311 research outputs found
Caractérisation de l'impact rénal à court et long terme du choc hémorragique expérimental murin
No full textLa présence d'une insuffisance rénale aiguë (IRA) est un marqueur indépendant de surmortalité dans de nombreuses pathologies médico-chirurgicales. La première cause d'IRA organique est la nécrose tubulaire aiguë ischémique (NTAI). L'absence d'efficacité, chez l'Homme, des thérapeutiques pourtant testées avec succès chez l'animal pourrait être liée aux carences des modèles expérimentaux de nécrose tubulaire. En effet, ces modèles (clampage artère rénale, dose massive de drogues tubulo-toxiques) proposent une approche caricaturale de l'IRA qui prévient tout mécanisme physiologique d'adaptation. Notre objectif était d'élaborer un nouveau modèle d'IRA par choc hémorragique à pression contrôlée chez la souris C57/Bl6 et d'en étudier les conséquences rénales. Nous avons dans un premier temps mis au point le modèle de choc hémorragique et montré qu'une durée de choc de deux heures à 35 mmHg de pression artérielle moyenne est susceptible de créer une IRA par NTAI. Nous avons dans un deuxième temps étudié les répercussions rénales de ce choc et ainsi observé un impact fonctionnel moléculaire et structurel prédominant entre le 2ème jour (J) et J6 en post choc mais persistant à J21 avec la mise en évidence d'une fibrose rénale et d'anomalies fonctionnelles physiologiques tubulaires rénales. L'existence d'une hypoxie rénale dans les suites du choc nous a amené à étudier son impact dans une population de souris diabétiques de type 2 obèse (db/db). Nous avons en effet confirmé que les reins de souris diabétiques présentaient une hypoxie avant toute agression et que le choc hémorragique aboutissait à un impact fonctionnel plus sévère et une réponse à l'hypoxie différente chez les souris diabétiques. Enfin, la difficulté d'évaluation de la fonction de filtration rénale chez le muridé nous a conduits à effectuer une étude de corrélation entre les marqueurs historiques (créatininémie, urée plasmatique), la cystatine C et le gold standard (la clearance de l'inuline plasmatique) chez 80 souris. Dans cette note technique située en annexe, nous avons pu confirmer que ni l'urée ni la créatininémie par la technique colorimétrique n'étaient des marqueurs fiables chez la souris. La créatininémie par la technique immunoenzymatique et surtout la cystatine c sont mieux corrélées au DFG évalué par la clearance de l'inuline. Au total nous avons décrit un nouveau modèle d'agression rénale chez des souris sauvages C57/Bl6 et une population de souris diabétiques de type 2. Nous avons également mis en évidence l'intérêt de la cystatine C chez la souris en tant que marqueur d'estimation du DFG a contrario des marqueurs historiques (créatininémie par la technique colorimétrique et urée plasmatique).Acute renal failure (ARF) is an independent mortality marker in numerous medical or surgical pathologies. The leading cause of organic ARF is ischemic acute tubular necrosis. The lack of efficacy in humans of therapeutic yet successfully tested in animals may be related to the deficiencies in experimental models of tubular necrosis. Indeed, these models (renal artery clamping, massive dose of tubulo-toxic drugs) propose a caricatural mechanism of ARF and prevent any physiological mechanism of adaptation. Our goal was to develop, in mice, a new model of ARF induced by pressure controlled hemorrhagic shock and to decipher its kidney impact. We initially developed the model of hemorrhagic shock and showed that two hours shock duration at 35 mmHg of mean arterial pressure is likely to create an organic ARF. Then, we tested the impact of this shock on kidney and observed a molecular and functional impact predominant between day (D) 2 and D6 after shock but still present at D21 with renal fibrosis and renal tubular dysfunction. The existence of renal hypoxia in the aftermath of shock led us to study its impact in a population of obese type 2 diabetic mice (db/db). We have indeed confirmed that diabetic mice kidneys already exhibit hypoxia before any aggression and that hemorrhagic shock led to a more severe functional impact and a different response to hypoxia in diabetic mice. At least, because evaluating glomerular filtration (GFR) in mice is hazardous, we have performed a correlation study between the historical markers (serum creatinin, plasma urea), cystatin c and measured GFR. We have confirmed that neither urea nor creatinin obtained by the colorimetric technique are reliable markers in mice. Nevertheless, creatinin obtained by immuno colorimetric assay and particularly cystatin C are better correlated with measured GFR. Altogether, we have described a new model of ARF in two different mice populations: control C57/Bl6 and type 2 diabetic obese mice. We also highlight that cystatin C in mice is more accurate for estimating GFR that historical markers (serum creatinin by the colorimetric technique and plasma urea)
Intrathoracic blood volume and global end-diastolic volume should be included among indexes used in intensive care for assessment of fluid responsiveness in spontaneously breathing patients : The authors reply
No full textReply to : Perel A. Intrathoracic blood volume and global end-diastolic volume should be included among indexes used in intensive care for assessment of fluid responsiveness in spontaneously breathing patients. Crit Care Med. 2006 Aug;34(8):2266-7; author reply 2267. doi: 10.1097/01.CCM.0000229645.81370.B8. PMID: 16883213, which is a comment on : Coudray A, Romand JA, Treggiari M, Bendjelid K. Fluid responsiveness in spontaneously breathing patients: a review of indexes used in intensive care. Crit Care Med. 2005 Dec;33(12):2757-62. doi: 10.1097/01.ccm.0000189942.24113.65. PMID: 16352956., accessible on : https://archive-ouverte.unige.ch/unige:182470</a
Short-Circuit Calculations in LV Cold Ironing Systems: Characteristic Currents Method CCM and IEC Method
No full textThis paper presents the calculation procedure of short
circuits adopting the CCM “Characteristic Currents Method”.
