Investigation of magnetization reversal and domain structures in perpendicular synthetic antiferromagnets by first-order reversal curves and magneto-optical Kerr effect

Perpendicular synthetic-antiferromagnet(p-SAF) has broad applications in spin-transfer-torque magnetic random access memory and magnetic sensors. In this study, the p-SAF films consisting of (Co/Ni)3]/Ir(tIr)/[(Ni/Co)3are fabricated by magnetron sputtering technology. We study the domain structure and switching field distribution in p-SAF by changing the thickness of the infrared space layer. The strongest exchange coupling field(Hex) is observed when the thickness of Ir layer(tIr) is 0.7 nm and becoming weak according to the Ruderman–Kittel–Kasuya–Yosida-type coupling at 1.05 nm,2.1 nm, 4.55 nm, and 4.9 nm in sequence. Furthermore, the domain switching process between the upper Co/Ni stack and the bottom Co/Ni stack is different because of the antiferromagnet coupling. Compared with ferromagnet coupling films, the antiferromagnet samples possess three irreversible reversal regions in the first-order reversal curve distribution.With tIrincreasing, these irreversible reversal regions become denser and smaller. The results from this study will help us understand the details of the magnetization reversal process in the p-SAF.

Minimum Roadside Clearance Offsets on the Inside of Reverse Curves Based on Flat Spirals

Design guidelines require that high objects on the inside of horizontal curves be cleared so as to provide sufficient sight distance. An example of the guidelines that require such clearance is the AASHTO’s Green Book. The Green Book has an analytical model for determining minimum clearance for a given design sight distance. The model is well suited for middle sections of long curves. Applying such clearance to sections near beginnings and ends of the curves and to sections where there is reverse of curvature will result in over-clearance. Over-clearance implies extra cost of earthwork where highways pass in cut zones. To avoid such extra costs the guideline suggests using the graphical method to determine exact clearance offsets. The graphical method is accurate but it is also tedious and time consuming. This study developed analytical models for efficiently determining clearance offsets that match the offsets determined with the graphical method. The offsets are ordinates from driver paths to flat roadside spirals that make the boundary of the roadside area to clear. Mathematical equations for the spirals comprise of terms related to highway speed (in the form of design sight distance), curve features, and driver locations. In turn, these terms define magnitudes of the offsets to the spirals. Combination of the terms results in many parameters to the extent of making difficult development of design charts for offsets. However, examining suitability of published offset charts for simple curves as estimates of offsets for sites with reverse curves leads to finding that the charts are suitable as long as the reverse curves have common tangents that are at least as long as 25% of design sight distance. For reverse curves with no common tangents, offset charts have been developed and presented in this paper. Practitioners can use these charts or the derived equations to determine clearance offsets for new sites as well as for existing sites that are deficient in design sight distance.

Discussion on Reverse Design of Components with Complex Curved Surface and Computer Numerical Control Machining

With the continuous development and advancement of science and technology,the work of tool path planning has received extensive attention.Among them,curved surface generation and data processing are the focus of management and design,which necessitate the full application of reverse design of complex curved surface components to complete numerical control processing,effective optimization and upgrading,integration the tasks of point cloud data collection,and point cloud data processing to ensure that the corresponding computer numerical control machining model can exert its actual value.This paper briefly analyzes the basic principles of curved surface reconstruction as well as discusses the reverse design of complex curved components and the experimental processes and results that involved computer numerical control machining,which serves the purpose as reference only.

Discrete Methods Based on First Order Reversal Curves to Identify Preisach Model of Smart Materials

Preisach model is widely used in modeling of smart materials. Although first order reversal curves （FORCs） have often found applications in the fields of physics and geology, they are able to serve to identify Preisach model. In order to clarify the relationship between the Preisach model and the first order reversal curves, this paper is directed towards： （1） giving the reason a first order reversal curve is introduced; （2） presenting, for identifying Preisach model, two discrete methods, which are analytically based on first order reversal curves. Herein also is indicated the solution＇s uniqueness of these two identifying methods. At last, the validity of these two methods is verified by simulating a real smart actuator both methods have been applied to.

First-order reversal curves of magnetic recording tapes

The interaction and its variation between magnetic grains in two kinds of magnetic recording tapes are investigated by first-order reversal curves （FORC） and the 5M method. The composition and microstructure of the samples are characterised by x-ray diffraction and scanning electron microscope. The FORC diagram can provide more accurate information of the interaction and its variation, but the 5M curves cannot. The positive interaction field and the large variation of the interaction field have opposite effects on the δM curve.

