Inter‐blade cavitation vortex at part load has raised significant concerns about operation stability for Francis turbines due to tremendous development and integration of renewable energy resources ...into power grid. The principal objective of this study is to investigate the flow characteristics of inter‐blade cavitation vortex and its influence on pressure fluctuations for a low‐head Francis model turbine. Unsteady numerical simulations are carried out using shear stress transport turbulence model and Zwart cavitation model. Numerical results yield to a good validation with the experimental data. The findings show that inter‐blade cavitation vortices highlighted by cavitation structure and vortex structure are extremely different at the points adjacent to the incipient line of inter‐blade cavitation vortex. The location of inter‐blade cavitation vortex development in the runner is more sensitive to rotating speed than that to guide vane opening. The formation mechanism of inter‐blade cavitation vortex is attributed to flow separation in the vicinity of the runner hub. Pressure fluctuations induced by inter‐blade cavitation vortex are directly associated with the evolution of vapour volume in the runner and feature wide‐band and low‐frequency characteristic, and the fluctuations on the suction side of the runner blade are significantly magnified because of the presence of inter‐blade cavitation vortex.
The single-core alternating current (AC) submarine cable can be provided with an outer sheath that is firmly grounded on both ends of the cable. The circulating currents of the outer sheath are ...generated to be almost as large as the conductor current. The outer sheaths, which have different structures and properties, generate unwanted losses, asymmetric distribution of circulating current, and extra heat in the single-core AC submarine cables. The formation mechanism of the circulating currents in the submarine cable sheath and armoring is analyzed from the perspective of electromagnetic shielding using electromagnetic transient theoretical analysis, simulation calculation, and field experiments. Equations for calculating the circulating currents of the sheath and armoring are proposed, and influences of these relationships that include the different material characteristics of the sheath and armoring are analyzed. The influence factors, which include different levels of magnetic armoring permeability, resistivity, and ground resistance of the outer sheath, can affect the symmetrical distribution of the circulating current in the outer sheaths. We propose using the phase differences to determine the material properties of each metallic section in the submarine cable.
Balloon flower root-derived exosome-like nanoparticles (BDEs) have recently been proposed as physiologically active molecules with no cytotoxicity. However, the therapeutic effects of drug-induced ...hepatotoxicity of BDEs have not been elucidated. BDEs contain a large amount of platycodin D, which is widely known to be effective in regulating inflammation and ameliorating systemic toxicity. Thus, the main therapeutic activity of BDEs is attributed to inhibiting the inflammatory response and alleviating toxicity. In this study, we fabricated the hybrid BDEs fused with liposomes containing silymarin (SM) to enhance the synergistic effect on inhibition of acetaminophen-induced hepatotoxicity (APAP). Considering the potential therapeutic effects of BDEs, and the potential to achieve synergistic effects to improve therapeutic outcomes, we constructed hybrid BDEs with a soy lecithin-based liposome loaded with SM. Since liposomes can provide higher thermal stability and have greater structural integrity, these might be more resistant to clearance and enzymatic degradation of drug molecules. Hybrid BDEs with liposome-loaded SM (BDEs@lipo-SM) were fabricated by thin-film hydration and extrusion. BDEs@lipo-SM were characterized using dynamic light scattering and high-performance liquid chromatography. After confirmation of the physical properties of BDEs@lipo-SM, various therapeutic properties were evaluated. BDEs@lipo-SM were internalized by hepatocytes and immune cells and significantly decreased mRNA expression of apoptosis and inflammation-relevant cytokines by inhibiting the hepatocyte MAPK pathway. BDEs@lipo-SM significantly induced an increase in glutathione levels and inhibited APAP-induced hepatotoxicity. From this study, we know that BDEs are reliable and safe nanovesicles containing natural metabolites derived from balloon flower, and they can facilitate intercellular communication. BDEs are also easily modified to enhance drug loading capacity, targeting effects, and long-term accumulation in vivo. BDEs@lipo-SM have therapeutic benefits for acute liver injury and can alleviate cell death and toxicity. They can be efficiently delivered to the liver and effectively inhibit APAP-induced hepatotoxicity by inhibiting the MAPK signaling pathway and apoptosis, which accelerates liver recovery in the APAP-induced acute liver injury model. These findings highlight that BDEs represent an attractive delivery vehicle for drug delivery.
