Loss comparison of 2 and 3-level inverter topologies

This paper investigates semiconductor and DC-link capacitor losses in two two-level and two three-level voltage source inverters. The components of the four inverters are selected to have appropriate voltage and current ratings. Analytical expressions for semiconductor losses are reviewed and expressions for DC link capacitor losses are derived for all topologies. Three-level inverters are found to have lower semiconductor losses, but higher DC-link capacitor losses. Overall, the three-level Neutral-Point-Clamped inverter proved to be the most efficient topology

Analysis of DC-Link capacitor losses in three-level neutral point clamped and cascaded H-Bridge voltage source inverters

Loss estimation is a critical aspect of inverter design.The present work investigates the losses occurring in the DC-link capacitors of the three-phase three-level neutral point clamped and cascaded H-Bridge inverter topologies, by performing a harmonic analysis of the capacitor currents.Results are verified by simulations. Their analysis reveals the advantage of the NPC inverter

Description of risk assesment analysis methods and application at the hospital laboratory proccesses.

180 σ.Στην εργασία που εκπονήθηκε παρατίθενται οι βασικές έννοιες και μέθοδοι που χρησιμοποιούνται για την ανάλυση συστημάτων και την προληπτική διαχείριση κινδύνων σε ένα υπό σχεδίαση ή υπό λειτουργία σύστημα ή μέσο εργασίας. Η έρευνα που ζητείται να γίνει σε αυτή τη διπλωματική εργασία, με βάση τη μέθοδο Ανάλυσης Καταστάσεων και Επιπτώσεων Αστοχίας (FMEA), αφορά ένα τριτοβάθμιο παιδιατρικό νοσοκομείο. Η ανάλυση συνίσταται στη σαφή και λεπτομερή αποτύπωση της διαδικασίας­ροής της πληροφορίας (στοιχείων ασθενή, εξετάσεων καιαποτελεσμάτων) και του δείγματος του ασθενή στο βιοχημικό εργαστήριο, που αποτελούν και τον έλεγχο ποιότητας, σε συνδυασμό και με την ανάλυση της ευαισθησίας του συστήματος σε ενδεχόμενα λάθη (ανάλυση επικινδυνότητας και βελτιωτικά μέτρα). Στόχος είναι ο σχεδιασμός των εργαστηριακών διαδικασιών, όπως και οι δικλείδες ασφαλείας που θα εμπεριέχουν για την αποφυγή λαθών, να είναι τέτοια, ώστε η ποιότητα της πληροφορίας που θα λάβει ο γιατρός ή η ομάδα γιατρών να θεωρείται κατάλληλη για να γίνει η σωστή διάγνωση για τον ασθενή.In the final thesis there are listed and described the basic significances and methods used for the analysis of the systems and for the risk proactive management, in a under designing or under operation system or means of work. The Failure Modes and Effects Analysis (FMEA) applied on a research performed in a tertiary pediatric hospital. The analysis consists in the explicit and detailed imprinting of the process­flow of the information (patient data, examinations and results)and of the patient samples in the biochemical laboratory, which constitutes also the quality control, in combination with the system sensitivity analysis in potential errors (hazard analysis and improvement measures). The objective is the design of the laboratorial procedures, as well as the safeguards included for the rejection of errors, to be such, so the quality of information received by the doctor or team of doctors is considered appropriate in order to make the right diagnosis for the patient.Ιωάννης Γ. Οργανουδάκη

Hybrid modulation strategies for eliminating low-frequency neutral-point voltage oscillations in the neutral-point-clamped converter

Nearest vector (NV) modulation strategies for the neutral-point-clamped converter are known to generate low-frequency neutral point (NP) voltage oscillations. Non-NV strategies can eliminate these oscillations, but at the expense of higher switching losses and output voltage harmonic distortion. This letter proposes a simple way of creating hybrid strategies, as combinations of NV and non-NV strategies, which are also able to eliminate NP voltage oscillations. The approach minimizes the participation of non-NV strategies and hence their drawbacks, while it can be applied to any type of load (nonlinear and/or unbalanced). Simulations in MATLAB-Simulink are used to illustrate its operation.<br/

Defining the minimal interacting regions of the tight junction protein MAGI-1 and HPV16 E6 oncoprotein for solution structure studies

The oncoprotein E6 produced by tumorigenic high-risk genital human papillomaviruses targets a number of cellular proteins containing PDZ domains for proteasome-mediated degradation. In particular, E6 targets the tight junction protein MAGI-1 by binding to its PDZ1 domain. Using light scattering and NMR, we explored different fragments of both the HPV16 E6 and the MAGI-1 PDZ1 domain to define the best-behaving complex for solution structure studies. We showed that the 70-residue HPV16 E6 C-terminal domain (E6C) can be efficiently substituted by a peptide spanning the 11 C-terminal residues of E6. The construct of MAGI-1 PDZ1 best suited for solution structure analysis presents a 14-residue N-terminal extension and a 26-residue C-terminal extension as compared to the construct used for the recently solved X-ray structure of a MAGI-1 PDZ1/HPV18 E6 complex. These data suggest a stabilizing role for the interdomain linker regions which separate the PDZ1 domain from its neighboring domains

Identification using phage display of peptides promoting targeting and internalization into HPV-transformed cell lines.

'High-risk' human papilloma viruses (HPVs) cause cervical tumours. In order to treat these tumours therapeutic approaches must be developed that efficiently target the tumour cells. Using phage display, we selected tumour-targeting peptides from a library of constrained nonamer peptides presented multivalently on pVIII of M13. Three different consensus peptide sequences were isolated by biopanning on HPV16-transformed SiHa cells. The corresponding phage-peptides targeted and were internalized in HPV16 transformed SiHa and CaSki cells as well as in HPV18-transformed HeLa cells, but failed to bind a panel of normal or transformed cell lines. Two of the three selected peptides targeted cells only when presented on phage particles in a constrained conformation. However, all three peptides retained their targeting capacity when presented on the reporter protein enhanced green fluorescent protein (EGFP) in a monovalent form. These peptides may be useful for the design of drug or gene delivery vectors for the treatment of cervical cancer