On the reliability of electrical drives for safety-critical applications

The aim of this work is to present some issues related to fault tolerant electric drives,which are able to overcome different types of faults occurring in the sensors, in thepower converter and in the electrical machine, without compromising the overallfunctionality of the system. These features are of utmost importance in safety-criticalapplications. In this paper, the reliability of both commercial and innovative driveconfigurations, which use redundant hardware and suitable control algorithms, will beinvestigated for the most common types of fault: besides standard three phase motordrives, also multiphase topologies, open-end winding solutions, multi-machineconfigurations will be analyzed, applied to various electric motor technologies. Thecomplexity of hardware and control strategies will also be compared in this paper, sincethis has a tremendous impact on the investment costs

Power Loss Modelling of GaN HEMT based 3L ANPC Three Phase Inverter for different PWM Techniques

The paper presents a straightforward modelling approach to compute the power loss distribution in GaN HEMT based three phase and three level (3L) active neutral point clamped (ANPC) inverters, for different pulse width modulated techniques. Conduction and switching losses averaged over each PWM switching period are analytically computed by starting from the operating conditions of the AC load and data of GaN power devices. The accuracy of the proposed analytical approach is evaluated through a circuit based power electronics simulation tool, applied to different carrier-based PWM strategies.Comment: 10 pages, 13 figures, 24th European Conference on Power Electronics and Applications ( IEEE EPE 2022 ECCE Europe). This work has been carried out in the framework of the ECSEL-JU Project GaN4AP (Gallium Nitride for Advanced Power Applications) - Grant Agreement No.10100731

The Hepatologist in the Haematologist Field: a Rare Cause of Non-Cirrhotic Portal Hypertension

An 81 year-old gentleman was admitted to the emergency department of our hospital due to hematemesis and melena, and endoscopic evidence of portal hypertension. Due to presence of ascites and esophageal varices he was referred to gastroenterology care. His history included systemic mastocytosis, and biochemistry showed marked cholestasis with normal liver function tests. Clinical work-up was not consistent with liver disease-related portal hypertension, but rather hepatic involvement of systemic mastocytosis and the development of non-cirrhotic portal hypertension. This clinical case highlights that although systemic mastocytosis is uncommon, the subsequent development of liver involvement and non-cirrhotic portal hypertension are complications of the disease that need always be considere

Factors predicting survival in patients with locally advanced pancreatic cancer undergoing pancreatectomy with arterial resection

Pancreatectomy with arterial resection is a treatment option in selected patients with locally advanced pancreatic cancer. This study aimed to identify factors predicting cancer-specific survival in this patient population. A single-Institution prospective database was used. Pre-operative prognostic factors were identified and used to develop a prognostic score. Matching with pathologic parameters was used for internal validation. In a patient population with a median Ca 19.9 level of 19.8 U/mL(IQR: 7.1–77), cancer-specific survival was predicted by: metabolic deterioration of diabetes (OR = 0.22, p = 0.0012), platelet count (OR = 1.00; p = 0.0013), serum level of Ca 15.3 (OR = 1.01, p = 0.0018) and Ca 125 (OR = 1.02, p = 0.00000137), neutrophils-to-lymphocytes ratio (OR = 1.16; p = 0.00015), lymphocytes-to-monocytes ratio (OR = 0.88; p = 0.00233), platelets-to-lymphocytes ratio (OR = 0.99; p = 0.00118), and FOLFIRINOX neoadjuvant chemotherapy (OR = 0.57; p = 0.00144). A prognostic score was developed and three risk groups were identified. Harrell’s C-Index was 0.74. Median cancer-specific survival was 16.0 months (IQR: 12.3–28.2) for the high-risk group, 24.7 months (IQR: 17.6–33.4) for the intermediate-risk group, and 39.0 months (IQR: 22.7–NA) for the low-risk group (p = 0.0003). Matching the three risk groups against pathology parameters, N2 rate was 61.9, 42.1, and 23.8% (p = 0.04), median value of lymph-node ratio was 0.07 (IQR: 0.05–0.14), 0.04 (IQR:0.02–0.07), and 0.03 (IQR: 0.01–0.04) (p = 0.008), and mean value of logarithm odds of positive nodes was − 1.07 ± 0.5, − 1.3 ± 0.4, and − 1.4 ± 0.4 (p = 0.03), in the high-risk, intermediate-risk, and low-risk groups, respectively. An online calculator is available at www.survivalcalculator-lapdac-arterialresection.org. The prognostic factors identified in this study predict cancer-specific survival in patients with locally advanced pancreatic cancer and low Ca 19.9 levels undergoing pancreatectomy with arterial resection

