磁性薄膜自旋重取向行为的Monte Carlo模拟

利用MonteCarlo方法模拟了二维简单立方结构磁性薄膜的自旋重取向行为,重点研究了各向异性和偶极相互作用对系统自旋取向的影响.通过计算,获得了系统的相图以及系统组态、磁分量、比热等随偶极相互作用和温度的变化规律.模拟结果表明,在一定的参数范围内,随着温度的升高,系统的自旋取向将由垂直向平行方向转变.

钙钛矿锰氧化物电荷有序体系中自旋玻璃行为研究进展

本文对国内外钙钛矿锰氧化物电荷有序体系中自旋玻璃行为的研究现状进行了分析,对通过B位掺杂和外加磁场来研究自旋玻璃行为的新方案提出了初步设想。

帕金森病大鼠行为学与黑质形态学变化的相关性研究

目的 观察帕金森病 (PD)大鼠行为学及其形态学特点。方法 通过 PD大鼠模型 ,采用行为学观察、TUNEL法、HE染色、Nissl染色、电镜方法 ,观察模型成功后 1 d、7d、1 4 d PD大鼠行为、形态学变化。结果 PD大鼠旋转圈数无明显变化 ,凋亡细胞、尼氏细胞逐渐减少 ,超微结构损伤逐渐加重。结论 PD大鼠旋转行为变化是有其病理学基础的。

La(0.3)Ca(0.7)Mn(1–x)VxO3体系的电荷序和自旋序(英文)

通过对样品La0.3Ca0.7Mn1–xVxO3(x=0.05,0.10,0.134,0.20)的磁化强度–温度(magnetization–temperature,M–T)曲线、电阻率–温度(resistivity–temperature,ρ–T)曲线、电子自旋共振谱的测量,研究了Mn位V掺杂对La0.3Ca0.7MnO3体系电荷序和自旋序的影响。结果表明:当0.05≤x≤0.134时,体系存在电荷有序(CO)相,体系自旋序随温度降低发生顺磁(paramagnetism,PM)–电荷有序(charge ordering,CO)–反铁磁(antiferromagnetism,AFM)变化。当x=0.20时,电荷有序融化,体系出现再入型自旋玻璃行为。

旋量玻色—爱因斯坦凝聚体平均自旋在外场中的演化

利用平均场理论和单空间模近似,研究了总自旋F=1的旋量玻色—爱因斯坦凝聚体的平均自旋在外磁场的演化行为.理论研究结果表明平均自旋演化行为与对称相互作用无关;当处于不同量子态的粒子数不随时间变化时,体系自旋的行为由外磁场、反对称相互作用决定.

La_(0.3)Ca_(0.7)Mn_(1-x)V_xO_3体系的有序相和再入型自旋玻璃行为研究

通过对La0.3Ca0.7Mn1-xVxO3(x=0.05,0.10,0.134,0.20)体系的M-T曲线、ρ-T曲线、ESR谱的测量,研究了Mn位掺V对La0.3Ca0.7MnO3体系电荷序和自旋序的影响.结果表明,当0.05≤x≤0.134时,体系存在电荷有序(CO)相,其自旋序随温度降低发生顺磁(PM)-电荷有序(CO)-反铁磁(AFM)变化.当x=0.20时,CO相逐步融化,在40K发生自旋玻璃转变,表现出再入型的自旋玻璃行为,低温下的基态存在着多种复杂的磁相互作用之间的竞争机理.

Corrosion behavior of T2 copper in 3.5% sodium chloride solution treated by rotating electromagnetic field

Copper is susceptible to producing corrosion problems in corrosive environments, which leads to serious safety problems. Thus, investigating the corrosion behavior of copper is of great significance. The effects of rotating electromagnetic field on corrosion behavior of T2 copper in 3.5% sodium chloride solution with electrochemical measurements were investigated. The results showed that rotating electromagnetic field changed properties of 3.5% sodium chloride solution by increasing the values of temperature and pH and decreasing the values of conductivity and dissolved oxygen. The rotating electromagnetic field improved the corrosion resistance of T2 copper. The corrosion products of T2 copper in treated 3.5% sodium chloride solution were composed of Cu20 and CuCl. The low corrosion rate of T2 copper was resulted from the decrease of dissolved oxygen in 3.5% sodium chloride solution treated by rotating electromagnetic field.

Size dependent flow behaviors of particles in hydrocyclone based on multiphase simulation

To investigate the flow behaviors of different size particles in hydrocyclone,a designed process was numerically simulated by the transient solver,where the quartz particles possessing a size distribution were injected into a 100 mm diameter hydrocyclone with the steady water field and air core inside.A lab experimental work has validated the chosen models in simulation by comparing the classification efficiency results.The simulated process shows that the 25 μm quartz particles,close to the cut size,need much more time than the finer and coarser particles to reach the steady flow rate on the outlets of hydrocyclone.For the particles in the inner swirl,with the quartz size increasing from 5 to 25 μm,the particles take more time to enter the vortex finder.The 25 μm quartz particles move outward in the radial direction when they go up to the vortex finder,which is contrary to the quartz particles of 5 μm and 15 μm as they are closely surrounding the air core.The studies reveal that the flow behaviors of particles inside the hydrocyclone depend on the particle size.

