Abstract: This paper presents a model for the evaluation of
energy performance and aerodynamic forces acting on a three-bladed
small vertical axis Darrieus wind turbine depending on blade chord
curvature with respect to rotor axis.
The adopted survey methodology is based on an analytical code
coupled to a solid modeling software, capable of generating the
desired blade geometry depending on the blade design geometric
parameters, which is linked to a finite volume CFD code for the
calculation of rotor performance.
After describing and validating the model with experimental data,
the results of numerical simulations are proposed on the bases of two
different blade profile architectures, which are respectively
characterized by a straight chord and by a curved one, having a chord
radius equal to rotor external circumference. A CFD campaign of
analysis is completed for three blade-candidate airfoil sections, that is
the recently-developed DU 06-W-200 cambered blade profile, a
classical symmetrical NACA 0021 and its derived cambered airfoil,
characterized by a curved chord, having a chord radius equal to rotor
external circumference.
The effects of blade chord curvature on angle of attack, blade
tangential and normal forces are first investigated and then the
overall rotor torque and power are analyzed as a function of blade
azimuthal position, achieving a numerical quantification of the
influence of blade camber on overall rotor performance.
Abstract: Electrical distribution systems are incurring large losses as the loads are wide spread, inadequate reactive power compensation facilities and their improper control. A comprehensive static VAR compensator consisting of capacitor bank in five binary sequential steps in conjunction with a thyristor controlled reactor of smallest step size is employed in the investigative work. The work deals with the performance evaluation through analytical studies and practical implementation on an existing system. A fast acting error adaptive controller is developed suitable both for contactor and thyristor switched capacitors. The switching operations achieved are transient free, practically no need to provide inrush current limiting reactors, TCR size minimum providing small percentages of nontriplen harmonics, facilitates stepless variation of reactive power depending on load requirement so as maintain power factor near unity always. It is elegant, closed loop microcontroller system having the features of self regulation in adaptive mode for automatic adjustment. It is successfully tested on a distribution transformer of three phase 50 Hz, Dy11, 11KV/440V, 125 KVA capacity and the functional feasibility and technical soundness are established. The controller developed is new, adaptable to both LT & HT systems and practically established to be giving reliable performance.
Abstract: The electrical and structural properties of Hf/Al/Ni/Au
(20/100/25/50 nm) ohmic contact to n-GaN are reported in this study.
Specific contact resistivities of Hf/Al/Ni/Au based contacts have been
investigated as a function of annealing temperature and achieve the
lowest value of 1.09´10-6 Ω·cm2 after annealing at 650 oC in vacuum.
A detailed mechanism of ohmic contact formation is discussed. By
using different chemical analyses, it is anticipated that the formation of
Hf-Al-N alloy might be responsible to form low temperature ohmic
contacts for the Hf-based scheme to n-GaN.
Abstract: The aim of this research is to evaluate surface
roughness and develop a multiple regression model for surface roughness as a function of cutting parameters during the turning of
flame hardened medium carbon steel with TiN-Al2O3-TiCN coated inserts. An experimental plan of work and signal-to-noise ratio (S/N)
were used to relate the influence of turning parameters to the
workpiece surface finish utilizing Taguchi methodology. The effects
of turning parameters were studied by using the analysis of variance (ANOVA) method. Evaluated parameters were feed, cutting speed,
and depth of cut. It was found that the most significant interaction among the considered turning parameters was between depth of cut and feed. The average surface roughness (Ra) resulted by TiN-Al2O3-
TiCN coated inserts was about 2.44 μm and minimum value was 0.74 μm. In addition, the regression model was able to predict values for surface roughness in comparison with experimental values within
reasonable limit.
Abstract: The production of devices in nanoscale with specific
molecular rectifying function is one of the most significant goals in
state-of-art technology. In this work we show by ab initio quantum
mechanics calculations coupled with non-equilibrium Green
function, the design of an organic two-terminal device. These
molecular structures have molecular source and drain with several
bridge length (from five up to 11 double bonds). Our results are
consistent with significant features as a molecular rectifier and can be
raised up as: (a) it can be used as bi-directional symmetrical rectifier;
(b) two devices integrated in one (FET with one operational region,
and Thyristor thiristor); (c) Inherent stability due small intrinsic
capacitance under forward/reverse bias. We utilize a scheme for the
transport mechanism based on previous properties of ¤Ç bonds type
that can be successfully utilized to construct organic nanodevices.
