We suggest our model as a general way to estimate the pressure build-up in tissue during subcutaneous injection....
The Accelerated Build-up of the Red Sequence in High Redshift Galaxy Clusters
Cerulo, P; Lidman, C; Demarco, R; Huertas-Company, M; Mei, S; Sánchez-Janssen, R; Barrientos, L F; Muñoz, R P
2016-01-01
We analyse the evolution of the red sequence in a sample of galaxy clusters at redshifts $0.8 11.5$) red sequence galaxies in the WINGS clusters, which do not include only the brightest cluster galaxies and which are not present in the HCS clusters, suggesting that they formed at epochs later than $z=0.8$. The comparison with the luminosity distribution of a sample of passive red sequence galaxies drawn from the COSMOS/UltraVISTA field in the photometric redshift range $0.8
Building-up a Smile in a 5-Year-Old Child: A Case Report
Bhat, Manohar; Singh Nanda, Kanwar Deep
2012-01-01
ABSTRACT A variety of therapeutic modalities, from removable partial dentures to conventional fixed space maintainer can be used for the replacement of traumatically missing or carious lost primary anterior teeth. Dentistry has advanced to a point where it is undesirable for children to be partially edentulous or to have unattractive anterior teeth. The introduction of new materials and adhesive systems in dentistry, offers a new reconstructive alternative for severely destroyed or lost primary anterior teeth. The purpose of this article was to present a clinical case of four primary anterior teeth replacement by means of fiber-reinforced composite bridge. This technique offers a conservative, esthetic and noninvasive treatment. It can be considered, as a long- lasting reversible provisional treatment. How to cite this article: Marwaha M, Bhat M, Nanda KDS. Building-up a Smile in a 5-Year-Old Child: A Case Report. Int J Clin Pediatr Dent 2012;5(2):151-154. PMID:25206158
Neural correlate of subjective sensory experience gradually builds up across cortical areas
de Lafuente, Victor; Romo, Ranulfo
2006-01-01
When a sensory stimulus is presented, many cortical areas are activated, but how does the representation of a sensory stimulus evolve in time and across cortical areas during a perceptual judgment? We investigated this question by analyzing the responses from single neurons, recorded in several cortical areas of parietal and frontal lobes, while trained monkeys reported the presence or absence of a mechanical vibration of varying amplitude applied to the skin of one fingertip. Here we show that the strength of the covariations between neuronal activity and perceptual judgments progressively increases across cortical areas as the activity is transmitted from the primary somatosensory cortex to the premotor areas of the frontal lobe. This finding suggests that the neuronal correlates of subjective sensory experience gradually build up across somatosensory areas of the parietal lobe and premotor cortices of the frontal lobe. PMID:16924098
Experimental investigation of the reaction-build-up for plastic bonded explosive JOB-9003
Directory of Open Access Journals (Sweden)
Xu Zhang
2017-05-01
Full Text Available In order to measure the shock initiation behavior of JOB-9003 explosives, Al-based embedded multiple electromagnetic particle velocity gauge technique has been developed. In addition, a gauge element called the shock tracker has been used to monitor the progress of the shock front as a function of time, thus providing a position–time trajectory of the wave front as it moves through the explosive sample. The data is used to determine the position and time for shock to detonation transition. All the experimental results show that the rising-up time of Al-based electromagnetic particle velocity gauge is very short (<20 ns; the reaction-build-up velocity profiles and the position–time for shock to detonation transition of HMX-based plastic bonded explosive (PBX JOB-9003 with 1–8 mm depth from the origin of the impact plane under different initiation pressures were obtained with high accuracy.
Energy Technology Data Exchange (ETDEWEB)
Suurs, Roald A.A. [Innovation Studies Group, Copernicus Institute for Sustainable Development and Innovation, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht (Netherlands); TNO Built Environment and Geosciences, Business Unit Innovation and Environment, Van Mourik Broekmanweg 6, 2628 XE Delft (Netherlands); Hekkert, Marko P.; Smits, Ruud E.H.M. [Innovation Studies Group, Copernicus Institute for Sustainable Development and Innovation, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht (Netherlands)
2009-12-15
This study provides insight into the development of hydrogen and fuel cell technologies in the Netherlands (1980-2007). This is done by applying a Technological Innovation System (TIS) approach. This approach takes the perspective that a technology is shaped by a surrounding network of actors, institutions and technologies. When a technology is in an early stage of development, a TIS has yet to be built up in order to propel technological progress. This build-up process is studied for the hydrogen and fuel cell innovation system in the Netherlands. This is done by systematically studying the dynamics of seven key activities that accelerated (or slowed down) developments around hydrogen and fuel cell technologies. The analysis contributes to a better understanding of these dynamics and of the drivers and barriers that caused them to emerge. The study derives important lessons for practitioners. (author)
Resonant laser power build-up in ALPS - a "light-shining-through-walls" experiment -
Ehret, Klaus; Ghazaryan, Samvel; Hildebrandt, Matthias; Knabbe, Ernst-Axel; Kracht, Dietmar; Lindner, Axel; List, Jenny; Meier, Tobias; Meyer, Niels; Notz, D; Redondo, Javier; Ringwald, Andreas; Wiedemann, Günter; Willke, Benno
2009-01-01
The ALPS collaboration runs a light-shining-through-walls (LSW) experiment to search for photon oscillations into "weakly interacting sub-eV particles" (WISPs) inside of a superconducting HERA dipole magnet at the site of DESY. In this paper we report on the first successful integration of a large-scale optical cavity to boost the available power for WISP production in this type of experiments. The key elements are a frequency tunable narrow line-width continuous wave laser acting as the primary light source and an electronic feed-back control loop to stabilize the power build-up. We describe and characterize our apparatus and demonstrate the data analysis procedures on the basis of a brief exemplary run.
Investigating the build-up of precedence effect using reflection masking
DEFF Research Database (Denmark)
Hartcher-O'Brien, Jessica; Buchholz, Jörg
2006-01-01
The auditory processing level involved in the build-up of precedence [Freyman et al., J. Acoust. Soc. Am. 90, 874–884 (1991)] has been investigated here by employing reflection masked threshold (RMT) techniques. Given that RMT techniques are generally assumed to address lower levels of the auditory...... signal processing, such an approach represents a bottom-up approach to the buildup of precedence. Three conditioner configurations measuring a possible buildup of reflection suppression were compared to the baseline RMT for four reflection delays ranging from 2.5–15 ms. No buildup of reflection...... suppression was observed for any of the conditioner configurations. Buildup of template (decrease in RMT for two of the conditioners), on the other hand, was found to be delay dependent. For five of six listeners, with reflection delay=2.5 and 15 ms, RMT decreased relative to the baseline. For 5- and 10-ms...
Structure build-up and evolution in the drying of sessile blood droplets
Craster, Richard; Uppal, Aran; Matar, Omar
2016-11-01
Experimental observations have recorded blood undergoing a sol-gel transition during the evaporation process. Consequently, the rheology becomes non-uniform throughout the droplet and exhibits transitional complex phenomena that we must capture if we wish to accurately model the evaporative/cracking process. We propose a model where thixotropy is introduced to capture the evolving rheology as evaporation occurs. Thixotropy is often used to describe fluids which exhibit a decrease in viscosity due to flow and subsequent slow recovery of viscosity after the cessation of the flow. We introduce an additional parameter to describe the internal structure of the fluid at each point and consider a droplet in the limit of the lubrication approximation. We present a discussion of our results that demonstrates the dependence of structure build-up, which accompanies the spatio-temporal evolution of the drop, on system parameters. EPSRC UK Centre for Doctoral Training.
Model study of the pressure build-up during subcutaneous injection.
Directory of Open Access Journals (Sweden)
Maria Thomsen
Full Text Available In this study we estimate the subcutaneous tissue counter pressure during drug infusion from a series of injections of insulin in type 2 diabetic patients using a non-invasive method. We construct a model for the pressure evolution in subcutaneous tissue based on mass continuity and the flow laws of a porous medium. For equivalent injection forces we measure the change in the infusion rate between injections in air at atmospheric pressure and in tissue. From a best fit with our model, we then determine the flow permeability as well as the bulk modulus of the tissue, estimated to be of the order 10-11-10-10 m2 and 105 Pa, respectively. The permeability is in good agreement with reported values for adipose porcine tissue. We suggest our model as a general way to estimate the pressure build-up in tissue during subcutaneous injection.
CORAL: building up the model for bioconcentration factor and defining it's applicability domain.
Toropov, A A; Toropova, A P; Lombardo, A; Roncaglioni, A; Benfenati, E; Gini, G
2011-04-01
CORAL (CORrelation And Logic) software can be used to build up the quantitative structure--property/activity relationships (QSPR/QSAR) with optimal descriptors calculated with the simplified molecular input line entry system (SMILES). We used CORAL to evaluate the applicability domain of the QSAR models, taking a model of bioconcentration factor (logBCF) as example. This model's based on a large training set of more than 1000 chemicals. To improve the model is predictivity and reliability on new compounds, we introduced a new function, which uses the Delta(obs) = logBCF(expr)--logBCF(calc) of the predictions on the chemicals in the training set. With this approach, outliers are eliminated from the phase of training. This proved useful and increased the model's predictivity. Copyright © 2011 Elsevier Masson SAS. All rights reserved.
Directory of Open Access Journals (Sweden)
Trunev A. P.
2014-05-01
Full Text Available In this article we have investigated the solutions of Maxwell's equations, Navier-Stokes equations and the Schrödinger associated with the solutions of Einstein's equations for empty space. It is shown that in some cases the geometric instability leading to turbulence on the mechanism of alternating viscosity, which offered by N.N. Yanenko. The mechanism of generation of matter from dark energy due to the geometric turbulence in the Big Bang has been discussed
An Empirical Model for Build-Up of Sodium and Calcium Ions in Small Scale Reverse Osmosis
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Subriyer Nasir
2011-05-01
Full Text Available A simple models for predicting build-up of solute on membrane surface were formulated in this paper. The experiments were conducted with secondary effluent, groundwater and simulated feed water in small-scale of RO with capacity of 2000 L/d. Feed water used in the experiments contained varying concentrations of sodium, calcium, combined sodium and calcium. In order to study the effect of sodium and calcium ions on membrane performance, experiments with ground water and secondary effluent wastewater were also performed. Build-up of salts on the membrane surface was calculated by measuring concentrations of sodium and calcium ions in feed water permeate and reject streams using Atomic Absorption Spectrophotometer (AAS. Multiple linear regression of natural logarithmic transformation was used to develop the model based on four main parameters that affect the build-up of solute in a small scale of RO namely applied pressure, permeate flux, membrane resistance, and feed concentration. Experimental data obtained in a small scale RO unit were used to develop the empirical model. The predicted values of theoretical build-up of sodium and calcium on membrane surface were found in agreement with experimental data. The deviation in the prediction of build-up of sodium and calcium were found to be 1.4 to 10.47 % and 1.12 to 4.46%, respectively.
Muniz Oliva, Waldyr
2002-01-01
Geometric Mechanics here means mechanics on a pseudo-riemannian manifold and the main goal is the study of some mechanical models and concepts, with emphasis on the intrinsic and geometric aspects arising in classical problems. The first seven chapters are written in the spirit of Newtonian Mechanics while the last two ones as well as two of the four appendices describe the foundations and some aspects of Special and General Relativity. All the material has a coordinate free presentation but, for the sake of motivation, many examples and exercises are included in order to exhibit the desirable flavor of physical applications.
Geometrically Consistent Mesh Modification
Bonito, A.
2010-01-01
A new paradigm of adaptivity is to execute refinement, coarsening, and smoothing of meshes on manifolds with incomplete information about their geometry and yet preserve position and curvature accuracy. We refer to this collectively as geometrically consistent (GC) mesh modification. We discuss the concept of discrete GC, show the failure of naive approaches, and propose and analyze a simple algorithm that is GC and accuracy preserving. © 2010 Society for Industrial and Applied Mathematics.
Build-up and decline of organic matter during PeECE III
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K. G. Schulz
2008-05-01
Full Text Available Increasing atmospheric carbon dioxide (CO_{2} concentrations due to anthropogenic fossil fuel combustion are currently changing the ocean's chemistry. Increasing oceanic [CO_{2}] and consequently decreasing seawater pH have the potential to significantly impact marine life. Here we describe and analyze the build-up and decline of a natural phytoplankton bloom initiated during the 2005 mesocosm Pelagic Ecosystem CO_{2} Enrichment study (PeECE III. The draw-down of inorganic nutrients in the upper surface layer of the mesocosms was reflected by a concomitant increase of organic matter until day t_{11}, the peak of the bloom. From then on, biomass standing stocks steadily decreased as more and more particulate organic matter was lost into the deeper layer of the mesocosms. We show that organic carbon export to the deeper layer was significantly enhanced at elevated CO_{2}. This phenomenon might have impacted organic matter remineralization leading to decreased oxygen concentrations in the deeper layer of the high CO_{2} mesocosms as indicated by deep water ammonium concentrations. This would have important implications for our understanding of pelagic ecosystem functioning and future carbon cycling.
Understanding innovation system build up. The rise and fall of the Dutch PV Innovation System
Energy Technology Data Exchange (ETDEWEB)
Negro, S.O.; Vasseur, V.; Hekkert, M.P. [Department of Innovation Studies, Copernicus Institute for Sustainable Development and Innovation, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht (Netherlands); Van Sark, W.G.J.H.M. [Department of Science, Technology and Society, Copernicus Institute for Sustainable Development and Innovation, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht (Netherlands)
2009-03-15
Renewable energy technologies have a hard time to break through in the existing energy regime. In this paper we focus on analysing the mechanisms behind this problematic technology diffusion. We take the theoretical perspective of innovation system dynamics and apply this to photovoltaic solar energy technology (PV) in the Netherlands. The reason for this is that there is a long history of policy efforts in The Netherlands to stimulate PV but results in terms of diffusion of PV panels is disappointingly low, which clearly constitutes a case of slow diffusion. The history of the development of the PV innovation system is analysed in terms of seven key processes that are essential for the build up of innovation systems. We show that the processes related to knowledge development are very stable but that large fluctuations are present in the processes related to 'guidance of the search' and 'market formation'. Surprisingly, entrepreneurial activities are not too much affected by fluctuating market formation activities. We relate this to market formation in neighbouring countries and discuss the theoretical implications for the technological innovation system framework.
Renewable build-up pathways for the US: Generation costs are not system costs
Becker, Sarah; Andresen, Gorm B; Jacobson, Mark Z; Schramm, Stefan; Greiner, Martin
2014-01-01
The transition to a future electricity system based primarily on wind and solar PV is examined for all regions in the contiguous US. We present optimized pathways for the build-up of wind and solar power for least backup energy needs as well as for least cost obtained with a simplified, lightweight model based on long-term high resolution weather-determined generation data. In the absence of storage, the pathway which achieves the best match of generation and load, thus resulting in the least backup energy requirements, generally favors a combination of both technologies, with a wind/solar PV energy mix of about 80/20 in a fully renewable scenario. The least cost development is seen to start with 100% of the technology with the lowest average generation costs first, but with increasing renewable installations, economically unfavorable excess generation pushes it toward the minimal backup pathway. Surplus generation and the entailed costs can be reduced significantly by combining wind and solar power, and/or a...
An Effective Strategy to Build Up a Balanced Test Suite for Spectrum-Based Fault Localization
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Ning Li
2016-01-01
Full Text Available During past decades, many automated software faults diagnosis techniques including Spectrum-Based Fault Localization (SBFL have been proposed to improve the efficiency of software debugging activity. In the field of SBFL, suspiciousness calculation is closely related to the number of failed and passed test cases. Studies have shown that the ratio of the number of failed and passed test case has more significant impact on the accuracy of SBFL than the total number of test cases, and a balanced test suite is more beneficial to improving the accuracy of SBFL. Based on theoretical analysis, we proposed an PNF (Passed test cases, Not execute Faulty statement strategy to reduce test suite and build up a more balanced one for SBFL, which can be used in regression testing. We evaluated the strategy making experiments using the Siemens program and Space program. Experiments indicated that our PNF strategy can be used to construct a new test suite effectively. Compared with the original test suite, the new one has smaller size (average 90% test case was reduced in experiments and more balanced ratio of failed test cases to passed test cases, while it has the same statement coverage and fault localization accuracy.
Vroomen, Jean; van Linden, Sabine; de Gelder, Béatrice; Bertelson, Paul
2007-02-01
Exposure to incongruent auditory and visual speech produces both visual recalibration and selective adaptation of auditory speech identification. In an earlier study, exposure to an ambiguous auditory utterance (intermediate between /aba/ and /ada/) dubbed onto the video of a face articulating either /aba/ or /ada/, recalibrated the perceived identity of auditory targets in the direction of the visual component, while exposure to congruent non-ambiguous /aba/ or /ada/ pairs created selective adaptation, i.e. a shift of perceived identity in the opposite direction [Bertelson, P., Vroomen, J., & de Gelder, B. (2003). Visual recalibration of auditory speech identification: a McGurk aftereffect. Psychological Science, 14, 592-597]. Here, we examined the build-up course of the after-effects produced by the same two types of bimodal adapters, over a 1-256 range of presentations. The (negative) after-effects of non-ambiguous congruent adapters increased monotonically across that range, while those of ambiguous incongruent adapters followed a curvilinear course, going up and then down with increasing exposure. This pattern is discussed in terms of an asynchronous interaction between recalibration and selective adaptation processes.
Integration of micro-filtration into osmotic membrane bioreactors to prevent salinity build-up.
Wang, Xinhua; Yuan, Bo; Chen, Yao; Li, Xiufen; Ren, Yueping
2014-09-01
The high salinity remains as one of major obstacles of the osmotic membrane bioreactor (OMBR). In this study, a new pathway was explored to prevent the salinity build-up by integrating the micro-filtration (MF) membrane to the OMBR (MF-OMBR). The results indicated that the salinity characterized by conductivity in the MF-OMBR was effectively alleviated and controlled at a lower value of about 5 mS/cm, and the stable flux of forward osmosis (FO) membrane correspondingly increased to approximately 5.5L/(m(2)h). Besides, the addition of MF membrane in the OMBR could increase the total organic carbon (TOC) and ammonium nitrogen (NH3-N) removals due to the activated sludge by improving the microbial activity. The membrane fouling especially the reversible fouling in the MF-OMBR was severer compared to that in the conventional OMBR, which resulted in a lower water flux than the expectation due to the increase of filtration resistance and external concentration polarization.
Comparative study of mechanical properties of direct core build-up materials
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Girish Kumar
2015-01-01
Full Text Available Background and Objectives: The strength greatly influences the selection of core material because core must withstand forces due to mastication and para-function for many years. This study was conducted to evaluate certain mechanical properties of commonly used materials for direct core build-up, including visible light cured composite, polyacid modified composite, resin modified glass ionomer, high copper amalgam, and silver cermet cement. Materials and Methods: All the materials were manipulated according to the manufacturer′s recommendations and standard test specimens were prepared. A universal testing machine at different cross-head speed was used to determine all the four mechanical properties. Mean compressive strength, diametral tensile strength, flexural strength, and elastic modulus with standard deviations were calculated. Multiple comparisons of the materials were also done. Results: Considerable differences in compressive strength, diametral tensile strength, and flexural strength were observed. Visible light cured composite showed relatively high compressive strength, diametral tensile strength, and flexural strength compared with the other tested materials. Amalgam showed the highest value for elastic modulus. Silver cermet showed less value for all the properties except for elastic modulus. Conclusions: Strength is one of the most important criteria for selection of a core material. Stronger materials better resist deformation and fracture provide more equitable stress distribution, greater stability, and greater probability of clinical success.
Cordeiro, Marcos R C; Ranjan, Ramanathan Sri; Cicek, Nazim
2011-12-01
Electromagnetic induction (EMI) has been used to map soil properties such as salinity and water content. The objective of this research is to use EMI to map the potential distribution of nutrients around beef cattle pens and to relate this distribution to major physiographic field features. Beef cattle farms in different physiographic locations were surveyed in Manitoba, Canada, using an EM-38 conductivity meter georeferenced with a GPS receiver. Samples were collected using a response surface design and analysed for electrical conductivity (ECe), which was used as a proxy for determining potential build-up of nutrients. Multiple linear regression models (MLR) were used for calibration of the EM readings. The results showed that areas 1 through 4 had ECe soil layer to accumulate the nutrients. Micro-depressions played a major role in salt accumulation, with the depressions corresponding to higher values of ECe. The presence of features such as drainage ditches and compacted soils beneath roads strongly affected the direction of the plumes. Based on these results, the location of the pens on high elevations and the provision to collect the run-off from the pens were identified as good design criteria. Highly permeable soils may require a low permeability liner to capture the deep percolation and redirect it towards a collection area.
Young and embedded clusters in Cygnus-X: evidence for building up the initial mass function?
Maia, F. F. S.; Moraux, E.; Joncour, I.
2016-05-01
We provide a new view on the Cygnus-X north complex by accessing for the first time the low mass content of young stellar populations in the region. Canada-France-Hawaii Telescope/Wide-Field Infrared Camera was used to perform a deep near-infrared survey of this complex, sampling stellar masses down to ˜0.1 M⊙. Several analysis tools, including a extinction treatment developed in this work, were employed to identify and uniformly characterize a dozen unstudied young star clusters in the area. Investigation of their mass distributions in low-mass domain revealed a relatively uniform log-normal initial mass function (IMF) with a characteristic mass of 0.32 ± 0.08 M⊙ and mass dispersion of 0.40 ± 0.06. In the high-mass regime, their derived slopes showed that while the youngest clusters (age build up' their IMF by accreting low-mass stars formed in their vicinity during their first ˜3 Myr, before the gas expulsion phase, emerging at the age of ˜4 Myr with a fully fledged IMF. Finally, the derived distances to these clusters confirmed the existence of at least three different star-forming regions throughout Cygnus-X north complex, at distances of 500-900 pc, 1.4-1.7 and 3.0 kpc, and revealed evidence of a possible interaction between some of these stellar populations and the Cygnus OB2 association.
Comparative study of mechanical properties of direct core build-up materials.
Kumar, Girish; Shivrayan, Amit
2015-01-01
The strength greatly influences the selection of core material because core must withstand forces due to mastication and para-function for many years. This study was conducted to evaluate certain mechanical properties of commonly used materials for direct core build-up, including visible light cured composite, polyacid modified composite, resin modified glass ionomer, high copper amalgam, and silver cermet cement. All the materials were manipulated according to the manufacturer's recommendations and standard test specimens were prepared. A universal testing machine at different cross-head speed was used to determine all the four mechanical properties. Mean compressive strength, diametral tensile strength, flexural strength, and elastic modulus with standard deviations were calculated. Multiple comparisons of the materials were also done. Considerable differences in compressive strength, diametral tensile strength, and flexural strength were observed. Visible light cured composite showed relatively high compressive strength, diametral tensile strength, and flexural strength compared with the other tested materials. Amalgam showed the highest value for elastic modulus. Silver cermet showed less value for all the properties except for elastic modulus. Strength is one of the most important criteria for selection of a core material. Stronger materials better resist deformation and fracture provide more equitable stress distribution, greater stability, and greater probability of clinical success.
The Build-up of the Colour-Magnitude Relation as a Function of Environment
Tanaka, M; Arimoto, N; Okamura, S; Umetsu, K; Shimasaku, K; Tanaka, I; Yamada, T; Tanaka, Masayuki; Kodama, Tadayuki; Arimoto, Nobuo; Okamura, Sadanori; Umetsu, Keiichi; Shimasaku, Kazuhiro; Tanaka, Ichi; Yamada, Toru
2005-01-01
We discuss the environmental dependence of galaxy evolution based on deep panoramic imaging of two distant clusters taken with Suprime-Cam as part of the PISCES project. By combining with the SDSS data as a local counterpart for comparison, we construct a large sample of galaxies that spans wide ranges in environment, time, and stellar mass (or luminosity). We find that colours of galaxies, especially those of faint galaxies ($M_V>M_V^*+1$), change from blue to red at a break density as we go to denser regions. Based on local and global densities of galaxies, we classify three environments: field, groups, and clusters. We show that the cluster colour-magnitude relation is already built at $z=0.83$. In contrast to this, the bright-end of the field colour-magnitude relation has been vigorously built all the way down to the present-day and the build-up at the faint-end has not started yet. A possible interpretation of these results is that galaxies evolve in the 'down-sizing' fashion. That is, massive galaxies c...
An automated classification approach to ranking photospheric proxies of magnetic energy build-up
Al-Ghraibah, Amani; McAteer, R T James
2015-01-01
We study the photospheric magnetic field of ~2000 active regions in solar cycle 23 to search for parameters indicative of energy build-up and subsequent release as a solar flare. We extract three sets of parameters: snapshots in space and time- total flux, magnetic gradients, and neutral lines; evolution in time- flux evolution; structures at multiple size scales- wavelet analysis. This combines pattern recognition and classification techniques via a relevance vector machine to determine whether a region will flare. We consider classification performance using all 38 extracted features and several feature subsets. Classification performance is quantified using both the true positive rate and the true negative rate. Additionally, we compute the true skill score which provides an equal weighting to true positive rate and true negative rate and the Heidke skill score to allow comparison to other flare forecasting work. We obtain a true skill score of ~0.5 for any predictive time window in the range 2-24hr, with ...
Koivunoro, H; Hyvönen, H; Uusi-Simola, J; Jokelainen, I; Kosunen, A; Kortesniemi, M; Seppälä, T; Auterinen, I; Savolainen, S
2011-12-01
Magnesium-walled argon gas flow ionization chamber (Mg(Ar)) is used for photon dose measurements in the epithermal neutron beam of FiR 1 reactor in Finland. In this study, the photon dose measurements were re-evaluated against calculations applying a new chamber calibration factor defined in water instead of in air. Also, effect of the build-up cap on the measurements was investigated. The new calibration factor provides improved agreement between measured and calculated photon dose. Use of the build-up cap does not affect the measured signal in water in neutron beam.
Energy Technology Data Exchange (ETDEWEB)
Koivunoro, H., E-mail: hanna.koivunoro@helsinki.fi [Boneca Corporation, FI-00290 Helsinki (Finland)] [Department of Physics, P.O.B. 64, FI-00014 University of Helsinki (Finland)] [Department of Oncology, Helsinki University Central Hospital, P.O.B. 180, 00029 HUS (Finland); Hyvoenen, H. [Boneca Corporation, FI-00290 Helsinki (Finland); Uusi-Simola, J. [HUS Helsinki Medical Imaging Center, University of Helsinki (Finland); Jokelainen, I.; Kosunen, A. [Radiation Metrology Laboratory, Radiation and Nuclear Safety Authority-STUK, FI-00881 (Finland); Kortesniemi, M. [HUS Helsinki Medical Imaging Center, University of Helsinki (Finland); Seppaelae, T. [Department of Oncology, Helsinki University Central Hospital, P.O.B. 180, 00029 HUS (Finland); Auterinen, I. [VTT Technical Research Centre of Finland, Espoo (Finland); Savolainen, S. [Department of Physics, P.O.B. 64, FI-00014 University of Helsinki (Finland)] [HUS Helsinki Medical Imaging Center, University of Helsinki (Finland)
2011-12-15
Magnesium-walled argon gas flow ionization chamber (Mg(Ar)) is used for photon dose measurements in the epithermal neutron beam of FiR 1 reactor in Finland. In this study, the photon dose measurements were re-evaluated against calculations applying a new chamber calibration factor defined in water instead of in air. Also, effect of the build-up cap on the measurements was investigated. The new calibration factor provides improved agreement between measured and calculated photon dose. Use of the build-up cap does not affect the measured signal in water in neutron beam.
Early-time solution of the horizontal unconfined aquifer in the build-up phase
Gravanis, Elias; Akylas, Evangelos
2017-04-01
The Boussinesq equation is a dynamical equation for the free surface of saturated subsurface flows over an impervious bed. Boussinesq equation is non-linear. The non-linearity comes from the reduction of the dimensionality of the problem: The flow is assumed to be vertically homogeneous, therefore the flow rate through a cross section of the flow is proportional to the free surface height times the hydraulic gradient, which is assumed to be equal to the slope of the free surface (Dupuit approximation). In general, 'vertically' means normally on the bed; combining the Dupuit approximation with the continuity equation leads to the Boussinesq equation. There are very few transient exact solutions. Self- similar solutions have been constructed in the past by various authors. A power series type of solution was derived for a self-similar Boussinesq equation by Barenblatt in 1990. That type of solution has generated a certain amount of literature. For the unconfined flow case for zero recharge rate Boussinesq derived for the horizontal aquifer an exact solution assuming separation of variables. This is actually an exact asymptotic solution of the horizontal aquifer recession phase for late times. The kinematic wave is an interesting solution obtained by dropping the non-linear term in the Boussinesq equation. Although it is an approximate solution, and holds well only for small values of the Henderson and Wooding λ parameter (that is, for steep slopes, high conductivity or small recharge rate), it becomes less and less approximate for smaller values of the parameter, that is, it is asymptotically exact with respect to that parameter. In the present work we consider the case of the unconfined subsurface flow over horizontal bed in the build-up phase under constant recharge rate. This is a case with an infinite Henderson and Wooding parameter, that is, it is the limiting case where the non-linear term is present in the Boussinesq while the linear spatial derivative term
Directory of Open Access Journals (Sweden)
Himanshu Duhan
2015-01-01
Full Text Available Background: This study was designed to compare the clinical performance of composite, strip crowns, biological restoration, and composite with stainless steel band when used for the coronal build-up of anterior teeth. Materials and Methods: A total of 20 patients aged 3-6 years presenting with mutilated primary anterior teeth due to caries or trauma were selected for the study using randomized simple sampling. A total of 52 primary anterior teeth were randomly divided into four equal groups having 13 teeth in each group. Teeth in Group I were restored with composite, in Group II with strip crowns, in Group III with biologic restoration and with stainless steel band reinforced composite in group IV. The restorations were evaluated for color match, retention, surface texture, and anatomic form according to Ryge′s Direct (US Public Health Service evaluation criteria at baseline (immediate postoperative, after 48 h, 3, 6, and 9 months. The data obtained were statistically analyzed using Chi-square test, and level of significance, that is, P value was determined. Results: At baseline, none of the groups showed any color changes. Other than Group III all other groups showed highly significant changes (P 0.05. Deterioration in surface texture was exhibited maximum by restorations in Group IV followed by Group I at 3 months. Whereas, no surface changes were seen in Group II and III. Only Group I and IV showed discontinuity in anatomic form after 3 months. After 6 months, except in Group II, discontinuity in anatomic form was observed in all the groups. Discontinuity in anatomic form was seen in all the 4 groups after 9 months although the difference was not significant (P > 0.05. Conclusion: Biological restoration was found to be most satisfying esthetically owing to color compatibility with the patient′s tooth. Thus, it has a great potential to be used as esthetic restorative option in primary anteriors.
Duhan, Himanshu; Pandit, Inder Kumar; Srivastava, Nikhil; Gugnani, Neeraj; Gupta, Monika; Kochhar, Gulsheen Kaur
2015-01-01
Background: This study was designed to compare the clinical performance of composite, strip crowns, biological restoration, and composite with stainless steel band when used for the coronal build-up of anterior teeth. Materials and Methods: A total of 20 patients aged 3-6 years presenting with mutilated primary anterior teeth due to caries or trauma were selected for the study using randomized simple sampling. A total of 52 primary anterior teeth were randomly divided into four equal groups having 13 teeth in each group. Teeth in Group I were restored with composite, in Group II with strip crowns, in Group III with biologic restoration and with stainless steel band reinforced composite in group IV. The restorations were evaluated for color match, retention, surface texture, and anatomic form according to Ryge's Direct (US Public Health Service) evaluation criteria at baseline (immediate postoperative), after 48 h, 3, 6, and 9 months. The data obtained were statistically analyzed using Chi-square test, and level of significance, that is, P value was determined. Results: At baseline, none of the groups showed any color changes. Other than Group III all other groups showed highly significant changes (P 0.05). Deterioration in surface texture was exhibited maximum by restorations in Group IV followed by Group I at 3 months. Whereas, no surface changes were seen in Group II and III. Only Group I and IV showed discontinuity in anatomic form after 3 months. After 6 months, except in Group II, discontinuity in anatomic form was observed in all the groups. Discontinuity in anatomic form was seen in all the 4 groups after 9 months although the difference was not significant (P > 0.05). Conclusion: Biological restoration was found to be most satisfying esthetically owing to color compatibility with the patient's tooth. Thus, it has a great potential to be used as esthetic restorative option in primary anteriors. PMID:26759595
The Argo simulation - II. The early build-up of the Hubble sequence
Fiacconi, Davide; Feldmann, Robert; Mayer, Lucio
2015-01-01
The Hubble sequence is a common classification scheme for the structure of galaxies. Despite the tremendous usefulness of this diagnostic, we still do not fully understand when, where, and how this morphological ordering was put in place. Here, we investigate the morphological evolution of a sample of 22 high-redshift (z ≥ 3) galaxies extracted from the Argo simulation. Argo is a cosmological zoom-in simulation of a group-sized halo and its environment. It adopts the same high-resolution (˜104 M⊙, ˜100 pc) and sub-grid physical model that was used in the Eris simulation but probes a sub-volume almost 10 times bigger with as many as 45 million gas and star particles in the zoom-in region. Argo follows the early assembly of galaxies with a broad range of stellar masses (log M⋆/M⊙ ˜ 8-11 at z ≃ 3), while resolving properly their structural properties. We recover a diversity of morphologies, including late-type/irregular disc galaxies with flat rotation curves, spheroid dominated early-type discs, and a massive elliptical galaxy, already established at z ˜ 3. We identify major mergers as the main trigger for the formation of bulges and the steepening of the circular velocity curves. Minor mergers and non-axisymmetric perturbations (stellar bars) drive the bulge growth in some cases. The specific angular momenta of the simulated disc components fairly match the values inferred from nearby galaxies of similar M⋆ once the expected redshift evolution of disc sizes is accounted for. We conclude that morphological transformations of high-redshift galaxies of intermediate mass are likely triggered by processes similar to those at low redshift and result in an early build-up of the Hubble sequence.
The Effect of Cyclic Loading on the Compressive Strength of Core Build-Up Materials.
Zankuli, Muayed A; Silikas, Nick; Devlin, Hugh
2015-01-15
To evaluate the effect of cyclic loading on compressive strength of core build-up materials. Four dual-cured composites (Core.X Flow, Grandio Core, Bright Flow Core, Spee-Dee) and one light-cured reinforced resin-modified glass ionomer (Fuji II LC) were tested. One hundred cylindrical specimens (4 mm × 6 mm) were prepared. Each material had two groups (ten specimens to be tested under static loading and ten specimens to be tested after cyclic loading). The specimens were stored wet, and after 30 days, one group of each material was cyclically loaded (for 250,000 cycles with a frequency of 1.6 Hz under stress load of 68.6 N) in a chewing simulator CS-4.2. Then specimens were subjected to static compressive loading until failure in a universal testing machine. Mean compressive strength values before cycling ranged from 144 MPa (15.8) for Fuji II LC to 277 MPa (23.2) for Grandio Core. Independent t-test showed no statistically significant difference (p > 0.05) in the compressive strength of each material before and after cycling (p = 0.7 Grandio Core, p = 0.3 Core.X Flow, p = 0.6 Bright Flow Core, p = 0.2 Spee-Dee, p = 0.6 Fuji II LC); however, there was a statistically significant difference between the materials when comparing before and after cycling. All tested materials showed no reduction in the compressive strength after cycling. Therefore, the tested materials can survive 1 year in service without a reduction in compressive strength. © 2015 by the American College of Prosthodontists.
Duhan, Himanshu; Pandit, Inder Kumar; Srivastava, Nikhil; Gugnani, Neeraj; Gupta, Monika; Kochhar, Gulsheen Kaur
2015-01-01
This study was designed to compare the clinical performance of composite, strip crowns, biological restoration, and composite with stainless steel band when used for the coronal build-up of anterior teeth. A total of 20 patients aged 3-6 years presenting with mutilated primary anterior teeth due to caries or trauma were selected for the study using randomized simple sampling. A total of 52 primary anterior teeth were randomly divided into four equal groups having 13 teeth in each group. Teeth in Group I were restored with composite, in Group II with strip crowns, in Group III with biologic restoration and with stainless steel band reinforced composite in group IV. The restorations were evaluated for color match, retention, surface texture, and anatomic form according to Ryge's Direct (US Public Health Service) evaluation criteria at baseline (immediate postoperative), after 48 h, 3, 6, and 9 months. The data obtained were statistically analyzed using Chi-square test, and level of significance, that is, P value was determined. At baseline, none of the groups showed any color changes. Other than Group III all other groups showed highly significant changes (P 0.05). Deterioration in surface texture was exhibited maximum by restorations in Group IV followed by Group I at 3 months. Whereas, no surface changes were seen in Group II and III. Only Group I and IV showed discontinuity in anatomic form after 3 months. After 6 months, except in Group II, discontinuity in anatomic form was observed in all the groups. Discontinuity in anatomic form was seen in all the 4 groups after 9 months although the difference was not significant (P > 0.05). Biological restoration was found to be most satisfying esthetically owing to color compatibility with the patient's tooth. Thus, it has a great potential to be used as esthetic restorative option in primary anteriors.
How does the interaction between spelling and motor processes build up during writing acquisition?
Kandel, Sonia; Perret, Cyril
2015-03-01
How do we recall a word's spelling? How do we produce the movements to form the letters of a word? Writing involves several processing levels. Surprisingly, researchers have focused either on spelling or motor production. However, these processes interact and cannot be studied separately. Spelling processes cascade into movement production. For example, in French, producing letters PAR in the orthographically irregular word PARFUM (perfume) delays motor production with respect to the same letters in the regular word PARDON (pardon). Orthographic regularity refers to the possibility of spelling a word correctly by applying the most frequent sound-letter conversion rules. The present study examined how the interaction between spelling and motor processing builds up during writing acquisition. French 8-10 year old children participated in the experiment. This is the age handwriting skills start to become automatic. The children wrote regular and irregular words that could be frequent or infrequent. They wrote on a digitizer so we could collect data on latency, movement duration and fluency. The results revealed that the interaction between spelling and motor processing was present already at age 8. It became more adult-like at ages 9 and 10. Before starting to write, processing irregular words took longer than regular words. This processing load spread into movement production. It increased writing duration and rendered the movements more dysfluent. Word frequency affected latencies and cascaded into production. It modulated writing duration but not movement fluency. Writing infrequent words took longer than frequent words. The data suggests that orthographic regularity has a stronger impact on writing than word frequency. They do not cascade in the same extent. Copyright © 2014 Elsevier B.V. All rights reserved.
Chisolm, Eric
2012-01-01
This is an introduction to geometric algebra, an alternative to traditional vector algebra that expands on it in two ways: 1. In addition to scalars and vectors, it defines new objects representing subspaces of any dimension. 2. It defines a product that's strongly motivated by geometry and can be taken between any two objects. For example, the product of two vectors taken in a certain way represents their common plane. This system was invented by William Clifford and is more commonly known as Clifford algebra. It's actually older than the vector algebra that we use today (due to Gibbs) and includes it as a subset. Over the years, various parts of Clifford algebra have been reinvented independently by many people who found they needed it, often not realizing that all those parts belonged in one system. This suggests that Clifford had the right idea, and that geometric algebra, not the reduced version we use today, deserves to be the standard "vector algebra." My goal in these notes is to describe geometric al...
Bidimensionality and Geometric Graphs
Fomin, Fedor V; Saurabh, Saket
2011-01-01
In this paper we use several of the key ideas from Bidimensionality to give a new generic approach to design EPTASs and subexponential time parameterized algorithms for problems on classes of graphs which are not minor closed, but instead exhibit a geometric structure. In particular we present EPTASs and subexponential time parameterized algorithms for Feedback Vertex Set, Vertex Cover, Connected Vertex Cover, Diamond Hitting Set, on map graphs and unit disk graphs, and for Cycle Packing and Minimum-Vertex Feedback Edge Set on unit disk graphs. Our results are based on the recent decomposition theorems proved by Fomin et al [SODA 2011], and our algorithms work directly on the input graph. Thus it is not necessary to compute the geometric representations of the input graph. To the best of our knowledge, these results are previously unknown, with the exception of the EPTAS and a subexponential time parameterized algorithm on unit disk graphs for Vertex Cover, which were obtained by Marx [ESA 2005] and Alber and...
Energy Technology Data Exchange (ETDEWEB)
Kazumata, Ken; Kuroda, Satoshi; Houkin, Kiyohiro; Abe, Hiroshi [Hokkaido Univ., Sapporo (Japan). School of Medicine; Mitsumori, Kenji
1994-12-01
The re-build up phenomenon is the characteristic EEG finding following hyperventilation in childhood moyamoya disease. This study evaluated the role of cerebral blood flow (CBF) associated with this phenomenon using single photon emission CT (SPECT) with Tc-99m hexamethyl propylene amine oxime (Tc-99m HMPAO). The subjects were each two adult and pediatric patients. Tc-99m HMPAO (10 mCi) was injected immediately after 4-min hyperventilation. After the initial scanning, an additional 20 mCi of Tc-99m HMPAO was iv injected for the second scanning. Xe-133 SPECT was also performed for the evaluation of resting CBF. The re-build up phenomenon was observed preoperatively in one patient, which originated from the bilateral parieto-occipital area one min after hyperventilation and extended to the entire hemisphere 30 sec later. SPECT did not reveal severe ischemia in the entire hemisphere after hyperventilation, but revealed a marked CBF decrease in the bilateral parieto-occipital lobe. The patient underwent bilateral STA-MCA anastomosis combined with encephalo-duro-arterio-myo-synangiosis. Postoperative examination revealed no evidence of build-up phenomenon on EEG or abnormal perfusion reserve on Xe-133 SPECT. Nor was marked CBF decrease observed after hyperventilation on Tc-99m SPECT. These findings suggest that regional CBF decrease may play a critical role in the appearance of the re-build up phenomenon on EEG, as well as hypoxic hypoxia after hyperventilation. (N.K.).