This paper proposes a distributed RS coding scheme to construct a subcode at the destination. Practically in any distributed coding scheme, an appropriate encoding strategy at the relay plays a vital ...role in achieving an optimized code. Therefore, the authors have proposed an efficient approach for proper selection of information at the relay based on subspace approach. Using this approach as the proper benchmark, another more practical selection approach with low complexity is also proposed. Monte Carlo simulations demonstrate that the distributed RS coding scheme under the two approaches can achieve nearly the same bit error rate performance. Furthermore, to jointly decode the source and relay codes at the destination, two different decoding algorithms named as naive and smart algorithms are proposed. The simulation results reveal that the advantage of smart algorithm as compared to naive one. The proposed distributed RS coding scheme with smart algorithm outperforms its non-cooperative scheme by a gain of 2.4–3.2 dB under identical conditions. Moreover, the proposed distributed RS coding scheme outperforms multiple existing distributed coding schemes, making it an excellent candidate for the future distributed coding wireless communications.
Fluid viscosity is one of the key factors affecting the cavitation characteristics of the Helico-axial Multiphase Pump (HAMP). In this paper, fluids with viscosities of 24.46 mm2/s, 48.48 mm2/s, ...60.70 mm2/s, and 120.0 mm2/s were investigated by numerical simulation. The Ansys Fluent software was employed to conduct the simulation. The mixture multiphase flow model and the RNG k-ε turbulence model were adopted. The Singhal cavitation model was employed to consider the effects of the non-condensable gas on cavitation. An experiment was carried out to validate the numerical method. The results showed that the Net Positive Suction Head-available (NPSHA) of the pump decreased as the fluid viscosity increased. Under the critical NPSHA condition, the NPSHA decreased from 5.11 m to 3.68 m as the fluid viscosity increased from 24.46 mm2/s to 120.0 mm2/s. This suggested that the cavitation performance of the pump was deteriorated under high fluid viscosity. The impeller passage area occupied by the vapor increased when the fluid viscosity increased. Nearly half of the flow passages were occupied by cavitation bubbles when the fluid viscosity increased to 120.0 mm2/s. The vapor volume fraction, both on the suction surface and pressure surface of the blade, increased with the fluid viscosity. The vapor on the suction surface was mainly distributed in the region with the streamwise between 0 and 0.36 when the fluid viscosity was 24.46 mm2/s; while the high vapor volume fraction range increased to the streamwise of 0.42 when the fluid viscosity increased to 120.0 mm2/s. The higher vapor volume fraction corresponded with the lower pressure. It was also found that the turbulent kinetic energy, both on the suction surface and pressure surface, increased with the fluid viscosity, which was the favorite for producing more cavitation bubbles. Furthermore, the maximum velocity area was mainly concentrated in the inlet area of the impeller. The velocity distribution in the impeller was basically the same with the viscosity of 24.46 mm2/s and 48.48 mm2/s. When the viscosity further increased to 60.70 mm2/s, the maximum velocity area in the impeller was relatively large. This study provides a reference for designing the HAMP.
The monotonic tensile properties and deformation mechanisms of Fe–Mn–C twinning-induced plasticity (TWIP) steels have been extensively studied; however, the low-cycle fatigue (LCF) properties of this ...series of advanced steels have not been well understood. The present paper addresses the cyclic deformation behavior and the deformed microstructure of an as-annealed TWIP steel. Fully reversed push–pull LCF tests were performed at room temperature under total strain amplitude control with a strain rate of 0.006s−1 and strain amplitudes ranging from 0.002 to 0.01. The results show initial rapid cyclic hardening within the initial 10% of the fatigue life at all strain amplitudes, and demonstrate an obviously enhanced cyclic yield strength. Different types of cyclic stress responses were revealed, which are featured by initial cyclic hardening followed by cyclic saturation, or followed by cyclic softening and saturation, or followed by cyclic softening without saturation till the final fracture, depending on the strain amplitude applied. The microstructure prior to and after fatiguing were examined by means of optical and transmission electron microscopy. The typical optical microstructure of fatigued samples is characterized by increases in slip band density with increasing strain amplitude or number of cycles at a given strain amplitude applied. The substructures of the deformed samples are featured by the formation of stacking faults and vein/labyrinth dislocation structures, while fine twins and cell or wall dislocation structures, besides those generated at lower strain amplitudes, are formed at high strain amplitudes.
