Abstract: Anultra-low power capacitor less low-dropout voltage
regulator with improved transient response using gain enhanced feed
forward path compensation is presented in this paper. It is based on a
cascade of a voltage amplifier and a transconductor stage in the feed
forward path with regular error amplifier to form a composite gainenhanced
feed forward stage. It broadens the gain bandwidth and thus
improves the transient response without substantial increase in power
consumption. The proposed LDO, designed for a maximum output
current of 100 mA in UMC 180 nm, requires a quiescent current of
69 )A. An undershot of 153.79mV for a load current changes from
0mA to 100mA and an overshoot of 196.24mV for current change of
100mA to 0mA. The settling time is approximately 1.1 )s for the
output voltage undershooting case. The load regulation is of 2.77
)V/mA at load current of 100mA. Reference voltage is generated by
using an accurate band gap reference circuit of 0.8V.The costly
features of SOC such as total chip area and power consumption is
drastically reduced by the use of only a total compensation
capacitance of 6pF while consuming power consumption of 0.096
mW.
Abstract: Composite materials have important assets compared
to traditional materials. They bring many functional advantages:
lightness, mechanical resistance and chemical, etc. In the present
study we examine the effect of a circular central notch and a precrack
on the tensile fracture of two woven composite materials. The tensile
tests were applied to a standardized specimen, notched and a
precarcked (orientation of the crack 0°, 45° and 90°). These tensile
tests were elaborated according to an experimental planning design of
the type 23.31 requiring 24 experiments with three repetitions. By the
analysis of regression, we obtained a mathematical model describing
the maximum load according to the influential parameters (hole
diameter, precrack length, angle of a precrack orientation). The
specimens precracked at 90° have a better behavior than those having
a precrack at 45° and still better than those having of the precracks
oriented at 0°. In addition the maximum load is inversely
proportional to the notch size.
Abstract: The paper describes the experiments and the kinetic
parameters calculus of the gasoil hydrofining. They are presented
experimental results of gasoil hidrofining using Mo and promoted
with Ni on aluminum support catalyst. The authors have adapted a
kinetic model gasoil hydrofining. Using this proposed kinetic model
and the experimental data they have calculated the parameters of the
model. The numerical calculus is based on minimizing the difference
between the experimental sulf concentration and kinetic model
estimation.
Abstract: The relationship between eigenstructure (eigenvalues
and eigenvectors) and latent structure (latent roots and latent vectors)
is established. In control theory eigenstructure is associated with
the state space description of a dynamic multi-variable system and
a latent structure is associated with its matrix fraction description.
Beginning with block controller and block observer state space forms
and moving on to any general state space form, we develop the
identities that relate eigenvectors and latent vectors in either direction.
Numerical examples illustrate this result. A brief discussion of the
potential of these identities in linear control system design follows.
Additionally, we present a consequent result: a quick and easy
method to solve the polynomial eigenvalue problem for regular matrix
polynomials.
Abstract: Three dimensional non-Interlaced carbon fibre
reinforced silicon carbide (3-D-Cf/SiC) composites with pyrocarbon
interphase were fabricated using isothermal chemical vapor
infiltration (ICVI) combined with polymer impregnation pyrolysis
(PIP) process. Polysilazane (PSZ) is used as a preceramic polymer to
obtain silicon carbide matrix. Thermo gravimetric analysis (TGA),
Infrared spectroscopic analysis (IR) and X-ray diffraction (XRD)
analysis were carried out on PSZ pyrolysed at different temperatures
to understand the pyrolysis and obtaining the optimum pyrolysing
condition to yield β-SiC phase. The density of the composites was
1.94 g cm-3 after the 3-D carbon preform was SiC infiltrated for 280 h
with one intermediate polysilazane pre-ceramic PIP process.
Mechanical properties of the composite materials were investigated
under tensile, flexural, shear and impact loading. The values of
tensile strength were 200 MPa at room temperature (RT) and 195
MPa at 500°C in air. The average RT flexural strength was 243 MPa.
The lower flexural strength of these composites is because of the
porosity. The fracture toughness obtained from single edge notched
beam (SENB) technique was 39 MPa.m1/2. The work of fracture
obtained from the load-displacement curve of SENB test was 22.8
kJ.m-2. The composites exhibited excellent impact resistance and the
dynamic fracture toughness of 44.8 kJ.m-2 is achieved as determined
from instrumented Charpy impact test. The shear strength of the
composite was 93 MPa, which is significantly higher compared 2-D
Cf/SiC composites. Microstructure evaluation of fracture surfaces
revealed the signatures of fracture processes and showed good
support for the higher toughness obtained.
