618 research outputs found
Integral-derivative (I-D) and modulation-index-curve prediction control techniques for three-phase AC-DC buck-type converter with simplified voltage-based SPWM /Azrita Alias
No full textThis thesis presents the design of a three-phase AC-DC buck-type converter with bidirectional capability using simplified voltage-based sinusoidal pulse-width-modulation (SPWM) switching technique. With its four diodes connected to the switch enable bidirectional power flow in each switch. The proposed topology is an extension of the conventional 6-switch three-phase AC-DC buck-type converter whereas the proposed switching technique is a simplification of conventional modified SPWM technique. It uses one reference signals (0-60° sine wave) and one type carrier signal, instead of two reference signals and two types of carrier signals to generate PWM signals. The proposed circuit configuration produces sinusoidal AC current with low THD at near unity power factor using simplified voltage-based SPWM. Voltage feedback control allows high dynamic performance of the DC output voltage in the step-changing of reference and disturbance. Two digital feedback voltage controls, Integral-Derivative (I-D) and modulation-index-curve prediction techniques, are suggested to equalize the output voltage to the reference voltage with high dynamic performance and simpler implementation. The algorithm of the modulation-index-curve prediction technique is obtained through I-D control model by determining closed-loop dominant poles. By assuming zero system loss, a small steady-state error is still present (absent in the I-D controller). Modulation-index-curve-prediction technique is still advantageous because it reduces dependence on feedback-sensor reading and simplifies the I-D algorithms. The converter’s validity, PWM switching strategy, and feedback control strategy have been verified by simulation using MATLAB/Simulink. The hardware prototype has been implemented in a TMS320F28335 Digital Signal Processor (DSP) and the results are validated
Pushing Alias Resolution to the Limit
No full textIn this paper, we show that utilizing multiple protocols offers a unique opportunity to improve IP alias resolution and dual-stack inference substantially. Our key observation is that prevalent protocols, e.g., SSH and BGP, reply to unsolicited requests with a set of values that can be combined to form a unique device identifier. More importantly, this is possible by just completing the TCP hand-shake. Our empirical study shows that utilizing readily available scans and our active measurements can double the discovered IPv4 alias sets and more than 30× the dual-stack sets compared to the state-of-the-art techniques. We provide insights into our method's accuracy and performance compared to popular techniques.Cyber Securit
Mass flow visualization of solid particles in pneumatic pipelines using electrodynamic tomography system
No full textA Single-Input Single-Output Approach by using Minor-Loop Voltage Feedback Compensation with Modified SPWM Technique for Three-Phase AC–DC Buck Converter
No full textThe modified sinusoidal pulse-width modulation (SPWM) is one of the PWM techniques used in three-phase AC–DC buck
converters. The modified SPWM works without the current sensor (the converter is current sensorless), improves production of
sinusoidal AC current, enables obtainment of near-unity power factor, and controls output voltage through modulation gain
(ranging from 0 to 1). The main problem of the modified SPWM is the huge starting current and voltage (during transient) that
results from a large step change from the reference voltage. When the load changes, the output voltage significantly drops
(through switching losses and non-ideal converter elements). The single-input single-output (SISO) approach with minor-loop
voltage feedback controller presented here overcomes this problem. This approach is created on a theoretical linear model and
verified by discrete-model simulation on MATLAB/Simulink. The capability and effectiveness of the SISO approach in
compensating start-up current/voltage and in achieving zero steady-state error were tested for transient cases with step-changed
load and step-changed reference voltage for linear and non-linear loads. Tests were done to analyze the transient performance
against various controller gains. An experiment prototype was also developed for verification
An alias of I
No full textAn Alias of I is a manuscript of poems that emerge from familial myth into the sensoria and materiality of the Anthropocene, expanding from claustrophobic New Jersey suburbia to ancestral and rented homes in Malacca, Hong Kong, New York, California, and elsewhere. Blending temporality and locality, these movements through space incite explorations of the self, parsing consciousness, interiority, and perception. These poems reckon with inherited violence and the throughline of colonialism, immigration, and intergenerational trauma.
