Modeling and analysis of energy distribution networks using switched differential systems

It is a pleasure to dedicate this contribution to Prof. Arjan van der Schaft on the occasion of his 60th birthday. We study the dynamics of energy distribution networks consisting of switching power converters and multiple (dis-)connectable modules. We use parsimonious models that deal effectively with the variant complexity of the network and the inherent switching phenomena induced by power converters. We also present the solution to instability problems caused by devices with negative impedance characteristics such as constant power loads. Elements of the behavioral system theory such as linear differential behaviors and quadratic differential forms are crucial in our analysis

Prediction of conformational B-cell epitopes from 3D structures by random forests with a distance-based feature

<p>Abstract</p> <p>Background</p> <p>Antigen-antibody interactions are key events in immune system, which provide important clues to the immune processes and responses. In Antigen-antibody interactions, the specific sites on the antigens that are directly bound by the B-cell produced antibodies are well known as B-cell epitopes. The identification of epitopes is a hot topic in bioinformatics because of their potential use in the epitope-based drug design. Although most B-cell epitopes are discontinuous (or conformational), insufficient effort has been put into the conformational epitope prediction, and the performance of existing methods is far from satisfaction.</p> <p>Results</p> <p>In order to develop the high-accuracy model, we focus on some possible aspects concerning the prediction performance, including the impact of interior residues, different contributions of adjacent residues, and the imbalanced data which contain much more non-epitope residues than epitope residues. In order to address above issues, we take following strategies. Firstly, a concept of 'thick surface patch' instead of 'surface patch' is introduced to describe the local spatial context of each surface residue, which considers the impact of interior residue. The comparison between the thick surface patch and the surface patch shows that interior residues contribute to the recognition of epitopes. Secondly, statistical significance of the distance distribution difference between non-epitope patches and epitope patches is observed, thus an adjacent residue distance feature is presented, which reflects the unequal contributions of adjacent residues to the location of binding sites. Thirdly, a bootstrapping and voting procedure is adopted to deal with the imbalanced dataset. Based on the above ideas, we propose a new method to identify the B-cell conformational epitopes from 3D structures by combining conventional features and the proposed feature, and the random forest (RF) algorithm is used as the classification engine. The experiments show that our method can predict conformational B-cell epitopes with high accuracy. Evaluated by leave-one-out cross validation (LOOCV), our method achieves the mean AUC value of 0.633 for the benchmark bound dataset, and the mean AUC value of 0.654 for the benchmark unbound dataset. When compared with the state-of-the-art prediction models in the independent test, our method demonstrates comparable or better performance.</p> <p>Conclusions</p> <p>Our method is demonstrated to be effective for the prediction of conformational epitopes. Based on the study, we develop a tool to predict the conformational epitopes from 3D structures, available at <url>http://code.google.com/p/my-project-bpredictor/downloads/list</url>.</p

Periodic behaviours in a digital filter with Two's complement arithmetic

Abstrac

Domain of attraction of hysteresis-series based chaotic attractors

This paper discusses the domain of attraction and its sensitivity for a class of chaotic attractors generated by using second-order linear systems with hysteresis-series. It is found that the domain of attraction of the chaotic attractors is determined by an unstable limit cycle. The chaotic dynamical behaviors are demonstrated by using the Poincaré map. The sensitivity of the domain of attraction with respect to the system parameters is studied and some simulation results are presented

Fault location in power distribution networks using sinusoidal steady state analysis

This paper proposes a fault location method based on sinusoidal steady state analysis which can locate the single phase-to-ground short-circuit fault with single-ended measurement in an overhead three-phase electric power distribution lines. By measuring and calculating certain fundamental parameters of the system as well as the voltages and currents at the sending-end, which contain corresponding fault information, the location and resistance of fault candidates can be determined by solving nonlinear distributed-parameter equations. Physical model experiments show that this method performs well

n-scroll chaotic oscillators by second-order systems and double-hysteresis blocks

A new circuit design for generating n-scroll chaotic oscillators using a linear second-order unstable system with double-hysteresis series is proposed. The hysteresis series is realised by building blocks. With this proposed scheme, the n-scroll chaotic attractors can be easily generated along the directions of the system state variables

Generation of multi-scroll chaos using second-order linear systems with hysterresis

This paper proposes a method of generating multi-scroll chaos using second-order linear systems with a hysteresis series. It shows that multi-scroll chaos can be produced in any direction in the phase plane. Furthermore, two-dimensional multi-scroll chaos can be generated as well. Both computer simulations and circuitry implementation have verified the multi-scroll chaos generation scheme

Domain of attraction of hysteresis-series based chaotic attractors

This paper discusses the domain of attraction and its sensitivity for a class of chaotic attractors generated by using second-order linear systems with hysteresis-series. It is found that the domain of attraction of the chaotic attractors is determined by an unstable limit cycle. The chaotic dynamical behaviors are demonstrated by using the Poincaré map. The sensitivity of the domain of attraction with respect to the system parameters is studied and some simulation results are presented

n-scroll chaotic oscillators by second-order systems and double-hysteresis blocks

A new circuit design for generating n-scroll chaotic oscillators using a linear second-order unstable system with double-hysteresis series is proposed. The hysteresis series is realised by building blocks. With this proposed scheme, the n-scroll chaotic attractors can be easily generated along the directions of the system state variables