基于并联集成光纤布拉格光栅的温度不敏感矢量弯曲传感器

本文提出一种利用飞秒激光逐线法制备并联集成光纤光栅阵列的技术,该光纤光栅阵列中的每个光纤光栅被制备在多模光纤纤芯轴向的相同位置但是径向的不同方位.利用该光纤光栅阵列实现了温度不敏感的矢量弯曲传感器,该传感器不仅可以实现弯曲曲率的测量,而且可以实现任意弯曲方向的判定.通过引入等效光纤光栅的解调方法,即对光纤光栅的反射波长...     

基于石墨烯/PEDOT:PSS复合材料制备的可穿戴柔性传感器

随着智能设备的普及,可穿戴电子设备呈现出巨大的市场前景.电阻式柔性应变传感器因具备较高的灵敏度与良好的生物兼容性等优点使其成为受关注的电学传感器.本文基于溶液共混法,制备一种新型的石墨烯(GR)/PEDOT:PSS多组分混合墨水材料,用直写喷墨打印技术制备了"电阻式"柔性应变传感器.该传感器以聚酰亚胺(PI)柔性薄膜为基底材料,以GR/PEDOT:PSS多组分混合墨水为导电材料,通过直写喷墨打印技术在柔性基底上打印导电图形.实验利用SEM、电学测试平台等表征手段分析了不同的GR掺加量对复合墨水材料性能与打印工艺的影响.实验结果表明:采用乙醇超声分散的GR材料可有效分布在PEDOT:PSS中,进而改善其在导电聚合物中的分散性;提高打印速率可明显降低线宽;随着GR掺加量的增大,柔性传感器阻值逐渐降低,器件的灵敏度下降;由此推断出相对疏松、分散性较好的墨水材料更有利于灵敏度的提高;提高柔性传感器的深宽比,可显著提高传感器的灵敏度.当弯折角度为80°时,电阻变化率(R/R0)最高为3.414,有望应用于柔性可穿戴设备新兴领域.     

新型可测量大变形的弯曲型光纤光栅裂缝传感器

光纤光栅传感技术以其自身的优势,在结构裂缝监测等工作中得到了广泛的应用,然而由于其自身很容易折断的特点,其测量的范围较小.在前人研究成果的基础上,设计了一种简易弯曲型光纤光栅裂缝传感装置,并通过实验对此传感装置的性能进行了验证.实验结果表明,本裂缝传感装置切实可行,可明显提高普通光栅光纤传感器的测量范围,而且具体良好的重复使用能力,以应对实际工程中裂缝开展情况的不确定性.     

闭环式逐点比较法联动控制的研究

利用垂直运动平台和旋转运动平台联动形成相对螺旋运动得到被测螺纹的包络轮廓面,是基于数字化包络轮廓面的螺纹综合参数测量法的重要测量环节之一。为满足螺纹综合测量机联动控制需要,提出一种基于光栅反馈的闭环式逐点比较联动控制方法。为保证控制系统的实时性,设计了基于硬件查询RAM速度表的速度和加速度驱动模式。通过改进开环式逐点比较法的偏差函数,将光栅反馈引入到其中,结合硬件查询RAM速度表的速度和加速度驱动模式形成了闭环式逐点比较法。理论分析表明,该控制方法联动轴向位置精度可达到0.1μm,具有控制平稳、超调量小等优点。仿真实验结果表明,该联动控制方法能够及时修正联动失调,实现高精度联动。     

一种新型瞬态量热计的研制

薄膜电阻温度计和同轴热电偶是两种常用的瞬态热流传感器,前者灵敏度高,但不适用于气流冲刷严重的场合;后者耐冲刷,但灵敏度较低,且响应特性易受结点细微结构的影响,只适用于高热流环境测量.基于量热计原理,本文提出了一种兼具两者优点的新型瞬态热流传感器.该传感器以金刚石片作为量热片,利用溅射其背面的铂膜电阻测出温度变化,而后由量热计原理得出表面热流.传感器的设计和优化借助了理论分析和数值计算,并讨论了可能引起测量误差的因素及解决方法.激波风洞试验结果表明:新型瞬态量热计灵敏度高耐冲刷,测量结果准确可靠,具有发展潜力.     

