Fast Object Segmentation by Growing Minimal Paths from a Single Point on 2D or 3D Images

In this paper, we present a new method for segmenting closed contours and surfaces. Our work builds on a variant of the minimal path approach. First, an initial point on the desired contour is chosen by the user. Next, new keypoints are detected automatically using a front propagation approach. We assume that the desired object has a closed boundary. This a-priori knowledge on the topology is used to devise a relevant criterion for stopping the keypoint detection and front propagation. The final domain visited by the front will yield a band surrounding the object of interest. Linking pairs of neighboring keypoints with minimal paths allows us to extract a closed contour from a 2D image. This approach can also be used for finding an open curve giving extra information as stopping criteria. Detection of a variety of objects on real images is demonstrated. Using a similar idea, we can extract networks of minimal paths from a 3D image called Geodesic Meshing. The proposed method is applied to 3D data with promising results.

A Novel Theoretical Investigation of Electronic Structure and Half-Metallic Ferromagnetism in 3d (V)-Doped InP for Spintronic Applications

We have investigated the electronic structure and half-metallic ferromagnetic properties of vanadium (V)-doped InP indium phosphide in the zinc blende structure as ternary In _1?x V _x P compounds at concentrations x = 0.25, 0.5, and 0.75 of V, using first-principles calculations of density functional theory with generalized gradient approximation functional of Wu and Cohen (GGA-WC). It is found that In _0.75 V _0.25P, In _0.5 V _0.5P, and In _0.25 V _0.75P compounds depicted a half-metallic (HM) ferromagnetic character with spin polarization of 100 % at Fermi level. The HM ferromagnetic behavior is confirmed by the integral Bohr magneton of total magnetic moment of 2 μ _B per V atom of In _1?x V _x P, which mainly arises from the 3d (V) states along with less important contributions of induced local magnetic moments at In and P sites. Therefore, the In _1?x V _x P material seems to be potential candidate for possible semiconductor spintronics applications.     

A design of a tunable hybrid Solc filter for 40-Gbps DWDM optical systems

In this paper, a contribution for enhancing the performance of a hybrid tunable Solc filter for 40-Gbps DWDM systems is presented. By using liquid crystal cells with variable birefringence, we have achieved a wavelength tuning of 33 ITU channels, for a 100-GHz frequency spacing, from 1564.69 to 1530.32 nm via a 10-stage hybrid Solc filter. The designed device presents a tuning step of 0.1 nm by applying a voltage difference of 0.2 V. The optical cancelling technique is used to make a 3-dB bandwidth tuning between 0.31 and 1.4 nm. The channel’s bandwidth is adjusted for different kinds of 40-Gbps modulated channels spectra. The 10-stage hybrid Solc filter provides theoretically an insertion loss of 4.6 dB, by using polarizers and birefringent plates characterized by high anti-reflection coatings, while its crosstalk approximates 14 dB. The proposed filter provides very low polarization-dependent loss through the incorporation of a polarization beam splitter and a polarization beam combiner.     

First-principle calculations of electronic and ferromagnetic properties of $$\hbox {Al}_{1-x}\hbox {V}_{x}\hbox {Sb}$$

We have used the first-principle calculations of density functional theory within full-potential linearized augmented plane-wave method to investigate the electronic and ferromagnetic properties of \(\hbox {Al}_{1-x}\hbox {V}_{x}\hbox {Sb}\) alloys. The electronic structures of \(\hbox {Al}_{0.25}\hbox {V}_{0.75}\hbox {Sb}, \hbox {Al}_{0.5}\hbox {V}_{0.5}\hbox {Sb}\) and \(\hbox {Al}_{0.75}\hbox {V}_{0.25}\hbox {Sb}\) exhibit a half-metallic ferromagnetic character with spin polarization of 100 %. The total magnetic moment per V atom for each compound is integral Bohr magneton of 2 \(\mu _{\mathrm{B}}\), confirming the half-metallic feature of \(\hbox {Al}_{1-x}\hbox {V}_{x}\hbox {Sb}\). Therefore, these materials are half-metallic ferromagnets useful for possible spintronics applications.     

