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.

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.

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.

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.

Electric-field-induced in-plane effective 90°magnetization rotation in Co2FeAl/PMN-PT structure

The in-plane effective 90°magnetization rotation of Co_(2) FeAl thin film grown on PMN-PT substrate induced by the electric field is investigated at room temperature.The magnetic hysteresis loops under different positive and negative electric fields are obtained,which reveals remanent magnetization can be mediated by the electric field.Moreover,under positive electric fields,the obvious 90°magnetization rotation can be observed,while remanent magnetization is nearly unchanged under negative electric fields.The result is consistent with the electric field dependence of effective magnetic field,which can be attributed to the piezostrain effect in Co_(2) FeAl/PMN-PT structure.In addition,the piezostrain-mediated 90°magnetization rotation can be demonstrated by the result of resonance field changing with electric field in the measurement of ferromagnetic resonance,which is promising for the design of future multiferroic devices.

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.

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.

TWO-PHASE FLOW PATTERNS IN A 90° BEND AT MICROGRAVITY

Bends are widely used in pipelines carrying single-and two-phase fluids in both ground and space applications.In particular,they play more important role in space applications due to the extreme spatial constraints.In the present study,a set of experimental data of two-phase flow patterns and their transitions in a 90°bend with inner diameter of 12.7 mm and curvature radius of 76.5 mm at microgravity conditions are reported.Gas and liquid superficial velocities are found to range from (1.0～23.6)m/s for gas and(0.09～0.5)m/s for liquid,respectively.Three major flow patterns, namely slug,slug-annular transitional,and annular flows,are observed in this study.Focusing on the differences between flow patterns in bends and their counterparts in straight pipes,detailed analyses of their characteristics are made.The transitions between adjoining flow patterns are found to be more or less the same as those in straight pipes,and can be predicted using Weber number models satisfactorily. The reasons for such agreement are carefully examined.

地震沉积学中90°相位转换技术适用性的讨论

地震沉积学理论及应用技术研究中90°相位转换技术是地震沉积学研究的核心技术之一,但在实际研究与应用中,该技术并未取得如期的成果。在地震勘探原理中,地震反射同相轴代表着具有波阻抗差的地层界面。90°相位转换拟通过相移的方式,将代表着地层界面的地震反射同相轴赋于岩性地层的意义。由于地下地层的复杂多变,多种岩性频繁薄互层。利用薄互层地质模型的地震正演模拟结果,证实地震反射同相轴并不能与地层界面一一对应,因此,地震剖面中的同相轴是多套薄互层组合效应。受地震资料分辨力的限制,90°相位转换后的地震资料既不能将原始地震资料由界面型地震剖面转换成岩性地层剖面,也缺乏明确的地质含义,其在地震构造解释和地震岩性解释中的应用能力均很有限,所以很难称其为地震沉积学的应用技术。因此,将90°相位转换技术作为地震沉积学的核心技术并不合适,该技术无法提高地震资料分辨能力,也不能精确地将地震剖面转化成岩性剖面。

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.

Nonlinear Polarization Rotation Characteristic Phenomenon in a Bulk Semiconductor Optical Amplifier

The phenomena of polarization rotation induced by self-modulation in semiconductor optical amplifier (SOA) are analyzed theoretically. The relationship between polarization parameters and gain as well as phase is obtained by the correlation parameter of ellipse polarization and SOA nonlinearity polarization rotation theory. The experiment employs polarizer drive by walking electromotor and power meter, the light power of 360 degree is measured. The transformation law of output polarization power components is found for obvious polarization rotation in the selected coordinate axes based on connection of polarization state in difference axes. Using this law make the manipulation easily on getting ideal polarization state. It can offer a fine method to realize all-optical switch and other logic elements in experiment. This work is of great significance for the applications of SOA nonlinear polarization rotation at high-speed all-optical signal processing and all-optical logic gate.

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.

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.