Abstract: This paper presents a 24 watts SEPIC converter design
and control using microprocessor. SEPIC converter has advantages of
a wide input range and miniaturization caused by the low stress at
elements. There is also an advantage that the input and output are
isolated in MOSFET-off state. This paper presents the PID control
through the SEPIC converter transfer function using a DSP and the
protective circuit for fuel cell from the over-current and
inverse-voltage by using the characteristic of SEPIC converter. Then it
derives them through the experiments.
Abstract: The innovative fuzzy estimator is used to estimate the
ground motion acceleration of the retaining structure in this study. The
Kalman filter without the input term and the fuzzy weighting recursive
least square estimator are two main portions of this method. The
innovation vector can be produced by the Kalman filter, and be
applied to the fuzzy weighting recursive least square estimator to
estimate the acceleration input over time. The excellent performance
of this estimator is demonstrated by comparing it with the use of
difference weighting function, the distinct levels of the measurement
noise covariance and the initial process noise covariance. The
availability and the precision of the proposed method proposed in this
study can be verified by comparing the actual value and the one
obtained by numerical simulation.
Abstract: In this paper, we are presenting a new type of pointing interface for computers which provides mouse functionalities with near surface haptic feedback. Further, it can be configured as a haptic display where users may feel the basic geometrical shapes in the GUI by moving the finger on top of the device surface. These functionalities are achieved by tracking three dimensional positions of the neodymium magnet using Hall Effect sensors grid and generating like polarity haptic feedback using an electromagnet array. This interface brings the haptic sensations to the 3D space where previously it is felt only on top of the buttons of the haptic mouse implementations.
Abstract: Properly sized capacitor banks are connected across induction motors for several reasons including power factor correction, reducing distortions, increasing capacity, etc. Total harmonic distortion (THD) and power factor (PF) are used in such cases to quantify the improvements obtained through connection of the external capacitor banks. On the other hand, one of the methods for assessing the motor internal condition is by the use of Park-s pattern analysis. In spite of taking adequate precautionary measures, the capacitor banks may sometimes malfunction. Such a minor fault in the capacitor bank is often not apparently discernible. This may however, give rise to substantial degradation of power factor correction performance and may also damage the supply profile. The case is more severe with the fact that the Park-s pattern gets distorted due to such external capacitor faults, and can give anomalous results about motor internal fault analyses. The aim of this paper is to present simulation and hardware laboratory test results to have an understanding of the anomalies in harmonic distortion and Park-s pattern analyses in induction motors due to capacitor bank defects.
Abstract: Microstrip antennas are conformable to planar and
nonplanar surfaces, simple and inexpensive to fabricate using modern
printed-circuit technology. Circular polarization of low-profile
microstrip patch with high bandwidth is achieved in this research
through the use of a three-cross-arms branch-line coupler with
sequential rotated arrays, another low-profile antenna of hollow
cylinder is also proposed and the function of reconnaissance with
microstrip antenna on Mini UAV (unmanned aerial vehicle) are
evaluated in practical flight test.
Abstract: The running logs of a process hold valuable
information about its executed activity behavior and generated activity
logic structure. Theses informative logs can be extracted, analyzed and
utilized to improve the efficiencies of the process's execution and
conduction. One of the techniques used to accomplish the process
improvement is called as process mining. To mine similar processes is
such an improvement mission in process mining. Rather than directly
mining similar processes using a single comparing coefficient or a
complicate fitness function, this paper presents a simplified heuristic
process mining algorithm with two similarity comparisons that are
able to relatively conform the activity logic sequences (traces) of
mining processes with those of a normalized (regularized) one. The
relative process conformance is to find which of the mining processes
match the required activity sequences and relationships, further for
necessary and sufficient applications of the mined processes to process
improvements. One similarity presented is defined by the relationships
in terms of the number of similar activity sequences existing in
different processes; another similarity expresses the degree of the
similar (identical) activity sequences among the conforming processes.