This paper proposes the distributed Reed–Solomon (RS)-coded spatial modulation (DRSC-SM) scheme over quasi-static Rayleigh fading channel. Two different RS codes are used, one having a smaller ...minimum distance at the source and the other having a larger minimum distance at the relay. In order to obtain an optimized code at the destination, a proper encoding strategy must be adapted at the relay. Thus, an efficient design approach is proposed that suitably selects the symbols at the relay. Using this optimized approach as a benchmark, another design is proposed to achieve reduced complexity. To jointly decode the source and relay RS codes, three different decoding algorithms known as the naive, smart and improved smart algorithms are presented. Monte Carlo simulated results reveal that the proposed DRSC-SM scheme utilizing the improved smart decoding algorithm outperforms its counterpart DRSC-SM scheme employing the naive and smart decoding algorithms under identical conditions. The simulation results also validate the superiority of the proposed DRSC-SM scheme over its corresponding coded noncooperative scheme under the same decoding algorithm.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Previous studies have primarily focused on the influence of temperature and precipitation on phenology. It is unclear if the easily ignored climate factors with drivers of vegetation growth can ...effect on vegetation phenology. In this research, we conducted an analysis of the start (SOS) and end (EOS) of the growing seasons in the northern region of China above 30°N from 1982 to 2014, focusing on two-season vegetation phenology. We examined the response of vegetation phenology of different vegetation types to preseason climatic factors, including relative humidity (RH), shortwave radiation (SR), maximum temperature (Tmax), and minimum temperature (Tmin). Our findings reveal that the optimal preseason influencing vegetation phenology length fell within the range of 0-60 days in most areas. Specifically, SOS exhibited a significant negative correlation with Tmax and Tmin in 44.15% and 42.25% of the areas, respectively, while EOS displayed a significant negative correlation with SR in 49.03% of the areas. Additionally, we identified that RH emerged as the dominant climatic factor influencing the phenology of savanna (SA), whereas temperature strongly controlled the SOS of deciduous needleleaf forest (DNF) and deciduous broadleaf forest (DBF). Meanwhile, the EOS of DNF was primarily influenced by Tmax. In conclusion, this study provides valuable insights into how various vegetation types adapt to climate change, offering a scientific basis for implementing effective vegetation adaptation measures.
Auxin response factor (ARF) is a member of the plant-specific B3 DNA binding superfamily. Here, we report the results of a comprehensive analysis of ARF genes in allotetraploid Brassica napus (2n = ...38, AACC). Sixty-seven ARF genes were identified in B. napus (BnARFs) and divided into four subfamilies (I-IV). Sixty-one BnARFs were distributed on all chromosomes except C02; the remaining were on Ann and Cnn. The full length of the BnARF proteins was highly conserved especially within each subfamily with all members sharing the N-terminal DNA binding domain (DBD) and the middle region (MR), and most contained the C-terminal dimerization domain (PBI). Twenty-one members had a glutamine-rich MR that may be an activator and the remaining were repressors. Accordingly, the intron patterns are highly conserved in each subfamily or clade, especially in DBD and PBI domains. Several members in subfamily III are potential targets for miR167. Many putative cis-elements involved in phytohormones, light signaling responses, and biotic and abiotic stress were identified in BnARF promoters, implying their possible roles. Most ARF proteins are likely to interact with auxin/indole-3-acetic acid (Aux/IAA) -related proteins, and members from different subfamilies generally shared many common interaction proteins. Whole genome-wide duplication (WGD) by hybridization between Brassica rapa and Brassica oleracea and segmental duplication led to gene expansion. Gene loss following WGD is biased with the An-subgenome retaining more ancestral genes than the Cn-subgenome. BnARFs have wide expression profiles across vegetative and reproductive organs during different developmental stages. No obvious expression bias was observed between An- and Cn-subgenomes. Most synteny-pair genes had similar expression patterns, indicating their functional redundancy. BnARFs were sensitive to exogenous IAA and 6-BA treatments especially subfamily III. The present study provides insights into the distribution, phylogeny, and evolution of ARF gene family.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Radar ground target recognition technology is an important technical base for intellectualization and informatization of radar seeker of air-to-ground missile. Recently, ground target recognition ...technology has been paid much attention by researchers. However, with the increasingly fierce offensive and defensive confrontation in modern war, the application of radar ground target recognition technology is facing many problems, which has become a bottleneck factor restricting the development of weapons for a long time. To ensure that relevant radar practitioners better understand the development and future trend of this field, this paper introduces the conception of radar target recognition technology, and summarizes the technical difficulties of radar ground target recognition for equipment application. Afterwards, the research status at home and abroad are reviewed. Finally, the development trend of this technology is prospected.
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