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Background Macro-reentrant atrial tachycardias (MATs) are a common complication after cardiac valve surgery. The MAT types and the effectiveness of MAT ablation might differ after different valve surgery. Data comparing the electrophysiological characteristics and the ablation results of MAT post-tricuspid or mitral valve surgery are limited. Methods Forty-eight patients (29 males, age 56.1 ± 13.3 years) with MAT after valve surgery were assigned to tricuspid valve (TV) group (n = 18) and mitral valve (MV) group (n = 30). MATs were mapped and ablated guided by a three-dimensional navigation system. The one-year clinical effectiveness was compared in two groups. Results Nineteen MATs were documented in TV group, including 16 cavo-tricuspid isthmus (CTI)-dependent AFL and 3 other MATs at right atrial (RA) free wall, RA septum and left atrial (LA) roof. Thirty-nine MATs were identified in MV group, including15 CTI-dependent AFL, 8 RA free wall scar-related, 2 RA septum scar-related, 8 peri-mitral flutter, 3 LA roof-dependent, 2 LA anterior scar-related, and 1 right pulmonary vein-related MAT. Compared with TV group, MV group had significantly lower prevalence of CTI-dependent AFL (38.5% vs. 84.2%), higher prevalence of left atrial MAT (35.9 vs.5.3%) and higher proportion of patients with left atrial MAT (40 vs. 5.6%), P = 0.02, 0.01 and 0.01, respectively. The acute success rate of MAT ablation (100 vs. 93.3%) and the one-year freedom from atrial tachy-arrhythmias (72.2 vs. 76.5%) was comparable in TV and MV group. No predictor for recurrence was identified. Conclusion Although the types of MATs differed significantly in patients with prior TV or MV surgery, the acute and mid-term effectiveness of MAT ablation was comparable in two groups. Trial registration: This study was registered as a part of EARLY-MYO-AF clinical trial at the website ClinicalTrials. gov (NCT04512222).

By filling the liquid crystal (LC) in the air holes of a photonic crystal fiber (PCF) with 8 mm length, a compact multi-band thermal optical switch is proposed here including two important telecommunication band, i.e., 1265 to 1317 nm and 1508 to 1568 nm. Within the bandwidth, the extinction ratio can be as high as 30 dB. Under the combined action of the bandgap-guiding mechanism and the interference effect, a temperature change of only 1 °C after clearing temperature ( Tc ) of the LC induces multi-band thermal optical switch of the LC-filled PCF. It is also noted that the transmission spectrum of the LC-filled PCF is quite sensitive to the ambient temperature. The consequent thermal sensitive is 3.9 nm/°C, making it a very good candidate for monitoring the temperature herein.

It is still a challenging task to segment ultrasound medical images automatically and accurately because of the poor quality of images. To address these problems, a two-stage automatic segmentation scheme based on local entropy and a proposed active contour model for ultrasound images are put forward in this paper. First, a new region-based active contour model in the level set formulation, driven by global and local intensity information, is established for the segmentation. Furthermore, for automatically segmenting the ultrasound images, a coarse segmentation is performed utilizing local entropy information of the ultrasound images, then the coarse segmentation result is used as the initial value of the explicit segmentation based on the proposed model. Several experiments on real ultrasound images demonstrate that the proposed method outperforms other methods on both visual perception and objective evaluation metrics.

Background: Catheter ablation for parahisian ventricular arrhythmias (PHVA) is technically challenging and associated with risks of atrioventricular block (AVB). We developed a stepwise approach to improve the efficacy and safety of PHVA ablation. Methods: Forty-three patients (26 males; average age 65.8 ±10.4 years) with PHVAs were enrolled. A stepwise approach comprising differential electrocardiogram, sequential mapping and ablation beneath/above the septal leaflet of the tricuspid valve (SLTV) and at the neighboring/contralateral regions (the aortic root and sub-aortic valve region) was applied for PHVA. The effectiveness and safety of the stepwise approach was evaluated at the end of one year’s follow-up. Results: Sequential ablation beneath the SLTV (B-SLTV) succeeded in 24 (66.7 %) of 36 with right PHVA and ablation above the SLTV succeeded in 6 of the remaining12 with failed B-SLTV ablation. Target-His bundle (HB) distance > 4.5 mm significantly predicted successful right PHVA ablation (OR 1.703; 95% CI 1.084-2.676, P=0.02). “Seeming” right PHVA by electrocardiogram in 4 and apparent left PHVA in 3 was successfully ablated at the sub-aortic parahisian region. At the end of one year’s follow-up, 27 (75%) of 36 patients with right PHVA and 6 (85.7%) of 7 patients with left PHVA were free of PHVA recurrence off anti-arrhythmic drugs. The total success rate was 76.7% by using the stepwise approach for PHVA. One patient with A-SLTV ablation underwent pacemaker implantation due to complete AVB. Conclusions: The stepwise approach was effective and safe for treating PHVA. The target-HB distance was a significant predictor for right PHVA ablation

