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In this study, we propose an innovative approach that enhances the performance of the backpropagation (BP) neural network in predicting the low‐cycle fatigue life of Ti‐6Al‐4V alloy by improving the dung beetle optimization (DBO) algorithm with the maximin Latin hypercube design (MLHD) strategy. To address the challenges posed by complex geometric components under different temperature conditions, this research employs finite element simulation to expand the limited experimental dataset and utilizes these data to further guide and optimize the MLHD_DBO_BP model. Test results indicate that the proposed MLHD_DBO_BP model significantly outperforms the traditional finite element method (FEM) and other neural network models in terms of fatigue life prediction performance. This research demonstrates the effectiveness of machine learning models that combine experimental and simulation data in predicting the low‐cycle fatigue life of Ti‐6Al‐4V alloy. [ABSTRACT FROM AUTHOR]

Reliable and accurate wind-speed forecasts significantly impact the efficiency of wind power utilization and the safety of power systems. In addressing the performance enhancement of transformer models in short-term wind-speed forecasting, a multi-step prediction model based on variational mode decomposition (VMD), temporal convolutional network (TCN), and a transformer is proposed. Initially, the Dung Beetle Optimizer (DBO) is utilized to optimize VMD for decomposing non-stationary wind-speed series data. Subsequently, the TCN is used to extract features from the input sequences. Finally, the processed data are fed into the transformer model for prediction. The effectiveness of this model is validated by comparison with six other prediction models across three datasets, demonstrating its superior accuracy in short-term wind-speed forecasting. Experimental findings from three distinct datasets reveal that the developed model achieves an average improvement of 52.1% for R2. To the best of our knowledge, this places our model at the leading edge of wind-speed prediction for 8 h and 12 h forecasts, demonstrating MSEs of 1.003 and 0.895, MAEs of 0.754 and 0.665, and RMSEs of 1.001 and 0.946, respectively. Therefore, this research offers significant contributions through a new framework and demonstrates the utility of the transformer in effectively predicting short-term wind speed. [ABSTRACT FROM AUTHOR]

Knowledge tracing (KT), which aims to trace human knowledge learning process by using machines, has widely applied in online learning systems. It dynamically models student's knowledge states in relation to different learning factors through their learning interactions. Recently, KT has attracted many researches attention due to its good performance to using deep learning. Although most of KT models have shown outstanding results, they have limitations: either ignore the human cognitive law and learning behavior, or lack the ability to go deeper modeling to trace knowledge state. In this paper, we propose a deeper knowledge tracking model integrating cognitive theory and learning behavior (CLDKT). It united the advantages of memory network and recurrent neural network of the existing deep learning KT models for modeling student learning. To better implement CLDKT, we add the residual network (ResNet) to realize the deep modeling of learning behaviors. Extensive experiments on three open benchmark datasets to evaluate our model. Experimental results demonstrate that (I) CLDKT outperforms the state-of-the-art KT models on students' performance prediction. (II) CLDKT can deeper modeling to trace knowledge state owing to the ResNet import. (III) CLDKT has better interpretability and predictability, which proves the effectiveness of the knowledge tracing model integrating cognitive law and learning behavior. [ABSTRACT FROM AUTHOR]

This study introduces a GPU-based parallel computing approach that combines the phase-field model (PF) and the lattice Boltzmann model (LBM). By establishing a coupled multiphase field model incorporating physical external fields such as flow field, temperature field, and solute field, the research simulates the growth of single grains and multiple grains under the influence of natural convection. The variations in dendritic morphology, flow field, and solute field during dendritic solidification processes are observed. Initially, the study analyzes the morphology of equiaxed dendrites and the growth patterns of primary dendrites arms under natural convection conditions. The evolution of equiaxed dendrites in single grains and multiple grains under various conditions is investigated. Furthermore, the study explores the impact of different anisotropy strengths on the growth of single grains and multiple grains under natural convection. Notably, a distinct "necking" phenomenon is observed when the anisotropy strength of a single grain is 0.05. In the case of multiple grains, where competition between dendrites is present in addition to the influence of natural convection, a pronounced "necking" phenomenon is evident at an anisotropy strength of 0.03. Moreover, OpenCL parallel technology is designed on the GPU platform to accelerate the solution of the model. The parallelization of the phase-field model coupled with the LBM model on the GPU demonstrates a clear advantage. The parallel computation based on GPU not only exhibits absolute superiority but also shows more significant acceleration effects as the computational domain increases. [ABSTRACT FROM AUTHOR]

Since the dynamic characteristics of the rotor supported on active magnetic bearings (AMBs) are strongly dependent on the control strategies and control parameters, it is significant to design proper controllers for the AMBs-rotor systems. A robust proportional-differential (PD) control via eigenstructure assignment for an AMBs-rigid rotor system is proposed in this article. First, the dynamic model of the four-degree-of-freedom (4-DOF) AMBs-rigid rotor system was established and was converted into two 2-DOF models by a cross-differential feedback, which radically eliminates the coupling caused by gyroscopic effect. Then, the parametric expressions of the PD feedback matrix and the closed-loop eigenvector matrix for one of the 2-DOF models were obtained by eigenstructure assignment. In order to acquire stability and desired dynamical performance, the eigenvalues were confined in some specific regions in the complex plane. A multiobjective optimization problem was constructed to make the AMBs-rotor system not only be insensitive to the change of the bias current, but also have low amplitudes of the unbalance vibration and unbalance control currents over the full rotational speed range. The system performances corresponding to two Pareto solutions were compared in numerical simulation and experiments, and the results verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A multi-phase model was established to imitate the growth of algal and dendritic grains during directional solidification. We studied the effects of temperature on the growth of bi-crystals and quantitatively analyzed the influence of anisotropic strength, thermal gradient, and pulling velocity on the evolution of bi-crystals. The results show that both weaker anisotropy strength and smaller pulling velocity can maintain the formation of seaweed tissue. The increase in the pulling velocity can degenerate the seaweed grains into dendrites and improve the growth rate of the dendrites, which make grain B produce more spindles, thereby accelerating the elimination of grain A. The thermal gradient is inversely proportional to the average initial spacing of dendrites. When the thermal gradient is too small, dendritic dendrites produce developed secondary dendrite arms, which, in turn, develop into tertiary dendrite arms to occupy the grain boundary, accelerating the elimination of seaweed grains. In addition, the multi-phase field model is solved by using central processing unit serial computation, single MPI (message passing interface) parallel programming method calculation, and MPI+OpenMP hybrid parallel programming structure, and the relevant factors affecting the efficiency of program operation are analyzed and tested. By comparing the computational efficiency of the three methods, it can be seen that the MPI+OpenMP hybrid parallel programming technology can make full use of computing resources in the case of large computing scale, further optimize the MPI parallel model, and obtain a higher acceleration ratio. [ABSTRACT FROM AUTHOR]

