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Abstract Although there are many methods to improve the fault ride‐through (FRT) capability of doubly‐fed induction generator (DFIG) systems at present, each method has its shortcomings, especially the applicability under different voltage dips (VDs), so an improved system structure with a dynamic switching topology and a corresponding control scheme is proposed. Based on the mechanism analysis that the series impedance of the stator can effectively reduce the overcurrent on the rotor side, and considering the feasibility of the FRT scheme in engineering, the dynamic switching topology is designed. The selection of theoretical parameters in different cases is also analysed and designed. Simultaneously, to cooperate with the hardware measures, the control scheme of the rotor side converter (RSC) under different conditions is also improved. The RSC can use the control scheme of active flux attenuation to effectively and quickly reduce the overcurrent on the rotor side, and use reactive power support to accelerate the voltage recovery. The novelty of the FRT scheme is that the scheme can dynamically adjust the topology structure and control scheme under different voltage dips. Thus, its ride‐through performance during fault is better under different conditions. A simulation model of the improved system structure and control scheme is built on the MATLAB/Simulink platform. Through the comparison of simulation data, the validity and correctness of the proposed FRT scheme are verified.

Objective Adequate vitamin and trace mineral intake for pigs are important to achieve satisfactory growth performance. There are no data available on the vitamin and trace mineral intake across pig producers in China. The purpose of this study was to investigate and describe the amount of vitamin and trace minerals used in Chinese pig diets. Methods A 1-year survey of supplemented vitamin and trace minerals in pig diets was organized in China. A total of 69 producers were invited for the survey, which represents approximately 90% of the pig herd in China. Data were compiled by bodyweight stages to determine descriptive statistics. Nutrients were evaluated for vitamin A, vitamin D, vitamin E, vitamin K, thiamine, riboflavin, vitamin B6, vitamin B12, pantothenic acid, niacin, folic acid, biotin, choline, copper, iron, manganese, zinc, selenium, and iodine. Data were statistically analyzed by functions in Excel. Results The results indicated variation for supplemented vitamin (vitamin A, vitamin D, vitamin E, vitamin K, vitamin B12, pantothenic acid, niacin, and choline) and trace minerals (copper, manganese, zinc, and iodine) in pig diets, but most vitamins and trace minerals were included at concentrations far above the total dietary requirement estimates reported by the National Research Council and the China’s Feeding Standard of Swine. Conclusion The levels of vitamin and trace mineral used in China’s pig industry vary widely. Adding a high concentration for vitamin and trace mineral appears to be common practice in pig diets. This investigation provides a reference for supplementation rates of the vitamins and trace minerals in the China’s pig industry.

Objective The present work was undertaken to evaluate the effects of storage time, choline chloride, and high concentrations of Cu and Zn on the kinetic behavior of vitamin degradation during storage in two vitamin premixes and four vitamin-trace mineral (VTM) premixes. Methods Two vitamin premixes (with or without 160,000 mg/kg of choline) were stored at 25°C and 60% humidity. Besides, four VTM premixes were used to evaluate the effects of choline (0 vs 40,000 mg/kg) and trace minerals (low CuSO4+ZnO vs high CuSO4+ZnO) on vitamin stability in VTM premixes stored in room, and the VTM premixes were stored in room temperature at 22°C. Subsamples from each vitamin and VTM premix were collected at 0, 1, 2, 3, 6, and 12 months. The retention of vitamin A (VA), vitamin D3 (VD3), vitamin E (VE), vitamin K3 (VK3), vitamin B1 (VB1), vitamin B2 (VB2), vitamin B3 (VB3), vitamin B5 (VB5), and vitamin B6 (VB6) in vitamin premixes and VTM premixes during storage was determined. The stability of vitamins in vitamin premixes and VTM premixes was determined and reported as the residual vitamin activity (% of initial) at each sampling point. Results The effect of choline on VK3 retention was significant in vitamin premixes (p

The interface plays a key role on the mechanical properties of Cf/SiC composite prepared by GSI process. The ideal interface should not only prevent carbon fiber from being etched by Si vapor, but also adjust the bonding force between C fiber and SiC matrix. SiC coating prepared by CVD was chosen as the interface and its effect on the mechanical properties and fracture features of GSI Cf/SiC composite was discussed, and the influencing mechanism was analyzed. The results show that GSI Cf/SiC composite without CVD-SiC interface has poor mechanical properties, exhibiting brittle fracture feature. The bending strength, elastic module and fracture toughness are 87.6MPa, 56.9GPa and 2.1MPa·m1/2, respectively. The mechanical properties of GSI Cf/SiC increase with the increase of the thickness of CVD-SiC coating at first, then decrease with the continuous increase of the thickness of CVD-SiC coating. The Cf/SiC composite with 1.1μm thickness of CVD-SiC coating has the best mechanical properties, and the bending strength, elastic module and fracture toughness are 231.7MPa, 87.3GPa and 7.3MPa·m1/2, respectively. The action mechanism of CVD-SiC interface coating on the composite is mainly on the three aspects:load transfer, preventing C fiber from being etched by Si and adjusting fiber/matrix bonding status.

