Superconducting coils in AC application, such as in the stator of superconducting motors, have losses which warm up the coil and so limit the performance. Good thermal contact between the coil and the cooling agent is important. In this research we investigate the possibility of cooling the coils by a cryoliquid, such as liquid hydrogen or liquid nitrogen, flowing through capillaries in thermal contact with the coils. (C) 2017 Elsevier Ltd. All rights reserved.

We introduce the dune-curvilineargrid module. The module provides the self-contained, parallel grid manager, as well as the underlying elementary curvilinear geometry module dune-curvilineargeometry. This work is motivated by the need for reliable and scalable electromagnetic design of nanooptical devices. Curvilinear geometries improve both the accuracy of modeling smooth material boundaries, and the h/p-convergence rate of PDE solutions, reducing the necessary computational effort. dune-curvilineargrid provides a large spectrum of features for scalable parallel implementations of Finite Element and Boundary Integral methods over curvilinear tetrahedral geometries, including symbolic polynomial mappings and operations, recursive integration, sparse and dense grid communication, parallel timing and memory footprint diagnostics utilities. It is written in templated C++ using MPI for parallelization and ParMETIS for grid partitioning, and is provided as a module for the DUNE interface. The dune-curvilineargrid grid manager is continuously developed and improved, and so is this documentation. For the most recent version of the documentation, as well as the source code, please refer to the provided repositories and our website.

We introduce the electromagnetic eigenmodal solver code FemaxxNano for the numerical analysis of nanometer structured optical systems, a scientific field generally know as nanooptics. FemaxxNano solves the electric field vector wave equation and calculates the electromagnetic eigenmodes of nearly arbitrary 3-dimensional resonators, embedded either in free-space, vacuum or a background medium. Here, the study of the interaction between nanometer sized metallic structures and light is at the heart of the physical problem. Since metals in the optical region of the electromagnetic spectrum are highly dispersive and, thus, dissipative, dielectric media, we eventually obtain a nonlinear eigenvalue problem. We discretize the electromagnetic eigenvalue problem with the finite element method (FEM) in 3-dimensional space and on unstructured tetrahedral grids. We introduce a fully iterative scheme to solve the nonlinear problem for complex coefficient matrices that depend on wavelength. We investigate the properties of the algorithm in detail and demonstrate its performance by analyzing a nanometer sized optical dimer structure, a specific type of optical antenna, on distributed-memory parallel computers.

SUTOR is a project that is supported by the german ministry of economy and technology (FKZ 0327866A). The partners working on this project are Oswald Elektromotoren and Hochschule Aschaffenburg. Oswald is responsible for the layout of the Motor and its cryostat. Together with the Hochschule Aschaffenburg, Oswald has build a number of coils to determine the loss rates of superconductors when used with AC current and in external, oscillating magnetic fields. These results are taken to proof the at Oswald developed calculations for superconducting motors. The Hochschule Aschaffenburg is measuring the loss rates in superconducting coils and builds an inverter to fit the special requests a motor has when running with superconducting wires.The aim of this project is to realize a high torque motor that has compared to conventional torque motors a lower volume and weight, a higher efficiency and an increased dynamic acceleration.

We study a 3-dimensional, dual-field, fully explicit method for the solution of Maxwell's equations in the time domain on unstructured, tetrahedral grids. The algorithm uses the element level time domain (ELTD) discretization of the electric and magnetic vector wave equations. In particular, the suitability of the method for the numerical analysis of nanometer structured systems in the optical region of the electromagnetic spectrum is investigated. The details of the theory and its implementation as a computer code are introduced and its convergence behavior as well as conditions for stable time domain integration is examined. Here, we restrict ourselves to non-dispersive dielectric material properties since dielectric dispersion will be treated in a subsequent paper. Analytically solvable problems are analyzed in order to benchmark the method. Eventually, a dielectric microlens is considered to demonstrate the potential of the method. A flexible method of 2nd order accuracy is obtained that is applicable to a wide range of nano-optical configurations and can be a serious competitor to more conventional finite difference time domain schemes which operate only on hexahedral grids. The ELTD scheme can resolve geometries with a wide span of characteristic length scales and with the appropriate level of detail, using small tetrahedra where delicate, physically relevant details must be modeled.

