Five-parameter crystallographic characteristics of the interfaces formed during ferrite to austenite transformation in a duplex stainless steel

The crystallography of interfaces in a duplex stainless steel having an equiaxed microstructure produced through the ferrite to austenite diffusive phase transformation has been studied. The five-parameter interface character distribution revealed a high anisotropy in habit planes for the austenite–ferrite and austenite–austenite interfaces for different lattice misorientations. The austenite and ferrite habit planes largely terminated on (1 1 1) and (1 1 0) planes, respectively, for the austenite–ferrite interfaces associated with Kurdjumov–Sachs (K–S) and Nishiyama–Wasserman (N–W) orientation relationships. This was mostly attributed to the crystallographic preference associated with the phase transformation. For the austenite–ferrite interfaces with orientation relationships which are neither K–S nor N–W, both austenite and ferrite habit planes had (1 1 1) orientations. Σ3 twin boundaries comprised the majority of austenite–austenite interfaces, mostly showing a pure twist character and terminating on (1 1 1) planes due to the minimum energy configuration. The second highest populated austenite–austenite boundary was Σ9, which tended to have grain boundary planes in the tilt zone due to the geometrical constraints. Furthermore, the intervariant crystallographic plane distribution associated with the K–S orientation relationship displayed a general tendency for the austenite habit planes to terminate with the (1 1 1) orientation, mainly due to the crystallographic preference associated with the phase transformation.     

一种基于速度强度熵VMME与纹理特征的人群异常检测算法

人群异常事件检测是智能视频监控领域的重要研究内容, 文章提出了一种融合速度强度熵VMME与纹理特征的人群异常行为检测算法. 该算法采用LBPCM算法提取图像纹理特征, 在视频帧计算光流基础上, 获得特征点速度强度图, 并以其熵VMME作为场景运动特征, 将场景纹理特征和运动特征送入支持向量机训练分类. 实验表明, 新算法可实现对人群异常行为的检测, 且有较高准确率.     

The ground states and pseudospin textures of rotating two-component Bose–Einstein condensates trapped in harmonic plus quartic potential

The ground states of two-component miscible Bose–Einstein condensates(BECs) confined in a rotating annular trap are obtained by using the Thomas–Fermi(TF) approximation method.The ground state density distribution of the condensates experiences a transition from a disc shape to an annulus shape either when the angular frequency increases and the width and the center height of the trap are fixed,or when the width and the center height of the trap increase and the angular frequency is fixed.Meantime the numerical solutions of the ground states of the trapped two-component miscible BECs with the same condition are obtained by using imaginary-time propagation method.They are in good agreement with the solutions obtained by the TF approximation method.The ground states of the trapped two-component immiscible BECs are also given by using the imaginary-time propagation method.Furthermore,by introducing a normalized complex-valued spinor,three kinds of pseudospin textures of the BECs,i.e.,giant skyrmion,coaxial double-annulus skyrmion,and coaxial three-annulus skyrmion,are found.     

基于GPU加速的几何纹理合成方法

提出了一种基于GPU加速的几何纹理合成方法,以解决几何纹理合成过程中高计算量、高存储占用和高耗时等问题.首先,对样本几何纹理数据进行子块划分,并根据子块在样本中的位置关系设计可重用样本顶点数据的数据结构,优化存储以降低内存的占用率;然后,采用GPU多线程并发技术设计并行加速算法,将串行的几何纹理合成过程并行化,从而实现快速生成任意尺寸的新的几何纹理.实验结果表明,该算法不仅占用存储较少,而且在保证合成质量的同时极大地降低了几何纹理的合成耗时.     

激光表面织构对不同材料干摩擦特性的影响

采用环-块线接触摩擦磨损试验,研究了经激光处理后不同织构面密度的45钢和12Cr凹坑形织构试件的干摩擦磨损特性.借助高精度天平分析了试件磨损量,采用三维形貌仪和扫描电镜对试件表面形貌进行了分析.研究结果表明:激光表面织构化使得45钢试件表面形成可以改善摩擦性能的高硬度质点;在相同试验条件下,与无织构试件相比,45钢织构环试件磨损量明显降低,而12Cr织构环试件磨损量却有所升高;织构试件的磨损量在一定范围内随着织构面密度的增加而降低;激光织构化对摩擦系数的稳定值影响不大.     

