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Anisotropy of acoustic and thermal expansion properties of TlInSe <sub/>2</sub> crystals
摘要： Based on experimental studies of acoustic wave velocities in TlInSe2 crystals, all components of their elastic stiffness and compliance tensors are determined. TlInSe2 has three acoustic axes parallel to the principal crystallographic directions. The lowest velocities of acoustic eigenwaves are used to estimate the acousto-optic figure of merit. We analyse deviations from purely longitudinal and transverse polarization states, as well as the obliquity of acoustic energy flow. Temperature dependences of strains along the three principal crystallographic directions and of acoustic wave velocities v11, v22 and v33 are measured. Anomalous behaviour of these parameters occur at T1≈245 K and T2≈145 K. It is shown that the symmetry of TlInSe2 becomes lower than tetragonal below the temperature point T1.
关键词： TlInSe2 crystals,Ferroics,elastic properties,thermal expansion,anisotropy,acoustic wave velocity
更新于2025-09-23 15:21:21
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A single-cell-gap transflective liquid crystal display with a vertically aligned cell
摘要： A single-cell-gap transflective liquid crystal display with a vertically aligned cell using square ring electrode is demonstrated. The top substrate has a top planar common electrode, a square ring pixel electrode is coated on the bottom substrate, while a bumpy reflector is coated under the bottom substrate. In this device, the planar common electrode and square ring pixel electrode generate a strong longitudinal electric field in the transmissive region (T region) and a weak fringe field in the reflective region (R region). As result, the T and R regions accumulate the same optical phase retardation. The simulation results show that the display exhibits reasonably low operating voltage, high transmittance and well-matched voltage-dependent transmittance and reflectance curves. Besides, fabrication process of the transflective liquid crystal display is very simple.
关键词： square ring electrode,Vertically aligned cell,negative dielectric anisotropy,single-cell-gap,transflective liquid crystal display
更新于2025-09-23 15:21:21
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Effects of Anisotropy Field and Easy Axis Dispersions on Squareness Ratio for HDDR-Processed Nd-Fe-B Powders
摘要： Nd-Fe-B magnetic powders produced by the hydrogenation-decomposition-desorption-recombination process have a lower squareness ratio than sintered magnets. In this paper, the anisotropy ?eld (Hk) distribution was assumed to be a horizontally ?ipped lognormal distribution and the effect of the Hk dispersion on the squareness ratio was investigated by using a micromagnetic simulator. As a result, the squareness ratio was very similar to the experimental demagnetization loop, when (cid:2)Hk(cid:3) was 5500 kA/m and σ Hk/(cid:2)Hk(cid:3) was 30%. Moreover, we investigated the easy axis dispersion of grains on squareness ratio in consideration of soft magnetic or nonmagnetic grain boundaries. As a result, the squareness ratio for the nonmagnetic grain boundary was closer to the experimental value; however, it is dif?cult to describe the experimental demagnetization loop by only considering the easy axis dispersion.
关键词： hydrogenation-decomposition-desorption-recombination (HDDR)-processed Nd-Fe-B,horizontally ?ipped lognormal distribution,Anisotropy ?eld and easy axis dispersions,squareness ratio
更新于2025-09-23 15:21:21
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Influence of 4-[(E)-(4′-Heptyloxyphenyl)diazenyl]phthalonitrile on the Properties of a Cyanobiphenyl Liquid Crystal Mixture
摘要： The mesomorphic properties of 4-[(E)-(4'-heptyloxyphenyl)diazenyl]phthalonitrile (7O-AB-CN2) were studied by polarization microscopy and DSC method. Liquid crystalline phase formation was observed over a broad temperature range of 92 to 181°C. The influence of 7O-AB-CN2 on the mesomorphic, dielectric, and optical properties of a liquid crystalline mixture of n-alkyloxycyanobiphenyls was examined. Enhancement of the dielectric anisotropy of the mesomorphic composition due to high polarity of 7O-AB-CN2 and its effective inclusion into the liquid crystalline matrix was revealed.