Investigations on if-E Curve in Cyclic Derivative Chronopotentiometry(Ⅵ)——Theoretical Equations of if-E Curves in the Case of Quasi-reversible and Irreversible Electrode Reactions

The theory of if-E curve in cyclic derivative chronopotentiometry is presented. Theoretical equations of if-E curves in the case of quasi-reversible and irreversible electrode reactions are deduced respectively.

Reversed ethane/ethylene adsorption in a metal–organic framework via introduction of oxygen

Separation of ethane from ethylene is a very important but challenging process in the petrochemical industry.Finding an alternative method would reduce the energy needed to make 170 million tons of ethylene manufactured worldwide each year.Adsorptive separation using C2H6-selective porous materials to directly produce high-purity C2H4 is more energy-efficient.We herein report the"reversed C2H6/C2H4 adsorption"in a metal–organic framework Cr-BTC via the introduction of oxygen on its open metal sites.The oxidized Cr-BTC(O2)can bind C2H6 over C2H4 through the active Cr-superoxo sites,which was elucidated by the gas sorption isotherms and density functional theory calculations.This material thus exhibits a good performance for the separation of 50/50 C2H6/C2H4 mixtures to produce 99.99%pure C2H4 in a single separation operation.

Study on Project Progress Curve Model

Because of the discrepancy of project types,the project progress curves present different characteristics.Studying project progress curves can reduce management risk of project and overall grasp the enforcement condition of the project.Combining project characteristic,this paper reaches 4 kinds of project progress curve patterns.If the front of the progress curve is concave,and its rear is protruding in the break point,it is named as S model.If its front is protruding and its rear is concave in the break point,it is named as the reverse side of S model.If the front and rear are concave in the break point,it is named as J model,and two half sections are both upward protruding,it is named as the reverse side of J model.Through a case study,it shows that application project progress curve model can better raise project management.

基于逆向重布线改进RRT-Connect算法的机械臂路径规划

为解决RRT-Connect算法在复杂非结构环境下规划出的路径成本较长、有效节点数过多、曲折不平滑等问题,提出了一种基于逆向重布线的改进RRT-Connect算法(Improved-RRT-Connect).首先,在算法的起始位置加入碰撞检测函数,当起点和终点之间不存在障碍物时,能够快速生成一条路径;其次,通过对生成的路径采取逆向重布线的措施,对生成的路径中的节点进行重新筛选布线,达到缩短生成路径长度,减少有效节点数量的目的;最后,通过结合B样条曲线对生成的路径进行拟合处理,得到一条平滑连续的路径.通过Improved-RRT-Connect算法与RRT、RRT^(*)-Smart、RRT-Connect等算法的对比实验表明,在规划时间上,Improved-RRT-Connect算法比RRT、RRT^(*)-Smart算法减少了52.14%、98.53%,在路径成本上比RRT、RRT-Connect算法减少了19.39%、17.15%,阐明了提出的Improved-RRT-Connect算法的优越性.

光伏组件单二极管模型的新型曲线拟合算法

针对光伏组件单二极管模型的非线性隐式超越方程特性,提出了一种改进的曲线拟合算法,通过调整模型中二极管反向饱和电流的求解形式,并应用高斯-牛顿法进行参数迭代,有效提升了模型的仿真精度和计算速度。通过与经典算例的结果对比分析,验证了所提出的算法在提高仿真精度和改善收敛性方面的显著优势,为光伏发电系统设计和性能评估提供了有力的技术支持。

重载铁路反向曲线区段行车安全分析

重载铁路是国内外货运发展的主流方向,目前我国部分重载线路存在空、重载荷列车共行的单线铁路。本文基于某既有空、重载荷列车共行单线铁路实际运营条件,对共行线长大坡道上反向曲线区段空、重载荷列车条件下,行车安全性进行论证和分析,为工程应用提供理论支撑和安全评价。结果表明:在重载工况条件下,列车以100 km/h速度通过该长大坡道反向曲线,在空载工况时,列车应在该反向曲线区段限速80 km/h;通过对该反向曲线区段行车性能分析研究,在重载铁路新线设计中重车方向缓和曲线长度可采用《重载铁路设计规范》中相关规定,空车方向600 m小曲线半径连接缓和曲线长度建议:取值大于80 m。