In order to suppress the synchronous unbalance vibration of the active magnetic bearings (AMBs) rigid rotor system in the full rotational speed range, the polarity switching control (PSC) can effectively suppress the synchronous unbalance vibration of the AMBs-rigid rotor system before and after the rigid cylindrical mode frequency, and the impact of the switching polarity on the system was reduced by using a disturbance observer. However, considering the rigid conical mode, the PSC could not guarantee the synchronous unbalance vibration suppression of the AMBs-rigid rotor system in the full rotational speed range including the rigid cylindrical mode frequency and the rigid conical mode frequency, and the system stability also changes accordingly. This article proposes a synchronous unbalance vibration suppression method based on the four-factor PSC (4-FPSC), which adjusts four polarity factors to suppress the synchronous unbalance vibration before and after two rigid mode frequencies. Besides, the disturbance observer is also avoided. Finally, simulation and experiment results verify the 4-FPSC can effectively suppress the synchronous unbalance vibration of the AMBs-rigid rotor system in the full rotational speed range including the rigid cylindrical and conical mode frequencies. [ABSTRACT FROM AUTHOR]

In active magnetic bearings (AMBs) supported rigid rotor systems, the unbalance compensation strategy based on a notch filter was often used to suppress the synchronous unbalance vibration when the rotor operates in the steady-state rotational speed. Whereas the rotor operates in a rotational-speed range including the critical rotational speeds, conventional notch filters should be improved to suppress the unbalance vibration. In most cases, improving the structure of the notch filter, such as a cross-feedback notch filter, phase-shift notch filter, adding the polarity switch or two-stage switch, was considered to make the notch filter work in the rotational-speed range. However, the improved notch filter may affect the stability of the AMBs rotor systems and result in large vibrations when the polarity switch or two-stage switch shifts. To avoid the shortcomings of these methods, a method using a variable angle compensation algorithm was proposed to suppress the synchronous unbalance vibration in finite iterative seeking processes, directly realizing unbalance compensation according to real-time rotor position. Finally, the effectiveness of the method proposed is verified by simulation and experiment results. [ABSTRACT FROM AUTHOR]

For the unbalance vibration of the rigid rotor system on active magnetic bearings (AMBs) supported high-speed motors in the full rotational speed range, a method based on the polarity switching tracking filter (PSTF) and the disturbance observer (DO) is proposed to achieve vibration suppression. To identify the synchronous unbalance vibration, a positive polarity tracking filter and a negative one are adopted before and after the rigid critical rotational speed range, respectively. The rigid critical rotational speed is in this range whose lower/upper limit is the negative/positive polarity switching frequency. Although the PSTF can effectively reduce the rotor vibration when it rotates at subcritical rotational speed range and supercritical range, the vibration increases evidently and even destabilize the system within the rigid critical rotational speed range. It means that the PSTF cannot suppress the rotor unbalance vibration in the full rotational speed range. However, this vibration during the rigid critical rotational speed range can be considered as a kind of disturbance and the DO is adopted to observe it, then the vibration identified is compensated in the control current to reduce the rotor unbalance vibration in the rigid critical rotational speed range. Therefore, the method based on the PSTF and the DO can suppress the unbalance vibration in the full rotational speed range. Finally, simulation and experiment results demonstrate that the method proposed can effectively suppresses the synchronous unbalance vibration of the AMBs-rigid rotor system in the full rotational speed range. [ABSTRACT FROM AUTHOR]

Accurate wind speed forecast plays an important role in the safe and stable operation of large-scale wind power integrated grid system. In this paper, a new hybrid model for short-term wind speed forecasting based on hyperparameter optimization and error correction is proposed, where the forecasting period is 5, 10, and 15 min, respectively, for three sites. The empirical wavelet transform is used to decompose the original wind speed series. Then, the Elman neural network and kernel extreme learning machine, which adopt Bayesian optimization algorithm for hyperparameter optimization, are used as predictors for wind speed prediction and error processing, respectively. In addition, a new error correction model using wind speed as model input is proposed. In order to verify the performance of the proposed model, three datasets collected from different real-world wind farms in Gansu and Xinjiang were considered as a case study to comprehensively evaluate the prediction performance of ten forecasting models. The results reveal that the proposed model has higher prediction accuracy and better prediction performance than the contrast models. [ABSTRACT FROM AUTHOR]

Based on the muti-component eutectic multi-phase field model of S. G. Kim, W. T. Kim, T. Suzuki et al. [J. Cryst. Growth 261, 135–158 (2004)], the high-performance computing method of hardware and software architecture of OpenCL + graphics processing unit (GPU) was studied. Taking CBr4–C2Cl6 as an example, the evolution process of large-scale three-dimensional eutectic structure growth is realized by concurrent execution of multiple processes and multiple threads on two heterogeneous platforms of AMD and NVIDIA, respectively. The effects of different initial lamellar spacing and flow on eutectic lamellar morphology were also studied. The results show that, with the increasing of eutectic lamellar spacing, the morphology of eutectic lamellar changes are as follows: the symmetrically steady-state perpendicular to the interface is based on growth, the slightly oscillating state is unstable, and the large oscillating state is unstable; Under the condition of forced convection, the symmetrically alternating growth pattern of the original eutectic lamellar was broken, the melt flow led to the change of eutectic growth morphology, and the eutectic lamellar grew in the opposite direction of the flow. At the same computing scale, compared with the serial algorithm on the central processing unit platform, the acceleration ratio on the single GPU on the heterogeneous platform reaches 24.3 times and 21.6 times respectively, which improves the computing efficiency. At the same time, with its strong floating-point computing power to obtain more accurate simulation results and achieve the dual needs of computational efficiency and portability, it has also proven to solve the problems of a large amount of calculation, low efficiency and limited to qualitative research existing in the traditional phase-field models. [ABSTRACT FROM AUTHOR]

To achieve high‐precision position control for the active magnetic bearing high‐speed flywheel rotor system (AMB‐HFRS), a novel control strategy based on inverse system method and extended two‐degree‐of‐freedom (2‐DOF) proportional–integral–derivative (PID) controller is proposed in this study. First, the inverse system method is employed to decouple the AMB flywheel rotor system with strong non‐linear and coupling, into four independent subsystems. Subsequently, extended 2‐DOF PID controllers are used to regulate the decoupled subsystems, to obtain good performances of disturbance rejection and tracking simultaneously. In the extended 2‐DOF PID controller, a differential signal is produced by a velocity observer to improve the ability of against noise. Finally, the characteristics of stability, tracking, disturbance rejection and robustness of the control strategy proposed are analysed in theory, and its ability and effectiveness to control the radial position of the AMB‐HFRS are further studied by simulations and experiments. It is shown that the control strategy proposed can keep the AMB‐HFRS suspending stably from static state to the speed of 24,000 rpm, has the advantages of good tracking, high disturbance rejection, strong robustness and good ability of against noise. [ABSTRACT FROM AUTHOR]

Soft sensors have been extensively utilized to approximate real-time power prediction in wind power generation, which is challenging to measure instantaneously. The short-term forecast of wind power aims at providing a reference for the dispatch of the intraday power grid. This study proposes a soft sensor model based on the Long Short-Term Memory (LSTM) network by combining data preprocessing with Variational Modal Decomposition (VMD) to improve wind power prediction accuracy. It does so by adopting the isolation forest algorithm for anomaly detection of the original wind power series and processing the missing data by multiple imputation. Based on the process data samples, VMD technology is used to achieve power data decomposition and noise reduction. The LSTM network is introduced to predict each modal component separately, and further sum reconstructs the prediction results of each component to complete the wind power prediction. From the experimental results, it can be seen that the LSTM network which uses an Adam optimizing algorithm has better convergence accuracy. The VMD method exhibited superior decomposition outcomes due to its inherent Wiener filter capabilities, which effectively mitigate noise and forestall modal aliasing. The Mean Absolute Percentage Error (MAPE) was reduced by 9.3508%, which indicates that the LSTM network combined with the VMD method has better prediction accuracy. [ABSTRACT FROM AUTHOR]

