Abstract: This paper presents the application of a signal intensity independent registration criterion for non-rigid body registration of medical images. The criterion is defined as the weighted ratio image of two images. The ratio is computed on a voxel per voxel basis and weighting is performed by setting the ratios between signal and background voxels to a standard high value. The mean squared value of the weighted ratio is computed over the union of the signal areas of the two images and it is minimized using the Chebyshev polynomial approximation. The geometric transformation model adopted is a local cubic B-splines based model.
Abstract: Although many researchers have studied the flow
hydraulics in compound channels, there are still many complicated problems in determination of their flow rating curves. Many different
methods have been presented for these channels but extending them
for all types of compound channels with different geometrical and
hydraulic conditions is certainly difficult. In this study, by aid of nearly 400 laboratory and field data sets of geometry and flow rating
curves from 30 different straight compound sections and using artificial neural networks (ANNs), flow discharge in compound channels was estimated. 13 dimensionless input variables including relative depth, relative roughness, relative width, aspect ratio, bed
slope, main channel side slopes, flood plains side slopes and berm
inclination and one output variable (flow discharge), have been used
in ANNs. Comparison of ANNs model and traditional method
(divided channel method-DCM) shows high accuracy of ANNs model results. The results of Sensitivity analysis showed that the relative depth with 47.6 percent contribution, is the most effective input parameter for flow discharge prediction. Relative width and
relative roughness have 19.3 and 12.2 percent of importance, respectively. On the other hand, shape parameter, main channel and
flood plains side slopes with 2.1, 3.8 and 3.8 percent of contribution, have the least importance.
Abstract: The class of geometric deformable models, so-called
level sets, has brought tremendous impact to medical imagery. In
this paper we present yet another application of level sets to medical
imaging. The method we give here will in a way modify the speed
term in the standard level sets equation of motion. To do so we
build a potential based on the distance and the gradient of the
image we study. In turn the potential gives rise to the force field:
F~F(x, y) = P
∀(p,q)∈I
((x, y) - (p, q)) |ÔêçI(p,q)|
|(x,y)-(p,q)|
2 . The direction
and intensity of the force field at each point will determine the
direction of the contour-s evolution. The images we used to test
our method were produced by the Univesit'e de Sherbrooke-s PET
scanners.
Abstract: Effect of geometry on crushing behavior, energy absorption and failure mode of woven roving jute fiber/epoxy laminated composite tubes were experimentally studied. Investigations were carried out on three different geometrical types of composite tubes (circular, square and radial corrugated) subjected to axial compressive loading. It was observed in axial crushing study that the load bearing capability is significantly influenced by corrugation geometry. The influence of geometries of specimens was supported by the plotted load – displacement curves of the tests.
Abstract: An alternative iterative computational procedure is
proposed for internal normal ball loads calculation in statically
loaded single-row, angular-contact ball bearings, subjected to a
known thrust load, which is applied in the inner ring at the geometric
bearing center line. An accurate method for curvature radii at
contacts with inner and outer raceways in the direction of the motion
is used. Numerical aspects of the iterative procedure are discussed.
Numerical examples results for a 218 angular-contact ball bearing
have been compared with those from the literature. Twenty figures
are presented showing the geometrical features, the behavior of the
convergence variables and the following parameters as functions of
the thrust load: normal ball loads, contact angle, distance between
curvature centers, and normal ball and axial deflections.
Abstract: In the recent years, functionally gradient materials (FGMs) have gained considerable attention in the high temperature environment applications. In this paper, free vibration of thin functionally graded cylindrical shell with hole composed of stainless steel and zirconia is studied. The mechanical properties vary smoothly and continuously from one surface to the other according to a volume fraction power-law distribution. The Influence of shell geometrical parameters, variations of volume fractions and boundary conditions on natural frequency is considered. The equations of motion are based on strains-displacement relations from Love-s shell theory and Rayleigh method. The results have been obtained for natural frequencies of cylindrical shell with holes for different shape, number and location in this paper.
Abstract: Considering complexity of products, new geometrical
design and investment tolerances that are necessary, measuring and
dimensional controlling involve modern and more precise methods.
Photo digitizing method using two cameras to record pictures and
utilization of conventional method named “cloud points" and data
analysis by the use of ATOUS software, is known as modern and
efficient in mentioned context. In this paper, benefits of photo
digitizing method in evaluating sampling of machining processes
have been put forward. For example, assessment of geometrical
integrity surface in 5-axis milling process and measurement of
carbide tool wear in turning process, can be can be brought forward.
Advantages of this method comparing to conventional methods have
been expressed.
