Overcoming challenges in the study of nitrided microalloyed steels using atom probe

Nitrided steels are widely used in the engineering field due to their superior hardness and other attractive properties. Atom probe tomography (APT) was employed to study two Nb-microalloyed CASTRIP steels with different N contents. A major challenge of using APT to study this group of materials is the presence of tails after Fe peaks in the mass spectra, which overestimates the composition for alloying elements such as Nb and Cu in the steels. One important factor that contributes to the tails is believed to be delayed field evaporation from Fe²⁺. This artefact of the mass spectrum was observed to be the most severe when voltage pulsing was used. The application of laser pulses with energy ranging from 0.2 to 1.2 nJ successfully reduced the tails and lead to better compositional measurement accuracy. Spatial resolution in the z-direction (along the tip direction) was observed to be less affected by changing laser energy but deteriorates in x-y direction with increasing laser energy. This investigation suggests that pulsed-laser atom probe with ∼0.4 nJ laser energy can be used to study this group of materials with improved mass resolution while still maintaining high spatial resolution.     

Value and limits of μ-CT for nondemineralized bone tissue processing

An experimental approach was performed on 20 giant rabbits to establish the possibilities and limitations of μ-CT for routine processing of nondemineralized bone tissue. Hydroxyapatite (HA) or β-tricalciumphosphate (β-TCP) bead implants or a melange of both, microchambered and solid, were implanted into a standardized and precise defect in the patellar groove. The bone-healing phase was chosen for the histology considering 1 or 2 days, and 2, 3, and 6 weeks. Normal X-ray and μ-CT were applied on all specimens; five specimens in the 6-week stage were additionally processed according to the full range of conventional nondemineralized bone processing methods. μ-CT increased the possibilities of nondemineralized histology with respect to bone morphometry and a complete sequence of sections, thus providing a complete analysis of the bone response. μ-CT was limited in differentiating bone quality, cell analyses, and mineralization stages. The investigation based on normal X-rays is limited to defining integration and excluding the fibrous and bony encapsulation of loose implants. μ-CT allows a 3D evaluation of newly formed bone which is clearly marked against the ceramic implant. It does not allow, however, for the differentiation between woven and lamellar bone, the presentation of the canalicular lacunar system, or on the cell level, revealing canaliculi or details of the mineralization process which can be documented by high-resolution microradiography. Titer dynamics of bone formation remains the domain of polychromatic sequential labeling. The complete sequence of μ-CT slices enhances the possibilities for routine histology, tremendously allowing to the focus on detail histology to topographically well-defined cuts, thus providing more precise conclusions which take into consideration the whole implant.     

基于感兴趣区域的可变频CCD实时处理系统

为满足航空摄影测量需求,设计了基于感兴趣区域的可变频CCD实时处理系统。该系统主要由CCD控制模块、数据实时处理模块和显示模块组成。系统充分利用FPGA内部资源,改变了传统FPGA配合微处理器的实现方式,相关算法和时序逻辑控制均在一片FPGA内实现并通过验证,可广泛适用于任何分辨率CCD的智能实时处理。     

Action diversity in a simulation of the Israeli-Palestinian conflict

This article explores the strategies used by Israeli students to resolve the Israeli-Palestinian conflict in the interactive computer game, PeaceMaker. Students played PeaceMaker in the roles of both the Israeli Prime Minister and the Palestinian President in random order. Students must take actions satisfying constituents on both sides of the conflict in order to win the game. The diversity of actions taken in each role was measured. Several hypotheses test the degree to which Israeli students, depending on which role they played and their own demographic variables, exploited a consistent set of actions or explored a more diverse range of actions across three main types: construction, political, and security. The results show that (1) greater action diversity increases success in both roles, (2) Israeli students engaged in less diverse actions when playing the Israeli role than when playing the Palestinian role, (3) students’ religiosity and political Hawkishness negatively predicted action diversity when playing the Palestinian role, and (4) action diversity mediates the relationship between a student’s background knowledge about the conflict and success in the Israeli role. The significance of these findings for understanding attitudes about the Israeli-Palestinian conflict are discussed, including implications for conflict resolution more generally.     

