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Atrial fibrillation (AF) is one of the most common arrhythmias, associated with high morbidity, mortality, and healthcare costs, and it places a significant burden on both individuals and society. Anti-arrhythmic drugs are the most commonly used strategy for treating AF. However, drug therapy faces challenges because of its limited efficacy and potential side effects. Catheter ablation is widely used as an alternative treatment for AF. Nevertheless, because the mechanism of AF is not fully understood, the recurrence rate after ablation remains high. In addition, the outcomes of ablation can vary significantly between medical institutions and patients, especially for persistent AF. Therefore, the issue of which ablation strategy is optimal is still far from settled. Computational modeling has the advantages of repeatable operation, low cost, freedom from risk, and complete control, and is a useful tool for not only predicting the results of different ablation strategies on the same model but also finding optimal personalized ablation targets for clinical reference and even guidance. This review summarizes three-dimensional computational modeling simulations of catheter ablation for AF, from the early-stage attempts such as Maze III or circumferential pulmonary vein isolation to the latest advances based on personalized substrate-guided ablation. Finally, we summarize current developments and challenges and provide our perspectives and suggestions for future directions.

BACKGROUND The treatment protocol for children with developmental dysplasia of the hip (DDH) is routinely adjusted by assessing the hip reduction after 3 weeks of Pavlik harness treatment. However, there is a high risk of failure and complications in the treatment adjustment. The aim of this study was to explore the value of ultrasound features in predicting the treatment outcome of Pavlik harness after 3 weeks in DDH children. METHODS A total of 215 DDH children were recruited and the demographics and the changes of ultrasound features [α and β angle and femoral head coverage (FHC)] during the Pavlik harness treatment were recorded. The children were divided into the success group and the failure group according to the reduction outcome after 3 weeks. Univariate and multivariate analyses were performed to analyze the independent predictors for the treatment outcome. Repeated-measures analysis of variance was used to compare the changes of ultrasound features between the two groups during the treatment. Receiver operating characteristic (ROC) curves were plotted to analyze the predictive accuracy of the ultrasound features. RESULTS Graf type III (P=0.036), bilateral dislocation (P=0.031), and age at diagnosis (P=0.021) were associated with an increased risk of Pavlik harness failure in the multivariate analysis. The changes in α and β angle and FHC were generally greater in the success group than in the failure group. The α angle and FHC were larger in the success group, while the β angle was larger in the failure group (P

This paper proposes an active resonance circuit based on multiple series gaps (MSG) with voltage-dividing network and self-charging trigger device. The working principle of active resonance circuit, MSG, and triggering device is described in detail. To determine the optimal parameter setting of MSG, the effects of the voltage frequency, equalizing resistance, and voltage-dividing capacitance on the voltage distribution of MSG are analyzed by simulation. To realize the interrupting process of short fault current and determine the operation requirements of the main devices of precharge direct current (dc) circuit breaker, a simulation model of interrupting short fault current is performed. Furthermore, an experiment of four-series gaps is presented to verify the turn-on characteristic of the MSG and an experiment of artificial current zero is set up to testify the feasibility of the active resonance circuit. The simulation and experimental results show that the active resonance circuit proposed in this paper can generate an artificial zero current and is suitable for precharge dc circuit breaker.

The impedance of a horizontal Extremely low frequency (ELF) line-current antenna is studied. A new analytic expression for calculating a grounding resistance in any shape of ground screen in a two-layer earth is proposed, model adapted to a bed-rock with high resistivity. Its calculated accuracy has a significant improvement compared with previous literature. The radiation resistance of an ELF line-current antenna over inhomogeneous anisotropic ground is researched. The effect of anisotropy of the ground conductivity on radiation efficiency of an ELF line-current antenna is analyzed. The obtained results have important purpose in engineering design of ELF horizontal antenna path.

A simple expression is presented to quickly estimate specific attenuation coefficient due to fog within the ranges of 100~300GHz and -8~20°C based on the Rayleigh approximation which is not very convenient. To evaluate the expression’s estimation performance, the Pearson correlation coefficient (PCC) and maximal absolute value of the relative errors (MAVRE) are calculated. The maximum value of PCC is 1 and it reflects the fitting performance of an empirical expression. MAVRE denotes the largest deviation between a set of estimated values and corresponding theoretical values. Calculations show the PCC and MAVRE of the proposed expression are 0.99985 and 4.162%, respectively. Furthermore, a comparison analysis shows that the new expression has much better estimation performance than other two empirical expressions: the modified Mao expression and the Zhao expression.

