Abstract: In this paper, a low-power digital controller for DC-DC power conversion was presented. The controller generates the pulse-width modulated (PWM) signal from digital inputs provided by analog-to-digital converter (ADC). An efficient and simple design scheme to develop the control unit was discussed. This method allows minimization of the consumed resources of the chip and it is based on direct digital design approach. In this application, with the proposed scheme, nearly half area and two-third of the power consumption was saved compared to the conventional schemes. This work illustrates the possibility of implementing low-power and area-efficient power management circuit using direct digital design based approach.
Abstract: HfOx based Resistive Random Access Memory (RRAM) is one of the most widely studied material stack due to its promising performances as an emerging memory technology. In this work, we systematically investigated the effect of metal capping layer by preparing sample devices with varying thickness of Ti cap and comparing their operating parameters with the help of an Agilent-B1500A analyzer.
Abstract: Resistive Random Access Memory (RRAM) had received great amount of attention from various research efforts in recent years, owing to its promising performance as a next generation memory device. In this paper, samples based on TiN/HfOx/Pt stack were prepared and its electrical switching behaviors were characterized and discussed in brief.
Abstract: The performance of the Optical Code Division Multiplexing/ Wavelength Division Multiplexing (WDM/OCDM) technique for Optical Packet Switch is investigated. The impact on the performance of the impairment due to both Multiple Access Interference and Beat noise is studied. The Packet Loss Probability due to output packet contentions is evaluated as a function of the main switch and traffic parameters when Gold coherent optical codes are adopted. The Packet Loss Probability of the OCDM/WDM switch can reach 10-9 when M=16 wavelengths, Gold code of length L=511 and only 24 wavelength converters are used in the switch.
Abstract: We evaluate the average energy consumption per bit
in Optical Packet Switches equipped with BENES switching fabric
realized in Semiconductor Optical Amplifier (SOA) technology. We
also study the impact that the Amplifier Spontaneous Emission
(ASE) noise generated by a transmission system has on the power
consumption of the BENES switches due to the gain saturation of the
SOAs used to realize the switching fabric. As a matter of example for
32×32 switches supporting 64 wavelengths and offered traffic equal
to 0,8, the average energy consumption per bit is 2, 34 · 10-1 nJ/bit
and increases if ASE noise introduced by the transmission systems
is increased.
Abstract: This paper studies the effect of time delay on stability
of mutualism population model with limited resources for both
species. First, the stability of the model without time delay is
analyzed. The model is then improved by considering a time delay in
the mechanism of the growth rate of the population. We analyze the
effect of time delay on the stability of the stable equilibrium point.
Result showed that the time delay can induce instability of the stable
equilibrium point, bifurcation and stability switches.
Abstract: This paper proposes an adaptive sliding mode
controller which combines adaptive control and sliding
mode control to control a nonlinear robotic manipulator
with uncertain parameters. We use an adaptive algorithm
based on the concept of sliding mode control to alleviate the
chattering phenomenon of control input. Adaptive laws are
developed to obtain the gain of switching input and the
boundary layer parameters. The stability and convergence
of the robotic manipulator control system are guaranteed
by applying the Lyapunov theorem. Simulation results
demonstrate that the chattering of control input can be
alleviated effectively. The proposed controller scheme can
assure robustness against a large class of uncertainties and
achieve good trajectory tracking performance.
Abstract: In this study we present the effect of elevated
temperatures from 300K to 400K on the electrical properties of
copper Phthalocyanine (CuPc) based organic field effect transistors
(OFET). Thin films of organic semiconductor CuPc (40nm) and
semitransparent Al (20nm) were deposited in sequence, by vacuum
evaporation on a glass substrate with previously deposited Ag source
and drain electrodes with a gap of 40 μm. Under resistive mode of
operation, where gate was suspended it was observed that drain
current of this organic field effect transistor (OFET) show an
increase with temperature. While in grounded gate condition metal
(aluminum) – semiconductor (Copper Phthalocyanine) Schottky
junction dominated the output characteristics and device showed
switching effect from low to high conduction states like Zener diode
at higher bias voltages. This threshold voltage for switching effect
has been found to be inversely proportional to temperature and shows
an abrupt decrease after knee temperature of 360K. Change in
dynamic resistance (Rd = dV/dI) with respect to temperature was
observed to be -1%/K.