This paper presents a multi-objective optimized design for a 75 kW, 24 000 r/min high-speed surface-mounted permanent magnet synchronous motor (SMPSM) for a magnetically levitated flywheel energy storage system. The main goal of the optimization process is to determine the optimal motor geometry, and thus obtain maximum efficiency, minimum weight, and minimum torque ripple in the SMPSM. To achieve this goal, three objective functions are used. The first function is used to obtain maximal output torque, and thus produce highest efficiency; the second function is used to minimize materials utilization to realize the lowest possible production cost; and the third function is used to achieve minimal torque ripple, and thus constrain the motor’s vibration and noise. The optimization process uses an ant colony algorithm with continuous domains. The optimized motor parameters can be selected from the Pareto solution set obtained. A comparison of the results calculated using the optimization algorithm with the results obtained using finite-element analysis software shows a good agreement. [ABSTRACT FROM AUTHOR]

Based on the AFEPack adaptive software package, the H-adaptive finite element method was used to solve the three-dimensional phase field model on the Linux platform. The growth of the three-dimensional dendrites in the undercooling melt was simulated numerically, and the effects of different undercooling on three-dimensional dendritic growth were studied. The real growth process of three-dimensional dendritic was reproduced. The dendritic growth pattern that we obtained was consistent with the crystallization theory. In order to verify the reliability of the simulation results, the three-dimensional dendrite tip growth rate and the tip radius were compared with the classical theory and the same conditions under the literature value. The results are compared with those obtained by Jeong et al. and obtained by finite difference method under the same conditions. It is found that the results obtained by H-adaptive finite element method are in agreement with the calculated results obtained by these two methods. It is proved that the H-adaptive finite element method is feasible to simulate the growth of three-dimensional dendrites. The method greatly reduces the computational cost of the phase field model solution and improves the efficiency of the solution. [ABSTRACT FROM AUTHOR]

Background and Aim: Recently alcohol septal ablation (ASA) has emerged as an alternative treatment for drug-refractory hypertrophic obstructive cardiomyopathy (HOCM) and a subgroup of HOCM patients with previous ASA may need myectomy. However, subsequent outcome and mechanism of residual obstruction has not been determined. This study aims to determine outcome after myectomy and mechanism of residual obstruction in HOCM patients with previous ASA.Methods: From February 2009 to June 2017, 38 HOCM patients with previous ASA underwent surgical septal myectomy at our institution. Seventy-six patients who underwent surgical septal myectomy initially were included as the comparison group through one-to-two propensity score matching method.Results: Fourteen available cardiac magnetic resonance images revealed inferior location and small area of infarcted myocardium induced by ASA in 12 patients and outside targeted location in two patients. During follow-up (median, 2.4; maximum, 7.8 years), event-free survival at 7 years was 83.2% in the previous ASA group and 94.6% in the comparison group, respectively (P = 0.0378). Multivariable analysis indicated previous ASA (hazard ratio, 4.28; 95% confidence intervals [CI], 1.20-15.26; P = 0.025) and postoperative left ventricular end-diastolic diameter (hazard ratio, 1.14; 95% CI, 1.05-1.23; P = 0.002) were independent predictors of adverse events.Conclusions: This study demonstrated that uncontrollable extent and location of infarcted myocardium induced by ASA may attribute to residual obstruction after previous ASA, and the long-term event-free survival after myectomy was inferior. It may provide special precaution to patient selection and the increased number of ASA practiced worldwide. [ABSTRACT FROM AUTHOR]

To eliminate the influence of gyroscopic effect on system stability and to improve the control performances for the active magnetic bearing (AMB) high‐speed flywheel rotor system, a novel control strategy based on the modal separation and inverse system method is proposed. The translational motions and rotational motions of the AMB flywheel rotor system are firstly decoupled by the modal separation, then the rotational motions are decoupled by the inverse system method, so that the AMB flywheel rotor system, which is a multivariable and strong coupled system, is decoupled into four subsystems. Finally, the subsystems are regulated by four two‐degrees‐of‐freedom (2‐DOF) internal model controllers, respectively. Furthermore, the stability, tracking and robustness of the novel control strategy are analysed theoretically, and its effectiveness on vibration control of the AMB high‐speed flywheel rotor system is further investigated by simulations and experiments. The results show that the novel control strategy can achieve stable suspension and effectively suppress the vibration of the AMB high‐speed flywheel rotor system from static state to 24,000 rpm, with the advantages of high stability, strong robustness, and good performances of tracking and disturbance rejection simultaneously. [ABSTRACT FROM AUTHOR]

The self-sensing active magnetic bearing (SAMB) rotor systems own the benefits of reduced cost and better system integration, from the substitution of rotor displacement estimation for external sensors. However, the self-sensing errors between the real and estimated rotor displacement, together with the unbalance force and sensor runout, will act as disturbances that affect the SAMB rotor system, inducing current fluctuations and rotor vibrations. This paper presents a disturbance suppression method for the modulation-type SAMB rotor systems, in which both the amplitude and phase of disturbances are identified and real-time updated. A lumped multifrequency disturbances model is established. And a disturbances identification algorithm with object function value-based step vectors is proposed. The system stability and method convergence conditions are analyzed. The convergence rate, overshoot and antinoise capacity of the method are verified through simulations. In the end, the effectiveness and performance of the suppression method are validated through steady state and varying rotational speed experiments on a 4-DOF radial SAMB rigid rotor platform. [ABSTRACT FROM PUBLISHER]

A microstructure numerical model is an intensive computational problem, for which the simulation time is too long and the simulation scale is too small. To solve these two problems, in this article, we use MPI+CUDA hybrid particle heterogeneous parallel computing to implement the dendrite growth simulation of a PF-LBM phase-field 3D model. Message Passing Interface (MPI) can be used to conduct coarse granularity division, to break through the limitation of the simulate scale in a single machine. In each node, fine-grained division is implemented by the Compute Unified Device Architecture (CUDA) parallel way to realize the completely parallelism intra-node, and to improve overall computational efficiency. At the same time, in this article, the "pseudo three-dimensional array" programming method is brought up in CUDA programming, and also to improve the CUDA random number generation method, in order to simplify the CUDA array programming and reduce the CUDA random number generation time purposes. Experiments show that at the same simulation scale, the speed-up ratio with 21 nodes MPI+CUDA was 57, which was increased 54% over the 21 nodes MPI. Under the condition of computing efficiency close, the largest simulation scale with 21 nodes MPI+CUDA was 4203, which is 13 times to single GPU. Therefore, the MPI + CUDA hybrid granularity parallel method proposed in this paper also has the advantages of high computational efficiency of the GPU and MPI to expand the simulation scale. [ABSTRACT FROM AUTHOR]

