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Early and accurate diagnosis of Alzheimer's disease is beneficial to both preserve daily functioning and test possible new treatments. However, current diagnosis depends on dozens of factors, including the family member, past medical problems, tests of memory, blood and urine tests, brain scans and even cerebrospinal fluid specimens. Among them, regular features (e.g., blood and urine tests, brain...
Brain tumors, especially high-grade gliomas, are one of the most lethal cancers for humankind today. Early and accurate diagnosis of tumor grading is the key for subsequent therapy and treatment. In the past, conventional computer-aided diagnosis relies on handcrafted features from magnetic resonance images (MRI), which are usually inaccurate and laborious. Recently, deep neural networks have been...
An all-optical phase shifter near 1550nm is realized by depositing two-dimension nanomaterial tungsten disulfide (WS2) to tapered fiber. All-optical switch and modulator are also demonstrated by embedding the phase shifter to a Mach-Zehnder interferometer.
In the wireless sensor network, the nature of sensor nodes has a direct impact on the network life cycle. In order to improve the energy efficiency of nodes and extend the network lifetime, WSN acquisition nodes are studied. SAW based on a micro force sensor is used as a sensor node, and the frequency and pressure transformation model of SAW sensors is established by the principle of least squares...
The speed of the target can be estimated by the sound pressure cross-correlation of the line spectrum of the moving target at different time intervals. However, a slight deviation of the line spectrum has a significant influence on the estimated result. In this paper this phenomenon is analyzed from the theory, then the speed of the target is estimated when the line spectrum is biased. Experimental...
Reverberation is the main interference in active sonar detection, due to its special properties, reverberation suppression is a difficult problem in active sonar signal processing. In this paper, the method of reverberation suppression is studied, and a new method based on the normalization of the beam space data is proposed. The basic idea of this method is to normalize the time waveform of the beam...
An improved front-end processing circuit for bioelectrical signal acquisition is proposed for high common mode rejection ratio. The proposed circuit consists of three parts, bias voltage divider, ADC process unit and virtual driven-right-leg circuit. Through partial public DC bias circuit and virtual right leg drive circuit, common mode rejection ratio of the circuit can be improved effectively, as...
A novel discrete sinusoidal signal integrator (DSSI) structure is proposed in this paper for single grid-tied inverters. The DSSI provides an adjustable gain and bandwidth at the expected frequency and a highly attenuated gain at other frequencies which make the DSSI based controllers obtain the zero steady-state error tracking performance of arbitrary frequencies. The performance of the conventional...
To improve the reliability of wind turbines, various condition monitoring systems (CMSs) have been developed and most of them transmit data using wired communication channels. Recently, wireless sensor networks (WSNs) have been used to transmit data in wind turbine CMS due to the low cost and easy deployment feature of WSNs. However, since wind turbines are installed in harsh environments, the sensors...
Sparse representation of massive condition monitoring signals is an effective approach to save the cost for data storage and transmission in fault diagnosis of wind turbines. This paper explores a sparse representation method over a new dictionary designed particularly for bearing vibration signals of wind turbines operating under varying-speed conditions. First, the time-varying shaft rotating frequency...
In this paper, the design and operation of two 650 V/ 60 A Gallium Nitride (GaN) devices in parallel is discussed in detail, further, the challenges faced and the trade-offs required for paralleling high speed GaN devices are also examined. The dynamic characterization of two devices in parallel is presented in detail. The phase leg design requires both power loops and gate loops to be as small and...
Although the hybrid switch consisting of high power Si IGBT and low power SiC MOSFET achieves reduction of losses and cost, there is a severe concern of its short-circuit capability due to its internal SiC MOSFET with small die size. Experimental study shows that the short-circuit capability of hybrid switch is limited by that of SiC MOSFET. The physical mechanism of short-circuit capability of SiC...
This paper presents an analytical model to provide a rapid estimation of the steady-state averaged power loss of a T-type STATCOM with Virtual Zero level Modulation (VZM) to balance the neutral point voltage. A case study is then conducted on a 54kVA rated T-type STATCOM system to investigate the power loss distribution over power devices and variations over switching frequency. A comparison is made...
The dynamic characteristic, stability characteristic, and power sharing situation of the distributed system based on traditional droop control strategy are easily affected by uncontrollable power coupling and difference of line impedance of the distributed generator (DG) units in distributed system. In order to solve these drawbacks, an improved droop control strategy is proposed. It introduces the...
Fault diagnosis of drive train gearboxes is a prominent challenge in wind turbine condition monitoring. Many machine learning algorithms have been applied to gearbox fault diagnosis. However, many of the current machine learning algorithms did not provide satisfactory fault diagnostic results due to their shallow architectures. Recently, a class of machine learning models with deep architectures called...
This paper proposes a direct torque control strategy for a brushless dc (BLDC) motor with a single sided matrix converter (SSMC) for an electrohydrostatic actuator system in aerospace application. A hybrid two- and three-phase switching mode is applied to minimize torque ripples during commutation. A six-phase SSMC is investigated and the simulation results are presented. Compared with current hysteresis...
Taken the high voltage SF6 circuit breaker (HV SF6 CB) as the research object, a novel axial vortex chamber structure with an “X-type” guide blade constructed at the nozzle is proposed to exchange the energy of the turbulent gas flow in the radial direction during the interruption and to control the gas flow temperature gradient. The 3D flow field physical and mathematical model of the arc quenching...
In railway traction applications, due to the limitation of switching frequency and the attempt to fully utilize the DC-link voltage, the traction inverters usually work in six-step (or quasi-square-wave) mode under heavy load or high frequency condition. Meanwhile, DC-link voltage fluctuation, stemming from a common single-phase grid-side power supply, has a great impact on the drive system. To maintain...
The intuitionistic fuzzy set which is characterized by a membership degree and a non-membership degree, is a very powerful and useful tool to cope with fuzziness and uncertainty. Recently, the Pythagorean fuzzy set which is an extension of the intuitionistic fuzzy set has been introduced. In this paper, we focus on multi-attribute decision making with Pythagorean fuzzy information. First of all, considering...
In recent years, many online health communities (OHCs) are established to provide the patients with the services of disease prevention and self-management. Patients in those online health communities discuss their health conditions and share their experiences with other patients using narrative texts in the posts. Those posts contain a vast amount of patients' information, including drugs, symptoms,...
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