An Alias of I investigates identity and inheritance through the lens of queerness, neurodivergence, and Asian American diaspora. At once familiar and alien, these poems render modernity and selfhood into a landscape where the boundaries between bodies, environments, and stories—past and present—all blur. These meditations on trauma, loss, and mundanity reveal new possibilities that materialize through joy, intimacy, and found signs. An Alias of I embraces hybrid forms, blending prose, lyric, visual, and narrative poems, to explore emotional processing and rationalization through various angles and perspectives, attempting to capture the movement—focus points, detours, ruminations—of an evasive mind working toward an end.
As the title insinuates, the poems interrogate the mutability and instability of personhood. Through these poems, readers are asked to reckon with the gap between externality—who they want to be, how they want to be perceived, desires—and the internal, elusive self. From this tension emerges the difficulty and transcendence of intimacy and community. These poems guide readers through these spaces and worlds with humor, nonchalance and a sense of possibility, inviting readers to keep an open eye.M.F.A.Includes bibliographical reference
Two Steps Forward, One Step Back: The Selling of Charlie\u27S Angels and Alias
No full textThe author analyzes various elements of the promotional campaigns for two recent female-driven action narratives, the film Charlie\u27s Angels and the television series Alias. The analysis suggests that these inconsistent and often regressive campaigns weaken the potentially progressive gender images offered by the film and series
Using N-gram Analysis for Forensic Author Identification and Text Relatedness
No full textAM Session
Using N-gram Analysis for Forensic Author Identification and Text Relatedness
Carole Chaski, ALIAS Technology LLC and Institute for Linguistic Evidence, Inc, US
Dynamic load balancing for petascale quantum Monte Carlo applications: The Alias method
No full textDiffusion Monte Carlo is a highly accurate Quantum Monte Carlo method for electronic structure calculations of materials, but it requires frequent load balancing or population redistribution steps to maintain efficiency on parallel machines. This step can be a significant factor affecting performance, and will become more important as the number of processing elements increases. We propose a new dynamic load balancing algorithm, the Alias Method, and evaluate it theoretically and empirically. An important feature of the new algorithm is that the load can be perfectly balanced with each process receiving at most one message. It is also optimal in the maximum size of messages received by any process. We also optimize its implementation to reduce network contention, a process facilitated by the low messaging requirement of the algorithm: a simple renumbering of the MPI ranks based on proximity and a space filling curve significantly improves the MPI Allgather performance. Empirical results on the petaflop Cray XT Jaguar supercomputer at ORNL show up to 30% improvement in performance on 120,000 cores. The load balancing algorithm may be straightforwardly implemented in existing codes. The algorithm may also be employed by any method with many near identical computational tasks that require load balancing.Journal ArticlePublishe
A 3D LADM prototype implementation in INTERLIS
No full textThe massive developments and uses of high-rise buildings indicate that the demand for use of space above and below the ground surface is rapidly increasing in recent years. The same applies to Greece, where the existing cadastral model does not cover the 3D needs and does not conform to international standards. In this paper, a model is proposed, considered as an effort for overcoming these shortcomings, based on international standards, including the representation of a wide range of different types of spatial units, organized in levels according to the LA_Level structure of ISO19152 LADM. It is a proposal for a comprehensive multipurpose LAS supporting 2D and 3D cadastral registration in Greece. A prototype system was developed to exploit the strengths and limitations of the proposed conceptual model, as well as to investigate the efficiency of technological tools. Experience from the prototype will be used to further improve the conceptual model. The steps that were followed were: the description of the prototype in UML diagrams, the implementation via INTERLIS, a Swiss standard modeling language for geodata exchange, the selection of the most appropriate technical model/format to implement and visualize the result in 3D environment and finally the conversion and/or creation of sample data into the model. In this paper it is explored how INTERLIS can be used in actual implementation of land administration system based on LADM. During the development of the prototype many design decision have been taken and these are then analyzed, together with technical problems and challenges for future work.OLD Department of GIS Technolog
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