Energy Technology Data Exchange (ETDEWEB)
Zhulidov, A.V.; Yemets, V.M.
1979-01-01
Lead in automobile exhaust gases gets deposited on and builds up in roadside soils, grasses, plants, trees, shrubs, mosses, and the bodies of birds and mammals. Insects, and particularly beetles, have not been studied in this respect. This gap is now filled by investigating the build-up of lead in the bodies of the beetles inhabiting these milieux. To this end, insects of 12 species were gathered from forested areas in neighborhood of a heavily traveled highway, along with samples of soil and vegetation. The lead content in all these samples was determined in the form of the colloidal ash of a sulfur compound. For comparison, beetles of 5 species gathered in the same area during 1930 to 1939 were also analyzed. The build-up of lead in the beetles was markedly higher than in the soil and vegetation samples. The lead content of the beetles varied depending on species: the soil-infesting beetles (Carabidae) contained much more lead in their bodies than the plant infesting beetles such as the Scarabeidae, the Buprestidae, and the Cerambycidae. Compared with the beetles collected during 1930 to 1939, the beetles collected in 1975 in the Voronezh Natural Preserve (through which the highway runs) display a much higher lead content. The build-up of lead in beetle bodies can be used as an index of environmental pollution to monitor the state of roadside ecosystems. This is particularly important for natural preserves on which, in general, heavy motor vehicle traffic is not justified.
DEFF Research Database (Denmark)
Conseil, Helene; Gudla, Visweswara Chakravarthy; Jellesen, Morten Stendahl
2016-01-01
, thermal mass, and port/opening size. The effect of the internal humidity build-up on corrosion reliability has been evaluated by measuring the leakage current (LC) on interdigitated test comb patterns, which are precontaminated with sodium chloride and placed inside the enclosure. The results showed...
A comprehensive interpretation of the NEEM basal ice build-up using a multi parametric approach
Directory of Open Access Journals (Sweden)
T. Goossens
2015-10-01
propose a first interpretative framework for the build-up of the NEEM basal ice sequence, based on the origin of the various ice types.
A comprehensive interpretation of the NEEM basal ice build-up using a multi parametric approach
Goossens, T.; Sapart, C. J.; Dahl-Jensen, D.; Popp, T.; El Amri, S.; Tison, J. L.
2015-10-01
interpretative framework for the build-up of the NEEM basal ice sequence, based on the origin of the various ice types.
Public health policy and the building up of a Brazilian medical identity.
de Castro-Santos, L A
2005-12-01
Since George Herbert Mead studied "the social self" and the interactionists went further in distinguishing "images of self", a lecture on the building up of a Brazilian medical identity should try to focus on the patterns of self-images, presented images, and aspired-to images among the Brazilian medical elites during the First Republic (1889-1930). In no other period of Brazilian history were those "images" of professional identity so close--in contrast, later periods of Brazilian history witnessed an almost permanent "collision" or the clashing of such images among public health specialists. Oswaldo Cruz, Carlos Chagas, Artur Neiva and Belisário Pena are perhaps the best examples of successful careers as "sanitarians" (to recall John Duffy's historical work on luminaries before and after the "New Public Health" in the United States), and as important political actors during Brazil's First Republic. In light of the prominent political, policy-oriented, and scientific roles public health professionals played in Brazil, it is interesting to suggest that in large part such prominence resulted from the symbolic impact of the ideologies of sanitary reform on the political agenda of that period of Brazilian history. Where many studies look for personal rivalries and disputes around Chagas and Neiva as public figures, we may also see the importance of finding identity-building processes among public health specialists as an integrated group (e.g., trying to appear as "significant others" for the new generations of medical graduates in the country), regardless of existing rivalries. Cruz and Chagas, especially, were names with great impact in the Brazilian press (pro and con), a circumstance made possible largely by their easy and direct access to the Brazilian presidents Rodrigues Alves and Epitácio Pessoa, and, most clearly, by public health being one of Brazil's political priorities to find a place among the "civilized nations" of the world. A task that further
Institute of Scientific and Technical Information of China (English)
林意; 刘杰
2014-01-01
蜡染几何图案是我国民间艺术，有着广泛的市场。在辅助几何图案设计系统中，需要对有关图案进行放大缩小，尤其是散点轮廓的放大缩小。由于散点式几何图案是由一些基本几何单元组成，以往基于图像像素的放大缩小算法不起作用。首先提取散点单元，把基本几何单元转化为点；然后针对散点式几何图案提出一种散点轮廓的优化提取散点算法；对提取的轮廓优化散点进行放大缩小；并应用B样条函数拟合散点式几何图案的轮廓，实现图案轮廓的矢量化放大缩小。实验表明该算法能有效缩放图案的散点轮廓，速度快，可靠性高，对凸凹区域都有效果，在纺织图案的设计、蜡染图案设计等领域具有实用价值。%Batik geometric pattern is a folk art in China,and has wide range of markets.In computer-aided geometric pattern design sys-tem,there has the need to zoom the geometric patterns,especially for the scatter contours.Since the geometric patterns with scattered points are composed of some basic geometric units,previous image pixels-based zooming algorithm can’t be applied.In the paper,we first extract the scatter units,and transform the basic geometric units into the points.Then we propose an optimised scattered point extraction algorithm for scatter contour aiming at the scatter geometric patterns,and zoom the extracted optimised contour scatter.And the B-spline function is used to fit the contour of the scatter geometric pattern,so that implements the vectorised zooming of pattern contour.Experiments show that this algo-rithm can effectively zoom the scatter contour of the pattern,it is quick in speed and high in reliability,and is effect in whatever the convex or concave regions,so it has the applied value in the fields of textile pattern design,batik pattern design and others.
Testing algebraic geometric codes
Institute of Scientific and Technical Information of China (English)
CHEN Hao
2009-01-01
Property testing was initially studied from various motivations in 1990's.A code C (∩)GF(r)n is locally testable if there is a randomized algorithm which can distinguish with high possibility the codewords from a vector essentially far from the code by only accessing a very small (typically constant) number of the vector's coordinates.The problem of testing codes was firstly studied by Blum,Luby and Rubinfeld and closely related to probabilistically checkable proofs (PCPs).How to characterize locally testable codes is a complex and challenge problem.The local tests have been studied for Reed-Solomon (RS),Reed-Muller (RM),cyclic,dual of BCH and the trace subcode of algebraicgeometric codes.In this paper we give testers for algebraic geometric codes with linear parameters (as functions of dimensions).We also give a moderate condition under which the family of algebraic geometric codes cannot be locally testable.
Testing algebraic geometric codes
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Property testing was initially studied from various motivations in 1990’s. A code C GF (r)n is locally testable if there is a randomized algorithm which can distinguish with high possibility the codewords from a vector essentially far from the code by only accessing a very small (typically constant) number of the vector’s coordinates. The problem of testing codes was firstly studied by Blum, Luby and Rubinfeld and closely related to probabilistically checkable proofs (PCPs). How to characterize locally testable codes is a complex and challenge problem. The local tests have been studied for Reed-Solomon (RS), Reed-Muller (RM), cyclic, dual of BCH and the trace subcode of algebraicgeometric codes. In this paper we give testers for algebraic geometric codes with linear parameters (as functions of dimensions). We also give a moderate condition under which the family of algebraic geometric codes cannot be locally testable.
Manwani, Naresh
2010-01-01
In this paper we present a new algorithm for learning oblique decision trees. Most of the current decision tree algorithms rely on impurity measures to assess the goodness of hyperplanes at each node while learning a decision tree in a top-down fashion. These impurity measures do not properly capture the geometric structures in the data. Motivated by this, our algorithm uses a strategy to assess the hyperplanes in such a way that the geometric structure in the data is taken into account. At each node of the decision tree, we find the clustering hyperplanes for both the classes and use their angle bisectors as the split rule at that node. We show through empirical studies that this idea leads to small decision trees and better performance. We also present some analysis to show that the angle bisectors of clustering hyperplanes that we use as the split rules at each node, are solutions of an interesting optimization problem and hence argue that this is a principled method of learning a decision tree.
Shimizu, Y; Tsujimoto, A; Furuichi, T; Suzuki, T; Tsubota, K; Miyazaki, M; Platt, J A
2015-01-01
We examined the influence of light intensity on surface free energy characteristics and dentin bond strength of dual-cure direct core build-up resin systems. Two commercially available dual-cure direct core build-up resin systems, Clearfil DC Core Automix with Clearfil Bond SE One and UniFil Core EM with Self-Etching Bond, were studied. Bovine mandibular incisors were mounted in acrylic resin and the facial dentin surfaces were wet ground on 600-grit silicon carbide paper. Adhesives were applied to dentin surfaces and cured with light intensities of 0 (no irradiation), 200, 400, and 600 mW/cm(2). The surface free energy of the adhesives (five samples per group) was determined by measuring the contact angles of three test liquids placed on the cured adhesives. To determine the strength of the dentin bond, the core build-up resin pastes were condensed into the mold on the adhesive-treated dentin surfaces according to the methods described for the surface free energy measurement. The resin pastes were cured with the same light intensities as those used for the adhesives. Ten specimens per group were stored in water maintained at 37°C for 24 hours, after which they were shear tested at a crosshead speed of 1.0 mm/minute in a universal testing machine. Two-way analysis of variance (ANOVA) and a Tukey-Kramer test were performed, with the significance level set at 0.05. The surface free energies of the adhesive-treated dentin surfaces decreased with an increase in the light intensity of the curing unit. Two-way ANOVA revealed that the type of core build-up system and the light intensity significantly influence the bond strength, although there was no significant interaction between the two factors. The highest bond strengths were achieved when the resin pastes were cured with the strongest light intensity for all the core build-up systems. When polymerized with a light intensity of 200 mW/cm(2) or less, significantly lower bond strengths were observed. CONClUSIONS: The
Understanding the build-up of supermassive black holes and galaxies
Carrera, Francisco; Ueda, Yoshihiro; Georgakakis, Antonis
2016-07-01
. The excellent survey capabilities of Athena/WFI (effective area, angular resolution, field of view) will allow to measure the incidence of feedback in the shape of warm absorbers and Ultra Fast Outflows among the general population of AGN, as well as to complete the census of black hole growth by detecting and characterising significant samples of the most heavily obscured (including Compton thick) AGN, to redshifts z~3-4. The outstanding spectral throughput and resolution of Athena/X-IFU will permit measuring the energetics of those outflows to assess their influence on their host galaxies. The demographics of the heavily obscured and outflowing populations relative to their hosts are fundamental for understanding how major black hole growth events relate to the build-up of galaxies.
Inbreeding and building up small populations of stingless bees (Hymenoptera, Apidae
Directory of Open Access Journals (Sweden)
Paulo Nogueira-Neto
2002-12-01
Full Text Available A study of the viability of small populations of Hymenoptera is a matter of importance to gain a better zoological, ethological, genetical and ecological knowledge of these insects, and for conservation purposes, mainly because of the consequences to the survival of colonies of many species of bees, wasps, and ants. Based on the Whiting (1943 principle, Kerr & Vencovski (1982 presented a hypothesis that states that viable populations of stingless bees (Meliponini should have at least 40 colonies to survive. This number was later extended to 44 colonies by Kerr (1985. This would be necessary to avoid any substantial amount of homozygosis in the pair of chromosomic sexual loci, by keeping at least six different sexual gene alleles in a reproductive population. In most cases this would prevent the production of useless diploid males. However, several facts weigh against considering this as a general rule. From 1990 to 2001, 287 colony divisions were made, starting with 28 foundation colonies, in the inbreeding and population experiments with the Meliponini reported here. These experiments constitute the most extensive and longest scientific research ever made with Meliponini bees. In ten different experiments presented here, seven species (one with two subspecies of Meliponini bees were inbred in five localities inside their wide-reaching native habitats, and in two localities far away from these habitats. This was done for several years. On the whole, the number of colonies increased and the loss of colonies over the years was small. In two of these experiments, although these populations were far (1,000 km and 1,200 km from their native habitat, their foundation colonies were multiplied successfuly. It was possible to build up seven strong and three expanding medium populations, starting with one, two, three or even five colonies. However, in six other cases examined here, the Whiting (1943 principle and the hypothesis of Kerr & Vencovski (1982
Corrochano, Eduardo Bayro
2010-01-01
This book presents contributions from a global selection of experts in the field. This useful text offers new insights and solutions for the development of theorems, algorithms and advanced methods for real-time applications across a range of disciplines. Written in an accessible style, the discussion of all applications is enhanced by the inclusion of numerous examples, figures and experimental analysis. Features: provides a thorough discussion of several tasks for image processing, pattern recognition, computer vision, robotics and computer graphics using the geometric algebra framework; int
Luo, Wenhai; Phan, Hop V; Hai, Faisal I; Price, William E; Guo, Wenshan; Ngo, Hao H; Yamamoto, Kazuo; Nghiem, Long D
2016-01-01
This study investigated the effects of salinity increase on bacterial community structure in a membrane bioreactor (MBR) for wastewater treatment. The influent salt loading was increased gradually to simulate salinity build-up in the bioreactor during the operation of a high retention-membrane bioreactor (HR-MBR). Bacterial community diversity and structure were analyzed using 454 pyrosequencing of 16S rRNA genes of MBR mixed liquor samples. Results show that salinity increase reduced biological performance but did not affect microbial diversity in the bioreactor. Unweighted UniFrac and taxonomic analyses were conducted to relate the reduced biological performance to the change of bacterial community structure. In response to the elevated salinity condition, the succession of halophobic bacteria by halotolerant/halophilic microbes occurred and thereby the biological performance of MBR was recovered. These results suggest that salinity build-up during HR-MBR operation could be managed by allowing for the proliferation of halotolerant/halophilic bacteria.
Institute of Scientific and Technical Information of China (English)
DARBAN Daim Ali; PATHAN Mumtaz Ali; BHATTI Abdul Ghaffar; MAITELO Sultan Ahmed
2005-01-01
Pasteuria penetrans will build-up faster where there is a high initial nematode density and can suppress root-knot nematode populations in the roots of tomato plants. The effect of different initial densities of nematode (Meloidogyne javanica)(150, 750, 1500, 3000) and P. penetrans infected females (F1, F3) densities (F0=control and AC=absolute control without nematode or P. penetrans inoculum) on the build-up of Pasteuria population was investigated over four crop cycles. Two major points of interest were highlighted. First, that within a confined soil volume, densities of P. penetrans can increase >100 times within 2 or 3 crop cycles. Second, from a relatively small amount of spore inoculum, infection of the host is very high. There were more infected females in the higher P. penetrans doses. The root growth data confirms the greater number of females in the controls particularly at the higher inoculum densities in the third and fourth crops. P. penetrans generally caused the fresh root weights to be higher than those in the control. P. penetrans has shown greater reduction of egg masses per plant at most densities.The effects of different initial densities of M. javanica and P. penetrans on the development of the pest and parasite populations were monitored. And no attempt was made to return the P. penetrans spores to the pots after each crop so the build-up in actual numbers of infected females and spores under natural conditions may be underestimated.
Institute of Scientific and Technical Information of China (English)
程小军; 崔祜涛; 崔平远; 徐瑞
2011-01-01
针对航天器带有非凸几何约束以及输入有界的问题,提出了一种姿态机动预测控制算法.分析了姿态机动所受到的几何约束,并对非凸二次形式约束及其Hesse矩阵进行研究,证明了该约束的非凸性.通过对正定Hesse矩阵的构造,给出非凸约束凸化映射关系.最后给出姿态机动预测控制律,解决了由于姿态机动过程中非凸约束造成的全局解收敛困难以及路径安全性问题.数值仿真结果显示该算法不仅能在大范围内得到优化姿态路径,同时满足所有约束.%A predictive control algorithm is presented in this paper for spacecraft attitude maneuver with nonconvex geometric constraint and bounded inputs. The nonconvex property of the geometric constraint is proved based on the analysis of its Hessian matrix. Then the transformation from nonconvex constraint to convex one is presented by constructing positive definite Hessian matrix. Consequently, a predictive control algorithm for spacecraft attitude maneuver is presented, and it can readily obtain global solution , as well as to solve the safety problem. The simulation results show that the presented algorithm can achieve optimal attitude path and satisfy all constraints.
The global build-up to intrinsic ELM bursts and comparison with pellet triggered ELMs seen in JET
Chapman, S. C.; Dendy, R. O.; Lang, P. T.; Watkins, N. W.; Calderon, F. A.; Romanelli, M.; Todd, T. N.; Contributors, JET
2017-02-01
We focus on JET plasmas in which ELMs are triggered by pellets in the presence of ELMs which occur naturally. We perform direct time domain analysis of signals from fast radial field coils and toroidal full flux azimuthal loops. These toroidally integrating signals provide simultaneous high time resolution measurements of global plasma dynamics and its coupling to the control system. We examine the time dynamics of these signals in plasmas where pellet injection is used to trigger ELMs in the presence of naturally occurring ELMs. Pellets whose size and speed are intended to provide maximum local perturbation for ELM triggering are launched at pre-programmed times, without correlation to the occurrence times of intrinsic ELMs. Pellet rates were sufficiently low to prevent sustained changes of the underlying plasma conditions and natural ELM behaviour. We find a global signature of the build-up to natural ELMs in the temporal analytic phase of both the full flux loops and fast radial field coil signals. Before a natural ELM, the signal phases align to the same value on a ˜ 2-5 ms timescale. This global build up to a natural ELM occurs whilst the amplitude of the full flux loop and fast radial field coil signals are at their background value: it precedes the response seen in these signals to the onset of ELMing. In contrast these signals do not clearly phase align before the ELM for ELMs which are the first to occur following pellet injection. This provides a direct test that can distinguish when an ELM is triggered by a pellet as opposed to occurring naturally. It further supports the idea [1-4] of a global build up phase that precedes natural ELMs; pellets can trigger ELMs even when the signal phase is at a value when a natural ELM is unlikely to occur.
On scale and magnitude of pressure build-up induced by large-scale geologic storage of CO2
Energy Technology Data Exchange (ETDEWEB)
Zhou, Q.; Birkholzer, J. T.
2011-05-01
The scale and magnitude of pressure perturbation and brine migration induced by geologic carbon sequestration is discussed assuming a full-scale deployment scenario in which enough CO{sub 2} is captured and stored to make relevant contributions to global climate change mitigation. In this scenario, the volumetric rates and cumulative volumes of CO{sub 2} injection would be comparable to or higher than those related to existing deep-subsurface injection and extraction activities, such as oil production. Large-scale pressure build-up in response to the injection may limit the dynamic storage capacity of suitable formations, because over-pressurization may fracture the caprock, may drive CO{sub 2}/brine leakage through localized pathways, and may cause induced seismicity. On the other hand, laterally extensive sedimentary basins may be less affected by such limitations because (i) local pressure effects are moderated by pressure propagation and brine displacement into regions far away from the CO{sub 2} storage domain; and (ii) diffuse and/or localized brine migration into overlying and underlying formations allows for pressure bleed-off in the vertical direction. A quick analytical estimate of the extent of pressure build-up induced by industrial-scale CO{sub 2} storage projects is presented. Also discussed are pressure perturbation and attenuation effects simulated for two representative sedimentary basins in the USA: the laterally extensive Illinois Basin and the partially compartmentalized southern San Joaquin Basin in California. These studies show that the limiting effect of pressure build-up on dynamic storage capacity is not as significant as suggested by Ehlig-Economides and Economides, who considered closed systems without any attenuation effects.
Symplectic algebraic dynamics algorithm
Institute of Scientific and Technical Information of China (English)
2007-01-01
Based on the algebraic dynamics solution of ordinary differential equations andintegration of ,the symplectic algebraic dynamics algorithm sn is designed,which preserves the local symplectic geometric structure of a Hamiltonian systemand possesses the same precision of the na ve algebraic dynamics algorithm n.Computer experiments for the 4th order algorithms are made for five test modelsand the numerical results are compared with the conventional symplectic geometric algorithm,indicating that sn has higher precision,the algorithm-inducedphase shift of the conventional symplectic geometric algorithm can be reduced,and the dynamical fidelity can be improved by one order of magnitude.
Simulation of Electron-Cloud Build-Up for the Cold Arcs of the LHC and Comparison with Measured Data
Maury Cuna, H; Rumolo, G; Tavian, L; Zimmermann, F
2011-01-01
The electron cloud generated by synchrotron radiation or residual gas ionization is a concern for LHC operation and performance. We report the results of simulations studies which examine the electron cloud build-up, at injection energy, 3.5 TeV for various operation parameters. In particular, we determine the value of the secondary emission yield corresponding to the multipacting threshold, and investigate the electron density, and heat as a function of bunch intensity for dipoles and field-free regions. We also include a comparison between simulations results and measured heat-load data from the LHC scrubbing runs in 2011.
Hazra, Gopal; Choudhuri, Arnab Rai; Miesch, Mark S.
2017-01-01
We develop a three-dimensional kinematic self-sustaining model of the solar dynamo in which the poloidal field generation is from tilted bipolar sunspot pairs placed on the solar surface above regions of strong toroidal field by using the SpotMaker algorithm, and then the transport of this poloidal field to the tachocline is primarily caused by turbulent diffusion. We obtain a dipolar solution within a certain range of parameters. We use this model to study the build-up of the polar magnetic field and show that some insights obtained from surface flux transport models have to be revised. We present results obtained by putting a single bipolar sunspot pair in a hemisphere and two symmetrical sunspot pairs in two hemispheres. We find that the polar fields produced by them disappear due to the upward advection of poloidal flux at low latitudes, which emerges as oppositely signed radial flux and which is then advected poleward by the meridional flow. We also study the effect that a large sunspot pair, violating Hale’s polarity law, would have on the polar field. We find that there would be some effect—especially if the anti-Hale pair appears at high latitudes in the mid-phase of the cycle—though the effect is not very dramatic.
Hazra, Gopal; Miesch, Mark S
2016-01-01
We develop a three-dimensional kinematic self-sustaining model of the solar dynamo in which the poloidal field generation is from tilted bipolar sunspot pairs placed on the solar surface above regions of strong toroidal field by using the SpotMaker algorithm and then the transport of this poloidal field to the tachocline is primarily caused by turbulent diffusion. We obtain a dipolar solution within a certain range of parameters. We use this model to study the build-up of the polar magnetic field and show that some insights obtained from surface flux transport (SFT) models have to be revised. We present results obtained by putting a single bipolar sunspot pair in a hemisphere and two symmetrical sunspot pairs in two hemispheres. We find that the polar fields produced by them disappear due to subduction by the meridional circulation sinking underneath the surface in the polar region, which is not included in the SFT models. We also study the effect that a large sunspot pair violating Hale's polarity law would ...
Height and Tilt Geometric Texture
DEFF Research Database (Denmark)
Andersen, Vedrana; Desbrun, Mathieu; Bærentzen, Jakob Andreas
2009-01-01
We propose a new intrinsic representation of geometric texture over triangle meshes. Our approach extends the conventional height field texture representation by incorporating displacements in the tangential plane in the form of a normal tilt. This texture representation offers a good practical...... compromise between functionality and simplicity: it can efficiently handle and process geometric texture too complex to be represented as a height field, without having recourse to full blown mesh editing algorithms. The height-and-tilt representation proposed here is fully intrinsic to the mesh, making...
DEFF Research Database (Denmark)
Fogliata, Antonella; Vanetti, Eugenio; Albers, Dirk
2007-01-01
with modified Batho correction; Nucletron Helax-TMS: the collapsed cone and the pencil beam with equivalent path length correction; CMS XiO: the multigrid superposition and the fast Fourier transform convolution; Philips Pinnacle: the collapsed cone. Monte Carlo simulations (MC) performed with the EGSnrc codes...... BEAMnrc and DOSxyznrc from NRCC in Ottawa were used as a benchmark. The study was carried out in simple geometrical water phantoms (rho = 1.00 g cm(-3)) with inserts of different densities simulating light lung tissue (rho = 0.035 g cm(-3)), normal lung (rho = 0.20 g cm(-3)) and cortical bone tissue (rho...... = 1.80 g cm(-3)). Experiments were performed for low- and high-energy photon beams (6 and 15 MV) and for square (13 x 13 cm2) and elongated rectangular (2.8 x 13 cm2) fields. Analysis was carried out on the basis of depth dose curves and transverse profiles at several depths. Assuming the MC data...
基于对象的抗几何攻击的视频水印算法%Object Based Watermarking Algorithm Robust to Geometric Transformation Attacks
Institute of Scientific and Technical Information of China (English)
谌志鹏; 邹建成
2012-01-01
MPEG-4标准中基于对象的编码方法具有较好的交互性、可存取性,同时也带来了版权保护的问题.为此,提出一种基于对象的水印算法,该算法使得视频对象从一个视频序列被移动到另一个序列中,仍然能正确提取出水印.该算法通过Radon变换校正视频对象的旋转角度和缩放尺度,将水印嵌入到SA -DCT域中的部分系数中.实验结果表明,该算法能够和MPEG-4编码器有机整合、失真小,能抵抗旋转、缩放等几何攻击.%One of the key points of the MPEG-4 standard is the possibility to access and manipulate objects within a video sequence, but it increases the demand for information security protection and multimedia authentication technologies. An object based watermarking algorithm is proposed, which can correctly access the data embedded in the object. To resist against scaling and rotation attacks, two generalized Radon transformations are used. The watermark is embedded in the quantized SA-DCT coefficients. Experiments show that the algorithm is low-distortion, robust to geometry transformation attacks. And the algorithm can integrate with the MPEG-4 codec very well.
The global build-up to intrinsic ELM bursts seen in divertor full flux loops in Jet
Chapman, S C; Todd, T N; Watkins, N W; Calderon, F A; Morris, J; Contributors, JET
2015-01-01
A global signature of the build-up to an intrinsic ELM is found in the phase of signals measured in full flux azimuthal loops in the divertor region of JET. Full flux loop signals provide a global measurement proportional to the voltage induced by changes in poloidal magnetic flux; they are electromagnetically induced by the dynamics of spatially integrated current density. We perform direct time-domain analysis of the high time-resolution full flux loop signals VLD2 and VLD3. We analyze plasmas where a steady H-mode is sustained over several seconds, during which all the observed ELMs are intrinsic; there is no deliberate intent to pace the ELMing process by external means. ELM occurrence times are determined from the Be II emission at the divertor. We previously found that the occurrence times of intrinsic ELMs correlate with specific phases of the VLD2 and VLD3 signals. Here, we investigate how the VLD2 and VLD3 phases vary with time in advance of the ELM occurrence time. We identify a build-up to the ELM ...
Energy Technology Data Exchange (ETDEWEB)
Takada, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kosako, Kazuaki
1999-03-01
For analyzing the decay and build-up characteristics of spallation products, the DCHAIN-SP code has been developed on the basis of the DCHAIN-2 code by revising the decay data and implementing the neutron cross section data. The decay data are newly processed from the data libraries of EAF 3.1, FENDL/D-1 and ENSDF. The neutron cross section data taken from FENDL/A-2 data library are also prepared to take account of the transmutation of nuclides by the neutron field at the produced position. The DCHAIN-SP code solves the time evolution of decay and build-up of nuclides in every decay chain by the Beteman method. The code can estimate the following physical quantities of produced nuclides: inventory, activity, decay heat by the emission of {alpha}, {beta} and {gamma}-rays, and {gamma}-ray energy spectrum, where the nuclide production rate estimated by the nucleon-meson transport code such as NMTC/JAERI97 is used as an input data. This paper describes about the function, the solution model and the database adopted in the code and explains how to use the code. (author)
Institute of Scientific and Technical Information of China (English)
曹春红; 王鹏
2014-01-01
几何约束问题的约束方程组可转化为优化模型，因此约束求解问题可以转化为优化问题。针对传统量子遗传算法个体间信息交换不足，易使算法陷入局部最优的缺点，提出了动态种群划分量子遗传算法（dynamic population divided quantum genetic algorithm，DPDQGA），并将其应用于几何约束求解中。该算法种群中的个体按照一定规则自发地进行信息交换。在每一代进化的开始阶段，分别对两个初始种群中的个体计算个体适应度。将两个种群合并，使用联赛选择的方法为种群中的个体打分，并按照得分对种群进行排序。最后将合并的种群重新划分为两个子种群。实验表明，基于动态种群划分的量子遗传算法求解几何约束问题具有更好的求解精度和求解速率。%The constraint equations of geometric constraint problem can be transformed into the optimization model, therefore constraint solving problem can be transformed into the optimization problem. Lack of information exchange between the individuals, the traditional quantum genetic algorithm is easy to fall into a local optimum. This paper proposes a dynamic population divided quantum genetic algorithm (DPDQGA) which is applied to geometric constraint solving. The individuals in populations exchange information spontaneously according to certain rules. In the beginning stage of the evolution of each generation, the individual fitness of two initial populations is calculated respectively. After merging the two populations, the league selection method is used to score the individuals in populations, and the populations are ranked according to the score. Finally, the merged populations are re-divided into two sub-populations. The experiments show that DPDQGA for solving geometric constraint problems has better accuracy and solving rate.
Institute of Scientific and Technical Information of China (English)
王继霞; 刘次华
2009-01-01
In this paper,a geometric response and normal covariace model for the missing data are assumed.We fit the model using the Monte Carlo EM(Expectation and Maximization) algorithm.The E-step is derived by Metropolis-Hastings algorithm to generate a sample for missing data,and the M-Step is done by Newton-Raphson to maximize the likelihood function.Asymptotic variances and the standard errors of the MLE of parameters are derived using the observed Fisher information.%本文研究缺失数据下对数线性模型参数的极大似然估计问题.通过Monte-Carlo EM算法去拟合所提出的模型.其中,在期望步中利用Metropolis-Hastings算法产生一个缺失数据的样本,在最大化步中利用Newton-Raphson迭代使似然函数最大化.最后,利用观测数据的Fisher信息得到参数极大似然估计的渐近方差和标准误差.
Luo, Wenhai; Hai, Faisal I; Kang, Jinguo; Price, William E; Guo, Wenshan; Ngo, Hao H; Yamamoto, Kazuo; Nghiem, Long D
2015-02-01
This study investigated the impact of salinity build-up on the performance of membrane bioreactor (MBR), specifically in terms of the removal and fate of trace organic chemicals (TrOCs), nutrient removal, and biomass characteristics. Stepwise increase of the influent salinity, simulating salinity build-up in high retention MBRs, adversely affected the metabolic activity in the bioreactor, thereby reducing organic and nutrient removal. The removal of hydrophilic TrOCs by MBR decreased due to salinity build-up. By contrast, with the exception of 17α-ethynylestradiol, the removal of all hydrophobic TrOCs was not affected at high salinity. Moreover, salinity build-up had negligible impact on the residual accumulation of TrOCs in the sludge phase except for a few hydrophilic compounds. Additionally, the response of the biomass to salinity stress also dramatically enhanced the release of both soluble microbial products (SMP) and extracellular polymeric substances (EPS), leading to severe membrane fouling.
Jenny Elvira Ciprián Sastre
2012-01-01
Research as pedagogical strategy, epistemological and methodological stance represents a new trend to build up citizenship founded on knowledge democratization. It is figured out as children and young people’s research practice which has been reclaimed by adults so far. Accordingly, it is evident that this sort of groups accompanied by adults during the inquiry stage tend to build up citizenship elements and settings based on participation, prominence, autonomy and the development of abilitie...
Resonant laser power build-up in ALPS-A 'light shining through a wall' experiment
Energy Technology Data Exchange (ETDEWEB)
Ehret, Klaus [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Frede, Maik [Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover (Germany); Ghazaryan, Samvel [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Hildebrandt, Matthias [Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover (Germany); Knabbe, Ernst-Axel [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Kracht, Dietmar [Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover (Germany); Lindner, Axel, E-mail: axel.lindner@desy.d [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany); List, Jenny [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Meier, Tobias [Max-Planck-Institute for Gravitational Physics, Albert-Einstein-Institute, and Institut fuer Gravitationsphysik, Leibniz Universitaet, Hannover, Callinstrasse 38, D-30167 Hannover (Germany); Meyer, Niels; Notz, Dieter; Redondo, Javier; Ringwald, Andreas [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Wiedemann, Guenter [Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg (Germany); Willke, Benno [Max-Planck-Institute for Gravitational Physics, Albert-Einstein-Institute, and Institut fuer Gravitationsphysik, Leibniz Universitaet, Hannover, Callinstrasse 38, D-30167 Hannover (Germany)
2009-12-21
The ALPS Collaboration runs a 'light shining through a wall' (LSW) experiment to search for photon oscillations into 'weakly interacting sub-eV particles' (WISPs) inside of a superconducting HERA dipole magnet at the site of DESY. In this paper we report on the first successful integration of a large-scale optical resonant cavity to boost the available power for WISP production in this type of experiments. The key elements are a frequency tunable narrow line-width continuous wave laser acting as the primary light source and an electronic feed-back control loop to stabilize the power build-up. We describe and characterize our apparatus and demonstrate the data analysis procedures on the basis of a brief exemplary run.
Resonant laser power build-up in ALPS. A 'light-shining-through-walls' experiment
Energy Technology Data Exchange (ETDEWEB)
Ehret, Klaus; Ghazaryan, Samvel [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Frede, Maik [Laser Zentrum Hannover e.V. (DE)] (and others)
2009-05-15
The ALPS collaboration runs a light-shining-through-walls (LSW) experiment to search for photon oscillations into weakly interacting sub-eV particles (WISPs) inside of a superconducting HERA dipole magnet at the site of DESY. In this paper we report on the first successful integration of a large-scale optical cavity to boost the available power for WISP production in this type of experiments. The key elements are a frequency tunable narrow line-width continuous wave laser acting as the primary light source and an electronic feed-back control loop to stabilize the power build-up. We describe and characterize our apparatus and demonstrate the data analysis procedures on the basis of a brief exemplary run. (orig.)
Souguir, H; Ronsin, O; Caroli, C; Baumberger, T
2015-04-01
We probe the mechanisms at work in the build-up of thermoreversible gel networks, with the help of hybrid gelatin gels containing a controlled density of irreversible, covalent crosslinks (CLs), which we quench below the physical gelation temperature. The detailed analysis of the dependence on covalent crosslink density of both the shear modulus and optical activity evolutions with time after quench enables us to identify two stages of the physical gelation process, separated by a temperature-dependent crossover modulus: (i) an early nucleation regime during which rearrangements of the triple-helix CLs play a negligible role, and (ii) a late, logarithmic aging one, which is preserved, though slowed down, in the presence of irreversible CLs. We show that aging is fully controlled by rearrangements and discuss the implication of our results in terms of the switch from an early, local dynamics to a late, cooperative long-range one.
Institute of Scientific and Technical Information of China (English)
PaulW.T.Poon; Ph.D.,F.L.A
1994-01-01
This paper starts with a brief description of what a database is followed by a short history of the development of the database system and its use; it also notes the proliferation of various kinds of databases in the 1990s. It then goes on to outline the background of establishing a Pearl River Delta Collection at the City University of Hong Kong and the Hong Kong Lingnan College. One of the tasks in this project is to build up a database of Pearl River Delta-related materials available in all the UPGC(University and Polytechnic Grant Committee)libraries in Hong Kong. The database design and structure are described, and the problems associated with data collection, source data, and updating together with their solutions are explained.
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
During the course of calculating the rice evapotranspiration using weather factors,we often find that some independent variables have multiple correlation.The phenomena can lead to the traditional multivariate regression model which based on least square method distortion.And the stability of the model will be lost.The model will be built based on partial least-square regression in the paper,through applying the idea of main component analyze and typical correlation analyze,the writer picks up some component from original material.Thus,the writer builds up the model of rice evapotranspiration to solve the multiple correlation among the independent variables (some weather factors).At last,the writer analyses the model in some parts,and gains the satisfied result.
The Build-Up Of Mass And Angular Momentum In Galaxies Across Morphology And Environment With Sami
van de Sande, Jesse; SAMI Team
2017-06-01
Studying the build-up of mass and angular momentum in galaxies is fundamental to understanding the large variations in morphology and star formation that we see in present-day galaxies. Recent cosmological hydrodynamical simulations suggest that with integral field spectroscopy (IFS) it is possible to connect the observable stellar line of sight velocity distribution in galaxies to their cosmological assembly history. In this talk I will highlight several key results from the SAMI Galaxy Survey, which currently provides two-dimensional stellar population, gas and stellar kinematic measurements for over 2000 galaxies. I will show how specific angular momentum and lambdaR (spin parameter proxy) change as a function of morphology and environment. Furthermore, I will present the higher-order kinematic classes that we find within the SAMI galaxy survey, and how they can be linked to a galaxy's assembly history. Finally, I will link the intrinsic shape of galaxies and their stellar populations to their rotational properties.
Johnson, Perry L.; Hamilton, Stephen S.; Burns, Randal; Meneveau, Charles
2017-01-01
An intrinsic property of turbulent flows is the exponential deformation of fluid elements along Lagrangian paths. The production of enstrophy by vorticity stretching follows from a similar mechanism in the Lagrangian view, though the alignment statistics differ and viscosity prevents unbounded growth. In this paper, the stretching properties of fluid elements and vorticity along Lagrangian paths are studied in a channel flow at Reτ=1000 and compared with prior known results from isotropic turbulence. To track Lagrangian paths in a public database containing direct numerical simulation results, the task-parallel algorithm previously employed in the isotropic database is extended to the case of flow in a bounded domain. It is shown that above 100 viscous units from the wall, stretching statistics are equal to their isotropic values, in support of the local isotropy hypothesis. In the viscous sublayer, these stretching statistics approach values more consistent with an unsteady two-dimensional shear flow, in which exponential stretching no longer occurs. Normalized by dissipation rate, the stretching in the buffer layer and below is less efficient due to less favorable alignment statistics. The Cramér function characterizing cumulative Lagrangian stretching statistics shows that overall the channel flow has about half of the stretching per unit dissipation compared with isotropic turbulence.
Valero-Cabré, Antoni; Pascual-Leone, Alvaro; Rushmore, Richard J
2008-02-01
A single session of repetitive transcranial magnetic stimulation (rTMS) can induce behavioural effects that outlast the duration of the stimulation train itself (off-line effects). Series of rTMS sessions on consecutive days are being used for therapeutic applications in a variety of disorders and are assumed to lead to the build-up of cumulative effects. However, no studies have carefully assessed this notion. In the present study we applied 30 daily sessions of 1 Hz rTMS (continuous train of 20 min) to repeatedly modulate activity in the posterior parietal cortex and associated neural systems in two intact cats. We assessed the effect on visuospatial orientation before and after each stimulation session. Cumulative sessions of rTMS progressively induced visuospatial neglect-like 'after-effects' of greater magnitude (from 5-10% to 40-50% error levels) and increasing spatial extent (from 90-75 degrees to 45-30 degrees eccentricity locations), affecting the visual hemifield contralateral to the stimulated hemisphere. Nonetheless, 60 min after each TMS session, visual detection-localization abilities repeatedly returned to baseline levels. Furthermore, no lasting behavioural effect could be demonstrated at any time across the study, when subjects were tested 1 or 24 h post-rTMS. We conclude that the past history of periodically cumulative rTMS sessions builds up a lasting 'memory', resulting in increased facilitation to subsequent TMS-induced disruptions. Such a phenomenon allows a behavioural effect of progressively higher magnitude, but equal duration, in response to individual TMS interventions.
Almaroof, A; Rojo, L; Mannocci, F; Deb, S
2016-02-01
To formulate and evaluate new dual cured resin composite based on the inclusion of eugenyl methacrylate monomer (EgMA) with Bis-GMA/TEGDMA resin systems for intracanal post cementation and core build-up restoration of endodontically treated teeth. EgMA was synthesized and incorporated at 5% (BTEg5) or 10% (BTEg10) into dual-cure formulations. Curing properties, viscosity, Tg, radiopacity, static and dynamic mechanical properties of the composites were determined and compared with Clearfil™DC Core-Plus, a commercial dual-cure, two-component composite. Statistical analysis of the data was performed with ANOVA and the Tukey's post-hoc test. The experimental composites were successfully prepared, which exhibited excellent curing depths of 4.9, 4.7 and 4.2 mm for BTEg0, BTEg5 and BTEg10 respectively, which were significantly higher than Clearfil™DC. However, the inclusion of EgMA initially led to a lower degree of cure, which increased when measured at 24 h with values comparable to formulations without EgMA, indicating post-curing. The inclusion of EgMA also lowered the polymerization exotherm thereby reducing the potential of thermal damage to host tissue. Both thermal and viscoelastic analyses confirmed the ability of the monomer to reduce the stiffness of the composites by forming a branched network. The compressive strength of BTEg5 was significantly higher than the control whilst flexural strength increased significantly from 95.9 to 114.8 MPa (BTEg5) and 121.9 MPa (BTEg10). Radiopacity of the composites was equivalent to ∼3 mm Al allowing efficient diagnosis. The incorporation of EgMA within polymerizable formulations provides a novel approach to prepare reinforced resin composite material for intracanal post cementation and core build-up and the potential to impart antibacterial properties of eugenol to endodontic restorations. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Institute of Scientific and Technical Information of China (English)
张政武
2012-01-01
从实际计算的角度出发,研究了两平面二次曲线射影不变量,并对其进行了相应的几何解释,提出了相应的计算方法。首先从两二次型的不变量推导出两平面二次曲线的射影不变量,接着利用两平面二次曲线的共自极三角形给出了两平面二次曲线不变量的几何解释及计算方法。在此基础上,通过举例分析和实验验证,证明文中所给公式的正确性。%The object recognition based on the invariants is the most active research area in the computer vision. The conventional studies about invariants are that these invariants are derived for planar objects using points and lines from images. Nowadays, more and more interest comes from 3 D reconstruction based on the invariants of conics. The projective invariants of a pair of coplanar conics are studied from the perspective of computational proces- ses and the geometrically interpreted is proposed in this paper. The projective invariants of a pair of eoplanar conics are first defined from invariants of a pair of quadratic forms. Then the invariants are geometrically interpreted by using the common self-polar triangle of the two conics, and the algorithm is proposed in this paper. The result of example shows that this formula in this paper is correct on the basis of present studies.