Abstract: Prediction of sinusoidal signals with time-varying
frequencies has been an important research topic in power electronics
systems. To solve this problem, we propose a new fuzzy
predictive filtering scheme, which is based on a Finite Impulse
Response (FIR) filter bank. Fuzzy logic is introduced here to provide
appropriate interpolation of individual filter outputs. Therefore,
instead of regular 'hard' switching, our method has the advantageous
'soft' switching among different filters. Simulation
comparisons between the fuzzy predictive filtering and conventional
filter bank-based approach are made to demonstrate that the
new scheme can achieve an enhanced prediction performance for
slowly changing sinusoidal input signals.
Abstract: Strict stability can present the rate of decay of the
solution, so more and more investigators are beginning to study the
topic and some results have been obtained. However, there are few
results about strict stability of stochastic differential equations. In
this paper, using Lyapunov functions and Razumikhin technique, we
have gotten some criteria for the strict stability of impulsive stochastic
functional differential equations with markovian switching.
Abstract: In this study, the performance of a high-frequency arc
welding machine including a two-switch inverter is analyzed. The
control of the system is achieved using two different control
techniques i- fuzzy logic control (FLC) ii- state space averaging
based sliding control. Fuzzy logic control does not need accurate
mathematical model of a plant and can be used in nonlinear
applications. The second method needs the mathematical model of
the system. In this method the state space equations of the system are
derived for two different “on" and “off" states of the switches. The
derived state equations are combined with the sliding control rule
considering the duty-cycle of the converter. The performance of the
system is analyzed by simulating the system using SIMULINK tool
box of MATLAB. The simulation results show that fuzzy logic
controller is more robust and less sensitive to parameter variations.
Abstract: This paper will present the implementation of QoS
policy based system by utilizing rules on Access Control List (ACL)
over Layer 3 (L3) switch. Also presented is the architecture on that
implementation; the tools being used and the result were gathered.
The system architecture has an ability to control ACL rules which are
installed inside an external L3 switch. ACL rules used to instruct the
way of access control being executed, in order to entertain all traffics
through that particular switch. The main advantage of using this
approach is that the single point of failure could be prevented when
there are any changes on ACL rules inside L3 switches. Another
advantage is that the agent could instruct ACL rules automatically
straight away based on the changes occur on policy database without
configuring them one by one. Other than that, when QoS policy
based system was implemented in distributed environment, the
monitoring process can be synchronized easily due to the automate
process running by agent over external policy devices.
Abstract: A high-linearity and high-speed current-mode sampleand-
hold circuit is designed and simulated using a 0.25μm CMOS
technology. This circuit design is based on low voltage and it utilizes
a fully differential circuit. Due to the use of only two switches the
switch related noise has been reduced. Signal - dependent -error is
completely eliminated by a new zero voltage switching technique.
The circuit has a linearity error equal to ±0.05μa, i.e. 12-bit
accuracy with a ±160 μa differential output - input signal frequency
of 5MHZ, and sampling frequency of 100 MHZ. Third
harmonic is equal to –78dB.
Abstract: This paper considers the robust exponential stability issues for a class of uncertain switched neutral system which delays switched according to the switching rule. The system under consideration includes both stable and unstable subsystems. The uncertainties considered in this paper are norm bounded, and possibly time varying. Based on multiple Lyapunov functional approach and dwell-time technique, the time-dependent switching rule is designed depend on the so-called average dwell time of stable subsystems as well as the ratio of the total activation time of stable subsystems and unstable subsystems. It is shown that by suitably controlling the switching between the stable and unstable modes, the robust stabilization of the switched uncertain neutral systems can be achieved. Two simulation examples are given to demonstrate the effectiveness of the proposed method.
Abstract: Flow field around hypersonic vehicles is very
complex and difficult to simulate. The boundary layers are squeezed
between shock layer and body surface. Resolution of boundary layer,
shock wave and turbulent regions where the flow field has high
values is difficult of capture. Detached eddy simulation (DES) is a
modification of a RANS model in which the model switches to a
subgrid scale formulation in regions fine enough for LES
calculations. Regions near solid body boundaries and where the
turbulent length scale is less than the maximum grid dimension are
assigned the RANS mode of solution. As the turbulent length scale
exceeds the grid dimension, the regions are solved using the LES
mode. Therefore the grid resolution is not as demanding as pure LES,
thereby considerably cutting down the cost of the computation. In
this research study hypersonic flow is simulated at Mach 8 and
different angle of attacks to resolve the proper boundary layers and
discontinuities. The flow is also simulated in the long wake regions.
