Numerical Simulations of Snow Accumulation in the Bogie Region of a Train Considering Snow Particle Rotation

To investigate the influence of snow particle rotational motion on the accumulation of snow in the bogie region of high-speed trains,an Euler‒Lagrange numerical approach is adopted.The study examines the effects of snow particle diameter and train speed on the ensuing dynamics.It is shown that considering snow particle rotational motion causes significant deviation in the particle trajectories with respect to non-rotating particles.Such a deviation increases with larger snow particle diameters and higher train speeds.The snow accumulation on the overall surface of the bogie increases,and the amount of snow on the vibration reduction device varies greatly.In certain conditions,the amount of accumulated snow can increase by several orders of magnitudes.

Synchronization for the Environment of OFDM Cooperative Communications Based on Preamble Design and Phase Rotation

Timing and carrier frequency offset estimation are critical issue for OFDM cooperative communications. In view of the complexity and high accuracy requirement, 1/2 and 1/4 pilot symbol cycle CAZAC sequence structures are defined as the pilot frequency sequence. Estimation within one symbol cycle is carried out through averaging samples of two neighboring symbol cycles, after which the operation is expanded to all the symbol cycles in one band group. Taking multipath effect into account, the concept of phase rotation is proposed for a further step. Adjust the phase difference of estimated symbols by phase rotation, and cross estimation could be done. Meanwhile, timing scheme works within one cycle training sequence. Theoretical and simulation analysis indicate that CRLB does not only relate to estimation symbol length, but also be influenced by phase difference of estimation symbols seriously. In the condition that the length of estimation is fixed, the bigger the phase rotation angle is, the smaller the CRLB is. The complexity of proposed algorithm is less than full cycle average estimation method for almost 50%. Meanwhile, the estimation accuracy is approximate with the full cycle average estimation method as well. Timing scheme with the defined preamble structure is also proposed. Simulation proves its efficiency.

基于PR—Henry改进模型的酸性天然气——地层水体系及其相平衡特征分析

准确表征酸性天然气—地层水体系的相平衡规律,对于天然气开发过程中的水溶气量和凝析水量分析具有重要意义,但目前常用的PR状态方程与Henry定律等理论对酸性天然气—地层水体系的相平衡研究还存在不适用的问题。为进一步考虑酸性气体和地层水矿化度对体系相平衡的影响,改进并提高对天然气溶解度和饱和含水量的计算精度,在PR状态方程与Henry定律相结合建立的PR—Henry模型基础上,考虑了溶解盐对体系相平衡的影响,采用定标粒子理论(SPT)修正了Henry常数,建立了改进的PR—Henry模型,最后分析了天然气组成、压力、温度和盐水含盐量对天然气溶解量和饱和含水量的影响。研究结果表明:(1)模型计算结果与实测资料对比,平均相对偏差分别为5.3%和4.55%,表明该模型能够应用于不同温度、压力和组成的酸性天然气-地层水体系的相平衡计算;(2)天然气在地层水中的溶解量受天然气组成、温度、压力和地层水含盐量的影响;(3)天然气饱和含水量受温度和压力影响十分明显。结论认为,改进的PR—Henry模型为天然气开采过程评价和CO_(2)埋存溶解量计算提供了一种有效的方法,对于评估天然气可采储量及开发特征具有重要的参考意义。

Rotational and translational domains of beta precipitate in aged binary Mg-Ce alloys

The structural evolution fromβ_(1)(Mg_(3)Ce)toβ(Mg_(12)Ce)precipitates,which takes place at the over-aged stage of binary Mg-Ce alloys,are investigated by high-angle annular dark-field scanning transmission electron microscopy.The structural transformation mainly occurs in the{111}_(β1)crystallographic planes,where the newly formedβlattices exhibit two categories of domain structures,namely rotational and translational domains.The rotational domain is composed of threeβdomains(β_(RA),β_(RB)andβ_(RC)),which are related by a 120°rotation with respect to each other around the 111_(β1)axis of theirβ_(1)parent phase.The{111}_(β1)crystallographic planes can provide four sets of sublattices with the same orientation for an initial nucleation ofβlattice.It leads to the formation of four translationalβdomains(β_(TA),β_(TB),β_(TC)andβ_(TD)),among which any two differ by a vector of 1/6112_(β1).We deduce theoretically that there exist twenty-fourβdomains during this transition.However,considering the interfacial misfit,only one-third of domains can grow up and eventually formsβribbon.Furthermore,a majority ofβribbons overlap partiallyβ_(1)plate,which is beneficial to relax interfacial strain amongβ,β_(1)andα-Mg matrix(α/β/β_(1)).The configuration of multipleβdomains can effectively regulate interfacial misfit ofα/βandβ/β_(1),which are responsible for enhancing the hardness and strength of Mg-Ce alloy.Additionally,this study aims to provide some clues to improve the over-aged performance of magnesium alloys by constructingβdomains and optimizing theα/β/β_(1)interface.