C/C-SiC composites were prepared by the combined process of chemical vapor infiltration (CVI) and gaseous silicon infiltration (GSI) using C/C green body with the density of 1.0g/cm3. Effect of CVI C/C-SiC intermediate composites' density on the phase composition, microstructure and mechanical properties of CVI-GSI C/C-SiC composites was studied. The results show that as the CVI C/C-SiC intermediate composites' density increases, the residual C content increases and residual Si content decreases in the CVI-GSI C/C-SiC composites, the SiC content increases first and then decreases, and the density of CVI-GSI C/C-SiC composites increases first and then decreases; as the CVI C/C-SiC in termediate composites' density is increased from 1.27g/cm3 to 1.63g/cm3, the mechanical properties of CVI-GSI C/C-SiC composites increase at first, which then decrease with the further increasing of CVI-C/C-SiC composites' density. Specifically, when the CVI C/C-SiC composites density is 1.42g/cm3, the prepared CVI-GSI C/C-SiC composites has the best mechanical properties, with flexure strength, flexure modulus and fracture toughness of 247.50MPa, 25.63GPa and 10.08MPa·m1/2, respectively.

Cav3 channels consist of three isoforms, Cav3.1 (α1G), Cav3.2 (α1H), and Cav3.3 (α1I), which produce low-threshold spikes that trigger burst firings in nociceptive neurons of the spinal dorsal horn (SDH) and dorsal root ganglion (DRG). Although Cav3.2 plays a crucial role in pathological pain, its distribution in SDH still remains controversial. One study showed that Cav3.2 is ubiquitously expressed in neurons, but another study implied that Cav3.2 is expressed restricted to astrocytes. To unravel these discrepancies, we used methods of immunohistochemistry either with or without antigen retrieval (AR) pre-treatment to detect Cav3 in SDH and DRG from both rats and mice. Moreover, Cav3.2 mRNA was detected in mice SDH using in situ hybridization. We found that the expression pattern of Cav3.2 but not Cav3.1 and Cav3.3 in SDH were largely different with or without AR pre-treatment, which showed a neuron-like and an astrocyte-like appearance, respectively. Double staining further demonstrated that Cav3.2 was mainly co-stained with the neuronal marker NeuN in the presence of AR but was with glial fibrillary acidic protein (GFAP, marker for astrocytes) in the absence of AR pre-treatment. Importantly, Cav3.2 mRNA was mainly co-localized with Cav3.2 but not GFAP. Together, our findings indicate that AR pre-treatment or not impacts the expression pattern of Cav3.2, which may make a significant contribution to the future study of Cav3.2 in SDH.

The 3-D needled C/C preforms with different densities deposited by chemical vapor infiltration (CVI) method were used to fabricate C/C-SiC composites by gaseous silicon infiltration (GSI). The porosity and CVI C thickness of the preforms were studied, and the effects of preform density on the mechanical and thermal properties of C/C-SiC composites were analyzed. The results show that with the increase of preform density, the preform porosity decreases and the CVI C thickness increases from several hundred nanometers to several microns. For the C/C-SiC composites, as the preform density increases, the residual C content increases while the density and residual Si content decreases. The SiC content first keeps at a high level of about 40% (volume fraction), which then quickly reduces. Meanwhile, the mechanical properties increase to the highest values when the preform density is 1.085g/cm3, with the flexure strength up to 308.31MP and fracture toughness up to 11.36MPa·m1/2, which then decrease as the preform density further increases. The thermal conductivity and CTE of the composites, however, decrease with the increase of preform density. It is found that when the preform porosity is too high, sufficient infiltration channels lead to more residual Si, and thinner CVI C thickness results in the severe corrosion of the reinforcing fibers by Si and lower mechanical properties. When the preform porosity is relatively low, the contents of Si and SiC quickly reduce since the infiltration channels are rapidly blocked, resulting in the formation of large closed pores and not high mechanical properties.

