烧结Nd-Fe-B磁体的角度差与取向度

用Helmholtz线圈测量了烧结Nd-Fe-B小立方磁体组合成大组件磁体的总磁矩,实验结果表明,高取向烧结Nd-Fe-B磁体的有效宏观磁矩符合矢量线性叠加原理。烧结Nd-Fe-B磁体的取向度越高磁矩角度差越小,但磁矩角度差小的磁体其取向度不一定高。同时利用有限元方法计算了Halbach阵列的磁力线分布。     

永磁铁氧体磁性能与料浆粒度关系的研究

注浆成型永磁铁氧体的磁性能与原始料浆颗粒的大小密切相关。通过工厂跟踪试验和实验室测试，深入分析了SrFe12O19。永磁铁氧体料浆颗粒大小对烧结后磁体的晶粒取向度、晶相结构和最终磁性能之间的关系。结果表明，料浆原始颗粒越小，则晶粒取向度越大，样品磁性能越好。     

Sr0.95Ca0.05Fe12O19六角铁氧体的微波特性

采用标准陶瓷工艺，并进行湿压磁场成型和氧气氛烧结，制备了目前尚未见报道的高取向度，低介电损耗的各向异性Sr0.95Ca0.05Fe12O19多晶六角铁氧体。研究了它们的比饱和磁化强度（δs)，磁晶各向异性场（H^A)同温度（T）的变化关系，并对其取向度进行了较深入的讨论。     

热等静压烧结Nd-Fe-B永磁体

热等静压烧结通常用来促进合金致密化和细化组织。本文尝试对Nd32．54Dy0．5Fe65．36Al0．6B1.0预烧结体分别进行热等静压烧结和常规烧结，旨在研究热等静压烧结能否促进Nd-Fe-B合金的致密化和晶粒细化。首次发现；高温热等静压烧结时，预烧结样品内的部分富Nd液相外流，在样品内形成空洞，被高压Ar气填充，造成样品不能收缩，磁体的密度比常规烧结磁体的低，力学性能明显恶化；且液相外流引起晶粒转动，导致取向度降低，最终磁体的剩磁和磁能积降低。     

X射线衍射法测定聚合物材料取向EI

介绍了用X射线衍射法测定结晶聚合物材料取向度定义,单轴和双轴取向及其计算方法。     

烧结条件对强磁场中成型氮化硅织构化的影响

采用凝胶注模成型方法在6T纵向强磁场中制备氮化硅陶瓷素坯,经磁场外无压烧结制备出a轴或b轴取向的织构化氮化硅陶瓷,研究了烧结温度和保温时间对氮化硅陶瓷织构化形成的影响规律。结果表明:在本文的烧结条件下α-Si3N4全部转变为β-Si3N4。烧结温度的提高促进了氮化硅陶瓷织构化的提高,从1700℃的0.40增加到1800℃的0.76。烧结温度为1750℃时,烧结时间的延长对织构度的发展几乎没有影响。     

烧结Nd—Fe—B取向度的研究

提出了一种用普通Ｘ射线衍射谱定量测量烧结Ｎｄ－Ｆｅ－Ｂ磁体取向度的简单易行的新方法,并与用１０－１２Ｔ强脉冲磁测量的Ｂｒ／Ｊｓ和（Ｂｒ∥－Ｂｒ）／Ｂｒ∥值进行了比较。为提高在金属模压工艺条件下的取向度,应加大取向外磁场或者采取减小磁粉与模具之间摩擦力的措施。     

永磁铁氧体磁性能与料浆粒度关系的研究

注浆成型永磁铁氧体的磁性能与原始料浆颗粒的大小密切相关.通过工厂跟踪试验和实验室测试,深入分析了SrFe12O19永磁铁氧体料浆颗粒大小对烧结后磁体的晶粒取向度、晶相结构和最终磁性能之间的关系.结果表明,料浆原始颗粒越小,则晶粒取向度越大,样品磁性能越好.     

烧结钕铁硼永磁体失重率测量不确定度评定

介绍了一种烧结钕铁硼永磁体失重率测量不确定度的评定方法,确定了测量方法和测量模型,分析了不确定度来源并计算了各项不确定度分量,最终给出了失重率测量不确定度的评定结果。     

陶瓷烧结过程孔隙演化的二维相场模拟

采用二维相场模型模拟陶瓷烧结过程中颗粒间孔隙的演化过程.选取四方堆积颗粒间气孔作为对象.通过连续的密度场和长程取向场（LRO）描述烧结体的微结构,密度场的演化由Cahn-Hillard（CH）方程控制,而颗粒的取向场演化由时间相关的Ginzburg-Laudau（TDGL）方程控制.上述非线性演化方程利用半隐傅立叶频域法求解.模拟结果反映了颗粒间接触,烧结颈生长和气孔球化的微观过程.量化计算烧结颈生长率以及在不同晶界和表面迁移率比值时的烧结率,较好地符合理论分析的趋势.     

Modification of the rotating jet method to generate highly aligned electrospun nanofibers

The rotating jet electrospinning method has been modified to increase the amount and the degree of alignment of electrospun nanofibers. For this purpose, the cylindrical collector of the rotating jet method (RJM) was replaced by two metallic concentric hollow cylinders. We called this improved technique; a modified rotating jet method (MRJM). The effectiveness of this method was evaluated with measuring the production rate and the degree of alignment of electrospun fibers and comparison of them with those obtained for the RJM. Our results disclosed that, the MRJM can improve the degree of alignment of electrospun fibers more than two times. Furthermore, when the voltage changed from 10 kV to 22 kV the average production rate of electrospun nanofibers was increased by 41% compared with the RJM.     