Magnetic Interactions with Strain Gradient in Ultrathin Pr_(0.67)Sr_(0.33)MnO_(3) Films

Strain gradient is a normal phenomenon around a heterostructural interface in ultrathin film,and it is important to determine its effect on magnetic interactions to understand interfacial coupling.In this work,ultrathin Pr_(0.67)Sr_(0.33)MnO_(3)(PSMO)films on different substrates are studied.For PSMO film under different in-plane strain conditions,the saturated magnetization and Curie temperature can be qualitatively explained by double-exchange interaction and the Jahn-Teller distortion.However,the difference in the saturated magnetization with zero field cooling and 5 T field cooling is proportional to the strain gradient.Strain-gradient-induced structural disorder is proposed to enhance phonon-electron antiferromagnetic interactions and the corresponding antiferromagnetic-to-ferromagnetic phase transition via a strong magnetic field during the field cooling process.A non-monotonous structural transition of the MnO_(6) octahedral rotation can enlarge the strain gradient in PSMO film on a SrTiO_(3) substrate.This work demonstrates the existence of the flexomagnetic effect in ultrathin manganite film,which should be applicable to other complex oxide systems.

Characterization and Application of S-Band Polarimetric Radar and X-Band Phased Array Radar for a Tornadic Storm Event on June 16,2022

The X-band phased array radar offers faster scanning speed and higher spatial resolution compared to the S-band radar,making it capable of enhancing tornado monitoring and early warning capabilities.This study analyzed the characteristics and nowcasting signals of a tornado case that occurred on June 16,2022 in the Guangzhou region.Our findings indicate that the violent contraction of rotation radius and the dramatic increase in rotation speed were important signal characteristics associated with tornado formation.The X-band phased array radar,with its high temporal and spatial resolution,provided an opportunity to capture early warning signals from polarimetric characteristics.The X-band phased array radar demonstrated noteworthy ability to identify apparent tornado vortex signature(TVS)features in a 10-minute lead time,surpassing the capabilities of the CINRAD/SA radar.Additionally,due to its higher scanning frequency,the Xband phased-array radar was capable of consistently identifying TVS with shorter intervals,enabling a more precise tracking of the tornado's path.The application of professional radars,in this case,provides valuable insights for the monitoring of evolutions of severe local storms and even tornadoes and the issuance of early warning signals.

A new method for resolving phase ambiguity in radio interferometry using Earth rotation synthesis

As a key technique in deep space navigation, radio interferometry can be used to determine the accurate location of a spacecraft in the plane-of-sky by measuring its signal propagation time delay between two remote stations. To improve the measurement accuracy, differential phase delay without phase ambiguity is usually desired. Aiming at the difficulties of resolving phase ambiguity with few stations and narrowband downlink signals, a new method is proposed in this work by taking advantage of the Earth rotation. The high accurate differential phase delay between the spacecraft and a calibrator can be achieved not only in the in-beam observation mode but also in the out-of-beam observation mode. In this paper we firstly built the model of phase ambiguity resolution. Then, main measurement errors of the model are analyzed, which is followed by tests and validations of the model and method using the tracking data of the Cassini mission and Chang'E-3 mission. The results show that the phase ambiguities can be correctly resolved to generate a 10-picosecond level accuracy differential phase delay. Angular measurement accuracy of the Cassini reaches the milli-arc-second level, and the relative position accuracy between the Chang'E-3 rover and lander reaches the meter level.

Behavior of quantum search algorithm with small phase rotations

When the Grover＇ s original algorithm is applied to search an unordered database, the success probability decreases rapidly with the increase of marked items. Aiming at this problem, a general quantum search algorithm with small phase rotations is proposed. Several quantum search algorithms can be derived from this algorithm according to different phase rotations. When the size of phase rotations are fixed at 0. 01π, the success probability of at least 99. 99% can be obtained in 0（√N/M） iterations.

