5,931 research outputs found
Quantum thermodynamic Carnot and Otto-like cycles for a two-level system
From the thermodynamic equilibrium properties of a two-level system with
variable energy-level gap , and a careful distinction between the Gibbs
relation and the energy balance equation , we infer some important aspects of the
second law of thermodynamics and, contrary to a recent suggestion based on the
analysis of an Otto-like thermodynamic cycle between two values of of
a spin-1/2 system, we show that a quantum thermodynamic Carnot cycle, with the
celebrated optimal efficiency , is possible in
principle with no need of an infinite number of infinitesimal processes,
provided we cycle smoothly over at least three (in general four) values of
, and we change not only along the isoentropics, but also
along the isotherms, e.g., by use of the recently suggested maser-laser tandem
technique. We derive general bounds to the net-work to high-temperature-heat
ratio for a Carnot cycle and for the 'inscribed' Otto-like cycle, and represent
these cycles on useful thermodynamic diagrams.Comment: RevTex4, 4 pages, 1 figur
A Fast General-Purpose Clustering Algorithm Based on FPGAs for High-Throughput Data Processing
We present a fast general-purpose algorithm for high-throughput clustering of
data "with a two dimensional organization". The algorithm is designed to be
implemented with FPGAs or custom electronics. The key feature is a processing
time that scales linearly with the amount of data to be processed. This means
that clustering can be performed in pipeline with the readout, without
suffering from combinatorial delays due to looping multiple times through all
the data. This feature makes this algorithm especially well suited for problems
where the data has high density, e.g. in the case of tracking devices working
under high-luminosity condition such as those of LHC or Super-LHC. The
algorithm is organized in two steps: the first step (core) clusters the data;
the second step analyzes each cluster of data to extract the desired
information. The current algorithm is developed as a clustering device for
modern high-energy physics pixel detectors. However, the algorithm has much
broader field of applications. In fact, its core does not specifically rely on
the kind of data or detector it is working for, while the second step can and
should be tailored for a given application. Applications can thus be foreseen
to other detectors and other scientific fields ranging from HEP calorimeters to
medical imaging. An additional advantage of this two steps approach is that the
typical clustering related calculations (second step) are separated from the
combinatorial complications of clustering. This separation simplifies the
design of the second step and it enables it to perform sophisticated
calculations achieving online-quality in online applications. The algorithm is
general purpose in the sense that only minimal assumptions on the kind of
clustering to be performed are made.Comment: 11th Frontier Detectors For Frontier Physics conference (2009
Combustion and operating characteristics of spark-ignition engines
The spark-ignition engine turbulent flame propagation process was investigated. Then, using a spark-ignition engine cycle simulation and combustion model, the impact of turbocharging and heat transfer variations or engine power, efficiency, and NO sub x emissions was examined
Effects of climate change on the Nossana karst spring (northern Italy): future discharge projections and water distribution system sustainability
Nossana represents an important pre-Alpine karst spring located in Lombardy Region (Northern Italy). It is used for drinking supply and it sustains a water distribution system serving 300,000 people, including the city of Bergamo. The objective of this study was to project Nossana discharges, to evaluate potential supply limits for four future periods (2021-2040, 2041-2060, 2061-2080, 2081-2100). The study was carried out following a four-step approach. First, the EURO-CORDEX bias-corrected Regional Climate Models (RCMs) available for all the emission scenarios (RCP2.6, RCP4.5, RCP8.5) were evaluated in terms of precipitation and temperature monthly climatology. Second, they were statistically downscaled by means of change factors and a stochastic weather generator. Third, a rainfall-runoff model ensemble accounting also for snow dynamics (GR4J with CemaNeige module) was calibrated and validated on historical time series (1998-2017). Finally, the future downscaled time series were used as input in the calibrated model and the projected discharges evaluated in terms of low flow. In detail, two warning discharge thresholds - one for high water demand periods and one for ordinary water demand periods - were recognized with the service company managing the spring (Uniacque S.p.A.). Then, the number of (consecutive) days below them were calculated for each future period and compared to the historical time series. For each emission scenario, the calibrated model ensemble counted three RCMs and ten rainfall-runoff parameterizations. Projected ensemble mean discharges are lower than observations for all future periods and RCPs (from -3% for 2021-2040 and RCP4.5 to -23% for 2081-2100 and RCP8.5), although they do not show a clear trend between the four time periods. Days characterized by discharges lower than the warning thresholds are projected to decrease except for the RCP8.5 emission scenarios and the period 2081-2100 (14% increase for the ordinary-demand threshold, 10% increase for the high-demand threshold). Conversely, consecutive days are expected to increase between 2061 and 2100 for all emission scenarios and the two thresholds (by 0% and 26% for RCP 2.6, by 8% and 15% for RCP 4.5, by 28% and 48% for RCP 8.5). These results reflect the projected precipitation trend, characterized by longer, drier summer periods and wetter autumns in comparison to today\u2019s climate. Also, they indicate the need to develop a plan for the research and use of alternative drinking water resources for the long-term period. Therefore, the proposed methodology demonstrated to deliver useful information for water management planning. Future studies are intended to focus on chemistry and isotopic composition of water
Is Cross-Reactive Immunity Triggering COVID-19 Immunopathogenesis?