利用啁啾和波长同时可调谐的光纤光栅进行单模光纤色散补偿实验

提出一种利用悬臂梁同时调节光纤光栅中心波长和线性啁啾的新方法 .采用这一方法 ,对 1 0cm长的均匀光纤光栅实现了中心波长和啁啾的同时线性调谐 ,并将其应用于 1 9ps脉冲宽度、1 33km单模光纤的色散补偿实验中 ,取得了良好的补偿效果     

利用啁啾和波长同时可调谐的光纤光栅进行单模光纤？…

提出一种利用悬臂梁同时调节光纤光栅中心波长和线性啁啾的新方法。采用这一方法,对１０ｃｍ长的均匀光纤光栅实现了中心波长和啁啾的同时线性调谐,并将其应用于１９ｐｓ脉冲宽度、１３３ｋｍ单模光纤的色散补偿实验中,取得了良好的补偿效果。     

用弱相干白光双干涉系统测量光纤的蠕变

通过实验的方法研究了用于光纤传感器的光纤的蠕变特性. 设计了一个弱相干的白光干涉测量系统, 用该系统测量了光纤在静力拉伸和交变拉伸载荷作用下的蠕变. 研究结果表明, 对采用聚酯涂敷的光纤, 在静载和动载荷的作用下, 开始时均具有较大的蠕变, 但是随着静载作用时间的推移或交变载荷的循环次数的增加, 蠕变将停止. 为了保证压力光纤传感器中光纤的预应力, 建议光纤在装入传感装置以前预先加载一段时间或进行一定次数的拉-松循环加载消除光纤工作时可能产生的蠕变.     

PID神经网络控制在全自动多叶光栅中的应用

为满足全自动多叶光栅在Sliding工作模式下对光栅叶片的控制,要求具有很快的加速度和良好的动态性能以及很高的位置控制精度,提出了一种适用于该模式下的速度—位置双闭环电机控制模型,采用了神经网络与数字PID相融合的控制算法,并对该控制模型进行了仿真验证。实验表明:采用PID神经网络的速度—位置双闭控制具有很高的控制精度和良好的动态性能,能有效满足全自动多叶光栅Sliding工作模式的控制要求。     

石墨烯气凝胶全柔性触觉传感器的设计、组装及性能

针对柔性触觉传感器存在的设计难度大、抗干扰性差、不易封装以及线路布置困难等问题,基于Storakers材料模型的应变能密度函数发展了一种基于石墨烯气凝胶(graphene aerogel, GA)的具有“气泡膜”结构的全柔性触觉传感器的设计方法.通过模拟分析发现,相对于“三明治”结构,“气泡膜”结构的GA柔性触觉传感器具有更好的抗干扰性.在此基础上,设计并组装了“气泡膜”结构的GA全柔性触觉传感器,通过实验证实该GA全柔性触觉传感器具有优异的传感特性、力学特性和抗干扰特性.同时,设计开发了压阻式传感阵列的信号采集系统,并成功实现了其对力的大小、物体位置和形状等信息的实时采集和传感监测.     

路基上双块式无碴轨道道床板疲劳特性影响因素分析

以路基上双块式无碴轨道为研究对象,建立钢筋与混凝土纵向相互作用力学模型、双块式无碴轨道三维有限元静力学模型、列车-双块式无碴轨道垂向耦合动力学模型.根据轴向温度荷载、混凝土收缩荷载、温度梯度荷载及列车荷载作用下道床板混凝土及钢筋应力时程曲线,运用雨流计数法,得到耦合荷载作用下的应力谱.利用Miner线性疲劳累积损伤准则...     

Action de la pepsine sur un flagelle du type «9+1»

Summary Enzymatic extraction with pepsin was carried out on ultrathin sections of the 9 + 1 flagella ofDugesia tigrina, using the method ofMonneron andBernhard. The 9 peripheral fibrils and the axial zone of its unique central cylinder become altered within 40 min exposure; following 1 h of incubation these same elements are badly damaged, whereas the cortical sheath and associated radial spokes remain fairly well preserved inside the flagellar membrane. Control sections do not show any sensible alteration. The protein nature of peripheral doublets and axial element of the central cylinder seems therefore indicated; the cortical sheath and the spokes have a very similar, if not identical nature, though their chemical constitution still remains to be investigated.     

Highly homologous HERC proteins localize to endosomes and exhibit specific interactions with hPLIC and Nm23B

Small HERC proteins are defined by the presence of one RCC1-like domain and a HECT domain. Having evolved out of one common ancestor, the four members of the family exhibit a high degree of homology in genomic organization and amino acid sequence, thus it seems possible that they might accomplish similar functions. Here we show that small HERC proteins interact with each other and localize to the same cellular structures, which we identify as late endosomes and lysosomes. We demonstrate interaction of HERC3 with the ubiquitin-like proteins hPLIC-1 and hPLIC-2 and we establish interaction of HERC5 with the metastasis suppressor Nm23B. While hPLIC proteins are not ubiquitinated by HERC3, HERC5 plays an important role in ubiquitination of Nm23B. In summary, although small HERC proteins are highly homologous showing the same subcellular distribution, they undergo different molecular interactions.     