By coupling the phase field model of dendrite growth with the Lattice Boltzmann method (LBM), a Phase field LBM model (PF-LBM) that can simulate 3D dendrite non-isothermal growing from the under-cooled melt of a pure substance in forced flow has been established. Taking high-purity succinonitrile (SCN) as an example, the effects of flow on 3D dendritic growth were studied. The calculation efficiency of LBM and SOLA algorithm was compared under the same condition. The results show that, with the PF-LBM model, the effects of forced flow on 3D dendrite growth morphology and the dendrite asymmetric growth can be quantitatively modeled in large scale, and the dendrite growth is consistent with the crystallization theory. The LBM algorithm overcomes the weakness of a large amount of calculation and slow computation speed that exists in the traditional algorithm, and it achieves a speedup of 11.7 when the calculation region size is 200. [ABSTRACT FROM AUTHOR]

To represent the support characteristic of active magnetic bearings (AMB), the commonly used parameters are the equivalent stiffness and the equivalent damping, which inherit the parameters of the stiffness and the damping from traditional mechanical bearings. First, by analyzing the diversity and the similarity between traditional mechanical bearing and AMB, the prior condition for applying the parametric representation of equivalent stiffness and equivalent damping to AMB is illuminated. Then, a method for measuring the equivalent stiffness and the equivalent damping of AMB-rotor system is proposed with multi-frequency excitation. One of its outstanding features is that the proposed method is based on the multi-degree of freedom (DOF) rotor model, not the single- DOF model, because the single DOF model cannot be suitably applied to the multi-DOF AMB-rotor systems. Otherwise, in order to decrease the identification error, the multi-frequency excitation can achieve the lowest peak value by means of appropriate selection for the relative phasing of each component, so that the possibility of the rotor displacement exceeding clearances of AMB and the magnetic force reaching saturation is minimized. Finally, the experiments, which are carried out on an AMB-rotor test rig with a vertical shaft, indicate that the proposed method can efficiently reduce the peak value for the superimposed multi-frequency excitation and correctly identify the equivalent stiffness and equivalent damping of AMB-rotor system. [ABSTRACT FROM AUTHOR]

An active unbalanced vibration compensation scheme with built-in force actuator for a flexible switched reluctance motorized spindle (SRMS) is proposed. The force actuator is a set of windings, which are wound on the stator pole of the switched reluctance motor (SRM). The equivalent unbalance identification method is proposed to indentify online the unbalanced vibration caused by the grinding wheel’s mass imbalance. The equivalent reference unbalance compensation signal is produced by the identification method, which is used to obtain the compensation current of a force actuator, so a controlled, non-contact electromagnetic compensation force on the rotor of the SRMS is produced by the force actuator to compensate the actively unbalanced vibration of the flexible SRMS. The dynamic flexible SRMS is modeled by means of finite element method (FEM). The inductance of main and control windings, the coefficients of the compensation and the unbalanced magnetic pull force are identified by the FEM, and then the active unbalanced vibration compensation scheme for the flexible SRMS is designed in Matlab, in which inductance of main and control windings, the coefficients of the compensation and unbalanced magnetic pull force are obtained by the Look-up table method. The results show that the proposed active unbalanced force compensation scheme has an obvious compensation effect and the coefficients indentified by the FEM have been closer to an actual effect on compensating the unbalanced vibration of the flexible SRMS. [ABSTRACT FROM PUBLISHER]

Highlights: [•] We simulated three-dimensional dendritic growth process quantitatively. [•] We explored a high performance computing method based on CUDA+GPU. [•] We implemented large-scale computing to improve computational efficiency. [•] We compared the computational efficiency between GPU and CPU. [•] We proved the validity of GPU parallel algorithm. [Copyright &y& Elsevier]

An active vibration control scheme is proposed for suppressing the vibration of the high-speed induction electric spindle with a built-in force actuator to improve the performance of high-speed milling system. The built-in force actuator is a set of windings, which are added to the stator of electric spindle motor. An improved fast block least mean square (FBLMS) adaptive filter is adopted to produce the reference control force, which is used to obtain the control current of force actuator, and then a controlled, non-contact electromagnetic control force on the electric spindle is produced by the force actuator to control actively chatter, unbalanced vibration and disturbance signals of milling system. The built-in motorized spindles dynamic is modeled by means of the finite element method, the dynamic milling, the air gap excitation current of torque and radial electromagnetic control force are modeled, the control force coefficient and the unbalanced magnetic pull force coefficient are identified by finite element analysis, and then the active vibration control scheme for the flexible induction electric spindle is designed. The vibration, with a different frequency component, is investigated. The results show that the improved FBLMS adaptive filter and the proposed active control scheme have an obvious effect on suppressing the spindle chatter, unbalanced vibration and other frequency vibration components in the built-in motorized milling spindle. [ABSTRACT FROM AUTHOR]

Atrial high-rate episode (AHRE) and stroke are related; however, the magnitude of the correlations between different AHRE burdens and stroke remains unknown. We analysed studies that evaluated this relationship. We searched for observational controlled studies that reported the associations of different AHRE burdens with stroke in populations with cardiac implantable electronic devices (CIEDs). The primary endpoint was stroke or thrombosis during follow-up. We performed subgroup analyses according to the classification criteria and research design of the included studies. Of the 5985 studies identified, 9 met the eligibility criteria and included 42,958 patients. Patients with low and high AHRE burdens had a 1.2-fold risk of stroke (no heterogeneity) and a 2.52-fold risk of stroke (moderate heterogeneity), respectively. After excluding studies analysing the atrial fibrillation history, no significant difference in progressive stroke risk was observed for patients with a low AHRE burden (without significant heterogeneity). An increased likelihood of stroke was observed for patients with a high AHRE burden (decreased heterogeneity). Four of the nine studies classified high and low AHRE burdens using the longest AHRE time. Five studies classified high and low AHRE burdens based on the median of the total AHRE time as the cutoff value. Low and high AHRE burdens were more closely related to stroke when classified by the total AHRE duration than when classified by the single longest AHRE duration. For populations with CIEDs without an atrial fibrillation history, a high AHRE burden was significantly associated with stroke. Compared with patients without AHRE, those with low and high AHRE burden had a 1.2- and 2.52-fold risk of stroke, respectively. (A) After excluding studies analysing the atrial fibrillation history, no significant difference was observed in the progressive stroke risk among patients with a low AHRE burden; an increased risk of stroke was noted for patients with a high AHRE burden. (B) Four of the nine studies classified the high and low AHRE burdens using the longest AHRE time. (C) Five studies classified the high and low AHRE burdens based on the median of the total AHRE time as the cutoff value (D). Low and high AHRE burdens were related to stroke more closely when classified by the total AHRE duration than when classified by the single longest AHRE duration (C and D). [Display omitted] • The magnitude of the correlation between different levels of AHRE burden and stroke remains unknown. • A high AHRE burden in the CIED population was closely associated with the risk of stroke(2.5-fold), and the association was increased (3.89-fold) after excluding studies that included patients with a history of AF. • Compared with the classification according to the longest AHRE time within a certain period, both high and low AHRE burdens of patients with CIEDs had higher associations with predicting stroke when classified by the total AHRE time within a certain period. • The high AHRE burden of patients with CIEDs was clearly associated with a higher risk of clinical AF. [ABSTRACT FROM AUTHOR]

