Fitting quantum noise models to tomography data

The presence of noise is currently one of the main obstacles to achieving large-scale quantum computation. Strategies to characterise and understand noise processes in quantum hardware are a critical part of mitigating it, especially as the overhead of full error correction and fault-tolerance is beyond the reach of current hardware. Non-Markovian effects are a particularly unfavourable type of noise, being both harder to analyse using standard techniques and more difficult to control using error correction. In this work we develop a set of efficient algorithms, based on the rigorous mathematical theory of Markovian master equations, to analyse and evaluate unknown noise processes. In the case of dynamics consistent with Markovian evolution, our algorithm outputs the best-fit Lindbladian, i.e., the generator of a memoryless quantum channel which best approximates the tomographic data to within the given precision. In the case of non-Markovian dynamics, our algorithm returns a quantitative and operationally meaningful measure of non-Markovianity in terms of isotropic noise addition. We provide a Python implementation of all our algorithms, and benchmark these on a range of 1- and 2-qubit examples of synthesised noisy tomography data, generated using the Cirq platform. The numerical results show that our algorithms succeed both in extracting a full description of the best-fit Lindbladian to the measured dynamics, and in computing accurate values of non-Markovianity that match analytical calculations

Development of a CFD methodology for fuel-air mixing and combustion modeling of GDI Engines

Simulation of GDI engines represents a very challenging task for CFD modeling. In particular, many sub-models are involved since the evolution of the fuel spray and liquid film formation should be modeled. Furthermore, it is necessary to account for both the influence of mixture and flow conditions close to the spark plug to correctly predict the flame propagation process. In this work, the authors developed a CFD methodology to study the air-fuel mixing and combustion processes in direct-injection, spark-ignition engines. A set of sub-models was developed to describe injection, atomization, breakup and wall impingement for sprays emerging from multi-hole atomizers. Furthermore, the complete evolution of the liquid fuel film was described by solving its mass, energy and momentum equations on the cylinderw wall boundaries. To model combustion, the Extended Coherent Flamelet Model (ECFM) was used in combination with a Lagrangian ignition model, describing the evolution of the flame kernel and accounting for both for flow, mixture composition and properties of the electrical circuit. The proposed approach has been implemented into the Lib-ICE code, which is based on the OpenFOAMR technology. In this paper, examples of application are provided, including the simulation of the fuel-air mixing process in a real GDI engine and the prediction of the premixed turbulent combustion process in a constant-volume vessel for different operating conditions

Development and Validation of a CFD Combustion Model for Natural Gas Engines Operating with Different Piston Bowls

Nowadays, an accurate and precise description of the combustion phase is essential in spark-ignition (SI) engines to drastically reduce pollutant and greenhouse gas (GHG) emissions and increase thermal efficiency. To this end, computational fluid dynamics (CFD) can be used to study the different phenomena involved, such as the ignition of the charge, combustion development, and pollutant formation. In this work, a validation of a CFD methodology based on the flame area model (FAM) was carried out to model the combustion process in light-duty SI engines fueled with natural gas. A simplified spherical kernel approach was used to model the ignition phase, whereas turbulent flame propagation was described through two variables. A zero-dimensional evolution of the flame kernel radius was used in combination with the Herweg and Maly formulation to take the laminar-to-turbulent flame transition into account. To estimate the chemical composition of burnt gas, two different approaches were considered—one was based on tabulated kinetics, and the other was based on chemical equilibrium. Assessment of the combustion model was first performed by using different operating points of a light-duty SI engine fueled with natural gas and by using the original piston. The results were validated by using experimental data on the in-cylinder pressure, apparent heat release rate, and pollutant emissions. Afterward, two other different piston bowl geometries were investigated to study the main differences between one solution and the others. The results showed that no important improvements in terms of combustion efficiency were obtained by using the new piston bowl shapes, which was mainly due to the very low ((Formula presented.)) or null increase in turbulent kinetic energy during the compression stroke and due to the higher heat losses ((Formula presented.)) associated with the increased surface area of the new piston geometries

Modeling an ontology on accessible evacuation routes for emergencies

Providing alert communication in emergency situations is vital to reduce the number of victims. However, this is a challenging goal for researchers and professionals due to the diverse pool of prospective users, e.g. people with disabilities as well as other vulnerable groups. Moreover, in the event of an emergency situation, many people could become vulnerable because of exceptional circumstances such as stress, an unknown environment or even visual impairment (e.g. fire causing smoke). Within this scope, a crucial activity is to notify affected people about safe places and available evacuation routes. In order to address this need, we propose to extend an ontology, called SEMA4A (Simple EMergency Alert 4 [for] All), developed in a previous work for managing knowledge about accessibility guidelines, emergency situations and communication technologies. In this paper, we introduce a semi-automatic technique for knowledge acquisition and modeling on accessible evacuation routes. We introduce a use case to show applications of the ontology and conclude with an evaluation involving several experts in evacuation procedures. © 2014 Elsevier Ltd. All rights reserved