Comparison of an X-ray selected sample of massive lensing clusters with the MareNostrum Universe LCDM simulation

A long-standing problem of strong lensing by galaxy clusters regards the observed high rate of giant gravitational arcs as compared to the predictions in the framework of the "standard" cosmological model. Recently, few other inconsistencies between theoretical expectations and observations have been claimed which regard the large size of the Einstein rings and the high concentrations of few clusters with strong lensing features. All of these problems consistently indicate that observed galaxy clusters may be gravitational lenses stronger than expected. We use clusters extracted from the MareNostrum Universe to build up mock catalogs of galaxy clusters selected through their X-ray flux. We use these objects to estimate the probability distributions of lensing cross sections, Einstein rings, and concentrations for the sample of 12 MACS clusters at $z>0.5$ presented in Ebeling et al. (2007) and discussed in Zitrin et al. (2010). We find that simulated clusters produce $\sim 50$ less arcs than observed clusters do. The medians of the distributions of the Einstein ring sizes differ by $\sim 25$ between simulations and observations. We estimate that, due to cluster triaxiality and orientation biases affecting the lenses with the largest cross sections, the concentrations of the individual MACS clusters inferred from the lensing analysis should be up to a factor of $\sim 2$ larger than expected from the $\Lambda$CDM model. The arc statistics, the Einstein ring, and the concentration problems in strong lensing clusters are mitigated but not solved on the basis of our analysis. Nevertheless, due to the lack of redshifts for most of the multiple image systems used for modeling the MACS clusters, the results of this work will need to be verified with additional data. The upcoming CLASH program will provide an ideal sample for extending our comparison (abridged).Comment: 11 pages, 9 figures, accepted for publication on A&

Strong lensing in the MareNostrum Universe: biases in the cluster lens population

Strong lensing is one of the most direct probes of the mass distribution in the inner regions of galaxy clusters. It can be used to constrain the density profiles and to measure the mass of the lenses. Moreover, the abundance of strong lensing events can be used to constrain the structure formation and the cosmological parameters through the so-called "arc-statistics" approach. However, several issues related to the usage of strong lensing clusters in cosmological applications are still controversial, leading to the suspect that several biases may affect this very peculiar class of objects. With this study we aim at better understanding the properties of galaxy clusters which can potentially act as strong lenses. We do so by investigating the properties of a large sample of galaxy clusters extracted from the N-body/hydrodynamical simulation MareNostrum Universe. We explore the correlation between the cross section for lensing and many properties of clusters, like the mass, the three-dimensional and projected shapes, their concentrations, the X-ray luminosity and the dynamical activity. We find that the probability of strong alignments between the major axes of the lenses and the line of sight is a growing function of the lensing cross section. In projection, the strong lenses appear rounder within R200, but we find that their cores tend to be more elliptical as the lensing cross section increases. We also find that the cluster concentrations estimated from the projected density profiles tend to be biased high. The X-ray luminosity of strong lensing clusters is higher than that of normal lenses of similar mass and redshift. This is particular significant for the least massive lenses. Finally, we find that the strongest lenses generally exhibit an excess of kinetic energy within the virial radius, indicating that they are more dynamically active than usual clusters.Comment: 22 pages, 18 figures, accepted for publication on A&

Constraints on the shapes of galaxy dark matter haloes from weak gravitational lensing

