Automatic scatter detection in fluorescence landscapes by means of spherical principal component analysis

In this paper, we introduce a new method, based on spherical principal component analysis (S‐PCA), for the identification of Rayleigh and Raman scatters in fluorescence excitation–emission data. These scatters should be found and eliminated as a prestep before fitting parallel factor analysis models to the data, in order to avoid model degeneracies. The work is inspired and based on a previous research, where scatter removal was automatic (based on a robust version of PCA called ROBPCA) and required no visual data inspection but appeared to be computationally intensive. To overcome this drawback, we implement the fast S‐PCA in the scatter identification routine. Moreover, an additional pattern interpolation step that complements the method, based on robust regression, will be applied. In this way, substantial time savings are gained, and the user's engagement is restricted to a minimum, which might be beneficial for certain applications. We conclude that the subsequent parallel factor analysis models fitted to excitation–emission data after scatter identification based on either ROBPCA or S‐PCA are comparable; however, the modified method based on S‐PCA clearly outperforms the original approach in relation to computational time. Copyright © 2013 John Wiley & Sons, Ltd.     

A model of the effects of authority on consensus formation in adaptive networks: Impact on network topology and robustness

Opinions of individuals in real social networks are arguably strongly influenced by external determinants, such as the opinions of those perceived to have the highest levels of authority. In order to model this, we have extended an existing model of consensus formation in an adaptive network by the introduction of a parameter representing each agent’s level of ‘authority’, based on their opinion relative to the overall opinion distribution. We found that introducing this model, along with a randomly varying opinion convergence factor, significantly impacts the final state of converged opinions and the number of interactions required to reach that state. We also determined the relationship between initial and final network topologies for this model, and whether the final topology is robust to node removals. Our results indicate firstly that the process of consensus formation with a model of authority consistently transforms the network from an arbitrary initial topology to one with distinct measurements in mean shortest path, clustering coefficient, and degree distribution. Secondly, we found that subsequent to the consensus formation process, the mean shortest path and clustering coefficient are less affected by both random and targeted node disconnection. Speculation on the relevance of these results to real world applications is provided.     

An image encryption scheme based on rotation matrix bit-level permutation and block diffusion

This paper proposes a novel image encryption scheme based on rotation matrix bit-level permutation and block diffusion. Firstly, divide plain image into non-overlapping 8 × 8 pixels blocks with a random matrix, then transform each block into an 8 × 8 × 8 three-dimensional (3-D) binary matrix, which has six directions just as a cube. Permutation is performed by multiplying the 3-D matrix by the rotation matrix that relies on plain image according to different direction. Secondly, use block diffusion to further change the statistical characteristics of the image after confusion. Experiment results and analysis show that the scheme can not only achieve a satisfactory security performance, but also have the suitability for a parallel mode and the robustness against noise in communication system.     

Robustness of F-tests in singular linear models

F-test is the most popular test in the general linear model. However, there is few discussions on the robustness of F-test under the singular linear model. In this paper, the necessary and sufficient conditions of robust F-test statistic are given under the general linear models or their partition models, which allows that the design matrix has deficient rank and the covariance matrix of error is a nonnegative definite matrix with parameters. The main results obtained in this paper include the existing findings of the general linear model under the definite covariance matrix. The usage of the theorems is illustrated by an example.     

改进的CATSMLP预警藻类污染

人工神经网络由于其很多的特点与优势现已被广泛关注和运用.但是人工神经网络也存在学习过程易陷入局部极小、易出现震荡和网络存在冗余连接或节点等缺陷.针对这些不足,一种新的级联M LP神经网络CATSM LP比ATSM LP有更好的鲁棒性和高度的解释性,并且是一个万能逼近器.采用粒子群优化算法对其进行优化使其鲁棒性增强,具有更快速的收敛能力和更好的寻优能力,从而能更有效的建模.藻类的生长是湖泊等水体污染程度的一个直接表现形式.在某些情况下,甚至精密仪器都不能测出某些藻类污染物,因此需要好的方法越来越受到专家学者们的重视.将其用于藻类污染预警,仿真试验表明其用于环境污染防治有很好的效果,值得推广应用.     

High-fidelity resonant tunneling passage in three-waveguide system

An N-stage three-waveguide system is proposed to improve the robustness and the fidelity of the resonant tunneling passage.The analytic solutions to the tunneling dynamics at the output are derived.When the number of subsystems increases,tunneling efficiency approaches to 100%in a large range and resonant tunneling is robust against variations in the phase mismatch and peak tunneling rate.     

Short transient signals, a challenge for inductively coupled plasma mass spectrometry, a review

The ability to acquire and handle short transient signals is key in order to open new applications for inductively coupled plasma mass spectrometry (ICP-MS), for example, in life sciences. Technological and methodological achievements are reviewed to show challenges and capabilities of short transients in ICP-MS technology or hyphenated techniques. The dynamic processes in the plasma need to be controlled or observed to assure quality of quantitative results. Most precise instrumentation is to date multiple collector sector field MS but drifting isotope ratios are observed in transient signals using these instruments, thus limiting precision of such measurements and leaving unknowns in quantitative results. TOFMS in principle provides fast simultaneous multi-element detection, scanning instruments like quadrupole MS or scanning sector field MS are fundamentally restricted. However, new commercial ICP-MS instruments can be expected in the near future, making short transients more and more attractive to shorten acquisition times and to increase signal to noise ratio of element analyses.     

Guaranteed stability margins and singular value properties of the discrete-time linear quadratic optimal regulator

Useful singular value properties for the state feedback discretelinear quadratic (LQ) optimal regulator are established. Inparticular, new lower bounds for the minimum singular valueof the regulator's return difference matrix are suggested. Onthe basis of these bounds, new guaranteed stability marginsfor such a type of LQ regulator are established. These marginsare more relaxed than the guaranteed stability margins proposedin the literature. Furthermore, our investigation provides guaranteedstability margins in cases where known techniques fail. Moreover,it is verified that, in contrast to what happens in the continuous-timecase, the singular values of the closed-loop transfer functionof the discrete LQ regulator can be, in general, greater thanthe singular values of the open-loop transfer function. Moreover,in the case of the output-weighted cost function, the singularvalues of the closed-loop transfer function of the discreteLQ regulator can be, in general, greater than the output-weightingparameter. In this respect, new results relating the singularvalues of the closed-loop and the open-loop transfer functionsof the discrete LQ regulator, are also established.     

Optimum Radius of Robust Stability for Schur Polynomials

The paper investigates the problem of the robust stability of Schur polynomials. Recently, a new approach based on the Rouche theorem of classical complex analysis has been adopted for the solution of this problem. In this paper, an improvement of the previous solution is presented. This is the optimum solution of the robust stability problem for Schur polynomials, which is obtained by solving a minimization problem and is better than other methods in robust stability literature. Three numerical examples are given to illustrate the proposed method.     

On the robustness of the BPX-preconditioner with respect to jumps in the coefficients

We determine the worst case behavior of the standard BPX-preconditioner for elliptic problems with arbitrary coefficient jumps along the boundaries of the coarsest partition. The counterexamples are also useful for other problems.