Recently, neural network (NN) nonlinear equalizers which are expected to reduce computational complexity have attracted attention as fiber nonlinear compensation methods for coherent optical ...transmission systems. However, these fiber nonlinear compensation methods have problems that training of NN is not easy for long-distance transmission systems because of accumulated phase noise. In this letter, we propose a training method of NN nonlinear equalizer using the target outputs including phase noise which is produced by received signals. The phase noise is estimated by the inverse modulation of received signals and filtering. The estimated phase noise is added to transmitter signals, and the target outputs are obtained. The target outputs allow training of NN in long-distance coherent optical transmission systems. Since the NN trained by this proposed method compensates only for fiber nonlinearities, the phase locked loop (PLL) is placed after the NN to compensate for phase noise. The performances are evaluated by the simulation of 32 Gbaud 16QAM 4000 km long-distance coherent optical transmission. These results indicate that the proposed training method is effective in training NN nonlinear equalizer in long-distance coherent optical transmission in the presence of phase noise.
The motion of atoms in a solid always responds to cooling or heating in a way that is consistent with the symmetry of the given space group of the solid to which they belong. When the atoms move, the ...electronic structure of the solid changes, leading to different physical properties. Therefore, the determination of where atoms are and what atoms do is a cornerstone of modern solid-state physics. However, experimental observations of atomic displacements measured as a function of temperature are very rare, because those displacements are, in almost all cases, exceedingly small. Here we show, using a combination of diffraction techniques, that the hexagonal manganites RMnO3 (where R is a rare-earth element) undergo an isostructural transition with exceptionally large atomic displacements: two orders of magnitude larger than those seen in any other magnetic material, resulting in an unusually strong magneto-elastic coupling. We follow the exact atomic displacements of all the atoms in the unit cell as a function of temperature and find consistency with theoretical predictions based on group theories. We argue that this gigantic magneto-elastic coupling in RMnO3 holds the key to the recently observed magneto-electric phenomenon in this intriguing class of materials.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Z‐Rietveld is a program suite for Rietveld analysis and the Pawley method; it was developed for analyses of powder diffraction data in the Materials and Life Science Facility of the Japan Proton ...Accelerator Research Complex. Improvements have been made to the nonlinear least‐squares algorithms of Z‐Rietveld so that it can deal with singular matrices and intensity non‐negativity constraints. Owing to these improvements, Z‐Rietveld successfully executes the Pawley method without requiring any constraints on the integrated intensities, even in the case of severely or exactly overlapping peaks. In this paper, details of these improvements are presented and their advantages discussed. A new approach to estimate the number of independent reflections contained in a powder pattern is introduced, and the concept of good reflections proposed by Sivia J. Appl. Cryst. (2000), 33, 1295–1301 is shown to be explained by the presence of intensity non‐negativity constraints, not the intensity linear constraints.
Spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is an invasive economic pest of soft-skinned and stone fruit across the globe. Our study establishes both a ...predictive generalized linear mixed model (GLMM), and a generalized additive mixed model (GAMM) of the dynamic seasonal phenology of D. suzukii based on four years of adult monitoring trap data in Wisconsin tart cherry orchards collected throughout the growing season. The models incorporate year, field site, relative humidity, and degree days (DD); and relate these factors to trap catch. The GLMM estimated a coefficient of 2.21 for DD/1000, meaning for every increment of 1000 DD, trap catch increases by roughly 9 flies. The GAMM generated a curve based on a cubic regression smoothing function of DD which approximates critical DD points of first adult D. suzukii detection at 1276 DD, above average field populations beginning at 2019 DD, and peak activity at 3180 DD. By incorporating four years of comprehensive seasonal phenology data from the same locations, we introduce robust models capable of using DD to forecast changing adult D. suzukii populations in the field leading to the application of more timely and effective management strategies.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The present status of powder indexing software CONOGRAPH as an integrated system with a graphical user interface is reported. The improvements to the peak search method and the other available ...functions are introduced. Computational results and times for CONOGRAPH are compared with those for ITO13, N‐TREOR and DICVOL14 to clarify their differences.
A powder indexing software, CONOGRAPH, as an integrated system is reported.
