Structure, properties, and thermal stability of nanocrystallite Fe-Ti-N soft magnetic films

We deposited Fe-Ti-N magnetic films with a high sputtering power of 7 W/cm/sup 2/. When the composition of the films was in the range of Fe-Ti(3.9 at.%)-N(8.8 at.%) to Fe-Ti(3.3 at.%)-N(13.5 at.%), the films were composed of /spl alpha/' and Ti/sub 2/N precipitates. With the addition of nitrogen, 4/spl pi/M/sub s/ became higher than that of pure iron, reaching a maximum of 23.8 kG. At the same time, H/sub c/ was reduced to a minimum of 1.12 Oe. The best films can meet the needs of the recording head in dual-element giant magnetoresistive/inductive heads, yielding high storage density (10 Gb/in/sup 2/). The incorporation of N in /spl alpha/-Fe brought about the /spl alpha/' phase with its higher saturation magnetization. Ti additions inhibited the equilibrium decomposition /spl alpha/'/spl rarr//spl alpha/+/spl gamma/'. Because H/sub C//sup D//spl prop/D/sup 6/, where D is average grain diameter, grain size control is very important. The nitrogen induces severe distortion of the /spl alpha/' lattice, which can cause the grains to break into pieces and reduce the grain size. High sputtering power also led to the formation of fine grains, with diameter in the order of 14 nm. Probably Ti/sub 2/N is preferentially precipitated on the grain boundary, pinning the grain boundary and stabilizing the grain size during high-temperature heat treatment. The temperature limit for stability of the structure and its associated low coercivity was not less than 520/spl deg/C.     

基于压电陶瓷动态信息的结构裂纹识别方法

利用压电陶瓷的动态特性和压电系统的动态信息,对铝梁的裂纹损伤进行了分析研究。随着梁裂纹尺寸的增加,压电陶瓷片的导钠幅值下降,且系统固有频率减小。利用导钠幅值的变化和系统的动态信息,可以对裂纹的位置和尺寸大小进行识别。实验证明该方法的有效性。     

Cover Picture: Arresting,Fixing, and Separating Dimers Composed of Uniform Silica Colloidal Spheres (Adv. Funct. Mater. 12/2006)

In colloidal suspensions of silica, particles undergo constant collisions. By controlling various parameters, the repulsive barrier can be reduced, thereby substantially increasing the number of collision‐induced dimerization events. Xia and co‐workers report on p. 1627 that the dimers could be arrested and then permanently fixed by introducing a small amount of fresh tetraethylorthosilicate into the colloidal suspension, with monodisperse dimer yields of up to 50 %. This yield could be increased to 80 % by centrifugation in a density gradient medium. When fresh tetraethylorthosilicate is introduced into a colloidal suspension of silica spheres, it hydrolyzes and condenses in situ to arrest and fix the dimers resulting from constant collisions between the spheres. By optimizing the experimental parameters (including the length of aging time) and the diameter of the silica spheres, as well as the concentrations of counterions, water, and ammonia, it is possible to routinely produce monodisperse dimers with a yield as high as 50 %. When combined with centrifugation using a density gradient medium, the yield of such dimers could be further increased to 80 %. It is believed that this method will provide a simple and versatile approach to the high‐volume production of dimers from spherical colloids composed of different materials. These dimers may find widespread use in a range of applications such as fabrication of photonic crystals and fundamental studies related to colloidal science.     

XMAC纵波时差高分辨率处理方法

在充分调研阵列声波测井分波提取方法的基础上，针对阿特拉斯公司的交叉多极子阵列声波测井（XMACⅡ）提供的单极波形信息，研究纵波时差提取及高分辨率处理方法。首先利用相关-互功谱法高精度地提取纵波时差，然后针对XMACⅡ仪器的接收阵列，研究组合子阵列的方法，形成共发射子阵列和共接收子阵列，最后利用子阵列对提取的纵波时差做高分辨率处理。处理现场实际测井资料，并将高分辨率处理成果与引进的eXpress软件处理成果、实测的国产高分辨率声波（纵波）测井曲线及岩心纵波时差对比分析，表明该方法提取的纵波时差曲线的纵向分辨率有很大提高，时差计算准确可靠，提取的单极纵波时差与国产高分辨率声波时差及岩心纵波时差的平均相对误差均小于7%。该方法具有较高的实用价值和广阔的应用前景。     

含硫化氢气井钻井过程中的腐蚀因素与防护研究

在含硫气井的钻井过程中对于HRC大于22的钻具钢材除了腐蚀疲劳之外，在pH值小于9的环境中会发生硫化物应力腐蚀破裂，这种破坏比腐蚀疲劳更突然、更快，使钻杆大量损坏。含硫气井在钻井过程中，由于湿硫化氢的出现，常常会出现油管、套管、钻井设备、钻井仪器以及对支持保护管柱的水泥环柱等腐蚀和损坏问题，为此，阐述了湿硫化氢的腐蚀特点、机理，归纳总结了影响腐蚀的因素，综述了如何在这些方面防止其腐蚀，使损失减小，为指导油管、套管防腐工程实践提供了依据。建议在钻井过程中采用碱性钻井液，其pH值可到9或更高(至pH值12)，以减缓或防止钻井过程中电化学从硫化物应力腐蚀破裂；含硫气井用的钻杆应该间歇使用。钻杆停用堆置时间可使其放氢，使钻杆恢复韧性，防止硫化物应力腐蚀断裂。     

外源乙烯对黄瓜幼苗根系生长及内源多胺含量的影响

精确控制营养液溶氧浓度和外源乙烯浓度,研究了黄瓜幼苗根系在低氧水培时的生长情况以及PAs含量的变化。结果表明,外源乙烯对根际低氧逆境下黄瓜幼苗根系的生长有抑制作用,虽然根径增粗,含水量增加,但根系的总根数、总表面积、总体积、干重和鲜重都有所减少,随着乙烯浓度的增加,抑制作用增强;外源乙烯对根际低氧逆境下黄瓜幼苗根系PAs含量有着明显的拮抗作用,外源乙烯使根际低氧逆境下黄瓜幼苗根系的伤害症状加重。     

向家坝水电站右岸隧道进出口边坡的处理研究

文章主要从实践方面介绍了向家坝水电站右岸地方还建公路北线段隧道洞口施工期边坡缺陷处理措施,并总结了几点经验,这对于以后公路隧道洞口的设计和施工,尤其是洞口边坡塌方的处理具有一定指导意义。     

浅谈如何有效学习计算机软件知识

计算机软件知识的学习并不是完全线性的，而是不断循环往复、迭代的过程。本对如何深入、广泛、有效地学习计算机软件知识做出了一些探讨。     

SCB火工品的研究与发展

文章评述了半导体桥火工品问世以来的研究成果与发展趋势。主要内容有半导体桥作用机理、半导体桥的结构与封装、半导体桥火工品的特点、半导体桥火工品的应用、半导体桥火工品的研究和发展趋势。     

Image registration by "Super-curves"

We solve the 2-D affine image registration problem by curve matching and alignment. Our approach starts with a super-curve, which is formed by superimposing two affine related curves in one coordinate system. We use B-spline fusion technique to find a single B-spline approximation of the super-curve and a registration between the two curves simultaneously. This approach achieves superior accuracy and efficiency in curve matching and alignment. We then address the occlusion problem by finding partial match between the curves segmented using inflections and cusps, which are affine invariant. The combination of edge detection and curve alignment lead to accurate image registration.