Since these two similarities are with respect to certain typical behavior
(activity sequences) occurred in an entire process, the common
problems, such as the inappropriateness of an absolute comparison and
the incapability of an intrinsic information elicitation, which are often
appeared in other process conforming techniques, can be solved by the
relative process comparison presented in this paper. To demonstrate
the potentiality of the proposed algorithm, a numerical example is
illustrated.
Abstract: If an unsteady heat transfer or heat impulse happens in
part of the cryogenic pipeline system of large space environment
simulation equipment while running in vacuum environment, it will
lead to abnormal flow of the cryogenic fluid in the pipeline. When the
situation gets worse, the cryogenic fluid in the pipeline will have phase
change and a gas block which results in the malfunction of the
cryogenic pipeline system. Referring to the structural parameter of a
typical cryogenic pipeline system and the basic equation, an analytical
model and a calculation model for cryogenic pipeline system can be
built. The various factors which influence the thermal resistance of a
cryogenic pipeline system can be analyzed and calculated by using the
qualitative analysis relation deduced for thermal resistance of pipeline.
The research conclusion could provide theoretical support for the
design and operation of a cryogenic pipeline system
Abstract: This paper describes the design considerations of an
experimental setup for research and exploring the drives of batteryfed
electric vehicles. Effective setup composition and its components
are discussed. With experimental setup described in this paper,
durability and functional tests can be procured to the customers.
Multiple experiments are performed in the form of steady-state
system exploring, acceleration programs, multi-step tests (speed
control, torque control), load collectives or close-to-reality driving
tests (driving simulation). Main focus of the functional testing is on
the measurements of power and energy efficiency and investigations
in driving simulation mode, which are used for application purposes.
In order to enable the examination of the drive trains beyond
standard modes of operation, different other parameters can be
studied also.
Abstract: Two different superhydrophobic surfaces were
elaborated and their oil repellency behavior was evaluated using
several liquid with different surface tension. A silicone rubber/SiO2
nanocomposite coated (A) on aluminum substrate by “spin-coating"
and the sample B was an anodized aluminum surface covered by
Teflon-like coating. A high static contact angle about ∼162° was
measured for two prepared surfaces on which the water droplet rolloff.
Scanning electron microscopy (SEM) showed the presence of
micro/nanostructures for both sample A and B similar to that of lotus
leaf.
However the sample A presented significantly different behaviour
of wettability against the low surface tension liquid. Sample A has
been wetted totally by oil (dodecan) droplet while sample B showed
oleophobic behaviour. Oleophobic property of Teflon like coating
can be contributed to the presence of CF2 and CF3 functional group
which was shown by XPS analysis.
Abstract: This paper is concerned with the existence of a linear copositive Lyapunov function(LCLF) for a special class of switched positive linear systems(SPLSs) composed of continuousand discrete-time subsystems. Firstly, by using system matrices, we construct a special kind of matrices in appropriate manner. Secondly, our results reveal that the Hurwitz stability of these matrices is equivalent to the existence of a common LCLF for arbitrary finite sets composed of continuous- and discrete-time positive linear timeinvariant( LTI) systems. Finally, a simple example is provided to illustrate the implication of our results.
Abstract: In this paper, we proposed a method to design a
model-following adaptive controller for linear/nonlinear plants.
Radial basis function neural networks (RBF-NNs), which are known
for their stable learning capability and fast training, are used to
identify linear/nonlinear plants. Simulation results show that the
proposed method is effective in controlling both linear and nonlinear
plants with disturbance in the plant input.