On the use of AMSU-based products for the description of soil water content at basin scale

Abstract. Characterizing the dynamics of soil moisture fields is a key issue in hydrology, offering a strategy to improve our understanding of complex climate-soil-vegetation interactions. Besides in-situ measurements and hydrological models, soil moisture dynamics can be inferred by analyzing data acquired by sensors on board of airborne and/or satellite platforms. In this work, we investigated the use of the National Oceanic and Atmospheric Administration – Advanced Microwave Sounding Unit-A (NOAA-AMSU-A) radiometer for the remote characterization of soil water content. To this aim, a field measurement campaign, lasted about three months (3 March 2010–18 May 2010), was carried out using a portable time-domain reflectometer (TDR) to get soil water content measures over five different locations within an experimental basin of 32.5 km2, located in the South of Italy. In detail, soil moisture measurements were carried out systematically at the times of satellite overpasses, over two square areas of 400 m2, a triangular area of 200 m2 and two transects of 60 and 170 m, respectively. Each monitored site is characterized by different land covers and soil textures, to account for spatial heterogeneity of land surface. Afterwards, a more extensive comparison (i.e. analyzing a 5 yr data time series) was made using soil moisture simulated by a hydrological model. Measured and modeled soil moisture data were compared with two AMSU-based indices: the Surface Wetness Index (SWI) and the Soil Wetness Variation Index (SWVI). Both time series of indices have been filtered by means of an exponential filter to account for the fact that microwave sensors only provide information at the skin surface. This allowed to understand the ability of each satellite-based index to account for soil moisture dynamics and to understand its performances under different conditions. As a general remark, the comparison shows a higher ability of the filtered SWI to describe the general trend of soil moisture, while the SWVI can capture soil moisture variations with a precision that increases at the higher values of SWVI

A comprehensive methodology for computational fluid dynamics combustion modeling of industrial diesel engines

Combustion control and optimization is of great importance to meet future emission standards in diesel engines: increase in break mean effective pressure at high loads and extension of the operating range of advanced combustion modes seem to be the most promising solutions to reduce fuel consumption and pollutant emissions at the same time. Within this context, detailed computational fluid dynamics tools are required to predict the different involved phenomena such as fuel-air mixing, unsteady diffusion combustion and formation of noxious species. Detailed kinetics, consistent spray models and high quality grids are necessary to perform predictive simulations which can be used either for design or diagnostic purposes. In this work, the authors present a comprehensive approach which was developed using an open-source computational fluid dynamics code. To minimize the pre-processing time and preserve results' accuracy, algorithms for automatic mesh generation of spray-oriented grids were developed and successfully applied to different combustion chamber geometries. The Lagrangian approach was used to describe the spray evolution while the combustion process is modeled employing detailed chemistry and, eventually, considering turbulence-chemistry interaction. The proposed computational fluid dynamics methodology was first assessed considering inert and reacting experiments in a constant-volume vessel, where operating conditions typical of heavy-duty diesel engines were reproduced. Afterward, engine simulations were performed considering two different load points and two piston bowl geometries, respectively. Experimental validation was carried out by comparing computed and experimental data of in-cylinder pressure, heat release rate and pollutant emissions (NOx, CO and soot)

Italy-Japan agreement and discrepancies in diagnosis of superficial gastric lesions.

The agreement between Italian and Japanese endoscopists and pathologists on endoscopic and histopathological diagnoses of superficial gastric lesions is verified with the use of Paris and Vienna classifications. The correlations between Paris endoscopic types and Vienna histopathological categories is high in both the independent Italian and Japanese evaluations. However, the agreement between Italian and Japanese endoscopists is moderate due to the difficult evaluation of the height of the lesions, in particular when they are mixed. The agreement on the size of the lesions is fairly good. The probability of the same allocation to the Vienna categories of a single case is 87 per cent, disagreements remaining in dysplasia grading, between dysplasia, not only high-grade but also low-grade, and in situ carcinoma, and on cancer invasion of the lamina propria. The results indicate that use of the Paris and Vienna classifications has reduced the discrepancies between Western and Japanese endoscopists and pathologists in the diagnosis of these lesions