Abstract: This paper is concerned with the stability problem
with two additive time-varying delay components. By choosing one
augmented Lyapunov-Krasovskii functional, using some new zero
equalities, and combining linear matrix inequalities (LMI)
techniques, two new sufficient criteria ensuring the global stability
asymptotic stability of DNNs is obtained. These stability criteria are
present in terms of linear matrix inequalities and can be easily
checked. Finally, some examples are showed to demonstrate the
effectiveness and less conservatism of the proposed method.
Abstract: Phase equilibria of AZ91D Mg alloys for
nonflammable use, containing Ca and Y, were carried out by using
FactSage® and FTLite database, which revealed that solid solution
treatment could be performed at temperatures from 400 to 450oC.
Solid solution treatment of AZ91D Mg alloy without Ca and Y was
successfully conducted at 420oC and supersaturated microstructure
with all beta phase resolved into matrix was obtained. In the case of
AZ91D Mg alloy with some Ca and Y; however, a little amount of
intermetallic particles were observed after solid solution treatment.
After solid solution treatment, each alloy was annealed at temperatures
of 180 and 200oC for time intervals from 1 min to 48 hrs and hardness
of each condition was measured by micro-Vickers method. Peak aging
conditions were deduced as at the temperature of 200oC for 10 hrs.
Abstract: Analysis of real life problems often results in linear
systems of equations for which solutions are sought. The method to
employ depends, to some extent, on the properties of the coefficient
matrix. It is not always feasible to solve linear systems of equations
by direct methods, as such the need to use an iterative method
becomes imperative. Before an iterative method can be employed
to solve a linear system of equations there must be a guaranty that
the process of solution will converge. This guaranty, which must
be determined apriori, involve the use of some criterion expressible
in terms of the entries of the coefficient matrix. It is, therefore,
logical that the convergence criterion should depend implicitly on the
algebraic structure of such a method. However, in deference to this
view is the practice of conducting convergence analysis for Gauss-
Seidel iteration on a criterion formulated based on the algebraic
structure of Jacobi iteration. To remedy this anomaly, the Gauss-
Seidel iteration was studied for its algebraic structure and contrary
to the usual assumption, it was discovered that some property of the
iteration matrix of Gauss-Seidel method is only diagonally dominant
in its first row while the other rows do not satisfy diagonal dominance.
With the aid of this structure we herein fashion out an improved
version of Gauss-Seidel iteration with the prospect of enhancing
convergence and robustness of the method. A numerical section is
included to demonstrate the validity of the theoretical results obtained
for the improved Gauss-Seidel method.
Abstract: Application of hulls processing technologies, based on high-concentrated energy sources (laser and plasma technologies), allow improve shipbuilding production. It is typical for high-speed vessels construction using steel and aluminum alloys with high precision hulls required. Report describes high-performance technologies for plasma welding (using direct current of reversed polarity), laser, and hybrid laser-arc welding of hulls structures developed by JSC “SSTC”
Abstract: High temperature deformation behavior of cast
Fe-20Cr-5Al alloy has been investigated in this study by performing
tensile and compression tests at temperatures from 1100 to 1200oC.
Rectangular ingots of which the dimensions were 300×300×100 in
millimeter were cast using vacuum induction melting. Phase
equilibrium was calculated using the FactSage®, thermodynamic
software and database. Tensile strength of cast Fe-20Cr-5Al alloy was
4 MPa at 1200oC. With temperature decreased, tensile strength
increased rapidly and reached up to 13 MPa at 1100oC. Elongation
also increased from 18 to 80% with temperature decreased from
1200oC to 1100oC. Microstructure observation revealed that M23C6
carbide was precipitated along the grain boundary and within the
matrix.