High-temperature superconductivity appears as a consequence of doping charge carriers into an undoped parent compound exhibiting antiferromagnetic order; therefore, ground-state properties of the ...parent compound are highly relevant to the superconducting state. On the basis of this logic, spin fluctuations have been considered as the origin of pairing of the superconducting electrons in the cuprates. As possible pairing mechanisms, there is growing interest in unconventional spin fluctuations or advanced orbital fluctuations owing to the characteristic multi-orbital states in iron pnictides. Here, we report the discovery of an antiferromagnetic phase as well as a unique structural transition in electron-overdoped LaFeAsO1-x Hx (x thick ~ 0.5), whereby a second parent phase is uncovered, albeit heavily doped. The unprecedented two-dome superconducting phases observed in this material can be interpreted as a consequence of the carrier doping starting from the original x thick ~ 0 and additional x thick ~ 0.5 parent phases towards the intermediate region. The bipartite parent phases with distinct physical properties in the second magnetic phase provide us with an interesting example to illustrate the intimate interplay between the magnetic interaction, structural change and orbital degree of freedom in iron pnictide superconductors.
SnSe has drawn considerable attention on a global scale due to its intrinsic low thermal conductivity and large figure of merit along the b axis. In Na-doped SnSe, further enhancement of the ...thermoelectric performance has been reported. Using angle-resolved photoemission spectroscopy and inelastic neutron scattering, we have studied how electronic structures and lattice dynamics evolve with temperature in Na-doped SnSe. Our data show that the effective mass of the Se pz orbital along the Γ−Z direction has a very weak temperature dependence, while the chemical potential shifts significantly along with the increase in the gap size evidenced by infrared absorption measurements. Inelastic neutron scattering reveals one acoustic TA and two low-lying optical (TO1 and TO2) phonon modes. Their temperature-dependent behaviors indicate that the TO1 and TA modes contribute more to the reduction of the lattice thermal conductivity with temperature increases. The estimated value of the lattice thermal conductivity based on the lattice dynamics is significantly larger than that determined by transport measurements, suggesting that extrinsic factors, such as the imperfection of the lattice, could drastically suppress the lattice thermal conductivity. Our data suggest that temperature-dependent properties of both electronic structures and phonon dynamics need to be taken into account for the investigation of the underlying physics of hole-doped SnSe.
PLANET is a time-of-flight (ToF) neutron beamline dedicated to high-pressure and high-temperature experiments. The large six-axis multi-anvil high-pressure press designed for ToF neutron diffraction ...experiments enables routine data collection at high pressures and high temperatures up to 10GPa and 2000K, respectively. To obtain clean data, the beamline is equipped with the incident slits and receiving collimators to eliminate parasitic scattering from the high-pressure cell assembly. The high performance of the diffractometer for the resolution (Δd/d~0.6%) and the accessible d-spacing range (0.2–8.4Å) together with low-parasitic scattering characteristics enables precise structure determination of crystals and liquids under high pressure and temperature conditions.
With a focus on microstructural hierarchy, work hardening behaviour in high nitrogen-bearing austenitic steel (HNS) was investigated mainly by a combined technique of
in situ neutron diffraction and
...in situ electron backscattering diffraction (EBSD). Stress partitioning due to difference in deformability among grains is enhanced in HNS. The larger stress partitioning among
h
k
l-oriented family grains seems to realize high work hardening at a small strain. At a larger strain, dislocation density is higher in HNS than in low nitrogen austenitic steel (LNS), which is a possible reason for high work hardening after straining proceeds, resulting in large uniform elongation.
High-resolution time-of-flight powder neutron diffraction and high-field magnetization were measured to investigate the magnetic structure and existence of a field-induced magnetic phase transition ...in the distorted kagome antiferromagnet Cs2Cu3SnF12. Upon cooling from room temperature, the compound undergoes a structural phase transition at Tt=185K from the rhombohedral space-group R3¯m with the perfect kagome spin network to the monoclinic space-group P21/n with the distorted kagome planes. The distortion results in three inequivalent exchange interactions among the S=1/2Cu2+ spins that magnetically order below TN=20.2K. Magnetization measured with a magnetic field applied within the kagome plane reveals small in-plane ferromagnetism resulting from spin canting. On the other hand, the out-of-plane magnetization does not show a clear hysteresis loop of the ferromagnetic component nor a prominent anomaly up to 170 T with the exception of the subtle kneelike bend around 90 T, which could indicate the 1/3 magnetization plateau. The combined analysis using the irreducible representations of the magnetic space groups and magnetic structure refinement on the neutron powder-diffraction data suggests that the magnetic moments order in the magnetic space-group P21′/n′ with the all-in–all-out spin structure, which by symmetry allows for the in-plane canting, consistent with the in-plane ferromagnetism observed in the magnetization.
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