An analytical subdomain model for the prediction of open-circuit magnetic field in slotted surface-mounted permanent-magnet machines is developed in this paper, which considers the effect of rotor eccentricity. The magnetic field domain is divided into three types of simple and regular subdomains, viz. magnet, air gap, and stator slots. The analytical solution is derived by solving the field governing equations in each subdomain and applying the boundary conditions to the interfaces between these subdomains. The perturbation method is used to describe the effect of rotor eccentricity. The model accurately accounts for the effect of stator slots, the mutual influence between slots, and rotor eccentricity. The analytical model is validated by the corresponding finite-element results. The results show that the proposed subdomain model up to the first-order perturbation can accurately predict the open-circuit magnetic field in slotted surface-mounted permanent-magnet machines with rotor eccentricity. [ABSTRACT FROM AUTHOR]

The undesired synchronous vibration due to rotor mass imbalance is a main disturbance source in all rotating machinery including active magnetic bearing (AMB)-rotor systems. In the AMB-rotor system, imbalance compensation, which causes the AMB actuators to spin a rotor about its geometric axis, and automation balancing, which spins a rotor about its inertial axis, are two kinds of common control aim for the rotor imbalance control. In this study, the internal relation between the imbalance compensation and the automation balancing is analyzed and a uniform control method is proposed. With the identical control algorithm, the proposed control method can realize the automation balancing or the imbalance compensation, respectively, by switching the controller's junction position in the original control loop. The proposed control method does not depend on the dynamic plant model, because its algorithm is based on the real-time identification for the Fourier coefficient of the rotor imbalance disturbance. In this paper, the process of identification algorithm is given in detail and all the possible junction forms of the controller are illustrated. By the simulations, the identification performances of the control algorithm are compared in the conditions with three variable factors, including the signal noise ratio (SNR), the imbalance phase and the identification delay time. The noise level has considerable influence on the identification precision, but the imbalance phase has little. To prolong the identification delay time will be of benefit to improve the identification precision but slow down the identification process. Experiments, which are carried out on an AMB-rigid rotor test rig, indicate that by switching the junction position of the controller in control loop, both kinds of rotor imbalance control can achieve the good effectiveness. [ABSTRACT FROM AUTHOR]

Abstract: A method for multi-frequency periodic vibration suppressing in active magnetic bearing (AMB)-rotor systems is proposed, which is based on an adaptive finite-duration impulse response (FIR) filter in time domain. Firstly, the theoretic feasibility of the method is proved. However, two problems would be unavoidable, if the conventional adaptive FIR filter is adopted in practical application. One is that the convergence rate of the different frequency components may be highly disparate in multi-frequency vibration control. The other is that the computational complexity is significantly increased because the long memory FIR filter is required to match the transient response time of the AMB-rotor system. To overcome the problems above, the Fast Block Least Mean Square (FBLMS) algorithm is adopted to efficiently implement the computation in frequency domain at a computational cost far less than that of the conventional FIR filter. By the FBLMS algorithm, regardless of the number of the considered frequency components in vibration disturbance, the computational complexity would be invariable. Moreover, filter’s weights in the FBLMS algorithm have the intuitional relation with signal’s frequency. As a result, the convergence rate of each frequency component can be adjusted by assigning the individual step size parameter for each weight. Experiments with the reciprocating simulating disturbance test and the rotating harmonic vibration test were carried out on an AMB-rigid rotor test rig with a vertical shaft. The experiment results indicate that the proposed method with the FBLMS algorithm can achieve the good effectiveness for suppressing the multi-frequency vibration. The convergence property of each frequency component can be adjusted conveniently. Each harmonic component of the vibration can be addressed, respectively, by reconfiguring the frequency components of the reference input signal. [Copyright &y& Elsevier]

Abstract: For a flexible rotor system under seismic excitation, H 2, H ∞ and mixed H 2/H ∞ control strategies were formulated by means of linear matrix inequality (LMI) to attenuate the transient vibration of the flexible rotor system under a nonstationary seismic excitation and to improve robust performance of the flexible rotor system. A double-disc cantilever flexible rotor system was used as an example to verify the feasibility and the validity of the H 2, H ∞ and mixed H 2/H ∞ control strategies in active vibration control for a rotor system subjected to nonstationary El Centro seismic excitation. The performances of the rotor system in both frequency and time domains were analysed based on numerical optimization technique, which bases on an efficient convex optimization software. The feasibility and the effectiveness of the control strategies presented in active vibration control for a rotor system were verified. It is shown that for the H ∞ control, the displacement responses of the rotor system are effectively suppressed in the frequency domain, but transient-response performances are not so good. For the H 2 control, the transient responses of the rotor system attenuate quickly, but the frequency-response performances are not so good. The effectiveness of the mixed H 2/H ∞ control to suppress the displacement responses of the rotor system in the frequency domain and the transient response in time domain greatly depends on the H ∞ performance index. If the H ∞ performance index in the mixed H 2/H ∞ control is properly chosen, the mixed H 2/H ∞ control can effectively suppress both the displacement responses of the rotor system in the frequency domain and the transient response in time domain. [Copyright &y& Elsevier]

Abstract: Based on the particular characteristic of a magneto-rheological (MR) fluid, i.e., a rapid, reversible and dramatic change in its rheological properties produced by the application of an external magnetic field, a simple disk-type MR fluid damper operating in shear flow mode is presented in this paper. The magnetic field of the disk-type MR fluid damper is analyzed by the finite element method in order to show if the design is reasonable. The effect of excitation current in the coil on the magnetic flux density in the axial gaps filled with the MR fluid is studied both theoretically and experimentally. Finally, the effectiveness of the disk-type MR fluid damper for attenuating the vibration of rotor systems and of a simple open-loop on-off control based on the feedback of rotational speed for controlling vibration of rotor systems are experimentally studied in a flexible rotor system. It is shown that the dynamic characteristics of the disk-type MR fluid damper can be easily controlled by a steady magnetic field produced by a simple electrical magnetic coil with a low DC current (less than 1A) and that the disk-type MR fluid damper is very effective for attenuating and controlling the vibration of the rotor systems. It is possible to supply the optimum supporting damping for every vibration mode in the rotor system by using the disk-type MR damper, if the location of the disk-type MR fluid damper in the rotor is properly chosen. [Copyright &y& Elsevier]

The dynamic characteristics of a cracked rotor with an active magnetic bearing (AMB) are theoretically analyzed in this paper. The effects of using optimal controller parameters on the dynamic characteristics of the cracked rotor and the effect of a crack on the stability of the active control system are discussed. It is shown that the dynamic characteristics of the cracked rotor with AMBs are clearly more complex than that of the traditional cracked rotor system. Adaptive control with AMBs may hide the fault characteristics of the cracked rotor, rather than helping to diagnose a crack; this will depend on the controller strategy used. It is very difficult to detect a crack in the rotor with an AMB support system when the vibration of the rotor system is fully controlled. Monitoring the super-harmonic components of 2× and 3× revolution in the sub-critical speed region can be used as an index to detect a crack in the rotor with an AMB system. If the effect of the crack is not taken into account at the design stage of the controller, then the rotor–AMB system will lose its stability in some cases when cracks appear. [Copyright &y& Elsevier]

