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See detailOff-line Correlator for Antenna Array Over Long Baselines
Ardito, Alessandro; Abelllo, Ricard; Aroumont, Anbazhagan et al

in 2019 8th International Workshop on Tracking, Telemetry and Command Systems for Space Applications (TTC) (2019)

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See detailPhysical layer security over fading wiretap channels through classic coded transmissions with finite block length and discrete modulation
Baldi, Marco; Maturo, Nicola UL; Ricciutelli, Giacomo et al

in Physical Communication (2019)

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See detailA Coordinate Descent Framework to Joint Design of MPSK Sequences and Receive Filter Weights in MIMO Radar Systems
Alaee-Kerahroodi, Mohammad UL

in 2019 IEEE Radar Conference (RadarConf) (2019)

In this paper, we aim at a joint design of M-ary Phase Shift Keying (PSK) - or MPSK - transmit waveform and receive space-time filter to maximize the Signal to Interference plus Noise Ratio (SINR) in ... [more ▼]

In this paper, we aim at a joint design of M-ary Phase Shift Keying (PSK) - or MPSK - transmit waveform and receive space-time filter to maximize the Signal to Interference plus Noise Ratio (SINR) in colocated Multiple Input Multiple Output (MIMO) radar systems. The design problem is formulated into a maximization of the SINR, including unimodular discrete phase constraint on the transmit waveforms. The resulting problem is non-convex, whereby we devise an iterative algorithm based on the Coordinate Descent (CD) framework to tackle it iteratively. To reduce the computational complexity in designing the transmit waveforms, we exploit the properties of Fast Fourier Transform (FFT) in this paper. Numerical examples illustrate the superior performance of the proposed algorithm in comparison with the state-of-the-art counterparts. [less ▲]

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See detailTheoretical Analysis and Implementation of Effective Receivers for Telecommand Space Links
Baldi, Marco; Bertinelli, Massimo; Chiaraluce, Franco et al

in 2019 8th International Workshop on Tracking, Telemetry and Command Systems for Space Applications (TTC) (2019)

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See detailDesigning Sets of Binary Sequences for MIMO Radar Systems
Alaee-Kerahroodi, Mohammad UL; Modarres-Hashemi, Mahmoud; Naghsh, Mohammad Mahdi

in IEEE Transactions on Signal Processing (2019), 67(13), 3347--3360

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See detailDesigning (In) finite-alphabet Sequences via Shaping the Radar Ambiguity Function
Alaee-Kerahroodi, Mohammad UL; Sedighi, Saeid UL; MR, Bhavani Shankar et al

in ICASSP 2019-2019 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) (2019)

In this paper, a new framework for designing the radar transmit waveform is established through shaping the radar Ambiguity Function (AF). Specifically, the AF of the phase coded waveforms are analyzed ... [more ▼]

In this paper, a new framework for designing the radar transmit waveform is established through shaping the radar Ambiguity Function (AF). Specifically, the AF of the phase coded waveforms are analyzed and it is shown that a continuous/discrete phase sequence with the desired AF can be obtained by solving an optimization problem promoting equality between the AF of the transmit sequence and the desired AF. An iterative algorithm based on Coordinate Descent (CD) method is introduced to deal with the resulting non-convex optimization problem. Numerical results illustrate the proposed algorithm make it possible to design sequences with remarkably high tolerance towards Doppler frequency shifts, which is of interest to the future generations of automotive radar sensors. [less ▲]

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See detailThe independence of the disciplinary chamber of the Polish Supreme Court or how to forget about discipline
Zinonos, Panagiotis UL

Diverse speeches and writings (2019)

Case brief and comments on the joint cases concerning the independence of the disciplinary chamber of the Polish Supreme Court (C-585/18, C-624/18 & C-625/18)

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See detailAligning self-assembled perylene bisimides in a magnetic field.
Draper, Emily R.; Wallace, Matthew; Honecker, Dirk UL et al

in Chemical communications (Cambridge, England) (2018), 54(78), 10977-10980

Photoconductive self-assembled 1D structures can be formed by perylene bisimides. These structures are generally randomly orientated, limiting their applications as conductive wires. Here, we show that ... [more ▼]

