Thermal effects on chaotic directed transport

We study a chaotic ratchet system under the influence of a thermal environment. By direct integration of the Lindblad equation we are able to analyze its behavior for a wide range of couplings with the environment, and for different finite temperatures. We observe that the enhancement of the classical and quantum currents due to temperature depend strongly on the specific properties of the system. This makes difficult to extract universal behaviors. We have also found that there is an analogy between the effects of the classical thermal noise and those of the finite $\hbar$ size. These results open many possibilities for their testing and implementation in kicked BECs and cold atoms experiments.Comment: 5 pages, 4 figure

Minimization of the primary energy consumption of residential users connected by means of an energy grid

open4noIn this paper, a physics-based model is developed to simulate the interaction between residential users and energy systems. The simulation model is coupled with a dynamic programming algorithm which identifies the optimal operation strategy that allows the minimization of the primary energy consumption of three residential users, arranged with different energy system configurations. The reference scenario, which considers that the users employ a domestic boiler for meeting thermal energy demand, while electric energy is taken from the national electric grid, is compared to the CHP scenario, this latter being differentiated by considering shared thermal and electric energy storages and also shared PM. The most suitable energy system configuration is identified by jointly evaluating primary energy consumption, prime mover working hours and thermal and electric energy share of the prime mover itself.openCattozzo M., Manservigi L., Spina P. R., Venturini M.,Cattozzo, M.; Manservigi, L.; Spina, P. R.; Venturini, M

ARX LINEAR MODEL SET-UP FOR FAULT DIAGNOSIS OF GAS TURBINE SENSORS

ABSTRACT The diagnosis of gas turbine sensor faults requires models of the system to calculate estimates of the measured output system variables. The model set-up phase is of great importance since the reliability of the diagnostic tool depends on the model accuracy. In the paper two different methodologies of I/O linear model set-up are analyzed and compared to find the more simple and general one. The first methodology consists in obtaining the I/0 linear models by directly linearizing the physical laws (system modeling). The second one uses statistical methods (system identification) to calculate model parameters from time series data measured on the machine. The models used are of the ARX (Auto Regressive with eXtemal input) type. The number of models and the measured variables correlated by each of them have been determined in order to obtain unambiguous fault signatures for each sensor. The system identification method proves to be more suitable to the system modeling because of its greater simplicity in the fault diagnosis application. NOMENCLATUR

A PROGRAM FOR THE EVALUATION OF POLLUTANT EMISSIONS IN COMBINED CYCLE POWER PLANTS WITH SUPPLEMENTARY FIRING

ABSTRACT In this paper, a one-dimensional program for evaluating pollutant emissions in combined cycle power plant with supplementary firing is presented. The program uses Chemical Reactors analysis based on a Perfectly Stirred Reactor approach in conjunction with an emission model that simulates a detailed chemical kinetic scheme for combustion process modelling. The program allows the evaluation of the main pollutant emissions deriving from natural gas and oil combustion. In order to simulate combustion systems that can be found in a fired combined cycle power plant, the developed program presents some extended features with respect to programs developed for gas turbine combustors only. In order to reproduce a wide typology of combustors, the combustor geometry is represented using two characteristic dimensions (hydraulic diameter and length) and the considered domain is divided into reactors in series (along the axial direction) and in parallel (along the radial direction). The temperature in each reactor is determined taking into account both the convective and the radiative heat transfer between hot gases and walls. The program has been applied to two cases. In the first the numerical predictions have been compared with available experimental data relative to two gas turbine combustors. In the second case the program has been instead applied to a cylindrical test burner designed in accordance with EN 267 European Standard. The obtained results are acceptable from an engineering point of view and have been considered sufficiently accurate for this preliminary set-up phase of the model

New insights into volcanic processes at Stromboli from Cerberus, a remote-controlled open-path FTIR scanner system

The ordinary, low intensity, activity of Stromboli volcano is sporadically interrupted by more energetic events termed, depending on their intensity, “major explosions” and “paroxysms”. These short-lived energetic episodes represent a potential risk to visitors to the highly accessible summit of Stromboli. Observations made at Stromboli over the last decade have shown that the composition of gas emitted from the summit craters may change prior to such explosions, allowing the possibility that such changes may be used to forecast these potentially dangerous events. In 2008 we installed a novel, remote-controlled, open-path FTIR scanning system called Cerberus at the summit of Stromboli, with the objective of measuring gas compositions from individual vents within the summit crater terrace of the volcano with high temporal resolution and for extended periods. In this work we report the first results from the Cerberus system, collected in August-September 2009, November 2009 and May-June 2010. We find significant, fairly consistent, intra-crater variability for CO2/SO2 and H2O/CO2 ratios, and relatively homogeneous SO2/HCl ratios. In general, the southwest crater is richest in CO2, and the northeast crater poorest, while the central crater is richest in H2O. It thus appears that during the measurement period the southwest crater had a somewhat more direct connection to a primary, deep degassing system; whilst the central and northeast craters reflect a slightly more secondary degassing nature, with a supplementary, shallow H2O source for the central crater, probably related to puffing activity. Such water-rich emissions from the central crater can account for the lower crystal content of its eruption products, and emphasise the role of continual magma supply to the shallowest levels of Stromboli's plumbing system. Our observations of heterogeneous crater gas emissions and high H2O/CO2 ratios do not agree with models of CO2-flushing, and we show that simple depressurisation during magma ascent to the surface is a more likely model for H2O loss at Stromboli. We highlight that alternative explanations other than CO2 flushing are required to explain distributions of H2O and CO2 amounts dissolved in melt inclusions. We detected fairly systematic increases in CO2/SO2 ratio some weeks prior to major explosions, and some evidence of a decrease in this ratio in the days immediately preceding the explosions, with periods of low, stable CO2/SO2 ratios between explosions otherwise. Our measurements, therefore, confirm the medium term (~ weeks) precursory increases previously observed with MultiGas instruments, and, in addition, reveal new, short-term precursory decreases in CO2/SO2 ratios. immediately prior to the major explosions. Such patterns, if shown to be systematic, may be of great utility for hazard management at Stromboli's summit. Our results suggest that intra-crater CO2/SO2 variability may produce short-term peaks and troughs in CO2/SO2 time series measured with in-situ MultiGas instruments, due simply to variations in wind direction

