61,700 research outputs found
Speculative Thread Framework for Transient Management and Bumpless Transfer in Reconfigurable Digital Filters
There are many methods developed to mitigate transients induced when abruptly
changing dynamic algorithms such as those found in digital filters or
controllers. These "bumpless transfer" methods have a computational burden to
them and take time to implement, causing a delay in the desired switching time.
This paper develops a method that automatically reconfigures the computational
resources in order to implement a transient management method without any delay
in switching times. The method spawns a speculative thread when it predicts if
a switch in algorithms is imminent so that the calculations are done prior to
the switch being made. The software framework is described and experimental
results are shown for a switching between filters in a filter bank.Comment: 6 pages, 7 figures, to be presented at American Controls Conference
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Oscillation-based DFT for Second-order Bandpass OTA-C Filters
This document is the Accepted Manuscript version. Under embargo until 6 September 2018. The final publication is available at Springer via https://doi.org/10.1007/s00034-017-0648-9.This paper describes a design for testability technique for second-order bandpass operational transconductance amplifier and capacitor filters using an oscillation-based test topology. The oscillation-based test structure is a vectorless output test strategy easily extendable to built-in self-test. The proposed methodology converts filter under test into a quadrature oscillator using very simple techniques and measures the output frequency. Using feedback loops with nonlinear block, the filter-to-oscillator conversion techniques easily convert the bandpass OTA-C filter into an oscillator. With a minimum number of extra components, the proposed scheme requires a negligible area overhead. The validity of the proposed method has been verified using comparison between faulty and fault-free simulation results of Tow-Thomas and KHN OTA-C filters. Simulation results in 0.25ÎĽm CMOS technology show that the proposed oscillation-based test strategy for OTA-C filters is suitable for catastrophic and parametric faults testing and also effective in detecting single and multiple faults with high fault coverage.Peer reviewedFinal Accepted Versio
Dynamic reconfiguration technologies based on FPGA in software defined radio system
Partial Reconfiguration (PR) is a method for Field Programmable Gate Array (FPGA) designs which allows multiple applications to time-share a portion of an FPGA while the rest of the device continues to operate unaffected. Using this strategy, the physical layer processing architecture in Software Defined Radio (SDR) systems can benefit from reduced complexity and increased design flexibility, as different waveform applications can be grouped into one part of a single FPGA. Waveform switching often means not only changing functionality, but also changing the FPGA clock frequency. However, that is beyond the current functionality of PR processes as the clock components (such as Digital Clock Managers (DCMs)) are excluded from the process of partial reconfiguration. In this paper, we present a novel architecture that combines another reconfigurable technology, Dynamic Reconfigurable Port (DRP), with PR based on a single FPGA in order to dynamically change both functionality and also the clock frequency. The architecture is demonstrated to reduce hardware utilization significantly compared with standard, static FPGA design
Open-ended evolution to discover analogue circuits for beyond conventional applications
This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s10710-012-9163-8. Copyright @ Springer 2012.Analogue circuits synthesised by means of open-ended evolutionary algorithms often have unconventional designs. However, these circuits are typically highly compact, and the general nature of the evolutionary search methodology allows such designs to be used in many applications. Previous work on the evolutionary design of analogue circuits has focused on circuits that lie well within analogue application domain. In contrast, our paper considers the evolution of analogue circuits that are usually synthesised in digital logic. We have developed four computational circuits, two voltage distributor circuits and a time interval metre circuit. The approach, despite its simplicity, succeeds over the design tasks owing to the employment of substructure reuse and incremental evolution. Our findings expand the range of applications that are considered suitable for evolutionary electronics
Frequency and fundamental signal measurement algorithms for distributed control and protection applications
