管路-船体耦合振动及水下声辐射研究

充液管路广泛的应用于船舶冷却、输水等多个系统,其振动与水下声辐射一直是学术与工程中的研究热点。基于阻抗综合法,利用耦合点处力与位移的连续边界条件,采用管路解析公式、船体有限元数值计算、管路支撑测试数据三者相结合的方法对管路-船体耦合系统进行振动与水下声辐射工程预报。该综合方法被应用于一个复杂空间管路-船体耦合模型,并与有限元模型结果对比验证了该方法的正确性。     

Understanding the Structure and Properties of Sesqui‐Chalcogenides (i.e., V2VI3 or Pn2Ch3 (Pn = Pnictogen,Ch = Chalcogen) Compounds) from a Bonding Perspective

A number of sesqui‐chalcogenides show remarkable properties, which make them attractive for applications as thermoelectrics, topological insulators, and phase‐change materials. To see if these properties can be related to a special bonding mechanism, seven sesqui‐chalcogenides (Bi₂Te₃, Bi₂Se₃, Bi₂S₃, Sb₂Te₃, Sb₂Se₃, Sb₂S₃, and β‐As₂Te₃) and GaSe are investigated. Atom probe tomography studies reveal that four of the seven sesqui‐chalcogenides (Bi₂Te₃, Bi₂Se₃, Sb₂Te₃, and β‐As₂Te₃) show an unconventional bond‐breaking mechanism. The same four compounds evidence a remarkable property portfolio in density functional theory calculations including large Born effective charges, high optical dielectric constants, low Debye temperatures and an almost metal‐like electrical conductivity. These results are indicative for unconventional bonding leading to physical properties distinctively different from those caused by covalent, metallic, or ionic bonding. The experiments reveal that this bonding mechanism prevails in four sesqui‐chalcogenides, characterized by rather short interlayer distances at the van der Waals like gaps, suggestive of significant interlayer coupling. These conclusions are further supported by a subsequent quantum‐chemistry‐based bonding analysis employing charge partitioning, which reveals that the four sesqui‐chalcogenides with unconventional properties are characterized by modest levels of charge transfer and sharing of about one electron between adjacent atoms. Finally, the 3D maps for different properties reveal discernible property trends and enable material design.     

永磁同步电机矢量控制系统的研究

电机控制技术是实现高性能伺服驱动的核心,也是体现先进制造技术的标志技术之一。基于永磁同步电动机矢量控制理论,介绍了永磁同步电动机的数学模型和基于=0的矢量控制方法,建立了基于空间矢量的永磁同步电动机矢量控制系统Matlab仿真模型,并给出了仿真结果和系统软、硬件设计。硬件系统以TMS320F2812为核心,实现了电流、速度双闭环的矢量控制。仿真结果与理论分析一致,表明设计方案和控制策略的正确性。     

MIS系统中的预警机制

提出在ＭＩＳ系统中引入预警机制的新管理模式并给出了预警管理的实现方案。预警机制的应用,使管理信息系统显示出即时反应的活力,使管理更加智能化、规范化、制度化。实践结果表明,该文给出的解决方案是切实可行的,效果很好。     

熔融挤出接枝法制备HDPE／PA1010增容剂MPE

本文介绍用ＤＣＰＯ作引发剂，通过熔融挤出接枝法制备ＨＤＰＥ／ＰＡ１０１０共混体系增容剂ＭＰＥ的工艺研究。实验结果表明，通过熔融挤出法可将ＭＡＨ单体接枝于ＨＤＰＥ，接枝率和ＭＩ受挤出温度、螺杆转速、ＤＣＰＯ和ＭＡＨ用量的影响，其最佳工艺条件为：挤出温度范围１８０～２２０℃，螺杆转速２５ｒ／ｍｉｎ，ＤＣＰＯ和ＭＡＨ用量分别为０．３份和１．０～１．３份（树脂用量为１００份）。文中还对ＨＤＰＥ融熔挤出接枝     