A Color Image Watermarking Scheme Resistant against Geometrical Attacks
Directory of Open Access Journals (Sweden)
Y. Xing
2010-04-01
Full Text Available The geometrical attacks are still a problem for many digital watermarking algorithms at present. In this paper, we propose a watermarking algorithm for color images resistant to geometrical distortions (rotation and scaling. The singular value decomposition is used for watermark embedding and extraction. The log-polar map- ping (LPM and phase correlation method are used to register the position of geometrical distortion suffered by the watermarked image. Experiments with different kinds of color images and watermarks demonstrate that the watermarking algorithm is robust to common image processing attacks, especially geometrical attacks.
Study on the Grey Polynomial Geometric Programming
Institute of Scientific and Technical Information of China (English)
LUODang
2005-01-01
In the model of geometric programming, values of parameters cannot be gotten owing to data fluctuation and incompletion. But reasonable bounds of these parameters can be attained. This is to say, parameters of this model can be regarded as interval grey numbers. When the model contains grey numbers, it is hard for common programming method to solve them. By combining the common programming model with the grey system theory,and using some analysis strategies, a model of grey polynomial geometric programming, a model of 8 positioned geometric programming and their quasi-optimum solution or optimum solution are put forward. At the same time, we also developed an algorithm for the problem.This approach brings a new way for the application research of geometric programming. An example at the end of this paper shows the rationality and feasibility of the algorithm.
Image coding with geometric wavelets.
Alani, Dror; Averbuch, Amir; Dekel, Shai
2007-01-01
This paper describes a new and efficient method for low bit-rate image coding which is based on recent development in the theory of multivariate nonlinear piecewise polynomial approximation. It combines a binary space partition scheme with geometric wavelet (GW) tree approximation so as to efficiently capture curve singularities and provide a sparse representation of the image. The GW method successfully competes with state-of-the-art wavelet methods such as the EZW, SPIHT, and EBCOT algorithms. We report a gain of about 0.4 dB over the SPIHT and EBCOT algorithms at the bit-rate 0.0625 bits-per-pixels (bpp). It also outperforms other recent methods that are based on "sparse geometric representation." For example, we report a gain of 0.27 dB over the Bandelets algorithm at 0.1 bpp. Although the algorithm is computationally intensive, its time complexity can be significantely reduced by collecting a "global" GW n-term approximation to the image from a collection of GW trees, each constructed separately over tiles of the image.
Zhang, Mao-Yu; Li, Jian; Hu, Hao; Wang, Yi-Tao
2015-11-04
Monoclonal antibodies (mAbs), as an emerging technology, have become increasingly important in the development of human therapeutic agents. How developing countries such as China could seize this emerging technological opportunity remains a poorly studied issue in prior literature. Thus, this paper aims to investigate the research and development of mAbs in China based on an innovation system functions approach and probes into the question of how China has been taking advantage of emerging technologies to overcome its challenges of building up a complete innovation system in developing mAbs. Mixed research methods were applied by combining archival data and field interviews. Archival data from the China Food and Drug Administration, Web of Science, the United States Patent and Trademark Office, the Chinese Clinical Trial Registry, and the National Science and Technology Report Service were used to examine the status quo of the technology and research and development (R&D) activities in China, while the opinions of researchers and managers in this field were synthesized from the interviews. From the perspective of innovation system functions, technological development of mAb in China is being driven by incentives such as the subsidies from the State and corporate R&D funding. Knowledge diffusion has been well served over the last 10 years through exchanging information on networks and technology transfer with developed countries. The State has provided clear guidance on search of emerging mAb technologies. Legitimacy of mAb in China has gained momentum owing to the implementation of government policies stipulated in the "The Eleventh Five-year Plan" in 2007, as well as national projects such as the "973 Program" and "863 Program", among others. The potential of market formation stays high because of the rising local demand and government support. Entrepreneurial activities for mAb continue to prosper. In addition, the situation of resource supply has been improved
Directory of Open Access Journals (Sweden)
Nunzia Sanarico
2015-12-01
Full Text Available INTRODUCTION: Prevalence of infection with HIV-1 non-B subtypes in Italy has been reported to raise, due to increased migration flows and travels. HIV-1 variants show different biological and immunological properties that impact on disease progression rate, response to antiretroviral therapy (ART and sensitivity of diagnostic tests with important implications for public health. Therefore, a constant surveillance of the dynamics of HIV variants in Italy should be a high public health priority. Organization of surveillance studies requires building up a platform constituted of a network of clinical centers, laboratories and institutional agencies, able to properly collect samples for the investigation of HIV subtypes heterogeneity and to provide a database with reliable demographic, clinical, immunological and virological data. AIM: We here report our experience in building up such a platform, co-ordinated by the National AIDS Center of the Istituto Superiore di Sanita, taking advantage of a pilot study aimed at evaluating HIV subtypes diversity in populations of HIV-infected migrant people in Italy. MATERIALS AND METHODS: Four hundred and thirty four HIV-infected migrants were enrolled in 9 Italian clinical centers located throughout the Italian territory. Standard Operating Procedures (SOPs for sample collection were provided by the National AIDS Center to each clinical center. In addition, clinical centers were required to fill up a case report form (crf for each patient, which included demographic, clinical, immunological and virological information. RESULTS: All centers properly collected and stored samples from each enrolled individual. Overall, the required information was correctly provided for more than 90% of the patients. However, some fields of the crf, particularly those including information on the last HIV-negative antibody test and presence of co-infections, were properly filled up in less than 80% of the enrolled migrants. Centers
Federal Laboratory Consortium — Purpose: The mission of the Geometric Design Laboratory (GDL) is to support the Office of Safety Research and Development in research related to the geometric design...
On Geometric Infinite Divisibility
Sandhya, E.; Pillai, R. N.
2014-01-01
The notion of geometric version of an infinitely divisible law is introduced. Concepts parallel to attraction and partial attraction are developed and studied in the setup of geometric summing of random variables.
Geometric Modelling by Recursively Cutting Vertices
Institute of Scientific and Technical Information of China (English)
吕伟; 梁友栋; 等
1989-01-01
In this paper,a new method for curve and surface modelling is introduced which generates curves and surfaces by recursively cutting and grinding polygons and polyhedra.It is a generalization of the existing corner-cutting methods.A lot of properties,such as geometric continuity,representation,shape-preserving,and the algorithm are studied which show that such curves and surfaces are suitable for geometric designs in CAD,computer graphics and their application fields.
Directory of Open Access Journals (Sweden)
Nugroho Adi
2017-07-01
Full Text Available In the field of energy transport, High-Voltage DC (HVDC technologies are booming at present due to the more flexible power converter solutions along with needs to bring electrical energy from distributed production areas to consumption sites and to strengthen large-scale energy networks. These developments go with challenges in qualifying insulating materials embedded in those systems and in the design of insulations relying on stress distribution. Our purpose in this communication is to illustrate how far the field distribution in DC insulation systems can be anticipated based on conductivity data gathered as a function of temperature and electric field. Transient currents and conductivity estimates as a function of temperature and field were recorded on miniaturized HVDC power cables with construction of 1.5 mm thick crosslinked polyethylene (XLPE insulation. Outputs of the conductivity model are compared to measured field distributions using space charge measurements techniques. It is shown that some features of the field distribution on model cables put under thermal gradient can be anticipated based on conductivity data. However, space charge build-up can induce substantial electric field strengthening when materials are not well controlled.
Effect of the thermoplastic masks on dose distribution in the build-up region for photon beams
Półtorak, Michał; Fujak, Edyta; Kukołowicz, Paweł
2016-03-01
The aim of the study was to investigate the influence of thermoplastic masks material (Klarity Medical&Equipment Co., Guangzhou, China) with different diameters of holes (ϕ 0.25 cm and ϕ 0.40 cm) on the dose distribution in the build-up region for photon beams. Measurements were made for external radiation beams produced by the linear accelerator (TrueBeam, Varian Medical Systems, Inc., Palo Alto, CA, USA) using the Markus parallel plane ionization chamber and the Unidos electrometer (both from PTW, Freiburg, Germany). Measurements were made in a solid water phantom for two photon energies 6 MV and 15 MV, at 90 cm source to skin distance, for four fields of 5 cm × 5 cm, 10 cm × 10 cm, 15 cm × 15 cm and 20 cm × 20 cm. Compared to the open field, the maximum dose with mask was closer to the surface of the phantom by about 1.4 mm and 1.2 mm for 6 MV and 15 MV X-Rays, respectively. The surface dose increase from 10% to 42% for 6 MV and from 5% to 28% for 15 MV X-Rays.
Directory of Open Access Journals (Sweden)
F. Xystrakis
2013-03-01
Full Text Available Historical fire records and meteorological observations spanning over one century (1894–2010, were assembled in a database to collect long-term fire and weather data in Greece. Positive/negative events of fire occurrence on an annual basis were considered the years where the annual values of the examined parameters were above (positive values or below (negative values the 95% confidence limits around the trend line of the corresponding parameter. To analyze the association of positive/negative events of fire occurrence and meteorological extremes, we proceeded with a cross-tabulation analysis based on a Monte Carlo randomization. Positive/negative values of total annual precipitation were randomly associated with the corresponding values of burned areas, and significant associations were observed for seasonal precipitation totals (spring and fire season. Fire season precipitation is the dominant factor coinciding with negative values of area burned, while years with high spring precipitation coincide with large burnt area burned. These results demonstrate the dual role of precipitation in controlling a fire's extent through fuel build-up and dryness. Additionally, there is a clear outperformance of precipitation-related against temperature-related weather variables revealing that, at least in Greece, fire spread is controlled by precipitation totals rather than air temperature.
A Geometrical Method of Decoupling
Baumgarten, Christian
2012-01-01
In a preceeding paper the real Dirac matrices have been introduced to coupled linear optics and a recipe to decouple positive definite Hamiltonians has been given. In this article a geometrical method is presented which allows to decouple regular {\\it and} irregular systems with the same straightforward method and to compute the eigenvalues and eigenvectors of Hamiltonian matrices with both, real and imaginary eigenvalues. It is shown that the algebraic decoupling is closely related to a geometric "decoupling" by the orthogonalization of the vectors $\\vec E$, $\\vec B$ and $\\vec p$, that were introduced with the so-called "electromechanical equivalence" (EMEQ). When used iteratively, the decoupling algorithm can also be applied to n-dimensional non-dissipative systems.
Directory of Open Access Journals (Sweden)
Jenny Elvira Ciprián Sastre
2012-06-01
Full Text Available Research as pedagogical strategy, epistemological and methodological stance represents a new trend to build up citizenship founded on knowledge democratization. It is figured out as children and young people’s research practice which has been reclaimed by adults so far. Accordingly, it is evident that this sort of groups accompanied by adults during the inquiry stage tend to build up citizenship elements and settings based on participation, prominence, autonomy and the development of abilities and skills, knowledge democratization ,science demythologizing, and the break of the patronizing paradigm that has had an effect on humanity during history.
Model-based vision using geometric hashing
Akerman, Alexander, III; Patton, Ronald
1991-04-01
The Geometric Hashing technique developed by the NYU Courant Institute has been applied to various automatic target recognition applications. In particular, I-MATH has extended the hashing algorithm to perform automatic target recognition ofsynthetic aperture radar (SAR) imagery. For this application, the hashing is performed upon the geometric locations of dominant scatterers. In addition to being a robust model-based matching algorithm -- invariant under translation, scale, and 3D rotations of the target -- hashing is of particular utility because it can still perform effective matching when the target is partially obscured. Moreover, hashing is very amenable to a SIMD parallel processing architecture, and thus potentially realtime implementable.
Geometric algorithms for delineating geographic regions
Reinbacher, I.
2006-01-01
Everyone of us is used to geographical regions like the south of Utrecht, the dutch Randstad, or the mountainous areas of Austria. Some of these regions have crisp, fixed boundaries like Utrecht or Austria. Others, like the dutch Randstad and the Austrian mountains, have no such boundaries and are u
Geometric algorithms for delineating geographic regions
Reinbacher, I.
2006-01-01
Everyone of us is used to geographical regions like the south of Utrecht, the dutch Randstad, or the mountainous areas of Austria. Some of these regions have crisp, fixed boundaries like Utrecht or Austria. Others, like the dutch Randstad and the Austrian mountains, have no such boundaries and are
Geometric hashing and object recognition
Stiller, Peter F.; Huber, Birkett
1999-09-01
We discuss a new geometric hashing method for searching large databases of 2D images (or 3D objects) to match a query built from geometric information presented by a single 3D object (or single 2D image). The goal is to rapidly determine a small subset of the images that potentially contain a view of the given object (or a small set of objects that potentially match the item in the image). Since this must be accomplished independent of the pose of the object, the objects and images, which are characterized by configurations of geometric features such as points, lines and/or conics, must be treated using a viewpoint invariant formulation. We are therefore forced to characterize these configurations in terms of their 3D and 2D geometric invariants. The crucial relationship between the 3D geometry and its 'residual' in 2D is expressible as a correspondence (in the sense of algebraic geometry). Computing a set of generating equations for the ideal of this correspondence gives a complete characterization of the view of independent relationships between an object and all of its possible images. Once a set of generators is in hand, it can be used to devise efficient recognition algorithms and to give an efficient geometric hashing scheme. This requires exploiting the form and symmetry of the equations. The result is a multidimensional access scheme whose efficiency we examine. Several potential directions for improving this scheme are also discussed. Finally, in a brief appendix, we discuss an alternative approach to invariants for generalized perspective that replaces the standard invariants by a subvariety of a Grassmannian. The advantage of this is that one can circumvent many annoying general position assumptions and arrive at invariant equations (in the Plucker coordinates) that are more numerically robust in applications.
SU-E-T-492: Influence of Clipping PTV in Build-Up Region On IMRT Plan Quality and Deliverability
Energy Technology Data Exchange (ETDEWEB)
Sharma, S; Manigandan, D; Sahai, P; Biswas, A; Subramani, V; Chander, S; Julkha, P; Rath, G [Fortis Hospital, Mohali, Punjab (India)
2015-06-15
Purpose: To study the influence of clipping PTV from body contour on plan quality and deliverability in build-up region for superficial target. Methods: Five previously treated patients of post-operative carcinoma of parotid were re-planned for IMRT (6MV X-rays, sliding window technique, five fields and 60Gy/30 fractions) using eclipse treatment planning system (TPS) by keeping dose volume constraints and all other parameters constant, only PTV was clipped from body contour by 0mm, 1mm, 2mm and 3mm respectively. Planned fluence was transferred to previously scanned solid water phantom by placing I’matriXX array at 0.5cm depth (2mm slab+3mm inherent). Fluence was delivered by Varian CL2300C/D linac at 99.5cm source to detector distance. Measured fluence was compared with TPS dose plane using 2D gamma evaluation using 3%/3mm DTA criteria. Total MU (monitor unit) required to deliver a plan was also noted. For plan quality, PTV, maximum-dose, minimum-dose, coverage index (CI=PTV volume covered by prescription dose/PTV) and heterogeneity index HI=D5/D95 were analyzed using dose volume histogram (DVH). Results: The Result of gamma function analysis for I’matriXX and TPS were 97.63±1.79%, 97.48±0.99, 98.08±0.89% and 98.01±0.78% at 0.5cm build-up depth for 0, 1, 2 and 3mm PTV clipping, respectively. I’matriXX measured dose was higher compared to TPS. Total MU required for delivering a plan were 552±61, 503±47, 436±24 and 407±22. Maximum-dose to PTV was 6635.80±62.01cGy, 6635.80±40.60cGy, 6608.43±51.07cGy and 6564.20±28.51cGy. Similarly, minimum-dose to PTV was 3306.23±458.56cGy, 3546.57±721.01cGy, 4591.43±298.81cGy and 4861.90±412.40cGy. CI was 0.9347±0.020, 0.9398±0.021, 0.9448±0.022 and 0.9481±0.021. Similarly, HI was 1.089±0.015, 1.084±0.014, 1.078±0.009 and 1.074±0.008 for 0, 1, 2 and 3mm PTV clipping, respectively. Conclusion: Gamma function analysis resulted in almost similar results. However, I’matriXX was overestimating the dose
Artifacts in time-resolved NUS: A case study of NOE build-up curves from 2D NOESY
Dass, Rupashree; Kasprzak, Paweł; Koźmiński, Wiktor; Kazimierczuk, Krzysztof
2016-04-01
Multidimensional NMR spectroscopy requires time-consuming sampling of indirect dimensions and so is usually used to study stable samples. However, dynamically changing compounds or their mixtures commonly occur in problems of natural science. Monitoring them requires the use multidimensional NMR in a time-resolved manner - in other words, a series of quick spectra must be acquired at different points in time. Among the many solutions that have been proposed to achieve this goal, time-resolved non-uniform sampling (TR-NUS) is one of the simplest. In a TR-NUS experiment, the signal is sampled using a shuffled random schedule and then divided into overlapping subsets. These subsets are then processed using one of the NUS reconstruction methods, for example compressed sensing (CS). The resulting stack of spectra forms a temporal "pseudo-dimension" that shows the changes caused by the process occurring in the sample. CS enables the use of small subsets of data, which minimizes the averaging of the effects studied. Yet, even within these limited timeframes, the sample undergoes certain changes. In this paper we discuss the effect of varying signal amplitude in a TR-NUS experiment. Our theoretical calculations show that the variations within the subsets lead to t1 -noise, which is dependent on the rate of change of the signal amplitude. We verify these predictions experimentally. As a model case we choose a novel 2D TR-NOESY experiment in which mixing time is varied in parallel with shuffled NUS in the indirect dimension. The experiment, performed on a sample of strychnine, provides a near-continuous NOE build-up curve, whose shape closely reflects the t1 -noise level. 2D TR-NOESY reduces the measurement time compared to the conventional approach and makes it possible to verify the theoretical predictions about signal variations during TR-NUS.
Institute of Scientific and Technical Information of China (English)
张义德; 关威
2011-01-01
在二维情况下,如果地质结构的分界面为一条有固定斜率的斜线,则反演该界面时所需要确定的参数可以归结为两个:一个是界面上的反射点,另一个是界面的斜率.依据Snell定理,利用源点与反射波最短路径点之间的几何关系,导出一种快速反演斜界面的方法.作为算例,首先利用时域有限差分法对一个二维倾斜界面模型进行了数值模拟,而后利用该方法进行反演,界面位置误差在1％以内.%In two-dimensional space, if an interface of geologic structure has one fixed slope, then only two parameters needs to determined for the inversion of the interface. One is a reflect point in it, and another is the slope. Using the geometrical relationship between the source point and the fastest travel point of the reflect wave, a quick inversion algorithm was gained based on Snell theorem. At last, some examples of numerical simulation were given and it is very good. The inversion data was got from a two-dimensional model with a slope interface using FDTD.
A Geometric Study of V-style Pop-ups: Theories and Algorithms%V型立体纸雕的几何理论与算法的研究
Institute of Scientific and Technical Information of China (English)
李先颖; 顾研; 胡事民
2012-01-01
立体书是一种独特的纸张艺术形式,有着精细的几何结构.针对一类特殊的V型立体纸雕进行了系统性的研究,给出了V型立体纸雕可实现性的充分条件,使其可以只借助2张支撑面的力量进行打开和关闭,同时在这个过程中所有的面片都保持刚性并且相互不产生自交.基于这些充分条件,文中分别实现了一个计算机辅助交互V型纸雕设计工具,以及一个基于体方法的自动生成算法.%Pop-up books are a fascinating form of paper art with intriguing geometric properties. In this paper, we present a systematic study of a simple but common class of pop-ups consisting of patches falling into four parallel groups, which we call v-style pop-ups. We give sufficient conditions for a v-style paper structure to be pop-uppable. That is, it can be closed flat while maintaining the rigidity of the patches, the closing and opening do not need extra force besides holding two patches and are free of intersections, and the closed paper is contained within the page border. These conditions allow us to identify novel mechanisms for making pop-ups. Based on the theory and mechanisms, we developed an interactive tool for designing v-style pop-ups and an automated construction algorithm from a given geometry, both of which guaranteeing the pop-uppability of the results.
Geometrization of Trace Formulas
Frenkel, Edward
2010-01-01
Following our joint work arXiv:1003.4578 with Robert Langlands, we make the first steps toward developing geometric methods for analyzing trace formulas in the case of the function field of a curve defined over a finite field. We also suggest a conjectural framework of geometric trace formulas for curves defined over the complex field, which exploits the categorical version of the geometric Langlands correspondence.
Localized Geometric Query Problems
Augustine, John; Maheshwari, Anil; Nandy, Subhas C; Roy, Sasanka; Sarvattomananda, Swami
2011-01-01
A new class of geometric query problems are studied in this paper. We are required to preprocess a set of geometric objects $P$ in the plane, so that for any arbitrary query point $q$, the largest circle that contains $q$ but does not contain any member of $P$, can be reported efficiently. The geometric sets that we consider are point sets and boundaries of simple polygons.
Xystrakis, F.; Kallimanis, A. S.; Dimopoulos, P.; Halley, J. M.; Koutsias, N.
2014-01-01
Historical fire records and meteorological observations spanning over one century (1894-2010) were assembled in a database to collect long-term fire and weather data in Greece. Positive/negative events of fire occurrence on an annual basis were considered as the years where the annual values of the examined parameters were above (positive values) or below (negative values) the 95% confidence limits around the trend line of the corresponding parameter. To analyse the association of positive/negative events of fire occurrence with meteorological extremes, we proceeded with a cross-tabulation analysis based on a Monte Carlo randomization. Positive/negative values of total annual precipitation were randomly associated with the corresponding values of burned areas, and significant associations were observed for seasonal precipitation totals (spring and fire season). Fire season precipitation is the dominant factor coinciding with negative values of area burned, while years with high spring precipitation coincide with years with large areas burned. These results demonstrate the dual role of precipitation in controlling a fire's extent through fuel build-up and dryness. Additionally, there is a clear outperformance of precipitation-related variables compared with temperature-related weather revealing that, at least in Greece, total area burned at the national scale is controlled by precipitation totals rather than air temperature. This analysis improves our understanding of the underlying mechanisms of fire regimes and provides valuable information concerning the development of models relating fire activity to weather parameters, which are essential when facing a changing climate that may be associated with shifts in various aspects of the typical fire regimes of ecosystems. Our results may allow fire managers to more easily incorporate the effect of extreme weather conditions into long-term planning strategies. They contribute to the exploration of fire
A comprehensive interpretation of the NEEM basal ice build-up using a multi-parametric approach
Goossens, Thomas; Sapart, Célia J.; Dahl-Jensen, Dorthe; Popp, Trevor; El Amri, Saïda; Tison, Jean-Louis
2016-03-01
stratified debris-rich layers and the ice containing dispersed debris layers respectively express an "open" or "closed" system melting/refreezing signature, somewhat blurred by mixing processes in the upper part of the sequence. Climatic reconstruction is therefore prohibited from these ice types. We propose a first interpretative framework for the build-up of the NEEM basal ice sequence, based on the origin of the various ice types.
Geometrical method of decoupling
Baumgarten, C.
2012-12-01
The computation of tunes and matched beam distributions are essential steps in the analysis of circular accelerators. If certain symmetries—like midplane symmetry—are present, then it is possible to treat the betatron motion in the horizontal, the vertical plane, and (under certain circumstances) the longitudinal motion separately using the well-known Courant-Snyder theory, or to apply transformations that have been described previously as, for instance, the method of Teng and Edwards. In a preceding paper, it has been shown that this method requires a modification for the treatment of isochronous cyclotrons with non-negligible space charge forces. Unfortunately, the modification was numerically not as stable as desired and it was still unclear, if the extension would work for all conceivable cases. Hence, a systematic derivation of a more general treatment seemed advisable. In a second paper, the author suggested the use of real Dirac matrices as basic tools for coupled linear optics and gave a straightforward recipe to decouple positive definite Hamiltonians with imaginary eigenvalues. In this article this method is generalized and simplified in order to formulate a straightforward method to decouple Hamiltonian matrices with eigenvalues on the real and the imaginary axis. The decoupling of symplectic matrices which are exponentials of such Hamiltonian matrices can be deduced from this in a few steps. It is shown that this algebraic decoupling is closely related to a geometric “decoupling” by the orthogonalization of the vectors E→, B→, and P→, which were introduced with the so-called “electromechanical equivalence.” A mathematical analysis of the problem can be traced down to the task of finding a structure-preserving block diagonalization of symplectic or Hamiltonian matrices. Structure preservation means in this context that the (sequence of) transformations must be symplectic and hence canonical. When used iteratively, the decoupling
Energy Technology Data Exchange (ETDEWEB)
Nguyen, T B; Hoole, A C F; Thomas, S J [Medical Physics Department, Addenbrooke' s Hospital, Hills Road, Cambridge CB2 0QQ (United Kingdom); Burnet, N G [Department of Oncology, University of Cambridge, Oncology Centre (Box 193), Addenbrooke' s Hospital, Hills Road, Cambridge, CB2 0QQ (United Kingdom)], E-mail: binh.nguyen-thai@polytechnique.org
2009-04-21
A common clinical problem in IMRT, especially when treating head and neck cases, is that the clinical target volume (CTV) stops short of the skin surface, whilst the margin for geometric uncertainties may take the planning target volume (PTV) to the skin surface or beyond. In these cases, optimization leads to over-dosing of the skin, unless the planner resorts to procedural tricks to avoid this, such as the use of pretend bolus or reduction of the PTV followed by adding 'flash' after optimization. This paper describes a method of avoiding the need for these tricks by using a multiple-isocentre CTV-based objective function. This enables plans to be produced that will give good coverage of the CTV for all the geometrical uncertainties that would have been covered by the PTV without causing the problem of over-dosing the skin. Eight isocentre shifts, equally distributed on the surface of a sphere with a radius equal to the CTV-PTV margin, are shown to be adequate for the optimization process. The resulting fluence maps are much simpler than those resulting from PTV optimization and will therefore be simpler to deliver. The method also permits better sparing of organs at risk such as the spinal cord.
Nguyen, T. B.; Hoole, A. C. F.; Burnet, N. G.; Thomas, S. J.
2009-04-01
A common clinical problem in IMRT, especially when treating head and neck cases, is that the clinical target volume (CTV) stops short of the skin surface, whilst the margin for geometric uncertainties may take the planning target volume (PTV) to the skin surface or beyond. In these cases, optimization leads to over-dosing of the skin, unless the planner resorts to procedural tricks to avoid this, such as the use of pretend bolus or reduction of the PTV followed by adding 'flash' after optimization. This paper describes a method of avoiding the need for these tricks by using a multiple-isocentre CTV-based objective function. This enables plans to be produced that will give good coverage of the CTV for all the geometrical uncertainties that would have been covered by the PTV without causing the problem of over-dosing the skin. Eight isocentre shifts, equally distributed on the surface of a sphere with a radius equal to the CTV-PTV margin, are shown to be adequate for the optimization process. The resulting fluence maps are much simpler than those resulting from PTV optimization and will therefore be simpler to deliver. The method also permits better sparing of organs at risk such as the spinal cord.
Lan, Yihua; Li, Cunhua; Ren, Haozheng; Zhang, Yong; Min, Zhifang
2012-10-01
sorting method. By integrating a smart constraint adding/deleting scheme within the iteration framework, the new technique builds up an improved algorithm for solving the fluence map optimization with dose-volume constraints.
Exploring New Geometric Worlds
Nirode, Wayne
2015-01-01
When students work with a non-Euclidean distance formula, geometric objects such as circles and segment bisectors can look very different from their Euclidean counterparts. Students and even teachers can experience the thrill of creative discovery when investigating these differences among geometric worlds. In this article, the author describes a…
Hao, Qingzhen; Wang, Luo; Oldfield, Frank; Peng, Shuzhen; Qin, Li; Song, Yang; Xu, Bing; Qiao, Yansong; Bloemendal, Jan; Guo, Zhengtang
2014-05-01
The growth and decay of the Northern Hemisphere ice volume led to alternations of glacial and interglacial climate. Unfortunately, long-term continuous records of ice-sheet variability in the Northern Hemisphere during the Quaternary period only are scarce because benthic δ18O records represent an integrated signal of changes in ice volume in both polar regions. However, variations in Northern Hemisphere ice sheets influence the Siberian High (an atmospheric pressure system), so variations in the East Asian winter monsoon (EAWM)—as recorded in the aeolian dust deposits on the Chinese Loess Plateau—can serve as a useful proxy of Arctic climate variability. Here we present an EAWM proxy record using grain-size variations in two parallel loess sections over the past 900 kyr to address the timing of build-up of Northern hemisphere ice sheets around 413 kyr mimina in eccentricity and precessional variability. These periods are regarded as the astronomical analogues of the present interglacial. The grain-size-inferred intensity of the EAWM records shows that the wind strength of EAWM increased rapidly after the end of most interglacials. However, during periods of low eccentricity and precessional variability around 400 kyr and 800 kyr ago, EAWM remains weak for up to 20 kyr after the end of the interglacial episodes MIS 11, MIS 19 and MIS 21. We conclude that the delayed increase in wind strength of the EAWM was caused by delayed buildup of Arctic ice sheets at the ends of the interglacials at 400 kyr intervals, which had led to much longer climate of interglacial mode at high northern latitudes than expected from the marine oxygen isotope records. During these times, the less severe summer insolation minima at 65° N (modulated by 413-kyr eccentricity cycles) would have suppressed ice and snow accumulation, leading to a weak Siberian High and, consequently, weak EAWM winds. Astronomically driven insolation during the present interglacial and in the near future is
Stokes, Chris R.; Tarasov, Lev; Dyke, Arthur S.
2012-09-01
The North American Ice Sheet Complex played a major role in global sea level fluctuations during the Late Quaternary but our knowledge of its dynamics is based mostly on its demise from the Last Glacial Maximum (LGM), a period characterised by non-linear behaviour in the form of punctuated ice margin recession, episodic ice streaming and major shifts in the location of ice divides. In comparison, knowledge of the pre-LGM ice complex is poorly constrained, largely because of the fragmentary nature of the evidence relating to ice sheet build-up. In this paper, we explore the inception and growth of ice (120-20 ka) using a glacial systems model which has been calibrated against a large and diverse set of data relating to the deglacial interval. We make use of calibration data prior to the LGM but its scarcity introduces greater uncertainty, which is partly alleviated by our large ensemble analysis. Results suggest that, following the last interglaciation (Oxygen Isotope Stage: OIS 5e), the ice complex initiated over the north-eastern Canadian Arctic and in the Cordillera within a few thousand years. It then underwent rapid growth to an OIS 5 maximum at ˜110 ka (5d) and covered ˜70% of the area occupied by the LGM ice cover (although only 30% by volume). An OIS 5 minimum is modelled at ˜80 ka (5a), before a second phase of rapid growth at the start of OIS 4, which culminated in a large ice complex at ˜65 ka (almost as large as at the LGM). Subsequent deglaciation was rapid (maximum modelled sea level contribution of >16 cm per century) and resulted in an OIS 3 minimum between ca 55-60 ka. Thereafter, the ice complex grew towards its LGM configuration, interrupted by several phases of successively less significant mass loss. Our results support and extend previous inferences based on geological evidence and reinforce the notion of a highly dynamic pre-LGM ice complex (e.g. with episodes of ±10 s m of eustatic sea level equivalent in ice increases towards the LGM
Geometric Computations on Indecisive and Uncertain Points
Jorgensen, Allan; Phillips, Jeff M
2012-01-01
We study computing geometric problems on uncertain points. An uncertain point is a point that does not have a fixed location, but rather is described by a probability distribution. When these probability distributions are restricted to a finite number of locations, the points are called indecisive points. In particular, we focus on geometric shape-fitting problems and on building compact distributions to describe how the solutions to these problems vary with respect to the uncertainty in the points. Our main results are: (1) a simple and efficient randomized approximation algorithm for calculating the distribution of any statistic on uncertain data sets; (2) a polynomial, deterministic and exact algorithm for computing the distribution of answers for any LP-type problem on an indecisive point set; and (3) the development of shape inclusion probability (SIP) functions which captures the ambient distribution of shapes fit to uncertain or indecisive point sets and are admissible to the two algorithmic constructi...
Geometric reconstruction methods for electron tomography
Alpers, Andreas; König, Stefan; Pennington, Robert S; Boothroyd, Chris B; Houben, Lothar; Dunin-Borkowski, Rafal E; Batenburg, Kees Joost
2012-01-01
Electron tomography is becoming an increasingly important tool in materials science for studying three-dimensional morphologies and chemical compositions of nanostructures. The image quality obtained by many current algorithms is seriously affected by the problems of missing wedge artefacts and nonlinear projection intensities due to diffraction effects. The former refers to the fact that data cannot be acquired over the full $180^\\circ$ tilt range; the latter implies that for some orientations, crystalline structures can show strong contrast changes. To overcome these problems we introduce four algorithms from the mathematical fields of geometric and discrete tomography. The algorithms incorporate geometric prior knowledge (mainly convexity and homogeneity), which also in principle considerably reduces the number of tilt angles required. Results are discussed for the reconstruction of an InAs nanowire.
Geometric and unipotent crystals
Berenstein, Arkady; Kazhdan, David
1999-01-01
In this paper we introduce geometric crystals and unipotent crystals which are algebro-geometric analogues of Kashiwara's crystal bases. Given a reductive group G, let I be the set of vertices of the Dynkin diagram of G and T be the maximal torus of G. The structure of a geometric G-crystal on an algebraic variety X consists of a rational morphism \\gamma:X-->T and a compatible family e_i:G_m\\times X-->X, i\\in I of rational actions of the multiplicative group G_m satisfying certain braid-like ...
DEFF Research Database (Denmark)
Bahrami, Bahador; Olsen, Karsten; Bang, Dan;
2011-01-01
were robust and statistically indistinguishable. Taken together, this work demonstrates that social interaction was necessary for build-up of reliable collaborative benefit, whereas objective reference only accelerated the process but-given enough opportunity for practice-was not necessary for building......That objective reference is necessary for formation of reliable beliefs about the external world is almost axiomatic. However, Condorcet (1785) suggested that purely subjective information-if shared and combined via social interaction-is enough for accurate understanding of the external world. We...... asked if social interaction and objective reference contribute differently to the formation and build-up of collective perceptual beliefs. In three experiments, dyads made individual and collective perceptual decisions in a two-interval, forced-choice, visual search task. In Experiment 1, participants...
论网络媒体社会公信力的塑造%On Building up Social Credibility of Network Media
Institute of Scientific and Technical Information of China (English)
陈婉婉
2014-01-01
Strengthening to build up social credibility of network media is a systematic project ,requiring some measures to bet taken including setting up new collection and release mechanism of network media , improving professional quality of network media practitioners ,building up a social credibility brand of net-work media and intensifying public opinions supervision .%加强网络媒体社会公信力的塑造是一个系统工程，需要采取出台系统完善的网络媒体新闻信息采集发布机制，提高网媒从业者的专业素养，打造网媒的社会公信力品牌，以及加强舆论监督等。
Directory of Open Access Journals (Sweden)
Gaurav Jain
2015-01-01
Full Text Available Aim: The in-vitro study compared the shear bond strength (SBS of three recently introduced dual-cure resin based core build-up materials namely ParaCore, FluoroCore, and MultiCore. Materials and Methods: One hundred twenty extracted permanent human mandibular molar teeth were taken and sectioned horizontally beneath the dentinoenamel junction to expose the coronal dentin. The specimens obtained were divided into three main groups based on the materials used and then further divided into four sub-groups based on time interval with ten samples each. The dentin surface was treated with the respective adhesives of the groups and then bulk filled with core build-up materials. The attained samples were than subjected to shear loading in Instron Universal Testing Machine. The data were tabulated and statistically analyzed using analysis of variance (ANOVA, Tukey′s HSD, and Levene′s test. Results: The mean SBS was highest in MultiCore at all time periods as compared to FluoroCore and ParaCore and was also higher at 48 h thermocycling in all three groups studied. Conclusion: MultiCore dual-cure resin based core build-up material showed the highest mean SBS as compared to FluoroCore and ParaCore. SBS was not negatively affected by thermocycling.
Jain, Gaurav; Narad, Aditi; Boruah, Lalit C; Rajkumar, Balakrishnan
2015-01-01
The in-vitro study compared the shear bond strength (SBS) of three recently introduced dual-cure resin based core build-up materials namely ParaCore, FluoroCore, and MultiCore. One hundred twenty extracted permanent human mandibular molar teeth were taken and sectioned horizontally beneath the dentinoenamel junction to expose the coronal dentin. The specimens obtained were divided into three main groups based on the materials used and then further divided into four sub-groups based on time interval with ten samples each. The dentin surface was treated with the respective adhesives of the groups and then bulk filled with core build-up materials. The attained samples were than subjected to shear loading in Instron Universal Testing Machine. The data were tabulated and statistically analyzed using analysis of variance (ANOVA), Tukey's HSD, and Levene's test. The mean SBS was highest in MultiCore at all time periods as compared to FluoroCore and ParaCore and was also higher at 48 h thermocycling in all three groups studied. MultiCore dual-cure resin based core build-up material showed the highest mean SBS as compared to FluoroCore and ParaCore. SBS was not negatively affected by thermocycling.
Geometric and engineering drawing
Morling, K
2010-01-01
The new edition of this successful text describes all the geometric instructions and engineering drawing information that are likely to be needed by anyone preparing or interpreting drawings or designs with plenty of exercises to practice these principles.
Differential geometric structures
Poor, Walter A
2007-01-01
This introductory text defines geometric structure by specifying parallel transport in an appropriate fiber bundle and focusing on simplest cases of linear parallel transport in a vector bundle. 1981 edition.
Bledsoe, Gloria J
1987-01-01
The game of "Guess What" is described as a stimulating vehicle for students to consider the unifying or distinguishing features of geometric figures. Teaching suggestions as well as the gameboard are provided. (MNS)
Saturation and geometrical scaling
Praszalowicz, Michal
2016-01-01
We discuss emergence of geometrical scaling as a consequence of the nonlinear evolution equations of QCD, which generate a new dynamical scale, known as the saturation momentum: Qs. In the kinematical region where no other energy scales exist, particle spectra exhibit geometrical scaling (GS), i.e. they depend on the ratio pT=Qs, and the energy dependence enters solely through the energy dependence of the saturation momentum. We confront the hypothesis of GS in different systems with experimental data.
Geometrical method of decoupling
Directory of Open Access Journals (Sweden)
C. Baumgarten
2012-12-01
Full Text Available The computation of tunes and matched beam distributions are essential steps in the analysis of circular accelerators. If certain symmetries—like midplane symmetry—are present, then it is possible to treat the betatron motion in the horizontal, the vertical plane, and (under certain circumstances the longitudinal motion separately using the well-known Courant-Snyder theory, or to apply transformations that have been described previously as, for instance, the method of Teng and Edwards. In a preceding paper, it has been shown that this method requires a modification for the treatment of isochronous cyclotrons with non-negligible space charge forces. Unfortunately, the modification was numerically not as stable as desired and it was still unclear, if the extension would work for all conceivable cases. Hence, a systematic derivation of a more general treatment seemed advisable. In a second paper, the author suggested the use of real Dirac matrices as basic tools for coupled linear optics and gave a straightforward recipe to decouple positive definite Hamiltonians with imaginary eigenvalues. In this article this method is generalized and simplified in order to formulate a straightforward method to decouple Hamiltonian matrices with eigenvalues on the real and the imaginary axis. The decoupling of symplectic matrices which are exponentials of such Hamiltonian matrices can be deduced from this in a few steps. It is shown that this algebraic decoupling is closely related to a geometric “decoupling” by the orthogonalization of the vectors E[over →], B[over →], and P[over →], which were introduced with the so-called “electromechanical equivalence.” A mathematical analysis of the problem can be traced down to the task of finding a structure-preserving block diagonalization of symplectic or Hamiltonian matrices. Structure preservation means in this context that the (sequence of transformations must be symplectic and hence canonical. When
组合非球面太阳能聚光镜的光学设计%Optical design of build-up aspherical solar concentrating mirror
Institute of Scientific and Technical Information of China (English)
秦华; 冯东太; 葛硕硕; 王勇
2014-01-01
In this paper , a build-up aspherical solar concentrating mirror and its design method are presented . It is composed of 38 pieces of revolution surfaces , and each piece of revolution surface is the part of the as-pheric surface defined by a set of specific coefficients C,a2 ,a4 ,a6 ,a8 ,a10 .According to the even aspherical e-quation and the law of reflection in vector form , the relationship between the direction vectors of rays of light reflected from the inner wall of aspheric surface and the coefficients of an aspherical equation , C,a2 ,a4 ,a6 , a8 ,a10 , has been derived .By appropriately choosing these aspherical coefficients , namely, appropriately ad-justing an aspherical surface type , the reflected light beam can have specific direction vectors , which can make the sunbeams incident on an aspherical inner wall focus on a particular area and form a small spot .Each group of specific coefficients is obtained by using particle swarm optimization algorithm .The focusing effect of the solar concentrating mirror with the specific coefficients is demonstrated by using computer simulations and proved experimentally .The theoretical compression ratio for this concentrating mirror is 330∶1 .The focused spot can be used as a high temperature heat source and the concentrating mirror can be used in a solar heating device .%提出了一种组合非球面反射型太阳能聚光镜并给出了设计方法。聚光镜由38片非球面组成，每一片非球面都由一组特定系数C，a2，a4，a6，a8，a10的偶次非球面方程决定，是此特定非球面的一部分。根据非球面方程和光反射定律矢量形式，导出了非球面内壁上太阳反射光束的方向矢量与非球面系数C，a2，a4，a6，a8，a10的关系，适当地选择这些非球面系数，即适当地调整非球面面型，可以使太阳反射光束具有特定的方向矢量，使入射到非球面内壁上的太阳光束反射后全部聚焦在某一特定的区域
An improved algorithm for cloud multiple scattering
Institute of Scientific and Technical Information of China (English)
Guibin Yuan; Xiaogang Sun; Jingmin Dai
2006-01-01
@@ Clouds' radiation characteristics are very important in clouds scene simulation, weather forecasting, pattern recognition, and other fields. Radiation of a cloud mainly comes from its multiple scattering. A new algorithm to calculate multiple scattering, called build-up factor algorithm, is proposed in this paper. In this algorithm, a modified gamma distribution is assumed to describe droplets distribution inside a cloud, then the radiation transport equation is calculated to get the solution of single scattering, and finally, a build-up factor is defined to estimate the multiple scattering contributions. This algorithm considers both single scattered radiance and multiple scattered radiance and needs shorter computing time. It can be used in real time simulations.