Structure and magnetic properties of γ′-Fe4N films grown on MgO-buffered Si (0 0 1)

γ′-Fe₄N thin films were grown on MgO-buffered Si (1 0 0) by pulsed laser deposition technique. Different crystallographic orientations and in-plane magnetic anisotropies were achieved by varying the growth temperature of the MgO buffer layer. When the MgO buffer layer was grown at room temperature, the γ′-Fe₄N film shows isotropic in-plane magnetic properties without obvious texture; while in-plane magnetic anisotropy was recorded for the γ′-Fe₄N films deposited on a 600 °C-grown-MgO buffer due to the formation of a (1 0 0)-oriented biaxial texture. Such a difference in in-plane magnetic anisotropy is attributed to the epitaxial growth of γ′-Fe₄N film on an MgO buffer with relaxed strain when the MgO layer was grown at a high temperature of 600 °C.     

烟气脱硫活性炭微波再生特性的实验研究

研究了烟气脱硫活性炭的微波再生特性。通过扫描电镜、N₂吸附、元素分析、Boehm滴定表征微波再生对活性炭孔隙结构和表面化学性质的影响,分析微波再生对活性炭吸附烟气中SO₂的影响规律。结果表明,微波再生功率越高,SO₂再生曲线越窄,峰值浓度越高,有利于载硫活性炭的解吸和高浓度再生气的获取。微波再生对活性炭起到了活化作用,使活性炭的孔结构变狭长。随着微波再生功率的提高,活性炭的微孔比表面积、微孔孔容增加,酸性官能团含量上升,碱性官能团含量下降。100 W再生后,活性炭再生不完全,残留的H₂SO₄影响了活性炭的吸附,活性炭的SO₂吸附性能下降。200、300、400 W工况下,活性炭的SO₂吸附容量均得到提高,且随着再生功率的提高,活性炭的碱性官能团含量上升,微孔比表面积、微孔孔容增加,SO₂吸附性能逐渐增强。     

碎裂结构边坡变形机理及治理对策研究

碎裂结构边坡稳定性受多组相交结构面控制,且受降雨、地震等多因素影响强烈,具有一定的特殊性。本文以某花岗岩碎裂结构边坡为例,在边坡的地质条件和岩体结构研究的基础上,结合施工及监测反馈信息,深入分析了边坡变形破坏模式,并根据稳定性计算结果,提出锚索、钢筋桩与排水相结合的支护方案。研究结果表明：坡体内部陡倾卸荷裂缝发育形成后缘切割面,中下部滑面追踪陡缓两组结构面发展;支护措施实施后,边坡经历“5•12”地震及雨季,多点位移计监测结果表明,地震和降雨对边坡稳定性影响较大,支护措施较好地控制了边坡变形。     

土壤质地分类的近红外光谱分析方法研究

依据所收集的25种土样,采用两种不同精度仪器、三种光谱方法以及3个不同谱区,在四种分类标准条件下进行土壤质地分类分析方法研究。结果表明：(1)土壤化学组成的信息主要体现在近红外光谱的谱峰特征,而质地等物理信息主要反映在光谱的斜率、截距参数上,且二者在不同谱区的相对强度不同;(2)近红外光谱方法对土壤质地的分辨能力较低,随着分类粗化而有所提高;(3)在4组分类标准中土壤质地最高预测准确度为72％,其中在砂粒<70％和粘粒<40％条件下,预测准确度达到85％;(4)样本顶部漫反射光谱方法与扩展谱区范围均可有效提高质地预测准确度,而高精度仪器并不具备明显优势。     

Shear-induced ordering of lamellar and gyroid structures observed in a nonionic surfactant/water system

The shear-induced ordering of lamellar and gyroid structures of a nonionic surfactant C₁₆E₇/D₂O system in a Couette shear cell ( 0.001 < < 10 s^-1, : shear rate) has been investigated by using a small angle neutron scattering technique. In the lamellar phase, the steady shear flow having > 0.01 s^-1 suppresses undulation fluctuations of lamellae (Maxwell effect). This suppression of fluctuations brings two effects; 1) shear-induced lamellae ordering toward a parallel orientation and 2) obstruction of a lamellar↦gyroid transition. It is quite interesting to note that there is a characteristic shear rate range ( 0.01 < < 0.3 s^-1), where both effects take place. We have also investigated the shear effects on the gyroid phase. Below the characteristic shear rate range, the gyroid structure keeps three-dimensional network lattice, while above the characteristic shear rate range, the gyroid structure transforms to the parallel orientation lamellae (shear-induced gyroid-lamellar transition). Thus the shear flow having the characteristic shear rate plays very important roles in shear ordering phenomena. Received 26 June 2000 and Received in final form 12 January 2001