A supervisory loop approach to fulfill workspace constraints in redundant robots

An approach based on geometric invariance and sliding mode ideas is proposed for redundancy resolution in robotic systems to fulfill configuration and workspace constraints caused by robot mechanical limits, collision avoidance, industrial security, etc. Some interesting features of the proposal are that: (1) it can be interpreted as a limit case of the classical potential field-based approach for collision avoidance which requires using variable structure control concepts, (2) it allows reaching the limit surface of the constraints smoothly, depending on a free design parameter, and (3) it can be easily added as a supervisory block to pre-existing redundancy resolution schemes. The algorithm is evaluated in simulation on a 6R planar robot and on the freely accessible 6R robot model PUMA-560, for which the main features of the method are illustrated.     

一种数字阵列天气雷达信号处理系统设计

为了获得气象目标信息参数、为分析湍流等天气过程演变提供更精细的信息、为高质量气象分析提供更好的手段,结合研制的某X波段数字阵列天气雷达,对数字波束形成（DBF）技术、杂波抑制和频域解模糊等问题进行了分析和仿真;探讨了DBF技术在天气雷达中的应用优势,对因波束电扫描使波位变化导致回波信号跳跃而限制IIR滤波器和脉冲对处理（PPP）应用的问题,提出采用频域插补技术来实现地物杂波抑制和保证气象目标券数估计的盾量．最后．给出了天气雷达信号处理系统工程设计方案．     

手性樟脑磺酸的合成及表征

以樟脑粉为原料合成了消旋樟脑磺酸;采用l-苯甘氨酸为拆分剂,经拆分、纯化分离得到了手性樟脑磺酸。合成消旋樟脑磺酸的适宜工艺条件为：反应时间25 h,浓硫酸的滴加速度0.5～1.0 mL/min,反应温度10℃,消旋樟脑磺酸的收率85.6%,熔点195～201℃。拆分的适宜工艺条件为：物料比n（dl-樟脑磺酸）∶n（l-苯甘氨酸）=1∶0.95,d-樟脑磺酸拆分收率64%,熔点194～196℃,[α]2D0=＋23°（C=5,H2O）;l-樟脑磺酸拆分收率90.8%,熔点197～198℃,[α]2D0=-22.5°（C=5,H2O）。样品经熔点、旋光率、红外光谱等检测方法,证明与目标产物一致。     

基于CBERS-02B高分辨率遥感影像分割的最优尺度选取

高分辨遥感影像的信息提取对矿山的监测有着重要意义,影像分割是高分辨率遥感影像信息提取关键的一步．文中以赣州稀土矿山的高分辨率遥感影像为源数据,采用分形网络演化多尺度分割算法对高分辨率遥感影像进行分割,通过Robert算子的边缘提取结果计算分割参数获取分割尺度,并在此基础上设置不同分割尺度对影像进行分割,对比分析分割结果表明,沉淀池的最优分割尺度为35．最后利用分割质量值对分割结果进行评价分析,验证了试验结果的正确性．     

化学-酶法动态动力学拆分外消旋仲醇研究进展

介绍了外消旋仲醇动态动力学拆分的反应原理及金属配合物、酸性沸石催化仲醇消旋化反应的机理,论述了近年来过渡金属配合物催化剂、酸性催化剂与固定化脂肪酶结合,进行仲醇动态动力学拆分反应的研究进展。     

有限责任公司股东会决议效力分析——以对外担保为视角

股东大会是公司的最高权力机构,依法作出的股东会决议具有法律效力,但股东会作出的决议应当做到程序合法、内容合法并符合公司章程规定,否则就可能会影响股东会决议的效力。对外担保是公司一项重要的非常规经营,应由股东会行使担保的决策权,但若股东会决议存在瑕疵则会影响股东权益、债权人利益以及社会经济的稳定。本文拟以对外担保的股东会决议瑕疵为切入点,探讨公司股东会决议的效力问题。