389 research outputs found
GT2006-90590 PERFORMANCE OF GAS TURBINE POWER PLANTS CONTROLLED BY MULTIAGENT SCHEME
ABSTRACT In latter years the idea of artificial intelligence has been focused around the concept of a rational agent. An agent is a (software or hardware) entity that can receive signals from the environment and act upon that environment through output signals. In general an agent always tries to carry out an appropriate task. Seldom agents are considered as stand-alone systems. Their main strength can be found in the interaction with other agents in several different ways in a multiagent system. In the present work, multiagent system approach will be used to manage the control process of a single-shaft heavy-duty gas turbine in Multi Input Multi Output mode. The results will show that the multiagent approach to the control problem effectively counteracts the load reduction (including the load rejection condition) with limited overshoot in the controlled variables (as other control algorithms do) while showing good level adaptivity readiness, precision, robustness and stability
Radiation and Scattering of EM Waves in Large Plasmas Around Objects in Hypersonic Flight
Hypersonic flight regime is conventionally defined for Mach larger than 5; in
these conditions, the flying object becomes enveloped in a plasma. This plasma
is densest in thin surface layers, but in typical situations of interest it
impacts electromagnetic wave propagation in an electrically large volume. We
address this problem with a hybrid approach. We employ Equivalence Theorem to
separate the inhomogeneous plasma region from the surrounding free space via an
equivalent (Huygens) surface, and the Eikonal approximation to Maxwell
equations in the large inhomogeneous region for obtaining equivalent currents
on the separating surface. Then, we obtain the scattered field via (exact) free
space radiation of these surface equivalent currents. The method is extensively
tested against reference results and then applied to a real-life re-entry
vehicle with full 3D plasma computed via Computational Fluid Dynamic (CFD)
simulations. We address both scattering (RCS) from the entire vehicle and
radiation from the on-board antennas. From our results, significant radio link
path losses can be associated with plasma spatial variations (gradients) and
collisional losses, to an extent that matches well the usually perceived
blackout in crossing layers in cutoff. Furthermore, we find good agreement with
existing literature concerning significant alterations of the radar response
(RCS) due to the plasma envelope
On The Potential of Minimal Flavour Violation
Assuming the Minimal Flavour Violation hypothesis, we derive the general
scalar potential for fields whose background values are the Yukawa couplings.
We analyze the minimum of the potential and discuss the fine-tuning required to
dynamically generate the mass hierarchies and the mixings between different
quark generations. Two main cases are considered, corresponding to Yukawa
interactions being effective operators of dimension five or six (or,
equivalently, resulting from bi-fundamental and fundamental scalar fields,
respectively). At the renormalizable and classical level, no mixing is
naturally induced from dimension five Yukawa operators. On the contrary, from
dimension six Yukawa operators one mixing angle and a strong mass hierarchy
among the generations result.Comment: 33 pages, 6 figures; Note added in proof on the stability of the
minima of the scalar potential; results unchanged; references adde
CP Violation in Supersymmetry with Effective Minimal Flavour Violation
We analyze CP violation in supersymmetry with Effective Minimal Flavour
Violation, as recently proposed in arXiv:1011.0730. Unlike the case of standard
Minimal Flavour Violation, we show that all the phases allowed by the flavour
symmetry can be sizable without violating existing Electric Dipole Moment
constraints, thus solving the SUSY CP problem. The EDMs at one and two loops
are precisely analyzed as well as their correlations with the expected CP
asymmetries in B physics.Comment: 22 pages, 7 figures. v2: Discussion in section 2 extended,
conclusions unchanged. Matches published versio
Verocytotoxin-Producing Escherichia coli O26 in raw water buffalo (Bubalus bubalis) milk products in Italy
Escherichia coli 026 is known as a verocytotoxin-producing E. coli (VTEC) organism that causes severe foodborne diseases such as hemorrhagic colitis and hemolytic uremic syndrome. Although cattle are the most important reservoir of VTEC, only a few reports on the role of water buffalo (Bubalus bubalis) as a reservoir of VTEC and on the presence of these organisms in their milk are available. However, in Southern Italy, where water buffalo are intensively reared, an outbreak of hemolytic uremic syndrome due to E. coli 026 has recently been reported, in which the consumption of typical dairy products was considered to be a common risk factor. The aims of this work were to assess the prevalence of E. coli 026 in raw water buffalo milk, to characterize the virulence gene profiles of the isolates, and to evaluate their phenotypic antimicrobial resistance pattern. Of 160 analyzed samples, 1 (0.6%) tested positive for E. coli 026, and the isolate showed the stx1+ lstx2+leae-lhlyA+ genotypic profile. The strain showed resistance against glycopeptides, macrolides, and penicillins. The presence of VTEC organisms in raw water buffalo milk could be considered to be a potential threat to consumers; however, the strict adherence to the processes used in the preparation of the most common buffalo dairy products could strongly mitigate the foodborne risk. To our knowledge, this article reports the first isolation and characterization of E. coli 026 VTEC in raw water buffalo milk. Copyright ©, International Association for Food Protectio
Search for Gravitational Waves from Primordial Black Hole Binary Coalescences in the Galactic Halo
We use data from the second science run of the LIGO gravitational-wave
detectors to search for the gravitational waves from primordial black hole
(PBH) binary coalescence with component masses in the range 0.2--.