Photoconductive self-assembled 1D structures can be formed by perylene bisimides. These structures are generally randomly orientated, limiting their applications as conductive wires. Here, we show that magnetic fields can be used to create highly aligned, directionally-dependent thin films. This approach leads to well-aligned structures over large areas. [less ▲]

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See detailDirect evidence for cycloidal modulations in the thermal-fluctuation-stabilized spin spiral and skyrmion states of GaV4S8
White, J. S.; Butykai, A.; Cubitt, R. et al

in PHYSICAL REVIEW B (2018), 97(2),

We report small-angle neutron scattering studies of the lacunar spinelGaV4S8,which reveal the long-wavelength magnetic phases to be cycloidally modulated. Upon cooling, these modulated phases, including a ... [more ▼]

We report small-angle neutron scattering studies of the lacunar spinelGaV4S8,which reveal the long-wavelength magnetic phases to be cycloidally modulated. Upon cooling, these modulated phases, including a recently proposed Néel-type skyrmion phase, transform into a simple ferromagnetic state. These results indicate the modulated phases in GaV4S8 gain their stability from thermal fluctuations, while at lower temperatures the ferromagnetic state emerges in accord with the strong easy-axis magnetic anisotropy. Crucially, our study provides microscopic evidence that the skyrmions in GaV4S8 indeed display a Néel-type helicity. More generally, our approach can be applied to evidence the helicity of any bulk skyrmion phase. [less ▲]

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See detailTransparent-to-dark photo- and electrochromic gels
Gonzalez, Laura; Liu, Chung; Dietrich, Bart et al

in COMMUNICATIONS CHEMISTRY (2018), 1

Smart windows in which the transmittance can be controlled on demand are a promising solution for the reduction of energy use in buildings. Windows are often the most energy inefficient part of a building ... [more ▼]

Smart windows in which the transmittance can be controlled on demand are a promising solution for the reduction of energy use in buildings. Windows are often the most energy inefficient part of a building, and so controlling the transmittance has the potential to significantly improve heating costs. Whilst numerous approaches exist, many suitable materials are costly to manufacture and process and so new materials could have a significant impact. Here we describe a gel-based device which is both photo- and electrochromic. The gel matrix is formed by the self-assembly of a naphthalene diimide. The radical anion of the naphthalene diimide can be formed photo or electrochemically, and leads to a desirable transition from transparent to black. The speed of response, low potential needed to generate the radical anion, cyclability of the system, temperature stability and low cost mean these devices may be suitable for applications in smart windows. [less ▲]

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See detailRelating Magnetic Properties and High Hyperthermia Performance of Iron Oxide Nanoflowers
Bender, Philipp Florian UL; Fock, Jeppe; Frandsen, Cathrine et al

in JOURNAL OF PHYSICAL CHEMISTRY C (2018), 122(5), 3068-3077

We investigated, in depth, the interrelations among structure, magnetic properties, relaxation dynamics and magnetic hyperthermia performance of magnetic nanoflowers. The nanoflowers are about 39 nm in ... [more ▼]

We investigated, in depth, the interrelations among structure, magnetic properties, relaxation dynamics and magnetic hyperthermia performance of magnetic nanoflowers. The nanoflowers are about 39 nm in size, and consist of densely packed iron oxide cores. They display a remanent magnetization, which we explain by the exchange coupling between the cores, but we observe indications for internal spin disorder. By polarized small-angle neutron scattering, we unambiguously confirm that, on average, the nanoflowers are preferentially magnetized along one direction. The extracted discrete relaxation time distribution of the colloidally dispersed particles indicates the presence of three distinct relaxation contributions. We can explain the two slower processes by Brownian and classical Néel relaxation, respectively. The additionally observed very fast relaxation contributions are attributed by us to the relaxation of disordered spins within the nanoflowers. Finally, we show that the intrinsic loss power (ILP, magnetic hyperthermia performance) of the nanoflowers measured in colloidal dispersion at high frequency is comparatively large and independent of the viscosity of the surrounding medium. This concurs with our assumption that the observed relaxation in the high frequency range is primarily a result of internal spin relaxation, and possibly connected to the disordered spins within the individual nanoflowers. [less ▲]