关键词： dielectric anisotropy,cyanobiphenyls,birefringence,liquid crystals,phthalonitrile,azobenzenes
更新于2025-09-23 15:21:21
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Anisotropic third-order nonlinearity in pristine and lithium hydride intercalated black phosphorus
摘要： Two-dimensional (2D) black phosphorus (BP) displays unique anisotropic properties in its linear optical responses, but its third-order nonlinearity (Kerr effect) has remained relatively unexplored. Here we measured the third-order nonlinear optical responses in exfoliated BP and in lithium hydride intercalated BP (LiH-BP) flakes using polarization-resolved microscopic femtosecond Z-scan technique. Strong optical Kerr nonlinearities were measured for single flakes of BP and LiH-BP, with third-order nonlinear susceptibilities that are larger than many 2D materials. The nonlinear coefficients of LiH-BP are higher than those of BP, indicating that lithium hydride intercalation enhances not only the ambient stability of BP but also its nonlinear optical response. Highly anisotropic polarization-dependent Kerr nonlinearities of both BP and LiH-BP flakes were observed. The strong nonlinear and anisotropic optical responses of BP and LiH-BP indicate great potential of these materials in nonlinear photonics device applications.
关键词： in-plane anisotropy,nonlinear optical responses,lithium hydride intercalated black phosphorus,Kerr nonlinearity,Black phosphorus
更新于2025-09-23 15:21:21
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Research on image de-disturbing algorithm based on dark channel prior and anisotropic Gaussian filtering
摘要： In order to solve the problem of serious degradation of images collected outdoors in dense fog weather, a defogging algorithm for dense fog images was proposed. The fog-day imaging physical model was simplified; the concept of fog concentration factor was proposed. The single image de-hazing algorithm based on dark channel priors solves the problem of estimating the transmittance of fog and sky scenes. The image recovered by the algorithm is clear and natural. The algorithm has high computational complexity. It takes a long time to meet real-time requirements. The principle of anisotropic Gaussian filtering is introduced. It combines with the dark channel. The value of the fog concentration coefficient is obtained by estimating the visibility value of a single fog image. It is then combined with an anisotropic Gaussian filter of the image to estimate the atmospheric light value. Defogging of the fog image is performed by using the repair function. It is necessary to perform effective de-hazing processing on smog images. Experiments show that the improved algorithm can greatly reduce the complexity of the algorithm while ensuring the defogging effect of the original algorithm.
关键词： anisotropy,Gaussian filter,foggy image removal,dark channel prior principle
更新于2025-09-23 15:21:21
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Simulation of Full Responses of Triaxial Induction Logging in 1D Layered Arbitrarily Anisotropic Formations
摘要： Triaxial induction tools can be used to evaluate thinly laminated sand-shale sequences and fractured beds. This type of reservoirs exhibit transversely isotropy (TI) or arbitrarily anisotropy (also called as biaxial anisotropy (BA)). There have been several papers to study the responses in the TI model or the simpli?ed BA model whose conductivity principal coordinate is always consistent with the formation coordinate. However, little work covers the most general biaxial anisotropic model whose conductivity tensor’s orientation is arbitrary. We introduce the Euler angles, then the general biaxial anisotropic conductivity tensor can be determined by three principal components and three ordered Euler angles. To derive the electromagnetic (EM) ?elds in arbitrarily anisotropic medium, we ?rst convert the Maxwell’s equation of frequency-spatial domain into frequency-wavenumber domain by 2D Fourier transform, and obtain an ordinary di?erential system about horizontal components of EM ?elds. Using eigenvalue decomposition of the system matrix, this system can be decomposed into two group of equations associated with upward and downward eigen-waves respectively. We derive the solutions of EM ?elds in frequency-wavenumber domain by introducing transmission matrix, both local and generalized re?ection matrix and propagator matrix After that, we use 2D Gauss-Legendre quadrature to calculate inverse Fourier transformation and obtain Green’s function for simulation of the tri- axial induction responses. The numerical results are compared with 3D numerical method in both vertical and deviated wells and the agreement is satisfactory. Finally, we investigate the response characteristics in several formations with di?erent Euler angles The results show that triaxial induction responses are remarkably in?uenced by Euler angles even if the values of three principal components of conductivity tensor remain unchanged. Compare to the responses of the simpli?ed BA model, those of general BA model are more complex and contain more nonzero components. The results indicate that using TI model or the simpli?ed BA model in complex environment may cause large errors. Our algorithm are more practical than algorithms based on the simpli?ed model because the real depositional environments are usually complicated.