Association between Boarding of Frail Individuals in the Emergency Department and Mortality: A Systematic Review

Background: Older patients who attend emergency departments are frailer than younger patients and are at a high risk of adverse outcomes; (2) Methods: To conduct this systematic review, we adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Guidelines. We systematically searched literature from PubMed, Embase, OVID Medline®, Scopus, CINAHL via EBSCOHost, and the Cochrane Library up to May 2023, while for grey literature we used Google Scholar. No time restrictions were applied, and only articles published in English were included. Two independent reviewers assessed the eligibility of the studies and extracted relevant data from the articles that met our predefined inclusion criteria. The Critical Appraisal Skills Program (CASP) was used to assess the quality of the studies; (3) Results: Evidence indicates that prolonged boarding of frail individuals in crowded emergency departments (Eds) is associated with adverse outcomes, exacerbation of pre-existing conditions, and increased mortality risk; (4) Conclusions: Our results suggest that frail individuals are at risk of longer ED stays and higher mortality rates. However, the association between the mortality of frail patients and the amount of time a patient spends in exposure to the ED environment has not been fully explored. Further studies are needed to confirm this hypothesis

A strategy for the robust forecasting of gas turbine health subjected to fouling

Fouling represents a major problem for Gas Turbines (GTs) in both heavy-duty and aeropropulsion applications. Solid particles entering the engine can stick to the internal surfaces and form deposits. Components' lifetime and performance can dramatically vary as a consequence of this phenomenon. These effects impact the whole engine in terms of residual life, operating stability, and maintenance costs. In the High-Pressure Turbine (HPT), in particular, the high temperatures soft the particles and promote their adhesion, especially in the short term. Unfortunately, predicting the GT response to this detrimental issue is still an open problem for scientists. Furthermore, the stochastic variations of the components operating conditions increase the uncertainty of the forecasting results. In this work, a strategy to predict the effects of turbine fouling on the whole engine is proposed. A stationary Gas Path Analysis (GPA) has been performed for this scope to predict the GT health parameters. Their alteration as a consequence of fouling has been evaluated by scaling the turbine map. The scaling factor has been found by performing Computational Fluid Dynamic (CFD) simulations of a HPT nozzle with particle injection. Being its operating conditions strongly uncertain, a stochastic analysis has been conducted. The uncertainty sources considered are the circumferential hot core location and the turbulence level at the inlet. The study enables to build of confidence intervals on the GT health parameters predictions and represents a step forward towards a robust forecasting tool

Off-line washing effectiveness on a multistage axial compressor

The interaction between gas turbines and airborne particles determines detrimental effects on the performance, efficiency, and reliability of the power unit. When it is possible, the interaction is reduced by the use of inlet separators and filtration systems. In an aero engine, these barriers are difficult to implement, and only bigger particles (usually greater than 10 µm) are separated from the airflow. Small units, especially those equips helicopters, are usually affected by fouling issues, especially when the aircraft is employed in harsh environments such as firefighting and rescue activities. To recover this contamination, the unit is washed after the mission by ground operations to restore the unit performance by removing the deposits. This operation occurs during a sub-idle unit operation, and the washing process has to be effective when the engine operates in this off-design condition. In this paper, the evaluation of the washing performance during a sub-idle unit operation is carried out. The compressor unit is a multistage axial compressor that equips the Allison 250-C18 engine. The washing operation was performed by water, and a sensitivity analysis is carried out to discover the capability of water droplets to remove the contaminants. The experimental analysis involves the contamination of the unit by micro-sized soot particles and a washing operation by micro-sized water droplets. These experimental results are compared to numerical simulations to discover the effects of the washing operation on a small power unit during sub-idle operating conditions. The off-design regime imposes a specific evaluation of the proper setup of the washing strategy: flow separations involve wider regions in the compressor unit, and the removal capability is strongly related to the droplet path through the stages. The results show how in the off-design washing operation, the droplet diameter has greater importance than the water flow rate for reducing the deposits over the compressor stages. © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/

Effects of ecotrofin™ on milk yield, milk quality and serum biochemistry in lactating goats

A nutritional supplement (Ecotrofin™, by Vetoquinol Italia S.r.l) recommended in ruminants feeding to strengthen the physiological condition and improve digestive performance was tested in 20 pluriparae grazing goats divided in two groups (control and treated) to assess its possible effects on milk yield and quality and to assess eventual adverse effects. Animals from both groups also received 400 g/day of corn meal, and the treated group was supplemented with 20 g/head/day of the nutritional supplement. At the doses suggested by the manufacturer, despite a transient increase after 30 days of supplementation, Ecotrofin™ did not show significant effects on milk yield and, although some changes were found in the fatty acids profile, no significant improvement of MUFA and PUFA, as well as of omega-6:omega-3 ratio and CLA content were seen. Therefore, in our experimental conditions the supplementation of diet with Ecotrofin™ did not appear useful to improve goat's performance. A significant effect on kidney health markers (27 vs. 22.5 for urea and 0.83 vs. 0.76 for creatinine, p < 0.05) suggested a beneficial effect on renal function but, since levels fell in the normal ranges in both groups, such hypothesis would need further studies to be addressed