Abstract: This article presents a performance comparison of an
interior mounted permanent magnet synchronous generator (IPMSG)
with a synchronous reluctance generator (SynRG) with the same size
for a wind application. It is found that using the same geometrical
dimensions, a SynRG can convert 74 % of the power that an IPMSG
can convert, while it has 80% of the IPMSG weight. Moreover it is
found that the efficieny for the IMPSG is 99% at rated power
compared to 98.7% for the SynRG.
Abstract: Finding the shortest path between two positions is a
fundamental problem in transportation, routing, and communications
applications. In robot motion planning, the robot should pass around
the obstacles touching none of them, i.e. the goal is to find a
collision-free path from a starting to a target position. This task has
many specific formulations depending on the shape of obstacles,
allowable directions of movements, knowledge of the scene, etc.
Research of path planning has yielded many fundamentally different
approaches to its solution, mainly based on various decomposition
and roadmap methods. In this paper, we show a possible use of
visibility graphs in point-to-point motion planning in the Euclidean
plane and an alternative approach using Voronoi diagrams that
decreases the probability of collisions with obstacles. The second
application area, investigated here, is focused on problems of finding
minimal networks connecting a set of given points in the plane using
either only straight connections between pairs of points (minimum
spanning tree) or allowing the addition of auxiliary points to the set
to obtain shorter spanning networks (minimum Steiner tree).
Abstract: This paper presents an effective traffic lights detection
method at the night-time. First, candidate blobs of traffic lights are
extracted from RGB color image. Input image is represented on the
dominant color domain by using color transform proposed by Ruta,
then red and green color dominant regions are selected as candidates.
After candidate blob selection, we carry out shape filter for noise
reduction using information of blobs such as length, area, area of
boundary box, etc. A multi-class classifier based on SVM (Support
Vector Machine) applies into the candidates. Three kinds of features
are used. We use basic features such as blob width, height, center
coordinate, area, area of blob. Bright based stochastic features are also
used. In particular, geometric based moment-s values between
candidate region and adjacent region are proposed and used to improve
the detection performance. The proposed system is implemented on
Intel Core CPU with 2.80 GHz and 4 GB RAM and tested with the
urban and rural road videos. Through the test, we show that the
proposed method using PF, BMF, and GMF reaches up to 93 % of
detection rate with computation time of in average 15 ms/frame.
Abstract: A new hybrid coding method for compressing
animated polygonal meshes is presented. This paper assumes
the simplistic representation of the geometric data: a temporal
sequence of polygonal meshes for each discrete frame of the
animated sequence. The method utilizes a delta coding and an
octree-based method. In this hybrid method, both the octree
approach and the delta coding approach are applied to each
single frame in the animation sequence in parallel. The
approach that generates the smaller encoded file size is chosen
to encode the current frame. Given the same quality
requirement, the hybrid coding method can achieve much
higher compression ratio than the octree-only method or the
delta-only method. The hybrid approach can represent 3D
animated sequences with higher compression factors while
maintaining reasonable quality. It is easy to implement and have
a low cost encoding process and a fast decoding process, which
make it a better choice for real time application.
Abstract: This paper aims to present a survey of object
recognition/classification methods based on image moments. We
review various types of moments (geometric moments, complex
moments) and moment-based invariants with respect to various
image degradations and distortions (rotation, scaling, affine
transform, image blurring, etc.) which can be used as shape
descriptors for classification. We explain a general theory how to
construct these invariants and show also a few of them in explicit
forms. We review efficient numerical algorithms that can be used
for moment computation and demonstrate practical examples of
using moment invariants in real applications.
Abstract: Drop-in of R-22 alternatives in refrigeration and air conditioning systems requires a redesign of system components to improve system performance and reliability with the alternative refrigerants. The present paper aims at design adiabatic capillary tubes for R-22 alternatives such as R-417A, R-422D and R-438A. A theoretical model has been developed and validated with the available experimental data from literature for R-22 over a wide range of both operating and geometrical parameters. Predicted lengths of adiabatic capillary tube are compared with the lengths of the capillary tube needed under similar experimental conditions and majority of predictions are found to be within 4.4% of the experimental data. Hence, the model has been applied for R-417A, R- 422D and R-438A and capillary tube selection charts and correlations have been computed. Finally a comparison between the selected refrigerants and R-22 has been introduced and the results showed that R-438A is the closest one to R-22.
Abstract: Generally flow behavior in centrifugal fan is observed
to be in a state of instability with flow separation zones on suction
surface as well as near the front shroud. Overall performance of the
diffusion process in a centrifugal fan could be enhanced by
judiciously introducing the boundary layer suction slots. With easy
accessibility of CFD as an analytical tool, an extensive numerical
whole field analysis of the effect of boundary layer suction slots in
discrete regions of suspected separation points is possible. This paper
attempts to explore the effect of boundary layer suction slots
corresponding to various geometrical locations on the impeller with
converging configurations for the slots. The analysis shows that the
converging suction slots located on the impeller blade about 25%
from the trailing edge, significantly improves the static pressure
recovery across the fan. Also it is found that Slots provided at a
radial distance of about 12% from the leading and trailing edges
marginally improve the static pressure recovery across the fan.