Increasing penetration of distributed generation within electricity networks leads to the requirement for cheap, integrated, protection and control systems. To minimise cost, algorithms for the measurement of AC voltage and current waveforms can be implemented on a single microcontroller, which also carries out other protection and control tasks, including communication and data logging. This limits the frame rate of the major algorithms, although analogue to digital converters (ADCs) can be oversampled using peripheral control processors on suitable microcontrollers. Measurement algorithms also have to be tolerant of poor power quality, which may arise within grid-connected or islanded (e.g. emergency, battlefield or marine) power system scenarios. This study presents a 'Clarke-FLL hybrid' architecture, which combines a three-phase Clarke transformation measurement with a frequency-locked loop (FLL). This hybrid contains suitable algorithms for the measurement of frequency, amplitude and phase within dynamic three-phase AC power systems. The Clarke-FLL hybrid is shown to be robust and accurate, with harmonic content up to and above 28% total harmonic distortion (THD), and with the major algorithms executing at only 500 samples per second. This is achieved by careful optimisation and cascaded use of exact-time averaging techniques, which prove to be useful at all stages of the measurements: from DC bias removal through low-sample-rate Fourier analysis to sub-harmonic ripple removal. Platform-independent algorithms for three-phase nodal power flow analysis are benchmarked on three processors, including the Infineon TC1796 microcontroller, on which only 10% of the 2000 mus frame time is required, leaving the remainder free for other algorithms
Output Filter Aware Optimization of the Noise Shaping Properties of {\Delta}{\Sigma} Modulators via Semi-Definite Programming
The Noise Transfer Function (NTF) of {\Delta}{\Sigma} modulators is typically
designed after the features of the input signal. We suggest that in many
applications, and notably those involving D/D and D/A conversion or actuation,
the NTF should instead be shaped after the properties of the
output/reconstruction filter. To this aim, we propose a framework for optimal
design based on the Kalman-Yakubovich-Popov (KYP) lemma and semi-definite
programming. Some examples illustrate how in practical cases the proposed
strategy can outperform more standard approaches.Comment: 14 pages, 18 figures, journal. Code accompanying the paper is
available at http://pydsm.googlecode.co
Performance and emissions of compression ignition engine fueled with preheated blend of vegetable oil
Now days fossil fuel has been a problem that can been use in a compression ignition
engine. Straight vegetable oil is one of the most reliable fuel that suitable for diesel
engine. The scope of study of this study is focused on performance and emission of
the straight vegetable oil from the grocery store to compare with crude palm oil from
UTHM pilot plan. S5, S10 and S15 straight vegetable oil fuel is used for this
experiment. This straight vegetable oil is also compared with an natural diesel in a
combustion-ignition engine. The test is conducted with UTHM dynomometer which
is located at automotive lab. The properties of the vegetable oil is tested for density, kinematic viscosity, water content, acids value and flash points. Brake power, flywheel torque, (in term of hydrocarbon, carbon monoxide, carbon dioxide, oxygen
content and smoke opacity) and tested for performance and emission. Results
obtained show that flywheel torque that has been produced from the biodiesel fuels
are less than the natural diesel (ND). Biodiesel emission results shown a better
emission compared to the ND fuels. The CO2, CO, HC and O2 content that released
from the biodiesel fuels are clearly lower than the ND fuels. At low engine speed, biodiesel smoke opacity contents are quite high produces compared to the OD and
other type o
A Multiproject Chip Approach to the Teaching of Analog MOS LSI and VLSI
Multiproject chip implementation has been used in teaching analog MOS circuit design. After having worked with computer simulation and layout aids in homework problems, students designed novel circuits including several high
performance op amps, an A/D converter, a switched capacitor filter, a 1 K dynamic RAM, and a variety of less conventional MOS circuits such as a VII converter, an AC/DC converter, an AM radio receiver, a digitally-controlled
analog signal processor, and on-chip circuitry for measuring transistor capacitances. These circuits were laid out as part of an NMOS multiproject chip. Several of the designs exhibit a considerable degree of innovation;
fabrication pending, computer simulation shows that some may be pushing the state of the art. Several designs are of interest to digital designers; in fact, the course has provided knowledge and technique needed for detailed
digital circuit design at the gate level
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