汽车用TWIP钢的力学性能与微观组织

采用热轧、冷轧及退火处理等工艺,对成分为25Mn-3Si-3Al的TWIP钢进行了试制,研究了钢板的力学性能、微观组织及其断裂机制,并采用X射线测定了钢板的晶体学织构.实验结果表明:钢板拉伸时发生典型的延性断裂;拉伸前的组织为伴有大量退火孪晶的奥氏体;在拉伸过程中退火孪晶转变成形变孪晶,使产品的强度和塑性提高;退火过程中形成的织构组分有利于塑性变形.     

布朗动力学理论模拟动态肌动蛋白纤维的增长

肌动蛋白的聚合耦合三磷酸腺酐(ATP)分子水解成二磷酸腺苷(ADP)分子和磷酸(Pi)的释放两个过程. 因此, 肌动蛋白纤维上的原聚体存在三种不同状态, 即分别结合ATP, ADP/Pi和ADP分子. 原聚体的不同状态导致纤维具有不同的空间图谱, 这些状态的空间分布将影响纤维的各种行为. 为此,建立了相应的分子模型,在布朗动力学模拟中实现了遵循时间演化的连续马尔可夫随机过程的解聚和水解反应; 重点阐述了如何实现纤维两端的聚合和解聚达到化学平衡的方法, 并系统研究了纤维在结合ATP分子的肌动蛋白单体溶液中的增长行为.     

一种基于人机交互的退火遗传算法

针对工程中存在的许多具有大规模、非线性、非凸等复杂特性的全局优化问题，在退火遗传算法的基础上，通过将人工方案和算法方案相结合，提出了一种基于人机交互的退火遗传算法，算法首先通过人机合作方式产生初始群体，并在随后的演化过程中，根据个体的适值自动地将人工个体从移民池中引入到算法群体中，引入的人工个体在同其他个体广泛交叉后，按Metropolis法则形成新群体，从而改善群体的质量并引导算法向更富希望的方向搜索，改进的自适应算子提高了算法的整体搜索能力，该算法具备演化算法的优点，并能发挥人的主动性，显示了求解复杂优化问题的应用潜力，算例的仿真结果验证了算法的有效性。     

基于混合优化算法的关节臂式测量机参数标定

为进一步提高关节臂式坐标测量机等高机动性精密测量设备的测量精度,使用D-H矩阵法建立其关节坐标转换数学模型并据此推导出参数误差模型.针对非线性多参数标定问题,通过变换分析消除了最小二乘法求解时矩阵中的冗余参数,降低了计算的复杂性.设定判定准则并实现最小二乘法和模拟退火算法的混合,提出了一种基于混合优化算法的参数标定方法,解决了LM算法的初值设定和SA算法的搜索效率逐步降低的问题.实验结果表明:关节臂式测量机参数经混合优化算法标定后,参数的误差范围有了显著的缩小,单点重复性误差的平均值减小了1.746 mm,长度误差的平均值减小了0.941 mm,测量误差得到了进一步的抑制.     

同时测定粮谷中痕量锰铁铜锌的人工神经网络辅助分光光度法

在pH 9.5时,Mn(Ⅱ )、 Fe(Ⅲ )、 Cu(Ⅱ )和 Zn(Ⅱ )均与 2-(5-溴-2-吡啶偶氮 )-5-二乙氨基苯酚和非离子表面活性剂聚乙二醇辛基苯基醚发生高灵敏的显色反应,生成稳定的三元胶束络合物 ,其λ max分别为 566、 560、 562和 559 nm,表明吸收光谱严重重叠 ; 在相应λ max处,其表观摩尔吸光系数分别为 1.13× 105、 7.32× 104、 1.02× 105和 1.04× 105 L· mol－ 1· cm－ 1。用模拟退火－误差反向传播人工神经网络辅助分光光度法,不经分离,同时测定了模拟样和粮谷样中的痕量锰、铁、铜和锌。详细研究了该算法的最佳计算条件。虽然体系的加和性较差,但由于该算法的优良性能,仍然取得了满意结果。     

Crystal polymorphs of 6‐[(phenylcarbamoyl)oxy]hexa‐2,4‐diyn‐1‐yl isonicotinate

The title compound, C₁₉H₁₄N₂O₄, was found to have two crystal polymorphs, in which the molecular structures of the diacetylenic compound are broadly similar. The main structural difference between the polymorphs concerns the intermolecular hydrogen‐bonding motifs adopted, namely a one‐dimensional zigzag polymer linked by N—H…N(py) (py is pyridine) interactions in polymorph I and a centrosymmetric dimeric motif formed by N—H…O=C interactions in polymorph II. The diacetylene cores of the molecules stack along the a and b axes in polymorphs I and II, respectively. It was found that only the molecular arrangement in polymorph II satisfies Baughman's criterion to afford polydiacetylenes (PDAs) by thermal annealing or irradiation with light. This predicted polymerization activity was confirmed by experiment.     

Self‐Assembly of Cylinder‐Forming ABA Triblock Copolymers under Cylindrical Confinement

The self‐assembly of two types of linear ABA triblock copolymers confined in cylindrical nanopores is studied using simulated annealing. The effects of pore size and block copolymer chain architecture on morphology, chain conformations and bridging fraction are investigated. For the bulk cylinder‐forming copolymers, novel structures such as helices and stacked toroids form, which depend sensitively on the pore size. Several significant differences between the two types of copolymers are predicted and explained based on the differences in their chain conformations and chain architectures. A simple model is proposed to explain the mean square radius of gyration for the bridge and loop chains.

     

Probing the early stages of thermal fractionation by successive self‐nucleation and annealing performed with fast scanning chip‐calorimetry

The thermal fractionation kinetics of a linear low‐density polyethylene (LLDPE) during Successive Self‐Nucleation and Annealing (SSA) is investigated by fast scanning chip‐calorimetry (FSC), by systematically varying the holding times (t_s) at each fractionation temperature (T_s). The range of explored fractionation times spans four orders of magnitude, from 0.001 to 10 s. Discernible thermal fractions are already detected in the very early stages of the process, at t_s shorter than one second. As t_s increases, the melting endotherm after SSA indicates a progressive lamellar thickening and narrowing of the thicknesses distribution of the various crystalline fractions. The largest variations are observed for the families of crystals containing the longest crystallizable sequences, which also undergo a change of their relative content as a consequence of self‐nucleated crystallization at T_s. The quality of the thermal fractionation obtained in 10 seconds with FSC is equivalent to that of conventional differential scanning calorimetry SSA (t_s = 300 s). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2200–2209     

A novel algorithm for chromatogram matching in qualitative analysis

The matching of the pattern of peaks produced during gas chromatography is of importance to many applications. At present, this task is generally performed manually, but this generates the usual problems associated with human inspection, such as a lack of objectivity and reproducibility, proneness to errors, and practical restriction of the volume of data which can reasonably be processed. This paper explores the use of a novel algorithm for automation of this task. The performance of the method on well controlled simulated data sets and real chromatograms is used to show not only how problems of manual inspection can be circumvented, but also how the existence of such a powerful method should open up the possibility of many new analyses for quality control, discrimination of varieties of sample, and the identification of specific components within a sample.