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See detailDirect evidence for cycloidal modulations in the thermal-fluctuation-stabilized spin spiral and skyrmion states of GaV 4 S 8
White, J. S.; Butykai, A.; Cubitt, R. et al

in Physical Review B (2018), 97(2), 020401

We report small-angle neutron scattering studies of the lacunar spinelGaV4S8,which reveal the long-wavelength magnetic phases to be cycloidally modulated. Upon cooling, these modulated phases, including a ... [more ▼]

We report small-angle neutron scattering studies of the lacunar spinelGaV4S8,which reveal the long-wavelength magnetic phases to be cycloidally modulated. Upon cooling, these modulated phases, including a recently proposed Néel-type skyrmion phase, transform into a simple ferromagnetic state. These results indicate the modulated phases in GaV4S8 gain their stability from thermal fluctuations, while at lower temperatures the ferromagnetic state emerges in accord with the strong easy-axis magnetic anisotropy. Crucially, our study provides microscopic evidence that the skyrmions in GaV4S8 indeed display a Néel-type helicity. More generally, our approach can be applied to evidence the helicity of any bulk skyrmion phase. [less ▲]

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See detailMultiple-q noncollinear magnetism in an itinerant hexagonal magnet
Takagi, R.; White, J. S.; Hayami, S. et al

in SCIENCE ADVANCES (2018), 4(11),

rticle Figures & Data Info & Metrics eLetters PDF Abstract Multiple-q spin order, i.e., a spin texture characterized by a multiple number of coexisting magnetic modulation vectors q, has recently ... [more ▼]

rticle Figures & Data Info & Metrics eLetters PDF Abstract Multiple-q spin order, i.e., a spin texture characterized by a multiple number of coexisting magnetic modulation vectors q, has recently attracted attention as a source of nontrivial magnetic topology and associated emergent phenomena. One typical example is the triple-q skyrmion lattice state stabilized by Dzyaloshinskii-Moriya interactions in noncentrosymmetric magnets, while the emergence of various multiple-q states of different origins is expected according to the latest theories. Here, we investigated the magnetic structure of the itinerant polar hexagonal magnet Y3Co8Sn4, in which several distinctive mechanisms favoring multiple-q states are allowed to become active. Small-angle neutron-scattering experiments suggest the formation of incommensurate triple-q magnetic order with an in-plane vortex-like spin texture, which can be most consistently explained in terms of the novel four-spin interaction mechanism inherent to itinerant magnets. The present results suggest a new route to realizing exotic multiple-q orders and that itinerant hexagonal magnets, including the R3M8Sn4 family with wide chemical tunability, can be a unique material platform to explore their rich phase diagrams. [less ▲]

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See detailNoncollinear magnetism in nanosized cobalt chromite
Zakutna, D.; Vlcek, J.; Fitl, P. et al

in PHYSICAL REVIEW B (2018), 98(6), 064407

Using a combination of neutron diffraction with XYZ polarization analysis and magnetization measurements, the noncollinear magnetism in nanosized cobalt chromite, a potential multiferroic material, is ... [more ▼]

Using a combination of neutron diffraction with XYZ polarization analysis and magnetization measurements, the noncollinear magnetism in nanosized cobalt chromite, a potential multiferroic material, is revealed. For noninteracting 26.9(1) nm nanoparticles, a bulklike behavior is identified, including a ferrimagnetic Curie temperature of 99 K and a transition to the spin spiral magnetic phase at 27 K with a temperature-dependent, incommensurate propagation vector. A lock-in transition towards a commensurate propagation vector is not observed. Much smaller, 3.1(2) nm, nanoparticles reveal a strong cluster glass behavior, characterized by ferrimagnetic behavior below the Curie temperature of 43 K and a transition to asperomagnetic behavior at 18 K, with the absence of any magnetic reflections at a base temperature of 5 K. [less ▲]

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See detailSpin-wave dynamics in the helimagnet FeGe studied by small-angle neutron scattering
Siegfried, S.-A.; Sukhanov, A. S.; Altynbaev, E. V. et al

in PHYSICAL REVIEW B (2017), 95(13),

We have studied the spin-wave stiffness of the Dzyaloshinskii-Moriya helimagnet FeGe in a temperature range from 225 K up to TC ≈ 278.7 K by small-angle neutron scattering. The method we have used is ... [more ▼]