The images obtained by a large optical detection system (>500 mm) are always blurred by atmospheric turbulence. To address this blurring, an adaptive optical system is urgently needed. Here, a 1.3 m vehicle-based adaptive optical system (VAOS), located on the Nasmyth focus, is investigated. A two-grade tip/tilt steering mirror is used to eliminate tracking jitter and atmospheric tipping error. Pupil matching and cooperation between the deformable mirror and the wavefront sensor are adopted to achieve high-order aberration measurement and correction via closed-loop correction and to allow the telescope to obtain high-quality imaging. For different seeing conditions and site locations, the VAOS achieves the sensing over the wavelength range from 0.5 μm to 0.7 μm using a Shack-Harmann wavefront sensor and the correction with a 97-unit deformable mirror for an imaging spectrum range from 0.7 μm to 0.9 μm. Moreover, the maximum detection capability of the system is greater than a visual magnitude of 5, and the angular imaging resolution is better than 0.3″.

Due to the abundant noise, blurry boundaries, and intensity inhomogeneities present in ultrasound (US) images, it is a difficult task to segment US images accurately. In this paper, we propose a novel active contour method that combines global and local region information to achieve this task. The global information can segment US images with noise and blurry boundaries; while the local information can settle the intensity homogeneities of images. The proposed method can be directly applied to synthetic, real, and US-images segmentation. Results demonstrate the superiority of the proposed method over other representative algorithms. Moreover, we also extend the proposed method to vector-valued images. Experiments are performed to testify the feasibility of the method, and the proposed vector-valued idea can be applied to the medical co-segmentation in the future.

The safety is one of the persisting concerns related with Lithium-ion (Li-ion) batteries, among which the internal short-circuit is the most dangerous abusive situation and has always been the root cause for several catastrophic accidents in recent years. In this work, a 3D-layered electrochemical-thermal coupled model is employed to investigate the nail-penetration process in a Li-ion cell. The model is based on multilayer construction of a cell, and an effective strategy to evaluate the short-circuit area equivalent resistance (i.e. the equivalent resistance of short-circuit area that is caused by nail-penetration) during the penetration process is proposed. The developed model is proved to have capability of estimating the thermal runaway time, as well as the temperature distribution during nail-penetration process. It is also found that the active material loss during the nail-penetration process can be reconstructed by utilizing the developed model, which could provide understandings about the side reactions inside the cell during the nail-penetration process. The present study provides some insights about the nail-penetration process, and can be treated as a useful tool that helps the design of Li-ion cells for improving safety.

In the manufacturing process of ternary cathode material, batching, mixing, loading and sintering procedures play decisive roles on product quality, and data generated by these procedures are collected by the manufacturing process of ternary cathode material. However, data of the process are heterogeneous and have different properties, and sampling of key quality variables is difficult. On this basis, on-line evaluation on product quality is hard. In this paper, a data fusion based online product quality evaluation method for the ternary cathode material is proposed. Data is collected from an enterprise manufactures ternary cathode material. Then, to establish the model between the extracted data features and the key quality variables such as particle size and surface-free lithium content, a semi-supervised double-weighted probabilistic principal component regression is proposed. After that, a distance cost index is brought to cluster and grade the two quality variables, which are predicted by the semi-supervised model. Therefore, the on-line evaluation of product performance is achieved by setting rule table in accordance with production experience. Finally, based on data collected from an enterprise manufactures ternary cathode material, the proposed method is verified to be effective and accurate.

In recent years, new preparation technologies of ultra-hydrophilic TiO2 films have emerged in an endless stream, such as spray pyrolysis, electrostatic spinning, spray printing, micro-arc oxidation, pulsed laser deposition, atomic force deposition, ion beam deposition, etc. These new preparation technologies are able to control the surface chemical composition and surface structure of the thin film more precisely and to prepare the ideal superhydrophilic TiO2 coating. Among them, the rf sputtering method has important research significance for the repair and maintenance of TiO2/SiO2 composite coating. Nano TiO2 has excellent photocatalytic activity and superhydrophilicity, making it an important material for the preparation of high self-cleaning superhydrophilic coatings. However, the application of TiO2 photocatalysis requires UV light, and there is less than 5% UV light in sunlight, so the application of TiO2 photocatalytic performance is greatly limited. In addition, the surface hydrophilicity of TiO2 under light also has great problems. Therefore, improving the surface hydrophilic durability of TiO2 has become a key research point.