微细加工中的自动套准技术

对微细加工工艺中常用的三种套准方法做了详细的分析比较，并着重分析了最近发展起来的利用图像间的相关性实现套准的相关法，它能达到较高的套准精度，并具有一些独到的特点。     

Six-degrees-of-freedom alignment technique that provides diagnostic misalignment information

We introduce a new six-degrees-of-freedom alignment technique that enables the precise alignment of two optical device planes. The method combines linear diffraction gratings and cylindrical Fresnel lenses that allow the diagnosis of misalignment in each degree of freedom independently. The technique was used to align two 20 mm x 20 mm fused-silica substrates separated by 17 mm. The worst-case alignment precision was found to be better than +/- 5 microm laterally, +/- 20 microm longitudinally, +/- 0.036 degrees rotationally, and +/- 0.007degrees in tilt.     

On the effective electroelastic properties of microcracked generally anisotropic solids

In this study we first obtain the explicit expressions for the 15 effective reduced elastic compliances of an elastically anisotropic solid containing multiple microcracks with an arbitrary degree of alignment under two-dimensional deformations within the framework of the non-interaction approximation (NIA). Under special situations, our results can reduce to the classical ones derived by Bristow (J Appl Phys 11: 81–85, 1960), and Mauge and Kachanov (J Mech Phys Solids 42(4):561–584, 1994). Some interesting phenomena are also observed. For example, when the undamaged solid is orthotropic, the effective in-plane shear modulus is dependent on the degree of the crack alignment. The NIA method is then extended to obtain the effective electroelastic properties of an anisotropic piezoelectric solid containing two-dimensional insulat- ing, permeable or conducting microcracks with an arbitrary degree of alignment. We also derive a set of fifteen coupled nonlinear equations for the unknown effective reduced elastic compliances of a microcrac- ked, anisotropic, elastic solid by using the generalized self-consistent method (GSCM). The set of coupled nonlinear equations can be solved through iteration.     

Fabrication of Grain-oriented (Bi,Pb)_2Sr_2Ca_2Cu_3O_x Superconducting Tapes Using Magnetic Field and Vibration Technique

Highly textured (Bi,Pb)2Sr2Ca2Cu3Ox superconducting tapes have been fabricated by means of magnetic-field and vibration technique. This method is an effective way of improving the degree of grain alignment and density of oxide core in tapes after heat treatment and pressing cycles.Jc of above 20% was increased than that without treatment.     

船舶推进装置气囊隔振系统对中可控性问题研究

本文对船舶推进装置气囊隔振系统对中可控性问题进行了系统研究。通过建立控制响应计算模型、多目标对中控制模型,提出了对中可控性分析方法,使得控制系统能够根据不同工作情况自主调整控制系统工作参数,以保持良好的对中控制收敛性能,并通过实验验证了该方法的可行性。该方法已应用于某型船舶推进装置气囊隔振系统,成功实现了气囊柔性支撑状态下的推进装置高效隔振。     

Statistical analysis of the zero-phase method for aligning noisy high-resolution radar signals

Automatic target recognition using high-range resolution radars is a difficult task. Variations in the distance to the target cause circular shifts of the received signal, and most of the classification algorithms are very sensitive to shifts over the input signal. This fact makes the alignment of each signal prior to any classification stage very important. Here the alignment of noisy signals using the zero phase method is studied. In order to evaluate the performance of the alignment method, a theoretical analysis of the sensitivity to noise of this alignment method is carried out. As a result, an analytical expression that predicts the error of the alignment method is obtained. The validity of this expression is also confirmed by experimental results. A database of high-range resolution radar profiles containing patterns belonging to six different targets has been used, and a comparative study of the sensitivity to noise estimated using the profiles of the database and predicted by the analytical expression is carried out. The results demonstrate that the proposed analytical expression is useful to analyse the sensitivity to noise of the zero-phase alignment method for medium and high signal-to-noise ratio values.     

电场诱导碳纳米管在聚合物中定向有序排列的研究进展

碳纳米管特殊的结构和优异的性能使之成为复合材料增强的首选填料,综述了电场条件下碳纳米管在聚合物中有序排列的研究进展。分析了电场类型、碳纳米管表面官能化、加电时间、碳纳米管尺寸和含量等因素对电场诱导碳纳米管有序排列的影响,讨论了定向有序排列的碳纳米管对复合材料的力学、电学和热学等性能的影响,分析了碳纳米管定向排列机理以及碳纳米管定向程度的表征方法。     

Modeling electrical conductivities of nanocomposites with aligned carbon nanotubes

We have developed an improved three-dimensional (3D) percolation model to investigate the effect of the alignment of carbon nanotubes (CNTs) on the electrical conductivity of nanocomposites. In this model, both intrinsic and contact resistances are considered, and a new method of resistor network recognition that employs periodically connective paths is developed. This method leads to a reduction in the size effect of the representative cuboid in our Monte Carlo simulations. With this new technique, we were able to effectively analyze the effects of the CNT alignment upon the electrical conductivity of nanocomposites. Our model predicted that the peak value of the conductivity occurs for partially aligned rather than perfectly aligned CNTs. It has also identified the value of the peak and the corresponding alignment for different volume fractions of CNTs. Our model works well for both multi-wall CNTs (MWCNTs) and single-wall CNTs (SWCNTs), and the numerical results show a quantitative agreement with existing experimental observations.