The serological responses to both SARS-CoV-1 and SARS-CoV-2 virus have some unique characteristics that suggest cross-reactive priming by other human coronaviruses (hCoVs). The early kinetics and magnitude of these responses are, in some cases, associated with worse clinical outcomes in SARS and COVID-19. Cross-reactive hCoV antibody responses have been detected in both SARS and COVID-19 patients. There is also evidence that pre-existing T cell immunity to common cold coronaviruses can prime the response to SARS-CoV-2. Studies in non-human primates show that SARS-CoV-1 S-protein vaccine-induced antibodies are associated with acute lung injury in macaques challenged with SARS-CoV-1. Here we discuss the potential of cross-reactive immunity to drive the immunopathogenesis of COVID-19 and its implications for current efforts to develop immune-based therapies and vaccines
A Note on the KKT Points for the Motzkin-Straus Program
In a seminal 1965 paper, Motzkin and Straus established an elegant connection between the clique number of a graph and the global maxima of a quadratic program defined on the standard simplex. Since then, the result has been the subject of intensive research and has served as the motivation for a number of heuristics and bounds for the maximum clique problem. Most of the studies available in the literature, however, focus typically on the local/global solutions of the program, and little or no attention has been devoted so far to the study of its Karush-Kuhn-Tucker (KKT) points. In contrast, in this paper we study the properties of (a parameterized version of) the Motzkin-Straus program and show that its KKT points can provide interesting structural information and are in fact associated with certain regular sub-structures of the underlying graph
Detecting Addiction, Anxiety, and Depression by Users Psychometric Profiles
Detecting and characterizing people with mental disorders is an important task that could help the work of different healthcare professionals. Sometimes, a diagnosis for specific mental disorders requires a long time, possibly causing problems because being diagnosed can give access to support groups, treatment programs, and medications that might help the patients. In this paper, we study the problem of exploiting supervised learning approaches, based on users' psychometric profiles extracted from Reddit posts, to detect users dealing with Addiction, Anxiety, and Depression disorders. The empirical evaluation shows an excellent predictive power of the psychometric profile and that features capturing the post's content are more effective for the classification task than features describing the user writing style. We achieve an accuracy of 96% using the entire psychometric profile and an accuracy of 95% when we exclude from the user profile linguistic features
Strong solutions of the thin film equation in spherical geometry
We study existence and long-time behaviour of strong solutions for the thin
film equation using a priori estimates in a weighted Sobolev space. This
equation can be classified as a doubly degenerate fourth-order parabolic and it
models coating flow on the outer surface of a sphere. It is shown that the
strong solution asymptotically decays to the flat profile
Analisi basata sugli sforzi locali della resistenza a fatica di giunzioni incollate di materiali compositi
Il lavoro prende spunto dai risultati di unâanalisi sperimentale del comportamento a fatica di giunzioni incollate di materiali compositi laminati di elevato spessore formati da strati di unidirezionale e di tessuto di fibra di carbonio. I giunti sono stati realizzati in modo tale da saggiare lâinfluenza della lunghezza di sovrapposizione (da 25,4 mm a 110,8 mm), della forma del giunto (con e senza rastremazione), e della composizione degli aderendi (sostituzione di uno degli aderendi in composito con uno in acciaio). Mediante analisi 2D elastiche con il metodo degli elementi finiti sono state ricavate le distribuzioni degli sforzi allâinterno dello strato di adesivo, al fine di individuare un parametro utile alla descrizione del comportamento a fatica in termini di sforzi locali - numero di cicli a rottura. Il ruolo della fase di propagazione viene discusso alla luce di osservazioni dellâavanzamento della frattura, condotta su alcuni dei giunti testati
Impianti di ionizzazione Cu-Ag per la di disinfezione delle acque e rischi di corrosione per spostamento
The copper and silver ionization system is one of the water sanitation treatments. Effective ionization occurs if the
content of copper ions in solution is 0.2-0.4 mg/L and that of silver ions is 0.02-0.04 mg/L. An excess of copper
and silver ions can react with other metal surfaces, triggering a deposition reaction, allowing the formation of
deposits of more noble metals, and then promoting a localized corrosion phenomenon due to galvanic coupling.
In the present paper, two case histories will be presented: one related to a legionella sanitizing plant system of a
hospital; the second related to a system of water purification of a vessel on a boat. In both cases, working
conditions are illustrated, corrosion morphology is described, focusing on the presence of copper and silver
deposits, and the cause of corrosion is presented, estimating a reliable corrosion rate
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