The core of environmental pollution detection is quartz crystal microbalance and data acquisition circuit. Under certain conditions, when the quartz crystal vibration surface adsorbs other substances, the natural frequency of quartz crystal vibration changes with the size of adsorption mass, and the frequency is converted into identifiable micro-mass data through the data acquisition circuit. This project USES quartz crystal to detect environmental pollution.

The underlying neural cognitive basis of brain-computer interfaces (BCIs) can be revealed by eventrelated potentials (ERPs) analysis, which provides another way of perceiving the extraordinary advancements in the BCI field. However, the stimulus onset asynchronies in BCIs are far shorter than those in traditional ERP studies. Moreover, strong periodic disturbances can be observed in averaged BCI signals; these cause difficulties in evaluating ERP component parameters such as amplitudes and latencies, which are required for ERP analysis. The mechanisms of such disturbances, as well as the methods to suppress them, are still unknown in the literature. In this study, an ERP signal isolation model of a BCI was built, which demonstrated that the overlapping effect of ERP components contributed to the periodic disturbances. To isolate ERP components from the contaminated signals, a Toeplitz method and difference-wave method were further proposed for the solution of the model. Experimental results showed that, by using the Toeplitz method, ERP components could be recovered from the averaged signal corresponding to the non-targets of the BCI; meanwhile, the difference wave exhibited a strong ability to suppress the overlapping effect, and ERP signals with relatively flat baselines could be obtained. These results validated the rationality of the proposed model. The study provides grounds for the explanation and suppression of the periodic disturbances in ERP analyses, while providing reasonable support for cognitive research of BCI.

We extend the bearing estimation method for noncircular signals to the impulsive noise scenario which can be modeled as a complex symmetric alpha-stable (SαS) process. We define the extended covariation based matrix of the sensor outputs and show that it can be applied with subspace techniques to extract the bearing information from noncircular sources. Comprehensive simulations demonstrate that the proposed direction finding algorithm outperforms the traditional NC-MUSIC algorithm in the presence of a wide range of impulsive noise environments.

Negative index material is one of wide research objects because of its unique characteristics,especially perfect imaging of photonic crystal slab.Silicon is a kind of the most widely applied materials in the integrated optical field because of its physical properties.In this paper,Si cylindrical rods are designed into hexagonal pattern in air to build a 2D photonic crystals flat.Band structure of this photonic crystals is calculated by the plane wave expansion method and the finite difference time domain method is used to simulate the effect on imaging when the surface structure of photonic crystals flat is changed.The simulation results show that photonic crystals slab can still image but image intensity will change by changing the both outermost radius or shifting outermost layer column laterally as photonic crystal slab equivalent refractive index is-1.And the position of image change and it changes accord with the classic Veselago relation of photonic crystal imaging as the surface structure of photonic crystals slab is changed in a certain range.But the phase difference of image and source will be 180° if the surface changes beyond this range and at the same time the image position will change sharply and the source and image will go against the Veselago relation.From the results it can be included that it can change the image intensity,position and phase effectively by changing the surface structure of photonic crystal slab.

The crash box of vehicle plays an important role in absorbing energy during collision. However, the crashworthiness optimization problem is nonlinear which means the relationship between the response and design variables is implicit. This paper constructed a response surface model instead of original model. Meanwhile, uniform design has been taken to select sampling points uniformly. Then PSO method was used to optimize the approximate model with high precision. Finally, the optimization results show that the crashworthiness of structure has enhanced and provide a guide for practical application of crashworthiness design.

mage of objects is inevitably encountered by space-based working in the atmospheric turbulence environment, such as those used in astronomy, remote sensing and so on. The observed images are seriously blurred. The restoration is required for reconstruction turbulence degraded images. In order to enhance the performance of image restoration, a novel enhanced nonnegativity and support constants recursive inverse filtering(ENAS-RIF) algorithm was presented, which was based on the reliable support region and enhanced cost function. Firstly, the Curvelet denoising algorithm was used to weaken image noise. Secondly, the reliable object support region estimation was used to accelerate the algorithm convergence. Then, the average gray was set as the gray of image background pixel. Finally, an object construction limit and the logarithm function were add to enhance algorithm stability. The experimental results prove that the convergence speed of the novel ENAS-RIF algorithm is faster than that of NAS-RIF algorithm and it is better in image restoration.

An improved mixed cryptosystem is presented by combining both random phase encoding technique based chaos and public key cryptography. The scheme provides not only good robustness of random phase encoding technique, but also a new solution of key distribution for symmetric cryptography algorithms. In additions, computer simulation is illustrated in detail. The tolerance to data loss of the encoded barcode is also studied particularly. The results show that the presented encoding method has advantage of robustness and high security, and very convenient to be popularized in practice.