The analysis requires a signal to be found in the data from both LIGO
observatories, according to a set of coincidence criteria. No inspiral signals
were found. Assuming a spherical halo with core radius 5 kpc extending to 50
kpc containing non-spinning black holes with masses in the range 0.2--, we place an observational upper limit on the rate of PBH coalescence
of 63 per year per Milky Way halo (MWH) with 90% confidence.Comment: 7 pages, 4 figures, to be submitted to Phys. Rev.
Flavor Symmetric Sectors and Collider Physics
We discuss the phenomenology of effective field theories with new scalar or
vector representations of the Standard Model quark flavor symmetry group,
allowing for large flavor breaking involving the third generation. Such field
content can have a relatively low mass scale \lesssim TeV and O(1) couplings to
quarks, while being naturally consistent with both flavor violating and flavor
diagonal constraints. These theories therefore have the potential for early
discovery at LHC, and provide a flavor safe "tool box" for addressing anomalies
at colliders and low energy experiments. We catalogue the possible flavor
symmetric representations, and consider applications to the anomalous Tevatron
t-tbar forward backward asymmetry and B_s mixing measurements, individually or
concurrently. Collider signatures and constraints on flavor symmetric models
are also studied more generally. In our examination of the t-tbar forward
backward asymmetry we determine model independent acceptance corrections
appropriate for comparing against CDF data that can be applied to any model
seeking to explain the t-tbar forward backward asymmetry.Comment: 71 pages, 14 Figures, 12 Table
Dental Health and Mortality in People With End-Stage Kidney Disease Treated With Hemodialysis: A Multinational Cohort Study
Background Dental disease is more extensive in adults with chronic kidney disease, but whether dental health and behaviors are associated with survival in the setting of hemodialysis is unknown. Study Design Prospective multinational cohort. Setting & Participants 4,205 adults treated with long-term hemodialysis, 2010 to 2012 (Oral Diseases in Hemodialysis [ORAL-D] Study). Predictors Dental health as assessed by a standardized dental examination using World Health Organization guidelines and personal oral care, including edentulousness; decayed, missing, and filled teeth index; teeth brushing and flossing; and dental health consultation. Outcomes All-cause and cardiovascular mortality at 12 months after dental assessment. Measurements Multivariable-adjusted Cox proportional hazards regression models fitted with shared frailty to account for clustering of mortality risk within countries. Results During a mean follow-up of 22.1 months, 942 deaths occurred, including 477 cardiovascular deaths. Edentulousness (adjusted HR, 1.29; 95% CI, 1.10-1.51) and decayed, missing, or filled teeth score ≥ 14 (adjusted HR, 1.70; 95% CI, 1.33-2.17) were associated with early all-cause mortality, while dental flossing, using mouthwash, brushing teeth daily, spending at least 2 minutes on oral hygiene daily, changing a toothbrush at least every 3 months, and visiting a dentist within the past 6 months (adjusted HRs of 0.52 [95% CI, 0.32-0.85], 0.79 [95% CI, 0.64-0.97], 0.76 [95% CI, 0.58-0.99], 0.84 [95% CI, 0.71-0.99], 0.79 [95% CI, 0.65-0.95], and 0.79 [95% CI, 0.65-0.96], respectively) were associated with better survival. Results for cardiovascular mortality were similar. Limitations Convenience sample of clinics. Conclusions In adults treated with hemodialysis, poorer dental health was associated with early death, whereas preventive dental health practices were associated with longer survival
Synthesis of Recommendations From 25 Countries and 31 Oncology Societies: How to Navigate Through Covid-19 Labyrinth
Introduction: Pandemic COVID-19 is an unexpected challenge for the oncological community, indicating potential detrimental effects on cancer patients. Our aim was to summarize the converging key points providing a general guidance in order to support decision making, pertaining to the oncologic care in the middle of a global outbreak.
Methods: We did an international online search in twenty five countries that have managed a surge in cancer patient numbers. We collected the recommendations from thirty one medical oncology societies.
Results: By synthesizing guidelines for a) oncology service delivery adjustments, b) general and specific treatment adaptations, and c) discrepancies from guidelines comparison, we present a clinical synopsis with the forty more crucial statements. A Covid-19 risk stratification base was also created in order to obtain a quick, objective patient assessment and a risk-benefit evaluation on a case-by-case basis.
Conclusions: In an attempt to face these complex needs and due to limited understanding of COVID-19, a variability of recommendations based on general epidemiological and infectious disease principles rather than definite cancer-related evidence has evolved. Additionally, the absence of an effective treatment or vaccine requires the development of cancer management guidance, capitalizing on comprehensive COVID-19 oncology experience globally
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