Study of features based on nonlinear dynamical modeling in ECG arrhythmia detection and classification

We present a study of the nonlinear dynamics of electrocardiogram (ECG) signals for arrhythmia characterization. The correlation dimension and largest Lyapunov exponent are used to model the chaotic nature of five different classes of ECG signals. The model parameters are evaluated for a large number of real ECG signals within each class and the results are reported. The presented algorithms allow automatic calculation of the features. The statistical analysis of the calculated features indicates that they differ significantly between normal heart rhythm and the different arrhythmia types and, hence, can be rather useful in ECG arrhythmia detection. On the other hand, the results indicate that the discrimination between different arrhythmia types is difficult using such features. The results of this work are supported by statistical analysis that provides a clear outline for the potential uses and limitations of these features.     

Resistivity dependence of minority carrier lifetime and cell performance in p-type dendritic web silicon ribbon

This study shows that the bulk lifetime in 95 μm thick p-type dendritic web silicon solar cells is a strong function of bulk resistivity. The higher the resistivity, the greater the bulk lifetime. This behavior is explained on the basis of dopant–defect interaction, which increases the lifetime limiting trap concentration with the addition of dopant atoms. Model calculations show that in the absence of doping dependence of bulk lifetime (τ), 2 Ω cm web should give the best cell efficiency for bulk lifetimes below 30 μs. However, strong doping dependence of bulk lifetime in p-web cells shifts the optimum resistivity from 2 to 15 Ω cm. Bulk lifetime in the as-grown web material was found to be less than 1 μs for all the resistivities. After the cell processing which involves phosphorus gettering, aluminum gettering, and SiN induced hydrogen passivation of defects, the bulk lifetime increased to 6.68, 11, 31 and 68.9 μs in 0.62, 1.37, 6.45 and 15 Ω cm p-type web material, respectively. Therefore, cell process induced recovery of lifetime in web is doping dependent, which favors high resistivity. Solar cells fabricated on 95 μm thick web silicon by a manufacturable process involving screen-printing and belt-line processing gave 14.5% efficient 4 cm² cells on 15 Ω cm resistivity. This represents a record efficiency for such a thin manufacturable screen-printed cell on a low-cost PV grade Si ribbon that requires no wafering or etching.     

A framework for predictive modeling of anatomical deformations

A framework for modeling and predicting anatomical deformations is presented, and tested on simulated images. Although a variety of deformations can be modeled in this framework, emphasis is placed on surgical planning, and particularly on modeling and predicting changes of anatomy between preoperative and intraoperative positions, as well as on deformations induced by tumor growth. Two methods are examined. The first is purely shape-based and utilizes the principal modes of co-variation between anatomy and deformation in order to statistically represent deformability. When a patient's anatomy is available, it is used in conjunction with the statistical model to predict the way in which the anatomy will/can deform. The second method is related, and it uses the statistical model in conjunction with a biomechanical model of anatomical deformation. It examines the principal modes of co-variation between shape and forces, with the latter driving the biomechanical model, and thus predicting deformation. Results are shown on simulated images, demonstrating that systematic deformations, such as those resulting from change in position or from tumor growth, can be estimated very well using these models. Estimation accuracy will depend on the application, and particularly on how systematic a deformation of interest is.     

An energy-aware forecasting-based framework using a novel moving coordinate scheme for sensor real-time communications

Wireless Networks - In order to save on the energy expended by a sensor node in its communications with the sink, forecasting-based frameworks have recently been proposed. Those frameworks...     

Using Stochastic Differential Equation for Verification of Noise in Analog/RF Circuits

Today’s analog/RF design and verification face significant challenges due to circuit complexity, process variations and short market windows. In particular, the influence of technology parameters on circuits, and the issues related to noise modeling and verification still remain a priority for many applications. Noise could be due to unwanted interaction between the circuit elements or it could be inherited from the circuit elements. In addition, manufacturing disparity influence the characteristic behavior of the manufactured circuits. In this paper, we propose a methodology for modeling and verification of analog/RF designs in the presence of noise and process variations. Our approach is based on modeling the designs using stochastic differential equations (SDE) that will allow us to incorporate the statistical nature of noise. We also integrate the device variation due to 0.18μ m fabrication process in an SDE based simulation framework for monitoring properties of interest in order to quickly detect errors. Our approach is illustrated on nonlinear Tunnel-Diode and a Colpitts oscillator circuits.     

Formamide driven synthesis of well-aligned ZnO nanorod arrays on glass substrate

A cost effective, low-temperature approach has been developed for the large-area deposition of ZnO nanorod/nanotube arrays on a ZnO coated glass substrate by the natural oxidation of zinc metal in formamide/water mixtures. The two-step seed deposition and wet-chemical approach exhibited well-controlled growth of highly oriented and densely packed ZnO nanorod/nanotube arrays with large-area homogeneity and uniform morphologies. In order to investigate the quality and alignment of ZnO nanorod arrays grown on the ZnO seed layer coated substrate, three different methods of ZnO coating have been deposited by ultrahigh vacuum evaporation system, DC sputtering and RF sputtering, respectively. Our results showed that the ZnO seed layer grown by RF sputtering resulted in high quality ZnO nanorod arrays.     

ZF and MMSE Detectors Performances of a Massive MIMO System Combined with OFDM and M-QAM Modulation

Wireless Personal Communications - This paper presents a least squares channel estimation (LSCE) in the UpLink transmission for a Massive MIMO systems in 5G wireless communications, combined with...     

Best Minimum Summation Scheduler for Long Term Evolution

Resource scheduling in Long Term Evolution (LTE) is an open and rising issue. It has an enormous impact on the entire system performance. Due to the nature of LTE system, the scheduler has to be designed carefully. It has to overcome many challenges such as limited processing time and the high dynamic behavior. This paper proposes a novel scheduling policy for the MAC layer in LTE called the Best Minimum Summation (BMS). The main aim of this scheduling policy is to achieve high performance with low complexity. Three sub-schedulers have been developed. Each one of these schedulers deals with scheduling table in different dimension. The first one operates on the scheduling table through the user dimension (BMS.UE); while the second one operates on the scheduling table through the resource block dimension (BMS.RB). The third scheduler operates on the scheduling table correlating both of these dimensions (BMS.2D). All of the proposed solutions were intensively evaluated in a system level simulator. Three performance metrics were used which are throughput, error rate and fairness. The results have shown that the ability of the BMS.UE scheduler to outperform other existing schedulers of LTE.