Logarithmic barrier-augmented Lagrangian function to the optimal power flow problem

This paper presents a new approach to solve the Optimal Power Flow problem. This approach considers the application of logarithmic barrier method to voltage magnitude and tap-changing transformer variables and the other constraints are treated by augmented Lagrangian method. Numerical test results are presented, showing the effective performance of this algorithm. (C) 2005 Elsevier Ltd. All rights reserved.

A new approach to the solution of the optimal power flow problem based on the modified Newton's method associated to an augmented Lagrangian function

This paper presents a new algorithm for optimal power flow problem. The algorithm is based on Newton's method which it works with an Augmented Lagrangian function associated with the original problem. The function aggregates all the equality and inequality constraints and is solved using the modified-Newton method. The test results have shown the effectiveness of the approach using the IEEE 30 and 638 bus systems.

Existence of Lagrangians for the Yang-Mills equations

The Yang-Mills equations only admit a Lagrangian for gauge groups which are either semisimple or Abelian, or a direct product of groups of both kinds. © 1988.

Surveillance on the light-front gauge-fixing Lagrangians

In this work we propose two Lagrange multipliers with distinct coefficients for the light-front gauge that leads to the complete (non-reduced) propagator. This is accomplished via (n · A)2 + (∂ · A) 2 terms in the Lagrangian density. These lead to a well-defined and exact though Lorentz non invariant light-front propagator.

ARISupport - Interaction support for augmented reality systems

The communication between user and software is a basic stage in any Interaction System project. In interactive systems, this communication is established by the means of a graphical interface, whose objective is to supply a visual representation of the main entities and functions present in the Virtual Environment. New ways of interacting in computational systems have been minimizing the gap in the relationship between man and computer, and therefore enhancing its usability. The objective of this paper, therefore, is to present a proposal for a non-conventional user interface library called ARISupport, which supplies ARToolKit applications developers with an opportunity to create simple GUI interfaces, and provides some of the functionality used in Augmented Reality systems. © Springer-Verlag Berlin Heidelberg 2005.

Support on the remote interaction for augmented reality system

This article presents a support on the remote interaction for utilization in augmented reality systems based on ARToolkit. It utilizes the multicast communication in order to improve the scalability of distributed environment. This support may be utilized in production of specific applications pointed to distance education, training and entertainment. The validity of support happened with the implementation of a prototype and realization of tests for communication latency analysis and frames per second rate. © 2007 IEEE.

Mutual occlusion between real and virtual elements in Augmented Reality based on fiducial markers

Augmented Reality (AR) systems which use optical tracking with fiducial marker for registration have had an important role in popularizing this technology, since only a personal computer with a conventional webcam is required. However, in most these applications, the virtual elements are shown only in the foreground a real element does not occlude a virtual one. The method presented enables AR environments based on fiducial markers to support mutual occlusion between a real element and many virtual ones, according to the elements position (depth) in the environment. © 2012 IEEE.

Healing outcomes at implants installed in sites augmented with particulate autologous bone and xenografts. An experimental study in dogs

Aim: To evaluate the integration of implants installed at the interface of pristine and grafted tissue augmented with particulate autologous bone or deproteinized bovine bone mineral (DBBM), concomitantly with a collagen membrane. Material and methods: In 6 Labrador dogs, the distal root of 3P3 and 4P4 was endodontically treated and hemi-sected, and the mesial roots extracted concomitantly with the extraction of 2P2. The buccal bony walls were removed, and two box-shaped defects, one larger and one smaller, were created. After 3 months, flaps were elevated, and the defects were filled with particulate autologous bone or DBBM in the right and left side of the mandible, respectively. Collagen membranes were used to cover the grafted areas. Three months later, flaps were elevated, and a customized device was used as surgical guide to prepare the recipient sites at the interface between grafts and pristine bone. One implant was installed in each of the four defects. After 3 months, biopsies were harvested and ground sections prepared for histological evaluation. Results: The augmentation technique was effective at all sites and all the foreseen implants were installed. In the histological analysis, all implants were integrated in mature bone, at both the buccal and lingual aspects. The most coronal bone-to-implant contact and the top of the buccal bony crest were located at a similar distance between test and control implants. However, these distances were higher at the larger compared with the smaller defects. Especially in the large defect, residual particles of DBBM were found embedded into connective tissue and located outside the bony crest. Conclusions: Particulate autologous bone as well as DBBM particles used to augment horizontally the alveolar bony process allowed for the osseointegration of implants installed after 3 months of healing. © 2012 John Wiley & Sons A/S.