NPP VIIRS Geometric Performance Status
Lin, Guoqing; Wolfe, Robert E.; Nishihama, Masahiro
2011-01-01
Visible Infrared Imager Radiometer Suite (VIIRS) instrument on-board the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP) satellite is scheduled for launch in October, 2011. It is to provide satellite measured radiance/reflectance data for both weather and climate applications. Along with radiometric calibration, geometric characterization and calibration of Sensor Data Records (SDRs) are crucial to the VIIRS Environmental Data Record (EDR) algorithms and products which are used in numerical weather prediction (NWP). The instrument geometric performance includes: 1) sensor (detector) spatial response, parameterized by the dynamic field of view (DFOV) in the scan direction and instantaneous FOV (IFOV) in the track direction, modulation transfer function (MTF) for the 17 moderate resolution bands (M-bands), and horizontal spatial resolution (HSR) for the five imagery bands (I-bands); 2) matrices of band-to-band co-registration (BBR) from the corresponding detectors in all band pairs; and 3) pointing knowledge and stability characteristics that includes scan plane tilt, scan rate and scan start position variations, and thermally induced variations in pointing with respect to orbital position. They have been calibrated and characterized through ground testing under ambient and thermal vacuum conditions, numerical modeling and analysis. This paper summarizes the results, which are in general compliance with specifications, along with anomaly investigations, and describes paths forward for characterizing on-orbit BBR and spatial response, and for improving instrument on-orbit performance in pointing and geolocation.
Geometric systematic prostate biopsy.
Chang, Doyoung; Chong, Xue; Kim, Chunwoo; Jun, Changhan; Petrisor, Doru; Han, Misop; Stoianovici, Dan
2017-04-01
The common sextant prostate biopsy schema lacks a three-dimensional (3D) geometric definition. The study objective was to determine the influence of the geometric distribution of the cores on the detection probability of prostate cancer (PCa). The detection probability of significant (>0.5 cm(3)) and insignificant (geometric distribution of the cores was optimized to maximize the probability of detecting significant cancer for various prostate sizes (20-100cm(3)), number of biopsy cores (6-40 cores) and biopsy core lengths (14-40 mm) for transrectal and transperineal biopsies. The detection of significant cancer can be improved by geometric optimization. With the current sextant biopsy, up to 20% of tumors may be missed at biopsy in a 20 cm(3) prostate due to the schema. Higher number and longer biopsy cores are required to sample with an equal detection probability in larger prostates. Higher number of cores increases both significant and insignificant tumor detection probability, but predominantly increases the detection of insignificant tumors. The study demonstrates mathematically that the geometric biopsy schema plays an important clinical role, and that increasing the number of biopsy cores is not necessarily helpful.
Forward error correction based on algebraic-geometric theory
A Alzubi, Jafar; M Chen, Thomas
2014-01-01
This book covers the design, construction, and implementation of algebraic-geometric codes from Hermitian curves. Matlab simulations of algebraic-geometric codes and Reed-Solomon codes compare their bit error rate using different modulation schemes over additive white Gaussian noise channel model. Simulation results of Algebraic-geometric codes bit error rate performance using quadrature amplitude modulation (16QAM and 64QAM) are presented for the first time and shown to outperform Reed-Solomon codes at various code rates and channel models. The book proposes algebraic-geometric block turbo codes. It also presents simulation results that show an improved bit error rate performance at the cost of high system complexity due to using algebraic-geometric codes and Chase-Pyndiah’s algorithm simultaneously. The book proposes algebraic-geometric irregular block turbo codes (AG-IBTC) to reduce system complexity. Simulation results for AG-IBTCs are presented for the first time.
Geometric Rationalization for Freeform Architecture
Jiang, Caigui
2016-06-20
The emergence of freeform architecture provides interesting geometric challenges with regards to the design and manufacturing of large-scale structures. To design these architectural structures, we have to consider two types of constraints. First, aesthetic constraints are important because the buildings have to be visually impressive. Sec- ond, functional constraints are important for the performance of a building and its e cient construction. This thesis contributes to the area of architectural geometry. Specifically, we are interested in the geometric rationalization of freeform architec- ture with the goal of combining aesthetic and functional constraints and construction requirements. Aesthetic requirements typically come from designers and architects. To obtain visually pleasing structures, they favor smoothness of the building shape, but also smoothness of the visible patterns on the surface. Functional requirements typically come from the engineers involved in the construction process. For exam- ple, covering freeform structures using planar panels is much cheaper than using non-planar ones. Further, constructed buildings have to be stable and should not collapse. In this thesis, we explore the geometric rationalization of freeform archi- tecture using four specific example problems inspired by real life applications. We achieve our results by developing optimization algorithms and a theoretical study of the underlying geometrical structure of the problems. The four example problems are the following: (1) The design of shading and lighting systems which are torsion-free structures with planar beams based on quad meshes. They satisfy the functionality requirements of preventing light from going inside a building as shad- ing systems or reflecting light into a building as lighting systems. (2) The Design of freeform honeycomb structures that are constructed based on hex-dominant meshes with a planar beam mounted along each edge. The beams intersect without
Reconstruction of an InAs nanowire using geometric tomography
DEFF Research Database (Denmark)
Pennington, Robert S.; König, Stefan; Alpers, Andreas;
Geometric tomography and conventional algebraic tomography algorithms are used to reconstruct cross-sections of an InAs nanowire from a tilt series of experimental annular dark-field images. Both algorithms are also applied to a test object to assess what factors affect the reconstruction quality...
Institute of Scientific and Technical Information of China (English)
FuQ满怀; ZhaoZe－bin; 等
1999-01-01
Linked tetra-shaft and double-cantilever flat flap gate is a new type of structure in water conservancy projects,but the traditional method is now adopted in its design.In order to the application and dissemination of the type of sluice,this paper researches the difficult points of design advance,through researching the motion locus & stress coundition of linked tetra-shaft system.The writer will build up the mathmatical model and handle it with the computer.Thus,we can achieve the modern desing on the basis of the software of linked tetra-shaft system development.
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
Linked tetra-shaft and double-cantilever flat flap gate is a new type of structure in water conservancy projects ,but the traditional method is now adopted in its design. In order to the application and dissemination of the type of sluice ,this paper researches the difficult points of design advance ,through researching the mo- tion locus & stress coundition of linked tetra-shaft system. The writer will build up the mathmatical model and handle it with the computer. Thus, we can achieve the modern desing on the basis of the software of linked tetra-shaft system development.
PREFACE: Geometrically frustrated magnetism Geometrically frustrated magnetism
Gardner, Jason S.
2011-04-01
Frustrated magnetism is an exciting and diverse field in condensed matter physics that has grown tremendously over the past 20 years. This special issue aims to capture some of that excitement in the field of geometrically frustrated magnets and is inspired by the 2010 Highly Frustrated Magnetism (HFM 2010) meeting in Baltimore, MD, USA. Geometric frustration is a broad phenomenon that results from an intrinsic incompatibility between some fundamental interactions and the underlying lattice geometry based on triangles and tetrahedra. Most studies have centred around the kagomé and pyrochlore based magnets but recent work has looked at other structures including the delafossite, langasites, hyper-kagomé, garnets and Laves phase materials to name a few. Personally, I hope this issue serves as a great reference to scientist both new and old to this field, and that we all continue to have fun in this very frustrated playground. Finally, I want to thank the HFM 2010 organizers and all the sponsors whose contributions were an essential part of the success of the meeting in Baltimore. Geometrically frustrated magnetism contents Spangolite: an s = 1/2 maple leaf lattice antiferromagnet? T Fennell, J O Piatek, R A Stephenson, G J Nilsen and H M Rønnow Two-dimensional magnetism and spin-size effect in the S = 1 triangular antiferromagnet NiGa2S4 Yusuke Nambu and Satoru Nakatsuji Short range ordering in the modified honeycomb lattice compound SrHo2O4 S Ghosh, H D Zhou, L Balicas, S Hill, J S Gardner, Y Qi and C R Wiebe Heavy fermion compounds on the geometrically frustrated Shastry-Sutherland lattice M S Kim and M C Aronson A neutron polarization analysis study of moment correlations in (Dy0.4Y0.6)T2 (T = Mn, Al) J R Stewart, J M Hillier, P Manuel and R Cywinski Elemental analysis and magnetism of hydronium jarosites—model kagome antiferromagnets and topological spin glasses A S Wills and W G Bisson The Herbertsmithite Hamiltonian: μSR measurements on single crystals
Geometric reconstruction methods for electron tomography
Energy Technology Data Exchange (ETDEWEB)
Alpers, Andreas, E-mail: alpers@ma.tum.de [Zentrum Mathematik, Technische Universität München, D-85747 Garching bei München (Germany); Gardner, Richard J., E-mail: Richard.Gardner@wwu.edu [Department of Mathematics, Western Washington University, Bellingham, WA 98225-9063 (United States); König, Stefan, E-mail: koenig@ma.tum.de [Zentrum Mathematik, Technische Universität München, D-85747 Garching bei München (Germany); Pennington, Robert S., E-mail: robert.pennington@uni-ulm.de [Center for Electron Nanoscopy, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Boothroyd, Chris B., E-mail: ChrisBoothroyd@cantab.net [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Houben, Lothar, E-mail: l.houben@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Dunin-Borkowski, Rafal E., E-mail: rdb@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Joost Batenburg, Kees, E-mail: Joost.Batenburg@cwi.nl [Centrum Wiskunde and Informatica, NL-1098XG, Amsterdam, The Netherlands and Vision Lab, Department of Physics, University of Antwerp, B-2610 Wilrijk (Belgium)
2013-05-15
Electron tomography is becoming an increasingly important tool in materials science for studying the three-dimensional morphologies and chemical compositions of nanostructures. The image quality obtained by many current algorithms is seriously affected by the problems of missing wedge artefacts and non-linear projection intensities due to diffraction effects. The former refers to the fact that data cannot be acquired over the full 180° tilt range; the latter implies that for some orientations, crystalline structures can show strong contrast changes. To overcome these problems we introduce and discuss several algorithms from the mathematical fields of geometric and discrete tomography. The algorithms incorporate geometric prior knowledge (mainly convexity and homogeneity), which also in principle considerably reduces the number of tilt angles required. Results are discussed for the reconstruction of an InAs nanowire. - Highlights: ► Four algorithms for electron tomography are introduced that utilize prior knowledge. ► Objects are assumed to be homogeneous; convexity and regularity is also discussed. ► We are able to reconstruct slices of a nanowire from as few as four projections. ► Algorithms should be selected based on the specific reconstruction task at hand.
Mahavira's Geometrical Problems
DEFF Research Database (Denmark)
Høyrup, Jens
2004-01-01
Analysis of the geometrical chapters Mahavira's 9th-century Ganita-sara-sangraha reveals inspiration from several chronological levels of Near-Eastern and Mediterranean mathematics: (1)that known from Old Babylonian tablets, c. 1800-1600 BCE; (2)a Late Babylonian but pre-Seleucid Stratum, probably...
Burgess, Claudia R.
2014-01-01
Designed for a broad audience, including educators, camp directors, afterschool coordinators, and preservice teachers, this investigation aims to help individuals experience mathematics in unconventional and exciting ways by engaging them in the physical activity of building geometric shapes using ropes. Through this engagement, the author…
Pragmatic geometric model evaluation
Pamer, Robert
2015-04-01
Quantification of subsurface model reliability is mathematically and technically demanding as there are many different sources of uncertainty and some of the factors can be assessed merely in a subjective way. For many practical applications in industry or risk assessment (e. g. geothermal drilling) a quantitative estimation of possible geometric variations in depth unit is preferred over relative numbers because of cost calculations for different scenarios. The talk gives an overview of several factors that affect the geometry of structural subsurface models that are based upon typical geological survey organization (GSO) data like geological maps, borehole data and conceptually driven construction of subsurface elements (e. g. fault network). Within the context of the trans-European project "GeoMol" uncertainty analysis has to be very pragmatic also because of different data rights, data policies and modelling software between the project partners. In a case study a two-step evaluation methodology for geometric subsurface model uncertainty is being developed. In a first step several models of the same volume of interest have been calculated by omitting successively more and more input data types (seismic constraints, fault network, outcrop data). The positions of the various horizon surfaces are then compared. The procedure is equivalent to comparing data of various levels of detail and therefore structural complexity. This gives a measure of the structural significance of each data set in space and as a consequence areas of geometric complexity are identified. These areas are usually very data sensitive hence geometric variability in between individual data points in these areas is higher than in areas of low structural complexity. Instead of calculating a multitude of different models by varying some input data or parameters as it is done by Monte-Carlo-simulations, the aim of the second step of the evaluation procedure (which is part of the ongoing work) is to
Energy Technology Data Exchange (ETDEWEB)
Butson, M.J. E-mail: mbutson@guessmail.com; Cheung Tsang; Yu, P.K.N
2002-04-01
18 MV X-ray beams used in radiotherapy have skin sparing properties as they produce a dose build-up effect whereby a smaller dose is delivered to the skin compared to dose at depth. Experimental results have shown that variations in the build-up dose significantly contribute to lepton contamination produced outside of the patient or the phantom in question. Monte Carlo simulations of 18 MV X-ray beams show that the surface dose contribution from in-phantom scatter alone is approximately 6% of the maximum dose. The contribution to dose from lepton contamination is found by comparison of Monte Carlo phantom photon scatter dose only and experimental data. Results show that the percentage contributions to dose from lepton contamination are approximately, 65%, 90% of dose at 0.05 mm (basal cell layer), 52%, 79% at 1 mm depth (dermal layer) and 15%, 26% at 10 mm depth (subcutaneous tissue) for 10 cmx10 cm{sup 2} and 40 cmx40 cm{sup 2} fields, respectively.
DEFF Research Database (Denmark)
Shafique Bashir, Muhammad; Jensen, Peter Arendt; Jappe Frandsen, Flemming;
This report is about full-scale probe measurements of deposit build-up and removal conducted at the Avedøreværket Unit 2, a 800 MWth suspension boiler, firing wood and natural gas with the addition of coal ash. Coal ash was used as an additive to capture potassium (K) from wood-firing. Investigat......This report is about full-scale probe measurements of deposit build-up and removal conducted at the Avedøreværket Unit 2, a 800 MWth suspension boiler, firing wood and natural gas with the addition of coal ash. Coal ash was used as an additive to capture potassium (K) from wood......-firing. Investigations of deposit formation rate were made by use of an advanced online ash deposition/shedding probe. Quantification of ash deposition and shedding was made via deposit mass uptake signals obtained from the deposit probe. The influence of coal ash, flue gas temperature, probe surface temperature...... and boiler load on ash deposition propensity was investigated. Results of ash deposition propensity showed increasing trend with increasing flue gas temperature. Video monitoring revealed that the deposits formed were not sticky and could be easily removed, and even at very high flue gas temperatures (> 1350...
Križnar, Igor; Jevnikar, Peter; Fidler, Aleš
2015-02-01
The study evaluated the micro push-out bond strength of resin material (Multicore Flow) to two types of fiber posts (FP), namely fiber-reinforced composite (FRC) Postec and Radix Fiber posts using Er:YAG laser pretreatment. FP were divided into four groups, two being control groups. Before the core build-up procedure, representative specimens from each group were chosen to determine the surface roughness (Ra) at three different areas using a contact profilometer, while after the procedure, 1.5-mm-thick discs were sectioned and the micro push-out method was used to assess the bond strength of the core build-up material to the fiber post in each group. Two-way analysis of variance was used for statistical analysis with the level of significance set at p Er:YAG laser pretreatment and to classify the failure mode after loading. The type of pretreatment (p Er:YAG laser pretreatment group was significantly lower compared to the FRC Postec posts control group (p Er:YAG laser pretreatment groups were significantly higher compared to control groups (p Er:YAG laser pretreatment at tested parameters negatively affected the bond strength of Multicore to FP and cannot be recommended as a standard procedure.
Directory of Open Access Journals (Sweden)
Shefali Sawani
2014-01-01
Full Text Available Background: Evaluation of microleakage is important for assessing the success of new restorative materials and methods. Aim and Objectives: Comparative evaluation of microleakage in Class II restorations using open vs. closed centripetal build-up techniques with different lining materials. Materials and Methods: Standardized mesi-occlusal (MO and distoocclusal (DO Class II tooth preparations were preparedon 53 molars and samples were randomly divided into six experimental groups and one control group for restorations. Group 1: Open-Sandwich technique (OST with flowable composite at the gingival seat. Group 2: OST with resin-modified glass ionomer cement (RMGIC at the gingival seat. Group 3: Closed-Sandwich technique (CST with flowable composite at the pulpal floor and axial wall. Group 4: CST with RMGIC at the pulpal floor and axial wall. Group 5: OST with flowable composite at the pulpal floor, axial wall, and gingival seat. Group 6: OST with RMGIC at the pulpal floor, axial wall, and gingival seat. Group 7: Control - no lining material, centripetal technique only. After restorations and thermocycling, apices were sealed and samples were immersed in 0.5% basic fuchsin dye. Sectioning was followed by stereomicroscopic evaluation. Results: Results were analyzed using Post Hoc Bonferroni test (statistics is not a form of tabulation. Cervical scores of control were more than the exprimental groups (P 0.05. Conclusion: Class II composite restorations with centripetal build-up alone or when placed with CST reduces the cervical microleakage when compared to OST.
Institute of Scientific and Technical Information of China (English)
方锡武; 刘振宇; 谭建荣
2011-01-01
在离散元仿真和离散元与有限元耦合问题的前期准备阶段,必须快速在一个指定区域产生互不交迭的、堆积密度尽可能高的颗粒集,以模拟真实的离散状物质.文中针对三维域颗粒集的生成,提出一种几何与物理相结合的颗粒堆积移动模型.首先采用构造法在容器底部产生第一层颗粒.对于后续颗粒的移动方向,其与容器边界接触按物理学弹性碰撞理论计算;与颗粒接触按纯几何方法计算,即以连续2次接触点的法线向量的叉积向量确定新的移动方向,且使新方向有向下的趋势.该模型保证颗粒连续3次接触的目标不同,其稳定态位置快速收敛于3个支撑目标之上,从而满足颗粒静止的物理条件;颗粒间的接触检测基于容器区域规则划分的网格单元,并充分利用颗粒移动模型的特点,根据颗粒的位置和移动方向,按网格层、网格行在网格单元中寻找即将接触的颗粒.实例结果表明,最终产生颗粒集的时间与颗粒数量成线性关系,且颗粒集密度高,耗时也比较短.%In the preparation stage of the discrete element method (DEM) simulation and the coupling of the FEM and the DEM, it is essential to generate a high-density granular assembly in a relatively short time with no overlapping in a specified region to simulate practical granular material. With a combination of geometry and physics, this paper puts forward a particle moving model for packing in 3D region. The model generates the first layer particles on the bottom of the container with the constructive method. Two different methods are adopted to calculate the moving direction of the subsequent particles according to their different contacting condition. If the particle collides with the container boundary, the direction is calculated according to the physical elastic collision theory. If the particle collides with another particle, the direction is calculated with a purely geometrical
Efficient Geometric Sound Propagation Using Visibility Culling
Chandak, Anish
2011-07-01
Simulating propagation of sound can improve the sense of realism in interactive applications such as video games and can lead to better designs in engineering applications such as architectural acoustics. In this thesis, we present geometric sound propagation techniques which are faster than prior methods and map well to upcoming parallel multi-core CPUs. We model specular reflections by using the image-source method and model finite-edge diffraction by using the well-known Biot-Tolstoy-Medwin (BTM) model. We accelerate the computation of specular reflections by applying novel visibility algorithms, FastV and AD-Frustum, which compute visibility from a point. We accelerate finite-edge diffraction modeling by applying a novel visibility algorithm which computes visibility from a region. Our visibility algorithms are based on frustum tracing and exploit recent advances in fast ray-hierarchy intersections, data-parallel computations, and scalable, multi-core algorithms. The AD-Frustum algorithm adapts its computation to the scene complexity and allows small errors in computing specular reflection paths for higher computational efficiency. FastV and our visibility algorithm from a region are general, object-space, conservative visibility algorithms that together significantly reduce the number of image sources compared to other techniques while preserving the same accuracy. Our geometric propagation algorithms are an order of magnitude faster than prior approaches for modeling specular reflections and two to ten times faster for modeling finite-edge diffraction. Our algorithms are interactive, scale almost linearly on multi-core CPUs, and can handle large, complex, and dynamic scenes. We also compare the accuracy of our sound propagation algorithms with other methods. Once sound propagation is performed, it is desirable to listen to the propagated sound in interactive and engineering applications. We can generate smooth, artifact-free output audio signals by applying
Frè, Pietro Giuseppe
2013-01-01
‘Gravity, a Geometrical Course’ presents general relativity (GR) in a systematic and exhaustive way, covering three aspects that are homogenized into a single texture: i) the mathematical, geometrical foundations, exposed in a self consistent contemporary formalism, ii) the main physical, astrophysical and cosmological applications, updated to the issues of contemporary research and observations, with glimpses on supergravity and superstring theory, iii) the historical development of scientific ideas underlying both the birth of general relativity and its subsequent evolution. The book is divided in two volumes. Volume One is dedicated to the development of the theory and basic physical applications. It guides the reader from the foundation of special relativity to Einstein field equations, illustrating some basic applications in astrophysics. A detailed account of the historical and conceptual development of the theory is combined with the presentation of its mathematical foundations. Differe...
Bestvina, Mladen; Vogtmann, Karen
2014-01-01
Geometric group theory refers to the study of discrete groups using tools from topology, geometry, dynamics and analysis. The field is evolving very rapidly and the present volume provides an introduction to and overview of various topics which have played critical roles in this evolution. The book contains lecture notes from courses given at the Park City Math Institute on Geometric Group Theory. The institute consists of a set of intensive short courses offered by leaders in the field, designed to introduce students to exciting, current research in mathematics. These lectures do not duplicate standard courses available elsewhere. The courses begin at an introductory level suitable for graduate students and lead up to currently active topics of research. The articles in this volume include introductions to CAT(0) cube complexes and groups, to modern small cancellation theory, to isometry groups of general CAT(0) spaces, and a discussion of nilpotent genus in the context of mapping class groups and CAT(0) gro...
Dynamics in geometrical confinement
Kremer, Friedrich
2014-01-01
This book describes the dynamics of low molecular weight and polymeric molecules when they are constrained under conditions of geometrical confinement. It covers geometrical confinement in different dimensionalities: (i) in nanometer thin layers or self supporting films (1-dimensional confinement) (ii) in pores or tubes with nanometric diameters (2-dimensional confinement) (iii) as micelles embedded in matrices (3-dimensional) or as nanodroplets.The dynamics under such conditions have been a much discussed and central topic in the focus of intense worldwide research activities within the last two decades. The present book discusses how the resulting molecular mobility is influenced by the subtle counterbalance between surface effects (typically slowing down molecular dynamics through attractive guest/host interactions) and confinement effects (typically increasing the mobility). It also explains how these influences can be modified and tuned, e.g. through appropriate surface coatings, film thicknesses or pore...
Geometric Time Delay Interferometry
Vallisneri, Michele
2005-01-01
The space-based gravitational-wave observatory LISA, a NASA-ESA mission to be launched after 2012, will achieve its optimal sensitivity using Time Delay Interferometry (TDI), a LISA-specific technique needed to cancel the otherwise overwhelming laser noise in the inter-spacecraft phase measurements. The TDI observables of the Michelson and Sagnac types have been interpreted physically as the virtual measurements of a synthesized interferometer. In this paper, I present Geometric TDI, a new an...
Geometric unsharpness calculations
Energy Technology Data Exchange (ETDEWEB)
Anderson, D.J. [International Training and Education Group (INTEG), Oakville, Ontario (Canada)
2008-07-15
The majority of radiographers' geometric unsharpness calculations are normally performed with a mathematical formula. However, a majority of codes and standards refer to the use of a nomograph for this calculation. Upon first review, the use of a nomograph appears more complicated but with a few minutes of study and practice it can be just as effective. A review of this article should provide enlightenment. (author)
Geometric Stochastic Resonance
Ghosh, Pulak Kumar; Savel'ev, Sergey E; Nori, Franco
2015-01-01
A Brownian particle moving across a porous membrane subject to an oscillating force exhibits stochastic resonance with properties which strongly depend on the geometry of the confining cavities on the two sides of the membrane. Such a manifestation of stochastic resonance requires neither energetic nor entropic barriers, and can thus be regarded as a purely geometric effect. The magnitude of this effect is sensitive to the geometry of both the cavities and the pores, thus leading to distinctive optimal synchronization conditions.
Geometric properties of eigenfunctions
Energy Technology Data Exchange (ETDEWEB)
Jakobson, D; Nadirashvili, N [McGill University, Montreal, Quebec (Canada); Toth, John [University of Chicago, Chicago, Illinois (United States)
2001-12-31
We give an overview of some new and old results on geometric properties of eigenfunctions of Laplacians on Riemannian manifolds. We discuss properties of nodal sets and critical points, the number of nodal domains, and asymptotic properties of eigenfunctions in the high-energy limit (such as weak * limits, the rate of growth of L{sup p} norms, and relationships between positive and negative parts of eigenfunctions)
Geometric theory of information
2014-01-01
This book brings together geometric tools and their applications for Information analysis. It collects current and many uses of in the interdisciplinary fields of Information Geometry Manifolds in Advanced Signal, Image & Video Processing, Complex Data Modeling and Analysis, Information Ranking and Retrieval, Coding, Cognitive Systems, Optimal Control, Statistics on Manifolds, Machine Learning, Speech/sound recognition, and natural language treatment which are also substantially relevant for the industry.
Perspective: Geometrically frustrated assemblies
Grason, Gregory M.
2016-09-01
This perspective will overview an emerging paradigm for self-organized soft materials, geometrically frustrated assemblies, where interactions between self-assembling elements (e.g., particles, macromolecules, proteins) favor local packing motifs that are incompatible with uniform global order in the assembly. This classification applies to a broad range of material assemblies including self-twisting protein filament bundles, amyloid fibers, chiral smectics and membranes, particle-coated droplets, curved protein shells, and phase-separated lipid vesicles. In assemblies, geometric frustration leads to a host of anomalous structural and thermodynamic properties, including heterogeneous and internally stressed equilibrium structures, self-limiting assembly, and topological defects in the equilibrium assembly structures. The purpose of this perspective is to (1) highlight the unifying principles and consequences of geometric frustration in soft matter assemblies; (2) classify the known distinct modes of frustration and review corresponding experimental examples; and (3) describe outstanding questions not yet addressed about the unique properties and behaviors of this broad class of systems.
Lloyd, Seth
2012-01-01
This letter analyzes the limits that quantum mechanics imposes on the accuracy to which spacetime geometry can be measured. By applying the fundamental physical bounds to measurement accuracy to ensembles of clocks and signals moving in curved spacetime -- e.g., the global positioning system -- I derive a covariant version of the quantum geometric limit: the total number of ticks of clocks and clicks of detectors that can be contained in a four volume of spacetime of radius r and temporal extent t is less than or equal to rt/\\pi x_P t_P, where x_P, t_P are the Planck length and time. The quantum geometric limit bounds the number of events or `ops' that can take place in a four-volume of spacetime: each event is associated with a Planck-scale area. Conversely, I show that if each quantum event is associated with such an area, then Einstein's equations must hold. The quantum geometric limit is consistent with and complementary to the holographic bound which limits the number of bits that can exist within a spat...
Geometric diffusion of quantum trajectories.
Yang, Fan; Liu, Ren-Bao
2015-07-16
A quantum object can acquire a geometric phase (such as Berry phases and Aharonov-Bohm phases) when evolving along a path in a parameter space with non-trivial gauge structures. Inherent to quantum evolutions of wavepackets, quantum diffusion occurs along quantum trajectories. Here we show that quantum diffusion can also be geometric as characterized by the imaginary part of a geometric phase. The geometric quantum diffusion results from interference between different instantaneous eigenstate pathways which have different geometric phases during the adiabatic evolution. As a specific example, we study the quantum trajectories of optically excited electron-hole pairs in time-reversal symmetric insulators, driven by an elliptically polarized terahertz field. The imaginary geometric phase manifests itself as elliptical polarization in the terahertz sideband generation. The geometric quantum diffusion adds a new dimension to geometric phases and may have applications in many fields of physics, e.g., transport in topological insulators and novel electro-optical effects.
Algebraic geometric codes with applications
Institute of Scientific and Technical Information of China (English)
CHEN Hao
2007-01-01
The theory of linear error-correcting codes from algebraic geomet-ric curves (algebraic geometric (AG) codes or geometric Goppa codes) has been well-developed since the work of Goppa and Tsfasman, Vladut, and Zink in 1981-1982. In this paper we introduce to readers some recent progress in algebraic geometric codes and their applications in quantum error-correcting codes, secure multi-party computation and the construction of good binary codes.
Geometric correction of deformed chromosomes for automatic Karyotyping.
Khan, Shadab; DSouza, Alisha; Sanches, João; Ventura, Rodrigo
2012-01-01
Automatic Karyotyping is the process of classifying chromosomes from an unordered karyogram into their respective classes to create an ordered karyogram. Automatic karyotyping algorithms typically perform geometrical correction of deformed chromosomes for feature extraction; these features are used by classifier algorithms for classifying the chromosomes. Karyograms of bone marrow cells are known to have poor image quality. An example of such karyograms is the Lisbon-K(1) (LK(1)) dataset that is used in our work. Thus, to correct the geometrical deformation of chromosomes from LK(1), a robust method to obtain the medial axis of the chromosome was necessary. To address this problem, we developed an algorithm that uses the seed points to make a primary prediction. Subsequently, the algorithm computes the distance of boundary from the predicted point, and the gradients at algorithm-specified points on the boundary to compute two auxiliary predictions. Primary prediction is then corrected using auxiliary predictions, and a final prediction is obtained to be included in the seed region. A medial axis is obtained this way, which is further used for geometrical correction of the chromosomes. This algorithm was found capable of correcting geometrical deformations in even highly distorted chromosomes with forked ends.
Deformable image registration with geometric changes
Institute of Scientific and Technical Information of China (English)
Yu LIU; Bo ZHU
2015-01-01
Geometric changes present a number of difficulties in deformable image registration. In this paper, we propose a global deformation framework to model geometric changes whilst promoting a smooth transformation between source and target images. To achieve this, we have developed an innovative model which significantly reduces the side effects of geometric changes in image registration, and thus improves the registration accuracy. Our key contribution is the introduction of a sparsity-inducing norm, which is typically L1 norm regularization targeting regions where geometric changes occur. This preserves the smoothness of global transformation by eliminating local transformation under different conditions. Numerical solutions are discussed and analyzed to guarantee the stability and fast convergence of our algorithm. To demonstrate the effectiveness and utility of this method, we evaluate it on both synthetic data and real data from traumatic brain injury (TBI). We show that the transformation estimated from our model is able to reconstruct the target image with lower instances of error than a standard elastic registration model.
Song, Xiaoye; McDonald, James; Price, William E; Khan, Stuart J; Hai, Faisal I; Ngo, Hao H; Guo, Wenshan; Nghiem, Long D
2016-09-01
The effects of elevated inorganic salt concentration on anaerobic membrane bioreactor (AnMBR) treatment regarding basic biological performance and trace organic contaminant (TrOC) removal were investigated. A set of 33 TrOCs were selected to represent pharmaceuticals, steroids, and pesticides in municipal wastewater. Results show potential adverse effects of increase in the bioreactor salinity to 15g/L (as NaCl) on the performance of AnMBR with respect to chemical oxygen demand removal, biogas production, and the removal of most hydrophilic TrOCs. Furthermore, a decrease in biomass production was observed as salinity in the bioreactor increased. The removal of most hydrophobic TrOCs was high and was not significantly affected by salinity build-up in the bioreactor. The accumulation of a few persistent TrOCs in the sludge phase was observed, but such accumulation did not vary significantly as salinity in the bioreactor increased.
Jbara, O; Belhaj, M; Cazaux, J; Rau, E I; Filippov, M; Andrianov, M V
2002-01-01
An original method is proposed to investigate the dynamical trapping properties of bulk insulators during their irradiation by keV electrons when they are coated with a grounded metallic film. This method is based on the measurement of the displacement current and it allows to evaluate time constants for charging and discharging the dielectric as well as to evaluate the electric field build up and trapped charge density below the coating. This method is illustrated by the estimate of the charging and discharging time constants in e sup - irradiated PMMA and the estimate of the magnitude of the electric field which drives the migration of the mobile ions in e sup - irradiated glasses.
A practical guide to geometric regulation for distributed parameter systems
Aulisa, Eugenio
2015-01-01
A Practical Guide to Geometric Regulation for Distributed Parameter Systems provides an introduction to geometric control design methodologies for asymptotic tracking and disturbance rejection of infinite-dimensional systems. The book also introduces several new control algorithms inspired by geometric invariance and asymptotic attraction for a wide range of dynamical control systems. The first part of the book is devoted to regulation of linear systems, beginning with the mathematical setup, general theory, and solution strategy for regulation problems with bounded input and output operators.
Fuzzy Clustering Using the Convex Hull as Geometrical Model
Directory of Open Access Journals (Sweden)
Luca Liparulo
2015-01-01
Full Text Available A new approach to fuzzy clustering is proposed in this paper. It aims to relax some constraints imposed by known algorithms using a generalized geometrical model for clusters that is based on the convex hull computation. A method is also proposed in order to determine suitable membership functions and hence to represent fuzzy clusters based on the adopted geometrical model. The convex hull is not only used at the end of clustering analysis for the geometric data interpretation but also used during the fuzzy data partitioning within an online sequential procedure in order to calculate the membership function. Consequently, a pure fuzzy clustering algorithm is obtained where clusters are fitted to the data distribution by means of the fuzzy membership of patterns to each cluster. The numerical results reported in the paper show the validity and the efficacy of the proposed approach with respect to other well-known clustering algorithms.
Study on geometric correction of airborne multiangular imagery
Institute of Scientific and Technical Information of China (English)
LIU; Qiang; (刘强); LIU; Qinhuo; (柳钦火); XIAO; Qing; (肖青); TIAN; Guoliang; (田国良)
2002-01-01
An automatic image matching algorithm, and its application to geometric correction of airborne multiangular remote sensed imagery, are presented in this paper. The image-matching algorithm is designed to find correct match for images containing localized geometric distortion and spectral variation. Mathematical tools such as wavelet decomposition, B-spline, and multi-variant correlation estimator are integrated in the frame of pyramidal matching. The simulated experiment and our practice in correcting airborne multiangular images show that the matching algorithm is robust to the few random abnormal points and can achieve subpixel match accuracy in most area of the image. After geometric correction and registration, multiangular observations for each ground pixel are extracted and sun/view geometry is also simultaneously derived.
Energy Technology Data Exchange (ETDEWEB)
Maekelae, K.; Laitinen, T.; Bojinov, M. [VTT Manufacturing Technology, Espoo (Finland)
1999-03-01
The primary coolant oxidises the surfaces of construction materials in nuclear power plants. The properties of the oxide films influence significantly the extent of incorporation of actuated corrosion products into the primary circuit surfaces, which may cause additional occupational doses for the maintenance personnel. The physical and chemical properties of the oxide films play also an important role in different forms of corrosion observed in power plants. This report gives a short overview of the factors influencing activity build-up and corrosion phenomena in nuclear power plants. Furthermore, the most recent modifications in the water chemistry to decrease these risks are discussed. A special focus is put on zinc water chemistry, and a preliminary discussion on the mechanism via which zinc influences activity build-up is presented. Even though the exact mechanisms by which zinc acts are not yet known, it is assumed that Zn may block the diffusion paths within the oxide film. This reduces ion transport through the oxide films leading to a reduced rate of oxide growth. Simultaneously the number of available adsorption sites for {sup 60}Co is also reduced. The current models for stress corrosion cracking assume that the anodic and the respective cathodic reactions contributing to crack growth occur partly on or in the oxide films. The rates of these reactions may control the crack propagation rate and therefore, the properties of the oxide films play a crucial role in determining the susceptibility of the material to stress corrosion cracking. Finally, attention is paid also on the novel techniques which can be used to mitigate the susceptibility of construction materials to stress corrosion cracking. (orig.) 127 refs.
Gallego, Jesús; Prieto, Mercedes; Eliche-Moral, M. Carmen; Balcells, Marc; Cristóbal-Hornillos, David; Erwin, Peter; Abreu, David; Domínguez-Palmero, Lilian; Hempel, Angela; López-Sanjuan, Carlos; Guzmán, Rafael; Pérez-González, Pablo G.; Barro, Guillermo; Zamorano, Jaime
2013-07-01
Some recent observations seem to disagree with hierarchical theories of galaxy formation on the role of major mergers in a late build-up of massive early-type galaxies. We re-address this question by analysing the morphology, structural distortion level, and star formation enhancement of a sample of massive galaxies (M* > 5 × 1010M⊙) lying on the Red Sequence and its surroundings at 0.3 migrated to the Red Sequence majoritarily through major mergers at 0.6 1011M⊙ at z = 0 through gas-rich major mergers has frozen since z ~ 0.6. Our results support that major mergers have played the dominant role in the definitive build-up of present-day E-S0's with M* > 1011M⊙ at 0.6 < z < 1.2, in good agreement with the hierarchical scenario proposed in the Eliche-Moral et al. (2010a) model (see also Eliche-Moral et al. 2010b). This study is published in Prieto et al. (2012). Supported by the Spanish Ministry of Science and Innovation (MICINN) under projects AYA2009-10368, AYA2006-12955, AYA2010-21887-C04-04, and AYA2009-11137, by the Madrid Regional Government through the AstroMadrid Project (CAM S2009/ESP-1496), and by the Spanish MICINN under the Consolider-Ingenio 2010 Program grant CSD2006-00070: ``First Science with the GTC'' (http://www.iac.es/consolider-ingenio-gtc/). S. D. H. & G.
Geometric Number Systems and Spinors
Sobczyk, Garret
2015-01-01
The real number system is geometrically extended to include three new anticommuting square roots of plus one, each such root representing the direction of a unit vector along the orthonormal coordinate axes of Euclidean 3-space. The resulting geometric (Clifford) algebra provides a geometric basis for the famous Pauli matrices which, in turn, proves the consistency of the rules of geometric algebra. The flexibility of the concept of geometric numbers opens the door to new understanding of the nature of space-time, and of Pauli and Dirac spinors as points on the Riemann sphere, including Lorentz boosts.
Ambrosetti, Antonio; Malchiodi, Andrea
2009-01-01
This volume contains lecture notes on some topics in geometric analysis, a growing mathematical subject which uses analytical techniques, mostly of partial differential equations, to treat problems in differential geometry and mathematical physics. The presentation of the material should be rather accessible to non-experts in the field, since the presentation is didactic in nature. The reader will be provided with a survey containing some of the most exciting topics in the field, with a series of techniques used to treat such problems.
Bose, Prosenjit; Morin, Pat; Smid, Michiel
2012-01-01
Highly connected and yet sparse graphs (such as expanders or graphs of high treewidth) are fundamental, widely applicable and extensively studied combinatorial objects. We initiate the study of such highly connected graphs that are, in addition, geometric spanners. We define a property of spanners called robustness. Informally, when one removes a few vertices from a robust spanner, this harms only a small number of other vertices. We show that robust spanners must have a superlinear number of edges, even in one dimension. On the positive side, we give constructions, for any dimension, of robust spanners with a near-linear number of edges.
Shapere, Alfred D
1989-01-01
During the last few years, considerable interest has been focused on the phase that waves accumulate when the equations governing the waves vary slowly. The recent flurry of activity was set off by a paper by Michael Berry, where it was found that the adiabatic evolution of energy eigenfunctions in quantum mechanics contains a phase of geometric origin (now known as 'Berry's phase') in addition to the usual dynamical phase derived from Schrödinger's equation. This observation, though basically elementary, seems to be quite profound. Phases with similar mathematical origins have been identified
Geometric modeling of subcellular structures, organelles, and multiprotein complexes
Feng, Xin; Xia, Kelin; Tong, Yiying; Wei, Guo-Wei
2013-01-01
SUMMARY Recently, the structure, function, stability, and dynamics of subcellular structures, organelles, and multi-protein complexes have emerged as a leading interest in structural biology. Geometric modeling not only provides visualizations of shapes for large biomolecular complexes but also fills the gap between structural information and theoretical modeling, and enables the understanding of function, stability, and dynamics. This paper introduces a suite of computational tools for volumetric data processing, information extraction, surface mesh rendering, geometric measurement, and curvature estimation of biomolecular complexes. Particular emphasis is given to the modeling of cryo-electron microscopy data. Lagrangian-triangle meshes are employed for the surface presentation. On the basis of this representation, algorithms are developed for surface area and surface-enclosed volume calculation, and curvature estimation. Methods for volumetric meshing have also been presented. Because the technological development in computer science and mathematics has led to multiple choices at each stage of the geometric modeling, we discuss the rationales in the design and selection of various algorithms. Analytical models are designed to test the computational accuracy and convergence of proposed algorithms. Finally, we select a set of six cryo-electron microscopy data representing typical subcellular complexes to demonstrate the efficacy of the proposed algorithms in handling biomolecular surfaces and explore their capability of geometric characterization of binding targets. This paper offers a comprehensive protocol for the geometric modeling of subcellular structures, organelles, and multiprotein complexes. PMID:23212797
Geometric Correction for Braille Document Images
Directory of Open Access Journals (Sweden)
Padmavathi.S
2016-04-01
Full Text Available Braille system has been used by the visually impair ed people for reading.The shortage of Braille books has caused a need for conversion of Braille t o text. This paper addresses the geometric correction of a Braille document images. Due to the standard measurement of the Braille cells, identification of Braille characters could be achie ved by simple cell overlapping procedure. The standard measurement varies in a scaled document an d fitting of the cells become difficult if the document is tilted. This paper proposes a line fitt ing algorithm for identifying the tilt (skew angle. The horizontal and vertical scale factor is identified based on the ratio of distance between characters to the distance between dots. Th ese are used in geometric transformation matrix for correction. Rotation correction is done prior to scale correction. This process aids in increased accuracy. The results for various Braille documents are tabulated.