In this work, Mn55Bi45-xBx (0 ≤ x ≤ 2) alloys were prepared by arc-melting, and the low-temperature ferromagnetic MnBi phase was investigated in 300 K. Through the XRD refinement results, it can be found that the lattice parameters of the alloys change with the B doping amount. When x = 1, an optimal room temperature spontaneous exchange bias effect was observed in the Mn55Bi44B. This phenomenon can be attributed to B with a smaller atomic radius occupying the Bi position, resulting in more Mn atoms into interstitial sites and more antiferromagnetic clusters on the ferromagnetic matrix. This work focuses on the effect of B doping on the structure and exchange bias behavior in Mn55Bi45 alloy, providing a way to design room temperature spintronic devices.

An intrinsically safe type electromagnet for underground hydraulic unloading valve was designed. The main technical indexes, performances and structure principle of the electromagnet were introduced, and selection of structure of the electromagnet was analyzed. The design of magnetic system of the electromagnet was expounded emphatically. The actual application showed that the electromagnet has features of small power, big suction and flexible action.

The purpose of this paper is to study sufficient and necessary conditions for finite-step iterative sequences with mean errors for a finite family of asymptotically quasi-nonexpansive and type mappings in Banach spaces to converge to a common fixed point. The results presented in this paper improve and extend the recent ones announced by Ghost-Debnath, Liu, Xu and Noor, Chang, Shahzad et al., Shahzad and Udomene, Chidume et al., and all the others.

Wavefront distortions pose a significant limitation in various optical applications, hindering further advancements in optical system performance. In this study, a novel generic calibration model based on Zernike‐fitting neural network (ZFNN) is proposed, which enables insitu wavefront correction with just a single‐shot measurement. The experimental setup follows a standard or equivalent focal‐field imaging optical path, allowing calibration without the need to remove any components from the optical system. The ZFNN, a physics‐informed neural network, offers the advantage of not requiring prior training, eliminating the need for extensive labeled data. With a fully connected network architecture and a modest number of neurons (469), the ZFNN achieves exceptionally fast optimization speed and meets the basic requirements for real‐time calibration. Consequently, this approach holds great potential for applications such as rapid calibration of optical systems, high‐precision light field modulation, and various advanced imaging techniques. [ABSTRACT FROM AUTHOR]

Panax notoginseng is a highly valued perennial medicinal herb in China and is widely used in clinical treatments. The main purpose of this study was to elucidate the changes in the composition of P. notoginseng saponins (PNSs), which are the main bioactive substances, triggered by arbuscular mycorrhizal fungi (AMF) via ultrahigh-performance liquid chromatography–electrospray ionization–tandem mass spectrometry (UPLC–ESI–MS/MS). A total of 202 putative terpenoid metabolites were detected, of which 150 triterpene glycosides were identified, accounting for 74.26% of the total. Correlation analysis, principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS–DA) of the metabolites revealed that the samples treated with AMF (group Ce) could be clearly separated from the CK samples. In total, 49 differential terpene metabolites were identified between the Ce and CK groups, of which 38 and 11 metabolites were upregulated and downregulated, respectively, and most of the upregulated differentially abundant metabolites were mainly triterpene glycosides. The relative abundances of the two major notoginsenosides (MNs), ginsenosides Rd and Re, and 13 rare notoginsenosides (RNs), significantly increased. The differential saponins, especially RNs, were more easily clustered into one branch and had a high positive correlation. It could be concluded that the biosynthesis and accumulation of some RNs share the same pathways as those triggered by AMF. This study provides a new way to obtain more notoginsenoside resources, particularly RNs, and sheds new light on the scientization and rationalization of the use of AMF agents in the ecological planting of medicinal plants. [ABSTRACT FROM AUTHOR]

Whole genome sequencing (WGS) plays an important role in the advanced characterization of pathogen transmission and is widely used in studies of major bacterial and viral diseases. Although protozoan parasites cause serious diseases in humans and animals, WGS data on them are relatively scarce due to the large genomes and lack of cultivation techniques for some. In this review, we have illustrated bioinformatic analyses of WGS data and their applications in studies of the genomic epidemiology of apicomplexan parasites. WGS has been used in outbreak detection and investigation, studies of pathogen transmission and evolution, and drug resistance surveillance and tracking. However, comparative analysis of parasite WGS data is still in its infancy, and available WGS data are mainly from a few genera of major public health importance, such as Plasmodium, Toxoplasma, and Cryptosporidium. In addition, the utility of third‐generation sequencing technology for complete genome assembly at the chromosome level, studies of the biological significance of structural genomic variation, and molecular surveillance of pathogens has not been fully exploited. These issues require large‐scale WGS of various protozoan parasites of public health and veterinary importance using both second‐ and third‐generation sequencing technologies. [ABSTRACT FROM AUTHOR]