Robot soccer is an effective platform which is used to validate techniques such as artificial intelligence. Due to the limitations of a single robot, complex tasks on pitch often need to be completed through coordination of multiple robots. The purpose of this paper is to realize the information transfer between robots and thus to achieve information sharing by designing the network communication system among robots, as well as to provide forceful support for robots' decision-making and multi-robots cooperation. Meanwhile, the ant colony algorithm,which comes after the realization of robot communication system, is introduced to solve the problem existed in multiple-robots coordination. Experimental results show that the communication system in this paper can effectively fulfill information transfer between robots and has laid a good foundation for cooperation of robots.

In this paper, we present a high-voltage electric-spark bubble-generating method which can generate a bubble with its maximum radius reaching up to ∼35 mm at a room pressure. Vertical migration and clear liquid jet inside the bubble are captured by a high speed photography. With this method, a series of experiments on bubbles collapse above a solid boundary are carried out under different non-dimensional standoff distances γ (= s/Rm, where s is the vertical distance from the bubble center to the solid boundary and Rm denotes the maximum bubble radius). It is found when bubble is extremely close to the solid boundary (γ < 0.6), the lower surface of the bubble will cling to the solid boundary, which causes the cone-shaped liquid jet to impact on solid boundary directly without buffering of the water layer. With the increase of γ, the bottom of the bubble is gradually away from the solid boundary with an increasing curvature, but the jet inside the bubble remains conical all along. The speed of the jet tip and the migration of the bubble top are also discussed subsequently, aiming to provide a reference for the numerical study. Finally, the critical value of γ is investigated, at which the effect of the buoyancy will compensate the attraction of the solid boundary when the buoyancy parameter of bubble is bout 0.06.Copyright © 2016 by ASME

This research analyses on the various design elements and the evaluation of levels through the visual level of the theory of product image for the machine tools. The study captures the image elements of machine tools through the way of qualitative perception and the quantitative analysis, forming the framework of product design to extract the product image model for more direct comparison and effective research. This thesis strengthens the brand building of machine tools from the point of product image design, studies in close connection with the characteristics of the industry and products, and makes a more specific and practical significance to the design theory for the specific product design, which is useful to clear the direction of product design for the machine tools companies, and thus shaping the product-based brand and enhancing the overall national level of competition in the equipment manufacturing industry.

Aimed at the situation that the welding voltage is easy to be disturbed by the voice outside, median filtering and average filtering are adopted to filtering signal of the voltage the rotating arc sensor collected in this paper. They can make the voltage waveform get obvious improvement. In order to get information which the welding torch deviated the welding seam more accurately, left and right integration, Characteristic Harmonics method and welding torch deviation recognition algorithm are adopted to identify the deviations in this paper. Finally compare the two kinds of identification deviation methods and obtain better welding torch deviated information.

Compared with the existing arc sensors, high speed rotating scanning arc sensor has up to 50 HZ rotating speed, and it can be much more compact, cheaper and more sensitive. The arc welding robot can weld for three movement types using the high speed rotating scanning arc sensor. Weld shaping and mechanical properties for three movement styles of arc welding robot torch are studied. The macrostructure appearance characteristics of mild steel bead-on-plate weld seam section and fillet weld seam section are analyzed. Experimental researches are undertaken in tension and bending test.The results show that the weld shaping of rotating arc weld for bead-on-plate weld and fillet weld is better than that of linear motion arc welding and oscillating arc welding. This investigation will provide the theoretical basis for the advantage and choice of three arc movement styles in the practical production.

Based on the research of dynamic characteristics of axial flow blood pump which is drove by the large gap magnetic drive system, a serial communication between PC and AT89C51 to realize the real-time process of the blood pump acceleration is proposed. The acceleration control parameters are decided by the analysis of blood pump speed control mechanism. As a result, Previous, the previous program which is modified to change the control parameters repeatedly is saluted by building the PC model. At the same time, the control of multiple control parameters could be achieved when a program on the microcontroller is addressed. What’s more, the more experiments will be realized, to provide more conveniences to the system.

Based on the single chip microcomputer (SCM) control theory, the control circuit of magnetic driving system of axial flow blood pump is designed. For the easy damage of TIP 122, which is used as the power switch of control circuit, RC snubber circuit is designed by analysis and experiments. And then an optimal matching of the key parameters is obtained to solve the security problem of the TIP 122. The experimental results show that the RC snubber circuit can improve the reliability and stability of the driving system, and to provide an experimental foundation for the further studies.