Geometric description of images as topographic maps
Caselles, Vicent
2010-01-01
This volume discusses the basic geometric contents of an image and presents a tree data structure to handle those contents efficiently. The nodes of the tree are derived from connected components of level sets of the intensity, while the edges represent inclusion information. Grain filters, morphological operators simplifying these geometric contents, are analyzed and several applications to image comparison and registration, and to edge and corner detection, are presented. The mathematically inclined reader may be most interested in Chapters 2 to 6, which generalize the topological Morse description to continuous or semicontinuous functions, while mathematical morphologists may more closely consider grain filters in Chapter 3. Computer scientists will find algorithmic considerations in Chapters 6 and 7, the full justification of which may be found in Chapters 2 and 4 respectively. Lastly, all readers can learn more about the motivation for this work in the image processing applications presented in Chapter 8...
Simulating geometrically complex blast scenarios
Directory of Open Access Journals (Sweden)
Ian G. Cullis
2016-04-01
Full Text Available The effects of blast waves generated by energetic and non-energetic sources are of continuing interest to the ballistics research community. Modern conflicts are increasingly characterised by asymmetric urban warfare, with improvised explosive devices (IEDs often playing a dominant role on the one hand and an armed forces requirement for minimal collateral effects from their weapons on the other. These problems are characterised by disparate length- and time-scales and may also be governed by complex physics. There is thus an increasing need to be able to rapidly assess and accurately predict the effects of energetic blast in topologically complex scenarios. To this end, this paper presents a new QinetiQ-developed advanced computational package called EAGLE-Blast, which is capable of accurately resolving the generation, propagation and interaction of blast waves around geometrically complex shapes such as vehicles and buildings. After a brief description of the numerical methodology, various blast scenario simulations are described and the results compared with experimental data to demonstrate the validation of the scheme and its ability to describe these complex scenarios accurately and efficiently. The paper concludes with a brief discussion on the use of the code in supporting the development of algorithms for fast running engineering models.
Simulating geometrically complex blast scenarios
Institute of Scientific and Technical Information of China (English)
Ian G. CULLIS; Nikos NIKIFORAKIS; Peter FRANKL; Philip BLAKELY; Paul BENNETT; Paul GREENWOOD
2016-01-01
The effects of blast waves generated by energetic and non-energetic sources are of continuing interest to the ballistics research community. Modern conflicts are increasingly characterised by asymmetric urban warfare, with improvised explosive devices (IEDs) often playing a dominant role on the one hand and an armed forces requirement for minimal collateral effects from their weapons on the other. These problems are characterised by disparate length-and time-scales and may also be governed by complex physics. There is thus an increasing need to be able to rapidly assess and accurately predict the effects of energetic blast in topologically complex scenarios. To this end, this paper presents a new QinetiQ-developed advanced computational package called EAGLE-Blast, which is capable of accurately resolving the generation, propagation and interaction of blast waves around geometrically complex shapes such as vehicles and buildings. After a brief description of the numerical methodology, various blast scenario simulations are described and the results compared with experimental data to demonstrate the validation of the scheme and its ability to describe these complex scenarios accurately and efficiently. The paper concludes with a brief discussion on the use of the code in supporting the development of algorithms for fast running engineering models.
Geometric registration and rectification of spaceborne SAR imagery
Curlander, J. C.; Pang, S. N.
1982-01-01
This paper describes the development of automated location and geometric rectification techniques for digitally processed synthetic aperture radar (SAR) imagery. A software package has been developed that is capable of determining the absolute location of an image pixel to within 60 m using only the spacecraft ephemeris data and the characteristics of the SAR data collection and processing system. Based on this location capability algorithms have been developed that geometrically rectify the imagery, register it to a common coordinate system and mosaic multiple frames to form extended digital SAR maps. These algorithms have been optimized using parallel processing techniques to minimize the operating time. Test results are given using Seasat SAR data.
Computing the Expected Value and Variance of Geometric Measures
DEFF Research Database (Denmark)
Staals, Frank; Tsirogiannis, Constantinos
2017-01-01
points in P. This problem is a crucial part of modern ecological analyses; each point in P represents a species in d-dimensional trait space, and the goal is to compute the statistics of a geometric measure on this trait space, when subsets of species are selected under random processes. We present...... efficient exact algorithms for computing the mean and variance of several geometric measures when point sets are selected under one of the described random distributions. More specifically, we provide algorithms for the following measures: the bounding box volume, the convex hull volume, the mean pairwise...
Directory of Open Access Journals (Sweden)
Rolando Rivero-Galán
2010-01-01
Full Text Available ResumenEn la esfera del diseno de estructuras y de elementos de maquinas, se presenta con relativafrecuencia el calculo de determinadas caracteristicas o propiedades geometricas de seccionesplanas, como son entre otras: el area de una seccion transversal, el centro de gravedad, unmomento de inercia o mas general la determinacion de alguna caracteristica geometrica definidapor una integral doble extendida en la region del plano que ocupa la seccion, pieza o elemento.El presente trabajo tiene como objetivo la confeccion de un programa para computadora,utilizando el asistente matematico DERIVE, para la determinacion de las caracteristicas geometricasde secciones planas cuyo contorno este constituido por segmentos de rectas.Palabras claves: Algoritmo, seccion plana, DERIVE, momentos, centro de gravedad.______________________________________________________________AbstractIn the sphere of the design of structures, is relative frequency the calculation of certaincharacteristic or geometric properties of plane sections, like: the area of a traverse section, thecenter of gravity, a moment of inertia or more general the determination of some geometriccharacteristic defined by a double integral extended in the region of the plane that occupies thesection, piece or element.The present work has as objective the making of a program for computer, using the mathematicalassistant DERIVE, for the determination of the geometric characteristics of plane sections whosecontour this constituted by segments of right.Key words: Algorithm, plane section, DERIVE, moments, center of gravity
Algorithms in Algebraic Geometry
Dickenstein, Alicia; Sommese, Andrew J
2008-01-01
In the last decade, there has been a burgeoning of activity in the design and implementation of algorithms for algebraic geometric computation. Some of these algorithms were originally designed for abstract algebraic geometry, but now are of interest for use in applications and some of these algorithms were originally designed for applications, but now are of interest for use in abstract algebraic geometry. The workshop on Algorithms in Algebraic Geometry that was held in the framework of the IMA Annual Program Year in Applications of Algebraic Geometry by the Institute for Mathematics and Its
License plate detection algorithm
Broitman, Michael; Klopovsky, Yuri; Silinskis, Normunds
2013-12-01
A novel algorithm for vehicle license plates localization is proposed. The algorithm is based on pixel intensity transition gradient analysis. Near to 2500 natural-scene gray-level vehicle images of different backgrounds and ambient illumination was tested. The best set of algorithm's parameters produces detection rate up to 0.94. Taking into account abnormal camera location during our tests and therefore geometrical distortion and troubles from trees this result could be considered as passable. Correlation between source data, such as license Plate dimensions and texture, cameras location and others, and parameters of algorithm were also defined.
Geometric Complexity Theory: Introduction
Sohoni, Ketan D Mulmuley Milind
2007-01-01
These are lectures notes for the introductory graduate courses on geometric complexity theory (GCT) in the computer science department, the university of Chicago. Part I consists of the lecture notes for the course given by the first author in the spring quarter, 2007. It gives introduction to the basic structure of GCT. Part II consists of the lecture notes for the course given by the second author in the spring quarter, 2003. It gives introduction to invariant theory with a view towards GCT. No background in algebraic geometry or representation theory is assumed. These lecture notes in conjunction with the article \\cite{GCTflip1}, which describes in detail the basic plan of GCT based on the principle called the flip, should provide a high level picture of GCT assuming familiarity with only basic notions of algebra, such as groups, rings, fields etc.
The Geometric Transition Revisited
Gwyn, Rhiannon
2007-01-01
Our intention in this article is to review known facts and to summarise recent advances in the understanding of geometric transitions and the underlying open/closed duality in string theory. We aim to present a pedagogical discussion of the gauge theory underlying the Klebanov--Strassler model and review the Gopakumar--Vafa conjecture based on topological string theory. These models are also compared in the T-dual brane constructions. We then summarise a series of papers verifying both models on the supergravity level. An appendix provides extensive background material about conifold geometries. We pay special attention to their complex structures and re-evaluate the supersymmetry conditions on the background flux in constructions with fractional D3-branes on the singular (Klebanov--Strassler) and resolved (Pando Zayas--Tseytlin) conifolds. We agree with earlier results that only the singular solution allows a supersymmetric flux, but point out the importance of using the correct complex structure to reach th...
Kahle, Matthew
2009-01-01
We study the expected topological properties of Cech and Vietoris-Rips complexes built on randomly sampled points in R^d. These are, in some cases, analogues of known results for connectivity and component counts for random geometric graphs. However, an important difference in this setting is that homology is not monotone in the underlying parameter. In the sparse range, we compute the expectation and variance of the Betti numbers, and establish Central Limit Theorems and concentration of measure. In the dense range, we introduce Morse theoretic arguments to bound the expectation of the Betti numbers, which is the main technical contribution of this article. These results provide a detailed probabilistic picture to compare with the topological statistics of point cloud data.
Geometrical Destabilization of Inflation
Renaux-Petel, Sébastien; Turzyński, Krzysztof
2016-09-01
We show the existence of a general mechanism by which heavy scalar fields can be destabilized during inflation, relying on the fact that the curvature of the field space manifold can dominate the stabilizing force from the potential and destabilize inflationary trajectories. We describe a simple and rather universal setup in which higher-order operators suppressed by a large energy scale trigger this instability. This phenomenon can prematurely end inflation, thereby leading to important observational consequences and sometimes excluding models that would otherwise perfectly fit the data. More generally, it modifies the interpretation of cosmological constraints in terms of fundamental physics. We also explain how the geometrical destabilization can lead to powerful selection criteria on the field space curvature of inflationary models.
Group Leaders Optimization Algorithm
Daskin, Anmer
2010-01-01
Complexity of global optimization algorithms makes implementation of the algorithms difficult and leads the algorithms to require more computer resources for the optimization process. The ability to explore the whole solution space without increasing the complexity of algorithms has a great importance to not only get reliable results but so also make the implementation of these algorithms more convenient for higher dimensional and complex-real world problems in science and engineering. In this paper, we present a new global optimization algorithm in which the influence of the leaders in social groups is used as an inspiration for the evolutionary technique that is designed into a group architecture similar to the architecture of Cooperative Coevolutionary Algorithms. Therefore, we present the implementation method and the experimental results for the single and multidimensional optimization test problems and a scientific real world problem, the energies and the geometric structures of Lennard-Jones clusters.
Castro Videla, Fernando; Barnaba, Francesca; Angelini, Federico; Cremades, Pablo; Gobbi, Gian Paolo
2013-03-01
In South America (SA) biomass burning is the major source of atmospheric aerosols. Fires are mostly registered in the dry season (July-November) and are mainly concentrated in the Amazonia and Cerrado regions. Nonetheless, the growing systematic employment of fires for land clearing and pasture maintenance across the SA continent is introducing other, potentially significant, sources of BB aerosols. This study investigates the relative contributions of different SA biomass burning regions in building up the continental aerosol load. To this purpose, the SA continent is divided into four biomass burning source regions and their impact on the aerosol optical depth (AOD) is evaluated in eight different SA target domains. The dataset used includes multi-year (2005-2009) satellite observations of both aerosol and fires and model-based atmospheric trajectories. The methodology followed couples fire counts and atmospheric transport through the definition of a specific quantity, referred to as ‘fire weighted residence time’ (FWRT), which is used to assess the contribution of the four identified fire source regions to the continental aerosol load. Results show that local fires play an important role in building up the regional aerosols load all over SA. Nevertheless, in some regions, contribution of BB aerosols transported from outside their boundaries is comparable to the local one. The major ‘smoke exporter’ regions are found to be the eastern Brazil and the Amazonia-Cerrado regions. In the dry season, due to the typical continental circulation pattern, the first is estimated to contribute to half of the AOD in Northern Amazonia, Southern Amazonia and Cerrado regions, while over 30% of the AOD in Paraguay and North Argentina derives from the Amazonia-Cerrado fires. Due to the presence of the inter-tropical convergence zone, which decouples wind circulation of the two hemispheres, regions north of the Equator (Venezuela, Guyana, Suriname) are found to receive
Wang, Xiaolong; Gao, Dawen
2016-11-01
The one-stage partial nitritation and anammox process (PN/A) has been a promising microbial process to remove ammonia from wastewater especially with low carbon/nitrogen ratio. The main breakdown was the deterioration caused by overgrowth of nitrite oxidizing bacteria (NOB) resulting effluent nitrate build-up in the PN/A process. This study presented an in-situ restoring strategy for suppressing NOB activity in a one-stage granular PN/A system deteriorated over 2 months, using elevated concentrations of substrates (ammonia and nitrite) under limited dissolved oxygen level. The results showed that the NOB activity was successfully suppressed after 56 days of restoration, and finally the ratio of produced nitrate/consumed ammonium was reduced from 36.8% to 7%. On day 66 the nitrogen removal rate obtained as 1.2 kg N/(m3·d). The high FA level (5–40 mg/L) and low dissolved oxygen (growth, and AOB stay stable, but Nitrospira increase and Nitrobacter declined. High amount of NOB was still persistent in the granules, which was not easy to wash-out and threaten the deammonification performance.
Directory of Open Access Journals (Sweden)
Jin Wang
2017-01-01
Full Text Available In this paper, three different fertilizer draw solutions were tested in a novel forward osmosis-microfiltration aerobic membrane bioreactor (MF-FDFO-MBR hybrid system and their performance were evaluated in terms of water flux and reverse salt diffusion. Results were also compared with a standard solution. Results showed that ammonium sulfate is the most suitable fertilizer for this hybrid system since it has a relatively high water flux (6.85 LMH with a comparatively low reverse salt flux (3.02 gMH. The performance of the process was also studied by investigating different process parameters: draw solution concentration, FO draw solution flow rate and MF imposed flux. It was found that the optimal conditions for this hybrid system were: draw solution concentration of 1 M, FO draw solution flow rate of 200 mL/min and MF imposed flux of 10 LMH. The salt accumulation increased from 834 to 5400 μS/cm during the first four weeks but after integrating MF, the salinity dropped significantly from 5400 to 1100 μS/cm suggesting that MF is efficient in mitigating the salinity build up inside the reactor. This study demonstrated that the integration of the MF membrane could effectively control the salinity and enhance the stable FO flux in the OMBR.
Arroll, Megan A; Howard, Alex
2013-01-01
The aim of this study was to explore the phenomenon of identity change and subsequent post-traumatic growth (PTG) in individuals with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Ten participants (average illness duration 7.4 years) were interviewed (average length, 79 minutes) via a semi-structured interview schedule and verbatim transcriptions were analysed with interpretative phenomenological analysis. The four superordinate themes revealed were 'comparisons of past to present self: "you have to be someone else, and you have to live with that''', 'the effect of social isolation on identity and subsequent insights into others' behaviours', 'contemplation of future and identity: ''where do I go from here?"', and 'PTG: "the letting go, the building up, [and] the gradual process of rebuilding"'. These themes outlined the experiences of those with ME/CFS as they underwent changes in identity due to the limitations the condition imposed on activities and roles, understanding others' behaviours after a period of isolation, the comparison of the past self with the present self and finally, the positive growth that was noted by two of the interviewees with regards to a new 'true' self. Despite the distressing and unpredictable nature of ME/CFS, it appears that individuals with this disorder can experience personal growth.
军队疗养院质量管理体系构建%Building up Quality Management System in Military Sanatoriums
Institute of Scientific and Technical Information of China (English)
祝宏; 郑守虎
2015-01-01
通过医疗质量组织体系、技术标准体系及信息系统建设、疗养路径管理、质量文化培育、重大阳性结果及危急值报告与处理制度的建立、合理用药与合理食疗干预机制的实施，多维度揭示疗养院质量管理体系构建在医疗质量控制中的主要作用。%By building up medical quality management system, technical standard system and information system, managing the ways of nursing, cultivating quality culture, establishing the reporting and processing system of significant positive results and urgencies, implementing the intervention of rational medician and food therapy, the major effect of quality management system on medical quality control in military sanatorium was revealed.
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Michael J Raupach
Full Text Available During the last few years, DNA barcoding has become an efficient method for the identification of species. In the case of insects, most published DNA barcoding studies focus on species of the Ephemeroptera, Trichoptera, Hymenoptera and especially Lepidoptera. In this study we test the efficiency of DNA barcoding for true bugs (Hemiptera: Heteroptera, an ecological and economical highly important as well as morphologically diverse insect taxon. As part of our study we analyzed DNA barcodes for 1742 specimens of 457 species, comprising 39 families of the Heteroptera. We found low nucleotide distances with a minimum pairwise K2P distance 2.2% were detected for 16 traditionally recognized and valid species. With a successful identification rate of 91.5% (418 species our study emphasizes the use of DNA barcodes for the identification of true bugs and represents an important step in building-up a comprehensive barcode library for true bugs in Germany and Central Europe as well. Our study also highlights the urgent necessity of taxonomic revisions for various taxa of the Heteroptera, with a special focus on various species of the Miridae. In this context we found evidence for on-going hybridization events within various taxonomically challenging genera (e.g. Nabis Latreille, 1802 (Nabidae, Lygus Hahn, 1833 (Miridae, Phytocoris Fallén, 1814 (Miridae as well as the putative existence of cryptic species (e.g. Aneurus avenius (Duffour, 1833 (Aradidae or Orius niger (Wolff, 1811 (Anthocoridae.
Efficient broadcast on random geometric graphs
Energy Technology Data Exchange (ETDEWEB)
Bradonjic, Milan [Los Alamos National Laboratory; Elsasser, Robert [UNIV OF PADERBORN; Friedrich, Tobias [INTERNATIONAL COMPUTER SCI.; Sauerwald, Thomas [INTERNATIONAL COMPUTER SCI.
2009-01-01
A Randon Geometric Graph (RGG) is constructed by distributing n nodes uniformly at random in the unit square and connecting two nodes if their Euclidean distance is at most r, for some prescribed r. They analyze the following randomized broadcast algorithm on RGGs. At the beginning, there is only one informed node. Then in each round, each informed node chooses a neighbor uniformly at random and informs it. They prove that this algorithm informs every node in the largest component of a RGG in {Omicron}({radical}n/r) rounds with high probability. This holds for any value of r larger than the critical value for the emergence of a giant component. In particular, the result implies that the diameter of the giant component is {Theta}({radical}n/r).
Implicit quasilinear differential systems: a geometrical approach
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Miguel C. Munoz-Lecanda
1999-04-01
Full Text Available This work is devoted to the study of systems of implicit quasilinear differential equations. In general, no set of initial conditions is admissible for the system. It is shown how to obtain a vector field whose integral curves are the solution of the system, thus reducing the system to one that is ordinary. Using geometrical techniques, we give an algorithmic procedure in order to solve these problems for systems of the form $A(xdot x =alpha (x$ with $A(x$ being a singular matrix. As particular cases, we recover some results of Hamiltonian and Lagrangian Mechanics. In addition, a detailed study of the symmetries of these systems is carried out. This algorithm is applied to several examples arising from technical applications related to control theory.
Salt bridges: geometrically specific, designable interactions.
Donald, Jason E; Kulp, Daniel W; DeGrado, William F
2011-03-01
Salt bridges occur frequently in proteins, providing conformational specificity and contributing to molecular recognition and catalysis. We present a comprehensive analysis of these interactions in protein structures by surveying a large database of protein structures. Salt bridges between Asp or Glu and His, Arg, or Lys display extremely well-defined geometric preferences. Several previously observed preferences are confirmed, and others that were previously unrecognized are discovered. Salt bridges are explored for their preferences for different separations in sequence and in space, geometric preferences within proteins and at protein-protein interfaces, co-operativity in networked salt bridges, inclusion within metal-binding sites, preference for acidic electrons, apparent conformational side chain entropy reduction on formation, and degree of burial. Salt bridges occur far more frequently between residues at close than distant sequence separations, but, at close distances, there remain strong preferences for salt bridges at specific separations. Specific types of complex salt bridges, involving three or more members, are also discovered. As we observe a strong relationship between the propensity to form a salt bridge and the placement of salt-bridging residues in protein sequences, we discuss the role that salt bridges might play in kinetically influencing protein folding and thermodynamically stabilizing the native conformation. We also develop a quantitative method to select appropriate crystal structure resolution and B-factor cutoffs. Detailed knowledge of these geometric and sequence dependences should aid de novo design and prediction algorithms.
Genetic Algorithms and Local Search
Whitley, Darrell
1996-01-01
The first part of this presentation is a tutorial level introduction to the principles of genetic search and models of simple genetic algorithms. The second half covers the combination of genetic algorithms with local search methods to produce hybrid genetic algorithms. Hybrid algorithms can be modeled within the existing theoretical framework developed for simple genetic algorithms. An application of a hybrid to geometric model matching is given. The hybrid algorithm yields results that improve on the current state-of-the-art for this problem.
de Casteljau's Algorithm Revisited
DEFF Research Database (Denmark)
Gravesen, Jens
1998-01-01
It is demonstrated how all the basic properties of Bezier curves can be derived swiftly and efficiently without any reference to the Bernstein polynomials and essentially with only geometric arguments. This is achieved by viewing one step in de Casteljau's algorithm as an operator (the de Casteljau...
Harmonic and geometric analysis
Citti, Giovanna; Pérez, Carlos; Sarti, Alessandro; Zhong, Xiao
2015-01-01
This book presents an expanded version of four series of lectures delivered by the authors at the CRM. Harmonic analysis, understood in a broad sense, has a very wide interplay with partial differential equations and in particular with the theory of quasiconformal mappings and its applications. Some areas in which real analysis has been extremely influential are PDE's and geometric analysis. Their foundations and subsequent developments made extensive use of the Calderón–Zygmund theory, especially the Lp inequalities for Calderón–Zygmund operators (Beurling transform and Riesz transform, among others) and the theory of Muckenhoupt weights. The first chapter is an application of harmonic analysis and the Heisenberg group to understanding human vision, while the second and third chapters cover some of the main topics on linear and multilinear harmonic analysis. The last serves as a comprehensive introduction to a deep result from De Giorgi, Moser and Nash on the regularity of elliptic partial differen...
Geometrical approach to fluid models
Kuvshinov, B. N.; Schep, T. J.
1997-01-01
Differential geometry based upon the Cartan calculus of differential forms is applied to investigate invariant properties of equations that describe the motion of continuous media. The main feature of this approach is that physical quantities are treated as geometrical objects. The geometrical
In Defence of Geometrical Algebra
Blasjo, V.N.E.
2016-01-01
The geometrical algebra hypothesis was once the received interpretation of Greek mathematics. In recent decades, however, it has become anathema to many. I give a critical review of all arguments against it and offer a consistent rebuttal case against the modern consensus. Consequently, I find that the geometrical algebra interpretation should be reinstated as a viable historical hypothesis.
Homological Type of Geometric Transitions
Rossi, Michele
2010-01-01
The present paper gives an account and quantifies the change in topology induced by small and type II geometric transitions, by introducing the notion of the \\emph{homological type} of a geometric transition. The obtained results agree with, and go further than, most results and estimates, given to date by several authors, both in mathematical and physical literature.
Geometrical approach to fluid models
Kuvshinov, B. N.; Schep, T. J.
1997-01-01
Differential geometry based upon the Cartan calculus of differential forms is applied to investigate invariant properties of equations that describe the motion of continuous media. The main feature of this approach is that physical quantities are treated as geometrical objects. The geometrical notio
Transmuted Complementary Weibull Geometric Distribution
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Ahmed Z. A fify
2014-12-01
Full Text Available This paper provides a new generalization of the complementary Weibull geometric distribution that introduced by Tojeiro et al. (2014, using the quadratic rank transmutation map studied by Shaw and Buckley (2007. The new distribution is referred to as transmuted complementary Weibull geometric distribution (TCWGD. The TCWG distribution includes as special cases the complementary Weibull geometric distribution (CWGD, complementary exponential geometric distribution(CEGD,Weibull distribution (WD and exponential distribution (ED. Various structural properties of the new distribution including moments, quantiles, moment generating function and RØnyi entropy of the subject distribution are derived. We proposed the method of maximum likelihood for estimating the model parameters and obtain the observed information matrix. A real data set are used to compare the exibility of the transmuted version versus the complementary Weibull geometric distribution.
Pose measurement method based on geometrical constraints
Institute of Scientific and Technical Information of China (English)
Zimiao Zhang; Changku Sun; Pengfei Sun; Peng Wang
2011-01-01
@@ The pose estimation method based on geometric constraints is studied.The coordinates of the five feature points in the camera coordinate system are calculated to obtain the pose of an object on the basis of the geometric constraints formed by the connective lines of the feature points and the coordinates of the feature points on the CCD image plane; during the solution process,the scaling and orthography projection model is used to approximate the perspective projection model.%The pose estimation method based on geometric constraints is studied. The coordinates of the five feature points in the camera coordinate system are calculated to obtain the pose of an object on the basis of the geometric constraints formed by the connective lines of the feature points and the coordinates of the feature points on the CCD image plane; during the solution process, the scaling and orthography projection model is used to approximate the perspective projection model. The initial values of the coordinates of the five feature points in the camera coordinate system are obtained to ensure the accuracy and convergence rate of the non-linear algorithm. In accordance with the perspective projection characteristics of the circular feature landmarks, we propose an approach that enables the iterative acquisition of accurate target poses through the correction of the perspective projection coordinates of the circular feature landmark centers. Experimental results show that the translation positioning accuracy reaches ±0.05 mm in the measurement range of 0-40 mm, and the rotation positioning accuracy reaches ±0.06° in the measurement range of 4°-60°.
Integrating geometric activity images in ANN classification
De Genst, William; Gautama, Sidharta; Bellens, Rik; Canters, Frank
2005-10-01
In this paper we demonstrate how the interaction between innovative methods in the field of computer vision and methods for multi-spectral image classification can help in extracting detailed land-cover / land-use information from Very High Resolution (VHR) satellite imagery. We introduce the novel concept of "geometric activity images", which we define as images encoding the strength of the relationship between a pixel and surrounding features detected through dedicated computer vision methods. These geometric activity images are used as alternatives to more traditional texture images that better describe the geometry of man-made structures and that can be included as additional information in a non-parametric supervised classification framework. We present a number of findings resulting from the integration of geometric activity images and multi-spectral bands in an artificial neural network classification. The geometric activity images we use result from the use of a ridge detector for straight line detection, calculated for different window sizes and for all multi-spectral bands and band-ratio images in a VHR scene. A selection of the most relevant bands to use for classification is carried out using band selection based on a genetic algorithm. Sensitivity analysis is used to assess the importance of each input variable. An application of the proposed methods to part of a Quickbird image taken over the suburban fringe of the city of Ghent (Belgium) shows that we are able to identify roads with much higher accuracy than when using more traditional multi-spectral image classification techniques.
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Xavier Le Roux
Full Text Available Random reductions in plant diversity can affect ecosystem functioning, but it is still unclear which components of plant diversity (species number - namely richness, presence of particular plant functional groups, or particular combinations of these and associated biotic and abiotic drivers explain the observed relationships, particularly for soil processes. We assembled grassland communities including 1 to 16 plant species with a factorial separation of the effects of richness and functional group composition to analyze how plant diversity components influence soil nitrifying and denitrifying enzyme activities (NEA and DEA, respectively, the abundance of nitrifiers (bacterial and archaeal amoA gene number and denitrifiers (nirK, nirS and nosZ gene number, and key soil environmental conditions. Plant diversity effects were largely due to differences in functional group composition between communities of identical richness (number of sown species, though richness also had an effect per se. NEA was positively related to the percentage of legumes in terms of sown species number, the additional effect of richness at any given legume percentage being negative. DEA was higher in plots with legumes, decreased with increasing percentage of grasses, and increased with richness. No correlation was observed between DEA and denitrifier abundance. NEA increased with the abundance of ammonia oxidizing bacteria. The effect of richness on NEA was entirely due to the build-up of nitrifying organisms, while legume effect was partly linked to modified ammonium availability and nitrifier abundance. Richness effect on DEA was entirely due to changes in soil moisture, while the effects of legumes and grasses were partly due to modified nitrate availability, which influenced the specific activity of denitrifiers. These results suggest that plant diversity-induced changes in microbial specific activity are important for facultative activities such as denitrification
Directory of Open Access Journals (Sweden)
Keiichi YOSHIDA
2014-01-01
Full Text Available Objective: The purpose of this study was to evaluate the Knoop hardness number (KHN of dual-cured core build-up resin composites (DCBRCs at 6 depths of cavity after 3 post-irradiation times by 4 light-exposure methods. Material and Methods: Five specimens each of DCBRCs (Clearfil DC Core Plus [DCP] and Unifil Core EM [UCE] were filled in acrylic resin blocks with a semi-cylindrical cavity and light-cured using an LED light unit (power density: 1,000 mW/cm2at the top surface by irradiation for 20 seconds (20 s, 40 seconds (40 s, bonding agent plus 20 seconds (B+20 s, or 40 seconds plus light irradiation of both sides of each acrylic resin block for 40 seconds each (120 s. KHN was measured at depths of 0.5, 2.0, 4.0, 6.0, 8.0, and 10.0 mm at 0.5 hours, 24 hours, and 7 days post-irradiation. Statistical analysis was performed using repeated measures ANOVA and Tukey's compromise post-hoc test with a significance level of p0.05. In DCP, and not UCE, at 24 hours and 7 days post-irradiation, the B+20 s method showed significantly higher KHN at all depths of cavity, except the depth of 0.5 mm (p<0.05. Conclusion: KHN depends on the light-exposure method, use of bonding agent, depth of cavity, post-irradiation time, and material brand. Based on the microhardness behavior, DCBRCs are preferably prepared by the effective exposure method, when used for a greater depth of cavity.
Peters, Achim; Langemann, Dirk
2009-01-01
Obesity and type 2 diabetes have become the major health problems in many industrialized countries. A few theoretical frameworks have been set up to derive the possible determinative cause of obesity. One concept views that food availability determines food intake, i.e. that obesity is the result of an external energy "push" into the body. Another one views that the energy milieu within the human organism determines food intake, i.e. that obesity is due to an excessive "pull" from inside the organism. Here we present the unconventional concept that a healthy organism is maintained by a "competent brain-pull" which serves systemic homeostasis, and that the underlying cause of obesity is "incompetent brain-pull", i.e. that the brain is unable to properly demand glucose from the body. We describe the energy fluxes from the environment, through the body, towards the brain with a mathematical "supply chain" model and test whether its predictions fit medical and experimental data sets from our and other research groups. In this way, we show data-based support of our hypothesis, which states that under conditions of food abundance incompetent brain-pull will lead to build-ups in the supply chain culminating in obesity and type 2 diabetes. In the same way, we demonstrate support of the related hypothesis, which states that under conditions of food deprivation a competent brain-pull mechanism is indispensable for the continuance of the brain s high energy level. In conclusion, we took the viewpoint of integrative physiology and provided evidence for the necessity of brain-pull mechanisms for the benefit of health. Along these lines, our work supports recent molecular findings from the field of neuroenergetics and continues the work on the "Selfish Brain" theory dealing with the maintenance of the cerebral and peripheral energy homeostasis.
Directory of Open Access Journals (Sweden)
Achim Peters
2009-04-01
Full Text Available Obesity and type 2 diabetes have become the major health problems in many industrialized countries. A few theoretical frameworks have been set up to derive the possible determinative cause of obesity. One concept views that food availability determines food intake, i.e. that obesity is the result of an external energy “push” into the body. Another one views that the energy milieu within the human organism determines food intake, i.e. that obesity is due to an excessive “pull” from inside the organism. Here we present the unconventional concept that a healthy organism is maintained by a „competent brain-pull“ which serves systemic homeostasis, and that the underlying cause of obesity is “incompetent brain-pull”, i.e. that the brain is unable to properly demand glucose from the body. We describe the energy fluxes from the environment, through the body, towards the brain with a mathematical “supply chain” model and test whether its predictions fit medical and experimental data sets from our and other research groups. In this way, we show data-based support of our hypothesis, which states that under conditions of food abundance incompetent brain-pull will lead to build-ups in the supply chain culminating in obesity and type 2 diabetes. In the same way, we demonstrate support of the related hypothesis, which states that under conditions of food deprivation a competent brain-pull mechanism is indispensable for the continuance of the brain´s high energy level. In conclusion, we took the viewpoint of integrative physiology and provided evidence for the necessity of brain-pull mechanisms for the benefit of health. Along these lines, our work supports recent molecular findings from the field of neuroenergetics and continues the work on the “Selfish Brain” theory dealing with the maintenance of the cerebral and peripheral energy homeostasis.
D'Haese, Arnout; Le-Clech, Pierre; Van Nevel, Sam; Verbeken, Kim; Cornelissen, Emile R; Khan, Stuart J; Verliefde, Arne R D
2013-09-15
In this study, trace organics transport in closed-loop forward osmosis (FO) systems was assessed. The FO systems considered, consisted of an FO unit and a nanofiltration (NF) or reverse osmosis (RO) unit, with the draw solution circulating between both units. The rejection of trace organics by FO, NF and RO was tested. It was found that the rejection rates of FO were generally comparable with NF and lower than RO rejection rates. To assess the influence of fouling in FO on trace organics rejection, FO membranes were fouled with sodium alginate, bovine serum albumin or by biofilm growth, after which trace organics rejection was tested. A negative influence of fouling on FO rejection was found which was limited in most cases, while it was significant for some compounds such as paracetamol and naproxen, indicating specific compound-foulant interactions. The transport mechanism of trace organics in FO was tested, in order to differentiate between diffusive and convective transport. The concentration of trace organics in the final product water and the build-up of trace organics in the draw solution were modeled assuming the draw solution was reconcentrated by NF/RO and taking into account different transport mechanisms for the FO membrane and different rejection rates by NF/RO. Modeling results showed that if the FO rejection rate is lower than the RO rejection rate (as is the case for most compounds tested), the added value of the FO-RO cycle compared to RO only at steady-state was small for diffusively and negative for convectively transported trace organics. Modeling also showed that trace organics accumulate in the draw solution.
Directory of Open Access Journals (Sweden)
J. Meyer
2015-07-01
Full Text Available Ocean deoxygenation due to climate change may alter redox-sensitive nutrient cycles in the marine environment. The productive eastern tropical North Atlantic (ETNA upwelling region may be particularly affected when the relatively moderate oxygen minimum zone (OMZ deoxygenates further and microbially-driven nitrogen (N loss processes are promoted. Consequently, water masses with a low N : P ratio could reach the euphotic layer, possibly influencing primary production in those waters. Previous mesocosm studies in the oligotrophic Atlantic Ocean identified N availability as controlling of primary production, while a possible co-limitation of nitrate and phosphate (P could not be ruled out. To better understand the impact of changing N : P ratios on primary production and on N2 fixation in the ETNA surface ocean, we conducted land-based mesocosm experiments with natural plankton communities and applied a broad range of N : P ratios (2.67–48. Silicate was supplied at 15 μmol L−1 in all mesocosms. We monitored nutrient drawdown, bloom formation, biomass build up and diazotrophic feedback in response to variable nutrient stoichiometry. Our results confirmed N to be limiting to primary production. We found that excess P was channeled through particulate organic matter (POP into the dissolved organic matter (DOP pool. In mesocosms with low P availability, DOP was utilized while N2 fixation increased, suggesting a link between those two processes. Interestingly this observation was most pronounced in mesocosms where inorganic N was still available, indicating that bioavailable N does not necessarily has to have a negative impact on N2 fixation. We observed a shift from a mixed cyanobacterial/proteobacterial dominated active diazotrophic community towards diazotrophic diatom symbionts of the Richelia-Rhizosolenia symbiosis. We hypothesize that a potential change in nutrient stoichiometry in the ETNA might lead to a general shift within the
Cotes, Caroline; Cardoso, Mayra; Melo, Renata Marques de; Valandro, Luiz Felipe; Bottino, Marco Antonio
2015-01-01
The purpose of this study was to assess the influence of conditioning methods and thermocycling on the bond strength between composite core and resin cement. Eighty blocks (8×8×4 mm) were prepared with core build-up composite. The cementation surface was roughened with 120-grit carbide paper and the blocks were thermocycled (5,000 cycles, between 5°C and 55°C, with a 30 s dwell time in each bath). A layer of temporary luting agent was applied. After 24 h, the layer was removed, and the blocks were divided into five groups, according to surface treatment: (NT) No treatment (control); (SP) Grinding with 120-grit carbide paper; (AC) Etching with 37% phosphoric acid; (SC) Sandblasting with 30 mm SiO2 particles, silane application; (AO) Sandblasting with 50 mm Al2O3 particles, silane application. Two composite blocks were cemented to each other (n=8) and sectioned into sticks. Half of the specimens from each block were immediately tested for microtensile bond strength (µTBS), while the other half was subjected to storage for 6 months, thermocycling (12,000 cycles, between 5°C and 55°C, with a dwell time of 30 s in each bath) and µTBS test in a mechanical testing machine. Bond strength data were analyzed by repeated measures two-way ANOVA and Tukey test (α=0.05). The µTBS was significantly affected by surface treatment (p=0.007) and thermocycling (p=0.000). Before aging, the SP group presented higher bond strength when compared to NT and AC groups, whereas all the other groups were statistically similar. After aging, all the groups were statistically similar. SP submitted to thermocycling showed lower bond strength than SP without thermocycling. Core composites should be roughened with a diamond bur before the luting process. Thermocycling tends to reduce the bond strength between composite and resin cement.
Patton, Henry; Hubbard, Alun; Andreassen, Karin; Winsborrow, Monica; Stroeven, Arjen P.
2016-12-01
The Eurasian ice-sheet complex (EISC) was the third largest ice mass during the Last Glacial Maximum (LGM), after the Antarctic and North American ice sheets. Despite its global significance, a comprehensive account of its evolution from independent nucleation centres to its maximum extent is conspicuously lacking. Here, a first-order, thermomechanical model, robustly constrained by empirical evidence, is used to investigate the dynamics of the EISC throughout its build-up to its maximum configuration. The ice flow model is coupled to a reference climate and applied at 10 km spatial resolution across a domain that includes the three main spreading centres of the Celtic, Fennoscandian and Barents Sea ice sheets. The model is forced with the NGRIP palaeo-isotope curve from 37 ka BP onwards and model skill is assessed against collated flowsets, marginal moraines, exposure ages and relative sea-level history. The evolution of the EISC to its LGM configuration was complex and asynchronous; the western, maritime margins of the Fennoscandian and Celtic ice sheets responded rapidly and advanced across their continental shelves by 29 ka BP, yet the maximum aerial extent (5.48 × 106 km2) and volume (7.18 × 106 km3) of the ice complex was attained some 6 ka later at c. 22.7 ka BP. This maximum stand was short-lived as the North Sea and Atlantic margins were already in retreat whilst eastern margins were still advancing up until c. 20 ka BP. High rates of basal erosion are modelled beneath ice streams and outlet glaciers draining the Celtic and Fennoscandian ice sheets with extensive preservation elsewhere due to frozen subglacial conditions, including much of the Barents and Kara seas. Here, and elsewhere across the Norwegian shelf and North Sea, high pressure subglacial conditions would have promoted localised gas hydrate formation.
Institute of Scientific and Technical Information of China (English)
文颖; 曾庆元
2013-01-01
几何刚度矩阵的推演是结构几何非线性有限元分析的重点和难点之一。推导几何刚度矩阵显式解析表达式成为简化非线性有限元列式，提高分析效率的关键。本文在协同转动法框架下，基于刚体运动法则对四节点二十四自由度的平板壳单元几何刚度矩阵显式解析式进行了推导和讨论；分析了悬臂梁大转动、不同壁厚条件下简支圆柱形屋顶空间大变位两个经典算例。研究结果表明：（1）几何刚度矩阵的显式计算公式不仅为板壳结构几何非线性列式提供了方便而且具有良好的精度；（2）推导的几何刚度矩阵适用于各类型四边形二十四自由度平板壳单元模型；（3）与数值积分相比，采用解析形式的几何刚度矩阵可以显著提高非线性响应计算效率。%The derivation of geometric stiffness matrix is an essential and difficult stage in conducting the finite element analysis of geometrically nonlinear structural problems .Any attempt to obtaining explicit-ly the analytical expression of geometric stiffness matrix is of great importance for simplifying the for-mulation ,and in particular for improving efficiency and effectiveness of the overall procedure .In the con-text of co-rotational formulation ,an algorithm analytically leading to the geometric stiffness matrix of the 4-node quadrilateral flat shell element with a total of 24 degrees of freedom was presented based on the rigid body motion rule and consecutively subject to discussion .Two benchmark problems ,namely the large rotation problem of a cantilever beam and the large deflection behaviour of a hinged semi-cylindrical roof with two typical thicknesses subjected to a central pinching force ,were analyzed for demonstrating the reliability and robustness of the proposed procedure .The results of numerical study reveal that :(1) The explicit formula derived herein provides a great deal of convenience while
A differential-geometric approach to generalized linear models with grouped predictors
Augugliaro, Luigi; Mineo, Angelo M.; Wit, Ernst C.
