1,720,971 research outputs found
Implementation of synchronous frame harmonic control for high-performance AC power supplies
No full textDigital Control of Uninterruptible Power Supplies Based on Predictive Voltage and Current Regulators
No full textThe features of a digital control technique for uninterruptible power supplies (UPS’s) are described. The control is based on voltage and current predictive regulators, aiming to achieve a dead-beat type of response for the closed loop system. This way, the technique is able to achieve a good quality of dynamic performance, guaranteeing low distorted output voltage waveforms even in the presence of non-linear and highly distorting loads. The knowledge of the output filter parameters with a reasonable level of accuracy is the only data required to properly tune the controller. Besides, the only sensed quantities are the output voltage and the inverter output current. The controller also maintains the conventional multi-loop structure which, allowing the implementation of overcurrent protection for the power converter, is very often encountered in commercial UPS systems. The validity of the proposed strategy is demonstrated by means of simulation and experimental results referring to a single-phase UPS laboratory prototype (1 kVA). The digital controller is implemented by means of the connection of a ADSP21062 floating point DSP and of a ADMC401 motion
control DSP, both by Analog Devices
Uninterruptible power supply multi-loop control employing digital predictive voltage and current regulators
No full textOsteoporosi e Attività motoria
No full textThese are the results of a study regarding 30 women affected by osteoporosis with an age between 60 and 85 years. These patients attended a physical re-education course that lasted three month. Thanks to the collaboration of an ISEF coacher these patients improved meaningfully both from a densitometric and from a physical and phycological point of view, and it was possible to obtain economic saving, useful both for sanitary stucture and for single subject. Therefore the physical re-education can be consider an effective means of prevention
L'omologia e le sue applicazioni alla rappresentazione progettuale e tecnica dell'architettura
No full textIl procedimento di trasformazione di una prospettiva in un’assonometria fornisce una soluzione al problema del rilevamento di forma e dimensioni di un edificio da una fotografia, che ha il pregio di una grande visività e di fornire la restituzione della composizione volumetrica dell’edificio fotografato, molto utile per una valutazione d’insieme dei valori di massa di quest’ultimo.
Si esaminano i principali casi che più usualmente si verificano in pratica: il fotogramma è stato scattato da noi e sono noti perciò il punto principale e la distanza principale; caso in cui non sono noti né il punto principale né la distanza principale; esempio schematico di rilievo da fotografia di un edificio a croce latina; si risolve il caso in cui l’edificio non sia parallelepipedo rettangolo (ossia quando il diedro delle facciate dell’edificio non sia retto); l’immagine fotografica di un arco a tutto sesto determina il punto principale e la distanza principale ossia la posizione della macchina fotografica; si risolve il problema del rilievo di edificio con fuorisquadri; come rilevare angoli in verticale; raffronto del procedimento adottato con quello più tradizionale dell’omologia di ribaltamento nel modo indiretto e considerazioni sugli inconvenienti di quest’ultimo.
La fotografia è supposta dapprima ad asse focale orizzontale (prospettiva a quadro verticale); si considera un fronte edilizio molto movimentato e ricco di fuorisquadri; si suppongono noti quello che si dice “l’orientamento interno” della fotografia e “la prima orientazione”, ossia (in linguaggio prospettico: il punto principale, la distanza principale e l’orizzonte); per la restituzione del fronte fotografato, ossia per il suo rilievo, si può procedere molto speditamente ricorrendo all’omologia di ribaltamento fra l’immagine prospettica (fotografia) della pianta del fronte edilizio e il suo ribaltamento; si mostra come si risolva facilmente col procedimento omologico il problema dei punti di fuga inaccessibili; le stesse considerazioni fatte per una spezzata poligonale vengono estese al caso di linee piane qualsiasi, cioè al caso di fronti edilizi curvilinei.The process of transformation of a perspective in an axonometric provides a solution to the problem of the detection of the shape and size of a building from a photograph, which has the advantage of a large visuality and provide the return of the volumetric composition of the building photographed, very useful for an overall assessment of the values of the mass of the latter. examines the major cases which usually occur in practice: the frame has been taken by us and are known so the main point and principal distanc
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