Functional similarities in the mechanical design of the aorta in lower vertebrates and mammals

The mechanical properties of the aorta from the toad Bufo marinus, the lizard Gekko gecko and the garter snake Thamnophis radix were compared to those of the rat, by inflation of vessel segments in vitro. The arteries of the lower vertebrates, like those of mammals, were compliant, highly resilient, and non-linearly elastic. The elastic modulus of the artery wall was similar in the lower vertebrates and mammals, at their respective mean physiological pressures. We conclude that the aorta in each of these animals is suitably designed to function effectively as an elastic pulse smoothing component in the circulation; differences in the pressure wave transmission characteristics of lower vertebrates and mammals do not result from dissimilarities in arterial elastic properties, but from substantial differences in heart rate of these two groups.     

Cilia in stellate neurons of the rat cerebellum

Summary Cilia in stellate neurons of the normal rat cerebellum are described. 8 cilia were observed in a total of 60 cells studied. An 8+1 pattern was found throughout their length. Furthermore, no arms, spokes or other accessory structures necessary for ciliary motion were seen. These findings make it possible to suggest that these cilia are probably without function and are related to the epithelial origin of these cells.This work was granted by INIC: Centro de Morfologia Experimental (MbP₁).Acknowledgments. The authors thank M.A. Rodrigues, M. M. Pacheco, M. C.Pinho and L. B. Nunes for technical assistance.     

The Young's moduli prediction of random distributed short-fiber-reinforced polypropylene foams using finite element method

The elastic moduli of short-fiber-reinforced foams depend critically on the fiber content and fiber length,as well as on the fiber orientation distribution.Based on periodic tetrakaidecahedrons,the finite element models with short-fiber reinforcement were proposed in this paper to examine the effects of the fiber content and fiber length on Young's modulus. The fiber length distribution and fiber orientation distribution were also considered.The proposed models featured in a three-dimensional diorama with r...     

坚硬顶板深孔爆破卸压技术及其模拟优化

工作面回采过高冲击危险区时,采用深孔爆破技术,提前释放坚硬顸板内储存的弹性能,可以降低冲击危险,能有效地避免冲击地压灾害发生。以济三煤矿6303工作面实际地质情况为研究背景,从岩石爆破机理出发,计算出合理的钻孔间距;利用Ansys有限元非线性动力学软件,对不同爆破孔间距深孔预爆破方案和爆破效果进行爆破效果模拟,分析了爆破应力波传播规律和裂纹扩展情况,找出最优爆破参数。     

Zur Bestimmung der Elastizitätsgrenze von Bindegewebsstrukturen in vitro

Summary Biological connective tissues are not perfectly elastic. They contain viscous, friction, and elastic elements. Consequently, complex mechanical behaviour can be observed. It is not possible to determine an elastic limit, as in inorganic solids. There are difficulties in measuring a natural state which can serve as a reference for mechanical testing procedures. The method described generates a steady state in the test specimen and allows the determination of a relative elastic limit.     

Structural basis of bacterial defense against g-type lysozyme-based innate immunity

Gram-negative bacteria can produce specific proteinaceous inhibitors to defend themselves against the lytic action of host lysozymes. So far, four different lysozyme inhibitor families have been identified. Here, we report the crystal structure of the Escherichia coli periplasmic lysozyme inhibitor of g-type lysozyme (PliG-Ec) in complex with Atlantic salmon g-type lysozyme (SalG) at a resolution of 0.95 Å, which is exceptionally high for a complex of two proteins. The structure reveals for the first time the mechanism of g-type lysozyme inhibition by the PliG family. The latter contains two specific conserved regions that are essential for its inhibitory activity. The inhibitory complex formation is based on a double ‘key-lock’ mechanism. The first key-lock element is formed by the insertion of two conserved PliG regions into the active site of the lysozyme. The second element is defined by a distinct pocket of PliG accommodating a lysozyme loop. Computational analysis indicates that this pocket represents a suitable site for small molecule binding, which opens an avenue for the development of novel antibacterial agents that suppress the inhibitory activity of PliG.