Local planning is a critical and difficult task for intelligent vehicles in dynamic transportation environments. In this paper, a new method Suppress Q Deep Q Network (SQDQN) combining traditional deep reinforcement learning Deep Q Network (DQN) with information entropy is proposed for local planning in automatic driving. In the proposed approach, local planning strategy in complex traffic environment established by the actor–critic network based on DQN, the method adopts the way of execution action-evaluation action-update network to explore the optimal local planning strategy. Proposed strategy does not rely on accurate modeling of the scene, so it is suitable for complex and changeable traffic scenes. At the same time, evaluate the update process and determine the update range by using information entropy to solve a common problem in the network that over expectation of actions damage the performance of strategies. Use this approach to improve strategic performance. The trained local planning strategy is evaluated in three simulation scenarios: overtaking, following, driving in hazardous situations. The results illustrate the advantages of the proposed SQDQN method in solving local planning problem. [ABSTRACT FROM AUTHOR]

Fringe projection profilometry (FPP), with benefits such as high precision and a large depth of field, is a popular 3D optical measurement method widely used in precision reconstruction scenarios. However, the pixel brightness at reflective edges does not satisfy the conditions of the ideal pixel-wise phase-shifting model due to the influence of scene texture and system defocus, resulting in severe phase errors. To address this problem, we theoretically analyze the non-pixel-wise phase propagation model for texture edges and propose a reprojection strategy based on scene texture modulation. The strategy first obtains the reprojection weight mask by projecting typical FPP patterns and calculating the scene texture reflection ratio, then reprojects stripe patterns modulated by the weight mask to eliminate texture edge effects, and finally fuses coarse and refined phase maps to generate an accurate phase map. We validated the proposed method on various texture scenes, including a smooth plane, depth surface, and curved surface. Experimental results show that the root mean square error (RMSE) of the phase at the texture edge decreased by 53.32%, proving the effectiveness of the reprojection strategy in eliminating depth errors at texture edges. [ABSTRACT FROM AUTHOR]

Open in new tab Download slide OBJECTIVES This study aimed to assess the effectiveness of three-dimensional printing (3DP) in patients with complex hypertrophic cardiomyopathy requiring combined transaortic and transapical septal myectomy. METHODS We created 3DP models for 7 patients undergoing this surgery approach between June and October 2022 using silicone-like resin and conducted mock operations. The models were compared with echocardiography to identify abnormal muscle bundles and heart structures. These patients were then compared with a 1:2 matched group without 3DP, considering age, sex and additional operations. RESULTS The models mostly presenting with midventricular obstruction showed high consistency with original computed tomography data (r  = 0.978, P  <   0.001). 3DP identified more abnormal muscle bundles than echocardiography, primarily between the interventricular septum and apex. Excised specimens in mock operations mirrored those in actual myectomies. While cardiopulmonary bypass time was not significantly different, a near-20-min decrease was observed in the 3DP group (135.5 ± 31.1 vs 154.4 ± 36.6 min, P  =   0.054). CONCLUSIONS While no significant differences in surgical outcomes were observed, 3DP appeared to enhance the visualization and understanding of spatial structures (average Likert scale score 4.0), potentially contributing to surgical proficiency (overall rating score 3.9). The use of 3DP may offer additional value in the preparation and execution of operations for complex hypertrophic cardiomyopathy cases. [ABSTRACT FROM AUTHOR]

In the process of dendritic growth simulation, the computational efficiency and the problem scales have extremely important influence on simulation efficiency of three-dimensional phase-field model. Thus, seeking for high performance calculation method to improve the computational efficiency and to expand the problem scales has a great significance to the research of microstructure of the material. A high performance calculation method based on MPI+CUDA hybrid programming model is introduced. Multi-GPU is used to implement quantitative numerical simulations of three-dimensional phase-field model in binary alloy under the condition of multi-physical processes coupling. The acceleration effect of different GPU nodes on different calculation scales is explored. On the foundation of multi-GPU calculation model that has been introduced, two optimization schemes, Non-blocking communication optimization and overlap of MPI and GPU computing optimization, are proposed. The results of two optimization schemes and basic multi-GPU model are compared. The calculation results show that the use of multi-GPU calculation model can improve the computational efficiency of three-dimensional phase-field obviously, which is 13 times to single GPU, and the problem scales have been expanded to 8193. The feasibility of two optimization schemes is shown, and the overlap of MPI and GPU computing optimization has better performance, which is 1.7 times to basic multi-GPU model, when 21 GPUs are used. [ABSTRACT FROM AUTHOR]

Nowadays, high-frequency switching power amplifiers (SPA) have been studied widely; bulk of the researches were focused on audio power amplifiers. In active magnetic bearing (AMB) systems, high-frequency electromagnetic excitation caused by rotor imbalance can affect the performance of the SPA, so the traditional SPA cannot meet the requirements of the AMB systems. Therefore, on the premise of ensuring larger power, the frequency of the SPA should be improved to ensure the normal operation of the AMB system. Two-level pulsewidth modulation (PWM) current-mode SPAs are widely used in AMB systems. In order to broaden the bandwidth and to reduce the average steady-state error current, SiC power devices based SPA with a high bus voltage and a high switching frequency was designed. The basic principle and the linearized control model of SPAs are introduced. Then, the duty ratio stability and average steady-state error current of the SPAs are analyzed based on the output ripple current. When the PWM modulator is designed by either the discrete devices or the integrated chips, the critical gains to ensure the duty ratio stability are, respectively, analyzed based on the slope matching and the nonideal characteristic of operational amplifiers. Hence, two methods to reduce the average steady-state error current are proposed, respectively. One is to adjust the offset voltage of triangular carrier for the P controller, the other is to use a proportional integral (PI) controller. The offset adjusting method allows the SPA to achieve better dynamic performance and wider bandwidth. The proportional integral (PI) controller can reduce the average steady-state error current but narrows the bandwidth. Finally, the experiment results are in good agreement with the theoretical analyses. [ABSTRACT FROM AUTHOR]

Mitral annular calcification (MAC) is a risk factor for cardiac surgery, but there is limited study on the prognosis value and the impact for valve function of MAC based on computed tomography (CT) diagnosis after myectomy for hypertrophic obstructive cardiomyopathy (OHCM). Consecutive OHCM patients underwent septal myectomy were compared according to the existence of MAC and its severity in preoperative CT scans. The survival data were evaluated and compared by Kaplan Meier analysis and log rank test. Cox regression analysis was used to evaluate the impact of MAC on endpoint events. From the entire cohort of 1035 patients, 10.8% had MAC. In multivariate regression, female (OR = 2.23), age (OR = 1.07), aortic annular calcification (OR = 2.52), aortic calcification (OR = 2.56), systolic anterior motion of the mitral valve (SAM) (OR = 0.42), mitral valve thickening (OR = 2.13), and tricuspid regurgitation (OR = 3.12) were independent predictors of MAC. All-cause mortality (3.57% vs. 1.08%, p = 0.031), major adverse cardiovascular and cerebrovascular events (MACCE) (23.32% vs. 13.65%, p = 0.014), recurrent MR > 2+ (8.04% vs. 2.49%, p = 0.001) and NYHA III-IV (11.61% vs. 5.53%, p = 0.012) were more frequent in OHCM patients with MAC after myectomy. MAC was discovered to be an independent predictor of postoperative recurrent MR > 2+ after other risk factors were taken into account (HR 2.47, 95% CI 1.08–5.67, p = 0.0329). Moderate-to-severe MAC was an independent risk factor (HR 2.03, 95% CI 1.09–3.75, p = 0.0244) for long-term major adverse cardiovascular and cerebrovascular events (MACCE). MAC was detected in one-tenth of OHCM patients in preoperative CT scanning and is mainly associated with aging and atherosclerosis. OHCM patients with MAC had a worse prognosis and more recurrent mitral valve regurgitation than those without MAC after septal myectomy. • The incidence of mitral annulus calcification in patients who had septal myectomy for hypertrophic obstructive cardiomyopathy was 10.8% in this large-scale CT diagnostic research. • There were the following baseline predictors of mitral annulus calcification: female, older age, aortic annular calcification, aortic calcification, systolic anterior motion of the mitral valve, mitral valve thickening, and preoperative tricuspid regurgitation. • In long-term follow-up, patients with mitral annulus calcification have a worse prognosis. Moderate-to-severe MAC was the risk factor for MACCE, and MAC was the risk factor of recurrent mitral regurgitation. • To reduce the risk posed by operating on calcified annulus, we used multiple surgical techniques. [ABSTRACT FROM AUTHOR]