Abstract: The two-dimensional gel electrophoresis method
(2-DE) is widely used in Proteomics to separate thousands of proteins
in a sample. By comparing the protein expression levels of proteins in
a normal sample with those in a diseased one, it is possible to identify
a meaningful set of marker proteins for the targeted disease. The major
shortcomings of this approach involve inherent noises and irregular
geometric distortions of spots observed in 2-DE images. Various
experimental conditions can be the major causes of these problems. In
the protein analysis of samples, these problems eventually lead to
incorrect conclusions. In order to minimize the influence of these
problems, this paper proposes a partition based pair extension method
that performs spot-matching on a set of gel images multiple times and
segregates more reliable mapping results which can improve the
accuracy of gel image analysis. The improved accuracy of the
proposed method is analyzed through various experiments on real
2-DE images of human liver tissues.
Abstract: In this paper, a novel scheme is proposed for ownership identification and authentication using color images by deploying Cryptography and Digital Watermarking as underlaying technologies. The former is used to compute the contents based hash and the latter to embed the watermark. The host image that will claim to be the rightful owner is first transformed from RGB to YST color space exclusively designed for watermarking based applications. Geometrically YS ÔèÑ T and T channel corresponds to the chrominance component of color image, therefore suitable for embedding the watermark. The T channel is divided into 4×4 nonoverlapping blocks. The size of block is important for enhanced localization, security and low computation. Each block along with ownership information is then deployed by SHA160, a one way hash function to compute the content based hash, which is always unique and resistant against birthday attack instead of using MD5 that may raise the condition i.e. H(m)=H(m'). The watermark payload varies from block to block and computed by the variance factorα . The quality of watermarked images is quite high both subjectively and objectively. Our scheme is blind, computationally fast and exactly locates the tampered region.
Abstract: This paper addresses the development of an intelligent vision system for human-robot interaction. The two novel contributions of this paper are 1) Detection of human faces and 2) Localizing the eye. The method is based on visual attributes of human skin colors and geometrical analysis of face skeleton. This paper introduces a spatial domain filtering method named ?Fuzzily skewed filter' which incorporates Fuzzy rules for deciding the gray level of pixels in the image in their neighborhoods and takes advantages of both the median and averaging filters. The effectiveness of the method has been justified over implementing the eye tracking commands to an entertainment robot, named ''AIBO''.
Abstract: In the proposed method for Web page-ranking, a
novel theoretic model is introduced and tested by examples of order
relationships among IP addresses. Ranking is induced using a
convexity feature, which is learned according to these examples
using a self-organizing procedure. We consider the problem of selforganizing
learning from IP data to be represented by a semi-random
convex polygon procedure, in which the vertices correspond to IP
addresses. Based on recent developments in our regularization
theory for convex polygons and corresponding Euclidean distance
based methods for classification, we develop an algorithmic
framework for learning ranking functions based on a Computational
Geometric Theory. We show that our algorithm is generic, and
present experimental results explaining the potential of our approach.
In addition, we explain the generality of our approach by showing its
possible use as a visualization tool for data obtained from diverse
domains, such as Public Administration and Education.
Abstract: To determine the length of engagement threads of a bolt installed in a tapped part in order to avoid the threads stripping remains a very current problem in the design of the thread assemblies. It does not exist a calculation method formalized for the cases where the bolt is screwed directly in a ductile material. In this article, we study the behavior of the threads stripping of a loaded assembly by using a modelling by finite elements and a rupture criterion by damage. This modelling enables us to study the different parameters likely to influence the behavior of this bolted connection. We study in particular, the influence of couple of materials constituting the connection, of the bolt-s diameter and the geometrical characteristics of the tapped part, like the external diameter and the length of engagement threads. We established an experiments design to know the most significant parameters. That enables us to propose a simple expression making possible to calculate the resistance of the threads whatever the metallic materials of the bolt and the tapped part. We carried out stripping tests in order to validate our model. The estimated results are very close to those obtained by the tests.
Abstract: Shape memory alloy (SMA) actuators have found a
wide range of applications due to their unique properties such as high
force, small size, lightweight and silent operation. This paper presents
the development of compact (SMA) actuator and cooling system in
one unit. This actuator is developed for multi-fingered hand. It
consists of nickel-titanium (Nitinol) SMA wires in compact forming.
The new arrangement insulates SMA wires from the human body by
housing it in a heat sink and uses a thermoelectric device for rejecting
heat to improve the actuator performance. The study uses
optimization methods for selecting the SMA wires geometrical
parameters and the material of a heat sink. The experimental work
implements the actuator prototype and measures its response.