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Endoscopic ultrasonography (EUS) has been found to be of great advantage in the diagnosis of digestive tract submucosal tumors. However, EUS-based diagnosis is limited by variability in subjective interpretation on the part of doctors. Tumor classification of ultrasound images with the computer-aided diagnosis system can significantly improve the diagnostic efficiency and accuracy of doctors. In this study, we proposed a multifeature fusion classification method for adaptive EUS tumor images. First, for different ultrasound tumor images, we selected the region of interest based on prior information to facilitate the estimation in the subsequent works. Second, we proposed a method based on image gray histogram feature extraction with principal component analysis dimensionality reduction, which learns the gray distribution of different tumor images effectively. Third, we fused the reduced grayscale features with the improved local binary pattern features and gray-level co-occurrence matrix features, and then used the multiclassification support vector machine. Finally, in the experiment, we selected the 431 ultrasound images of 109 patients in the hospital and compared the experimental effects of different features and different classifiers. The results revealed that the proposed method performed best, with the highest accuracy of 96.18% and an area under the curve of 99%. It is evident that the method proposed in this study can efficiently contribute to the classification of EUS tumor images. [ABSTRACT FROM AUTHOR]

With the development of switching power supply and electronic technology, the demand for portable electronics is constantly moving towards miniaturization, high-frequency, and low-power loss. This demand has put forward new requirements and challenges for the performance of multilayer chip power inductor. FeSiCr iron-based soft magnetic materials are widely used in the preparation of high-quality multilayer chip power inductor due to their higher magnetic permeability, quality factor Q, and oxidation resistance. However, the sintering conditions of the FeSiCr material have a significant impact on the performance of the multilayer chip power inductor. Currently, few of the reported study have considered the influence of oxygen partial pressure on the performance of multilayer alloy chip power inductor during sintering process. This paper studied the influencing factors of atmosphere sintering pretreatment temperature and time, sintering temperature and oxygen partial pressure during sintering process, based on the multilayer chip power inductor with the size of 201610. The formation mechanism of the influence curves has been comprehensively analyzed theoretically, and Maxwell FEM simulation was used to obtain the magnetic density distribution of the inductor. Finally, the best sintering conditions of the FeSiCr multilayer chip power inductor have been found. According to the comparative experimental under different sintering conditions, the following conclusions can been obtained: the appropriate adhesive discharge temperature and time are 350℃ and 60 minutes, respectively, the optimal sintering temperature is around 750 ℃, the optimal temperature rise rate is 5℃/min. While the oxygen partial pressure is about 6.5%, the multilayer inductor can obtain excellent electrical properties. [ABSTRACT FROM AUTHOR]

IGBT power module is the key component of the power electronic converter, but it has the lowest reliability. The junction temperature is the crucial factor which affects power module’s reliability. To some extent, the power handling capability of the converter depends on the thermal stress of the power module. Thermal management is an effective method to improve the reliability of power device, as well as enhance the power capability. For this purpose, this paper introduces the reliability design to the power converter’s traditional compensation controller design for the first time. A new concept of generalized dual-loop controller, which includes temperature control loop and electric power control loop, is proposed. The reliability and stability of the system are both considered, with the help of the hybrid controller, the power converter can operate steadily with higher reliability. The novelty of this paper is to improve the thermal control method of carrier frequency adjustment through experimental implementation during the full life cycle of the converter. The target is to control the temperature variation to be almost a constant value as well as extend the lifetime of the converter. IR sensor is used to measure the chip temperature of the unpackaged IGBT module. The temperature variation and the average temperature are all considered in thermal management, from the reliability improvement point of view. At last, the idea is digital implemented based on a varying load of power inverter system with real-time measurement of the chip’s surface temperature. [ABSTRACT FROM AUTHOR]

