Search results for "switching"
showing 10 items of 288 documents
New approach for harmonic mitigation in single-phase five-level CHBMI with fundamental frequency switching
2017
The main objective of this paper is to study and analyse the voltage output waveform of a multilevel inverter, to suggest a new approach for harmonic mitigation improving the converter performance. These last type of converters represent a new technology in the field of DC/AC electrical energy conversion, presenting advantages respect to the traditional converters. In fact, the multilevel power converters present a low harmonic content and a high voltage level. The paper considers a five-level single-phase cascaded H-bridge inverter and fundamental frequency modulation techniques. The voltage waveform analysis has allowed to identify a working area of the converter where there are lowest va…
Aggregated Packet Transmission in Duty-Cycled WSNs: Modeling and Performance Evaluation
2017
[EN] Duty cycling (DC) is a popular technique for energy conservation in wireless sensor networks (WSNs) that allows nodes to wake up and sleep periodically. Typically, a single-packet transmission (SPT) occurs per cycle, leading to possibly long delay. With aggregated packet transmission (APT), nodes transmit a batch of packets in a single cycle. The potential benefits brought by an APT scheme include shorter delay, higher throughput, and higher energy efficiency. In the literature, different analytical models have been proposed to evaluate the performance of SPT schemes. However, no analytical models for the APT mode on synchronous DC medium access control (MAC) mechanisms exist. In this …
A structured filter for Markovian switching systems
2014
In this work, a new methodology for the structuring of multiple model estimation schemas is developed. The proposed filter is applied to the estimation and detection of active mode in dynamic systems. The discrete-time Markovian switching systems represented by several linear models, associated with a particular operating mode, are studied. Therefore, the main idea of this work is the subdivision of the models set to some subsets in order to improve the detection and estimation performances. Each subset is associated with sub-estimators based on models of the subset. In order to compute the global estimate and subset probabilities, a global estimator is proposed. Theoretical developments ba…
As much English as possible : A study on two secondary school English teachers language use and the motives behind their language choices
2009
Kommunikatiivisen kompetenssin ja suullisen kielitaidon painoarvo vieraiden kielten oppimisessa ja opettamisessa on kasvanut viime vuosina, mikä on lisännyt huomiota myös opettajien kielenkäyttöön. Tämän proseminaaritutkimuksen tarkoituksena oli selvittää, minkä verran englannin opettajat käyttävät tunneillaan englantia ja suomea ja miten he perustelevat kielivalintojaan. Taustana käytettiin teoreettista keskustelua kohdekielen ja äidinkielen hyödyistä kohdekielen oppimisen kannalta sekä aiempia tutkimustuloksia opettajien kielenkäytöstä. Tutkimuksen aineisto koostui kahdesta videokuvatusta kahdeksannen luokan englannin tunnista ja tunnit pitäneiden opettajien haastatteluista. Toisella ope…
SmartARP: merging IP and MAC addressing for low-cost gigabit Ethernet networks
1999
Abstract Address Resolution Protocol (ARP) is one of the key TCP/IP stack protocols, used on LANs to map 32 bit IP addresses into 48 bit hardware addresses. Regular ARP uses MAC layer broadcasts to perform the mapping. In this paper a new server-based ARP extension (smartARP) is proposed, which allows the extension of ARP functionality beyond a single MAC layer broadcast domain. Compared to regular IP router, smartARP together with simple broadcast-filtering switches presents a low-cost alternative for forwarding packets between MAC layer broadcast domains. SmartARP is transparent to existing IP hosts, operates independent of LAN speed, and scales for big networks.
ZERO: An Efficient Ethernet-Over-IP Tunneling Protocol
2013
An Ethernet over IPv4 tunneling protocol is proposed, which categorizes all Ethernet frames to be tunneled into NICE and UGLY frames. The UGLY frames are tunneled by traditional methods, such as UDP or GRE encapsulation, resulting in substantial overhead due to additional headers and fragmentation usually required to transport long Ethernet frames over IP network typically limited to MTU=1,500 bytes. Meanwhile the NICE Ethernet frames are tunneled without any overhead as plain IPv4 packets due to non-traditional reuse of “fragment offset” or “identification” field in the IP header. It is shown that for typical Internet traffic transported over Ethernet, the proposed ZERO tunneling protocol …
Transient dynamics of pulse-driven memristors in the presence of a stable fixed point
2019
Abstract Some memristors are quite interesting from the point of view of dynamical systems. When driven by narrow pulses of alternating polarities, their dynamics has a stable fixed point, which may be useful for future applications. We study the transient dynamics of two types of memristors characterized by a stable fixed point using a time-averaged evolution equation. Time-averaged trajectories of the Biolek window function memristor and resistor-threshold type memristor circuit (an effective memristor) are determined analytically, and the times of relaxation to the stable fixed point are found. Our analytical results are in perfect agreement with the results of numerical simulations.
Bifurcation analysis of a TaO memristor model
2019
This paper presents a study of bifurcation in the time-averaged dynamics of TaO memristors driven by narrow pulses of alternating polarities. The analysis, based on a physics-inspired model, focuses on the stable fixed points and on how these are affected by the pulse parameters. Our main finding is the identification of a driving regime when two stable fixed points exist simultaneously. To the best of our knowledge, such bistability is identified in a single memristor for the first time. This result can be readily tested experimentally, and is expected to be useful in future memristor circuit designs.
Objective function design for robust optimality of linear control under state-constraints and uncertainty
2009
We consider a model for the control of a linear network flow system with unknown but bounded demand and polytopic bounds on controlled flows. We are interested in the problem of finding a suitable objective function that makes robust optimal the policy represented by the so-called linear saturated feedback control. We regard the problem as a suitable differential game with switching cost and study it in the framework of the viscosity solutions theory for Bellman and Isaacs equations. © 2009 EDP Sciences, SMAI.
Simple Lossless Inductive Snubbers-Assisted Series Load Resonant Inverter Operating under ZCS-PDM Scheme for High-Frequency Induction Heating Fixed R…
2022
This paper presents a high-frequency pulse-density-modulated (PDM) soft-switching series load resonant inverter for use in induction heating (IH) fixed roller applications, which is used in copy and printing machines. The proposed simple high-frequency resonant inverter uses an asymmetrical pulse pattern PDM control scheme to achieve complete zero-current soft-switching commutations over a wide output range of input power regulation. Additionally, when the printer toner requires operation in very light load conditions, this causes difficulty in achieving zero-voltage or zero-current soft-switching operations in the IH high-frequency resonant inverters with pulse frequency modulation or puls…