Design of a 1 × 2 novel optical switch based on polarization converters and splitters

In this paper, a 1?×?2 optical switch based on two TE/TM polarization converters, one 1?×?2-polarization beam splitter and a hybrid 2?×?2-polarization beam splitter/combiner is designed and discussed. The novelty of this work resides in the design of a 2?×?2-hybrid polarization beam combiner/splitter, operating as a 2?×?2 polarization optical switch through the combining and the splitting of polarized signals issued from two TE/TM polarization controllers. The novel hybrid splitter/combiner can route an optical signal either to a bar or a cross port with an extinction ratio higher than 90 dB, thanks to the feature of polarization splitting used in this device to suppress undesired polarization states and minimize the polarization-dependent loss. We have used polarization beam converters to switch between two orthogonal modes in order to facilitate the routing of these signals through the 2?×?2-hybrid polarization splitter/combiner. We changed the polarization states of signals, in our simulation via OptiSystem, through polarization controllers, by modifying only their phase shifts between 0 rad and π rad. The proposed 1?×?2 optical switch presents an average insertion loss of 3.5 dB.

     

QoS-aware optimal and automated semantic web service composition with user’s constraints

Automated semantic web service composition is one of the critical research challenges of service-oriented computing, since it allows users to create an application simply by specifying the inputs that the application requires, the outputs it should produce, and any constraints it should respect. The composition problem has been handled using a variety of techniques, from artificial intelligence planning to optimization algorithms. However no approach so far has focused on handling three composition dimensions simultaneously, producing solutions that are: (1) fully functional (i.e., fully executable) by using a mechanism of semantic matching between the services involved in the solutions, (2) are optimized according to non-functional quality-of-service (QoS) measurements, and (3) respect global QoS constraints. This paper presents a novel approach based on a Harmony Search algorithm that addresses these three dimensions simultaneously through a fitness function, to select the optimal or near-optimal solution in semantic web service composition. In our approach, the search space is modeled as a planning-graph structure which encodes all the possible composition solutions for a given user request. To improve the selection process we have compared the original Harmony Search algorithm with its recently developed variants Improved Harmony Search (IHS) algorithm and Global Best Harmony Search (GHS) algorithm. An experimentation of the approach conducted with an extended version of the Web Service Challenge 2009 dataset showed that: (1) our approach is efficient and effective to extract the optimal or near-optimal composition in diverse scenarios; and (2) both variants IHS and GHS algorithms have brought improvements in terms of fitness and execution time.     

Tubular Structure Segmentation Based on Minimal Path Method and Anisotropic Enhancement

We present a new interactive method for tubular structure extraction. The main application and motivation for this work is vessel tracking in 2D and 3D images. The basic tools are minimal paths solved using the fast marching algorithm. This allows interactive tools for the physician by clicking on a small number of points in order to obtain a minimal path between two points or a set of paths in the case of a tree structure. Our method is based on a variant of the minimal path method that models the vessel as a centerline and surface. This is done by adding one dimension for the local radius around the centerline. The crucial step of our method is the definition of the local metrics to minimize. We have chosen to exploit the tubular structure of the vessels one wants to extract to built an anisotropic metric. The designed metric is well oriented along the direction of the vessel, admits higher velocity on the centerline, and provides a good estimate of the vessel radius. Based on the optimally oriented flux this measure is required to be robust against the disturbance introduced by noise or adjacent structures with intensity similar to the target vessel. We obtain promising results on noisy synthetic and real 2D and 3D images and we present a clinical validation.     

Electronic and Ferromagnetic Properties of 3<Emphasis Type="Italic">d</Emphasis>(V)-Doped (BaS) Barium Sulfide

The objective of this study is to investigate the electronic structure and ferromagnetic properties of barium sulfide (BaS) doped with vanadium (V) impurity. The calculations were performed by using the first-principle calculations of density functional theory. The lattice constant of Ba_1?x V _x S decreases with increasing concentration (x) of the V atom. We have found that the Ba_0.75 V _0.25S and Ba_0.5 V _0.5S compounds are half-metallic ferromagnets with total magnetic moments of 3 μ _B per V atom, while for high concentration x = 0.75, the Ba_0.25 V _0.75S becomes nearly half metallic due to broadening of 3d (V) states in the gap. The exchange coupling between the 3d (V) levels and conduction bands is ferromagnetic, confirming the magnetic nature of Ba_1?x V _x S compounds.