Efficacy of pulsatile flow perfusion in adult cardiac surgery: Hemodynamic energy and vascular reactivity

Background: The role of pulsatile (PP) versus non-pulsatile (NP) flow during a cardiopulmonary bypass (CPB) is still debated. This study’s aim was to analyze hemodynamic effects, endothelial reactivity and erythrocytes response during a CPB with PP or NP. Methods: Fifty-two patients undergoing an aortic valve replacement were prospectively randomized for surgery with either PP or NP flow. Pulsatility was evaluated in terms of energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE). Systemic (SVRi) and pulmonary (PVRi) vascular resistances, endothelial markers levels and erythrocyte nitric-oxide synthase (eNOS) activity were collected at different perioperative time-points. Results: In the PP group, the resultant EEP was 7.3% higher than the mean arterial pressure (MAP), which corresponded to 5150 ± 2291 ergs/cm3 of SHE. In the NP group, the EEP and MAP were equal; no SHE was produced. The PP group showed lower SVRi during clamp-time (p = 0.06) and lower PVRi after protamine administration and during first postoperative hours (p = 0.02). Lower SVRi required a higher dosage of norepinephrine in the PP group (p = 0.02). Erythrocyte eNOS activity results were higher in the PP patients (p = 0.04). Renal function was better preserved in the PP group (p = 0.001), whereas other perioperative variables were comparable between the groups. Conclusions: A PP flow during a CPB results in significantly lower SVRi, PVRi and increased eNOS production. The clinical impact of increased perioperative vasopressor requirements in the PP group deserves further evaluation

"The non-ischemic repair" as a safe alternative method for repair of anterior post-infarction VSD

Patient's myocardium with post-infarction ventricular septum defect (VSD) is characterized by severe dysfunction. The "additive ischemia" caused by the operating process of cross-clamp ischemia and reperfusion injury, has a significant aggravation to the myocardium and overall negative impact to patient's outcome. We present a useful, safe and advantageous methodology in order to abolish "the toxic phase" of ischemia-reperfusion which is adopted by most as the "classic repair method" of myocardial protection. This abolition is in our opinion, particularly beneficial in order to reverse postoperatively the Low Cardiac Output Syndrome (LOS) and achieve better short and long term results. By using this method we avoid the aortic occlusion, the use of systematic hypothermia and any cardioplegic arrest. Furthermore, the total cardio-pulmonary bypass (CPB) time is significantly reduced, tissue debridement and stitching is much easier and safer. We think the method is applicable for every anterior and apical case of post-infarction septum rupture. After application of method in 3 patients with anterior post-myocardial infarction VSD, we are convinced that the patient will have a better postoperative haemodynamic condition and therefore a better outcome

Comparative Analysis of Prothrombin Complex Concentrate and Fresh Frozen Plasma in the Management of Perioperative Bleeding after Coronary Artery Bypass Grafting

Background and Aim: Recent studies suggested that prothrombin complex concentrate (PCC) might be more effective than fresh frozen plasma (FFP) to reduce red blood cell (RBC) transfusion requirement after cardiac surgery. The benefits and risks associated with the use of PCC over FFP have been investigated in this study including patients undergoing isolated coronary artery bypass grafting(CABG) from a prospective, multicenter registry. Methods: This is a comparative analysis of 416 patients who received postoperatively FFP and 119 patients who received PCC with or without FFP after isolated CABG. Results: Mixed-effects regression analyses adjusted for multiple covariates and participating centers showed that PCC significantly decreased RBC transfusion (67.2% vs. 87.5%, adjusted OR 0.319, 95%CI 0.136-0.752) and platelet transfusion requirements (11.8% vs. 45.2%, adjusted OR 0.238, 95%CI 0.097-0.566) compared with FFP. The PCC cohort received a mean of 2.7\ub13.7 (median, 2.0, IQR 4) units of RBC and the FFP cohort received a mean of 4.9\ub16.3 (median, 3.0, IQR 4) units of RBC (adjusted coefficient, -1.926, 95%CI -3.357-0.494). The use of PCC increased the risk of KDIGO acute kidney injury (41.4% vs. 28.2%, adjusted OR 2.300, 1.203-4.400), but not of KDIGO acute kidney injury stage 3 (6.0% vs. 8.0%, OR 0.850, 95%CI 0.258-2.796) when compared with the FFP cohort. Conclusions: These results suggest that the use of PCC compared with FFP may reduce the need of blood transfusion after CABG. In view of the observational nature of this study, these results shoul