We study the shapes of galaxy dark matter haloes by measuring the anisotropy of the weak gravitational lensing signal around galaxies in the second Red-sequence Cluster Survey (RCS2). We determine the average shear anisotropy within the virial radius for three lens samples: all galaxies with 19<m_r'<21.5, and the `red' and `blue' samples, whose lensing signals are dominated by massive low-redshift early-type and late-type galaxies, respectively. To study the environmental dependence of the lensing signal, we separate each lens sample into an isolated and clustered part and analyse them separately. We also measure the azimuthal dependence of the distribution of physically associated galaxies around the lens samples. We find that these satellites preferentially reside near the major axis of the lenses, and constrain the angle between the major axis of the lens and the average location of the satellites to =43.7 deg +/- 0.3 deg for the `all' lenses, =41.7 deg +/- 0.5 deg for the `red' lenses and =42.0 deg +/- 1.4 deg for the `blue' lenses. For the `all' sample, we find that the anisotropy of the galaxy-mass cross-correlation function =0.23 +/- 0.12, providing weak support for the view that the average galaxy is embedded in, and preferentially aligned with, a triaxial dark matter halo. Assuming an elliptical Navarro-Frenk-White (NFW) profile, we find that the ratio of the dark matter halo ellipticity and the galaxy ellipticity f_h=e_h/e_g=1.50+1.03-1.01, which for a mean lens ellipticity of 0.25 corresponds to a projected halo ellipticity of e_h=0.38+0.26-0.25 if the halo and the lens are perfectly aligned. For isolated galaxies of the `all' sample, the average shear anisotropy increases to =0.51+0.26-0.25 and f_h=4.73+2.17-2.05, whilst for clustered galaxies the signal is consistent with zero. (abridged)Comment: 28 pages, 23 figues, accepted for publication in A&

Quantifying the effect of baryon physics on weak lensing tomography

We use matter power spectra from cosmological hydrodynamic simulations to quantify the effect of baryon physics on the weak gravitational lensing shear signal. The simulations consider a number of processes, such as radiative cooling, star formation, supernovae and feedback from active galactic nuclei (AGN). Van Daalen et al. (2011) used the same simulations to show that baryon physics, in particular the strong feedback that is required to solve the overcooling problem, modifies the matter power spectrum on scales relevant for cosmological weak lensing studies. As a result, the use of power spectra from dark matter simulations can lead to significant biases in the inferred cosmological parameters. We show that the typical biases are much larger than the precision with which future missions aim to constrain the dark energy equation of state, w_0. For instance, the simulation with AGN feedback, which reproduces X-ray and optical properties of groups of galaxies, gives rise to a ~40% bias in w_0. We demonstrate that the modification of the power spectrum is dominated by groups and clusters of galaxies, the effect of which can be modelled. We consider an approach based on the popular halo model and show that simple modifications can capture the main features of baryonic feedback. Despite its simplicity, we find that our model, when calibrated on the simulations, is able to reduce the bias in w_0 to a level comparable to the size of the statistical uncertainties for a Euclid-like mission. While observations of the gas and stellar fractions as a function of halo mass can be used to calibrate the model, hydrodynamic simulations will likely still be needed to extend the observed scaling relations down to halo masses of 10 ^12 M_sun/h.Comment: 17 pages, 14 Figures, MNRAS accepted. Small changes to the published version: typos in Eq. 4 corrected, Figure 2 updated (y-ticks of the previous version were wrong). Bibliography updated with published papers when possibl

Cosmological Galaxy Formation Simulations Using SPH

We present the McMaster Unbiased Galaxy Simulations (MUGS), the first 9 galaxies of an unbiased selection ranging in total mass from 5$\times10^{11}$ M$_\odot$ to 2$\times10^{12}$ M$_\odot$ simulated using n-body smoothed particle hydrodynamics (SPH) at high resolution. The simulations include a treatment of low temperature metal cooling, UV background radiation, star formation, and physically motivated stellar feedback. Mock images of the simulations show that the simulations lie within the observed range of relations such as that between color and magnitude and that between brightness and circular velocity (Tully-Fisher). The greatest discrepancy between the simulated galaxies and observed galaxies is the high concentration of material at the center of the galaxies as represented by the centrally peaked rotation curves and the high bulge-to-total ratios of the simulations determined both kinematically and photometrically. This central concentration represents the excess of low angular momentum material that long has plagued morphological studies of simulated galaxies and suggests that higher resolutions and a more accurate description of feedback will be required to simulate more realistic galaxies. Even with the excess central mass concentrations, the simulations suggest the important role merger history and halo spin play in the formation of disks.Comment: 16 pages, 16 figures, submitted to MNRAS, movies available at http://mugs.mcmaster.ca . Comments welcome