In a previous paper by the author Parise, the CCM has been
upgraded with the introduction of "characteristic"
countercurrents and the generalization of the Kirchhoff laws.
For illustrating the calculation procedure, the selected case study
deals with a low voltage cold ironing system where multiple ships
are allowed to operate simultaneously on one shore power
transformer and, so, a comparison has been developed between
the IEC approach of the short-circuit calculation and the CCM
CEAI: CCM-based email authorship identification model
No full textIn this paper we present a model for email authorship identification (EAI) by employing a Cluster-based Classification (CCM) technique. Traditionally, stylometric features have been successfully employed in various authorship analysis tasks; we extend the traditional feature set to include some more interesting and effective features for email authorship identification (e.g., the last punctuation mark used in an email, the tendency of an author to use capitalization at the start of an email, or the punctuation after a greeting or farewell). We also included Info Gain feature selection based content features. It is observed that the use of such features in the authorship identification process has a positive impact on the accuracy of the authorship identification task. We performed experiments to justify our arguments and compared the results with other base line models. Experimental results reveal that the proposed CCM-based email authorship identification model, along with the proposed feature set, outperforms the state-of-the-art support vector machine (SVM)-based models, as well as the models proposed by Iqbal et al. (2010, 2013) [1,2]. The proposed model attains an accuracy rate of 94% for 10 authors, 89% for 25 authors, and 81% for 50 authors, respectively on Enron dataset, while 89.5% accuracy has been achieved on authors’ constructed real email dataset. The results on Enron dataset have been achieved on quite a large number of authors as compared to the models proposed by Iqbal et al. [1,2]
Single-Inductor, Dual-Input CCM Boost Converter for Multi-Junction PV Energy Harvesting
Full text linkabstract: This thesis presents a power harvesting system combining energy from sub-cells of
multi-junction photovoltaic (MJ-PV) cells. A dual-input, inductor time-sharing boost
converter in continuous conduction mode (CCM) is proposed. A hysteresis inductor current
regulation in designed to reduce cross regulation caused by inductor-sharing in CCM. A
modified hill-climbing algorithm is implemented to achieve maximum power point
tracking (MPPT). A dual-path architecture is implemented to provide a regulated 1.8V
output. A proposed lossless current sensor monitors transient inductor current and a time-based power monitor is proposed to monitor PV power. The PV input provides power of
65mW. Measured results show that the peak efficiency achieved is around 85%. The
power switches and control circuits are implemented in standard 0.18um CMOS process.Dissertation/ThesisMasters Thesis Engineering 201
Preparation and characterization of catalyst-coated membrane (CCM) for proton exchange mebrane fuel cells
No full textGlobal energy consumption has been escalating over the years as the more and more countries are moving into the manufacturing industry. Growing affluence of developed countries has also resulted in an increased demand of electricity. Demands for more energy from alternative sources is required as oil, natural gas and coal are set to peak and go into decline within the next decade and no technology can change that As such, intensive research has been done on clean alternative energy source[1], in particular Proton Exchange Membrane Fuel Cell (PEMFC) as it has high efficiency and has high potential as an alternative energy source[2, 3].
In this report, the author will be covering technology behind PEMFC and its fabrication process. The conventional method of assembling PEMFC involves Membrane Electrode Assembly (MEA) assembled by Proton Exchange Membrane (PEM) and Electrodes coated with catalyst. The final year project was conducted to investigate the novel procedure and the efficiency of the new Catalyst Coated Membrane (CCM) fabricated using the recasting CCM method, discover the effects of varying thickness of the Nafion® membrane and the effects of Hot-pressing of the Nafion® membrane on the performance of the home-made CCM, which is prepared one layer by one layer.