ARBOT: augmented reality system for teaching logic algorithmic

This article purposes the ARBot, a system that has as main objective the presentation of concepts of logic for students of elementary and secondary education. The system was developed using the technology known as Augmented Reality (AR), which allows complement the actual environment where the user is, by adding virtual objects. In this scenario the RA created from a virtual game interface is used, through which cognitive challenges are presented. To solve these challenges, users must set up three-dimensional virtual characters using visual language. As a result it follows that, in a playful way, concepts of algorithms and programming are assimilated by users. In addition, the system enables two users to interact in a cooperative game mode. In cooperative mode, the system focuses on collaborative learning, since it allows users to jointly solve the cognitive challenge presented by the system.

Augmented nitric oxide production and up-regulation of endothelial nitric oxide synthase during cecal ligation and perforation

Nitric oxide (NO) has been pointed out as being the main mediator involved in the hypotension and tissue injury taking place during sepsis. This study aimed to investigate the cellular mechanisms implicated in the acetylcholine (ACh)-induced relaxation detected in aortic rings isolated from rats submitted to cecal ligation and perforation (CLP group), 6 h post-CLP. The mean arterial pressure was recorded, and the concentration-effect curves for ACh were constructed for endothelium-intact aortic rings in the absence (control) or after incubation with one of the following NO synthase inhibitors: L-NAME (non-selective), L-NNA (more selective for eNOS), 7-nitroindazole (more selective for nNOS), or 1400W (selective for iNOS). The NO concentration was determined by using confocal microscopy. The protein expression of the NOS isoforms was quantified by Western blot analysis. The prostacyclin concentration was indirectly analyzed on the basis of 6-keto-prostaglandin F-1 alpha (6-keto-PGF(1 alpha)) levels measured by enzyme immunoassay. There were no differences between Sham- and CLP-operated rats in terms of the relaxation induced by acetylcholine. However, the NOS inhibitors reduced this relaxation in both groups, but this effect remained more pronounced in the CLP group as compared to the Sham group. The acetylcholine-induced NO production was higher in the rat aortic endothelial cells of the CLP group than in those of the Sham group. eNOS protein expression was larger in the CLP group, but the iNOS protein was not verified in any of the groups. The basal 6-keto-PGF(1 alpha) levels were higher in the CLP group, but the acetylcholine-stimulated levels did not increase in CLP as much as they did in the Sham group. Taken together, our results show that the augmented NO production in sepsis syndrome elicited by cecal ligation and perforation is due to eNOS up-regulation and not to iNOS. (C) 2012 Elsevier Inc. All rights reserved.

Augmented Lagrangian method with nonmonotone penalty parameters for constrained optimization

At each outer iteration of standard Augmented Lagrangian methods one tries to solve a box-constrained optimization problem with some prescribed tolerance. In the continuous world, using exact arithmetic, this subproblem is always solvable. Therefore, the possibility of finishing the subproblem resolution without satisfying the theoretical stopping conditions is not contemplated in usual convergence theories. However, in practice, one might not be able to solve the subproblem up to the required precision. This may be due to different reasons. One of them is that the presence of an excessively large penalty parameter could impair the performance of the box-constraint optimization solver. In this paper a practical strategy for decreasing the penalty parameter in situations like the one mentioned above is proposed. More generally, the different decisions that may be taken when, in practice, one is not able to solve the Augmented Lagrangian subproblem will be discussed. As a result, an improved Augmented Lagrangian method is presented, which takes into account numerical difficulties in a satisfactory way, preserving suitable convergence theory. Numerical experiments are presented involving all the CUTEr collection test problems.

The boundedness of penalty parameters in an augmented Lagrangian method with constrained subproblems

Augmented Lagrangian methods are effective tools for solving large-scale nonlinear programming problems. At each outer iteration, a minimization subproblem with simple constraints, whose objective function depends on updated Lagrange multipliers and penalty parameters, is approximately solved. When the penalty parameter becomes very large, solving the subproblem becomes difficult; therefore, the effectiveness of this approach is associated with the boundedness of the penalty parameters. In this paper, it is proved that under more natural assumptions than the ones employed until now, penalty parameters are bounded. For proving the new boundedness result, the original algorithm has been slightly modified. Numerical consequences of the modifications are discussed and computational experiments are presented.

Augmented reality in sport scenarios using cameras mounted on a tripod

[ES] In this paper we address the problem of inserting virtual content in a video sequence. The method we propose uses just image information. We perform primitive tracking, camera calibration, real and virtual camera synchronisation and finally rendering to insert the virtual content in the real video sequence. To simplify the calibration step we assume that cameras are mounted on a tripod (which is a common situation in practise). The primitive tracking procedure, which uses lines and circles as primitives, is performed by means of a CART (Classification and Regression Tree). Finally, the virtual and real camera synchronisation and rendering is performed using functions of OpenGL (Open Graphic Library). We have applied the method proposed to sport event scenarios, specifically, soccer matches. In order to illustrate its performance, it has been applied to real HD (High Definition) video sequences. The quality of the proposed method is validated by inserting virtual elements in such HD video sequence.