We have studied the spin-wave stiffness of the Dzyaloshinskii-Moriya helimagnet FeGe in a temperature range from 225 K up to TC ≈ 278.7 K by small-angle neutron scattering. The method we have used is based on [Grigoriev et al., Phys. Rev. B 92, 220415(R) (2015)] and was extended here for the application in polycrystalline samples. We confirm the validity of the anisotropic spin-wave dispersion for FeGe caused by the Dzyaloshinskii-Moriya interaction. We have shown that the spin-wave stiffness A for the FeGe helimagnet decreases with a temperature as A(T ) = 194[1 − 0.7(T/TC)4.2] meV °A2. The finite value of the spin-wave stiffness A = 58 meV °A2 at TC classifies the order-disorder phase transition in FeGe as being the first-order one. [less ▲]

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See detailAccessible length scale of the in-plane structure in polarized neutron off-specular and grazing-incidence small-angle scattering measurements
Maruyama, R.; Bigault, T.; Wildes, A. R. et al

in Journal of Physics Conference Series (2017), 862

Polarized neutron off-specular and grazing-incidence small-angle scattering measurements are useful methods to investigate the in-plane structure and its correlation of layered systems. Although these ... [more ▼]

Polarized neutron off-specular and grazing-incidence small-angle scattering measurements are useful methods to investigate the in-plane structure and its correlation of layered systems. Although these measurements give information on complementary and overlapping length scale, the different characteristics between them need to be taken into account when performed. In this study, the difference in the accessible length scale of the in-plane structure, which is one of the most important characteristics, was discussed using an Fe/Si multilayer together with simulations based on the distorted wave Born approximation. [less ▲]

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See detailThe small-angle neutron scattering instrument D33 at the Institut Laue-Langevin
Dewhurst, C. D.; Grillo, I.; Honecker, Dirk UL et al

in JOURNAL OF APPLIED CRYSTALLOGRAPHY (2016), 49

The D33 small-angle neutron scattering (SANS) instrument at the Institut Laue–Langevin (ILL) is the most recent SANS instrument to be built at the ILL. In a project beginning in 2005 and lasting seven ... [more ▼]

The D33 small-angle neutron scattering (SANS) instrument at the Institut Laue–Langevin (ILL) is the most recent SANS instrument to be built at the ILL. In a project beginning in 2005 and lasting seven years, the concept has been developed, and the instrument designed, manufactured and installed. D33 was commissioned with neutrons during the second half of 2012, fully entering the ILL user programme in 2013. The scientific case required that D33 should provide a wide dynamic range of measured scattering vector magnitude q, flexibility with regard to the instrument resolution, and the provision of polarized neutrons and 3He spin analysis to facilitate and expand studies in magnetism. In monochromatic mode, a velocity selector and a flexible system of inter-collimation apertures define the neutron beam. A double-chopper system enables a time-of-flight (TOF) mode of operation, allowing an enhanced dynamic q range (qmax/qmin) and a flexible wavelength resolution. Two large multitube detectors extend the dynamic q range further, giving qmax/qmin ’ 25 in monochromatic mode and a very large qmax/qmin > 1000 in TOF mode. The sample zone is large and flexible in configuration, accommodating complex and bulky sample environments, while the position of D33 is such as to allow high magnetic fields at the sample position. The instrument is of general purpose with a performance rivalling that of D22, and is well adapted for SANS studies in scientific disciplines as diverse as solution scattering in biology and soft matter and studies of physics, materials science and magnetism. This article provides a detailed technical description of D33 and its performance and characterization of the individual components, and serves as a technical reference for users of the instrument. [less ▲]

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See detailDroits de l'homme, droits fondamentaux et droit international privé
Kinsch, Patrick UL

Book published by Martinus Nijhoff Publishers (2005)

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See detailSport beginnt und endet im Kopf
Steffgen, Georges UL

Article for general public (1991)

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See detailDer Trainer auf dem Schleudersitz
Steffgen, Georges UL

Article for general public (1990)

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