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• This paper presents an effective approach for coupling relationship analysis in multiple differently parameterized inverters. • All system resonance cases and phenomena are presented. • The proposed method is suitable for all multi-inverter parallel structures. This study investigates the coupling problem between different types of resonances in the system of multiple differently parameterized inverters. The coupling between the inverters and the grid, as well as between differently parameterized inverters, can lead to different types of resonances, which have different resonance characteristics. Due to the absence of resonance coupling relationship analysis, it is difficult to form a unified and complete understanding of the system resonances that are formed by the superposition of different types of resonances. In this paper, the system model is established, and the expressionsof the interactive current circulating between the parallel inverters and input-grid current injecting the power grid can be obtained. Stability analysis of the interactive current and input-grid current reveal characteristics of different types of resonances, and thus the resonance coupling relationship is obtained. It helps to form a complete understanding of system resonance characteristics, and then obtain all system resonance cases. The effects of system parameters on the resonance characteristics and harmonic interaction are analyzed. Finally, the correctness of the theoretical analysis is validated through simulations and experiments. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is a vital gas signaling molecule that performs crucial physiological functions in biological systems, and it can also cause food safety problems. In this study, we developed a cyanine derivative-based mitochondrial-targeted near-infrared fluorescent probe PC-H 2 S for detecting H 2 S. When PC-H 2 S reacted with H 2 S, it reached maximum fluorescence intensity at 656 nm and detection limit as low as 34 nM, and exhibited strong chromogenic response from green to red for H 2 S. Moreover, PC-H 2 S could be utilized to identify H 2 S generated during food spoilage and thus monitored the process of food spoilage. More significantly, PC-H 2 S showed excellent mitochondrial targeting capabilities and endogenous/exogenous H 2 S imaging of living cells and zebrafish could be performed. As a result, this research provides an attractive method for detecting H 2 S in food and biological systems and has potential value in physiopathological research. [Display omitted] • A cyanine derivative-based mitochondrial-targeted NIR fluorescent probe PC-H 2 S for detecting H 2 S was developed. • PC-H 2 S had a low detection limit and exhibited strong chromogenic response from green to red for H 2 S in naked eyes and UV light. • PC-H 2 S test strips was capable of monitoring H 2 S produced by food spoilage. • PC-H 2 S could be used for living cells and zebrafish imaging. [ABSTRACT FROM AUTHOR]

• Studied the distribution characteristics of six heavy metals in four anaerobic digestion system. • Effects of substrate types on the transformation of heavy metal speciation was investigated. • The mechanism leading to the transformation of heavy metal speciation was hypothesized. Chemical speciation can fundamentally affect the potential toxicity and bioavailability of heavy metals. The transformation of heavy metal speciation and change of bioavailability were investigated in an anaerobic digestion (AD) system using four different substrates (pig manure (PM), cattle manure (CAM), chicken manure (CHM) and rice straw (RS)). The results obtained indicated that the total contents of heavy metals in PM, CHM and CAM were higher than in RS and decreased in the order Zn > Cu > Ni > Pb > As > Cd in all substrates. Moreover, the speciation with the largest proportion for each heavy metal was the same both in the different substrates and the biogas residues. Among them, Zn, Ni, Cd and As were mainly in the reducible fraction (F2), while Cu was mainly in the oxidizable fraction (F3) and Pb occurred predominantly in the residual fraction (F4). Our results further indicated that the AD process had a greater effect on the speciation of heavy metals in CHM and PM, but less on CAM and RS. The rates of change in bioavailability followed the order PM > CHM > CAM > RS. Changes in organic matter, humic acid or local metal ion environment as a result of AD were inferred as likely mechanisms leading to the transformation of heavy metal speciation. These results enhanced our understanding of the behavior of heavy metals in AD and provided a new perspective for the treatment and disposal of the substrates. Image, graphical abstract [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]

Objective To study the curative effect and prognosis of patients with basal ganglia cerebral hemorrhages treated using a transcortical-sulcus approach and compare with results obtained using the traditional cerebral cortex approach. Methods Clinical data were collected from 106 patients with hypertensive hemorrhage in the basal ganglia who were treated using either a transcortical-sulcus approach or traditional cerebral cortex approach. The rate of rehemorrhage, incidence of epilepsy, and 3-month efficacy (defined by an activities of daily living score) rate between the 2 groups were compared. Results The 3-month efficacy rates of patients treated using the transcortical-sulcus and traditional cerebral cortex surgical approaches were 78.4% and 60%, respectively ( P < 0.05). The incidence of epilepsy was lower in the transcortical-sulcus approach group compared with the traditional approach group, and significant differences were detected between the 2 groups ( P < 0.05). Conclusions The transcortical-sulcus approach can significantly improve the prognosis of patients with intracerebral hemorrhages in the basal ganglia and reduce the incidence of postoperative seizures. [ABSTRACT FROM AUTHOR]

Power semiconductors in the wind turbine power converter system suffer from two-scale thermal loadings, the fundamental frequency thermal cycling caused by the output frequency of converter and the low frequency thermal cycling due to the variation of long-term wind speed. These two-scale thermal loadings introduce different consumed lifetimes. Accurate lifetime estimation in the wind power application is desired for reliability prediction and health management. This paper adopts the Bayerer lifetime model to evaluate the consumed lifetime of power semiconductors in wind power converter systems based on a numerical junction temperature calculation method. Lifetime estimation can be improved by taking into account the ambient temperature. Studies show that fluctuations of the ambient temperature increase the consumed lifetime due to the low frequency thermal cycling, but have little effect on the consumed lifetime due to the fundamental frequency thermal cycling. Our results also show that the consumed lifetime due to fundamental frequency thermal cycling mainly falls on the high wind speed area, whereas the consumed lifetime due to low frequency thermal cycling is clustered in the area due to large low frequency junction temperature fluctuations. The resulting distribution characteristics can be used in the thermal management for reliability improvement. [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]

Synchronization with the grid voltage is critical in the control of grid-connected power converters. Under unbalanced grid condition, the conventional synchronous reference frame phase-locked loop (SRF-PLL) does not work well due to the effect of the fundamental negative sequence component. This paper proposes a new synchronization method, the sinusoidal amplitude integrator based phase locked loop (SAI-based PLL), to efficiently eradicate the effect of the fundamental negative sequence component. As a result, it can accurately and quickly estimate the amplitude and phase angle of the fundamental components of grid voltages in unbalanced grid conditions. In addition, when dc offset and harmonics are contained in the grid voltage, a multi-SAI-based PLL method is developed to extract the synchronization signal. The proposed SAI-based PLL incorporates the sinusoidal amplitude integrator into the conventional SRF-PLL. Its operation is analyzed using the complex-vector notation. Simulation and experimental results on the performance of the proposed SAI-based PLL and comparison with other synchronization methods are presented. [ABSTRACT FROM AUTHOR]

Competing Interests: Conflict of interest The authors declare that they have no conflict of interest.