We successfully synthesized a novel core-shell hybrid metal oxide via a simple one-step hydrothermal method without annealing. This composite of Co 3 O 4 particles covered with SnO 2 –SnO (Co 3 O 4 @SnO 2 –SnO) predicted better performance compared to pure Co 3 O 4 , which strongly depends on the synthetic temperature. The Co 3 O 4 @SnO 2 –SnO prepared at a temperature of 250 °C (labeled Co 3 O 4 @SnO 2 –SnO-250) exhibited an outstanding specific capacitance of 325 F g−1 under the current density of 1 A g−1, which was much higher than those of Co 3 O 4 (12.6 F g−1) and other composites. Additionally, the sample also exhibited good cycle stability performance with a retention rate of 100% after 5000 cycles at a current density of 5 A g−1. Through X-ray photoelectron spectroscopy analysis, the presumed mechanism was that Sn-O x decreases the surface electron densities of Co 3 O 4 , which is beneficial to OH− adsorption and specific capacitance improvement, and the synthetic temperature had a strong impact on the microstructure and thus on the surface electron densities. The most. obvious finding to emerge from this study is that the specific capacitance can be improved through adjusting the surface electron densities of transition metal oxides. [ABSTRACT FROM AUTHOR]

In this paper, the ultrafine spherical FeSiAl soft magnetic composites were prepared by the particles coated with organosilane modified water-soluble silicone resin. The magnetic response of the sample fabricated with 15.36 μm particle is up to 358 MHz, and the real part of permeability exceeds 57. The P cv of this composite is just 604.85 kW/m3 and 606.44 kW/m3 at 200 kHz,100 mT and 1 MHz, 30 mT, respectively. In addition, the DC bias performance improved reaches to 61.3%, comparing to the sample fabricated by the large particles. The domain wall movement dominates the permeability when large particles are employed. However, the spin rotation plays a more important role in the case of small particles. Two stages with different loss mechanisms were investigated for different particle sizes. When the frequency exceeds 70 kHz, the declination of the insulating coating resistivity results in a loss jump, due to the space charge polarization. The FeSiAl crystalline termination at the grain boundary exhibits a symmetry break, thus resulting in a sharp local rise in the anisotropy field which provides a barrier to the domain wall motion and enhance the DC bias properties. This ultrafine FeSiAl composite shows great potential in the MHz magnetic power application. [Display omitted] • Spherical-FeSiAl soft magnetic composites were prepared. The magnetic response of the sample fabricated with 15.36 μm particle is up to 358 MHz. The P cv of this composite is just 604.85 kW/m3 and 606.44 kW/m3 at 200 kHz, 100 mT and 1 MHz, 30 mT, respectively. • It is found that the domain wall movement dominates the permeability when large particles are employed. However, the spin rotation plays a more important role in the case of small particles. • It also clarified a novel phenomenon that a sudden jump in loss curve at the frequency of near 70 kHz is observed for the short circuit of the insulating coating, due to the space charge polarization. • The electrochemical analysis demonstrates that this organosilane modified water-soluble silicone resin hybrid insulating layer can effective reduce the eddy current loss in high frequency. In this work, organosilane modified water-soluble silicone resin coated spherical-FeSiAl soft magnetic composites with different particle sizes were prepared, and the effects of the particle size on the permeability, magnetic loss, and DC bias were investigated. For large particles composite, multi-domain lead to the introduction of domain wall resonance, which restricts the permeability in low frequency. As the particle size decreases, the particles tend to be single domain particles resulting in a decrease of the domain wall resonance component and an enhancement of the spin rotation one. Two stages with different loss mechanisms were investigated and the sudden increase of the loss near 70 kHz is ascribed to the short circuit of the insulating coating in high frequency due to the space charge polarization. Furthermore, electrochemical analysis also demonstrates the insulation of this soft magnetic composite. This ultrafine FeSiAl composite may promote the development of MHz frequency semiconductor power devices. [ABSTRACT FROM AUTHOR]

