Abstract

A kernel-based approach for nonlinear modeling of time series data is proposed in this paper. Autoregressive modeling is achieved in a feature space defined by a kernel function using a linear algorithm. The method extends the advantages of the conventional autoregressive models to characterization of nonlinear signals through the intelligent use of kernel functions.Experiments with synthetic signals demonstrate that this method seems to be a promising alternative to nonlinear modeling schemes.

Abstract

In this paper, we present a novel boosted robot vision control algorithm. The method utilizes on-line boosting to produce a strong vision-based robot control starting from two weak algorithms. The notion of weak and strong algorithms has been presented in the context of robot vision control, in presence of uncertainty in the measurement process. Appropriate probabilistic error functions are defined for the weak algorithm to evaluate their suitability in the task. An on-line boosting algorithm is employed to derive a final strong algorithm starting from two weak algorithms. This strong one has superior performance both in image and Cartesian spaces. Experiments justify this claim.

Abstract

Large graphs involving millions of vertices are common in many prac-tical applications and are challenging to process. Practical-time implementationsusing high-end computers are reported but are accessible only to a few. GraphicsProcessing Units (GPUs) of today have high computation power and low price.They have a restrictive programming model and are tricky to use. The G80 lineof Nvidia GPUs can be treated as a SIMD processor array using the CUDA pro-gramming model. We present a few fundamental algorithms – including breadthfirst search, single source shortest path, and all-pairs shortest path – using CUDAon large graphs. We can compute the single source shortest path on a 10 millionvertex graph in1.5seconds using the Nvidia 8800GTX GPU costing $600. Insome cases optimal sequential algorithm is not the fastest on the GPU architec-ture. GPUs have great potential as high-performance co-processors.

Abstract

Cluster-based tiled display walls can provide cost-effective and scalable displays with high resolution and a large displayarea. The software to drive them needs to scale too if arbitrarily large displays are to be built. Chromium is a popular software API usedto construct such displays. Chromium transparently renders any OpenGL application to a tiled display by partitioning and sendingindividual OpenGL primitives to each client per frame. Visualization applications often deal with massive geometric data with millions ofprimitives. Transmitting them every frame results in huge network requirements that adversely affect the scalability of the system. Inthis paper, we present Garuda, a client-server-based display wall framework that uses off-the-shelf hardware and a standard network.Garuda is scalable to large tile configurations and massive environments. It can transparently render any application built using theOpen Scene Graph (OSG) API to a tiled display without any modification by the user. The Garuda server uses an object-based scenestructure represented using a scene graph. The server determines the objects visible to each display tile using a novel adaptivealgorithm that culls the scene graph to a hierarchy of frustums. Required parts of the scene graph are transmitted to the clients, whichcache them to exploit the interframe redundancy. A multicast-based protocol is used to transmit the geometry to exploit the spatialredundancy present in tiled display systems. A geometry push philosophy from the server helps keep the clients in sync with oneanother. Neither the server nor a client needs to render the entire scene, making the system suitable for interactive rendering ofmassive models. Transparent rendering is achieved by intercepting the cull, draw, and swap functions of OSG and replacing them withour own. We demonstrate the performance and scalability of the Garuda system for different configurations of display wall. We alsoshow that the server and network loads grow sublinearly with the increase in the number of tiles, which makes our scheme suitable toconstruct very large displays

Abstract

Digitally recording dynamic events, such as sporting events, for experiencing in a spatio-temporally distant and arbitrary setting requires 4D capture: three dimensions for their geometry and appearance over the fourth dimension of time. Today's computer vision techniques make 4D capture possible. The virtualized reality system serves as an example on the general problem of digitizing dynamic events. In this article, we present the virtualized reality system's details from a historical perspective

Abstract

The advent of advanced graphics technologies and im-proved hardware has enabled the generation of highly com-plex models with huge number of triangles. Point-basedrepresentations and rendering have emerged as viable rep-resentations for high-quality models in this scenario. Thesemethods have been demonstrated only on high resolution,compact objects so far. They have to be adapted to environ-ments that extend over large areas to be considered seriousrepresentations. In this paper, we present an adaptation ofthe point-based representation to large, hierarchical envi-ronments. We show how point-based data can be generatedby sampling polygon-based representations. We also showthe combination of an object hierarchy and multiresolutionpoint representations and develop rendering algorithms forthe same. The multiresolution representation is constructedduring the generation process. We then show a hybrid rep-resentation in which the more complex portions of the envi-ronment are represented using points and others using theoriginal polygon-based representation. This produces bet-ter rendering performance by keeping large, flat regions astriangles. We demonstrate the method on the model of theFatehpur Sikri which has 14000 objects with over 500,000triangles

Abstract

Enthalpy entropy compensation effect has been a debatable topic for explaining the thermodynamic parameters in chemical reactions. Kinetic data for thermal degradation of chlorophylls (a, b and total) at 105145 C in coriander and mint leaf puree at pH 5.58.5 was used for this study. By applying the modified transition state theory and Krugs unbiased statistical regression procedure, the existence of thermodynamic compensation was tested for chlorophyll degradation. Enthalpy of activation (DH) for the coriander and mint purees ranged from 2.36 to 91.99 kJ/mol while entropy (DS) ranged from 0.047 to 0.713 kJ/(mol K). Though the enthalpy and entropy val- ues exhibited an excellent linear relationship (R2> 0.96), a critical analysis of the results indicated absence of any extra-thermodynamic effect or thermodynamic compensation for chlorophylls degradation. The presence of isokinetic point was also not detected.

Abstract

Optimal control theory is applied to obtain infrared laser pulses for selective vibrational excitation in a heteronuclear diatomic molecule. The problem of finding the optimized field is phrased as a maximization of a cost functional which depends on the laser field. A time dependent Gaussian factor is introduced in the field prior to evaluation of the cost functional for better field shape. Conjugate gradient method21,24 is used for optimization of constructed cost functional. At each instant of time, the optimal electric field is calculated and used for the subsequent quantum dynamics, within the dipole approximation. The results are obtained using both Morse potential as well as potential energy obtained using ab initio calculations.

Abstract

Binding of Gold Nanoclusters with Size-Expanded DNA Bases: A Computational Study of Structural and Electronic Properties Purshotam Sharma, Himanshu Singh, Sitansh Sharma, and Harjinder Singh* Center for Computational Natural Sciences and Bioinformatics, International Institute of Information and Technology, Gachibowli, Hyderabad-500032, India Received June 15, 2007 Abstract: Binding of gold nanoclusters with size-expanded DNA bases, xA, xC, xG, and xT, is studied using quantum chemical methods. Geometries of the neutral xA-Au6, xC-Au6, xG-Au6, and xT-Au6 complexes were fully optimized using the B3LYP density functional method (DFT). The gold clusters around xA and xT adopt triangular geometries, whereas irregular structures are obtained in the case of gold clusters complexed around xC and xG. The lengths of the bonds between atoms in the x-bases increase on gold complexation. The aromatic character of the x-bases also increases on gold complexation except for the five-member rings. A significant charge transfer from the x-base to gold atoms is seen in these complexes. Second-order interactions are observed in addition to direct covalent bonds between gold atoms and x-bases.

Abstract

Controlling molecular energetics using laser pulses is exemplified for nuclear motion in two different diatomic systems. The problem of finding the optimized field for maximizing a desired quantum dynamical target is formulated using an iterative method. The method is applied for two diatomic sys- tems, HF and OH. The power spectra of the fields and evolution of populations of different vibrational states during transitions are obtained.