复杂度为n+2的序列(英文)

本文研究了复杂度为n+2的序列.利用代换的理论以及词上组合的方法,刻画了这类序列,揭示了它们与Sturmian序列的密切联系.     

约束下线性混合模型参数估计的渐近解及其收敛性

在线性不等式约束下讨论了具有相同参数的两个线性混合模型的参数估计问题,给出了一种迭代算法,得到了这类模型中参数的最小二乘估计序列及其渐近解.在此基础上,利用多元多项式方程组解的个数定理和不动点定理,证明了此估计序列是依概率1收敛的.     

Dielectric-breakdown-like forming process in the unipolar resistance switching of Ta2O5−x thin films

We report unipolar resistance switching (URS) in Ta₂O_5−x thin films. The current increased suddenly when we applied voltages up to 5-7 V to the pristine state of Pt/Ta₂O_5−x/Pt, Ni/Ta₂O_5−x/Pt, and Ti/Ta₂O_5−x/Pt cells. Just after this forming process, we observed a repetitive URS occurring independently of the electrodes. We found that the required voltages for the forming process did not depend on the top electrode type, but on the film thickness. These results suggest that the forming process is driven by a dielectric-breakdown-like phenomenon, and that URS occurs due to the formation and rupture of conducting channels inside the Ta₂O_5−x thin film.     

Role of anisotropy on the domain wall properties of ferromagnetic nanotubes

In this paper we investigate the role of magneto-crystalline anisotropy on the domain wall (DW) properties of tubular magnetic nanostructures. Based on a theoretical model and micromagnetic simulations, we show that either cubic or uniaxial magneto-crystalline anisotropies have some influence on the domain wall properties (wall size, propagation velocity and energy barrier) and then on the overall magnetization reversal mechanism. Besides the characterization of the transverse and vortex domain wall sizes for different anisotropies, we predict an anisotropy dependent transition between the occurrence of transverse and vortex domain walls in tubular nanowires. We also discuss the dynamics of the vortex DW propagation gradually increasing the uniaxial anisotropy constant and we found that the average velocity is considerably reduced. Our results show that different anisotropies can be considered in real samples in order to manipulate the domain wall behavior and the magnetization reversal process.     

Investment in electricity networks with transmission switching

We consider the application of Dantzig-Wolfe decomposition to stochastic integer programming problems arising in the capacity planning of electricity transmission networks that have some switchable transmission elements. The decomposition enables a column-generation algorithm to be applied, which allows the solution of large problem instances. The methodology is illustrated by its application to a problem of determining the optimal investment in switching equipment and transmission capacity for an existing network. Computational tests on IEEE test networks with 73 nodes and 118 nodes confirm the efficiency of the approach.     

合数模上的伪随机二进制数列

设m为"RSA"类型的模,即m为两个大小差不多的素数的乘积:m=pqp,q为素数,p相似文献   

Detection of DNA Hybridization via Fluorescence Intensity Variations of ZnSe-DNA Quantum Dot Biosensors

ZnSe quantum dots (QDs) that were capped with 11-mercaptoundecanoic acid (MUA) and conjugated to amino-modified ssDNA molecules exhibited variations in fluorescence emission intensity upon hybridization with complementary ssDNA in solution, a phenomenon that can be exploited for rapid detection of free ssDNA sequences. Conjugation of MUA-capped ZnSe QDs to amino-modified ssDNA molecules resulted in increased fluorescence emission intensity and stability at room temperature. Increasing the length of the ssDNA, that was conjugated to the QDs, resulted in increased fluorescence emission intensity up to a length of about 50 nucleotide bases, beyond which the peak emission intensity reached a plateau. Hybridization of QD-ssDNA conjugates with complementary ssDNA, either in free form or bound to QDs from the same population, resulted in additional fluorescence emission intensity amplification. A small red shift was observed when three-dimensional QD-dsDNA-QD structures were formed. The QD-ssDNA sensors with single ssDNA molecule per QD were developed and used for rapid quantitative detection of fully or partially complementary free ssDNA sequences in aqueous solution. Partial hybridization of the QD-ssDNA sensors with short ssDNA targets resulted in smaller QD emission intensity amplification, when compared to full hybridization. A QD-ssDNA sensor containing a sequence corresponding to the hemoglobin beta gene was used to detect and discriminate between free ssDNA targets consisting of a complementary ssDNA sequence and targets containing a single-base mutation that can cause sickle-cell anemia. Such QD-based biosensors can form the basis for rapid separation-free assays that can be used to detect target biomolecules in solution.     

Theoretical investigation on redox-switchable second-order nonlinear optical responses of push-pull Cp*CoEt2C2B4H3-expanded (metallo)porphyrins

The second-order nonlinear optical (NLO) properties of the Cp*Co(C(2)H(5))(2)C(2)B(4)H(3)-expanded (metallo)porphyrins (Cp* = C(5)Me(5)) have been investigated by using ab inito RHF and density functional theory (DFT) methods. The investigation shows that the compound with expand porphyrin possesses remarkable large molecular hyperpolarizability β(tot) value, ~414.1 × 10(-30) esu (at LC-ωPBE level), and might be an excellent second-order NLO material. From the character of charge transfer (CT) transition, it indicates that the -Cp*Co(C(2)H(5))(2)C(2)B(4)H(3) acts as an electron donor in this kind of systems. As a result of the redox behavior on expanded (metallo)porphyrin, the redox switching character of the NLO responses for the systems 2a-4a has also been studied. The results show that the β(tot) values of reduced forms are larger than that of neutral ones. Furthermore, the time-dependent DFT calculation illustrates that reduced forms have a significant difference on the CT patterns versus neutral ones. The present investigation provides insight into the comparison with DFT results on estimating first hyperpolarizability and the NLO properties of the series of push-pull compounds.