Abstract: In the present work, detailed analysis on flow characteristics of a pair of immiscible liquids through horizontal pipeline is simulated by using ANSYS FLUENT 6.2. Moderately viscous oil and water (viscosity ratio = 107, density ratio = 0.89 and interfacial tension = 0.024 N/m) have been taken as system fluids for the study. Volume of Fluid (VOF) method has been employed by assuming unsteady flow, immiscible liquid pair, constant liquid properties, and co-axial flow. Meshing has been done using GAMBIT. Quadrilateral mesh type has been chosen to account for the surface tension effect more accurately. From the grid independent study, we have selected 47037 number of mesh elements for the entire geometry. Simulation successfully predicts slug, stratified wavy, stratified mixed and annular flow, except dispersion of oil in water, and dispersion of water in oil. Simulation results are validated with horizontal literature data and good conformity is observed. Subsequently, we have simulated the hydrodynamics (viz., velocity profile, area average pressure across a cross section and volume fraction profile along the radius) of stratified wavy and annular flow at different phase velocities. The simulation results show that in the annular flow, total pressure of the mixture decreases with increase in oil velocity due to the fact that pipe cross section is completely wetted with water. Simulated oil volume fraction shows maximum at the centre in core annular flow, whereas, in stratified flow, maximum value appears at upper side of the pipeline. These results are in accord with the actual flow configuration. Our findings could be useful in designing pipeline for transportation of crude oil.
Abstract: There is an essential need for obtaining the mathematical representation of fish body undulations, which can be used for designing and building new innovative types of marine propulsion systems with less environmental impact. This research work presents a case study to derive the mathematical model for fish body movement. Observation and capturing image methods were used in this study in order to obtain a mathematical representation of Clariasbatrachus fish (catfish). An experiment was conducted by using an aquarium with dimension 0.609 m x 0.304 m x 0.304 m, and a 0.5 m ruler was attached at the base of the aquarium. Progressive Scan Monochrome Camera was positioned at 1.8 m above the base of the aquarium to provide swimming sequences. Seven points were marked on the fish body using white marker to indicate the fish movement and measuring the amplitude of undulation. Images from video recordings (20 frames/s) were analyzed frame by frame using local coordinate system, with time interval 0.05 s. The amplitudes of undulations were obtained for image analysis from each point that has been marked on fish body. A graph of amplitude of undulations versus time was plotted by using computer to derive a mathematical fit. The function for the graph is polynomial with nine orders.
Abstract: An extensive amount of work has been done in data
clustering research under the unsupervised learning technique in Data
Mining during the past two decades. Moreover, several approaches
and methods have been emerged focusing on clustering diverse data
types, features of cluster models and similarity rates of clusters.
However, none of the single clustering algorithm exemplifies its best
nature in extracting efficient clusters. Consequently, in order to
rectify this issue, a new challenging technique called Cluster
Ensemble method was bloomed. This new approach tends to be the
alternative method for the cluster analysis problem. The main
objective of the Cluster Ensemble is to aggregate the diverse
clustering solutions in such a way to attain accuracy and also to
improve the eminence the individual clustering algorithms. Due to
the massive and rapid development of new methods in the globe of
data mining, it is highly mandatory to scrutinize a vital analysis of
existing techniques and the future novelty. This paper shows the
comparative analysis of different cluster ensemble methods along
with their methodologies and salient features. Henceforth this
unambiguous analysis will be very useful for the society of clustering
experts and also helps in deciding the most appropriate one to resolve
the problem in hand.
Abstract: Metal matrix composites (MMCs) have gained a
considerable interest in the last three decades. Conventional powder
metallurgy production route often involves the addition of reinforcing
phases into the metal matrix directly, which leads to poor wetting
behavior between ceramic phase and metal matrix and the
segregation of reinforcements. The commonly used elements for
ceramic phase formation in iron based MMCs are Ti, Nb, Mo, W, V
and C, B. The aim of the present paper is to investigate the effect of
sintering temperature and V-B addition on densification, phase
development, microstructure, and hardness of Fe–V-B composites
(Fe-(5-10) wt. %B – 25 wt. %V alloys) prepared by powder
metallurgy process. Metal powder mixes were pressed uniaxial and
sintered at different temperatures (ranging from 1300 to 1400ºC) for
1h. The microstructure of the (V, B) Fe composites was studied with
the help of high magnification optical microscope and XRD.
Experimental results show that (V, B) Fe composites can be produced
by conventional powder metallurgy route.