Effects of rotation and gravity on an electro-magneto-thermoelastic medium with diffusion and voids by using the Lord-Shulman and dual-phase-lag models

The effects of rotation and gravity on an electro-magneto-thermoelastic medium with diffusion and voids in a generalized thermoplastic half-space are studied by using the Lord-Shulman (L-S) model and the dual-phase-lag (DPL) model. The analytical solutions for the displacements, stresses, temperature, diffusion concentration, and volume fraction field with different values of the magnetic field, the rotation, the gravity, and the initial stress are obtained and portrayed graphically. The results indicate that the effects of gravity, rotation, voids, diffusion, initial stress, and electromagnetic field are very pronounced on the physical properties of the material.

低温快烧Pr-Ce-ZrSiO_(4)黄色色釉的制备研究

笔者采用正交试验法,优化无熔块基釉配比,并以此为基础,加入固相法合成Pr-Ce-ZrSiO_(4)黄色陶瓷色料,制备一种适应于低温快烧的建筑陶瓷黄色色釉,研究煅烧温度、Pr/Ce摩尔比对于色釉呈色的影响。实验结果表明,基釉配比为硼钙石∶锂长石∶石英∶萤石∶BaCO_(3)∶SrCO_(3)=15∶52∶20∶4∶5∶8时,能够获得良好的釉面质量与光泽度;而对于Pr-Ce-ZrSiO_4黄色色料,在1200℃的煅烧温度下,Pr^(4+)能够最大限度进入到ZrSiO_(4)晶体中,使得釉面产生良好的着色效果;当Pr/Ce摩尔比为1∶0.55时,Ce^(4+)与Pr^(4+)能够取代Zr^(4+)形成有限固熔体,降低色釉釉面的绿色色调,使得釉面色度由黄色过渡到橙黄色。

Geometric phases in qubit-oscillator system beyond conventional rotating-wave approximation

In this work we investigated the geometric phases of a qubit-oscillator system beyond the conventional rotating- wave approximation. We find that in the limiting of weak coupling the results coincide with that obtained under rotating-wave approximation while there exists an increasing difference with the increase of coupling constant. It was shown that the geometric phase is symmetric with respect to the sign of the detuning of the quantized field from the one-photon resonance under the conventional rotating-wave approximation while a red-blue detuning asymmetry occurs beyond the conventional rotating-wave approximation.

Ellipsometric configurations using a phase retarder and a rotating polarizer and analyzer at any speed ratio

In this paper, we propose an ellipsometer using a phase retarder and rotating polarizer and analyzer at a speed ratio I：N. Different ellipsometric configurations are presented by assuming N = 1, 2, and 3. Moreover, two values of the offset angle of the retarder are considered for each ellipsometric configuration. The Mueller formalism is employed to extract the Stokes parameters, from which the intensity received by the detector is obtained. The optical properties of c-Si are calculated using all configurations. A comparison between different configurations is carried out considering the effect of the noise on the results and the uncertainties in the ellipsometric parameters as functions of the uncertainties of the Fourier coefficients. It is found that the alignment of the phase retarder has a crucial impact on the results and the ellipsometric configuration with speed ratio 1：1 is preferred over the other configurations.

Prediction of mass transfer coefficients in an asymmetric rotating disk contactor using effective diffusivity

Mass transfer characteristics have been investigated in a 113 mm diameter asymmetric rotating disk contactor of the pilot plant scale for two different liquid–liquid systems. The effects of operating parameters including rotor speed and continuous and dispersed phase velocities on the volumetric overall mass transfer coefficients are investigated. The results show that the mass transfer performance is strongly dependent on agitation rate and interfacial tension, but only slightly dependent on phase flow rates. In this study, effective diffusivity is used instead of molecular diffusivity in the Grober equation for estimation of dispersed phase overall mass transfer coefficient.The enhancement factor is determined experimentally and there from an empirical expression is derived for prediction of the enhancement factor as a function of Reynolds number. The predicted results compared to the experimental data show that the proposed correlation can efficiently predict the overall mass transfer coefficients in asymmetric rotating disk contactors.