Mesh is little different than RANS simulations and it is made dense
near the boundary layers and in the wake regions to resolve it
properly. Hypersonic blunt cone cylinder body with frustrum at angle
5o and 10 o are simulated and there aerodynamics study is performed
to calculate aerodynamics characteristics of different geometries. The
results and then compared with experimental as well as with some
turbulence model (SA Model). The results achieved with DES
simulation have very good resolution as well as have excellent
agreement with experimental and available data. Unsteady
simulations are performed for DES calculations by using duel time
stepping method or implicit time stepping. The simulations are
performed at Mach number 8 and angle of attack from 0o to 10o for
all these cases. The results and resolutions for DES model found
much better than SA turbulence model.
Abstract: Accurate modeling of high speed RLC interconnects
has become a necessity to address signal integrity issues in current
VLSI design. To accurately model a dispersive system of interconnects
at higher frequencies; a full-wave analysis is required.
However, conventional circuit simulation of interconnects with full
wave models is extremely CPU expensive. We present an algorithm
for reducing large VLSI circuits to much smaller ones with similar
input-output behavior. A key feature of our method, called Frequency
Shift Technique, is that it is capable of reducing linear time-varying
systems. This enables it to capture frequency-translation and sampling
behavior, important in communication subsystems such as mixers,
RF components and switched-capacitor filters. Reduction is obtained
by projecting the original system described by linear differential
equations into a lower dimension. Experiments have been carried out
using Cadence Design Simulator cwhich indicates that the proposed
technique achieves more % reduction with less CPU time than the
other model order reduction techniques existing in literature. We
also present applications to RF circuit subsystems, obtaining size
reductions and evaluation speedups of orders of magnitude with
insignificant loss of accuracy.
Abstract: Removing noise from the any processed images is very important. Noise should be removed in such a way that important information of image should be preserved. A decisionbased nonlinear algorithm for elimination of band lines, drop lines, mark, band lost and impulses in images is presented in this paper. The algorithm performs two simultaneous operations, namely, detection of corrupted pixels and evaluation of new pixels for replacing the corrupted pixels. Removal of these artifacts is achieved without damaging edges and details. However, the restricted window size renders median operation less effective whenever noise is excessive in that case the proposed algorithm automatically switches to mean filtering. The performance of the algorithm is analyzed in terms of Mean Square Error [MSE], Peak-Signal-to-Noise Ratio [PSNR], Signal-to-Noise Ratio Improved [SNRI], Percentage Of Noise Attenuated [PONA], and Percentage Of Spoiled Pixels [POSP]. This is compared with standard algorithms already in use and improved performance of the proposed algorithm is presented. The advantage of the proposed algorithm is that a single algorithm can replace several independent algorithms which are required for removal of different artifacts.
Abstract: Using Internet communication, new home electronics
have functions of monitoring and control from remote. However in
many case these electronics work as standalone, and old electronics
are not followed. Then, we developed the total remote system include
not only new electronics but olds. This systems node is a adapter of
electrical power plug that embed relay switch and some sensors, and
these nodes communicate with each other. the system server was build
on the Internet, and users access to this system from web browsers.
To reduce the cost to set up of this system, communication between
adapters are used ZigBee wireless network instead of wired LAN
cable[3]. From measured RSSI(received signal strength indicator)
information between each nodes, the system can estimate roughly
adapters were mounted on which room, and where in the room. So
also it reduces the cost of mapping nodes. Using this system, energy
saving and house monitoring are expected.
Abstract: Today, design requirements are extending more and
more from electronic (analogue and digital) to multidiscipline design.
These current needs imply implementation of methodologies to make
the CAD product reliable in order to improve time to market, study
costs, reusability and reliability of the design process.
This paper proposes a high level design approach applied for the
characterization and the optimization of Switched-Current Sigma-
Delta Modulators. It uses the new hardware description language
VHDL-AMS to help the designers to optimize the characteristics of
the modulator at a high level with a considerably reduced CPU time
before passing to a transistor level characterization.
Abstract: This work is a proposed model of CMOS for which
the algorithm has been created and then the performance evaluation
of this proposition has been done. In this context, another commonly
used model called ZSTT (Zero Switching Time Transient) model is
chosen to compare all the vital features and the results for the
Proposed Equivalent CMOS are promising. In the end, the excerpts
of the created algorithm are also included