Background: The mid-term outcome of patients with hypertrophic obstructive cardiomyopathy (HOCM) undergoing coronary artery bypass graft (CABG) is unclear.Materials and Methods: We studied 44 patients with HOCM and coronary artery disease (CAD) who underwent septal myectomy and CABG) between 2011 and 2017. The control group was matched in a ratio of 4:1 based on age, sex, body mass index, hypertension, and chest pain.Results: Compared to patients without CAD, patients with CAD had a higher long-term cardiovascular mortality rate (0.6% vs 6.8%, P = 0.03; hazard ratio [HR] = 8.16, 95% confidence interval [CI]: 1.27-74.48, P = 0.03). In addition, 10 out of 176 (5.7%) patients without CAD and nine out of 44 (20.5%) patients with CAD achieved the secondary endpoints (progressive heart failure, unexplained syncope, stroke, atrial fibrillation, and myocardial infarction) (HR = 2.89, 95%CI: 1.03-8.12, P = 0.04). The 5-year survival rate and cardiovascular event-free survival rate were significantly higher in patients without CAD than in those with CAD (97.4% vs 93.9%, P = 0.03; 89.2% vs 80.1%; P = 0.04). In the multivariate analysis, presence of CAD, New York Heart Association class, and left atrial diameter were predictors of combined cardiovascular events when adjusted for age and male sex.Conclusions: The cardiovascular death and cardiovascular events are significantly increased in patients with HOCM and CAD who underwent CABG at the time of septal myectomy. [ABSTRACT FROM AUTHOR]

This study uses deep reinforcement learning (DRL) combined with computer vision technology to investigate vehicle fuel economy. In a driving cycle with car-following and traffic light scenarios, the vehicle fuel-saving control strategy based on DRL can realize the cooperative control of the engine and continuously variable transmission. The visual processing method of the convolutional neural network is used to extract available visual information from an on-board camera, and other types of information are obtained through the vehicle's inherent sensor. The various detected types of information are further used as the state of DRL, and the fuel-saving control strategy is built. A Carla–Simulink co-simulation model is established to evaluate the proposed strategy. An urban road driving cycle and highway road driving cycle model with visual information is built in Carla, and the vehicle power system is constructed in Simulink. Results show that the fuel-saving control strategy based on DRL and computer vision achieves improved fuel economy. In addition, in the Carla–Simulink co-simulation model, the fuel-saving control strategy based on DRL and computer vision consumes an average time of 17.55 ms to output control actions, indicating its potential for use in real-time applications. [ABSTRACT FROM AUTHOR]

Identification and composite control of Hammerstein system with unknown order linear dynamics and a static hysteresis non‐linearity modelled by Preisach operator is investigated. The order of linear dynamics is firstly determined by Hankel matrix approach and then a blind identification is implemented to identify the linear dynamics based on the over‐sampling output measurements only. Then a novel deterministic approach is proposed to identify the Preisach model for hysteresis non‐linearity, which is devoted to identify a triangle matrix. This novel approach needs less dimensions to obtain Preisach density function than other existing methods. Finally, a composite control consisting of discrete inverse model‐based controller (DIMBC) and discrete adaptive sliding mode controller (DASMC) is developed to achieve tracking control. The composite control can reduce the reaching time of DASMC and improve the robustness of DIMBC. Experiments based on a turntable servo system demonstrate the effectiveness of the proposed identification and control methods. [ABSTRACT FROM AUTHOR]

Background: Myocardial bridging (MB) is commonly treated in patients with hypertrophic cardiomyopathy. However, whether and how MB should be treated in patients with hypertrophic obstructive cardiomyopathy (HOCM) who underwent septal myectomy remain unclear. Methods: A total of 823 adults with HOCM who underwent septal myectomy at the Fuwai Hospital from 2011 to 2017 were retrospectively studied. Results: Overall, 31 events occurred: 24 patients died and 7 had nonfatal myocardial infarction (MI). The 3‐year cumulative event‐free survival of all‐cause death (97.9% vs. 100% vs. 100% vs. 98.4%, p =.89) and cardiovascular death (98.3% vs. 100% vs. 100% vs. 98.4%, p =.63) were similar among the four groups (non‐MB, coronary artery bypass grafting [CABG], unroofing, untreated, respectively). However, the 3‐year cumulative event‐free survival of nonfatal MI (100% vs. 97.5% vs. 98.0% vs. 89.9%, p <.001) and combined endpoints (97.9% vs. 97.5% vs. 98.0% vs. 88.4%, p =.02) were significantly lowest in untreated MB (non‐MB, CABG, unroofing, untreated, respectively). Cox regression analysis indicated that untreated MB was a significant independent predictor of combined endpoints (hazard ratio: 4.06, 95% confidence interval: 1.60–10.32, p <.001). Moreover, 49 patients underwent coronary artery computed tomography 1 year after surgery. The patency rate of the saphenous vein graft was significantly higher than that of the left internal mammary artery (13.3% vs. 84.2%, p <.001). No MB was detected in the unroofing group. Conclusions: Surgical MB treatment could be beneficial and performed safely during septal myectomy. Myocardial unroofing is the recommended treatment for MB, and unroofing when technically possible may be preferable for long‐term outcomes. [ABSTRACT FROM AUTHOR]

Background: The prevalence of obstructive sleep apnoea (OSA) is high in patients with hypertrophic cardiomyopathy. The effect of septal myectomy on OSA is not clear. This study aimed to examine the association between hypertrophic obstructive cardiomyopathy and OSA before and after septal myectomy.Method: We included 85 consecutive patents with a confirmed diagnosis of hypertrophic obstructive cardiomyopathy who underwent septal myectomy. Polysomnography was performed in all patients before and 3 months after the surgery.Results: Of the 85 patients, 49 (58%) were diagnosed with OSA. Patients with OSA were significantly older than those without OSA. The incidence of atrial fibrillation significantly increased during the perioperative period in patients with OSA (p = 0.03). The severity of OSA significantly increased 3 months after surgery, as determined by the apnoea-hypopnoea index (AHI; p < 0.001), obstructive apnoea index (p = 0.024), and hypopnoea index (p = 0.003), whereas central apnoea index was decreased (p = 0.008). In the multivariate linear regression analysis, mean oxygen desaturation and time% with SpO2 <90% during sleep before surgery were significantly associated with increased AHI, independently of body mass index and sex (p = 0.026 and p = 0.007, respectively; adjusted R2 = 0.365).Conclusions: The severity of OSA significantly increased 3 months after septal myectomy as determined by AHI, obstructive apnoea index, and hypopnoea index. Mean oxygen saturation and time% with SpO2 <90% during sleep before surgery were independently associated with the increase of AHI. However, the specific mechanism of such deterioration of OSA after septal myectomy needs to be determined in detail. [ABSTRACT FROM AUTHOR]

