Evaluation of DC-link voltage ripple in five-phase PWM voltage source inverters

This paper presents the analysis of the DC-link voltage switching ripple in five-phase PWM voltage source inverters with balanced load. The analysis is particularly important for the design and selection of a DC-link capacitor making it possible to meet desired electrical performance of the inverter system. Simple and practical equation for designing the DC-link capacitor is proposed relating the value of capacitance to the maximum value (peak-to-peak) of the DC-link voltage ripple. The amplitude of the DC-link voltage switching ripple is analytically derived as a function of modulation index, and the amplitude of the output current and phase angle. In order to show peak-to-peak voltage ripple distribution, different diagrams are introduced. Reference is made to continuous symmetric centred PWM modulation (i.e., space vector modulation SVM). In order to verify proposed developments, simulations have been carried out by Matlab/Simulink considering full range of modulation index and output phase angle

Prédiction de la profondeur de sol humidifié sous goutteur

A partir de résultats expérimentaux, des équations d'infiltration et de continuité, nous avons établi une équation permettant de prédire la profondeur maximale humidifiée par un goutteur à la surface du sol. Connaissant l'humidité initiale du sol Øi, la conductivité hydraulique Kf et la teneur en eau au niveau du front Øi ; l'équation établie permet de calculer la profondeur du front d'humectation Zf(t) à partir du suivi du rayon du front d'humectation Rf(t) à la surface du sol. Pour tester la validité de cette nouvelle approche, des essais ont été menés sur deux types de sol (sableux et limono-argileux) et avec trois débits différents. Les valeurs de Zf(t) mesurées (par deux techniques différentes) ont été comparées à celles calculées par cette équation, les résultats étaient, dans tous les cas, quasi-identiques (coefficient de corrélation R2, dans tous les cas, supérieur ou égal à 0.94).In trickle irrigation, the wetted soil volume fraction (P) is a fundamental parameter for both network design and irrigation scheduling. However, methods used to determine such parameter (P) are still limited and unaccurate. Further, numerical models established for predicting wetted soil volume (or bulb) dimensions remain onerous, complex, expensive, and therefore hardly used. Experimental and numerical results performed on water infiltration from point source on the soil surface show a close relationship between the horizontal and vertical bulb dimensions. This study which was based on continuity and cumulative infiltration equations allowed to establish a new and simple equation for predicting wetted soil depth. This equation enables, knowing initial and wetting front water content and K(hf) (soil hydraulic conductivity on the wetting front), to calculate the front depth Zf(t) beneath a point source with only measuring the front radius Rf(t) on the soil surface. The established equation verifies physical conditions of axisymmetric water infiltration into the soil. The established equation was tested by performing trials on two different soil types and three discharge rates. Two different procedures were simultaneously used for determining Rf(t) and Zf(t). i) observing bulb dimensions evolution on the soil surface and along the symmetry axis. ii) Rf(t) and Zf(t) values were inferred from the horizontal and vertical suction profiles respectively. The Zf(t) values calculated, using such equation, are compared with those measured. The results obtained showed good agreement between calculated and measured data (R2 >=0.94). This study was performed during an axisymmetric water infiltration into bare, homogeneous, and isotropic soil. It needs to be extended to heteregeneous, anisotropic and cultivated soils

Formation of Pancreatoduodenal Fistula in Intraductal Papillary Mucinous Neoplasm of the Pancreas Decreased the Frequency of Recurrent Pancreatitis

Intraductal papillary mucinous neoplasms (IPMN) of the pancreas are characterized by proliferation of mucin-secreting cells in the main pancreatic duct (PD) or its branches. The secreted thick mucin usually leads to PD obstruction and dilation. A common complication of IPMN is recurrent acute pancreatitis secondary to poor pancreatic fluid drainage, and rarely, pancreatobiliary and pancreatointestinal fistulae. We describe a unique case of IPMN in a 57-year-old male who was referred to our institution for evaluation of recurrent acute pancreatitis. After extensive evaluation, he was diagnosed with main duct IPMN. Intraductal PD biopsy revealed intestinal type IPMN with intermediate grade dysplasia. Patient was managed clinically by large caliber (10 French) PD stenting which eliminated his recurrent acute pancreatitis. The patient was initially referred for pancreatic resection; however, surgery was aborted and evaluated to be high risk with high morbidity secondary to the extensive adhesions between the pancreas and surrounding structures. Patient remained clinically stable for a few years except for an episode of acute pancreatitis that happened after a trial of stent removal. Subsequently, the patient did well after the PD stent was replaced. Recently, repeat abdominal imaging revealed a large pancreatoduodenal fistula which was confirmed on repeat endoscopic retrograde cholangiopancreatography. We were able to perform pancreatoscopy by advancing a regular upper scope through the fistula and into the PD. Interestingly, the fistula relieved the symptoms of obstruction and subsequently decreased the frequency of recurrent pancreatitis episodes with no further episodes at 6 months follow-up. This case highlights the importance of providing adequate PD drainage to reduce the frequency of recurrent acute pancreatitis in the setting of main duct IPMN, especially if the patient is not a surgical candidate. Also, physicians need to monitor for complications such as fistula formation between the pancreas and surrounding structures in the setting of chronic inflammation due to recurrent episodes of pancreatitis. Early identification of a fistula is important for surgical planning. Furthermore, since recent studies suggested a higher incidence of additional primary malignancies in patients with IPMN of the pancreas compared to the general population, patients may be considered for screening for other primary malignancies

Global Observer for Homogegeous Vector Fields

This paper presents an algebraic approach to the problem of nonlinear observer design. We show, that an observer which converges globally and asymptotically can be designed for a class of homogeneous systems of odd degree