Abstract: Although silicon photonic devices provide a significantly larger bandwidth and dissipate a substantially less power than the electronic devices, they suffer from a large size due to the fundamental diffraction limit and the weak optical response of Si. A potential solution is to exploit Si plasmonics, which may not only miniaturize the photonic device far beyond the diffraction limit, but also enhance the optical response in Si due to the electromagnetic field confinement. In this paper, we discuss and summarize the recently developed metal-insulator-Si-insulator-metal nanoplasmonic waveguide as well as various passive and active plasmonic components based on this waveguide, including coupler, bend, power splitter, ring resonator, MZI, modulator, detector, etc. All these plasmonic components are CMOS compatible and could be integrated with electronic and conventional dielectric photonic devices on the same SOI chip. More potential plasmonic devices as well as plasmonic nanocircuits with complex functionalities are also addressed.
Abstract: Human immunodeficiency virus infection and
acquired immunodeficiency syndrome is a global pandemic with
cases reporting from virtually every country and continues to be a
common infection in developing country like India.
Microalbuminuria is a manifestation of human immunodeficiency
virus associated nephropathy. Therefore, microalbuminuria may be
an early marker of human immunodeficiency virus associated
nephropathy, and screening for its presence may be beneficial. A
strikingly high prevalence of microalbuminuria among human
immunodeficiency virus infected patients has been described in
various studies. Risk factors for clinically significant proteinuria
include African - American race, higher human immunodeficiency
virus ribonucleic acid level and lower CD4 lymphocyte count. The
cardiovascular risk factors of increased systolic blood pressure and
increase fasting blood sugar level are strongly associated with
microalbuminuria in human immunodeficiency virus patient. These
results suggest that microalbuminuria may be a sign of current
endothelial dysfunction and micro-vascular disease and there is
substantial risk of future cardiovascular disease events. Positive
contributing factors include early kidney disease such as human
immunodeficiency virus associated nephropathy, a marker of end
organ damage related to co morbidities of diabetes or hypertension,
or more diffuse endothelial cells dysfunction. Nevertheless after
adjustment for non human immunodeficiency virus factors, human
immunodeficiency virus itself is a major risk factor. The presence of
human immunodeficiency virus infection is independent risk to
develop microalbuminuria in human immunodeficiency virus patient.
Cardiovascular risk factors appeared to be stronger predictors of
microalbuminuria than markers of human immunodeficiency virus
severity person with human immunodeficiency virus infection and
microalbuminuria therefore appear to potentially bear the burden of
two separate damage related to known vascular end organ damage
related to know vascular risk factors, and human immunodeficiency
virus specific processes such as the direct viral infection of kidney
cells.The higher prevalence of microalbuminuria among the human
immunodeficiency virus infected could be harbinger of future
increased risks of both kidney and cardiovascular disease. Further
study defining the prognostic significance of microalbuminuria
among human immunodeficiency virus infected persons will be
essential. Microalbuminuria seems to be a predictor of cardiovascular
disease in diabetic and non diabetic subjects, hence it can also be
used for early detection of micro vascular disease in human
immunodeficiency virus positive patients, thus can help to diagnose
the disease at the earliest.
Abstract: The nickel and gold nanoclusters as supported
catalysts were analyzed by XAS, XRD and XPS in order to
determine their local, global and electronic structure. The present
study has pointed out a strong deformation of the local structure of
the metal, due to its interaction with oxide supports. The average
particle size, the mean squares of the microstrain, the particle size
distribution and microstrain functions of the supported Ni and Au
catalysts were determined by XRD method using Generalized Fermi
Function for the X-ray line profiles approximation. Based on EXAFS
analysis we consider that the local structure of the investigated
systems is strongly distorted concerning the atomic number pairs.
Metal-support interaction is confirmed by the shape changes of the
probability densities of electron transitions: Ni K edge (1s →
continuum and 2p), Au LIII-edge (2p3/2 → continuum, 6s, 6d5/2 and
6d3/2). XPS investigations confirm the metal-support interaction at
their interface.
Abstract: Optimal capacitor allocation in distribution systems
has been studied for a long times. It is an optimization problem
which has an objective to define the optimal sizes and locations of
capacitors to be installed. In this works, an overview of capacitor
placement problem in distribution systems is briefly introduced. The
objective functions and constraints of the problem are listed and the
methodologies for solving the problem are summarized.