La_(0.3)Ca_(0.7)Mn_(1-x)V_xO_3体系的有序相研究

通过对La0.3Ca0.7Mn1-xVxO3(x=0.05,0.10,0.134,0.20)体系的磁化强度-温度曲线(M-T)曲线、电阻率-温度曲线(ρ-T)的测量,研究了Mn位掺V对La0.3Ca0.7MnO3体系电荷序和自旋序的影响。结果表明:当0.05≤x≤0.134时,体系存在电荷有序(CO)相,其自旋序随温度降低发生顺磁(PM)-电荷有序(CO)-反铁磁(AFM)变化。当x=0.20时,CO相逐步融化,在40K发生自旋玻璃转变,表现出再入型的自旋玻璃行为,低温下的基态存在着多种复杂的磁相互作用之间的竞争机制。

Cross-sectional distortion behaviors of thin-walled rectangular tube in rotary-draw bending process

The cross-sectional distortion usually appears during rotary-draw bending process of thin-walled rectangular tube with small bending radius.To study the cross-sectional distortion of the tube,a three-dimensional finite-element model of the process was developed based on ABAQUS/Explicit code and its reliability was validated by experiment.Then,the cross-sectional distortion behaviors of the tube were investigated.The results show that a zone of larger circumferential stress appears on the tube when bending angle reaches 30°.And in the larger circumferential stress zone,the sagging phenomenon is produced obviously.The maximum cross-sectional distortion is located in the larger circumferential stress zone and the angle between the plane of maximum cross-sectional distortion and the bending reference plane is about 50°.The position of the maximum cross-sectional distortion keeps almost unchanged with the variation of the clearances between dies and tube.

Microscale deformation behavior of sandstone mineral particles based on XCT scanning

This work aimed to quantify the physical and mechanical behavior of three-dimensional microstructures in rocks under uniaxial compression.A high-precision in situ XCT(X-ray transmission computed tomography)technology was applied to investigating the behavior of mineral grains in sandstone:the movement,the rotation deformation,and the principal strains between fault zone and non-fault zone.The results indicate that after unloading,the shear strain of mineral grains is periodic in the radial direction,the strain of mineral grains in the fracture zone is about 30 times of the macro strain of the specimen,which is about 5 times in the non-fracture zone,and the shear strain near the fault zone is larger than the compressive strain,and there is the shear stress concentration feature.

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.

Deformation behaviour and microstructure evolution of AlMg6Mn alloy during shear spinning

Deformation behavior and microstructure of AlMg6Mn alloy subjected to shear spinning were studied by means of mechanical characterization, optical and SEM＋EDS microscopy. Specimens were shear spun on an industrial spinning machine using different mandrels, providing reductions of wall thickness of 30%, 50% and 68%. The grain structure developed during shear spinning refines gradually. The grains elongate in axial direction with increase of reduction, and also stretches along circumferencial direction. Optimal combination of strength and elongation is observed. This is attributed to grain refinement and dislocation reactions with particles and atoms of Mg and Mn in solid solution.

Plastic forming behavior of axisymmetric bimetal products with rotary swaging

In this paper,an elasto-viscoplastic three-dimension(3D) finite element model is developed to simulate the processing of bimetal tube with rotary swaging. Through simulation,the effects of high-frequency pulse stroking on the distribution and histories of stress,stain and loading are clarified. The stress in inner tube is compressive and higher than the minimum bonding force. Meanwhile,the stiffness of inner tube impacts outer tube extension in length.

Kinematic Viscosity and Shear Stress of Used Engine Oil

The goal of this paper describes kinematic viscosity and shear stress of two used engine oils, which have been taken from two different passenger cars. Kinematic viscosity and shear stress are two of the most important physical behaviours of fluids, especially lubricating fluids. In this paper the authors have focused on engine oil. Knowledge of these properties of engine oil is very important due to its lifetime. The experiments have been done using digital rotary rheometer Anton Paar DV-3 P with use of TR8 spindle and special adapter for a small amount of sample （20 mL）. Two different engine oils have been observed--first from passenger car Renault Scenic with petrol engine （engine capacity 1.6 dm3） and the second from passenger car Skoda Roomster with diesel engine （engine capacity 1.4 dm3）. Castrol Magnatec 10W-40 engine oil has been taken from Renault car and Shell Helix Ultra Extra 5W-30 engine oil has been taken from ~koda car. Service interval of change oil has been set to 15,000 km and samples of used engine oils have been taken after 1,500 km. Only first samples of used engine oils have been taken after raid of 20 km. All samples of used engine oils have been compared with new （unused） engine oils same specification. The measured values of kinematic viscosity and shear stress have been modeled using linear function. The coefficients of correlation R have been achieved high values （0.88-0.96）. The obtained models can be used to prediction of engine oil flow behaviour.

