798 research outputs found

    Hysteresis Bearingless Slice Motors with Homopolar Flux-biasing

    Get PDF
    We present a new concept of bearingless slice motor that levitates and rotates a ring-shaped solid rotor. The rotor is made of a semi-hard magnetic material exhibiting magnetic hysteresis, such as D2 steel. The rotor is radially biased with a homopolar permanent-magnetic flux, on which the stator can superimpose two-pole flux to generate suspension forces. By regulating the suspension forces based on position feedback, the two radial rotor degrees of freedom are actively stabilized. The two tilting degrees of freedom and the axial translation are passively stable due to the reluctance forces from the bias flux. In addition, the stator can generate a torque by superimposing six-pole rotating flux, which drags the rotor via hysteresis coupling. This six-pole flux does not generate radial forces in conjunction with the homopolar flux or two-pole flux, and therefore the suspension force generation is in principle decoupled from the driving torque generation. We have developed a prototype system as a proof of concept. The stator has 12 teeth, each of which has a single-phase winding that is individually driven by a linear transconductance power amplifier. The system has four reflectivetype optical sensors to differentially measure the two radial degrees of freedom of the rotor. The suspension control loop is implemented such that the phase margin is 25° at the cross-over frequency of 110 Hz. The prototype system can levitate the rotor and drive it up to about 1730 r/min. The maximum driving torque is about 2.7 mNm

    Lebensraum Adria zwischen 1355 und 1456

    Get PDF
    Der Lebensraum Adria in den Jahren 1355 bis 1456 steht im Mittelpunkt dieser Diplomarbeit, deren Intention es ist, sowohl Ereignis- als auch Sozial-, MentalitĂ€ts- Umwelt- und Wirtschaftsgeschichte zu behandeln. Im Laufe der Arbeit musste jedoch dieser Adriaraum mehrfach modifiziert werden, da es nicht möglich war, einen klar erfassbaren gemeinsamen Raum herauszuarbeiten. Letztlich wurde ein Schalenmodell konstruiert, bei dem die verschiedenen Schalen immer mehr Gemeinsamkeiten aufwiesen, je weiter man in das Innere der Schichten vordrang. Der innere und der Ă€ußere Adriaraum sind die Grobeinteilung dieses Adriaraums und die Grenzen zwischen ihnen, die vor allem durch die Geographie vorgegeben wurden, verliefen relativ starr. Die Trennlinien zwischen Ă€ußerem Adriaraum und Nicht-Adriaraum hatten dagegen Grenzsaumcharakter und waren, sowohl sehr breit, als auch fließend

    Deep Infiltrating Endometriosis and Adenomyosis: Implications on Pregnancy and Outcome

    Get PDF
    Endometriosis (EM), especially deep infiltrating endometriosis (DIE) and adenomyosis (AM), are known to cause pain and sterility in young women. More recently, they have also been described as risk factors for obstetric complications. While the pathophysiology is not yet completely understood, they seem to share a common origin: archimetrosis. Methods: A systematic literature review was conducted to summarize the existing evidence on DIE and AM as risk factors for obstetric complications. Results: Preterm birth, caesarean section delivery (CS) and placental abnormalities are associated with the diagnosis of DIE and AM. Women with AM seem to experience more often hypertensive pregnancy disorders, premature rupture of membranes and their children are born with lower birth weights than in the control groups. However, many of the studies tried to evaluate AM, EM and DIE as separate risk factors. Moreover, often they did not adjust for important confounders such as multiple pregnancies, parity, mode of conception and maternal age. Therefore, prospective studies with larger numbers of cases and appropriate adjustment for confounders are needed to explore the pathophysiology and to prove causality

    Light-cone distribution amplitudes of the baryon octet

    Get PDF
    We present results of the first ab initio lattice QCD calculation of the normalization constants and first moments of the leading twist distribution amplitudes of the full baryon octet, corresponding to the small transverse distance limit of the associated S-wave light-cone wave functions. The P-wave (higher twist) normalization constants are evaluated as well. The calculation is done using Nf=2+1N_f=2+1 flavors of dynamical (clover) fermions on lattices of different volumes and pion masses down to 222 MeV. Significant SU(3) flavor symmetry violation effects in the shape of the distribution amplitudes are observed.Comment: Update to the version published in JHE

    Light-cone distribution amplitudes of octet baryons from lattice QCD

    Full text link
    We present lattice QCD results for the wave function normalization constants and the first moments of the distribution amplitudes for the lowest-lying baryon octet. The analysis is based on a large number of Nf=2+1N_f=2+1 ensembles comprising multiple trajectories in the quark mass plane including physical pion (and kaon) masses, large volumes, and, most importantly, five different lattice spacings down to a=0.039 fma=0.039\,\mathrm{fm}. This allows us to perform a controlled extrapolation to the continuum and infinite volume limits by a simultaneous fit to all available data. We demonstrate that the formerly observed violation of flavor symmetry breaking constraints can, indeed, be attributed to discretization effects that vanish in the continuum limit

    Thiol-gelatin-norbornene bioink for laser‐based high‐definition bioprinting

    Get PDF
    Two-photon polymerization (2PP) is a lithography-based 3D printing method allowing the fabrication of 3D structures with sub-micrometer resolution. This work focuses on the characterization of gelatin-norbornene (Gel-NB) bioinks which enables the embedding of cells via 2PP. The high reactivity of the thiol-ene system allows 2PP processing of cell-containing materials at remarkably high scanning speeds (1000 mm s(-1)) placing this technology in the domain of bioprinting. Atomic force microscopy results demonstrate that the indentation moduli of the produced hydrogel constructs can be adjusted in the 0.2-0.7 kPa range by controlling the 2PP processing parameters. Using this approach gradient 3D constructs are produced and the morphology of the embedded cells is observed in the course of 3 weeks. Furthermore, it is possible to tune the enzymatic degradation of the crosslinked bioink by varying the applied laser power. The 3D printed Gel-NB hydrogel constructs show exceptional biocompatibility, supported cell adhesion, and migration. Furthermore, cells maintain their proliferation capacity demonstrated by Ki-67 immunostaining. Moreover, the results demonstrate that direct embedding of cells provides uniform distribution and high cell loading independently of the pore size of the scaffold. The investigated photosensitive bioink enables high-definition bioprinting of well-defined constructs for long-term cell culture studies
    • 

    corecore