1,721,512 research outputs found
2400-T66-32 Verucchi Marking Trees - National Forests and Grasslands
No full textVerucchi Marking Trees - National Forests and Grasslands.
Photographer: Unknownhttps://scholarworks.sfasu.edu/nfgt_general/2263/thumbnail.jp
2400-T66-24 Verucchi Core Sample Superior - National Forests and Grasslands
No full textVerucchi Core Sample Superior - National Forests and Grasslands.
Photographer: Unknownhttps://scholarworks.sfasu.edu/nfgt_general/2256/thumbnail.jp
Terapia delle epatiti virali croniche
No full textSi descrive il trattamento delle epatiti virali croniche focalizzando l'attenzione verso l'epatiti virali croniche HBV, HCV, HDV.
Vengono segnalati i vari farmaci utilizzabili riportando le caratteristiche, gli effetti collaterali e segnalando quando utilizzarl
Analisi esaustiva di DAG task: soluzioni per moderni sistemi real-time embedded
No full textI moderni sistemi cyber-fisici embedded integrano diverse funzionalità complesse che sono soggette a stringenti vincoli temporali.
Purtroppo, i tradizionali modelli di task sequenziali e le soluzioni per uniprocessori non possono essere applicati in questo contesto: diventa necessario un modello più espressivo.
In questo scenario, il Directed Acyclic Graph (DAG) è un modello adatto a esprimere la complessità e il parallelismo dei task di questo tipo di sistemi.
Negli ultimi anni sono stati proposti diversi metodi, con diverse configurazioni, per risolvere il problema della schedulabilità di applicazioni con DAG tasks. Tuttavia, rimangono ancora molti problemi aperti.
Oltre alla schedulabilità, aspetti come la freschezza dei dati o la reazione a un evento sono cruciali per le prestazioni di questo tipo di sistemi. Per esempio, una tipica applicazione nel campo automobilistico è costituita dal rilevamento dell'ambiente, dalla pianificazione e dall'attuazione basata sui dati elaborati. La latenza del controllo end-to-end è quindi decisiva, e può diventare molto complicata in scenari reali.
Questa tesi rappresenta uno sforzo in entrambe le direzioni: (i) la schedulabilità di DAG tasks su un multiprocessore, e (ii) la supervisione della latenza end-to-end per task a multi-frequenza.
Per il primo problema, viene presentata un'indagine sullo stato dell'arte del modello di task a grafico aciclico diretto, con particolare attenzione ai test più efficaci, facili da implementare e da adottare.
Per quanto riguarda il secondo, viene proposto un metodo per convertire un task-set di DAG a multi-frequenza con vincoli temporali in un DAG a singola frequenza che ottimizza la schedulabilità e la latenza end-to-end.Modern cyber-physical embedded systems integrate several complex functionalities that are subject to tight timing constraints.
Unfortunately, traditional sequential task models and uniprocessors solutions can not be applied in this context: a more expressive model becomes necessary.
In this scenario, the Directed Acyclic Graph (DAG) is a suitable model to express the complexity and the parallelism of the tasks of these kinds of systems.
In recent years, several methods with different settings have been proposed to solve the schedulability problem for applications featuring DAG tasks. However, there are still many open problems left.
Besides schedulability, aspects like the freshness of data or reaction to an event are crucial for the performance of those kind of systems.
For example, a typical application in the automotive field is composed of sensing the environment, planning, and actuate consequently to the elaborated data. Control end-to-end latency is then decisive, and it can get very complicated in real scenarios.
This thesis represents an effort in both directions: (i) the schedulability of a DAG task on a multiprocessor, and (ii) the supervision of end-to-end latency for multi-rate tasks.
For the former problem, a survey of the state-of-the-art of the Directed Acyclic Graph task model is presented, with a focus on scheduling tests that are more effective, easy to implement, and adopt.
Regarding the latter, a method is proposed to convert a multi-rate DAG task-set with timing constraints into a single-rate DAG that optimizes schedulability, age, and reaction latency
ION BEAM-STIMULATED AUGER-ELECTRON EMISSION FROM CR AND CR-SILICIDES
No full textThe emission of Auger electrons induced by energetic ions impact on Cr and Cr-silicides of different stoichiometry (Cr3Si and CrSi2) was investigated. Attention was focused on the origin, nature and characteristics of the metal peaks and on the role of asymmetric metal-silicon collision for the Cr and Si atom excitation. The ion excited, M23-related, low energy Cr spectrum essentially originates in the decay of slow sputtered Cr atoms. The Cr autoionization satellite almost completely vanishes, while interatomic transitions involving Cr and Ar atoms occur. Cr-Si collisions have been found to be efficient for the ionization of either Si and Cr atoms, indicating that excitation can also occur in the heavier partner
Electronic properties of tetrakis(pentafluorophenyl)porphyrin
No full textWe studied in detail the electronic properties of C44H10F20N4 (tetrakis(pentafluorophenyl)porphyrin, hereafter H2TPP(F)) via a combined study by photoelectron spectroscopy (PES) and density functional (DF) calculations, shedding new light on the role of the halide in this very interesting molecule for organic electronics. Valence and core levels have been investigated by means of PES on H2TPP(F) thin films deposited on the SiO2/Si(100) native oxide surface by supersonic molecular beam deposition (SuMBD). These experiments have been carefully interpreted on the basis of DF results pertaining to the isolated H2TPP(F). Non-relativistic calculations have been run to investigate valence states, whereas a two component relativistic approach within the zeroth-order regular approximation has been adopted to study core levels. The present results, in conjunction with those obtained previously on the H2TPP parent compound [M. Nardi, R. Verucchi, C. Corradi, M. Pola, M. Casarin, A. Vittadini and S. Iannotta, Phys. Chem. Chem. Phys., 2010, 12, 871], pave the way towards designing fully organic p–n junctions by using these macrocycles
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Triode electron bombardment evaporation source for ultrahigh vacuum thin film deposition
No full textA new electron bombardment evaporation source for ultrahigh vacuum (UHV) thin film deposition is presented. It is based on an original electrodes configuration (modeled on that of a vacuum triode) featuring, besides anode and filament, a biased grid acting as a power modulator. The presence of a polarized grid helps to minimize space charge problems, to improve electron focusing and to fine control the dissipation on the evaporating material, governing the sublimation rate. The electrodes geometry was optimized by studying electron trajectories and electrical field distribution in the electrodes zone with ray-tracing analysis. Mechanical solutions and electrodes geometry were designed to ensure low outgassing and UHV compatibility, as well as to facilitate maintenance and source cleaning. The evaporator is water cooled and a mechanically operated shutter is present. The working principles and the technical details are presented together with operating data and evaporation performances
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