In this article, the electromagnetic (EM) field in gap‐mode tip‐enhanced Raman spectroscopy (TERS) is investigated theoretically and experimentally for a range of commonly used and unusual metal and nonmetal substrates. By approaching a metal tip to a substrate, both form a coupled system that confines the EM field created at the tip apex. The influence of the substrate onto the EM field enhancement is observed in a top‐illumination gap‐mode TERS setup for different metal substrates. These include Au, the most commonly used substrate, and also a wide range of rarely or previously unused TERS substrates (Cu, Ag, Al, Pd, Pt, Ni, Ti, Mo, W, stainless steel, Al2O3, SiO2). Self‐assembled monolayers of thiols and brilliant cresyl blue thin film samples are investigated experimentally on nine metal substrates, all showing considerable TERS enhancement. With finite difference time domain and finite element simulations used, the article provides a good estimate of the EM field enhancement for a wide range of substrates for users to estimate how well a substrate of choice will perform in a gap‐mode TERS experiment. The reduction in EM field strength |E2| compared with Au is less than an order of magnitude for many metals (Calculations: Cu 92%, Ag 81%, Ni 53%). This article experimentally shows that a wide variety of conductive substrates can be used, when one is willing to trade a fraction of the EM field enhancement. TERS was seen on all metal substrates including stainless steel, yet quantification was not always possible. These qualitative results were complemented with intensities from calculations. The wider variety of substrates will increase the applicability of TERS and evolve it one step further towards use in standard analytics. Copyright © 2012 John Wiley & Sons, Ltd.

The transport AC losses (Qtr) of YBCO pancake coils wound from n = 1, 2, 4 non-transposed parallel connected (n-tpc) tapes have been investigated experimentally and theoretically. It was found that the Qtr AC losses of the coils with several n-tpc tapes consist of hysteresis AC losses (Qh) and coupling AC losses (Qcc). AC losses Qh of these coils are nearly the same as the AC losses of single-tape coils (n = 1). In contrast, Qcc are unique for coils with n > 1 n-tpc tapes. We found that the distribution of the coupling currents in the coil turns is defined by the magnetic flux penetrating between n-tpc tapes. This flux is related to the self-field component of the coil parallel to the tape surface, which is antisymmetrically distributed (an odd function) with respect to the winding center. This antisymmetrical distribution leads to a compensation effect of the coupling currents if n-tpc tapes are insulated along the turn length, in spite of low resistance between n-tpc tapes in the soldered coil ends. Therefore, AC losses Qcc of such coils are negligibly small compared to AC losses Qh. On the other hand, AC losses Qcc per current cycle are frequency dependent and have a maximum defined by the time constant τeff if tapes are non-insulated along the turn length. In this paper we estimated τeff for several special cases. In particular, we found that Qtr of YBCO pancake coils wound from several n-tpc tapes are comparable to Qtr of single-tape coils if the operating frequency f is far from the characteristic frequency 1/τeff.

We introduce a 3-dimensional electromagnetic eigenmodal algorithm for the theoretical analysis of resonating nano-optical structures. The method, a variant of the Jacobi-Davidson algorithm, solves the electric field vector wave, or curl-curl, equation for the electromagnetic eigenmodes of resonant optical structures with a finite element method. In particular, the method includes transparent boundary conditions that enable the analysis of resonating structures in unbounded space. We demonstrate the performance of the method. First, we calculate the modes of several dielectric resonator antennas and compare them to theoretically determined results. Second, we calculate the modes of a nano-cuboid and compare them to theoretically determined results. Third, we numerically analyze spherical nanoparticles and compare the result to the theoretical Mie solution. Fourth, we analyze optical dipole antenna configurations in order to assess the method's capability for solving technologically relevant problems.

The dyadic Green's function (DGF) method is an attractive approach for the calculation of electromagnetic scattering in spherically symmetric layered geometry. We investigate a recent formulation and reveal a problem that is associated with the nonconverging series that are employed for the calculation of the DGF in unbounded media. To overcome this deficiency, we introduce a new formulation that gives the desired solution analytically. The new technique combines operations on scalar Green's function with a rotation of the coordinate system. Our formulation also accelerates the algorithm to evaluate the DGF in spherically multilayered media. We present examples where we compare the conventional formulation with our new one.

