Structure Function Measurements at the LHC

Since the current uncertainty on the structure of the proton affects the new physics discovery potential of LHC, the ATLAS collaboration is investigating methods to constrain this uncertainty over the whole LHC kinematic regime. The Standard Model processes such as direct photon, Z, W and inclusive jet productions are optimal candidates for this purpose.Comment: 4 pages, 4 figures, to appear in the proceedings of the PHOTON2005 Conferenc

Reciprocity relation for the vector radiative transport equation and its application to diffuse optical tomography with polarized light

We derive a reciprocity relation for vector radiative transport equation (vRTE) that describes propagation of polarized light in multiple-scattering media. We then show how this result, together with translational invariance of a plane-parallel sample, can be used to compute efficiently the sensitivity kernel of diffuse optical tomography (DOT) by Monte Carlo simulations. Numerical examples of polarization-selective sensitivity kernels thus computed are given.Comment: 5 pages, 3 figure

Parton Densities at the LHC

This contribution to the Italian "Workshop sui Monte Carlo, la Fisica e le Simulazioni a LHC", held at LNF, Frascati, in February, May and October 2006, summarises the status of parton density functions (PDF's) and the impact of their uncertainties on the LHC physics. Emphasis is given to methods of contraining PDF's using LHC data. Moreover, the advantages of the so-called PDF reweighting technique, which enables to quickly estimate PDF uncertainties with Monte Carlo events, are also presented.Comment: 9 pages, 5 figures, to appear in the proceedings of the Italian "Workshop sui Monte Carlo, la Fisica e le Simulazioni a LHC", LNF, Frascati, 200

Enhancement of reliability in condition monitoring techniques in wind turbines

The majority of electrical failures in wind turbines occur in the semiconductor components (IGBTs) of converters. To increase reliability and decrease the maintenance costs associated with this component, several health-monitoring methods have been proposed in the literature. Many laboratory-based tests have been conducted to detect the failure mechanisms of the IGBT in their early stages through monitoring the variations of thermo-sensitive electrical parameters. The methods are generally proposed and validated with a single-phase converter with an air-cored inductive or resistive load. However, limited work has been carried out considering limitations associated with measurement and processing of these parameters in a three-phase converter. Furthermore, looking at just variations of the module junction temperature will most likely lead to unreliable health monitoring as different failure mechanisms have their own individual effects on temperature variations of some, or all, of the electrical parameters. A reliable health monitoring system is necessary to determine whether the temperature variations are due to the presence of a premature failure or from normal converter operation. To address this issue, a temperature measurement approach should be independent from the failure mechanisms. In this paper, temperature is estimated by monitoring an electrical parameter particularly affected by different failure types. Early bond wire lift-off is detected by another electrical parameter that is sensitive to the progress of the failure. Considering two separate electrical parameters, one for estimation of temperature (switching off time) and another to detect the premature bond wire lift-off (collector emitter on-state voltage) enhance the reliability of an IGBT could increase the accuracy of the temperature estimation as well as premature failure detection

CHARACTERIZATION OF BRANCHED HISTIDINE-LYSINE POLYPEPTIDES USED FOR NUCLEIC ACID DELIVERY AND THEIR COMPLEXES WITH DNA AND SMALL INTERFERING RNA.

DNA and siRNA must be packaged for protection prior to transfection in vivo when they are administered to humans or other animals. Dr. A. J. Mixson's laboratory at the University of Maryland, Baltimore Medical School has developed a family of branched histidine-lysine (HK) peptides that confer improved transfection in mice compared to naked nucleic acid. The branched polymer denoted H3K4b has a superior ability to transfect siRNA in vitro compared to H3K(+G)4b. H3K(+G)4b, made by the addition of two glycines to each of the original H3K4b branches, is presumably a more flexible polymer, and it allows for better transfection of plasmid DNA than H3K4b. Biophysical characterization of the HK-DNA and HK-siRNA complexes is aimed at understanding how the structures of both peptides affect their biological activity. This characterization was performed using ethidium bromide exclusion from nucleic acid, DNase I plasmid degradation, dynamic light scattering, circular dichroism, isothermal titration calorimetry and atomic force microscopy. Results from the characterization suggest that H3K4b forms condensed regions of packaged plasmid with some repeating accessibility of the DNA, compared to a more even coating of plasmid by H3K(+G)4b. Based on these results a "coating versus clumping" model was developed to relate the transfection efficiency of each peptide to its binding of plasmid DNA. A specific model for packaging of siRNA with these peptides was not developed, but we believe that characteristics that lead to effective transfection of plasmid are not key to siRNA delivery. A better understanding of characteristics important to peptide-nucleic acid complex formation may lead to the development of improved transfection agents

Power Electronic Autotransformer Based 3×25 kV Network for Power Quality Enhancement In Railway Supply Systems

State of the art single-phase AC traction systems are based on a split-phase 2×25kV supply network with multiple regularly spaced auto-transformers. The main drawbacks of this arrangement are the unbalanced currents in the three-phase grid and reactive power flow due to transformers and auto-transformers. This paper proposes to solve these issues with a completely new 3×25 kV railway power supply supported by a power electronic autotransformer (PEAT). The PEAT circuit comprises of single-phase back-to-back voltage source converters, connected across different phase pairs of the three-phase network. These voltage-source converters balance the three-phase grid current for all traction load conditions, ensuring grid compliant power quality performance. Over and above that, the PEAT system enables reactive power control and ensure unity power factor at the point of connection. Besides detailing the control algorithm for the PEAT system, this paper also discusses various design aspects and optimal positioning of the PEAT unit along the railway line. The efficacy of the PEAT topology is illustrated through extensive simulations carried out in Matlab/Simulink environment. These are further validated via real time hardware-in-the-loop (HIL) results obtained from a Typhoon HIL 404 device together with a C2000 microcontroller based interface card

Metro Trains Equipped Onboard withSupercapacitors: a Control Technique forEnergy Saving

The paper deals with the use of onboard supercapacitors for metro trains. The practical utilization of supercapacitors requires suitable power converters for the regulation of power flows between the catenary and the electrical drives of the power-train. These converters operate in dc current and have to be bi-directional in order to allow the charge and discharge of supercapacitors. The mathematical model of the whole electrical drive has been developed and the main features of the control strategy have been presented. The control is capable of limiting the peak currents of the contact line and recovering partially the kinetic energy of the train during the braking periods. Simulations prove that the suggested control strategy is very effective for both purposes. Experimental tests made on a scaled prototype, representing the translating masses of a train, fully confirm the results of the simulations