Synthetic problem of variable structure control (VSC) for linear singular system with input and state time-delays is studied. Firstly, the original system with both input and state time-delays is written into a form without time-delay by a linear transformation. Secondly, the system without time-delay is decomposed into two low dimensional subsystems by a restricted system equivalent decomposed method. Thirdly, the quadratic performance index optimal control technique is introduced to design the optimal sliding mode for the restricted equivalent subsystems. By applying reaching law approach, the selected control law ensures that the solution trajectories of the system reach the switching manifold in finite time and have low chattering in the sliding motion. Finally, a simulation example is given to illustrate the feasibility and validity of the proposed method.

When underwater explosion breaks out, usually the bubble with a radius of meters is generated. The bubble’s oscillation may cause the damage of the floating structure thereabout. In the present paper, a 3-D Boundary Element Method (BEM) model based on the potential theory is implemented to simulate the strong non-linear interaction process. The focusing problem is to track the movement of the contact line between the structure and the free surface with some degree of robustness. Although the negative mirror image model could take the free surface’s effect into consideration without catching the contact line, its assumption that the free surface be motionless wasn’t tally with the real situation to some extent. Non-linear free surface effect is simulated in this paper. By splitting the nodes, both the Direchlet and the Neumann boundary conditions will be satisfied of the nodes on the contact line. Therefore, the moving boundaries’ deformation can consistent with the actual situation well. In this paper, the authors firstly introduce a 3-D BEM model for bubble dynamics, and present a way to deal with the strongly integral for the open boundary. Then the accuracy of the model is examined in comparison with the negative mirror image model. By using the numerical model, bubble dynamics near a marine structure with varying increment’s position and weight are studied respectively. We find out that the depth and the weight of charge will affect the bubble’s shape. This paper has its implication to offer ideas on multiphase fluid interaction and the damage mechanism induced by high-pressure bubble on floating structures.Copyright © 2015 by ASME

According to the latest requirements of the advanced laser system, a 700 kA gas switch with graphite electrodes for pulsed power supply module has been developed. The paper describes the design, construction and testing of the high-current gas switch. Through the analysis of the electrodes erosion of different materials, high-density graphite is found to be suitable for electrodes of the gas switch with high current and charge transfer. A two-electrode gas switch with FRP rods and an updated gas switch using hoop type fastening method have been developed, the magnetic switch is used in the trigger circuit. Experimental results show that both the switches can conduct the current of over 700 kA and the charge transfer of more than 500 coulomb per shot.

Diffuse discharge in atmospheric air can generate extremely high power density and large-scale non-thermal plasma. An achievable method of generating diffuse discharge is reported in this paper. Based on the resonance theory, a compact high-voltage repetitive nanosecond pulse generator (HRNPG) has been developed as discharge excitation source. The HRNPG mainly consists of repetitive charging circuit, Tesla transformer and sharpening switch. With the voltage lower than 1.0 kV, the primary repetitive charging circuit comprises two fast thyristors as low-voltage switches. A spiral Tesla transformer is designed to provide a peak transformation ratio of more than 100. The HRNPG prototype is capable of generating a pulse with over 100 kV peak voltage and ~30 ns rise-time at the repetition frequency of 500 Hz. Using the copper line electrodes with a diameter of 0.4 mm, the gaps with highly non-uniform electric field are structured. With the suitable gap spacing and applied pulse, the glow-like diffuse discharge has been generated in line-type and ring-type electrode pairs. Some typical images are presented.

Repetitive pulsed power technology has been developed fast during these decades, while a small-size, compact, portable, and reliable repetitive pulsed power source has a very extensive application prospect in defense, industry, and laboratory research fields. In this paper, a compact repetitive pulsed power source based on Tesla transformer with build-in coaxial pulse forming line has been developed. The design, construction and experiment testing are presented in detail. In order to get high a couple coefficient and turns ratio, open-loop magnetic core and conic secondary turns are adopted, respectively. The maximum charging voltage of the transformer is 240 kV with transformer oil insulation while the primary circuit comprises a fast thyristor as the low-voltage switch. The weight of the device with the small-size (20×20×70mm3) is less than 30 kg. Using a gas switch without blowing, the device is capable of delivering, to a 100 ohm load, an output pulse of 150 kV in peak voltage with a rise time of 2 ns and a pulse length of 7 ns, at the repetition rate of 50Hz.