Introduction: Ultrafine ambient particles are involved in pathogenesis of respiratory diseases. Particle surface area and adsorbed organic compounds including quinones may determine particle reactivity towards pulmonary target cells. We hypothesized that coating of UfCP with PQ (PQ-UfPC) changes reactivity towards alveolar macrophages (AM) compared to pristine particles. PQ-UfCP served as model for combustion-derived particles because PQ is a major quinone in diesel exhaust particles and atmospheric particulate matter. Viability, phagocytosis, respiratory burst activity, formation of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) and the integrity of the actin filament were studied. These parameters were chosen to evaluate the functionality of AM treated with these particles.

The new generation X-ray Free Electron Laser (SwissFEL) under development at the Paul Scherrer Institut (PSI) will employ a transverse deflecting cavity [3] for beam diagnostics. Since this cavity design breaks the symmetry, a complete 3-dimensional eigenmodal analysis is indispensable. The 3-dimensional eigenmodal solver Femaxx has been developed in a collaboration between PSI and the Swiss Federal Institute of Technology (ETH) Zurich. Femaxx [2] aims at large-size generalized eigenvalue problems, therefore it has been optimized for distributed memory parallel compute clusters. We use Femaxx to analyze the transverse deflecting cavity, i.e., to compute electromagnetic eigenmodes corresponding to the lower eigenfrequencies. For further usage in the beam dynamics code OPAL [1], we sample the eigenmodal fields on a 3dimensional Cartesian grid. DESCRIPTION OF THE PROBLEM The Femaxx code solves the Vector Wave Equation: Let Ω be a closed domain describing a large accelerator structure. Neither do we assume that external fields, sources or charges are present, nor do we consider loss mechanisms. The perfect boundary condition applies on the surface Γ of the domain. Then the electromagnetic eigenmodes and eigenfrequencies can be computed by solving the eigenvalue problem. curl curl E(x) = λE(x), x ∈ Ω, λ = ω/c, (1) divE(x) = 0, x ∈ Ω (2) n ×E(x) = 0, x ∈ Γ (3) (2) imposes the divergence-free constraint in the sourcefree domain, and (3) is the infinite conductivity boundary condition on the surface. The magnetic field H is then calculated by the relation. H(x) = 1 −iωμ0 curlE(x) (4)

The concept of antennas has found renewed interest in near-field optics and the optics of nanometer-structured systems where dimensions are significantly smaller than the wavelength A. Optical antennas usually consist of a combination of dielectric and metallic materials. Similar concepts are increasingly studied for nanometer-structured field-emission cathodes and field emitter arrays (FEA). They are used for time-resolved electron interferometry, imaging and for sources in particle accelerators where both single-tip emitters and FEA are currently studied. In this study we implement a finite element time domain (FETD) algorithm for the calculation of the electric field involving metals in the visible range of the electromagnetic spectrum, using a dispersive Drude dielectric model. We compute the distribution of the electric field for an optical antenna setup, consisting of a sharpened dielectric fiber tip and an attached gold nano-particle of sub-wavelength size, excited by an incoming plane wave from the negative z-axis that impinges onto the gold nanoparticle. We demonstrate the existence of spots of light of sub-wavelength dimensions, instrumental for circumventing the diffraction limit, i.e., to be able to detect objects smaller than about half the wavelength. We also model the coupling of the incoming plane wave into the dielectric fiber tip via the gold nano-particle. Finally, we demonstrate the importance of the finite element approach. Due to its inherent level of detail (LoD) it allows for the efficient discretization of configurations with a wide span of scales, from nanometer to micrometer, and, equally important, for the conformal and therefore more accurate discretization of curved geometrical features.

We present for the first time the use of contrast-enhanced multislice computed tomography in trauma care to detect acute myocardial infarction and verify it as the cause of a traffic accident. In addition to the case report, cardiac contusion, coronary dissection, and facets of insurance law are discussed. The determination of acute myocardial infarction, cardiac contusion, and coronary dissection can be challenging, but answers can be found in the medical history and accident details. The trauma surgeon in the emergency department must always be interested in clarifying the cause of trauma and keeping a secondary diagnosis in mind to strive for the goal of optimal and complete polytrauma care.