90°相位旋转技术在储层预测中的应用——以鄂尔多斯盆地彬长区块长8-1油层组为例

鄂尔多斯盆地彬长区块延长组长81是鄂尔多斯盆地南缘主要勘探开发层系之一,其上覆长73底部发育的张家滩页岩形成的地震强反射界面及长81储层较薄的地质沉积特征,造成常规地震数据体预测储层多解性较强。通过对张家滩页岩与长81储层速度、反射强度对比分析及组合模式的研究,提出了彬长区块长81油层组基于90°相位旋转技术的三维地震属性优选储层预测方法。运用90°相位旋转使地震反射的主要同相轴与地质上的储层有较好的对应,使地震相位具有岩性地层意义;运用正演模型分析、反射结构对比及多时窗属性优选等技术对目标储层进行预测,认为90°相位旋转下一定时窗内的反射强度及振幅属性能较好地对长81储层进行了预测。

90°相位转换技术在预测砂体展布中的应用

以黄河口凹陷西洼沙河街二段为例,对研究区地震剖面进行90°相位转换,根据转换后的剖面岩性特征及地质背景概况建立地质模型,进行正演模拟分析;然后对比零相位与90°相位的正演合成记录,校准地质模型,并依据地震剖面振幅属性特征,对相位转换后的地震剖面进行属性提取,预测砂体的展布。研究发现,基于90°相位转换地震剖面建立的地质模型更具直观性,正演合成记录验证砂岩恰好对应于波谷,波形能清晰地展示出砂岩层的纵向轮廓,并且90°相位转换的地震波谷振幅值属性平面图能清晰显示出砂体的平面展布及分布范围。

产生蓝色相干辐射和实现Nd∶YAG 1.0642μm倍频90°非临界相位匹配的Nb∶KTiPO_4(英文)

本文报道了用熔盐顶部籽晶法生长Ｎｂ浓度（０～１３）ｍｏｌ％的Ｎｂ∶ＫＴＰ晶体的倍频的Ⅱ型相位匹配的截止波长和Ｎｄ∶ＹＡＧ１．０６４２μｍ及Ｎｄ∶ＹＡ１Ｏ３１．０７９５μｍ激光在这些晶体中倍频的最佳相位匹配角的测量结果．从中可看出，由于Ｎｂ５＋的引入使ＫＴＰ晶体倍频的Ⅱ相位匹配的截止波长有效蓝移，目前已使截止波长蓝移至９３７ｎｍ且有效产生４６８．５ｎｍ的倍频蓝光．同时Ｎｂ５＋的引入使Ｎｄ∶ＹＡＧ１．０６４２μｍ激光和Ｎｄ∶ＹＡ１Ｏ３倍频的最佳相位匹配方向产生很大的变化，目前已使Ｎｂ∶ＫＴＰ晶体倍频的最佳相位匹配方向为θ＝８８．３２°、Φ＝０°。

束转动90°非稳腔设计方法

采用束转动９０°非稳腔（ＵＫ９０）将是获取低增益高功率激光器良好光束质量的极有效方法。用矩阵法对理想准直的ＵＫ９０作了模型分析计算，为其基本参数的设计提供了方法。

不同重力下90°弯管内气液两相流流型及流动特性研究

研究了不同重力条件下90°弯管内气液两相流流型分布形态及流动特性.通过建立90°弯管内气液两相流流动的三维数学物理模型,采用VOF方法,对10-6g0,10-4g0,10-2g0,1g0(g0=9.8 m/s2)重力下的90°弯管内气液两相流流型分布特征、截面空隙率、滑速比及气相尾部最大斜向角进行了比较分析.研究结果表明:所建立的模型能够正确模拟不同重力条件下90°弯管内气液两相流流型和截面空隙率,并得到气液两相弯管二次流与单相二次流的不同特性.随着重力水平的提高,90°弯管对气相流型的影响作用减弱,气相整体向弯管内侧积聚靠拢,弯管对尾部的斜向作用减弱.