Abstract: Advances in the field of image processing envision a
new era of evaluation techniques and application of procedures in
various different fields. One such field being considered is the
biomedical field for prognosis as well as diagnosis of diseases. This
plethora of methods though provides a wide range of options to select
from, it also proves confusion in selecting the apt process and also in
finding which one is more suitable. Our objective is to use a series of
techniques on bone scans, so as to detect the occurrence of
rheumatoid arthritis (RA) as accurately as possible. Amongst other
techniques existing in the field our proposed system tends to be more
effective as it depends on new methodologies that have been proved
to be better and more consistent than others. Computer aided
diagnosis will provide more accurate and infallible rate of
consistency that will help to improve the efficiency of the system.
The image first undergoes histogram smoothing and specification,
morphing operation, boundary detection by edge following algorithm
and finally image subtraction to determine the presence of
rheumatoid arthritis in a more efficient and effective way. Using preprocessing
noises are removed from images and using segmentation,
region of interest is found and Histogram smoothing is applied for a
specific portion of the images. Gray level co-occurrence matrix
(GLCM) features like Mean, Median, Energy, Correlation, Bone
Mineral Density (BMD) and etc. After finding all the features it
stores in the database. This dataset is trained with inflamed and noninflamed
values and with the help of neural network all the new
images are checked properly for their status and Rough set is
implemented for further reduction.
Abstract: Polymer composite nano-fibers including (1, 3 wt %)
silver nano-particles have been produced by electrospinning method.
Polyacrylonitrile/N,N-dimethylformamide (PAN/DMF) solution have
been prepared and the amount of silver nitrate have been adjusted to
PAN weight. Silver nano-particles were obtained from reduction of
silver ions into silver nano-particles by chemical reduction by
hydrazine hydroxide (N2H5OH). The different amount of silver salt
was loaded into polymer matrix to obtain polyacrylonitrile composite
nano-fiber containing silver nano-particles. The effect of the amount
of silver nano-particles on the properties of composite nano-fiber web
was investigated. Electrical conductivity, mechanical properties,
thermal properties were examined by Microtest LCR Meter 6370
(0.01 mΩ-100 MΩ), Tensile tester, Differential scanning calorimeter
DSC (Q10) and SEM respectively. Also antimicrobial efficiency test
(ASTM E2149-10) was done against to Staphylococcus aureus
bacteria. It has been seen that breaking strength, conductivity,
antimicrobial effect, enthalpy during cyclization increase by use of
silver nano-particles while the diameter of nano-fiber decreases.
Abstract: In recent years, many researchers are involved in the
field of fuzzy theory. However, there are still a lot of issues to be
resolved. Especially on topics related to controller design such as the
field of robot, artificial intelligence, and nonlinear systems etc.
Besides fuzzy theory, algorithms in swarm intelligence are also a
popular field for the researchers. In this paper, a concept of utilizing
one of the swarm intelligence method, which is called Bacterial-GA
Foraging, to find the stabilized common P matrix for the fuzzy
controller system is proposed. An example is given in in the paper, as
well.
Abstract: In this paper, we present a neural-network (NN) based
approach to represent a nonlinear Tagagi-Sugeno (T-S) system. A
linear differential inclusion (LDI) state-space representation is utilized
to deal with the NN models. Taking advantage of the LDI
representation, the stability conditions and controller design are
derived for a class of nonlinear structural systems. Moreover, the
concept of utilizing the Parallel Particle Swarm Optimization (PPSO)
algorithm to solve the common P matrix under the stability criteria is
given in this paper.
Abstract: In this paper, a fifth order propagator operators are proposed for estimating the Angles Of Arrival (AOA) of narrowband electromagnetic waves impinging on antenna array when its number of sensors is larger than the number of radiating sources.
The array response matrix is partitioned into five linearly dependent phases to construct the noise projector using five different propagators from non diagonal blocks of the spectral matrice of the received data; hence, five different estimators are proposed to estimate the angles of the sources. The simulation results proved the performance of the proposed estimators in the presence of white noise comparatively to high resolution eigen based spectra.
Abstract: In this paper, we investigated the effect of real valued transformation of the spectral matrix of the received data for Angles Of Arrival estimation problem. Indeed, the unitary transformation of Partial Propagator (UPP) for narrowband sources is proposed and applied on Uniform Linear Array (ULA).
Monte Carlo simulations proved the performance of the UPP spectrum comparatively with Forward Backward Partial Propagator (FBPP) and Unitary Propagator (UP). The results demonstrates that when some of the sources are fully correlated and closer than the Rayleigh angular limit resolution of the broadside array, the UPP method outperforms the FBPP in both of spatial resolution and complexity.