基于均值查找的快速中值滤波算法

针对传统中值滤波算法时间复杂度高、运行速度慢,难以满足大型图像数据实时处理的问题,提出了一种快速中值滤波算法,将确定中值元素的过程由排序运算转换为基于均值对集合的二分查找,算法不依赖于滤波窗口的形状以及相邻窗口的相关信息,有效提高了中值滤波的执行效率,使传统中值滤波算法的时间复杂度由O(nln n)下降至O(n).实验中,该算法应用于大型图像序列的滤波处理,其运算速度提高到传统中值滤波算法的3倍以上,并且算法运行时间仅随滤波窗口大小线性增长,可以满足大尺度滤波窗口对大型图像数据实时处理的需求,具有显著的实际应用价值.     

Biocompatibility of FGL peptide self-assembly nanofibers with neural stem cells in vitro

In order to study the biocompatibility of self-assembled FGL peptide nanofibers scaffold with neural stem cells (NSCs), FGL pepitide-amphiphile (FGL-PA) was synthesized by solid-phase peptide synthesis technique. The diluted hydrochloric acid was added into FGL-PA solution to reduce the PH value and accordingly induce self-assembly. The morphological features of the assembled material were studied by transmission electron microscope. NSCs were cultured and added with self-assembled FGL-PA. CCK-8 kit was used to test its effect on the proliferation of NSCs. The differentiation of NSCs was also tested after FGL-PA assembled material added. The experimental results showed that FGL-PA could be self-assembled to form a hydrogel. TEM analysis showed the self-assembled hydrogel was nanofibers with diameter of 10–20 nm and length of hundreds nanometers. FGL-PA with concentrations of 50,100, or 200 mg/L could promote the proliferation of NSCs, and absorbance of them was increased (P<0.05). The rate of neurons differentiated from NSCs was improved greatly by FGL-PA assembled material compared with control (P<0.05). The findings suggested that FGL-PA could self-assemble to nanofiber hydrogel, which had good biocompatibility with NSCs.     

Metastable Ferroelectric Phase Induced by Electric Field in xPb(Zn1/3Nb2/3)O3–(1–x)Pb(Zr0.95Ti0.05)O3 Ceramics

A xPb(Zn_1/3Nb_2/3)O₃–(1–x)Pb(Zr_0.95Ti_0.05)O₃ (xPZN–(1–x) PZT) system close to antiferroelectric–ferroelectric (AFE–FE) morphotropic phase boundary has been prepared and investigated. The XRD results reveal PZN addition induces a phase transition from the orthorhombic (AFE) to rhombohedral (FE) phase through a phase coexistence region (AFE+FE). The polarization–electric field (P–E) measurements indicate that the AFE phase can be induced into a metastable FE (FE_m) phase. And the FE_m can recover to AFE around a critical temperature indicated by temperature‐dependent P–E loops. A composition‐temperature phase diagram was generalized within a certain range of PZN content in which an AFE–FE phase boundary connecting orthorhombic antiferroelectric to rhombohedral ferroelectric phase zones is formed near room temperature.     

纳米TiN粉分散工艺优化研究

运用超声分散技术研究了纳米 Ti N粉的分散性能 ,得到了优化的超声及分散工艺参数。实验结果表明 ,分散体系中表面活性剂的引入是必要的 ,表面活性剂的加入量要合适 ;非离子型表面活性剂的分散效果优于阴离子型表面活性剂 ;适当的超声时间及频率可以改善纳米 Ti N粉体系的分散状况。分散体系的 p H值对分散状况有一定的影响。     

磁控溅射制备纳米Ni-Ti薄膜工艺研究

为了得到高质量的纳米薄膜,对直流磁控溅射法制备Ni-Ti薄膜工艺进行了研究.采用单晶硅和玻璃两种基体材料,并在不同的基体温度、晶化温度、溅射功率等条件下制备薄膜.之后对薄膜进行了XRD,SEM分析.分析结果表明:薄膜成分、厚度、表面形貌、致密度与溅射功率、基体温度、晶化温度、基体材料密切相关.并根据实验结果给出优化的纳米Ni-Ti薄膜制备工艺.