403,789 research outputs found
Control strategy for switched reluctance motor with rotary encoder based rotor position detection
Development of electric drive tends to the use of Switched Reluctance Motor (SRM) for their advantages and green technology issues. The SRM takes significant place in development for its simplicity, robust construction, and low cost. Sensorless method can be applied to drive SRM, it is less expansive but has more complexity and limitation. On the other hand, although sensor-based rotor position detection needs a hardware assembled on the shaft, some advantages can be obtained. In this paper, a control strategy for SRM drive with rotary encoder based rotor position detection is proposed, core of the strategy implements digital signal controller. The problem associated with wide range speed and standstill operation can be overcome by this strategy. This is also capable to vary the time to turn the switches on and off by software. The analysis was verified by simulations and experiments
Control of the weakly damped System with the embedded system support
This paper deals with the experimental verification of the importance of embedded systems with an applied MEMS sensor in controlling weakly damped systems. The aim is to suppress actively residual oscillations. The model of a planar physical pendulum with a prismatic joint was chosen for the experiment. The sensor made by MEMS technology, in which three-axis gyroscope and three-axis accelerometer are integrated, has been used for sensing the angle of deflection of the load from the equilibrium position. The simulation model represents the crane arm with a moving carriag
On application of least-delay variation problem in ethernet networks using SDN concept
The goal of this paper is to present an application idea of SDN in Smart Grids, particularly, in the area of L2 multicast as defined by IEC 61850-9-2. Authors propose an Integer Linear Formulation (ILP) dealing with a Least-Delay-Variation multicast forwarding problem that has a potential to utilize Ethernet networks in a new way. The proposed ILP formulation is numerically evaluated on random graph topologies and results are compared to a shortest path tree approach that is traditionally a product of Spanning Tree Protocols. Results confirm the correctness of the ILP formulation and illustrate dependency of a solution quality on the selected graph models, especially, in a case of scale-free topologies
An investigation of planar array system artefacts generated within an electrical impedance mammography system developed for breast cancer detection
An Electrical Impedance Mammography (EIM) planar array imaging system is being developed at the University of Sussex for the detection of breast cancers. Investigations have shown that during data collection, systematic errors and patient artefacts are frequently introduced during signal acquisition from different electrodes pairs. This is caused, in particular, by the large variations in the electrode-skin contact interface conditions occurring between separate electrode positions both with the same and different patients. As a result, the EIM image quality is seriously affected by these errors. Hence, this research aims to experimentally identify, analyse and propose effective methods to reduce the systematic errors at the electrode-skin interface. Experimental studies and subsequent analysis is presented to determine what ratio of electrode blockage seriously affects the acquired raw data which may in turn compromise the reconstruction. This leads to techniques for the fast and accurate detection of any such occurrences. These methodologies can be applied to any planar array based EIM system
TEM Study of High-Temperature Precipitation of Delta Phase in Inconel 718 Alloy
Inconel 718 is widely used because of its ability to retain strength at up to 650◦C for long periods of time through coherent metastable γ” Ni3Nb precipitation associated with a smaller volume fraction of γ’ Ni3Al precipitates. At very long ageing times at service temperature, γ” decomposes to the stable Ni3Nb δ phase. This latter phase is also present above the γ” solvus and is used for grain control during forging of alloy 718.While most works available on δ precipitation have been performed at temperatures below the γ” solvus, it appeared of interest to also investigate the case where δ phase precipitates directly fromthe fccmatrix free of γ’’precipitates. This was studied by X-ray diffraction and transmission electron microscopy (TEM). TEM observations confirmed the presence of rotation-ordered domains in δ plates, and some unexpected contrast could be explained by double diffraction due to overlapping phases
Geometric Modeling of Cellular Materials for Additive Manufacturing in Biomedical Field: A Review
Advances in additive manufacturing technologies facilitate the fabrication of cellular materials that have tailored functional characteristics. The application of solid freeform fabrication techniques is especially exploited in designing scaffolds for tissue engineering. In this review, firstly, a classification of cellular materials from a geometric point of view is proposed; then, the main approaches on geometric modeling of cellular materials are discussed. Finally, an investigation on porous scaffolds fabricated by additive manufacturing technologies is pointed out. Perspectives in geometric modeling of scaffolds for tissue engineering are also proposed
Transmission transparency and potential convergence of optical network solutions at the physical layer for bit rates from 2.5 Gb·s-1 to 256 Gb·s-1
In this paper, we investigate optical network
recommendations GPON and XG-PON with triple-play
services in terms of physical reach, number of subscribers,
transceiver design, modulation format and implementation
cost. Despite trends to increase the bit
rate from 2.5 Gb s1 to 10 Gb s1 and beyond, TDMPONs
cannot cope with bandwidth requirements of future
networks. TDM and WDM techniques can be combined,
resulting in improved scalability. Longer physical
reach can be achieved by deploying active network
elements within the transmission path. We investigate
these options by considering their potential coexistence
at the physical layer. Subsequently, we analyse the upgrade
of optical channels to 100 Gb s1 and 256 Gb s1
by using advanced modulation formats, which combine
polarization division multiplexing with coherent detection
and digital signal processing. We show that PDMQPSK
format is suitable for 100 Gb s1 systems and
PDM-16QAM is more beneficial at 256 Gb s1. Simulations
are performed in the OptSim software environment
Software Engineering Timeline: major areas of interest and multidisciplinary trends
Ingeniería del software. EvolucionSociety today cannot run without software and by extension, without Software Engineering. Since this discipline emerged in 1968, practitioners have learned valuable lessons that have contributed to current practices. Some have become outdated but many are still relevant and widely used. From the personal and incomplete perspective of the authors, this paper not only reviews the major milestones and areas of interest in the Software Engineering timeline helping software engineers to appreciate the state of things, but also tries to give some insights into the trends that this complex engineering will see in the near future
Research and Education in Computational Science and Engineering
Over the past two decades the field of computational science and engineering
(CSE) has penetrated both basic and applied research in academia, industry, and
laboratories to advance discovery, optimize systems, support decision-makers,
and educate the scientific and engineering workforce. Informed by centuries of
theory and experiment, CSE performs computational experiments to answer
questions that neither theory nor experiment alone is equipped to answer. CSE
provides scientists and engineers of all persuasions with algorithmic
inventions and software systems that transcend disciplines and scales. Carried
on a wave of digital technology, CSE brings the power of parallelism to bear on
troves of data. Mathematics-based advanced computing has become a prevalent
means of discovery and innovation in essentially all areas of science,
engineering, technology, and society; and the CSE community is at the core of
this transformation. However, a combination of disruptive
developments---including the architectural complexity of extreme-scale
computing, the data revolution that engulfs the planet, and the specialization
required to follow the applications to new frontiers---is redefining the scope
and reach of the CSE endeavor. This report describes the rapid expansion of CSE
and the challenges to sustaining its bold advances. The report also presents
strategies and directions for CSE research and education for the next decade.Comment: Major revision, to appear in SIAM Revie
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