Background: Animal studies suggested that blocking the activation of the mammalian target of rapamycin (mTOR) pathway might be effective to treat cardiac hypertrophy in LEOPARD syndrome (LS) caused by PTPN11 mutations.Results: In the present study, mTOR pathway activity was examined in human myocardial samples from two patients with LS, four patients with hypertrophic cardiomyopathy (HCM), and four normal controls. The two patients with LS had p.Y279C and p.T468 M mutations of the PTPN11 gene, respectively. Although PTPN11 mutation showed initially positive regulation on phosphoinositide 3-kinase, overall the mTOR complex 1 pathway showed widely attenuated activity in LS. This included mildly hypophosphorylated mTOR and ribosomal protein S6 kinase and significantly hypophosphorylated Akt308 and ribosomal protein S6, which is similar to HCM. Akt473 is a basal molecule of the mTOR complex 2 pathway. Akt473 was less affected and showed hyperactivity in LS compared with HCM and normal controls. Additionally, MAPK/ERK kinase and ERK1/2 were significantly more phosphorylated in both HCM and LS than normal controls.Conclusions: In LS, the mTOR signaling pathway shows similar activity to HCM and is attenuated compared with normal controls. Thus, caution should be applied when using rapamycin to treat heart hypertrophy in LS. [ABSTRACT FROM AUTHOR]

Background: Type 2 diabetes mellitus is common in cardiovascular disease. It is associated with adverse clinical outcomes for patients who had undergone coronary artery bypass and valve operations. The aim of this study was to evaluate the impact of type 2 diabetes mellitus on the midterm outcomes of patients with hypertrophic cardiomyopathy who underwent septal myectomy. Methods: We retrospectively analyzed the data of 67 hypertrophic cardiomyopathy patients with type 2 diabetes mellitus who underwent septal myectomy from two medical centers in China from 2011 to 2018. A propensity score–matched cohort of 134 patients without type 2 diabetes mellitus was also analyzed. Results: During a median follow-up of 28.0 (interquartile range: 13.0–3.0) months, 9 patients died. The cause of death of all of these patients was cardiovascular, particularly sudden cardiac death in 3 patients. Patients with type 2 diabetes mellitus had a higher rate of sudden cardiac death (4.5% vs. 0.0%, p = 0.04). The Kaplan–Meier survival analysis revealed that the rates of predicted 3-year survival free from cardiovascular death (98.1% vs. 95.1%, p = 0.14) were similar between the two groups. However, the rates of predicted 3-year survival free from sudden cardiac death (100% vs. 96.7%, p = 0.01) were significantly higher in hypertrophic cardiomyopathy patients without type 2 diabetes mellitus than in those with type 2 diabetes mellitus. Furthermore, after adjustment for age and sex, only N-terminal pro-brain natriuretic peptide (hazards ratio: 1.002, 95% confidence interval: 1.000–1.005, p = 0.02) and glomerular filtration rate ≤ 80 ml/min (hazards ratio: 3.23, 95% confidence interval: 1.34–7.24, p = 0.047) were independent risk factors for hypertrophic cardiomyopathy patients with type 2 diabetes mellitus. Conclusions: Hypertrophic cardiomyopathy patients with and without type 2 diabetes mellitus have similar 3-year cardiovascular mortality after septal myectomy. However, type 2 diabetes mellitus is associated with higher sudden cardiac death rate in these patients. In addition, N-terminal pro-brain natriuretic peptide and glomerular filtration rate ≤ 80 ml/min were independent risk factors among hypertrophic cardiomyopathy patients with type 2 diabetes mellitus. [ABSTRACT FROM AUTHOR]

Rationale: Monitoring plasma concentration and adjusting doses of antituberculosis (TB) drugs are beneficial for improving responses to drug treatment and avoiding adverse drug reactions. A simple and sensitive liquid chromatography/tandem mass spectrometry method was developed to measure the plasma concentrations of 14 anti‐TB drugs: ethambutol, isoniazid, pyrazinamide, levofloxacin, gatifloxacin, moxifloxacin, prothionamide, linezolid, rifampin, rifapentine, rifabutin, cycloserine, p‐aminosalicylic acid, and clofazimine. Methods: Human plasma was precipitated by acetonitrile and was subsequently separated by an AQ‐C18 column with a gradient elution. Drug concentrations were determined using multiple reaction monitoring in positive ion electrospray ionization mode. According to pharmacokinetic data of patients, the peak concentration ranges and the timing of blood collection were determined. Results: Intra‐ and interday precision was < 14.8%. Linearity, accuracy, extraction recovery, and matrix effect were acceptable for each drug. The stability of the method satisfied different storage conditions. Conclusions: The method allowed the sensitive and reproducible determination of 14 frequently used anti‐TB drugs which has already been of benefit for some TB patients. [ABSTRACT FROM AUTHOR]

User reliability is notably crucial for personalized cloud services. In cloud computing environments, large amounts of cloud services are provided for users. With the exponential increase in number of cloud services, it is difficult for users to select the appropriate services from equivalent or similar candidate services. The quality-of-service (QoS) has become an important criterion for selection, and the users can conduct personalized selection according to the observed QoS data of other users; however, it is difficult to ensure that the users are reliable. Actually, unreliable users may provide unreliable QoS data and have negative effects on the personalized cloud service selection. Therefore, how to determine reliable QoS data for personalized cloud service selection remains a significant problem. To measure the reliability for each user, we present a cloud service selection framework based on user reputation and propose a new user reputation calculation approach, which is named MeURep and includes L1-MeURep and L2-MeURep. Experiments are conducted, and the results confirm that MeURep has higher efficiency than previously proposed approaches. [ABSTRACT FROM AUTHOR]

Superconductivity beyond electron-phonon mechanism is always twisted with magnetism. Based on a new field-effect transistor with solid ion conductor as the gate dielectric (SIC-FET), we successfully achieve an electric-field-controlled phase transition between superconductor and ferromagnetic insulator in (Li,Fe)OHFeSe. A dome-shaped superconducting phase with optimal T c of 43 K is continuously tuned into a ferromagnetic insulating phase, which exhibits an electric-field-controlled quantum critical behavior. The origin of the ferromagnetism is ascribed to the order of the interstitial Fe ions expelled from the (Li,Fe)OH layers by gating-controlled Li injection. These surprising findings offer a unique platform to study the relationship between superconductivity and ferromagnetism in Fe-based superconductors. This work also demonstrates the superior performance of the SIC-FET in regulating physical properties of layered unconventional superconductors. [ABSTRACT FROM AUTHOR]