User Preference Survey on Staircase Rotation

Staircase is an important means of vertical transportation. Staircase design exerts a great influence on the aesthetics, transportation efficiency, user comfort and experience level. In this paper, a survey on the staircase rotation preference was conducted, based on the environment behavior studies. Different user frequencies of a pair of scissors stairs in the 2nd teaching building of North China University of Technology were analyzed. The psychological effect was evaluated and quantified, and the user preference on the two staircase rotations was then withdrawn. The survey found that the type of staircase with clockwise upstairs was much more preferred （78%） than the other staircase rotation anti-clock upstairs. Considering different genders, the female shows a 66% higher preference inclination of this type of staircase rotation than the male. To improve the transportation efficiency of the staircase in case of fire, the result of this paper can be very constructive for the evacuation staircase rotation choice for the high-rise buildings.

Biomechanical evaluation of an expansive pedicle screw in calf vertebrae

Objective: To obtain a comprehensive understanding of the effect of the improvement of fixation strength of a newly designed expansive pedicle screw through biomechanical analyses.Metheds: 100 (200 pedicles) fresh calf lumber vertebrae were used. A total of four instrumentation systems were tested including CDH (CD Horizon), USS (Universal Spine System pedicle screw), Tenor (Sofamor Denek) and expansive pedicle screw (EPS). Pullout and turning-back tests were performed to compare the holding strength of the expansive pedicle screw with conventional screws, i.e. USS, CDH and Tenor. Revision tests were performed to evaluate the mechanical properties of the expansive pedicle screw as a ”rescue” revision screw. A fatigue simulation using perpendicular load up to 1 500 000 cycles was carried out.Results: The turning back torque (Tmax) and pull-out force (Fmax) of EPS were significantly greater than those of USS, Tenor and CDH screws ( 6.5 mm×40 mm). In revision tests, the Fmax of both kinds of EPS ( 6.5 mm×40 mm; 7.0 mm×40 mm) were greater than that of CDH, USS and Tenor screws significantly (P< 0.05). No screws were broken or bent at the end of fatigue tests.Conclusions: EPS can significantly improve the bone purchase and the pull-out strength compared to USS, Tenor and CDH screws with similar dimensions before and after failure simulation. The fatigue characteristic of EPS is similar to that of CDH, USS and Tenor screws.

Unsteady Behavior of Surge and Rotating Stall in an Axial Flow Compressor

Unsteady behaviors as well as unsteady cascade flow fields of a single-stage axial flow compressor were experi- mentally investigated by detail measurements of unsteady performance characteristics and casing wall pressure and internal flow velocity fluctuations. The main feature of the test compressor is a capacity tank connected di- rectly to the compressor outlet in series through slits and a concentric duplex pipe, and also jet nozzles in order to inject compressed air toward the rotor tip region. Research attention is focused on the post-stall characteristics of surge and rotating stall which occur simultaneously. When the compressor was connected to the capacity tank, surge was generated with rotating stall in accordance with the capacitance increment of whole compressor system The surge behavior changed irregularly with throttling valve installed behind the compressor, and several types of surge cycles were observed. In addition, the surge cycle changed by jet injection to the rotor tip region. The re- suits suggested that the blockages of the cascade flow which were generated by a stall cell play an important role in deciding the surge behaviors.

Effects of power-law spectrum behaviors of nonthermal electrons on a ring-beam maser instability

The electron-cyclotron maser （ECM） emission driven by nonthermal electrons is one of the most crucial mechanisms responsible for radio emissions in magnetized planets, for the interplanetary medium （IPM） and for the laboratory microwave generation devices. Major astrophysical observations demonstrate that nonthermal electrons frequently have a negative power-law spectrum with a lower energy cutoff and anisotropic distribution in the velocity space. In this paper, the effects of power-law spectrum behaviors of electrons on a ring-beam maser emission are considered. The results show that the growth rates of O1 and X2 modes decrease rapidly for small A （the dispersion of momentum u）. Because of the lower energy cutoff behavior, the nonthermal electrons with large a still can excite the ECM instability efficiently. The present analysis also includes the effects of parameter β （βu0 is the dispersion of perpendicular momentum ui, u0 the average value of u） on the instability. The growth rate of X2 mode decreases with parameter v0 （v0 = u⊥o/uo, U⊥0 is the average value of u⊥）. But for O1 mode, the relationship between the growth rate and v0 is complicated. It also shows that the growth rates are very sensitive to frequency ratio Ω （frequency ratio of electron cyclotron frequency to plasma frequency）.

A study on dynamic beam-beam effects and their application in BEPCII

Beam-beam interactions cause dynamic behaviour of the charged particle beams in circular coUiders, which is directly related to their luminosity. The linear beam-beam force introduces an additional quadrupole that perturbs betatron motion of particles, including dynamic β, dynamic emittance and beam-beam tune-shifts; while the nonlinear force may excite resonances and cause tune-spread. With the weak-strong beam-beam mode, the linear and nonlinear effects are studied, dynamic βand dy- namic emittance as functions of tunes are analyzed, and formulas of beam-beam octupole caused tune-spread are derived, starting from beam-beam potential and equations of particle motions, and the measures to increase luminosity of BEPCII are discussed.