曲面构件阵列超声频域逆时偏移成像方法研究

曲面构件因其独特的结构和力学特性,广泛应用于航空航天领域。然而,未知的曲面形状导致阵列超声检测时,声传播延时计算不准确,影响缺陷检测的精度。为解决这一问题,提出了一种不依赖声传播延时的适用于曲面构件的阵列超声频域逆时偏移成像方法。首先,利用阵列超声全聚焦方法对曲面构件表面进行成像;然后,对成像结果进行阈值分割和曲线拟合,重构构件表面形状并建立二维声学特性分布模型;最后,通过频域逆时偏移将来自超声波源的正向传播波场与缺陷反射体的反向传播波场进行互相关成像。实验结果表明,所提出的方法可以有效实现曲面构件内部缺陷成像,与传统的阵列超声全聚焦方法相比,缺陷的成像质量提升66%以上,缺陷定量平均误差降低37.04%以上。

基于暗特性曲线提取辐伏转换器件特性参数的算法

开展辐伏电池理论研究需要计算辐伏转换器件的特性参数,通过特性参数即可预测辐照条件下辐伏转换器件的输出特性,为辐伏电池设计提供重要理论参考。本研究算法基于辐伏转换器件暗特性曲线,计算辐伏转换器件的特性参数,并通过统计学方法分析计算特性参数的优劣。并利用提取出的特性参数预测转换器件在源辐照条件下的特性曲线并与实际测量的辐照特性曲线对比,以证明算法的有效性。结果表明,计算结果在曲线拟合和输出特性预测上均取得了良好的效果。此算法能够在不辐照器件的基础上,通过暗特性曲线预测电池输出特性,可为辐伏电池的设计提供指导。

磁场角度对人工反铁磁体磁反转的影响

研究了具有垂直磁各向异性人工反铁磁的磁反转,人工反铁磁的四种稳定磁态由层间磁矩的相互排列决定,并受层间交换相互作用和塞曼能的控制。测量了人工反铁磁不同磁场角度的磁滞回线,磁场从易轴方向变化到难轴方向,低场反铁磁耦合平台逐渐向高场倾斜,翻转场和饱和场增高。最后,采用一阶反转曲线分析方法,分析了外磁场角度变化对人工反铁磁中磁反转的影响。

基于逆向工程技术的消旋卡多曲散制备工艺研究

目的基于逆向工程技术对消旋卡多曲散原研解析,开发与参比制剂具有质量一致性的消旋卡多曲散剂,并探讨针对散剂或颗粒剂的逆向解析思路。方法首先,通过原研专利、说明书等文献信息分析,初步了解产品处方组成和制备工艺;其次,针对散剂剂型特征,分别对不同筛分目数下的样品性状、粒度分布、含量分布、溶出特征等进行测定,了解原研制剂的质量属性特征;最后,基于原研逆向解析结果,分别对制粒、整粒及混合工艺进行考察研究,确认相关工艺参数对产品关键质量属性的影响趋势,并进行连续中试放大研究。结果原研制剂主要通过将部分物料进行“致密”制粒后进行整粒,获得部分具有较快溶出的细粉状物和部分溶出较慢的大颗粒物,从而使原研体外溶出呈现双相溶出特征;进一步地通过对本品制粒、整粒及混合工艺的考察及放大确认,开发出了与原研体外溶出特征及粒度分布等质量一致的消旋卡多曲散,且工艺稳定可行。结论本研究基于对固体颗粒剂或散剂的逆向工程技术手段,成功且高效地开发出了与原研体外溶出行为和主要制剂学表征指标一致的产品,为该类剂型的研发提供了参考思路。

基桩承载力反向自平衡试桩法模型试验研究

针对反向自平衡试桩法在工程实践中可能存在的问题,应用室内模型试验对该方法的可操作性进行研究。首先,设计并浇筑完成了反向自平衡试桩法模型试验装置;其次,分别进行桩身加载和桩顶加载试验,得到试验数据;最后,将试验结果和经验公式法计算结果进行对比分析。研究结果表明:反向自平衡试桩法荷载箱位置难以同时满足两次加载所需平衡力的要求,且结果还受加载顺序和上下段桩之间预留间距影响,还需对最优加载顺序确定、荷载补偿、上下段桩间预留距离确定等问题进行研究。

Innovative roadside design curve of lateral clearance： Roadway reverse horizontal curves