Unser Fall zeigt erstmals die Diagnostik eines akuten Myokardinfarkts als Unfallursache in der Polytrauma-Computertomographie im Rahmen des Schockraummanagements. Dabei stellt die Kontrastmittel (KM)-CT das wichtigste Instrumentarium zur Diagnosefindung dar. Neben dem Fallbericht werden die Differenzialdiagnosen wie die Herzkontusion, die direkte Verletzung oder Dissektion der Koronararterien und der versicherungsrechtliche Aspekt der Klärung des Myokardinfarkts als Unfallursache beschrieben. In unserem Fall war die Demarkierung der Hinterwand in der KM-CT für die Diagnosefindung des Myokardinfarkts als Unfallursache wegweisend. Trotzdem ist die Abgrenzung zwischen Myokardinfarkt als Ursache oder Folge eines Unfalls schwierig. Gemeinsam mit der Lokalisation der Verletzung haben hier die Anamnese und der Unfallmechanismus Schlüsselfunktionen. Nur in der Zusammenschau kann der primäre Myokardinfarkt im Rahmen der Polytraumaversorgung frühzeitig diagnostiziert und von anderen Differenzialdiagnosen abgegrenzt werden.

Considerable effort has been invested into numerical models of scanning near-field optical microscopy during the last years. The finite difference time domain method, using an orthogonal discretization scheme, has often been used for full-wave three-dimensional studies. Because optical near-field configurations are often characterized by curvilinear shapes, locally refined, tetrahedral grids are better suited to describe the geometry. Where fine geometrical details must be resolved or the field solution is expected to vary rapidly, the elements are made smaller while in the other regions a coarser mesh can be used, thereby reducing the size of the problem and promoting computational efficiency. In this study, we use a finite element approach that solves the electric field vector wave (curl–curl) equation in the time domain (FETD) to investigate a novel, scanning near-field optical probe concept with asymmetric cladding. A specific advantage of the finite element method is its inherent capability to discretize the curl–curl equation in a non-uniform way. The finite element method is therefore particularly suited to approximate the geometry of an optical near-field configuration. We model a simplified setup, introduce specific approximations and discuss the method’s capabilities and its potential for modeling more complex configurations.

Significant problems facing all experimental and computational sciences arise from growing data size and complexity. Common to all these problems is the need to perform efficient data I/O on diverse computer architectures. In our scientific application, the largest parallel particle simulations generate vast quantities of six-dimensional data. Such a simulation run produces data for an aggregate data size up to several TB per run. Motived by the need to address data I/O and access challenges, we have implemented H5Part, an open source data I/O API that simplifies the use of the Hierarchical Data Format v5 library (HDF5). HDF5 is an industry standard for high performance, cross- platform data storage and retrieval that runs on all contemporary architectures from large parallel supercomputers to laptops. H5Part, which is oriented to the needs of the particle physics and cosmology communities, provides support for parallel storage and retrieval of particles, structured and in the future unstructured meshes. In this paper, we describe recent work focusing on I/O support for particles and structured meshes and provide data showing performance on modern supercomputer architectures like the IBM POWER 5.

The present work illustrates that enantiopure BINOL-derived diphosphoramidite ligands with hydrazine spacers are good ligands for the rhodium-catalyzed hydrogenation of 2-acetylamino-3-arylpropenoic methyl esters. The substituents on the two hydrazine nitrogens have a large influence on the enantioselectivity of the reaction, with bulky symmetrical groups leading to the highest ee values.

The present state of development of highly dynamic motors to be operated at 77 K (one HTS Linear Motor with superconducting double pancake stator windings and one four pole rotating synchronous motor with REM in the rotor, REM = rear earth magnets) is described. The final design of both machines is presented. The performance of BSCCO double pancake coils (dc, ac, and losses) is reported. Special considerations have been made with respect to cooling of the HTS tapes and cryogenic stability.

The PSI XFEL project aims at developing a pulsed high- brightness, high-current electron source which is one of the prerequisites of a cost-effective high-power laser-like X- ray light source. Creating an ultra low emittance beam is a great challenge, transporting, i.e., accelerating and compressing it is equally difficult. We present a 3D start-to-end simulation of our planned 250 MeV injector facility. The injector consists of a photocathode with pulsed DC acceleration followed by a two-cell standing-wave L-band cavity that leads into a ballistic bunching section. After some further velocity bunching in an L-band structure the electron beam enters several S-band structures which accelerate it up to the final energy of 250 MeV. An X-band RF structure prepares the beam for the following bunch compressor in which the target peak current of 350 A is reached. The target value of the slice emittance is 0.1 mm mrad, necessitating precise beam dynamics simulations. For the 3D simulations we use IMPACT-T, a time domain parallel particle tracking code, in which the self fields are treated in the electrostatic approximation. We discuss various issues such as projected and slice emittance preservation and shed light on some of the differences between an envelope and the 3D model.