Exploring end of life priorities in Saudi males: usefulness of Q-methodology

Sorting Sheet & Instructions. (DOC 50 kb

Circle and Popov Criterion for Output Feedback Stabilization of Uncertain Systems

In this paper, we address the problem of output feedback stabilization for a class of uncertain dynamical systems. An asymptotically stabilizing controller is proposed under the assumption that the nominal system is absolutely stable

MEASUREMENT OF CORTISOL AND CORTISONE IN HUMAN SALIVA BY UPLC-MS/MS

Objective: To develop and validate a simple and rapid assay for simultaneous measurement of cortisol and cortisone in human saliva by ultra-performance liquid chromatography-tandem mass spectrometry. Methods: Chromatographic analysis was performed on an Atlantis dC18 column (2.1 x 100 mm, 3 µm) using a mobile phase consisting of acetonitrile and 2 mmol ammonium-acetate (50:50, v; v) that was delivered at a flow rate of 0.3 ml/min. The eluents were monitored using electrospray ionization in the positive ion mode set at transition set of mass-to-charge (m/z): 363.11 → 121.00, 361.18 → 163.11, and 367.19 → 121.24 for cortisol, cortisone and internal standard (IS), respectively the method was validated for linearity, accuracy, precision, and recovery, according to international guidelines. Results: The retention times of cortisol, cortisone and internal were about 1.38, 1.43 and 1.38 min, respectively. Cortisol level and cortisone level relationship to the ratio of their respective peak-area to IS’s peak-area was linear (range of 0.5-100 ng/ml). Coefficients of variation and inaccuracy were, ≤9.9% and-0.3 to 6.9 for cortisol and ≤8.4 and-1.5 to 4.8 for cortisone, respectively. Extraction recoveries for cortisol, cortisone, and the IS were 90%, 94%, and 98%, respectively. Cortisol and cortisone stability was evaluated in processed saliva samples (stored at room temperature for 24 h) and unprocessed saliva samples (stored at room temperature for 24 h or at-20 °C for 10 w) and after 3 freeze-thaw cycles was ≥ 86%. Conclusion: The proposed method is simple, precise, and accurate for the rapid simultaneous measurement of cortisol and cortisone levels in saliva. The assay was successfully applied to determine levels of cortisol and cortisone in human saliva samples obtained from healthy volunteers

L’endocardite à Bartonella en Tunisie: Particularités lésionnelles et évolutives

L'endocardite à Bartonalla est une infection ubiquitaire, son diagnostic est difficile vu qu'il s'agit souvent d'endocardite à hémoculture négative. Lebut de cette étude est d'analyser les particularités lésionnelles et  évolutives de cette entité dans un pays du nord d'Afrique, la Tunisie et dedémontrer la gravité de cette infection. Nous avons étudié  rétrospectivement les dossiers médicaux de 20 patients atteints  d'endocardite à Bartonella, confirmée selon les critères de Dukes modifiés. L'âge moyen de nos patients était 37 ans avec une prédominance  masculine (SR=3). Tous nos malades avaient un niveau socio-économique bas. Le motif essentiel de consultation était la dyspnée, 6 patients étaient admis dans un tableau d'insuffisance cardiaque congestive. Une  prédilection des lésions au niveau de la valve aortique a été notée (14 cas). Quatorze patients avaient des végétations endocarditiques avec une taille qui dépasse 10 mm chez 8 malades. La majorité des patients (18 patients) présentaient une régurgitation valvulaire massive en rapport principalement avec des mutilations importantes (6 cas de ruptures de cordages mitraux, 2 cas de déchirures des sigmoïdes aortiques, un cas de perforation valvulaire aortique, un cas de désinsertion de prothèse  mitrale). Quinze malades (3/4) avaient nécessité une chirurgie à la phase active de la maladie, l'indication majeure était l'insuffisance cardiaque. Une complication neurologique était notée chez 2 malades et une  complication rénale chez 3 malades. Treize patients étaient guéris, 5 malades étaient décédés et 2 malades opérés ont présenté une  réinfection à staphylococcus aureus et à candida albicans en  postopératoire. L'endocardite à Bartonella est une infection grave. Cette Bactérie possède un potentiel destructif important. Le recours à la chirurgie est quasi constant. La morbi-mortalité est élevée. La recherche de cette bactérie devrait être alors systématique chez nos malades suspects d'endocardite d'autant plus que la bartonellose est endémique sur nos terres

Quantitative analysis of cell organization in the external region of the olive fruit

Definitions of the cells that constitute the exocarp or exterior tissue of fleshy fruits are often vague, sometimes providing contradictory descriptions of the epidermis plus none or varying numbers of underlying cell layers for the same species. This study uses a morphometric approach to investigate how cell dimensions, cell number, and their relation with genetically based fruit size differences can contribute to a characterization of tissue organization in the external fruit region, using the olive drupe as an example.We determined cell area, radial and tangential widths, and cell number in the epidermis and 20 subepidermal cell layers of mature fruits of four olive cultivars that range in fruit size. Variation of these measurements among cell layers and the implied cellular contributions to fruit expansion revealed two different subepidermal regions, but with constant widths and layer numbers for all cultivars: (1) the first four cell layers (1-4), which have similar behavior to the epidermis; and (2) the following five cell layers (5-9), which are more similar to the mesocarp. The results provide new insights about cell patterns in the external region of the olive fruit and suggest that layers 1-4 together with the epidermis may act as a multiseriate exocarp and layers 5-9 may act as an outer mesocarp. © 2012 by The University of Chicago. All rights reserved.The study was funded by the Ministry of Science and Innovation of Spain and European Research and Development Funds (grant AGL2009-07248).Peer Reviewe