Phase Transformation and Magnetic Properties of Mechanically Alloyed PrCo5-based Magnets

PrCo5-based nanograin Pr=CO100-x （x=14-22） alloys with high coercivity were synthesized by mechanical alloying and subsequent annealing. The crystallization, phase components and magnetic properties of the alloys were investigated systematically. The main phase of the alloy for x=14 is Pr2CO17 with rhombohedral Th2Zn17-type. The amount of the Pr2CO17 phase decreases with increasing Pr content, and a nearly single phase PrCo5 with hexagonal CaCu5-type is formed in Pr18Co81 alloy. Further increase in the Pr content leads to the formation of another magnetically hard Pr2Co7 phase with its Curie temperature about 350℃. Remanences decrease monotonously with increasing Pr content, whereas the coercivities increase, reaching a maximum of 2040 kA/m （25.6 kOe） in Pr19CO81 powders milled for 5 h and annealed at 973 K for 2 min, and then decrease for higher Pr content. The high coercivity is attributed to the high anisotropy field of the PrCo~ phase and its nanoscale grain size.

A Precise Calibration Method on Phase Center of Uplink Antenna Array Considering Its Actual Pointing

With regard to the inferior techniques and low accuracy of phase center calibration of an antenna array, this paper proposes a new calibration method considering the actual antenna pointing by introducing a precise engineering surveying technique to measure the real state of antennas. First, an industrial photogrammetric system is utilized to obtain the coordinates of points on antenna panels in different postures, and the actual pointing of the mechanical axis is obtained via least-squares fitting. Then, based on this, the coordinates of antenna rotation center are obtained by seeking the intersection of mechanical axes via using the matrix method. Finally, the mechanical axis in arbitrary postures is estimated based on the inverse-angle weighting interpolation method, and the reliable phase center is obtained by moving a fixed length from the projective center along the mechanical axis. An uplink antenna array including three ? 3 m antennas is taken as experimental object, and all photogrammetric coordinate systems are unified by the engineering control network, with each antenna phase center precisely calibrated via the proposed method. The results of electrical signal synthesis indicate that this method can effectively overcome the influence of gravity deformation and mechanical installation error, and enhance the synthetic signal magnitude of the uplink antenna array.

Isothermal Section of Phase Diagram of the Ternary System Co-Dy-Pr at 500℃

The isothermal section of the phase diagram of the ternary system Co Dy Pr at 500℃ was investigated by X ray diffraction analysis, optical microscopy, electron microscopy, electron spectrum and electron probe miscroanalysis techniques. The section consists of seventeen single phase regions, twenty eight two phase regions and twelve three phase regions. Three of single phase regions are the solid continuums and three of single phase regions are the wide limit solid solutions. No ternary compound was observed in this system.

EFFECTS OF NITRIDING TEMPERATURE ON MAGNETIC PROPERTIES OF MELT-SPUN Pr1.4Fe10.5Mo1.5Nx AND ITS PHASE ANALYSIS

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Phase Relationship in (Dy_(0.65)Tb_(0.25)Pr_(0.1))Fe_x Alloys (1.6≤x≤2.1)

The microstructure and phase relationship of (Dy0.65Tb0.25Pr0.1)Fex alloys in the composition range of 1.6≤x≤2.1 were investigated using optical microscopy, X-ray diffraction , DTA and EPMA techniques. The variations of microstructure and lattice parameter with the iron content,the effect of heat treatment on the microstructure and the phase relationship have been studied.The phase relationship in the vicinity of the Laves phase is proposed

Simple Landau Model of the Liquid-RII-RI Rotator Phases of Alkanes

Simple Landau free energy function is presented to describe the Liquid-RII-RI phase sequence of alkanes and transitions between them. The order parameters necessary to describe these rotator phase transitions are identified. We present a mean-field description of the Liquid-RII and Liquid-RI transitions. General arguments are presented for the topology of the phase diagram in the vicinity of the Liquid-RII-RI triple point. Within this model the Liquid-RII and Liquid-RI transitions are found to be always strongly first order. Calculations based on this model agree qualitatively with experiments.

Bilaterally Symmetrical Transformation between Independent Operators and Rotations

This report describes an approach for representation of quantum operators through rotations and rotation through quantum operators. The approach of the proposed method transforms rotation in a kind of a unitary matrix that corresponds to the rotation. Operations with qubits are very similar to the rotation, but with an added phase coefficient. This fact is used to create a process for rotation between unitary matrices. This approach could be used to modifying the controls to apply in a different basis.