In this paper, sliding mode variable structure control for the dynamic system of knowledge workers in high-tech enterprises is given. First, the more general dynamic system on technical knowledge workers, managerial knowledge workers, marketing knowledge workers, and others in high-tech enterprises is studied. Second, the sliding mode variable structure control strategy is introduced on the basic of the reaching law and equivalent control methods, and the dynamic system of knowledge workers in high-tech enterprises is analyzed by sliding mode variable structure control. Finally, a simulation example on the sliding mode variable structure control system in a city is given. The system can reach the switching plane in finite time, and enhance the dynamic quality of the systems.

Objective: To assess the practical utility of pleural fluid carbonic anhydrase XII (CAXII) quantification for differential diagnosis of effusions. Materials and Methods: Fluid was collected prospectively from fifty patients presenting with lymphocytic pleural effusions for investigation and CAXII was quantified by ELISA. Results: Pleural fluid CAXII concentrations were significantly higher in lung cancer patients (n=30) than in tuberculous controls (n=20). The sensitivity and specificity of this biomarker were 60%and 75%, respectively. CAXII measurement was not inferior to cytological examination in the diagnosis and exclusion of pleural effusions from lung cancer patitents (sensitivity 60% vs. 57%; specificity 75% vs. 100%; positive predictive value 77%; negative predictive value 54%). In patients with negative cytology, it offered a sensitivity of 54%. Conclusions: Pleural fluid CAXII is elevated in pleural effusions from lung cancer patients. Measurement of CAXII may be used in the future as a valuable adjunct to cytology in the diagnostic assessment of patients with pleural effusions related to lung cancer, especially when cytological examination is inconclusive.

This paper introduces a method to generate large-scale diffuse plasmas by using a repetition nanosecond pulse generator and a parallel array wire-electrode configuration. We investigated barrier-free diffuse plasmas produced in the open air in parallel and cross-parallel array line-line electrode configurations. We found that, when the distance between the wire-electrode pair is small, the discharges were almost extinguished. Also, glow-like diffuse plasmas with little discharge weakening were obtained in an appropriate range of line-line distances and with a cathode-grounding cross-electrode configuration. As an example, we produced a large-scale, stable diffuse plasma with volumes as large as 18 × 15 × 15 cm3, and this discharge region can be further expanded. Additionally, using optical and electrical measurements, we showed that the electron temperature was higher than the gas temperature, which was almost the same as room temperature. Also, an array of electrode configuration with more wire electrodes had helped to prevent the transition from diffuse discharge to arc discharge. Comparing the current waveforms of configurations with 1 cell and 9 cells, we found that adding cells significantly increased the conduction current and the electrical energy delivered in the electrode gaps.

The solution resistive divider is often used considering its excellent high-frequency and withstanding voltage characteristics. This paper develops a nanosecond pulse measurement system based on the CuSO4 solution resistive divider, which can be used to measure high voltage impulses with rise time of 50 ns and amplitude of 300 kV. The low-voltage arm of the newly designed solution resistive divider is composed of noninductive metal film resistors. The newly designed resistive divider combines the advantages of the conventional solution resistive divider and metal film resistive divider. The stray parameters of the resistive divider are theoretically calculated and the circuit simulation is studied. Besides, the square wave response characteristics of the resistive divider are studied in the experiments. Considering the effect of frequency on the surge impedance of the cable, a matching cable of the same type with the transmission cable instead of a common matching resistor is used to improve the matching effects. In order to reduce the effects of electromagnetic interference on the measurement results, some shielding measures are taken. The experimental results show that the measurement system has good response characteristics in the practical application.

In room-temperature atmospheric air, the large-scale diffuse plasmas can be generated via high-voltage nanosecond pulses with short rise-time and wire electrodes. Diffuse discharge with the wire electrode length up to 110.0 cm and the discharge spacing of several centimeters has been investigated in this paper. Electrical characteristics of diffuse discharge have been analyzed by their optical photographs and measuring of the voltage and current waveforms. Experimental results show the electrode spacing, and the length of wire electrodes can influence the intensity and mode transition of diffuse discharge. The characteristic of current waveforms is that there are several current oscillation peaks at the time of applied pulsed voltage peak, and at the tail of applied pulse, the conduction current component will compensate the displacement one so that the measured current is unidirectional in diffuse discharge mode. The transition from diffuse discharge to arc discharge is always with the increasing of conduction current density. As for nanosecond pulses with long tail, the long wire electrodes are help for generating non-equilibrium diffuse plasmas.