Representation of 3D Woven Structures by Parametric Method

A parametric method is developed to quantitatively represent the microstructure of 3D woven structures. Different binding patterns, such as angle interlock and orthogonal interlock with through-thickness or layer-to-layer bindings, are classified. A unit cell of 3D woven structure is defined with four constituent yarn systems represented by nine structural parameters. A mapping relationship between the 3D woven structure and corresponding representative parameters is thus established. The study indicates that four out of the nine parameters are necessary to represent a 3D woven structure with an angle interlock binding, and that five parameters are required to describe a 3D woven structure with an orthogonal interlock binding. Once the structural parameters are determined, the pattern of 3D woven structures can be unambiguously identified, and vice versa. In addition to the purpose of structure presentation, the method can be further used as a means for designing 3D woven structure to meet the performance requirements of 3D woven composites.     

现代放疗的体位固定技术与发展

在我国虽然放疗开展起步较晚,但发展很快.体位固定装置使用,使得放疗的重复性和稳定性得到了一个很大的提高.随着放疗技术的发展,放疗的体位固定装置也得到了不断的完善和改进.逐一介绍现代放疗中各部位的体位固定技术的操作程序及操作要点,以提高放射治疗的精度.     

论排球二传队员战术意识的培养

随着排球比赛竞争的日益激烈，排球比赛场上千变万化，作为排球的二传队员要具有娴熟的手上功夫、良好的身体素质、顽强的精神、较好的心理素质及优良的战术意识来捕捉瞬时的战机．其中战术意识的培养至关重要，本文对排球二传队员战术意识的培养进行了论述．     

A New Self-assembly Metal CMG Discriminator by Multi-exposure LiGA Like Process and Sacrificial Layer Process

The counter-meshing gears （CMG） discriminator is a mechanically coded lock, which is used to prevent the occurrence of High Consequence Events. This paper advanced a new kind of self-assembly metal CMG discriminator based on multi-exposure LiGA like process and sacrificial layer process. The new CMG discriminator has the following characters except low cost： 1） it has only discrimination teeth sections; 2） the thickness of each gear layer exceeds one hundred micrometers; 3） it is axially driven by a separate dectronic magnetic micromotor directly; 4） its CMG is made of metal and is batch fabricated in the assembled state; 5） it is prevented from rotating in the opposite direction by pawl/ratchet wheel mechanism; 6） it has simpler structure. This device has better strength and reliability in abnormal environment compared to the existing surface micro machining （SMM） discriminator.     

基于自适应提升小波变换多分辨率数据融合

建立了基于小波去噪的多分辨率多传感器数据融合模型 ,引入了提升法自适应离散小波变换 ,根据最小均方 (LMS)自适应法确定伯恩斯坦 (Bernstein)提升滤波器的权系数 ,使其匹配低分辨率传感器的数据序列 ,接着使其对高分辨率采样数据的小波分解的尺度系数进行数据更新 ,实现不同分辨率数据的融合。最后对不同分辨率三传感器测量系统进行了数值仿真。实验结果表明 ,该方法可以有效地实现多分辨率多传感器数据融合 ,而且消除了噪声干扰 ,提高了系统的测量精度。     

关于二值马氏链的一个强大数定律

引进了二值随机变量序列相对于二值马尔可夫链的随机比较系数的概念,利用这个概念给出了二值马尔可夫链的一个新的强大数定律.     

1, 3-dioxolane pretreatment to improve the interracial characteristics of a lithium anode

1,3-dioxolane （DOL） was originally used to pretreat a lithium metal electrode to improve its interracial characteristics. Electrochemical impedance spectra （EIS） measurements revealed that, after the DOL pretreatment, the lithium electrode had better interfacial stability during immersion in electrolyte and as repeated charge/discharge cycles. It was proved by SEM that the pretreated one has smoother morphology and less dendrite after repeated charge/discharge cycles. Consequentially, benefiting from the better interface characteristics of the lithium electrode.     

一种大功率连续波磁控管的高频电磁场与热应力场耦合分析

本文发展一种应用于大功率连续波磁控管腔体的高频电磁场-热应力场耦合分析方法。首先,采用等效电路理论与数值仿真方法研究一种大功率连续波磁控管谐振系统在无隔模带、单环隔模带和双环隔模带情形下的工作模式、谐振频率和品质因数的内在关系;其次,对扇形和扇槽形阳极叶片的温度分布进行理论推导。研究发现,隔模带能够提高谐振系统的模式分隔能力,但也会增大损耗、降低品质因数;再者,通过对比不同冷却条件下谐振系统的热应力、形变、温度和谐振频率,设计出满足30kW连续波输出磁控管散热的冷却水路和相匹配的冷却条件;最后,结合二者得到阳极叶片温度与π工作模式谐振频率间的对应关系并给出磁控管的热漂移曲线。     

Microwave-assisted sol-gel synthesis of hydroxyapatite nanoparticles

A rapid sol-gel method for preparing hydroxyapatite nanoparticles(nHAP) has been developed. Three different sets of experimental conditions, in terms of solvents(water and ethanol), synthesis temperatures(25, 40 and 60℃), and microwave irradiation(on and off) were explored. Crystal phase composition, functional groups and morphology of the products were characterized by thermogravimetric analysis(TGA), X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The solvent and temperature were optimized based on product properties. Most importantly, the microwave-assisted method(with little to no ageing necessary) was much faster than the conventional methods(with slow ageing processes needing from hours to days), while affording pure nHAP with virtually identical morphological and structural properties. This study represents a practical application of the powerful microwave technique in synthesis of nHAP, offering guidance on the selection of optimum experiment conditions.     

基于凸组合的移动平均线策略应用研究

鉴于随着市场有效性的增强,作为量化投资技术分析中重要指标之一的传统移动平均线策略逐渐失效。基于凸组合思路构建改进移动平均线策略,并给出了策略交易规则。对2005年10月17日-2017年12月31日的日收盘价数据进行不同日期参数的均线策略回测检验,结果表明：基于凸组合的移动平均线策略表现优于传统移动平均线策略,日期参数组合5~20的凸组合策略表现最好,基于凸组合的移动平均线策略具有较好的应用价值。