2016-01-01
We propose an extension of the differential-geometric least angle regression method to perform sparse group inference in a generalized linear model. An efficient algorithm is proposed to compute the solution curve. The proposed group differential-geometric least angle regression method has important
Fifth SIAM conference on geometric design 97: Final program and abstracts. Final technical report
Energy Technology Data Exchange (ETDEWEB)
NONE
1997-12-31
The meeting was divided into the following sessions: (1) CAD/CAM; (2) Curve/Surface Design; (3) Geometric Algorithms; (4) Multiresolution Methods; (5) Robotics; (6) Solid Modeling; and (7) Visualization. This report contains the abstracts of papers presented at the meeting. Proceding the conference there was a short course entitled ``Wavelets for Geometric Modeling and Computer Graphics``.
Multiple structural alignment and core detection by geometric hashing.
Leibowitz, N; Fligelman, Z Y; Nussinov, R; Wolfson, H J
1999-01-01
A Multiple Structural Alignment algorithm is presented. The algorithm accepts an ensemble of protein structures and finds the largest substructure (core) of C alpha atoms whose geometric configuration appear in all the molecules of the ensemble (core). Both the detection of this core and the resulting structural alignment are done simultaneously. Other large enough multistructural superimpositions are detected as well. Our method is based on the Geometric Hashing paradigm and a superimposition clustering technique which represents superimpositions by sets of matching atoms. The algorithm proved to be efficient on real data in a series of experiments. The same method can be applied to any ensemble of molecules (not necessarily proteins) since our basic technique is sequence order independent.
Geometric Computing for Freeform Architecture
Wallner, J.
2011-06-03
Geometric computing has recently found a new field of applications, namely the various geometric problems which lie at the heart of rationalization and construction-aware design processes of freeform architecture. We report on our work in this area, dealing with meshes with planar faces and meshes which allow multilayer constructions (which is related to discrete surfaces and their curvatures), triangles meshes with circle-packing properties (which is related to conformal uniformization), and with the paneling problem. We emphasize the combination of numerical optimization and geometric knowledge.
Geometric inequalities for black holes
Energy Technology Data Exchange (ETDEWEB)
Dain, Sergio [Universidad Nacional de Cordoba (Argentina)
2013-07-01
Full text: A geometric inequality in General Relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities, which are valid in the dynamical and strong field regime, play an important role in the characterization of the gravitational collapse. They are closed related with the cosmic censorship conjecture. In this talk I will review recent results in this subject. (author)
Paelinck, L; De Wagter, C; Van Esch, A; Duthoy, W; Depuydt, T; De Neve, W
2005-02-07
Skin toxicity has been reported for IMRT of head and neck cancer. The purpose of this study was to investigate the dose in the build-up region delivered by a 6 MV treatment plan for which important skin toxicity was observed. We also investigated if the different designs of the treatment head of an Elekta and a Varian linear accelerator, especially the lower position of the Varian multi-leaf collimator, give rise to different build-up doses. For regular square open beams, the build-up dose along the central beam axis is higher for the Varian machine than for the Elekta machine, both for 6 MV and 18 MV. At the Elekta machine at 18 MV, the superficial dose of a diamond shaped 10 x 10 cm2 field is 3.6% lower than the superficial dose of a regular 10 x 10 cm2 field. This effect is not seen at 6 MV. At the Varian machine, the superficial dose of the diamond shaped field is respectively 3.5 and 14.2% higher than the superficial dose of the regular 10 x 10 cm2 field for 6 MV and 18 MV. Despite the differences measured in build-up dose for single beams between the Elekta and the Varian linear accelerator, there were no measurable differences in superficial dose when a typical IMRT dose plan of 6 MV for a head and neck tumour is executed at the two machines.
Mobile Watermarking against Geometrical Distortions
Directory of Open Access Journals (Sweden)
Jing Zhang
2015-08-01
Full Text Available Mobile watermarking robust to geometrical distortions is still a great challenge. In mobile watermarking, efficient computation is necessary because mobile devices have very limited resources due to power consumption. In this paper, we propose a low-complexity geometrically resilient watermarking approach based on the optimal tradeoff circular harmonic function (OTCHF correlation filter and the minimum average correlation energy Mellin radial harmonic (MACE-MRH correlation filter. By the rotation, translation and scale tolerance properties of the two kinds of filter, the proposed watermark detector can be robust to geometrical attacks. The embedded watermark is weighted by a perceptual mask which matches very well with the properties of the human visual system. Before correlation, a whitening process is utilized to improve watermark detection reliability. Experimental results demonstrate that the proposed watermarking approach is computationally efficient and robust to geometrical distortions.
Geometric structure of gauge theories
Energy Technology Data Exchange (ETDEWEB)
Mangiarotti, L.; Modugno, M.
1985-06-01
In the framework of the adjoint forms over the jet spaces of connections and using a canonical jet shift differential, we give a geometrical interpretation of the Yang--Mills equations both in a direct and Lagrangian formulation.
Geometric integrator for simulations in the canonical ensemble
Tapias, Diego; Sanders, David P.; Bravetti, Alessandro
2016-08-01
We introduce a geometric integrator for molecular dynamics simulations of physical systems in the canonical ensemble that preserves the invariant distribution in equations arising from the density dynamics algorithm, with any possible type of thermostat. Our integrator thus constitutes a unified framework that allows the study and comparison of different thermostats and of their influence on the equilibrium and non-equilibrium (thermo-)dynamic properties of a system. To show the validity and the generality of the integrator, we implement it with a second-order, time-reversible method and apply it to the simulation of a Lennard-Jones system with three different thermostats, obtaining good conservation of the geometrical properties and recovering the expected thermodynamic results. Moreover, to show the advantage of our geometric integrator over a non-geometric one, we compare the results with those obtained by using the non-geometric Gear integrator, which is frequently used to perform simulations in the canonical ensemble. The non-geometric integrator induces a drift in the invariant quantity, while our integrator has no such drift, thus ensuring that the system is effectively sampling the correct ensemble.
Geometric integrator for simulations in the canonical ensemble.
Tapias, Diego; Sanders, David P; Bravetti, Alessandro
2016-08-28
We introduce a geometric integrator for molecular dynamics simulations of physical systems in the canonical ensemble that preserves the invariant distribution in equations arising from the density dynamics algorithm, with any possible type of thermostat. Our integrator thus constitutes a unified framework that allows the study and comparison of different thermostats and of their influence on the equilibrium and non-equilibrium (thermo-)dynamic properties of a system. To show the validity and the generality of the integrator, we implement it with a second-order, time-reversible method and apply it to the simulation of a Lennard-Jones system with three different thermostats, obtaining good conservation of the geometrical properties and recovering the expected thermodynamic results. Moreover, to show the advantage of our geometric integrator over a non-geometric one, we compare the results with those obtained by using the non-geometric Gear integrator, which is frequently used to perform simulations in the canonical ensemble. The non-geometric integrator induces a drift in the invariant quantity, while our integrator has no such drift, thus ensuring that the system is effectively sampling the correct ensemble.
Geometric phases in graphitic cones
Energy Technology Data Exchange (ETDEWEB)
Furtado, Claudio [Departamento de Fisica, CCEN, Universidade Federal da Paraiba, Cidade Universitaria, 58051-970 Joao Pessoa, PB (Brazil)], E-mail: furtado@fisica.ufpb.br; Moraes, Fernando [Departamento de Fisica, CCEN, Universidade Federal da Paraiba, Cidade Universitaria, 58051-970 Joao Pessoa, PB (Brazil); Carvalho, A.M. de M [Departamento de Fisica, Universidade Estadual de Feira de Santana, BR116-Norte, Km 3, 44031-460 Feira de Santana, BA (Brazil)
2008-08-04
In this Letter we use a geometric approach to study geometric phases in graphitic cones. The spinor that describes the low energy states near the Fermi energy acquires a phase when transported around the apex of the cone, as found by a holonomy transformation. This topological result can be viewed as an analogue of the Aharonov-Bohm effect. The topological analysis is extended to a system with n cones, whose resulting configuration is described by an effective defect00.
Determining Geometric Accuracy in Turning
Institute of Scientific and Technical Information of China (English)
Kwong; Chi; Kit; A; Geddam
2002-01-01
Mechanical components machined to high levels of ac cu racy are vital to achieve various functional requirements in engineering product s. In particular, the geometric accuracy of turned components play an important role in determining the form, fit and function of mechanical assembly requiremen ts. The geometric accuracy requirements of turned components are usually specifi ed in terms of roundness, straightness, cylindricity and concentricity. In pract ice, the accuracy specifications achievable are infl...
The Geometric Gravitational Internal Problem
González-Martin, G R
2000-01-01
In a geometric unified theory there is an energy momentum equation, apart from the field equations and equations of motion. The general relativity Einstein equation with cosmological constant follows from this energy momentum equation for empty space. For non empty space we obtain a generalized Einstein equation, relating the Einstein tensor to a geometric stress energy tensor. The matching exterior solution is in agreement with the standard relativity tests. Furthermore, there is a Newtonian limit where we obtain Poisson's equation.
Geometric symmetries in light nuclei
Bijker, Roelof
2016-01-01
The algebraic cluster model is is applied to study cluster states in the nuclei 12C and 16O. The observed level sequences can be understood in terms of the underlying discrete symmetry that characterizes the geometrical configuration of the alpha-particles, i.e. an equilateral triangle for 12C, and a regular tetrahedron for 16O. The structure of rotational bands provides a fingerprint of the underlying geometrical configuration of alpha-particles.
Geometric inequalities methods of proving
Sedrakyan, Hayk
2017-01-01
This unique collection of new and classical problems provides full coverage of geometric inequalities. Many of the 1,000 exercises are presented with detailed author-prepared-solutions, developing creativity and an arsenal of new approaches for solving mathematical problems. This book can serve teachers, high-school students, and mathematical competitors. It may also be used as supplemental reading, providing readers with new and classical methods for proving geometric inequalities. .
Weakly Nonlinear Geometric Optics for Hyperbolic Systems of Conservation Laws
Chen, Gui-Qiang; Zhang, Yongqian
2012-01-01
We establish an $L^1$-estimate to validate the weakly nonlinear geometric optics for entropy solutions of nonlinear hyperbolic systems of conservation laws with arbitrary initial data of small bounded variation. This implies that the simpler geometric optics expansion function can be employed to study the properties of general entropy solutions to hyperbolic systems of conservation laws. Our analysis involves new techniques which rely on the structure of the approximate equations, besides the properties of the wave-front tracking algorithm and the standard semigroup estimates.
Antenna with Dielectric Having Geometric Patterns
Dudley, Kenneth L. (Inventor); Elliott, Holly A. (Inventor); Cravey, Robin L. (Inventor); Connell, John W. (Inventor); Ghose, Sayata (Inventor); Watson, Kent A. (Inventor); Smith, Jr., Joseph G. (Inventor)
2013-01-01
An antenna includes a ground plane, a dielectric disposed on the ground plane, and an electrically-conductive radiator disposed on the dielectric. The dielectric includes at least one layer of a first dielectric material and a second dielectric material that collectively define a dielectric geometric pattern, which may comprise a fractal geometry. The radiator defines a radiator geometric pattern, and the dielectric geometric pattern is geometrically identical, or substantially geometrically identical, to the radiator geometric pattern.
Recursive estimation of the conditional geometric median in Hilbert spaces
Cardot, Hervé; Zitt, Pierre-André
2012-01-01
A recursive estimator of the conditional geometric median in Hilbert spaces is studied. It is based on a stochastic gradient algorithm whose aim is to minimize a weighted L1 criterion and is consequently well adapted for robust online estimation. The weights are controlled by a kernel function and an associated bandwidth. Almost sure convergence and L2 rates of convergence are proved under general conditions on the conditional distribution as well as the sequence of descent steps of the algorithm and the sequence of bandwidths. Asymptotic normality is also proved for the averaged version of the algorithm with an optimal rate of convergence. A simulation study confirms the interest of this new and fast algorithm when the sample sizes are large. Finally, the ability of these recursive algorithms to deal with very high-dimensional data is illustrated on the robust estimation of television audience profiles conditional on the total time spent watching television over a period of 24 hours.
Triangular Geometrized Sampling Heuristics for Fast Optimal Motion Planning
Directory of Open Access Journals (Sweden)
Ahmed Hussain Qureshi
2015-02-01
Full Text Available Rapidly-exploring Random Tree (RRT-based algorithms have become increasingly popular due to their lower computational complexity as compared with other path planning algorithms. The recently presented RRT* motion planning algorithm improves upon the original RRT algorithm by providing optimal path solutions. While RRT determines an initial collision-free path fairly quickly, RRT* guarantees almost certain convergence to an optimal, obstacle-free path from the start to the goal points for any given geometrical environment. However, the main limitations of RRT* include its slow processing rate and high memory consumption, due to the large number of iterations required for calculating the optimal path. In order to overcome these limitations, we present another improvement, i.e, the Triangular Geometerized-RRT* (TGRRT* algorithm, which utilizes triangular geometrical methods to improve the performance of the RRT* algorithm in terms of the processing time and a decreased number of iterations required for an optimal path solution. Simulations comparing the performance results of the improved TG-RRT* with RRT* are presented to demonstrate the overall improvement in performance and optimal path detection.
Triangular Geometrized Sampling Heuristics for Fast Optimal Motion Planning
Directory of Open Access Journals (Sweden)
Ahmed Hussain Qureshi
2015-02-01
Full Text Available Rapidly-exploring Random Tree (RRT-based algorithms have become increasingly popular due to their lower computational complexity as compared with other path planning algorithms. The recently presented RRT* motion planning algorithm improves upon the original RRT algorithm by providing optimal path solutions. While RRT determines an initial collision-free path fairly quickly, RRT* guarantees almost certain convergence to an optimal, obstacle-free path from the start to the goal points for any given geometrical environment. However, the main limitations of RRT* include its slow processing rate and high memory consumption, due to the large number of iterations required for calculating the optimal path. In order to overcome these limitations, we present another improvement, i.e, the Triangular Geometerized-RRT* (TG-RRT* algorithm, which utilizes triangular geometrical methods to improve the performance of the RRT* algorithm in terms of the processing time and a decreased number of iterations required for an optimal path solution. Simulations comparing the performance results of the improved TG-RRT* with RRT* are presented to demonstrate the overall improvement in performance and optimal path detection.
Gray, James; He, Yang-Hui; Jejjala, Vishnu; Mekareeya, Noppadol
2008-01-01
We take new algebraic and geometric perspectives on the old subject of SQCD. We count chiral gauge invariant operators using generating functions, or Hilbert series, derived from the plethystic programme and the Molien-Weyl formula. Using the character expansion technique, we also see how the global symmetries are encoded in the generating functions. Equipped with these methods and techniques of algorithmic algebraic geometry, we obtain the character expansions for theories with arbitrary numbers of colours and flavours. Moreover, computational algebraic geometry allows us to systematically study the classical vacuum moduli space of SQCD and investigate such structures as its irreducible components, degree and syzygies. We find the vacuum manifolds of SQCD to be affine Calabi-Yau cones over weighted projective varieties.
Geometric Properties of Grassmannian Frames for and
Directory of Open Access Journals (Sweden)
Benedetto John J
2006-01-01
Full Text Available Grassmannian frames are frames satisfying a min-max correlation criterion. We translate a geometrically intuitive approach for two- and three-dimensional Euclidean space ( and into a new analytic method which is used to classify many Grassmannian frames in this setting. The method and associated algorithm decrease the maximum frame correlation, and hence give rise to the construction of specific examples of Grassmannian frames. Many of the results are known by other techniques, and even more generally, so that this paper can be viewed as tutorial. However, our analytic method is presented with the goal of developing it to address unresovled problems in -dimensional Hilbert spaces which serve as a setting for spherical codes, erasure channel modeling, and other aspects of communications theory.
Random broadcast on random geometric graphs
Energy Technology Data Exchange (ETDEWEB)
Bradonjic, Milan [Los Alamos National Laboratory; Elsasser, Robert [UNIV OF PADERBORN; Friedrich, Tobias [ICSI/BERKELEY; Sauerwald, Tomas [ICSI/BERKELEY
2009-01-01
In this work, we consider the random broadcast time on random geometric graphs (RGGs). The classic random broadcast model, also known as push algorithm, is defined as: starting with one informed node, in each succeeding round every informed node chooses one of its neighbors uniformly at random and informs it. We consider the random broadcast time on RGGs, when with high probability: (i) RGG is connected, (ii) when there exists the giant component in RGG. We show that the random broadcast time is bounded by {Omicron}({radical} n + diam(component)), where diam(component) is a diameter of the entire graph, or the giant component, for the regimes (i), or (ii), respectively. In other words, for both regimes, we derive the broadcast time to be {Theta}(diam(G)), which is asymptotically optimal.
Geometrically Invariant Watermarking Scheme Based on Local Feature Points
Directory of Open Access Journals (Sweden)
Jing Li
2012-06-01
Full Text Available Based on local invariant feature points and cross ratio principle, this paper presents a feature-point-based image watermarking scheme. It is robust to geometric attacks and some signal processes. It extracts local invariant feature points from the image using the improved scale invariant feature transform algorithm. Utilizing these points as vertexes it constructs some quadrilaterals to be as local feature regions. Watermark is inserted these local feature regions repeatedly. In order to get stable local regions it adjusts the number and distribution of extracted feature points. In every chosen local feature region it decides locations to embed watermark bits based on the cross ratio of four collinear points, the cross ratio is invariant to projective transformation. Watermark bits are embedded by quantization modulation, in which the quantization step value is computed with the given PSNR. Experimental results show that the proposed method can strongly fight more geometrical attacks and the compound attacks of geometrical ones.
Energy Technology Data Exchange (ETDEWEB)
Comte, Annabelle; Farin, Sebastien [Andra, Chatenay-Malabry (France)
2015-07-01
2013 has been a banner year for Andra with widespread discussions on the question of long-term management of radioactive waste: a nationwide public discussion about the planned Cigeo deep disposal facility has been organized and national discussions on the energy source transition had inevitably brought up the question of what to do with future radioactive waste to be produced under the various scenarios put forward. In spite of an open institutional framework, with numerous legal provisions for citizen participation, 2013 showed that creation of a radioactive waste disposal facility is not, and cannot be, a question dealt with like breaking news, within a given temporal or spatial perimeter. Any attempts to bring up the subject under the spotlight of public scrutiny inevitably shift the discussions away from their central theme and abandon the underlying question - what should be done with the existing radioactive waste and the waste that is bound to be produced? - to move on to the other major question: ''Should we stop using nuclear power or not?'', which takes us away from our responsibilities towards future generations. Daring to face the question, anchor it in citizen discussions, and create awareness of our duties towards coming generations: this is the challenge that Andra had already set itself several years ago. Our position is a strong one; rather than seeking to mask the problem of radioactive waste, we must face up to our responsibilities: the waste is already there, and we have to do something with it. It will take time to be successful here. Long-term management of radioactive waste is clearly a really long-term matter. All the experience in the field has shown that it involves patience and careful listening, and requires building up a basis for solid trust among the potential neighboring population, who are the most directly concerned. Durable proximity human investment is one of the key factors of success. For over 20 years now
Multiscale geometric modeling of macromolecules I: Cartesian representation.
Xia, Kelin; Feng, Xin; Chen, Zhan; Tong, Yiying; Wei, Guo Wei
2014-01-01
This paper focuses on the geometric modeling and computational algorithm development of biomolecular structures from two data sources: Protein Data Bank (PDB) and Electron Microscopy Data Bank (EMDB) in the Eulerian (or Cartesian) representation. Molecular surface (MS) contains non-smooth geometric singularities, such as cusps, tips and self-intersecting facets, which often lead to computational instabilities in molecular simulations, and violate the physical principle of surface free energy minimization. Variational multiscale surface definitions are proposed based on geometric flows and solvation analysis of biomolecular systems. Our approach leads to geometric and potential driven Laplace-Beltrami flows for biomolecular surface evolution and formation. The resulting surfaces are free of geometric singularities and minimize the total free energy of the biomolecular system. High order partial differential equation (PDE)-based nonlinear filters are employed for EMDB data processing. We show the efficacy of this approach in feature-preserving noise reduction. After the construction of protein multiresolution surfaces, we explore the analysis and characterization of surface morphology by using a variety of curvature definitions. Apart from the classical Gaussian curvature and mean curvature, maximum curvature, minimum curvature, shape index, and curvedness are also applied to macromolecular surface analysis for the first time. Our curvature analysis is uniquely coupled to the analysis of electrostatic surface potential, which is a by-product of our variational multiscale solvation models. As an expository investigation, we particularly emphasize the numerical algorithms and computational protocols for practical applications of the above multiscale geometric models. Such information may otherwise be scattered over the vast literature on this topic. Based on the curvature and electrostatic analysis from our multiresolution surfaces, we introduce a new concept, the
Geometric procedures for civil engineers
Tonias, Elias C
2016-01-01
This book provides a multitude of geometric constructions usually encountered in civil engineering and surveying practice. A detailed geometric solution is provided to each construction as well as a step-by-step set of programming instructions for incorporation into a computing system. The volume is comprised of 12 chapters and appendices that may be grouped in three major parts: the first is intended for those who love geometry for its own sake and its evolution through the ages, in general, and, more specifically, with the introduction of the computer. The second section addresses geometric features used in the book and provides support procedures used by the constructions presented. The remaining chapters and the appendices contain the various constructions. The volume is ideal for engineering practitioners in civil and construction engineering and allied areas.
Geometric scalar theory of gravity
Energy Technology Data Exchange (ETDEWEB)
Novello, M.; Bittencourt, E.; Goulart, E.; Salim, J.M.; Toniato, J.D. [Instituto de Cosmologia Relatividade Astrofisica ICRA - CBPF Rua Dr. Xavier Sigaud 150 - 22290-180 Rio de Janeiro - Brazil (Brazil); Moschella, U., E-mail: novello@cbpf.br, E-mail: eduhsb@cbpf.br, E-mail: Ugo.Moschella@uninsubria.it, E-mail: egoulart@cbpf.br, E-mail: jsalim@cbpf.br, E-mail: toniato@cbpf.br [Università degli Studi dell' Insubria - Dipartamento di Fisica e Matematica Via Valleggio 11 - 22100 Como - Italy (Italy)
2013-06-01
We present a geometric scalar theory of gravity. Our proposal will be described using the ''background field method'' introduced by Gupta, Feynman, Deser and others as a field theory formulation of general relativity. We analyze previous criticisms against scalar gravity and show how the present proposal avoids these difficulties. This concerns not only the theoretical complaints but also those related to observations. In particular, we show that the widespread belief of the conjecture that the source of scalar gravity must be the trace of the energy-momentum tensor — which is one of the main difficulties to couple gravity with electromagnetic phenomenon in previous models — does not apply to our geometric scalar theory. From the very beginning this is not a special relativistic scalar gravity. The adjective ''geometric'' pinpoints its similarity with general relativity: this is a metric theory of gravity. Some consequences of this new scalar theory are explored.
Geometric identities in stereological particle analysis
DEFF Research Database (Denmark)
Kötzer, S.; Jensen, Eva Bjørn Vedel; Baddeley, A.
We review recent findings about geometric identities in integral geometry and geometric tomography, and their statistical application to stereological particle analysis. Open questions are discussed.......We review recent findings about geometric identities in integral geometry and geometric tomography, and their statistical application to stereological particle analysis. Open questions are discussed....
Geometric orbit datum and orbit covers
Institute of Scientific and Technical Information of China (English)
梁科; 侯自新
2001-01-01
Vogan conjectured that the parabolic induction of orbit data is independent of the choice of the parabolic subgroup. In this paper we first give the parabolic induction of orbit covers, whose relationship with geometric orbit datum is also induced. Hence we show a geometric interpretation of orbit data and finally prove the conjugation for geometric orbit datum using geometric method.
Geometric formula for prism deflection
Indian Academy of Sciences (India)
Apoorva G Wagh; Veer Chand Rakhecha
2004-08-01
While studying neutron deflections produced by a magnetic prism, we have stumbled upon a simple `geometric' formula. For a prism of refractive index close to unity, the deflection simply equals the product of the refractive power − 1 and the base-to-height ratio of the prism, regardless of the apex angle. The base and height of the prism are measured respectively along and perpendicular to the direction of beam propagation within the prism. The geometric formula greatly simplifies the optimisation of prism parameters to suit any specific experiment.
A Geometric Formulation of Supersymmetry
Freedman, Daniel Z; Van Proeyen, Antoine
2016-01-01
The scalar fields of supersymmetric models are coordinates of a geometric space. We propose a formulation of supersymmetry that is covariant with respect to reparametrizations of this target space. Employing chiral multiplets as an example, we introduce modified supersymmetry variations and redefined auxiliary fields that transform covariantly under reparametrizations. The resulting action and transformation laws are manifestly covariant and highlight the geometric structure of the supersymmetric theory. The covariant methods are developed first for general theories (not necessarily supersymmetric) whose scalar fields are coordinates of a Riemannian target space.
Geometric integration for particle accelerators
Energy Technology Data Exchange (ETDEWEB)
Forest, Etienne [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
2006-05-12
This paper is a very personal view of the field of geometric integration in accelerator physics-a field where often work of the highest quality is buried in lost technical notes or even not published; one has only to think of Simon van der Meer Nobel prize work on stochastic cooling-unpublished in any refereed journal. So I reconstructed the relevant history of geometrical integration in accelerator physics as much as I could by talking to collaborators and using my own understanding of the field. The reader should not be too surprised if this account is somewhere between history, science and perhaps even fiction.
Geometric pumping in autophoretic channels
Michelin, Sebastien; De Canio, Gabriele; Lobato-Dauzier, Nicolas; Lauga, Eric
2015-01-01
Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory.
Asymptotic geometric analysis, part I
Artstein-Avidan, Shiri
2015-01-01
The authors present the theory of asymptotic geometric analysis, a field which lies on the border between geometry and functional analysis. In this field, isometric problems that are typical for geometry in low dimensions are substituted by an "isomorphic" point of view, and an asymptotic approach (as dimension tends to infinity) is introduced. Geometry and analysis meet here in a non-trivial way. Basic examples of geometric inequalities in isomorphic form which are encountered in the book are the "isomorphic isoperimetric inequalities" which led to the discovery of the "concentration phenomen
An introduction to geometrical physics
Aldrovandi, R
1995-01-01
This book stresses the unifying power of the geometrical framework in bringing together concepts from the different areas of physics. Common underpinnings of optics, elasticity, gravitation, relativistic fields, particle mechanics and other subjects are underlined. It attempts to extricate the notion of space currently in the physical literature from the metric connotation.The book's goal is to present mathematical ideas associated with geometrical physics in a rather introductory language. Included are many examples from elementary physics and also, for those wishing to reach a higher level o
Introduction to Cluster Monte Carlo Algorithms
Luijten, E.
This chapter provides an introduction to cluster Monte Carlo algorithms for classical statistical-mechanical systems. A brief review of the conventional Metropolis algorithm is given, followed by a detailed discussion of the lattice cluster algorithm developed by Swendsen and Wang and the single-cluster variant introduced by Wolff. For continuum systems, the geometric cluster algorithm of Dress and Krauth is described. It is shown how their geometric approach can be generalized to incorporate particle interactions beyond hardcore repulsions, thus forging a connection between the lattice and continuum approaches. Several illustrative examples are discussed.
Reconstruction of an InAs nanowire using geometric and algebraic tomography
DEFF Research Database (Denmark)
Pennington, Robert S.; König, S.; Alpers, A.;
2011-01-01
Geometric tomography and conventional algebraic tomography algorithms are used to reconstruct cross-sections of an InAs nanowire from a tilt series of experimental annular dark-field images. Both algorithms are also applied to a test object to assess what factors affect the reconstruction quality...
Constrained Calculus of Variations and Geometric Optimal Control Theory
Luria, Gianvittorio
2010-01-01
The present work provides a geometric approach to the calculus of variations in the presence of non-holonomic constraints. As far as the kinematical foundations are concerned, a fully covariant scheme is developed through the introduction of the concept of infinitesimal control. The usual classification of the evolutions into normal and abnormal ones is also discussed, showing the existence of a universal algorithm assigning to every admissible curve a corresponding abnormality index, defined...
Optimal Geometric Partitions, Covers and K-Centers
Andreica, Mugurel Ionut; Andreica, Cristina Teodora; Andreica, Romulus; Ungureanu, Mihai Aristotel
2009-01-01
In this paper we present some new, practical, geometric optimization techniques for computing polygon partitions, 1D and 2D point, interval, square and rectangle covers, as well as 1D and 2D interval and rectangle K-centers. All the techniques we present have immediate applications to several cost optimization and facility location problems which are quite common in practice. The main technique employed is dynamic programming, but we also make use of efficient data structures and fast greedy algorithms.
Optimal source codes for geometrically distributed integer alphabets
Gallager, R. G.; Van Voorhis, D. C.
1975-01-01
An approach is shown for using the Huffman algorithm indirectly to prove the optimality of a code for an infinite alphabet if an estimate concerning the nature of the code can be made. Attention is given to nonnegative integers with a geometric probability assignment. The particular distribution considered arises in run-length coding and in encoding protocol information in data networks. Questions of redundancy of the optimal code are also investigated.
Institute of Scientific and Technical Information of China (English)
张大兴; 张振洲
2012-01-01
针对机械比对力机的工艺和控制要求,详细介绍了SIMODRIVE 611A交流伺服驱动系统在机械比对力机上的应用.利用高性能的伺服定位模块FM354,控制交流伺服驱动系统,满足机械比对力机对速度、力矩和大调速范围的要求,使力机满足国家称重传感器检定规程( JJG669 - 90)和称重传感器生产检测要求.%Aimed at technics and control requirement of build-up standard machine,this paper introduced the appliance of SI-MODRIVE 611A AC servo system in build-up standard machine. It use high-powered servo orientation module FM354 to control AC servo drive system. It satisfies the speed,moment and timing range of build-up standard machine,and also satisfies verification regulation of weighing cell (JJG669 -90) and measure requirement of weighing cell in manufacture.
Energy Technology Data Exchange (ETDEWEB)
Pena, J [Departamento de Fisica de PartIculas, Universidade de Santiago de Compostela, Santiago de Compostela (Spain); Sanchez-Doblado, F [Hospital Universitario Virgen Macarena, RadioFisica, Sevilla (Spain); Departamento de FisiologIa y BioFisica, Facultad de Medicina, Universidad de Sevilla (Spain); Capote, R [International Atomic Energy Agency, Nuclear Data Section, Vienna (Austria); Terron, J A [Hospital Universitario Virgen Macarena, RadioFisica, Sevilla (Spain); Departamento de FisiologIa y BioFisica, Facultad de Medicina, Universidad de Sevilla (Spain); Gomez, F [Departamento de Fisica de PartIculas, Universidade de Santiago de Compostela, Santiago de Compostela (Spain)
2006-03-21
Reference dosimetry of photon fields is a well-established subject and currently available protocols (such as the IAEA TRS-398 and AAPM TG-51) provide methods for converting the ionization chamber (IC) reading into dose to water, provided reference conditions of charged particle equilibrium (CPE) are fulfilled. But these protocols cannot deal with the build-up region, where the lack of CPE limits the applicability of the cavity theorems and so the chamber correction factors become depth dependent. By explicitly including the IC geometry in the Monte Carlo simulations, depth-dependent dose correction factors are calculated for a PTW 30001 0.6 cm{sup 3} ion chamber in the build-up region of the 6 MV photon beam. The corrected percentage depth dose (PDD) agrees within 2% with that measured using the NACP 02 plane-parallel ion chamber in the build-up region at depths greater than 0.4 cm, where the Farmer chamber wall reaches the phantom surface.
SIFT based algorithm for point feature tracking
Directory of Open Access Journals (Sweden)
Adrian BURLACU
2007-12-01
Full Text Available In this paper a tracking algorithm for SIFT features in image sequences is developed. For each point feature extracted using SIFT algorithm a descriptor is computed using information from its neighborhood. Using an algorithm based on minimizing the distance between two descriptors tracking point features throughout image sequences is engaged. Experimental results, obtained from image sequences that capture scaling of different geometrical type object, reveal the performances of the tracking algorithm.
Loop Closing Detection in RGB-D SLAM Combining Appearance and Geometric Constraints
Directory of Open Access Journals (Sweden)
Heng Zhang
2015-06-01
Full Text Available A kind of multi feature points matching algorithm fusing local geometric constraints is proposed for the purpose of quickly loop closing detection in RGB-D Simultaneous Localization and Mapping (SLAM. The visual feature is encoded with BRAND (binary robust appearance and normals descriptor, which efficiently combines appearance and geometric shape information from RGB-D images. Furthermore, the feature descriptors are stored using the Locality-Sensitive-Hashing (LSH technique and hierarchical clustering trees are used to search for these binary features. Finally, the algorithm for matching of multi feature points using local geometric constraints is provided, which can effectively reject the possible false closure hypotheses. We demonstrate the efficiency of our algorithms by real-time RGB-D SLAM with loop closing detection in indoor image sequences taken with a handheld Kinect camera and comparative experiments using other algorithms in RTAB-Map dealing with a benchmark dataset.
Loop Closing Detection in RGB-D SLAM Combining Appearance and Geometric Constraints.
Zhang, Heng; Liu, Yanli; Tan, Jindong
2015-06-19
A kind of multi feature points matching algorithm fusing local geometric constraints is proposed for the purpose of quickly loop closing detection in RGB-D Simultaneous Localization and Mapping (SLAM). The visual feature is encoded with BRAND (binary robust appearance and normals descriptor), which efficiently combines appearance and geometric shape information from RGB-D images. Furthermore, the feature descriptors are stored using the Locality-Sensitive-Hashing (LSH) technique and hierarchical clustering trees are used to search for these binary features. Finally, the algorithm for matching of multi feature points using local geometric constraints is provided, which can effectively reject the possible false closure hypotheses. We demonstrate the efficiency of our algorithms by real-time RGB-D SLAM with loop closing detection in indoor image sequences taken with a handheld Kinect camera and comparative experiments using other algorithms in RTAB-Map dealing with a benchmark dataset.
In Defence of Geometrical Algebra
Blasjo, V.N.E.
2016-01-01
The geometrical algebra hypothesis was once the received interpretation of Greek mathematics. In recent decades, however, it has become anathema to many. I give a critical review of all arguments against it and offer a consistent rebuttal case against the modern consensus. Consequently, I find that
Metastable vacua and geometric deformations
Amariti, A; Girardello, L; Mariotti, A
2008-01-01
We study the geometric interpretation of metastable vacua for systems of D3 branes at non isolated toric deformable singularities. Using the L^{aba} examples, we investigate the relations between the field theoretic susy breaking and restoration and the complex deformations of the CY singularities.
Geometrical modeling of fibrous materials under compression
Maze, Benoit; Tafreshi, Hooman Vahedi; Pourdeyhimi, Behnam
2007-10-01
Many fibrous materials such as nonwovens are consolidated via compaction rolls in a so-called calendering process. Hot rolls compress the fiber assembly and cause fiber-to-fiber bonding resulting in a strong yet porous structure. In this paper, we describe an algorithm for generating three dimensional virtual fiberwebs and simulating the geometrical changes that happen to the structure during the calendering process. Fibers are assumed to be continuous filaments with square cross sections lying randomly in the x or y direction. The fibers are assumed to be flexible to allow bending over one another during the compression process. Lateral displacement is not allowed during the compaction process. The algorithm also does not allow the fibers to interpenetrate or elongate and so the mass of the fibers is conserved. Bending of the fibers is modeled either by considering a constant "slope of bending" or constant "span of bending." The influence of the bending parameters on the propagation of compression through the material's thickness is discussed. In agreement with our experimental observations, it was found that the average solid volume fraction profile across the thickness becomes U shaped after the calendering. The application of these virtual structures in studying transport phenomena in fibrous materials is also demonstrated.
Geometric Transformations in Engineering Geometry
Directory of Open Access Journals (Sweden)
I. F. Borovikov
2015-01-01
Full Text Available Recently, for business purposes, in view of current trends and world experience in training engineers, research and faculty staff there has been a need to transform traditional courses of descriptive geometry into the course of engineering geometry in which the geometrical transformations have to become its main section. On the basis of critical analysis the paper gives suggestions to improve a presentation technique of this section both in the classroom and in academic literature, extend an application scope of geometrical transformations to solve the position and metric tasks and simulation of surfaces, as well as to design complex engineering configurations, which meet a number of pre-specified conditions.The article offers to make a number of considerable amendments to the terms and definitions used in the existing courses of descriptive geometry. It draws some conclusions and makes the appropriate proposals on feasibility of coordination in teaching the movement transformation in the courses of analytical and descriptive geometry. This will provide interdisciplinary team teaching and allow students to be convinced that a combination of analytical and graphic ways to solve geometric tasks is useful and reasonable.The traditional sections of learning courses need to be added with a theory of projective and bi-rational transformations. In terms of application simplicity and convenience it is enough to consider the central transformations when solving the applied tasks. These transformations contain a beam of sub-invariant (low-invariant straight lines on which the invariant curve induces non-involution and involution projectivities. The expediency of nonlinear transformations application is shown in the article by a specific example of geometric modeling of the interfacing surface "spar-blade".Implementation of these suggestions will contribute to a real transformation of a traditional course of descriptive geometry to the engineering geometry
Geometrical Phases in Quantum Mechanics
Christian, Joy Julius
In quantum mechanics, the path-dependent geometrical phase associated with a physical system, over and above the familiar dynamical phase, was initially discovered in the context of adiabatically changing environments. Subsequently, Aharonov and Anandan liberated this phase from the original formulation of Berry, which used Hamiltonians, dependent on curves in a classical parameter space, to represent the cyclic variations of the environments. Their purely quantum mechanical treatment, independent of Hamiltonians, instead used the non-trivial topological structure of the projective space of one-dimensional subspaces of an appropriate Hilbert space. The geometrical phase, in their treatment, results from a parallel transport of the time-dependent pure quantum states along a curve in this space, which is endowed with an abelian connection. Unlike Berry, they were able to achieve this without resort to an adiabatic approximation or to a time-independent eigenvalue equation. Prima facie, these two approaches are conceptually quite different. After a review of both approaches, an exposition bridging this apparent conceptual gap is given; by rigorously analyzing a model composite system, it is shown that, in an appropriate correspondence limit, the Berry phase can be recovered as a special case from the Aharonov-Anandan phase. Moreover, the model composite system is used to show that Berry's correction to the traditional Born-Oppenheimer energy spectra indeed brings the spectra closer to the exact results. Then, an experimental arrangement to measure geometrical phases associated with cyclic and non-cyclic variations of quantum states of an entangled composite system is proposed, utilizing the fundamental ideas of the recently opened field of two-particle interferometry. This arrangement not only resolves the controversy regarding the true nature of the phases associated with photon states, but also unequivocally predicts experimentally accessible geometrical phases in a
Directory of Open Access Journals (Sweden)
Seppala Jan
2012-05-01
Full Text Available Abstract Background and purpose Stereotactic lung radiotherapy (SLRT has emerged as a curative treatment for medically inoperable patients with early-stage non-small cell lung cancer (NSCLC and the use of intensity-modulated radiotherapy (IMRT and volumetric modulated arc treatments (VMAT have been proposed as the best practical approaches for the delivery of SLRT. However, a large number of narrow field shapes are needed in the dose delivery of intensity-modulated techniques and the probability of underdosing the tumour periphery increases as the effective field size is decreased. The purpose of this study was to evaluate small lung tumour doses irradiated by intensity-modulated techniques to understand the risk for dose calculation errors in precision radiotherapy such as SLRT. Materials and methods The study was executed with two heterogeneous phantoms with targets of Ø1.5 and Ø4.0 cm. Dose distributions in the simulated tumours delivered by small sliding window apertures (SWAs, IMRT and RapidArc treatment plans were measured with radiochromic film. Calculation algorithms of pencil beam convolution (PBC and anisotropic analytic algorithm (AAA were used to calculate the corresponding dose distributions. Results Peripheral doses of the tumours were decreased as SWA decreased, which was not modelled by the calculation algorithms. The smallest SWA studied was 2 mm, which reduced the 90% isodose line width by 4.2 mm with the Ø4.0 cm tumour as compared to open field irradiation. PBC was not able to predict the dose accurately as the gamma evaluation failed to meet the criteria of ±3%/±1 mm on average in 61% of the defined volume with the smaller tumour. With AAA the corresponding value was 16%. The dosimetric inaccuracy of AAA was within ±3% with the optimized treatment plans of IMRT and RapidArc. The exception was the clinical RapidArc plan with dose overestimation of 4%. Conclusions Overall, the peripheral doses of the simulated
Guiding light via geometric phases
Slussarenko, Sergei; Jisha, Chandroth P; Piccirillo, Bruno; Santamato, Enrico; Assanto, Gaetano; Marrucci, Lorenzo
2015-01-01
Known methods for transverse confinement and guidance of light can be grouped into a few basic mechanisms, the most common being metallic reflection, total internal reflection and photonic-bandgap (or Bragg) reflection. All of them essentially rely on changes of the refractive index, that is on scalar properties of light. Recently, processes based on "geometric Berry phases", such as manipulation of polarization states or deflection of spinning-light rays, have attracted considerable interest in the contexts of singular optics and structured light. Here, we disclose a new approach to light waveguiding, using geometric Berry phases and exploiting polarization states and their handling. This can be realized in structured three-dimensional anisotropic media, in which the optic axis lies orthogonal to the propagation direction and is modulated along it and across the transverse plane, so that the refractive index remains constant but a phase distortion can be imposed on a beam. In addition to a complete theoretic...
