CONSTRUCTING AND ANALYZING A CLASS OF CONTROLLABLE SEQUENCES

By using m-sequence over the finite field GF(2m) of degree L to control m-sequence over GF(2m) of degree L, a class of periodic sequences with large linear complexity is constructed. The lower bounds of the linear complexity of these sequences are L((L +1)m-Lm).     

控制能量受限下离散线性系统能控域结构*

本文讨论控制器能量受限时,线性系统的能控域结构,并给出解析表达式。     

Exploring regression structure with graphics

Summary We investigate the extent to which it may be possible to carry out a regression analysis using graphics alone, an idea that we refer to asgraphical regression. The limitations of this idea are explored. It is shown that graphical regression is theoretically possible with essentially no constraints on the conditional distribution of the response given the predictors, but with some conditions on marginal distribution of the predictors. Dimension reduction subspaces and added variable plots play a central role in the development. The possibility of useful methodology is explored through two examples. Read before the Spanish Statistical Society at a meeting organized by the Carlos III University of Madrid on Wednesday, April 21, 1993     

Facile fabrication of hollow mesoporous bioactive glass spheres: From structural behaviour to in vitro biology evaluation

Bone defects accompanied by infection or inflammation can significantly delay the healing process. To simultaneously achieve controlled release of local antibiotics for infection control and bone healing, bone-implantable delivery systems have been considered as a promising strategy. This study aims to improve drug loading capacity of bone-implantable delivery systems by introducing hollow structure mesoporous bioactive glass nanospheres (HMBGs) through a sol–gel process. Particularly, such core–shell bimodal-porous structured nanoparticles were prepared through a sacrificing template using cetyltrimethylammonium bromide (CTAB) as surfactant. It was found that varying the amount of CTAB during the synthesis process is a simple and effective approach for tuning the particle size, morphology, and structure of HMBGs. For in vitro drug release, HMBGs could sustain storage and release of vancomycin hydrochloride (VAN) via diffusion-controlled mechanism, thereby inhibiting the bacteria growth in the subsequent bacterial study. Moreover, HMBGs incorporated with VAN provided a biomimetic microenvironment favored by cell adhesion and proliferation. These findings support the compatibility of HMBG nanoparticles with antibiotics and their potential application in the treatment of infectious bone defects.     

用可控偏心器控制井眼轨迹的方法研究

井控轨迹自动控制技术是钻井行业急待解决的最前沿课题,用可控偏心器可以实现井眼轨迹自动控制,提高井眼轨迹控制精度,降低钻井成本。可控偏心器是一种井下可调的、可采用转盘钻进方式的井下寻向工具,它由翼片体转轴、翼片体、翼片和测控总成组成,在钻井过程中,通过随时调节可控偏心器翼片对井壁的作用力或伸缩来实现对井眼轨迹的控制。在使用可控偏心器进行钻井作业时,不需要频繁起下钻就可以在井下实现对井眼轨迹的控制,这对高难度密集丛式井、各种曲率斜井、水平井、加密井和抢险井等在完成各自的钻井目的方面有重大意义和极其宽广的应用前景。     

Controllable hydrothermal synthesis and morphology evolution of Zn4B6O13:Tb/Eu phosphors with tunable luminescent properties

A series of Tb, Eu single or co-doped Zn₄B₆O₁₃ phosphors with tetrahedral morphology were synthesized by facile hydrothermal method. The influences of reaction temperature and the pH value of the reaction system on the structures and compositions of product were also investigated, in which four kinds of zinc borates with different structures and compositions (Zn₄B₂O₇·H₂O, Zn₄B₆O₁₃, Zn(H₂O)B₂O₄·0.12H₂O, and H(Zn₆O₂(BO₃)₃)) were obtained. A possible growth mechanism of tetrahedral morphology of Zn₄B₆O₁₃ has been proposed according to reaction time. The obtained samples were characterized by XRD, EDS, SEM, TEM, XPS, BET, DR, PL and QY. XPS results indicate that Eu²⁺ and Tb⁴⁺ are present in Tb/Eu co-doped Zn₄B₆O₁₃, which might be generated from charge transfer between Tb³⁺ and Eu³⁺. The PL results shows that Eu³⁺, Tb³⁺ ion single-doped Zn₄B₆O₁₃ microstructure exhibit orange and green emission under ultraviolet excitation, respectively. Compared to Eu³⁺ and Tb³⁺ single doped Zn₄B₆O₁₃ phosphors, the Eu/Tb co-doped Zn₄B₆O₁₃ phosphors showed stronger blue emission of Eu²⁺. These results imply that the tetrahedral morphology of Eu³⁺, Tb³⁺ ion single-doped and Eu^2+/3+/Tb^3+/4+ co-doped Zn₄B₆O₁₃ phosphors have the promise application for nano/micro-optical functional devices.     

Controllable crystal growth of Mg(OH)2 hexagonal flakes and their surface modification using graft polymerization

Mg(OH)₂ crystals with excellent flame retardance in the application of polymer materials are always in demand. Herein, regular and well-dispersed Mg(OH)₂ hexagonal flakes were hydrothermally prepared with the existence of polyethylene glycol (PEG) and then modified by surface grafting-polymerization of methyl methacrylate (MMA) monomers. The results showed that the morphology and dispersity of Mg(OH)₂ relied on the precise control of the reaction parameters including hydrothermal conditions, the molecular weight and additive amount of PEG. PEG with a molecular weight of 8000 exhibited an enhanced directing role due to its more appropriate length of molecular chains and intensive interaction with the formed Mg(OH)₂ crystallites. The molecular chains of PEG-8000 can be preferentially adsorbed onto the (0 0 1) and (1 0 1) planes of Mg(OH)₂ crystallites and sub-micro hexagonal flakes with low-polarity were consequently assembled. The optimal conditions for preparing Mg(OH)₂ hexagonal flakes with higher crystallinity and more regular morphology were determined to be hydrothermal treatment at 120 °C for 12 h with 3 wt% PEG-8000. The dimension and decomposition temperature of the end products were 400 ~ 500 nm and 388 °C, respectively. The surface graft-modified Mg(OH)₂ hexagonal flakes exhibited high hydrophobicity with a water contact angle of 148°, indicating an excellent compatibility with polymers.     

电弧喷涂Al-Cu伪合金涂层的制备和性能研究

本文利用电弧喷涂技术在纯氩气气氛中成功制备出铝铜伪合金涂层.分析铝铜伪合金涂层的SEM照片,并测量其显微硬度和抗拉结合强度.结果表明:在纯氩气气氛电弧喷涂的涂层结合致密,缺陷很少.经过热处理后,铝铜形成了很好的结合,但部分铝被氧化,并形成了一些孔隙.随着热处理的温度升高,涂层的显微硬度先升高后降低,当温度在500℃时,...     

复内积空间上的一个等式

讨论了复内积空间上某向量与另一(两)个向量所张成的线性子空间的距离间的关系,得到了复内积空间上有关这些距离的一个等式.利用这一重要等式,首先证明了复内积空间上有关三个向量夹角余弦的一个不等式;其次,将G.Güss不等式在复内积空间下做了进一步的推广;最后利用这一等式对Ostrowski不等式做了推广.