关键词： Maxwell’s equation,biaxial anisotropy,eigenvalue decomposition,Triaxial induction logging,Euler angles,Fourier transform,Gauss-Legendre quadrature
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC) - Ixtapa, Mexico (2019.11.13-2019.11.15)] 2019 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC) - Electrical characteristics of ternary solar cells based on PTB7:PCBM:ICBA
摘要： Multivariable dynamic ankle mechanical impedance in two coupled degrees-of-freedom (DOFs) was quanti?ed when muscles were active. Measurements were performed at ?ve different target activation levels of tibialis anterior and soleus, from 10% to 30% of maximum voluntary contraction (MVC) with increments of 5% MVC. Interestingly, several ankle behaviors characterized in our previous study of the relaxed ankle were observed with muscles active: ankle mechanical impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness; stiffness was greater in the sagittal plane than in the frontal plane at all activation conditions for all subjects; and the coupling between dorsi?exion–plantar?exion and inversion–eversion was small—the two DOF measurements were well explained by a strictly diagonal impedance matrix. In general, ankle stiffness increased linearly with muscle activation in all directions in the 2-D space formed by the sagittal and frontal planes, but more in the sagittal than in the frontal plane, resulting in an accentuated “peanut shape.” This characterization of young healthy subjects’ ankle mechanical impedance with active muscles will serve as a baseline to investigate pathophysiological ankle behaviors of biomechanically and/or neurologically impaired patients.
关键词： stiffness anisotropy,Ankle joint,ankle stiffness,impedance structure,human ankle,ankle joint stiffness,multivariable stiffness,multivariable impedance
更新于2025-09-23 15:21:01
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Kinetics of two-pulsed photon echo formed on the 0–1 transition: isotropic and anisotropic collisions
摘要： The photon echo formed at the intercombination (6s2) 1S0 ? (6s6p) 3P1 (type 0–1) transition of ytterbium atoms 174Yb by two pulses of resonance radiation was investigated as a function of the time delay between exciting pulses (the photon echo kinetics). For exciting radiation pulses of the same linear polarization in the delay region 70–250 ns, the photon echo kinetics is close to the exponential one both in pure ytterbium and in its mixtures with buffer gases Ar and Xe. The relaxation cross sections were determined for all three cases, taking into account the isotopic composition of xenon and ytterbium. For the first time, the complex nonmonotonous kinetics of the collision-induced photon echo was observed in the same mixtures for the forming pulses of linear mutually orthogonal polarization. The relative efficiency of buffer atoms Yb (other isotopes than 174Yb), Xe and Ar in the collision-induced photon echo formation was obtained.
关键词： collision induced photon echo,collision anisotropy,photon echo
更新于2025-09-23 15:21:01
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[Methods in Enzymology] || Fluorescence Depolarization Kinetics to Study the Conformational Preference, Structural Plasticity, Binding, and Assembly of Intrinsically Disordered Proteins
摘要： Fluorescence depolarization kinetics measured by the time-resolved fluorescence anisotropy decay serves as a sensitive and powerful methodology to study the conformational dynamics of macromolecules. This methodology allows us to delineate the different modes of biomolecular motional dynamics including the local, segmental, and global rotational dynamics on the timescale ranging from picoseconds to nanoseconds. In this chapter, we describe the principles and applications of this methodology to obtain unique molecular insights into the intrinsically disordered proteins (IDPs). Fluorescence depolarization kinetics, when performed in a site-specific manner, can offer a reliable tool to monitor the intrinsic backbone torsional dynamics of expanded IDPs and is capable of discerning the conformational preference of IDPs. Additionally, the time-resolved fluorescence anisotropy measurements allow us to investigate the mechanism of binding and assembly of a wide range of IDPs that are involved in crucial function and disease.
关键词： Fluorescence depolarization kinetics,conformational dynamics,time-resolved fluorescence anisotropy decay,biomolecular interactions,intrinsically disordered proteins
更新于2025-09-23 15:21:01