Geometrical Aspects of Venus Transit
Bertuola, Alberto C; Magalhães, N S; Filho, Victo S
2016-01-01
We obtained two astronomical values, the Earth-Venus distance and Venus diameter, by means of a geometrical treatment of photos taken of Venus transit in June of 2012. Here we presented the static and translational modelsthat were elaborated taking into account the Earth and Venus orbital movements. An additional correction was also added by considering the Earth rotation movement. The results obtained were compared with the values of reference from literature, showing very good concordance.
Geometric Hyperplanes: Desargues Encodes Doily
Saniga, Metod
2011-01-01
It is shown that the structure of the generalized quadrangle of order two is fully encoded in the properties of the Desargues configuration. A point of the quadrangle is represented by a geometric hyperplane of the Desargues configuration and its line by a set of three hyperplanes such that one of them is the complement of the symmetric difference of the remaining two and they all share a pair of non-collinear points.
Geometrical interpretation of optical absorption
Energy Technology Data Exchange (ETDEWEB)
Monzon, J. J.; Barriuso, A. G.; Sanchez-Soto, L. L. [Departamento de Optica, Facultad de Fisica, Universidad Complutense, E-28040 Madrid (Spain); Montesinos-Amilibia, J. M. [Departamento de Geometria y Topologia, Facultad de Matematicas, Universidad Complutense, E-28040 Madrid (Spain)
2011-08-15
We reinterpret the transfer matrix for an absorbing system in very simple geometrical terms. In appropriate variables, the system appears as performing a Lorentz transformation in a (1 + 3)-dimensional space. Using homogeneous coordinates, we map that action on the unit sphere, which is at the realm of the Klein model of hyperbolic geometry. The effects of absorption appear then as a loxodromic transformation, that is, a rhumb line crossing all the meridians at the same angle.
The Geometry of Algorithms with Orthogonality Constraints
Edelman, A; Smith, S T; Edelman, Alan; Smith, Steven T.
1998-01-01
In this paper we develop new Newton and conjugate gradient algorithms on the Grassmann and Stiefel manifolds. These manifolds represent the constraints that arise in such areas as the symmetric eigenvalue problem, nonlinear eigenvalue problems, electronic structures computations, and signal processing. In addition to the new algorithms, we show how the geometrical framework gives penetrating new insights allowing us to create, understand, and compare algorithms. The theory proposed here provides a taxonomy for numerical linear algebra algorithms that provide a top level mathematical view of previously unrelated algorithms. It is our hope that developers of new algorithms and perturbation theories will benefit from the theory, methods, and examples in this paper.
Robust image watermarking scheme against geometric attacks using a computer-generated hologram.
Li, Jianzhong
2010-11-10
Robustness against geometric attacks is one of the most important issues in digital watermarking. A novel geometric robust watermarking scheme that uses computer-generated holograms as the watermark is presented. To maintain imperceptibility and robustness, a quantization embedding algorithm is adopted to embed the mark hologram into the low-frequency subband of the wavelet-transformed host image. In the detection process, the geometric distorted watermarked images are recovered first by the proposed improved geometric correction method, which is based on the scale invariant feature transform, the invariant centroid, and the pulse coupled neural network. Then the mark holograms are extracted from the recovered images. In comparison with the traditional geometric estimation method, the suggested improved geometric correction method can estimate the geometric distortion parameters more accurately and needs less auxiliary information. Compared with other watermark schemes using digital holograms, the proposed method has the distinct advantage of robustness to geometric attacks. The experimental results demonstrate that the proposed method has good robustness to resist geometric attacks and common attacks including rotation, scaling, translation, image flipping, combined attacks, filtering, occlusion, cropping, and JPEG compression.
Polar metals by geometric design
Kim, T. H.; Puggioni, D.; Yuan, Y.; Xie, L.; Zhou, H.; Campbell, N.; Ryan, P. J.; Choi, Y.; Kim, J.-W.; Patzner, J. R.; Ryu, S.; Podkaminer, J. P.; Irwin, J.; Ma, Y.; Fennie, C. J.; Rzchowski, M. S.; Pan, X. Q.; Gopalan, V.; Rondinelli, J. M.; Eom, C. B.
2016-05-01
Gauss’s law dictates that the net electric field inside a conductor in electrostatic equilibrium is zero by effective charge screening; free carriers within a metal eliminate internal dipoles that may arise owing to asymmetric charge distributions. Quantum physics supports this view, demonstrating that delocalized electrons make a static macroscopic polarization, an ill-defined quantity in metals—it is exceedingly unusual to find a polar metal that exhibits long-range ordered dipoles owing to cooperative atomic displacements aligned from dipolar interactions as in insulating phases. Here we describe the quantum mechanical design and experimental realization of room-temperature polar metals in thin-film ANiO3 perovskite nickelates using a strategy based on atomic-scale control of inversion-preserving (centric) displacements. We predict with ab initio calculations that cooperative polar A cation displacements are geometrically stabilized with a non-equilibrium amplitude and tilt pattern of the corner-connected NiO6 octahedra—the structural signatures of perovskites—owing to geometric constraints imposed by the underlying substrate. Heteroepitaxial thin-films grown on LaAlO3 (111) substrates fulfil the design principles. We achieve both a conducting polar monoclinic oxide that is inaccessible in compositionally identical films grown on (001) substrates, and observe a hidden, previously unreported, non-equilibrium structure in thin-film geometries. We expect that the geometric stabilization approach will provide novel avenues for realizing new multifunctional materials with unusual coexisting properties.
Geometric algebra and information geometry for quantum computational software
Cafaro, Carlo
2017-03-01
The art of quantum algorithm design is highly nontrivial. Grover's search algorithm constitutes a masterpiece of quantum computational software. In this article, we use methods of geometric algebra (GA) and information geometry (IG) to enhance the algebraic efficiency and the geometrical significance of the digital and analog representations of Grover's algorithm, respectively. Specifically, GA is used to describe the Grover iterate and the discretized iterative procedure that exploits quantum interference to amplify the probability amplitude of the target-state before measuring the query register. The transition from digital to analog descriptions occurs via Stone's theorem which relates the (unitary) Grover iterate to a suitable (Hermitian) Hamiltonian that controls Schrodinger's quantum mechanical evolution of a quantum state towards the target state. Once the discrete-to-continuos transition is completed, IG is used to interpret Grover's iterative procedure as a geodesic path on the manifold of the parametric density operators of pure quantum states constructed from the continuous approximation of the parametric quantum output state in Grover's algorithm. Finally, we discuss the dissipationless nature of quantum computing, recover the quadratic speedup relation, and identify the superfluity of the Walsh-Hadamard operation from an IG perspective with emphasis on statistical mechanical considerations.
NOVEL RADAR SIGNAL SORTING METHOD BASED ON GEOMETRIC COVERING
Institute of Scientific and Technical Information of China (English)
万建; 国强; 宋文明
2013-01-01
With the increase of complexity of electromagnetic environment and continuous appearance of advanced system radars ,signals received by radar reconnaissance receivers become even more intensive and complex .There-fore ,traditional radar sorting methods based on neural network algorithms and support vector machine (SVM ) cannot process them effectively .Aiming at solving this problem ,a novel radar signal sorting method based on the cloud model theory and the geometric covering algorithm is proposed .By applying the geometric covering algo-rithm to divide input signals into different covering domains based on their distribution characteristics ,the method can overcome a typical problem that it is easy for traditional sorting algorithms to fall into the local extrema due to the use of complex nonlinear equation to describe input signals .The method uses the cloud model to describe the membership degree between signals to be sorted and their covering domains ,thus it avoids the disadvantage that traditional sorting methods based on hard clustering cannot deinterleave the signal samples with overlapped param-eters .Experimental results show that the presented method can effectively sort advanced system radar signals with overlapped parameters in complex electromagnetic environment .
Cooperated Bayesian algorithm for distributed scheduling problem
Institute of Scientific and Technical Information of China (English)
QIANG Lei; XIAO Tian-yuan
2006-01-01
This paper presents a new distributed Bayesian optimization algorithm (BOA) to overcome the efficiency problem when solving NP scheduling problems.The proposed approach integrates BOA into the co-evolutionary schema,which builds up a concurrent computing environment.A new search strategy is also introduced for local optimization process.It integrates the reinforcement learning(RL) mechanism into the BOA search processes,and then uses the mixed probability information from BOA (post-probability) and RL (pre-probability) to enhance the cooperation between different local controllers,which improves the optimization ability of the algorithm.The experiment shows that the new algorithm does better in both optimization (2.2%) and convergence (11.7%),compared with classic BOA.
Some geometrical iteration methods for nonlinear equations
Institute of Scientific and Technical Information of China (English)
LU Xing-jiang; QIAN Chun
2008-01-01
This paper describes geometrical essentials of some iteration methods (e.g. Newton iteration,secant line method,etc.) for solving nonlinear equations and advances some geomet-rical methods of iteration that are flexible and efficient.
Institute of Scientific and Technical Information of China (English)
CHEN Gui-ming; WANG Han-gong; ZHANG Bao-jun; PAN Wei
2003-01-01
This paper analyzes the potential color formats of ferrograph images, and presents the algorithms of converting the formats to RGB(Red, Green, Blue) color space. Through statistical analysis of wear par-ticles' geometric features of color ferrograph images in the RGB color space, we give the differences of ferro-graph wear panicles' geometric features among RGB color spaces and gray scale space, and calculate their respective distributions.
Adiabatic geometric phases in hydrogenlike atoms
Sjöqvist, Erik; Yi, X. X.; Åberg, J.
2005-01-01
We examine the effect of spin-orbit coupling on geometric phases in hydrogenlike atoms exposed to a slowly varying magnetic field. The marginal geometric phases associated with the orbital angular momentum and the intrinsic spin fulfill a sum rule that explicitly relates them to the corresponding geometric phase of the whole system. The marginal geometric phases in the Zeeman and Paschen-Back limit are analyzed. We point out the existence of nodal points in the marginal phases that may be det...
Development of a Geometric Spatial Visualization Tool
Ganesh, Bibi; Wilhelm, Jennifer; Sherrod, Sonya
2009-01-01
This paper documents the development of the Geometric Spatial Assessment. We detail the development of this instrument which was designed to identify middle school students' strategies and advancement in understanding of four geometric concept domains (geometric spatial visualization, spatial projection, cardinal directions, and periodic patterns)…
Exact Solutions for Einstein's Hyperbolic Geometric Flow
Institute of Scientific and Technical Information of China (English)
HE Chun-Lei
2008-01-01
In this paper we investigate the Einstein's hyperbolic geometric flow and obtain some interesting exact solutions for this kind of flow. Many interesting properties of these exact solutions have also been analyzed and we believe that these properties of Einstein's hyperbolic geometric flow are very helpful to understanding the Einstein equations and the hyperbolic geometric flow.
Generalized geometrically convex functions and inequalities.
Noor, Muhammad Aslam; Noor, Khalida Inayat; Safdar, Farhat
2017-01-01
In this paper, we introduce and study a new class of generalized functions, called generalized geometrically convex functions. We establish several basic inequalities related to generalized geometrically convex functions. We also derive several new inequalities of the Hermite-Hadamard type for generalized geometrically convex functions. Several special cases are discussed, which can be deduced from our main results.
DEFF Research Database (Denmark)
Keck, Rolf-Erik; de Mare, Martin Tobias; Churchfield, Matthew J.
2015-01-01
the model to simulate the build-up of turbulence over a row of turbines in a physically consistent manner. The performance of the modified model is validated against actuator line (AL) model results and field data from the Lillgrund offshore wind farm. Qualitatively, the modified DWM model is in fair......%, respectively, by including the proposed corrections for a row of eight turbines. Furthermore, it is found that the root-mean-square difference between the AL model and the modified DWM model in terms of wind speed and turbulence intensity does not increase over a row of turbines compared with the root...
A Geometric Approach for Multi-Degree Spline
Institute of Scientific and Technical Information of China (English)
Xin Li; Zhang-Jin Huang; Zhao Liu
2012-01-01
Multi-degree spline (MD-spline for short) is a generalization of B-spline which comprises of polynomial segments of various degrees.The present paper provides a new definition for MD-spline curves in a geometric intuitive way based on an efficient and simple evaluation algorithm.MD-spline curves maintain various desirable properties of B-spline curves,such as convex hull,local support and variation diminishing properties.They can also be refined exactly with knot insertion.The continuity between two adjacent segments with different degrees is at least C1 and that between two adjacent segments of same degrees d is Cd-1.Benefited by the exact refinement algorithm,we also provide several operators for MD-spline curves,such as converting each curve segment into Bézier form,an efficient merging algorithm and a new curve subdivision scheme which allows different degrees for each segment.
Brachytherapy seed localization using geometric and linear programming techniques.
Singh, Vikas; Mukherjee, Lopamudra; Xu, Jinhui; Hoffmann, Kenneth R; Dinu, Petru M; Podgorsak, Matthew
2007-09-01
We propose an optimization algorithm to solve the brachytherapy seed localization problem in prostate brachytherapy. Our algorithm is based on novel geometric approaches to exploit the special structure of the problem and relies on a number of key observations which help us formulate the optimization problem as a minimization integer program (IP). Our IP model precisely defines the feasibility polyhedron for this problem using a polynomial number of half-spaces; the solution to its corresponding linear program is rounded to yield an integral solution to our task of determining correspondences between seeds in multiple projection images. The algorithm is efficient in theory as well as in practice and performs well on simulation data (approximately 98% accuracy) and real X-ray images (approximately 95% accuracy). We present in detail the underlying ideas and an extensive set of performance evaluations based on our implementation.
Geometric MCMC for infinite-dimensional inverse problems
Beskos, Alexandros; Girolami, Mark; Lan, Shiwei; Farrell, Patrick E.; Stuart, Andrew M.
2017-04-01
Bayesian inverse problems often involve sampling posterior distributions on infinite-dimensional function spaces. Traditional Markov chain Monte Carlo (MCMC) algorithms are characterized by deteriorating mixing times upon mesh-refinement, when the finite-dimensional approximations become more accurate. Such methods are typically forced to reduce step-sizes as the discretization gets finer, and thus are expensive as a function of dimension. Recently, a new class of MCMC methods with mesh-independent convergence times has emerged. However, few of them take into account the geometry of the posterior informed by the data. At the same time, recently developed geometric MCMC algorithms have been found to be powerful in exploring complicated distributions that deviate significantly from elliptic Gaussian laws, but are in general computationally intractable for models defined in infinite dimensions. In this work, we combine geometric methods on a finite-dimensional subspace with mesh-independent infinite-dimensional approaches. Our objective is to speed up MCMC mixing times, without significantly increasing the computational cost per step (for instance, in comparison with the vanilla preconditioned Crank-Nicolson (pCN) method). This is achieved by using ideas from geometric MCMC to probe the complex structure of an intrinsic finite-dimensional subspace where most data information concentrates, while retaining robust mixing times as the dimension grows by using pCN-like methods in the complementary subspace. The resulting algorithms are demonstrated in the context of three challenging inverse problems arising in subsurface flow, heat conduction and incompressible flow control. The algorithms exhibit up to two orders of magnitude improvement in sampling efficiency when compared with the pCN method.
D Image Based Geometric Documentation of the Tower of Winds
Tryfona, M. S.; Georgopoulos, A.
2016-06-01
This paper describes and investigates the implementation of almost entirely image based contemporary techniques for the three dimensional geometric documentation of the Tower of the Winds in Athens, which is a unique and very special monument of the Roman era. These techniques and related algorithms were implemented using a well-known piece of commercial software with extreme caution in the selection of the various parameters. Problems related to data acquisition and processing, but also to the algorithms and to the software implementation are identified and discussed. The resulting point cloud has been georeferenced, i.e. referenced to a local Cartesian coordinate system through minimum geodetic measurements, and subsequently the surface, i.e. the mesh was created and finally the three dimensional textured model was produced. In this way, the geometric documentation drawings, i.e. the horizontal section plans, the vertical section plans and the elevations, which include orthophotos of the monument, can be produced at will from that 3D model, for the complete geometric documentation. Finally, a 3D tour of the Tower of the Winds has also been created for a more integrated view of the monument. The results are presented and are evaluated for their completeness, efficiency, accuracy and ease of production.
Ratschek, H
2003-01-01
This undergraduate and postgraduate text will familiarise readers with interval arithmetic and related tools to gain reliable and validated results and logically correct decisions for a variety of geometric computations plus the means for alleviating the effects of the errors. It also considers computations on geometric point-sets, which are neither robust nor reliable in processing with standard methods. The authors provide two effective tools for obtaining correct results: (a) interval arithmetic, and (b) ESSA the new powerful algorithm which improves many geometric computations and makes th
Airborne Linear Array Image Geometric Rectification Method Based on Unequal Segmentation
Li, J. M.; Li, C. R.; Zhou, M.; Hu, J.; Yang, C. M.
2016-06-01
As the linear array sensor such as multispectral and hyperspectral sensor has great potential in disaster monitoring and geological survey, the quality of the image geometric rectification should be guaranteed. Different from the geometric rectification of airborne planar array images or multi linear array images, exterior orientation elements need to be determined for each scan line of single linear array images. Internal distortion persists after applying GPS/IMU data directly to geometrical rectification. Straight lines may be curving and jagged. Straight line feature -based geometrical rectification algorithm was applied to solve this problem, whereby the exterior orientation elements were fitted by piecewise polynomial and evaluated with the straight line feature as constraint. However, atmospheric turbulence during the flight is unstable, equal piecewise can hardly provide good fitting, resulting in limited precision improvement of geometric rectification or, in a worse case, the iteration cannot converge. To solve this problem, drawing on dynamic programming ideas, unequal segmentation of line feature-based geometric rectification method is developed. The angle elements fitting error is minimized to determine the optimum boundary. Then the exterior orientation elements of each segment are fitted and evaluated with the straight line feature as constraint. The result indicates that the algorithm is effective in improving the precision of geometric rectification.
Polar Metals by Geometric Design
Energy Technology Data Exchange (ETDEWEB)
Kim, T. H.; Puggioni, D.; Yuan, Y.; Xie, L.; Zhou, H.; Campbell, N.; Ryan, P. J.; Choi, Y.; Kim, J. -W.; Patzner, J. R.; Ryu, S.; Podkaminer, J. P.; Irwin, J.; Ma, Y.; Fennie, C. J.; Rzchowski, M. S.; Pan, X. Q.; Gopalan, V.; Rondinelli, J. M.; Eom, C. B.
2016-05-05
Gauss's law dictates that the net electric field inside a conductor in electrostatic equilibrium is zero by effective charge screening; free carriers within a metal eliminate internal dipoles that may arise owing to asymmetric charge distributions(1). Quantum physics supports this view(2), demonstrating that delocalized electrons make a static macroscopic polarization, an ill-defined quantity in metals(3)-it is exceedingly unusual to find a polar metal that exhibits long-range ordered dipoles owing to cooperative atomic displacements aligned from dipolar interactions as in insulating phases(4). Here we describe the quantum mechanical design and experimental realization of room-temperature polar metals in thin-film ANiO(3) perovskite nickelates using a strategy based on atomic-scale control of inversion-preserving (centric) displacements(5). We predict with ab initio calculations that cooperative polar A cation displacements are geometrically stabilized with a non-equilibrium amplitude and tilt pattern of the corner-connected NiO6 octahedra-the structural signatures of perovskites-owing to geometric constraints imposed by the underlying substrate. Heteroepitaxial thin-films grown on LaAlO3 (111) substrates fulfil the design principles. We achieve both a conducting polar monoclinic oxide that is inaccessible in compositionally identical films grown on (001) substrates, and observe a hidden, previously unreported(6-10), non-equilibrium structure in thin-film geometries. We expect that the geometric stabilization approach will provide novel avenues for realizing new multifunctional materials with unusual coexisting properties.
Field guide to geometrical optics
Greivenkamp, John E
2004-01-01
This Field Guide derives from the treatment of geometrical optics that has evolved from both the undergraduate and graduate programs at the Optical Sciences Center at the University of Arizona. The development is both rigorous and complete, and it features a consistent notation and sign convention. This volume covers Gaussian imagery, paraxial optics, first-order optical system design, system examples, illumination, chromatic effects, and an introduction to aberrations. The appendices provide supplemental material on radiometry and photometry, the human eye, and several other topics.
A history of geometrical methods
Coolidge, Julian Lowell
2013-01-01
Full and authoritative, this history of the techniques for dealing with geometric questions begins with synthetic geometry and its origins in Babylonian and Egyptian mathematics; reviews the contributions of China, Japan, India, and Greece; and discusses the non-Euclidean geometries. Subsequent sections cover algebraic geometry, starting with the precursors and advancing to the great awakening with Descartes; and differential geometry, from the early work of Huygens and Newton to projective and absolute differential geometry. The author's emphasis on proofs and notations, his comparisons betwe
Science, Art and Geometrical Imagination
Luminet, J -P
2009-01-01
From the geocentric, closed world model of Antiquity to the wraparound universe models of relativistic cosmology, the parallel history of space representations in science and art illustrates the fundamental role of geometric imagination in innovative findings. Through the analysis of works of various artists and scientists like Plato, Durer, Kepler, Escher, Grisey or the present author, it is shown how the process of creation in science and in the arts rests on aesthetical principles such as symmetry, regular polyhedra, laws of harmonic proportion, tessellations, group theory, etc., as well as beauty, conciseness and emotional approach of the world.
Science, art and geometrical imagination
Luminet, Jean-Pierre
2011-06-01
From the geocentric, closed world model of Antiquity to the wraparound universe models of relativistic cosmology, the parallel history of space representations in science and art illustrates the fundamental rôle of geometric imagination in innovative findings. Through the analysis of works of various artists and scientists like Plato, Dürer, Kepler, Escher, Grisey or the author, it is shown how the process of creation in science and in the arts rests on aesthetical principles such as symmetry, regular polyhedra, laws of harmonic proportion, tessellations, group theory, etc., as well as on beauty, conciseness and an emotional approach of the world.
Hubbard model with geometrical frustration
Energy Technology Data Exchange (ETDEWEB)
Lee, Hunpyo
2009-10-15
At first we present the details of the dual fermion (DF), the cluster extension of dynamical mean field theory (CDMFT) and continuous-time quantum Monte Carlo (CT QMC) methods. Using a panoply of these methods we explore the Hubbard model on the triangular and hyperkagome lattice. We find a first-order transition and continuous transition on the triangular and hyper-kagome lattice, respectively. Moreover, we find the reentrant behavior due to competition between the magnetic correlation and itinerancy of electrons by source of geometrical frustration on both lattices. (orig.)
Buildings, spiders, and geometric Satake
Fontaine, Bruce; Kuperberg, Greg
2011-01-01
Let G be a simple algebraic group. Labelled trivalent graphs called webs can be used to product invariants in tensor products of minuscule representations. For each web, we construct a configuration space of points in the affine Grassmannian. Via the geometric Satake correspondence, we relate these configuration spaces to the invariant vectors coming from webs. In the case G = SL(3), non-elliptic webs yield a basis for the invariant spaces. The non-elliptic condition, which is equivalent to the condition that the dual diskoid of the web is CAT(0), is explained by the fact that affine buildings are CAT(0).
Geometric Topology and Shape Theory
Segal, Jack
1987-01-01
The aim of this international conference the third of its type was to survey recent developments in Geometric Topology and Shape Theory with an emphasis on their interaction. The volume contains original research papers and carefully selected survey of currently active areas. The main topics and themes represented by the papers of this volume include decomposition theory, cell-like mappings and CE-equivalent compacta, covering dimension versus cohomological dimension, ANR's and LCn-compacta, homology manifolds, embeddings of continua into manifolds, complement theorems in shape theory, approximate fibrations and shape fibrations, fibered shape, exact homologies and strong shape theory.
New Iterative Learning Control Algorithms Based on Vector Plots Analysis1）
Institute of Scientific and Technical Information of China (English)
XIESheng-Li; TIANSen-Ping; XIEZhen-Dong
2004-01-01
Based on vector plots analysis, this paper researches the geometric frame of iterativelearning control method. New structure of iterative learning algorithms is obtained by analyzingthe vector plots of some general algorithms. The structure of the new algorithm is different fromthose of the present algorithms. It is of faster convergence speed and higher accuracy. Simulationspresented here illustrate the effectiveness and advantage of the new algorithm.
A Geometric Analysis of Subspace Clustering with Outliers
Soltanolkotabi, Mahdi
2011-01-01
This paper considers the problem of clustering a collection of unlabeled data points assumed to lie near a union of lower dimensional planes. As is common in computer vision or unsupervised learning applications, we do not know in advance how many subspaces there are nor do we have any information about their dimensions. We develop a novel geometric analysis of an algorithm named {\\em sparse subspace clustering} (SSC) \\cite{Elhamifar09}, which significantly broadens the range of problems where it is provably effective. For instance, we show that SSC can recover multiple subspaces, each of dimension comparable to the ambient dimension. We also prove that SSC can correctly cluster data points even when the subspaces of interest intersect. Further, we develop an extension of SSC that succeeds when the data set is corrupted with possibly overwhelmingly many outliers. Underlying our analysis are clear geometric insights, which may bear on other sparse recovery problems. A numerical study complements our theoretica...
Geometric integrator for simulations in the canonical ensemble
Tapias, Diego; Bravetti, Alessandro
2016-01-01
In this work we introduce a geometric integrator for molecular dynamics simulations of physical systems in the canonical ensemble. In particular, we consider the equations arising from the so-called density dynamics algorithm with any possible type of thermostat and provide an integrator that preserves the invariant distribution. Our integrator thus constitutes a unified framework that allows the study and comparison of different thermostats and of their influence on the equilibrium and non-equilibrium (thermo-)dynamic properties of the system. To show the validity and the generality of the integrator, we implement it with a second-order, time-reversible method and apply it to the simulation of a Lennard-Jones system with three different thermostats, obtaining good conservation of the geometrical properties and recovering the expected thermodynamic results.
Electric nonadiabatic geometric entangling gates on spin qubits
Azimi Mousolou, Vahid
2017-07-01
Producing and maintaining entanglement reside at the heart of the optimal construction of quantum operations and are fundamental issues in the realization of universal quantum computation. We here introduce a setup of spin qubits that allows the geometric implementation of entangling gates between the register qubits with any arbitrary entangling power. We show this by demonstrating a circuit through a spin chain, which performs universal nonadiabatic holonomic two-qubit entanglers. The proposed gates are all electric and geometric, which would help to realize fast and robust entangling gates on spin qubits. This family of entangling gates contains gates that are as efficient as the cnot gate in quantum algorithms. We examine the robustness of the circuit to some extent.
Geometric Modeling of Inclusions as Ellipsoids
Bonacuse, Peter J.
2008-01-01
Nonmetallic inclusions in gas turbine disk alloys can have a significant detrimental impact on fatigue life. Because large inclusions that lead to anomalously low lives occur infrequently, probabilistic approaches can be utilized to avoid the excessively conservative assumption of lifing to a large inclusion in a high stress location. A prerequisite to modeling the impact of inclusions on the fatigue life distribution is a characterization of the inclusion occurrence rate and size distribution. To help facilitate this process, a geometric simulation of the inclusions was devised. To make the simulation problem tractable, the irregularly sized and shaped inclusions were modeled as arbitrarily oriented, three independent dimensioned, ellipsoids. Random orientation of the ellipsoid is accomplished through a series of three orthogonal rotations of axes. In this report, a set of mathematical models for the following parameters are described: the intercepted area of a randomly sectioned ellipsoid, the dimensions and orientation of the intercepted ellipse, the area of a randomly oriented sectioned ellipse, the depth and width of a randomly oriented sectioned ellipse, and the projected area of a randomly oriented ellipsoid. These parameters are necessary to determine an inclusion s potential to develop a propagating fatigue crack. Without these mathematical models, computationally expensive search algorithms would be required to compute these parameters.
GEOMETRIC TURBULENCE IN GENERAL RELATIVITY
Directory of Open Access Journals (Sweden)
Trunev A. P.
2015-03-01
Full Text Available The article presents the simulation results of the metric of elementary particles, atoms, stars and galaxies in the general theory of relativity and Yang-Mills theory. We have shown metrics and field equations describing the transition to turbulence. The problems of a unified field theory with the turbulent fluctuations of the metric are considered. A transition from the Einstein equations to the diffusion equation and the Schrödinger equation in quantum mechanics is shown. Ther are examples of metrics in which the field equations are reduced to a single equation, it changes type depending on the equation of state. These examples can be seen as a transition to the geometric turbulence. It is shown that the field equations in general relativity can be reduced to a hyperbolic, elliptic or parabolic type. The equation of parabolic type describing the perturbations of the gravitational field on the scale of stars, galaxies and clusters of galaxies, which is a generalization of the theory of gravitation Newton-Poisson in case of Riemannian geometry, taking into account the curvature of space-time has been derived. It was found that the geometric turbulence leads to an exchange between regions of different scale. Under turbulent exchange material formed of two types of clusters, having positive and negative energy density that corresponds to the classical and quantum particle motion respectively. These results allow us to answer the question about the origin of the quantum theory
Geometric decompositions of collective motion
Mischiati, Matteo; Krishnaprasad, P. S.
2017-04-01
Collective motion in nature is a captivating phenomenon. Revealing the underlying mechanisms, which are of biological and theoretical interest, will require empirical data, modelling and analysis techniques. Here, we contribute a geometric viewpoint, yielding a novel method of analysing movement. Snapshots of collective motion are portrayed as tangent vectors on configuration space, with length determined by the total kinetic energy. Using the geometry of fibre bundles and connections, this portrait is split into orthogonal components each tangential to a lower dimensional manifold derived from configuration space. The resulting decomposition, when interleaved with classical shape space construction, is categorized into a family of kinematic modes-including rigid translations, rigid rotations, inertia tensor transformations, expansions and compressions. Snapshots of empirical data from natural collectives can be allocated to these modes and weighted by fractions of total kinetic energy. Such quantitative measures can provide insight into the variation of the driving goals of a collective, as illustrated by applying these methods to a publicly available dataset of pigeon flocking. The geometric framework may also be profitably employed in the control of artificial systems of interacting agents such as robots.
Measurement error in geometric morphometrics.
Fruciano, Carmelo
2016-06-01
Geometric morphometrics-a set of methods for the statistical analysis of shape once saluted as a revolutionary advancement in the analysis of morphology -is now mature and routinely used in ecology and evolution. However, a factor often disregarded in empirical studies is the presence and the extent of measurement error. This is potentially a very serious issue because random measurement error can inflate the amount of variance and, since many statistical analyses are based on the amount of "explained" relative to "residual" variance, can result in loss of statistical power. On the other hand, systematic bias can affect statistical analyses by biasing the results (i.e. variation due to bias is incorporated in the analysis and treated as biologically-meaningful variation). Here, I briefly review common sources of error in geometric morphometrics. I then review the most commonly used methods to measure and account for both random and non-random measurement error, providing a worked example using a real dataset.
Spanners for geometric intersection graphs with applications
Directory of Open Access Journals (Sweden)
Martin Fürer
2012-05-01
Full Text Available A ball graph is an intersection graph of a set of balls with arbitrary radii. Given a real numbert>1, we say that a subgraph G' of a graph G is a t-spanner of G, if for every pair of verticesu,v in G, there exists a path in G' of length at most t times the distance between u and v inG. In this paper, we consider the problem of efficiently constructing sparse spanners of ball graphs which supports fast shortest path distance queries.We present the first algorithm for constructing spanners of ball graphs. For a ball graph in Rk, we construct a (1+ε-spanner for any ε>0 with O(nε-k+1 edges in O(n2ℓ+δε-k logℓ S time, using an efficient partitioning of space into hypercubes and solving intersection problems. Here ℓ=1-1/(⌊k/2⌋+2, δ is any positive constant, and S is the ratio between the largest and smallest radius. For the special case when the balls all have unit size, we show that the complexity of constructing a (1+ε-spanner is almost equal to the complexity of constructing a Euclidean minimum spanning tree. The algorithm extends naturally to other disk-likeobjects, also in higher dimensions.The algorithm uses an efficient subdivision of space to construct a sparse graph having many of the same distance properties as the input ball graph. Additionally, the constructed spanners have a small vertex separator decomposition (hereditary. In dimension k=2, the disk graph spanner has an O(n1/2ε-3/2+ε-3log S separator. The presence of a small separator is then exploited to obtain very efficient data structures for approximate distance queries. The results on geometric graph separators might be of independent interest. For example, since complete Euclidean graphs are just a special case of (unit ball graphs, our results also provide a new approach for constructing spanners with small separators in these graphs.
Geometrical charged-particle optics
Rose, Harald H
2009-01-01
This reference monograph covers all theoretical aspects of modern geometrical charged-particle optics. It is intended as a guide for researchers, who are involved in the design of electron optical instruments and beam-guiding systems for charged particles, and as a tutorial for graduate students seeking a comprehensive treatment. Procedures for calculating the properties of systems with arbitrarily curved axes are outlined in detail and methods are discussed for designing and optimizing special components such as aberration correctors, spectrometers, energy filters, monochromators, ion traps, electron mirrors and cathode lenses. Also addressed is the design of novel electron optical components enabling sub-Angstroem spatial resolution and sub-0.1eV energy resolution. Relativistic motion and spin precession of the electron is treated in a concise way by employing a covariant five-dimensional procedure.
On chromatic and geometrical calibration
DEFF Research Database (Denmark)
Folm-Hansen, Jørgen
1999-01-01
of non-uniformity of the illumination of the image plane. Only the image deforming aberrations and the non-uniformity of illumination are included in the calibration models. The topics of the pinhole camera model and the extension to the Direct Linear Transform (DLT) are described. It is shown how......The main subject of the present thesis is different methods for the geometrical and chromatic calibration of cameras in various environments. For the monochromatic issues of the calibration we present the acquisition of monochrome images, the classic monochrome aberrations and the various sources...... the DLT can be extended with non-linear models of the common lens aberrations/errors some of them caused by manufacturing defects like decentering and thin prism distortion. The relation between a warping and the non-linear defects are shown. The issue of making a good resampling of an image by using...
Geometrical charged-particle optics
Rose, Harald
2012-01-01
This second edition is an extended version of the first edition of Geometrical Charged-Particle Optics. The updated reference monograph is intended as a guide for researchers and graduate students who are seeking a comprehensive treatment of the design of instruments and beam-guiding systems of charged particles and their propagation in electromagnetic fields. Wave aspects are included in this edition for explaining electron holography, the Aharanov-Bohm effect and the resolution of electron microscopes limited by diffraction. Several methods for calculating the electromagnetic field are presented and procedures are outlined for calculating the properties of systems with arbitrarily curved axis. Detailed methods are presented for designing and optimizing special components such as aberration correctors, spectrometers, energy filters monochromators, ion traps, electron mirrors and cathode lenses. In particular, the optics of rotationally symmetric lenses, quadrupoles, and systems composed of these elements are...
Phenomenological modeling of Geometric Metasurfaces
Ye, Weimin; Xiang, Yuanjiang; Fan, Dianyuan; Zhang, Shuang
2015-01-01
Metasurfaces, with their superior capability in manipulating the optical wavefront at the subwavelength scale and low manufacturing complexity, have shown great potential for planar photonics and novel optical devices. However, vector field simulation of metasurfaces is so far limited to periodic-structured metasurfaces containing a small number of meta-atoms in the unit cell by using full-wave numerical methods. Here, we propose a general phenomenological method to analytically model metasurfaces made up of arbitrarily distributed meta-atoms based on the assumption that the meta-atoms possess localized resonances with Lorentz-Drude forms, whose exact form can be retrieved from the full wave simulation of a single element. Applied to phase modulated geometric metasurfaces, our analytical results show good agreement with full-wave numerical simulations. The proposed theory provides an efficient method to model and design optical devices based on metasurfaces.
LUNGEOMETRY- GEOMETRICAL INVESTIGATION OF LUNGE
Directory of Open Access Journals (Sweden)
R.Vinodh Rajkumar
2015-02-01
Full Text Available Physiotherapists must learn the biomechanics of lunge in detail to clearly understand its significance in human life and implement effective training measures to overcome the limiting factors of proper lunge of their clientele. To understand the biomechanical value of every movement, interesting experimental learning methods must be employed to kindle the Physiotherapists to actively take part in research activities from the under-graduate level onwards. Lungeometry is a novel, simple and inexpensive experimental investigation of lunge, applying basic geometrical methods taking near normal lower limb length dimensions and rationale approaches into consideration. Lungeometry can give a foundation to learn other forms of lunges like forward lunge, weighted lunges, lateral lunges. This model of learning biomechanics of movements using fundamental geometry techniques is expected to strongly connect with any futuristic Physiotherapy curricular structure.
Geometric interpretation of phyllotaxis transition
Okabe, Takuya
2012-01-01
The original problem of phyllotaxis was focused on the regular arrangements of leaves on mature stems represented by common fractions such as 1/2, 1/3, 2/5, 3/8, 5/13, etc. The phyllotaxis fraction is not fixed for each plant but it may undergo stepwise transitions during ontogeny, despite contrasting observation that the arrangement of leaf primordia at shoot apical meristems changes continuously. No explanation has been given so far for the mechanism of the phyllotaxis transition, excepting suggestion resorting to genetic programs operating at some specific stages. Here it is pointed out that varying length of the leaf trace acts as an important factor to control the transition by analyzing Larson's diagram of the procambial system of young cottonwood plants. The transition is interpreted as a necessary consequence of geometric constraints that the leaf traces cannot be fitted into a fractional pattern unless their length is shorter than the denominator times the internode.
Elastic scattering in geometrical model
Plebaniak, Zbigniew; Wibig, Tadeusz
2016-10-01
The experimental data on proton-proton elastic and inelastic scattering emerging from the measurements at the Large Hadron Collider, calls for an efficient model to fit the data. We have examined the optical, geometrical picture and we have found the simplest, linear dependence of this model parameters on the logarithm of the interaction energy with the significant change of the respective slopes at one point corresponding to the energy of about 300 GeV. The logarithmic dependence observed at high energies allows one to extrapolate the proton-proton elastic, total (and inelastic) cross sections to ultra high energies seen in cosmic rays events which makes a solid justification of the extrapolation to very high energy domain of cosmic rays and could help us to interpret the data from an astrophysical and a high energy physics point of view.
Radio resource management using geometric water-filling
He, Peter; Zhou, Sheng; Niu, Zhisheng
2014-01-01
This brief introduces the fundamental theory and development of managing radio resources using a water-filling algorithm that can optimize system performance in wireless communication. Geometric Water-Filling (GWF) is a crucial underlying tool in emerging communication systems such as multiple input multiple output systems, cognitive radio systems, and green communication systems. Early chapters introduce emerging wireless technologies and provide a detailed analysis of water-filling. The brief investigates single user and multi-user issues of radio resource management, allocation of resources
Kleinberg, Jon
2006-01-01
Algorithm Design introduces algorithms by looking at the real-world problems that motivate them. The book teaches students a range of design and analysis techniques for problems that arise in computing applications. The text encourages an understanding of the algorithm design process and an appreciation of the role of algorithms in the broader field of computer science.
Wang, Lui; Bayer, Steven E.
1991-01-01
Genetic algorithms are mathematical, highly parallel, adaptive search procedures (i.e., problem solving methods) based loosely on the processes of natural genetics and Darwinian survival of the fittest. Basic genetic algorithms concepts are introduced, genetic algorithm applications are introduced, and results are presented from a project to develop a software tool that will enable the widespread use of genetic algorithm technology.
Microlocal Analysis of the Geometric Separation Problem
Donoho, David L
2010-01-01
Image data are often composed of two or more geometrically distinct constituents; in galaxy catalogs, for instance, one sees a mixture of pointlike structures (galaxy superclusters) and curvelike structures (filaments). It would be ideal to process a single image and extract two geometrically `pure' images, each one containing features from only one of the two geometric constituents. This seems to be a seriously underdetermined problem, but recent empirical work achieved highly persuasive separations. We present a theoretical analysis showing that accurate geometric separation of point and curve singularities can be achieved by minimizing the $\\ell_1$ norm of the representing coefficients in two geometrically complementary frames: wavelets and curvelets. Driving our analysis is a specific property of the ideal (but unachievable) representation where each content type is expanded in the frame best adapted to it. This ideal representation has the property that important coefficients are clustered geometrically ...
Geometric solitons of Hamiltonian flows on manifolds
Energy Technology Data Exchange (ETDEWEB)
Song, Chong, E-mail: songchong@xmu.edu.cn [School of Mathematical Sciences, Xiamen University, Xiamen 361005 (China); Sun, Xiaowei, E-mail: sunxw@cufe.edu.cn [School of Applied Mathematics, Central University of Finance and Economics, Beijing 100081 (China); Wang, Youde, E-mail: wyd@math.ac.cn [Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China)
2013-12-15
It is well-known that the LIE (Locally Induction Equation) admit soliton-type solutions and same soliton solutions arise from different and apparently irrelevant physical models. By comparing the solitons of LIE and Killing magnetic geodesics, we observe that these solitons are essentially decided by two families of isometries of the domain and the target space, respectively. With this insight, we propose the new concept of geometric solitons of Hamiltonian flows on manifolds, such as geometric Schrödinger flows and KdV flows for maps. Moreover, we give several examples of geometric solitons of the Schrödinger flow and geometric KdV flow, including magnetic curves as geometric Schrödinger solitons and explicit geometric KdV solitons on surfaces of revolution.