This paper presents a tumor detecting system that allows interactive 3D tumor visualization and tumor volume measurements. An improved level set method is proposed to automatically segment the tumor images slice by slice. PET images are used to detect the tumor while CT images make a 3D representation of the patient's body possible. An initial slice with a seed within the tumor is firstly chosen by the operator. The system then performs automatically the tumor volume segmentation that allows the clinician to visualize the tumor, to measure it and to evaluate the best medical treatment adapted to the patient.

In this paper we propose the analogy measurement of two random variables, and discuss the principle of maximizing nongaussianity of observed data to estimate independent components sequentially based on unsupervised learning neural network. We also prove the non-polynomial moment theorem in a generalized scheme, and reveal the feasibility that replaces the analogy measurement by the expectation of a non-quadratic smooth even function based on the theorem. A formula to compute the sign of above algorithm is given, which overcomes the contradiction between the objective function and the sign computation formula.

The observed object images are seriously blurred because of the influence of atmospheric turbulence. The deconvolution is required for object reconstruction from turbulence degraded images. The wavelet transform provides a multiresolution approach to image analysis and processing. We consider a wavelet-based adaptive edge-preserving regularization deconvolution (WbARD) scheme for image restoration problems. This is accomplished by first casting the classical image restoration problem into the wavelet domain. We consider the behavior of the blur operator in the atrous wavelet domain. Then, we are able to adapt quite easily to scale-varying and orientation-varying features in the image while simultaneously retaining the edge preservation properties of the regularization. Experimental results show that the WbARD algorithm produces good performance in comparison to standard direct restoration approaches for turbulencedegraded images.

In this paper, a computer-aided diagnostic (CAD) system for the classification of rat liver lesions from MR imaging is presented. The proposed system consists of two modules: the feature extraction and the classification modules. 40 rats are used for hepatocellular carcinoma (HCC) induction with Diethylnitrosamine via drinking water. After Resovist is administrated by tail vein the animals are scanned by a 1.5-T MR scanner with T2-weighted FRFSE sequence. SPIO-enhanced images of 106 nodules (RNs(:) 24, HCCs: 82) are acquired, and 161 regions of interest (ROIs) are taken from the MR images .Six parameters of texture characteristics including Angular Second Moment, Contrast, Correlation, Inverse Difference Moment, Entropy, and Variance of 161 ROIs are calculated and assessed by gray-level co-occurrence matrices, then fed into a BP neural network (NN) classifier to classify the liver tissue into two classes: cirrhosis and HCC. Difference of each texture parameter between cirrhosis and HCC group is significant. The accuracy of classification of HCC nodules from cirrhosis is 91.67%. It indicates the ANN classifier based on texture is effective for classifying HCC nodules from cirrhosis on rat SPIO-enhanced imaging.

Evoked potential (EP) signals have been widely used to quantify neurological system properties. Delay in EP signals latency may be linked to neurological injuries. For abnormal cases where noises in EP signals usually appear impulsive, a novel robust approach, covariation correlation algorithm, is proposed to estimate EP latency delay based on fractional lower order statistics (FLOS) under alpha-stable distribution noise. Firstly, the auto-covariation of reference signal and cross-covariation between reference and detected signals are computed. Secondly, correlation between these two covariations series is calculated. Finally, the estimation value of EP latency delay is obtained from location of this correlation peak Simulation studies show that the estimation precise of this novel algorithm is higher than that of correlation or covariation algorithms especially under lower mixed signal noise ratio (MSNR).

It is very difficult to describe a nonstationary random signal, to say nothing of processing it effectively. In recent years, the time-varying parametric model, especially, time-varying auto-regressive parametric model has been used widely. It is well known that a wavelet neural network has very good performance on function approximation. In this paper, the wavelet neural network is introduced into the time-varying auto-regressive parametric model, so a new time-varying auto-regressive parametric model based on wavelet neural network is presented. At the same time, a new algorithm for model parameters estimate is also presented. A few simulations indicate that the performance of the new time-varying auto-regressive parametric model is better than the old one.

This paper analyzes the Kurtosis based ICA method, and presents the geometrical explanation of its principle. Through the analysis of ICA solution process, this paper also explains the reasons for the indeterminacy and probabilistic property of the ICA solution. The analytical results and conclusions can be applied to the studies of other ICA methods.

This paper aims at designing a 2D photonic crystal (PC) with negative refractive index close to -1. Plane wave expansion method (PWEM) is used to obtain the band diagram and its equal-frequency surface (EFS). And the finite difference time domain (FDTD) simulation method is also used to analyze the equivalent refractive index of the PC. The results show the equivalent refractive index of the PC close to -1 within a certain frequency band. A super-lens is formed by this photonic crystal, which can form a non-near-field image. Moreover, the super-lens has the capability of sub-wavelength imaging with its effective index close to -1.