In this manuscript, a novel sag and peak detector by means of a delta square operation for a single-phase is suggested. The established sag detector is from a single phase digital phase-locked loop ...(DPLL) that is founded on a d-q transformation employing an all-pass filter (APF). The d-q transformation is typically employed in the three-phase coordinate system. The APF produces a virtual phase with a 90° phase delay, but the virtual phase can not reproduce an abrupt variation of the grid voltage, at the moment in which the voltage sag transpires. As a consequence, the peak value is severely garbled, and settles down gradually. A modified APF produces the virtual q-axis voltage factor from the difference between the current and the former value of the d-axis voltage component in the stationary reference frame. Nevertheless, the amended APF cannot sense the voltage sag and peak value when the sag transpires around the zero crossing points such as 0° and 180° since the difference voltage is not adequate to sense the voltage sag. The suggested algorithm is proficient to sense the sag voltage through all regions as well as the zero crossing voltage. Furthermore, the precise voltage drop can be obtained by computing the q-axis component, which is relational to the d-axis component. To authenticate the legitimacy of the suggested scheme, the orthodox and suggested approaches are contrasted by means of the simulations and investigational results.
Ob padcu utopije De Decker, Pascal; Newton, Caroline
Urbani izziv,
01/2009, Letnik:
20, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Po koncu 2. svetovne vojne so se začele graditi velike stanovanjske soseske. Pogosto so jih sestavljale stolpnice. Številne le 50 let pozneje podirajo oziroma jih temeljito prenavljajo. Modernistične ...ideje, ki so jih navdihnili predstavniki kongresa CIAM (Congrès International d’Architecture Moderne) in Le Corbusier, so izgubile nekdanjo mikavnost. V tem prispevku si bomo ogledali razvoj dogodkov, predvsem pa se bomo posvetili napačni razlagi (simbolnega) pomena bivališča, kakor so ga razumeli predstavniki modernističnega gibanja. Prav to napačno razumevanje je nazadnje pripeljalo do hitrega podiranja teh sosesk.
U ovom radu je predložen novi detektor propada i poskoka napona korištenjem delta kvadratične operacije za jednu fazu. Predloženi detektor propada napona je u digitalnoj fazno-zatvorenoj petlji ...(DPLL) zasnovanoj na d-q transformaciji koja koristi svepropusni filtar (APF). D-q transformacija se tipično koristi u trofaznim koordinatnim sustavima. APF generira virtualnu fazu s 90 deg faznog kašnjenja, ali virtualna faza ne može reproducirati skokovitu promjenu napona mreže u trenutku u kojem se događa propad napona. Kao posljedica, detektirana vršna vrijednost se značajno izmijeni i smiruje se postepeno. Modificirani APF generira faktor napona virtualne q osi iz razlike između struje i prošle vrijednosti komponente napona na d osi u stacionarnom koordinatnom sustavu. Međutim, izmijenjeni APF ne može detektirati propad i poskok napona kada se propad događa u okolini točaka presijecanja nule, kao što je 0 deg i 180 deg s obzirom da diferencijski napon nije prikladan za detekciju propada napona. Predloženi algoritam je prilagođen detekciji propada napona u cijelom radnom području, uključujući i napon prelaska nule. Nadalje, precizni propad napona može se dobiti izračunom komponente napona na q osi, koja je u odnosu s obzirom na komponentu d osi. Za validaciju predloženih metoda provedena je njihova usporedba s konvencionalnim metodama u simulacijskom i eksperimentalnom okruženju.
U ovom radu analizira se razdioba naponskih propada na distribucijskom izvodu u istočnom dijelu Hrvatske. Prikazan je rezultat nadzora (monitoringa) pokazatelja kvalitete električne energije na ...transformatorskoj stanici 110/35 kV. Mjerenje je izvedeno pomoću mrežnih analizatora kvalitete električne energije i to na sekundarnim stranama dvaju transformatora. Rezultati su objedinjeni i statistički obrađeni: naponski događaji klasificirani su u skladu s normama EN 50160 i IEEE 1159:1995, a izračunati su i pokazatelji učestalosti promjena efektivne vrijednosti napona. Istraživanje je izvedeno u sklopu projekta Leonardo Power Quality Initiative, u kojem je Elektrotehnički fakultet Osijek bio pridruženi partner.
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The fracture of polycrystalline graphene is explored by performing molecular dynamics simulations with realistic finite-grain-size models, emphasizing the role of grain boundary ends and junctions. ...The simulations reveal a ∼50% or more strength reduction due to the presence of the network of boundaries between polygonal grains, with cracks preferentially starting at the junctions. With a larger grain size, a surprising systematic decrease of tensile strength and failure strain is observed, while the elastic modulus rises. The observed crack localization and strength behavior are well-explained by a dislocation-pileup model, reminiscent of the Hall–Petch effect but coming from different underlying physics.
An ongoing challenge in neuromorphic computing is to devise general and computationally efficient models of inference and learning which are compatible with the spatial and temporal constraints of ...the brain. One increasingly popular and successful approach is to take inspiration from inference and learning algorithms used in deep neural networks. However, the workhorse of deep learning, the gradient descent Gradient Back Propagation (BP) rule, often relies on the immediate availability of network-wide information stored with high-precision memory during learning, and precise operations that are difficult to realize in neuromorphic hardware. Remarkably, recent work showed that exact backpropagated gradients are not essential for learning deep representations. Building on these results, we demonstrate an event-driven random BP (eRBP) rule that uses an error-modulated synaptic plasticity for learning deep representations. Using a two-compartment Leaky Integrate & Fire (I&F) neuron, the rule requires only one addition and two comparisons for each synaptic weight, making it very suitable for implementation in digital or mixed-signal neuromorphic hardware. Our results show that using eRBP, deep representations are rapidly learned, achieving classification accuracies on permutation invariant datasets comparable to those obtained in artificial neural network simulations on GPUs, while being robust to neural and synaptic state quantizations during learning.
•Ti0.47V0.46Mn and Ti0.50V0.51Mn alloys were produced by arc melting.•Compositional differences led to different unit cell volumes for the C14 Laves phase.•Change in composition caused a significant ...change in plateau pressure and hysteresis.
Two Ti–V–Mn BCC-Laves phase alloys with the nominal composition Ti0.5V0.5±xMn (x=−0.04 and 0.01), were synthesised by arc melting. This compositional difference resulted in different compositions and unit cell volumes for the C14 Laves phase. Ti0.47V0.46Mn and Ti0.50V0.51Mn demonstrated reversible hydrogen sorption capacities of 1.53 and 1.56±0.05wt.% (at 120bar H2 at 303K) respectively, however, the change in composition results in a small change in the enthalpy of hydride decomposition, and a significant change in plateau pressure and hysteresis. This may allow for the plateau pressure to be tuned to meet the requirements of different solid-state hydrogen storage applications.
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