Directory of Open Access Journals (Sweden)
Bum-Joo Lee
2013-02-01
Full Text Available In this paper differential kinematics was geometrically derived to be utilized in a calibration algorithm that improves the accuracy of the manipulation of a robot. Even though the mechanical components are manufactured and assembled precisely, small differences between the designed and the actual system always exist, due to both geometric and unmodelled errors. In order to resolve these problems, differential relationships between the model parameters and the end‐effectorʹs posture were formulated. Subsequently, a derivative based estimation algorithm, such as an EKF (Extended Kalman Filter manner, could be adopted to update the model parameters. The proposed algorithm includes joint flexibility, so is an advanced version of previous work, where a rigid joint model was adopted [1]. The effectiveness of the proposed algorithm was verified by a computer simulation with a 6 DOF manipulator robot.
Directory of Open Access Journals (Sweden)
Bum-Joo Lee
2013-02-01
Full Text Available In this paper differential kinematics was geometrically derived to be utilized in a calibration algorithm that improves the accuracy of the manipulation of a robot. Even though the mechanical components are manufactured and assembled precisely, small differences between the designed and the actual system always exist, due to both geometric and unmodelled errors. In order to resolve these problems, differential relationships between the model parameters and the end-effector's posture were formulated. Subsequently, a derivative based estimation algorithm, such as an EKF (Extended Kalman Filter manner, could be adopted to update the model parameters. The proposed algorithm includes joint flexibility, so is an advanced version of previous work, where a rigid joint model was adopted [1]. The effectiveness of the proposed algorithm was verified by a computer simulation with a 6 DOF manipulator robot.
A Parallel Butterfly Algorithm
Poulson, Jack
2014-02-04
The butterfly algorithm is a fast algorithm which approximately evaluates a discrete analogue of the integral transform (Equation Presented.) at large numbers of target points when the kernel, K(x, y), is approximately low-rank when restricted to subdomains satisfying a certain simple geometric condition. In d dimensions with O(Nd) quasi-uniformly distributed source and target points, when each appropriate submatrix of K is approximately rank-r, the running time of the algorithm is at most O(r2Nd logN). A parallelization of the butterfly algorithm is introduced which, assuming a message latency of α and per-process inverse bandwidth of β, executes in at most (Equation Presented.) time using p processes. This parallel algorithm was then instantiated in the form of the open-source DistButterfly library for the special case where K(x, y) = exp(iΦ(x, y)), where Φ(x, y) is a black-box, sufficiently smooth, real-valued phase function. Experiments on Blue Gene/Q demonstrate impressive strong-scaling results for important classes of phase functions. Using quasi-uniform sources, hyperbolic Radon transforms, and an analogue of a three-dimensional generalized Radon transform were, respectively, observed to strong-scale from 1-node/16-cores up to 1024-nodes/16,384-cores with greater than 90% and 82% efficiency, respectively. © 2014 Society for Industrial and Applied Mathematics.
Institute of Scientific and Technical Information of China (English)
马利民; 王金星; 蒋向前; 李柱; 徐振高
2004-01-01
Geometrical Product Specification and verification (GPS) is an ISO standard system coveting standards of size, dimension,geometrical tolerance and surface texture of geometrical product. ISO/TC213 on the GPS has been working towards coordination of the previous standards in tolerance and related metrology in order to publish the next generation of the GPS language. This paper introduces the geometrical product specification model for design, manufacturing and verification based on the improved GPS and its new concepts,i.e., surface models, geometrical features and operations. An application example for the geometrical product specification model is then given.
Geometric Photonic Spin Hall Effect with Metapolarization
2014-01-01
We develop a geometric photonic spin Hall effect (PSHE) which manifests as spin-dependent shift in momentum space. It originates from an effective space-variant Pancharatnam-Berry (PB) phase created by artificially engineering the polarization distribution of the incident light. Unlikely the previously reported PSHE involving the light-matter interaction, the resulting spin-dependent splitting in the geometric PSHE is purely geometrically depend upon the polarization distribution of light whi...
A Geometric Approach to Noncommutative Principal Bundles
Wagner, Stefan
2011-01-01
From a geometrical point of view it is, so far, not sufficiently well understood what should be a "noncommutative principal bundle". Still, there is a well-developed abstract algebraic approach using the theory of Hopf algebras. An important handicap of this approach is the ignorance of topological and geometrical aspects. The aim of this thesis is to develop a geometrically oriented approach to the noncommutative geometry of principal bundles based on dynamical systems and the representation theory of the corresponding transformation group.
Guide to Geometric Algebra in Practice
Dorst, Leo
2011-01-01
This highly practical "Guide to Geometric Algebra in Practice" reviews algebraic techniques for geometrical problems in computer science and engineering, and the relationships between them. The topics covered range from powerful new theoretical developments, to successful applications, and the development of new software and hardware tools. This title: provides hands-on review exercises throughout the book, together with helpful chapter summaries; presents a concise introductory tutorial to conformal geometric algebra (CGA) in the appendices; examines the application of CGA for the d
Geometrical and computer modeling of mechanical engineering surfaces products intersection line
Panchuk, K. L.; Kaygorodtseva, N. V.; Kaygorodtseva, T. N.; Yurkov, V. Yu
2017-06-01
In the design and manufacture of engineering products geometrical problem is known by shaping the surface of the product. An important element of general solution of this problem is to define the lines of surfaces intersection, forming the shape of designed product. Existing possibilities of modern CAD systems do not allow achieving fullness of the result in this direction. For example, control points and change point of visibility is difficult to identify in the product drawings. In addition, there are no possibilities of detecting imaginary points which are necessary for a complete analysis of intersection surfaces, and mapping these points in the drawing. The aim of the study is to develop a geometric algorithm of constructive determining the intersection line and is devoid of these shortcomings. The objectives of the study are testing the obtained algorithm by experimental verification with geometric modeling solutions to specific problems by tools CAD. This study adopted the method, which is based on quotient of geometric sets, which are regarded as intersecting surfaces in space E3 . One area of practical use of surface engineering products geometric algorithm - shaping is based on their intersection line.
Report on Workshop on Geometric Scattering
DEFF Research Database (Denmark)
As part of the activities of MaPhySto a workshop on geometric scattering was organized at University of Aarhus, November 5-7, 1998. The workshop was narrowly focused on geometric scattering, and in particular the use of geometric scattering in understanding the structure of the scattering operator...... for the quantum mechanical many-body problem. A number of other questions were also discussed in detail, including the resonances and various geometric questions. This report includes the program of the workshop, a collection of previews, abstracts, and reports on the lectures, with extensive references....
Higher-Dimensional Geometric $\\sigma$-Models
Vasilic, M
1999-01-01
Geometric $\\sigma$-models have been defined as purely geometric theories of scalar fields coupled to gravity. By construction, these theories possess arbitrarily chosen vacuum solutions. Using this fact, one can build a Kaluza--Klein geometric $\\sigma$-model by specifying the vacuum metric of the form $M^4\\times B^d$. The obtained higher dimensional theory has vanishing cosmological constant but fails to give massless gauge fields after the dimensional reduction. In this paper, a modified geometric $\\sigma$-model is suggested, which solves the above problem.
Adiabatic geometric phases in hydrogenlike atoms
Sjöqvist, Erik; Yi, X. X.; Åberg, Johan
2005-11-01
We examine the effect of spin-orbit coupling on geometric phases in hydrogenlike atoms exposed to a slowly varying magnetic field. The marginal geometric phases associated with the orbital angular momentum and the intrinsic spin fulfill a sum rule that explicitly relates them to the corresponding geometric phase of the whole system. The marginal geometric phases in the Zeeman and Paschen-Back limits are analyzed. We point out the existence of nodal points in the marginal phases that may be detected by topological means.
Adiabatic geometric phases in hydrogenlike atoms
Sjöqvist, E; Sj\\"{o}qvist, Erik
2005-01-01
We examine the effect of spin-orbit coupling on geometric phases in hydrogenlike atoms exposed to a slowly varying magnetic field. The marginal geometric phases associated with the orbital angular momentum and the intrinsic spin fulfill a sum rule that explicitly relates them to the corresponding geometric phase of the whole system. The marginal geometric phases in the Zeeman and Paschen-Back limit are analyzed. We point out the existence of nodal points in the marginal phases that may be detected by topological means.
Geometric properties for incomplete data
Weickert, Joachim
2006-01-01
Comprehensive treatment of approximation or interpolation subjects in the context of image analysis (or data analysis in general)First-time book bringing discrete and continuous geometry together to these subjectsA balanced presentation of fundamental and applied work, supporting practioners in understanding theoretical concepts, and theorists in understanding potential applicationsPresentation of new research results in approximation theory, and discrete or continuous geometry within the general orientation of the bookInteresting connections to computational or algorithmic geometry
Digital and discrete geometry theory and algorithms
Chen, Li
2014-01-01
This book provides comprehensive coverage of the modern methods for geometric problems in the computing sciences. It also covers concurrent topics in data sciences including geometric processing, manifold learning, Google search, cloud data, and R-tree for wireless networks and BigData.The author investigates digital geometry and its related constructive methods in discrete geometry, offering detailed methods and algorithms. The book is divided into five sections: basic geometry; digital curves, surfaces and manifolds; discretely represented objects; geometric computation and processing; and a
Institute of Scientific and Technical Information of China (English)
张秋娥
2011-01-01
在高等院校竞争愈演愈烈的严峻形势下,＂建设教学研究型二级学院＂是我校领导当下审时度势作出的科学决策。高职称、高学历教师应该在建设教学研究型二级学院中有大作为。%＂Building up a second-grade collage of teaching and researching＂ is a decision of strategic importance made by our collage leader when the competition among the institutes of higher learning in china is becoming fiercer nowdays.Teachers with higher professional titles and academic qualifications should play important roles in the campaign.
SYMBOLIC VERSOR COMPRESSION ALGORITHM
Institute of Scientific and Technical Information of China (English)
Li Hongbo
2009-01-01
In an inner-product space, an invertible vector generates a reflection with re-spect to a hyperplane, and the Clifford product of several invertible vectors, called a versor in Clifford algebra, generates the composition of the corresponding reflections, which is an orthogonal transformation. Given a versor in a Clifford algebra, finding another sequence of invertible vectors of strictly shorter length but whose Clifford product still equals the input versor, is called versor compression. Geometrically, versor compression is equivalent to decomposing an orthogoual transformation into a shorter sequence of reflections. This paper proposes a simple algorithm of compressing versors of symbolic form in Clifford algebra. The algorithm is based on computing the intersections of lines with planes in the corresponding Grassmann-Cayley algebra, and is complete in the case of Euclidean or Minkowski inner-product space.
DOA Estimation of Cylindrical Conformal Array Based on Geometric Algebra
Directory of Open Access Journals (Sweden)
Minjie Wu
2016-01-01
Full Text Available Due to the variable curvature of the conformal carrier, the pattern of each element has a different direction. The traditional method of analyzing the conformal array is to use the Euler rotation angle and its matrix representation. However, it is computationally demanding especially for irregular array structures. In this paper, we present a novel algorithm by combining the geometric algebra with Multiple Signal Classification (MUSIC, termed as GA-MUSIC, to solve the direction of arrival (DOA for cylindrical conformal array. And on this basis, we derive the pattern and array manifold. Compared with the existing algorithms, our proposed one avoids the cumbersome matrix transformations and largely decreases the computational complexity. The simulation results verify the effectiveness of the proposed method.
Discrete geometric structures for architecture
Pottmann, Helmut
2010-06-13
The emergence of freeform structures in contemporary architecture raises numerous challenging research problems, most of which are related to the actual fabrication and are a rich source of research topics in geometry and geometric computing. The talk will provide an overview of recent progress in this field, with a particular focus on discrete geometric structures. Most of these result from practical requirements on segmenting a freeform shape into planar panels and on the physical realization of supporting beams and nodes. A study of quadrilateral meshes with planar faces reveals beautiful relations to discrete differential geometry. In particular, we discuss meshes which discretize the network of principal curvature lines. Conical meshes are among these meshes; they possess conical offset meshes at a constant face/face distance, which in turn leads to a supporting beam layout with so-called torsion free nodes. This work can be generalized to a variety of multilayer structures and laid the ground for an adapted curvature theory for these meshes. There are also efforts on segmenting surfaces into planar hexagonal panels. Though these are less constrained than planar quadrilateral panels, this problem is still waiting for an elegant solution. Inspired by freeform designs in architecture which involve circles and spheres, we present a new kind of triangle mesh whose faces\\' in-circles form a packing, i.e., the in-circles of two triangles with a common edge have the same contact point on that edge. These "circle packing (CP) meshes" exhibit an aesthetic balance of shape and size of their faces. They are closely tied to sphere packings on surfaces and to various remarkable structures and patterns which are of interest in art, architecture, and design. CP meshes constitute a new link between architectural freeform design and computational conformal geometry. Recently, certain timber structures motivated us to study discrete patterns of geodesics on surfaces. This
An Optimized Method for PDEs-Based Geometric Modeling and Reconstruction
Directory of Open Access Journals (Sweden)
Chuanjun Wang
2012-09-01
Full Text Available This study presents an optimized method for efficient geometric modeling and reconstruction using Partial Differential Equations (PDEs. Based on the identification between the analytic solution of Bloor Wilson PDE and the Fourier series, we transform the problem of model selection for PDEs-based geometric modeling into the problem of significant frequencies selection from Fourier series. With the significance analysis of the Fourier series, a model selection and an iterative surface fitting algorithm are applied to address the problem of overfitting and underfitting in the PDEs-based geometric modeling and reconstruction. Simulations are conducted on both the computer generated geometric surface and the laser scanned 3D face data. Experiment results show the merits of the proposed method.
Improvement of nonlinear diffusion equation using relaxed geometric mean filter for low PSNR images
DEFF Research Database (Denmark)
Nadernejad, Ehsan
2013-01-01
A new method to improve the performance of low PSNR image denoising is presented. The proposed scheme estimates edge gradient from an image that is regularised with a relaxed geometric mean filter. The proposed method consists of two stages; the first stage consists of a second order nonlinear...... anisotropic diffusion equation with new neighboring structure and the second is a relaxed geometric mean filter, which processes the output of nonlinear anisotropic diffusion equation. The proposed algorithm enjoys the benefit of both nonlinear PDE and relaxed geometric mean filter. In addition, the algorithm...... will not introduce any artefacts, and preserves image details, sharp corners, curved structures and thin lines. Comparison of the results obtained by the proposed method, with those of other methods, shows that a noticeable improvement in the quality of the denoised images, that were evaluated subjectively...
Institute of Scientific and Technical Information of China (English)
LI Zhanli; SUN Xiuying
2006-01-01
VRML(Virtual Reality Modeling Language) format as an international standard for virtual reality, has already been widely adopted for graphical representation of 3D objects over the Web. Adopting VRML model in RP(Rapid Prototyping) can reduce the precision loss which is caused by triangulation in generating STL file. Hence exploring a slicing method and developing a slicing software for VRML model is important and significant to improve the accuracy of RP products. Finding intersections of a plane and VRML model is the key operation in slicing algorithm. This paper presents a method for calculating the intersections between a set of parallel planes and VRML geometric primitives. Based on the analysis of the relative position between a plane and a geometric primitive, intersection conditions in all cases were obtained, and the geometric parameters and corresponding equations of intersections were derived. The algorithm had been tested, and applications show that it is robust and effective.
Geometric Modeling and Reasoning of Human-Centered Freeform Products
Wang, Charlie C L
2013-01-01
The recent trend in user-customized product design requires the shape of products to be automatically adjusted according to the human body’s shape, so that people will feel more comfortable when wearing these products. Geometric approaches can be used to design the freeform shape of products worn by people, which can greatly improve the efficiency of design processes in various industries involving customized products (e.g., garment design, toy design, jewel design, shoe design, and design of medical devices, etc.). These products are usually composed of very complex geometric shapes (represented by free-form surfaces), and are not driven by a parameter table but a digital human model with free-form shapes or part of human bodies (e.g., wrist, foot, and head models). Geometric Modeling and Reasoning of Human-Centered Freeform Products introduces the algorithms of human body reconstruction, freeform product modeling, constraining and reconstructing freeform products, and shape optimization for improving...
Fractal supersymmetric QM, Geometric Probability and the Riemann Hypothesis
Castro, C
2004-01-01
The Riemann's hypothesis (RH) states that the nontrivial zeros of the Riemann zeta-function are of the form $ s_n =1/2+i\\lambda_n $. Earlier work on the RH based on supersymmetric QM, whose potential was related to the Gauss-Jacobi theta series, allows to provide the proper framework to construct the well defined algorithm to compute the probability to find a zero (an infinity of zeros) in the critical line. Geometric probability theory furnishes the answer to the very difficult question whether the probability that the RH is true is indeed equal to unity or not. To test the validity of this geometric probabilistic framework to compute the probability if the RH is true, we apply it directly to the the hyperbolic sine function $ \\sinh (s) $ case which obeys a trivial analog of the RH (the HSRH). Its zeros are equally spaced in the imaginary axis $ s_n = 0 + i n \\pi $. The geometric probability to find a zero (and an infinity of zeros) in the imaginary axis is exactly unity. We proceed with a fractal supersymme...
Approximate joint diagonalization and geometric mean of symmetric positive definite matrices.
Congedo, Marco; Afsari, Bijan; Barachant, Alexandre; Moakher, Maher
2014-01-01
We explore the connection between two problems that have arisen independently in the signal processing and related fields: the estimation of the geometric mean of a set of symmetric positive definite (SPD) matrices and their approximate joint diagonalization (AJD). Today there is a considerable interest in estimating the geometric mean of a SPD matrix set in the manifold of SPD matrices endowed with the Fisher information metric. The resulting mean has several important invariance properties and has proven very useful in diverse engineering applications such as biomedical and image data processing. While for two SPD matrices the mean has an algebraic closed form solution, for a set of more than two SPD matrices it can only be estimated by iterative algorithms. However, none of the existing iterative algorithms feature at the same time fast convergence, low computational complexity per iteration and guarantee of convergence. For this reason, recently other definitions of geometric mean based on symmetric divergence measures, such as the Bhattacharyya divergence, have been considered. The resulting means, although possibly useful in practice, do not satisfy all desirable invariance properties. In this paper we consider geometric means of covariance matrices estimated on high-dimensional time-series, assuming that the data is generated according to an instantaneous mixing model, which is very common in signal processing. We show that in these circumstances we can approximate the Fisher information geometric mean by employing an efficient AJD algorithm. Our approximation is in general much closer to the Fisher information geometric mean as compared to its competitors and verifies many invariance properties. Furthermore, convergence is guaranteed, the computational complexity is low and the convergence rate is quadratic. The accuracy of this new geometric mean approximation is demonstrated by means of simulations.
Approximate Joint Diagonalization and Geometric Mean of Symmetric Positive Definite Matrices
Congedo, Marco; Afsari, Bijan; Barachant, Alexandre; Moakher, Maher
2015-01-01
We explore the connection between two problems that have arisen independently in the signal processing and related fields: the estimation of the geometric mean of a set of symmetric positive definite (SPD) matrices and their approximate joint diagonalization (AJD). Today there is a considerable interest in estimating the geometric mean of a SPD matrix set in the manifold of SPD matrices endowed with the Fisher information metric. The resulting mean has several important invariance properties and has proven very useful in diverse engineering applications such as biomedical and image data processing. While for two SPD matrices the mean has an algebraic closed form solution, for a set of more than two SPD matrices it can only be estimated by iterative algorithms. However, none of the existing iterative algorithms feature at the same time fast convergence, low computational complexity per iteration and guarantee of convergence. For this reason, recently other definitions of geometric mean based on symmetric divergence measures, such as the Bhattacharyya divergence, have been considered. The resulting means, although possibly useful in practice, do not satisfy all desirable invariance properties. In this paper we consider geometric means of covariance matrices estimated on high-dimensional time-series, assuming that the data is generated according to an instantaneous mixing model, which is very common in signal processing. We show that in these circumstances we can approximate the Fisher information geometric mean by employing an efficient AJD algorithm. Our approximation is in general much closer to the Fisher information geometric mean as compared to its competitors and verifies many invariance properties. Furthermore, convergence is guaranteed, the computational complexity is low and the convergence rate is quadratic. The accuracy of this new geometric mean approximation is demonstrated by means of simulations. PMID:25919667
Joux, Antoine
2009-01-01
Illustrating the power of algorithms, Algorithmic Cryptanalysis describes algorithmic methods with cryptographically relevant examples. Focusing on both private- and public-key cryptographic algorithms, it presents each algorithm either as a textual description, in pseudo-code, or in a C code program.Divided into three parts, the book begins with a short introduction to cryptography and a background chapter on elementary number theory and algebra. It then moves on to algorithms, with each chapter in this section dedicated to a single topic and often illustrated with simple cryptographic applic
Geometric reasoning about assembly tools
Energy Technology Data Exchange (ETDEWEB)
Wilson, R.H.
1997-01-01
Planning for assembly requires reasoning about various tools used by humans, robots, or other automation to manipulate, attach, and test parts and subassemblies. This paper presents a general framework to represent and reason about geometric accessibility issues for a wide variety of such assembly tools. Central to the framework is a use volume encoding a minimum space that must be free in an assembly state to apply a given tool, and placement constraints on where that volume must be placed relative to the parts on which the tool acts. Determining whether a tool can be applied in a given assembly state is then reduced to an instance of the FINDPLACE problem. In addition, the author presents more efficient methods to integrate the framework into assembly planning. For tools that are applied either before or after their target parts are mated, one method pre-processes a single tool application for all possible states of assembly of a product in polynomial time, reducing all later state-tool queries to evaluations of a simple expression. For tools applied after their target parts are mated, a complementary method guarantees polynomial-time assembly planning. The author presents a wide variety of tools that can be described adequately using the approach, and surveys tool catalogs to determine coverage of standard tools. Finally, the author describes an implementation of the approach in an assembly planning system and experiments with a library of over one hundred manual and robotic tools and several complex assemblies.
Generalized Geometric Quantum Speed Limits
Pires, Diego Paiva; Cianciaruso, Marco; Céleri, Lucas C.; Adesso, Gerardo; Soares-Pinto, Diogo O.
2016-04-01
The attempt to gain a theoretical understanding of the concept of time in quantum mechanics has triggered significant progress towards the search for faster and more efficient quantum technologies. One of such advances consists in the interpretation of the time-energy uncertainty relations as lower bounds for the minimal evolution time between two distinguishable states of a quantum system, also known as quantum speed limits. We investigate how the nonuniqueness of a bona fide measure of distinguishability defined on the quantum-state space affects the quantum speed limits and can be exploited in order to derive improved bounds. Specifically, we establish an infinite family of quantum speed limits valid for unitary and nonunitary evolutions, based on an elegant information geometric formalism. Our work unifies and generalizes existing results on quantum speed limits and provides instances of novel bounds that are tighter than any established one based on the conventional quantum Fisher information. We illustrate our findings with relevant examples, demonstrating the importance of choosing different information metrics for open system dynamics, as well as clarifying the roles of classical populations versus quantum coherences, in the determination and saturation of the speed limits. Our results can find applications in the optimization and control of quantum technologies such as quantum computation and metrology, and might provide new insights in fundamental investigations of quantum thermodynamics.
Geometric Reasoning for Automated Planning
Clement, Bradley J.; Knight, Russell L.; Broderick, Daniel
2012-01-01
An important aspect of mission planning for NASA s operation of the International Space Station is the allocation and management of space for supplies and equipment. The Stowage, Configuration Analysis, and Operations Planning teams collaborate to perform the bulk of that planning. A Geometric Reasoning Engine is developed in a way that can be shared by the teams to optimize item placement in the context of crew planning. The ISS crew spends (at the time of this writing) a third or more of their time moving supplies and equipment around. Better logistical support and optimized packing could make a significant impact on operational efficiency of the ISS. Currently, computational geometry and motion planning do not focus specifically on the optimized orientation and placement of 3D objects based on multiple distance and containment preferences and constraints. The software performs reasoning about the manipulation of 3D solid models in order to maximize an objective function based on distance. It optimizes for 3D orientation and placement. Spatial placement optimization is a general problem and can be applied to object packing or asset relocation.
Generalized Geometric Quantum Speed Limits
Directory of Open Access Journals (Sweden)
Diego Paiva Pires
2016-06-01
Full Text Available The attempt to gain a theoretical understanding of the concept of time in quantum mechanics has triggered significant progress towards the search for faster and more efficient quantum technologies. One of such advances consists in the interpretation of the time-energy uncertainty relations as lower bounds for the minimal evolution time between two distinguishable states of a quantum system, also known as quantum speed limits. We investigate how the nonuniqueness of a bona fide measure of distinguishability defined on the quantum-state space affects the quantum speed limits and can be exploited in order to derive improved bounds. Specifically, we establish an infinite family of quantum speed limits valid for unitary and nonunitary evolutions, based on an elegant information geometric formalism. Our work unifies and generalizes existing results on quantum speed limits and provides instances of novel bounds that are tighter than any established one based on the conventional quantum Fisher information. We illustrate our findings with relevant examples, demonstrating the importance of choosing different information metrics for open system dynamics, as well as clarifying the roles of classical populations versus quantum coherences, in the determination and saturation of the speed limits. Our results can find applications in the optimization and control of quantum technologies such as quantum computation and metrology, and might provide new insights in fundamental investigations of quantum thermodynamics.
Geometrical aspects of quantum spaces
Energy Technology Data Exchange (ETDEWEB)
Ho, P.M. [Lawrence Berkeley Lab., CA (United States). Theoretical Physics Group
1996-05-11
Various geometrical aspects of quantum spaces are presented showing the possibility of building physics on quantum spaces. In the first chapter the authors give the motivations for studying noncommutative geometry and also review the definition of a Hopf algebra and some general features of the differential geometry on quantum groups and quantum planes. In Chapter 2 and Chapter 3 the noncommutative version of differential calculus, integration and complex structure are established for the quantum sphere S{sub 1}{sup 2} and the quantum complex projective space CP{sub q}(N), on which there are quantum group symmetries that are represented nonlinearly, and are respected by all the aforementioned structures. The braiding of S{sub q}{sup 2} and CP{sub q}(N) is also described. In Chapter 4 the quantum projective geometry over the quantum projective space CP{sub q}(N) is developed. Collinearity conditions, coplanarity conditions, intersections and anharmonic ratios is described. In Chapter 5 an algebraic formulation of Reimannian geometry on quantum spaces is presented where Riemannian metric, distance, Laplacian, connection, and curvature have their quantum counterparts. This attempt is also extended to complex manifolds. Examples include the quantum sphere, the complex quantum projective space and the two-sheeted space. The quantum group of general coordinate transformations on some quantum spaces is also given.
Geometric calibration of multi-sensor image fusion system with thermal infrared and low-light camera
Peric, Dragana; Lukic, Vojislav; Spanovic, Milana; Sekulic, Radmila; Kocic, Jelena
2014-10-01
A calibration platform for geometric calibration of multi-sensor image fusion system is presented in this paper. The accurate geometric calibration of the extrinsic geometric parameters of cameras that uses planar calibration pattern is applied. For calibration procedure specific software is made. Patterns used in geometric calibration are prepared with aim to obtain maximum contrast in both visible and infrared spectral range - using chessboards which fields are made of different emissivity materials. Experiments were held in both indoor and outdoor scenarios. Important results of geometric calibration for multi-sensor image fusion system are extrinsic parameters in form of homography matrices used for homography transformation of the object plane to the image plane. For each camera a corresponding homography matrix is calculated. These matrices can be used for image registration of images from thermal and low light camera. We implemented such image registration algorithm to confirm accuracy of geometric calibration procedure in multi-sensor image fusion system. Results are given for selected patterns - chessboard with fields made of different emissivity materials. For the final image registration algorithm in surveillance system for object tracking we have chosen multi-resolution image registration algorithm which naturally combines with a pyramidal fusion scheme. The image pyramids which are generated at each time step of image registration algorithm may be reused at the fusion stage so that overall number of calculations that must be performed is greatly reduced.
Feel Beijing and build up friendship
Institute of Scientific and Technical Information of China (English)
Chang; Jiuqing
2005-01-01
Though it was April, spring was coming, the chill still lingered in the capital city. Invited by the Chinese Association for International Understanding（CAFIU）, a group of three Americans from the Mississippi State of the U.S. with Mr. Garrott as the head visited Beijing from April 4 to 9.
Geometrical splitting and reduction of Feynman diagrams
Davydychev, Andrei I.
2016-10-01
A geometrical approach to the calculation of N-point Feynman diagrams is reviewed. It is shown that the geometrical splitting yields useful connections between Feynman integrals with different momenta and masses. It is demonstrated how these results can be used to reduce the number of variables in the occurring functions.
Parabolas: Connection between Algebraic and Geometrical Representations
Shriki, Atara
2011-01-01
A parabola is an interesting curve. What makes it interesting at the secondary school level is the fact that this curve is presented in both its contexts: algebraic and geometric. Being one of Apollonius' conic sections, the parabola is basically a geometric entity. It is, however, typically known for its algebraic characteristics, in particular…
Some technical issues in geometric modeling
Energy Technology Data Exchange (ETDEWEB)
Peterson, D.P.
1983-01-01
The full impact of CAD/CAM will not be felt until geometric modeling systems support dimensioning and tolerancing, have sophisticated user interfaces, and are capable of routinely handling many representation conversions. The attainment of these capabilities requires a joint effort among users, implementors, and theoreticians of geometric modeling.
Geometric Growing Patterns: What's the Rule?
Hourigan, Mairéad; Leavy, Aisling
2015-01-01
While within a geometric repeating pattern, there is an identifiable core which is made up of objects that repeat in a predictable manner, a geometric growing pattern (also called visual or pictorial growing patterns in other curricula) "is a pattern that is made from a sequence of figures [or objects] that change from one term to the next in…
Sudan-decoding generalized geometric Goppa codes
DEFF Research Database (Denmark)
Heydtmann, Agnes Eileen
2003-01-01
Generalized geometric Goppa codes are vector spaces of n-tuples with entries from different extension fields of a ground field. They are derived from evaluating functions similar to conventional geometric Goppa codes, but allowing evaluation in places of arbitrary degree. A decoding scheme...
A Framework for Analyzing Geometric Pattern Tasks
Friel, Susan N.; Markworth, Kimberly A.
2009-01-01
Teachers can use geometric patterns to promote students' understanding of functional relationships. In this article, the authors first look at a problem-solving process that supports the use of figural reasoning to explore and interpret geometric pattern tasks and generalize function rules. Second, the authors discuss a framework for…
On geometric Langlands theory and stacks
Poirier, Cécile Florence Christine
2008-01-01
R.Langlands conjectured the existence of a bridge between two parts of number theory. This correspondence, called 'Langlands conjecture' was proved by L. Lafforgue who obtained a Fields medal for his work. G. Laumon gave a geometric translation of a part of the theorem, called 'geometric Langlands c
Geometrical optics and the diffraction phenomenon
Energy Technology Data Exchange (ETDEWEB)
Timofeev, Aleksandr V [Russian Research Centre ' Kurchatov Institute' , Moscow (Russian Federation)
2005-06-30
This note outlines the principles of the geometrical optics of inhomogeneous waves whose description necessitates the use of complex values of the wave vector. Generalizing geometrical optics to inhomogeneous waves permits including in its scope the analysis of the diffraction phenomenon. (methodological notes)
Variance optimal stopping for geometric Levy processes
DEFF Research Database (Denmark)
Gad, Kamille Sofie Tågholt; Pedersen, Jesper Lund
2015-01-01
The main result of this paper is the solution to the optimal stopping problem of maximizing the variance of a geometric Lévy process. We call this problem the variance problem. We show that, for some geometric Lévy processes, we achieve higher variances by allowing randomized stopping. Furthermore...
Geometrical description of denormalized thermodynamic manifold
Institute of Scientific and Technical Information of China (English)
Wu Li-Ping; Sun Hua-Fei; Cao Li-Mei
2009-01-01
In view of differential geometry,the state space of thermodynamic parameters is investigated. Here the geometrical structures of the denormalized thermodynamic manifold are considered. The relation of their geometrical metrics is obtained. Moreover an example is used to illustrate our conclusions.
The geometric semantics of algebraic quantum mechanics.
Cruz Morales, John Alexander; Zilber, Boris
2015-08-06
In this paper, we will present an ongoing project that aims to use model theory as a suitable mathematical setting for studying the formalism of quantum mechanics. We argue that this approach provides a geometric semantics for such a formalism by means of establishing a (non-commutative) duality between certain algebraic and geometric objects.
Geometric phases in discrete dynamical systems
Energy Technology Data Exchange (ETDEWEB)
Cartwright, Julyan H.E., E-mail: julyan.cartwright@csic.es [Instituto Andaluz de Ciencias de la Tierra, CSIC–Universidad de Granada, E-18100 Armilla, Granada (Spain); Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, E-18071 Granada (Spain); Piro, Nicolas, E-mail: nicolas.piro@epfl.ch [École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne (Switzerland); Piro, Oreste, E-mail: piro@imedea.uib-csic.es [Departamento de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Tuval, Idan, E-mail: ituval@imedea.uib-csic.es [Mediterranean Institute for Advanced Studies, CSIC–Universitat de les Illes Balears, E-07190 Mallorca (Spain)
2016-10-14
In order to study the behaviour of discrete dynamical systems under adiabatic cyclic variations of their parameters, we consider discrete versions of adiabatically-rotated rotators. Parallelling the studies in continuous systems, we generalize the concept of geometric phase to discrete dynamics and investigate its presence in these rotators. For the rotated sine circle map, we demonstrate an analytical relationship between the geometric phase and the rotation number of the system. For the discrete version of the rotated rotator considered by Berry, the rotated standard map, we further explore this connection as well as the role of the geometric phase at the onset of chaos. Further into the chaotic regime, we show that the geometric phase is also related to the diffusive behaviour of the dynamical variables and the Lyapunov exponent. - Highlights: • We extend the concept of geometric phase to maps. • For the rotated sine circle map, we demonstrate an analytical relationship between the geometric phase and the rotation number. • For the rotated standard map, we explore the role of the geometric phase at the onset of chaos. • We show that the geometric phase is related to the diffusive behaviour of the dynamical variables and the Lyapunov exponent.
Geometric integrators for stochastic rigid body dynamics
Tretyakov, Mikhail
2016-01-05
Geometric integrators play an important role in simulating dynamical systems on long time intervals with high accuracy. We will illustrate geometric integration ideas within the stochastic context, mostly on examples of stochastic thermostats for rigid body dynamics. The talk will be mainly based on joint recent work with Rusland Davidchak and Tom Ouldridge.
Geometric Computations On Indecisive Points
DEFF Research Database (Denmark)
Jørgensen, Allan Grønlund; Phillips, Jeff; Loffler, Maarten
2011-01-01
We study computing with indecisive point sets. Such points have spatial uncertainty where the true location is one of a finite number of possible locations. This data arises from probing distributions a few times or when the location is one of a few locations from a known database. In particular......-hard. We generalize our polynomial-time algorithm to all LP-type problems. We also utilize our indecisive framework to deterministically and approximately compute on a more general class of uncertain data where the location of each point is given by a probability distribution....
Kernel Projection Algorithm for Large-Scale SVM Problems
Institute of Scientific and Technical Information of China (English)
王家琦; 陶卿; 王珏
2002-01-01
Support Vector Machine (SVM) has become a very effective method in sta-tistical machine learning and it has proved that training SVM is to solve Nearest Point pairProblem (NPP) between two disjoint closed convex sets. Later Keerthi pointed out that it isdifficult to apply classical excellent geometric algorithms directly to SVM and so designed anew geometric algorithm for SVM. In this article, a new algorithm for geometrically solvingSVM, Kernel Projection Algorithm, is presented based on the theorem on fixed-points of pro-jection mapping. This new algorithm makes it easy to apply classical geometric algorithmsto solving SVM and is more understandable than Keerthi's. Experiments show that the newalgorithm can also handle large-scale SVM problems. Geometric algorithms for SVM, such asKeerthi's algorithm, require that two closed convex sets be disjoint and otherwise the algo-rithms are meaningless. In this article, this requirement will be guaranteed in theory by usingthe theoretic result on universal kernel functions.
High-fidelity geometric modeling for biomedical applications
Energy Technology Data Exchange (ETDEWEB)
Yu, Zeyun [Univ. of California, San Diego, CA (United States). Dept. of Mathematics; Holst, Michael J. [Univ. of California, San Diego, CA (United States). Dept. of Mathematics; Andrew McCammon, J. [Univ. of California, San Diego, CA (United States). Dept. of Chemistry and Biochemistry; Univ. of California, San Diego, CA (United States). Dept. of Pharmacology
2008-05-19
In this paper, we describe a combination of algorithms for high-fidelity geometric modeling and mesh generation. Although our methods and implementations are application-neutral, our primary target application is multiscale biomedical models that range in scales across the molecular, cellular, and organ levels. Our software toolchain implementing these algorithms is general in the sense that it can take as input a molecule in PDB/PQR forms, a 3D scalar volume, or a user-defined triangular surface mesh that may have very low quality. The main goal of our work presented is to generate high quality and smooth surface triangulations from the aforementioned inputs, and to reduce the mesh sizes by mesh coarsening. Tetrahedral meshes are also generated for finite element analysis in biomedical applications. Experiments on a number of bio-structures are demonstrated, showing that our approach possesses several desirable properties: feature-preservation, local adaptivity, high quality, and smoothness (for surface meshes). Finally, the availability of this software toolchain will give researchers in computational biomedicine and other modeling areas access to higher-fidelity geometric models.
Geometric Control of Patterned Linear Systems
Hamilton, Sarah C
2012-01-01
This monograph is aiming at researchers of systems control, especially those interested in multiagent systems, distributed and decentralized control, and structured systems. The book assumes no prior background in geometric control theory; however, a first year graduate course in linear control systems is desirable. Since not all control researchers today are exposed to geometric control theory, the book also adopts a tutorial style by way of examples that illustrate the geometric and abstract algebra concepts used in linear geometric control. In addition, the matrix calculations required for the studied control synthesis problems of linear multivariable control are illustrated via a set of running design examples. As such, some of the design examples are of higher dimension than one may typically see in a text; this is so that all the geometric features of the design problem are illuminated.
Rule-based transformations for geometric modelling
Directory of Open Access Journals (Sweden)
Thomas Bellet
2011-02-01
Full Text Available The context of this paper is the use of formal methods for topology-based geometric modelling. Topology-based geometric modelling deals with objects of various dimensions and shapes. Usually, objects are defined by a graph-based topological data structure and by an embedding that associates each topological element (vertex, edge, face, etc. with relevant data as their geometric shape (position, curve, surface, etc. or application dedicated data (e.g. molecule concentration level in a biological context. We propose to define topology-based geometric objects as labelled graphs. The arc labelling defines the topological structure of the object whose topological consistency is then ensured by labelling constraints. Nodes have as many labels as there are different data kinds in the embedding. Labelling constraints ensure then that the embedding is consistent with the topological structure. Thus, topology-based geometric objects constitute a particular subclass of a category of labelled graphs in which nodes have multiple labels.
Rule-based transformations for geometric modelling
Bellet, Thomas; Gall, Pascale Le; 10.4204/EPTCS.48.5
2011-01-01
The context of this paper is the use of formal methods for topology-based geometric modelling. Topology-based geometric modelling deals with objects of various dimensions and shapes. Usually, objects are defined by a graph-based topological data structure and by an embedding that associates each topological element (vertex, edge, face, etc.) with relevant data as their geometric shape (position, curve, surface, etc.) or application dedicated data (e.g. molecule concentration level in a biological context). We propose to define topology-based geometric objects as labelled graphs. The arc labelling defines the topological structure of the object whose topological consistency is then ensured by labelling constraints. Nodes have as many labels as there are different data kinds in the embedding. Labelling constraints ensure then that the embedding is consistent with the topological structure. Thus, topology-based geometric objects constitute a particular subclass of a category of labelled graphs in which nodes hav...
Quadratic 0-1 programming: Geometric methods and duality analysis
Liu, Chunli
The unconstraint quadratic binary problem (UBQP), as a classical combinatorial problem, finds wide applications in broad field and human activities including engineering, science, finance, etc. The NP-hardness of the combinatorial problems makes a great challenge to solve the ( UBQP). The main purpose of this research is to develop high performance solution method for solving (UBQP) via the geometric properties of the objective ellipse contour and the optimal solution. This research makes several contributions to advance the state-of-the-art of geometric approach of (UBQP). These contributions include both theoretical and numerical aspects as stated below. In part I of this dissertation, certain rich geometric properties hidden behind quadratic 0-1 programming are investigated. Especially, we derive new lower bounding methods and variable fixation techniques for quadratic 0-1 optimization problems by investigating geometric features of the ellipse contour of a (perturbed) convex quadratic function. These findings further lead to some new optimality conditions for quadratic 0-1 programming. Integrating these novel solution schemes into a proposed solution algorithm of a branch-and-bound type, we obtain promising preliminary computational results. In part II of this dissertation, we present new results of the duality gap between the binary quadratic optimization problem and its Lagrangian dual. We first derive a necessary and sufficient condition for the zero duality gap and discuss its relationship with the polynomial solvability of the problem. We then characterize the zeroness of duality gap by the distance, delta, between the binary set and certain affine space C. Finally, we discuss a computational procedure of the distance delta. These results provide new insights into the duality gap and polynomial solvability of binary quadratic optimization problems.
Hougardy, Stefan
2016-01-01
Algorithms play an increasingly important role in nearly all fields of mathematics. This book allows readers to develop basic mathematical abilities, in particular those concerning the design and analysis of algorithms as well as their implementation. It presents not only fundamental algorithms like the sieve of Eratosthenes, the Euclidean algorithm, sorting algorithms, algorithms on graphs, and Gaussian elimination, but also discusses elementary data structures, basic graph theory, and numerical questions. In addition, it provides an introduction to programming and demonstrates in detail how to implement algorithms in C++. This textbook is suitable for students who are new to the subject and covers a basic mathematical lecture course, complementing traditional courses on analysis and linear algebra. Both authors have given this "Algorithmic Mathematics" course at the University of Bonn several times in recent years.