This paper presents a proposed concept of a spiraled roadside curve for determining the required lateral clearance that satisfies sight distance needs on a roadway reverse hori- zontal curve. The spiraled roadside curve was evaluated in the context of roadway plan view. The characteristics of its corresponding lateral offsets were analyzed. It was found that the ratio of the radii for the two reversing circular curves was the major factor that impacted the ratio of the required offset to the maximum offset of a circular curve. A single design chart and a design table were developed. The required offsets at alignment reversing sections were far less than those recommended by the American Association of State Highways and Transportation Officials （AASHTO） and those required at the approach and departure sections of a roadway simple curve. At the common point of the two reversing circular curves having a radius ratio R2/R1 ranging from 0.5 to 2, the required offsets were approximately 34%-66% of the maximum offsets recommended by AASHTO and approximately 41%-79% of those required in the case of a simple curve. The engi- neering implications of the proposed spiraled roadside curve are multifold： （a） it can be designed in a way similar to traditional roadway design, （b） it avoided the application of numerous design charts and extensive computations, （c） it can be easily staked on the field, （d） it not only greatly improved the A_ASHTO approximate approach, but also improved roadway design consistency.

Impact of surgical volume and resident involvement on patency rates after vasectomy reversaldA 14-year experience in an open access system

Objective:Evaluate the influence of fellowship training,resident participation,reconstruction type,and patient factors on outcomes after vasectomy reversals in a high volume,open access system.Methods:Retrospective review of all vasectomy reversals performed at a single institution from January 1,2002 to December 31,2016 was conducted.Patient and spouse demographics,patient tobacco use and comorbidities,surgeon training and case volume,resident participation,reconstruction type,and postoperative patency were collected and analyzed.Results:Five hundred and twenty-six vasectomy reversals were performed during the study period.Follow-up was available in 80.6%of the cohort and overall patency,regardless of reconstruction type was 88.7%.The mean time to reversal was 7.87 years(range of 0-34 years).The majority of cases included resident participation.Case volume was high with faculty and residents logging a mean of 37.0 and 38.7(median 18 and 37)cases respectively.Bilateral vasovasostomy was the most common reconstruction type(83%)and demonstrated a significantly better patency rate(89%)than all other reconstructions(p=0.0008).Overall patency and patency by reconstruction type were not statistically different among faculty surgeons and were not impacted by fertility fellowship training,resident participation or postgraduate year.Multivariate analysis demonstrated that increased time to reversal and repeat reconstructions had a negative impact on patency(p=0.0023 and p=0.043,respectively).Conclusions:Surgeons with a high volume of vasectomy reversals have outcomes consistent with contemporary series regardless of fellowship training in fertility.Patency was better for bilateral vasovasostomies.Patency was not negatively impacted by tobacco use,comorbidities,resident participation,or post-graduate year.

NURBS曲面逆节点插入法

针对工程中对控制点的特殊需求,提出了一种非均匀有理B样条曲面逆节点插入方法。从分析NURBS控制多边形的边及其相关联的节点出发,通过齐次坐标投影确定必须插入节点所在区间,利用插入控制点对控制多边形的边分割与需插入节点对参数区间的分割等比例映射,获得过任意点并与控制多边形对边相交的等参线,得到对应插入节点,再从插入节点出发反方向确定所有需要插入的控制点,协同实现某特殊需求控制点插入的任务。数值算例验证了文中方法对于NURBS曲面插入控制点的有效性,且具有明显的几何和物理意义。

矩形-八边形组合螺旋箍筋柱抗震性能分析

为研究矩形-八边形组合螺旋箍筋混凝土柱的抗震性能,本文对其(RCC1、RCC4)以及手工绑扎矩形箍筋柱(RCC2、RCC5)、井字形箍筋(RCC3、RCC6)柱开展了0.2、0.8轴压比下足尺低周反复荷载试验研究。结果表明:3种不同箍筋形式的混凝土柱在0.2和0.8轴压比下分别以大偏心压弯破坏、小偏心压弯破坏为标志;在0.2和0.8轴压比下的滞回曲线均较为饱满且在相同轴压比下的耗能基本一致。0.2轴压比下,RCC1的承载力分别比RCC2、RCC3的承载力高2.5%和3.7%,RCC1的位移延性分别比RCC2、RCC3的位移延性高4.6%和2.3%;0.8轴压比下,RCC4的承载力分别比RCC5、RCC6的承载力高4.6%和6.65%,RCC4的位移延性分别比RCC5、RCC6的位移延性高9.5%和4.2%。