Various experiments were conducted to measure the effects of the varying Nafion® membrane thickness and hot-pressing to obtain a suitable CCM for use in fuel cells.Bachelor of Engineering (Mechanical Engineering
Lunar Rover Power Electronic System
No full textThe small, light-weight and modular Lunar rover must survive several earth days in harsh environment after its moon landing. Its power electronic system with integrated solar generation needs power for its mission and also to stay warm in very cold temperatures of the moon. This paper presents the design of the power electronic system of the Lunar Zebro rover. Two topologies are compared that result from using a 12 V bus and 24 V bus. The design of the DC/DC converters required is presented for CCM and DCM operation. The losses in the DC/DC converters operating in CCM and DCM are calculated for the two bus voltages to determine the mode of operation and bus voltage that results in the highest efficiency. Further, the average power loss during operation of the rover is estimated for both bus voltages. Operating the DC/DC converters in CCM using a 12 V bus results in the lowest losses.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ESP LABDC systems, Energy conversion & Storag
An underpinning theory and approach to applicability testing of constructive computational mechanisms
No full textApplicability testing of constructive computational mechanisms (CCMs) is a new challenge for both the academia and the industry. The overwhelming majority of the existing validation approaches focuses on the internal validity of CCMs (e.g. consistency, bias), while there is a shortage of efficient approaches for assessing the external validity (e.g. applicability, reusability). The objective of this paper is to clarify the concepts and criteria, and to develop an approach for a systematic evaluation of the applicability of a given CCM to cases that were not considered at design time. The approach is adapted from the validation square approach (VSA). The adapted methodology (A-VSA) makes it possible to evaluate CCMs from (a) theoretical structural, (b) empirical structural, (c) theoretical performance, and (d) empirical performance dimensions. Altogether eight indicators are introduced that support the evaluation process. The effectiveness of the A-VSA was confirmed through a case study, in which a specific CCM is considered and the strategy of the A-VSA was operationalized with three completely different application cases. As evidenced by the results, the proposed A-VSA establishes a tight coupling among the enablers embraced by a CCM and the aspects of theoretical and empirical validation, which approves the approach to be an efficient tool for defining the range and/or the extent of applicability. The advantage of the A-VSA is that it offers a way to transfer qualitative applicability evaluation into quantitative applicability assessment, which allows the use of both subjective statements and mathematical modeling in applicability testing. The results of the assessment can guide the adaptation work of a CCM when applied to an out-of-domain application.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Cyber-Physical SystemsInternet of Thing
Multi-IP-Based SoC Design Including CCM Security Mode of Operation By
No full textI hereby declare that I am the sole author of this thesis. I authorize the University of Waterloo and KTH University to lend this thesis to other institutions or individuals for the purpose of scholarly research. I further authorize the University of Waterloo and KTH University to reproduce this thesis by photocopying or by other means, in total or in print, at the request of other institutions is individuals for the purpose of scholarly research. ii Embedding security in many mobile electronic devices is of great importance. With the emergence of powerful self-contained FPGAs which include microprocessors, memory etc. for SoC designs, it has shifted focus to these programmable platforms. A co-design approach can be used to optimize speed, area and power consumption by partitioning function onto the on-chip microprocessor and programmable logic blocks. FPGAs typically provide higher efficiency compared to software. On the other hand they offer more flexibility and much lower design and debug costs compared to specifically-built hardware. This thesis mainly implements CCM security mode of operation on a FPGA platform by using the AES encryption algorithm, it then builds a complete SoC that is based on multi IP cores including CCM. Except for the hard on-chip IP cores (i.e. microprocessors and memory), the device controllers, the PLB and OPB buses and CCM are all soft IP peripherals to build a complex system. The idea of building the elements as soft IP cores makes it very easy for further on-chip developments or modifications. The CCM core that sits on the same PLB bus at 80 MHz, can easily communicate with PowerPC or DDR SDRAM or BRAM controllers which are on the same bus. The implementation exploits iterative structure of AES to save the hardware resources; it implements the key expansion core as well. It also reports on the challenges and problems throughout the implementation. ii
A Reliability Prediction for Integrated LED Lamp with Electrolytic Capacitor-Free Driver
No full textThis paper studies the interaction of catastrophic failure of the driver and LED luminous flux decay for an integrated LED lamp with an electrolytic capacitor-free LED driver. Electronic thermal simulations are utilized to obtain the lamp's dynamic history of temperature and current for two distinct operation modes: constant current mode (CCM) and constant light output (CLO) mode, respectively. Driver's mean time to failure (MTTF) and the LED's lifetime in terms of luminous flux are calculated. Under CLO mode, the LED's current increases exponentially to maintain the constant light output. As a result, the junction temperatures of LEDs, MOSFETs, and power diodes in driver rise significantly, leading to a much shorter MTTF and faster luminous flux depreciation. However, under the CCM, the junction temperatures of LEDs, MOSFETs, and diodes change modestly; therefore, the driver's MTTF and LED's luminous flux decay are not affected much by the variation of temperatures during LED's degradation process.Accepted author manuscriptElectronic Components, Technology and Material
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