A novel amorphous soft magnetic composites (ASMCs) for hundreds MHz frequency applications have been prepared under the hot-pressing molding by ultrafine submicron FeBP amorphous powders. These ultrafine submicron FeBP amorphous particles were synthesized with the NaBH 4 chemical reduction method and the particles size was regulated by the drop rate of the reducing agent. The morphology, microstructure, elemental composition and high-frequency magnetic properties of the amorphous soft magnetic composites was systematically investigated. The particle sizes of FeBP amorphous powders are distributed in 600–900 nm which gradually increase with the decrease of the drop rate of the NaBH 4 aqueous solution. Meanwhile, the Fe element content and saturation magnetization strength of the amorphous powder increase and the coercivity gradually decreases. The corresponded ASMCs also appear a commensurate permeability in the range of 6–9 responding to the GHz high frequency range with the lowest loss tangent only 0.20 and 0.44 at 500 MHZ and 1 GHz, respectively. Such ultrafine amorphous soft magnetic composites have enormous potential for high frequency applications in wide band gap semiconductor switching power supplies, RF inductors and chips. • The spherical amorphous powder was prepared by chemical reduction method with outstanding magnetic properties. • The particle size of the amorphous powder was regulated by adjusting the drop rate of the reducing agent solution. • The relationship between the powder particle size and the magnetic and electrical properties of ASMCs was elucidated. [ABSTRACT FROM AUTHOR]

Chip fatigue inside an insulated gate bipolar transistor (IGBT) module is a kind of incipient defect. It can be considered as an indication of the impending failure, and is utmost important for the safe operation of IGBT modules. Therefore, monitoring the chip fatigue is one of crucial measures to enhance the operating reliability of IGBT modules. This paper presents a prognostic approach for the chip fatigue based on grey relational analysis (GRA), which uses dynamic change of the gate voltage as precursor parameter. This dynamic change is caused by aging of the intrinsic parasitic elements involved in gate drive circuit, which reflect the advent of chip fatigue. Grey relational grade is employed in this proposed prognostic approach to quantify the extent of those dynamic changes by little data, and find out potential chip fatigue. Then the operator would have a chance to schedule the maintenance and replace defective IGBT modules timely to avoid wear out. So it can be seen as a prefault diagnostic method. Finally, a confirmatory experiment is also carried out, and the correctness of the proposed approach is verified. [ABSTRACT FROM AUTHOR]

• A novel hybrid amorphous soft magnetic composite (SMC) for MHz power applications is fabricated using amorphous powders of ultrafine spherical FeSiBCr and submicron FeBP powders. • The regularly spherical particles of submicron amorphous FeBP powders are found to occupy the gaps between the micron-sized FeSiBCr amorphous powders. • The magnetic loss of the soft magnetic composite mixed with only 1 wt% submicron amorphous FeBP particles is just 511 kW/m3 at 30 mT/1 MHz, and the permeability of DC bias superposition under 100 Oe reaches 90%. • The soft magnetic composite constructed by the pure submicron amorphous FeBP particles also shows excellent magnetic properties within a few hundred MHz region, with the permeability of 4–6 and the low loss tangent of only 0.019 at 200 MHz and 0.05 at 500 MHz. • This amorphous soft magnetic composite exhibits a great potential for the applications in wide band gap semiconductor switching power supplies, RF inductors and chips. A novel hybrid amorphous soft magnetic composite (SMC) for MHz power applications is fabricated using amorphous powders of ultrafine(<10 μm) spherical FeSiBCr and submicron(100 nm∼1 μm) FeBP powders. The submicron amorphous FeBP powders are found to occupy the gaps between the micron-sized FeSiBCr amorphous powders, enabling one to enhance the density and magnetic properties (permeability and loss) of the composite in a MHz frequency range. The magnetic loss of the soft magnetic composite mixed with only 1 wt% submicron amorphous particles is just 511 kW/m3 at 30 mT/1 MHz, and the permeability of DC bias superposition under 100 Oe reaches 90%. In addition, the permeability of the hybrid soft magnetic composite and the submicron amorphous composite reach 20 and 5, and the loss tangent is only 0.03–0.08 and 0.02 in 100 MHz region, respectively. This amorphous soft magnetic composite exhibits a great potential for the applications in wide band gap semiconductor switching power supplies. [ABSTRACT FROM AUTHOR]