Numerical Simulation Study on Propeller Slipstream Interference of High Altitude Long Endurance Unmanned Air Vehicle

AbstractIn this paper,thecontrol equation of Multiple Reference Frame(MRF) as the propeller calculation model was present and analyzed, the propeller slipstream interference on HALE UAV was studied with three-dimensional numerical simulation. It is shown that the flow field of the MRF model is good consistent with true propeller flow, and MRF can accurately simulate aerodynamic interference on the aircraft. The stream traces on the V-tail surface were deflected and shrank, pressure distribution,Cmx and Cmzon V-tail surface was changed apparently too.Butslipstream had little effect on wing. The influence of propeller slipstream on the aerodynamic performance of the UAV at the status of taking off is biggest, become weaker at status of climbing and smallest at the status of cruising. The influence of propeller slipstream is enhanced with increment of propeller thrust and basically familiar in the same thrust between the two blade attack angle. The pressure drag on aft of UAV fuselage increased rapidly by the interference of propeller slipstream, leading aerodynamic performance of UAV become badly

4-Cyclopropyl-1-(6′-deoxy-1′,2′-O-isopropylidene-α-d-glucofuranosyl)-1H-1,2,3-triazole

In the title compound, C14H21N3O5, the tetrahydrofuran ring adopts an envelope conformation with the C atom bearing the substituent as the flap. The pentafuranose ring adopts a twisted conformation about the C—C bond fusing the rings. The dihedral angle between these rings (all atoms), which are cis fused, is 72.89 (14)°. The cyclopropane ring is disordered over two orientations in a 0.576 (5):0.424 (5) ratio; the dihedral angles subtended to the triazole ring are 53.3 (11) and 46.6 (9)°, respectively. In the crystal, the molecules are linked by O—H...N and O—H...O hydrogen bonds, generating (001) sheets. A weak C—H...O interaction also occurs

Study of Aerodynamic Configuration Design and Wind Tunnel Test for Solar Powered Buoyancy-lifting Vehicle in the Near-space

AbstractAconfiguration of buoyancy-lifting vehicleflying in near-space by combinationthe configuration characteristics of high-altitude airships and solar UAV aerodynamic were proposed .Through the numerical simulation method, the aerodynamic configurations for solar powered buoyancy-lifting vehicle in near-space were investigated. High lift over drag ratio aerodynamic configuration was obtained by optimization design. Aerodynamic performance of the wing with low Reynolds in different altitude and drag performance of air cell fuselage with different generating line were analyzed, which change regulation were summarized. Aerodynamic configuration was tested in wind tunnel by cable mounting testing technology as well, results of aerodynamic coefficient from numerical simulation method and wind tunnel in different Reynolds number were according well, verified the reliability of design results from the numerical simulation method. The design method of aerodynamic configuration and wind tunnel test technology of solar powered buoyancy-lifting vehicle were created from this study. Significance guiding conclusion and experimental data to general design were obtained

1,2:1′,2′-Di-O-isopropylidenedifuranose-C12 higher carbon sugar

In the title compound, C18H28O8, the five-membered ring with one O atom attached to the ethyl substituent has a twisted conformation about the C—O bond. The adjacent cis-fused ring with two O atoms also has a twisted conformation about one of the C—O bonds. The dihedral angle between these rings (all atoms) is 59.05 (12)°. The five-membered ring linked to the ethynyl susbtituent is twisted about a C—C bond; the cis-fused adjacent ring is twisted about a C—O bond [dihedral angle between the rings (all atoms) = 71.78 (12)°]. Two intramolecular O—H...O hydrogen bonds occur. In the crystal, molecules are linked by O—H...O hydrogen bonds, generating [001] chains

Convolution Power Ratio Based on Single-Ended Protection Scheme for HVDC Transmission Lines

In order to solve the problems of insufficient abilities to withstand transition resistance under remote faults and difficulties in identifying internal and external faults for HVDC transmission line protection, a new single-ended protection scheme based on time-domain convolutional power was proposed. In this scheme, the ratio of time-domain convolution power at different frequencies is used to detect internal and external faults, and the long window convolution power is used to form the pole selection criteria. Due to the integration of transient power fault characteristics at high and low frequencies, this scheme amplifies the characteristic differences between internal and external faults caused by DC line boundaries and has a strong ability to withstand transition resistance. Based on PSCAD/EMTDC, simulation verification was conducted on the Yunnan–Guangzhou ±800 kV HVDC project. The results show that the proposed single-ended protection scheme can effectively identify fault poles, as well as internal and external faults. It has strong resistance to transition resistance and certain anti-interference ability and has strong adaptability to DC line boundaries, which meets the protection requirements of HVDC transmission systems for high speed, selectivity and reliability

Evaluation, Analysis and Diagnosis for HVDC Transmission System Faults via Knowledge Graph under New Energy Systems Construction: A Critical Review

High voltage direct current (HVDC) transmission systems play a critical role to optimize resource allocation and stabilize power grid operation in the current power grid thanks to their asynchronous networking and large transmission capacity. To ensure the operation reliability of the power grid and reduce the outage time, it is imperative to realize fault diagnosis of HVDC transmission systems in a short time. Based on the prior research on fault diagnosis methods of HVDC systems, this work comprehensively summarizes and analyzes the existing fault diagnosis methods from three different angles: fault type, fault influence, and fault diagnosis. Meanwhile, with the construction of the digital power grid system, the type, quantity, and complexity of power equipment have considerably increased, thus, traditional fault diagnosis methods can basically no longer meet the development needs of the new power system. Artificial intelligence (AI) techniques can effectively simplify solutions’ complexity and enhance self-learning ability, which are ideal tools to solve this problem. Therefore, this work develops a knowledge graph technology-based fault diagnosis framework for HVDC transmission systems to remedy the aforementioned drawbacks, in which the detailed principle and mechanism are introduced, as well as its technical framework for intelligent fault diagnosis decision

SLMO2 is a potential prognostic and immunological biomarker in human pan-cancer

Abstract SLMO2 is a lipid transporter that transports phosphatidylserine to the interior of mitochondria, also known as PRELID3B, which plays an important role in lipid metabolism. It has also been reported to be involved in the growth process of breast and lung tumors. However, its functions and underlying mechanisms in cancer progress remain elusive, and the potential as pan-cancer biomarker and therapeutic target remains unexplored. Using the TCGA project and GEO database, we performed pan-cancer analysis of SLMO2, which including the expression pattern, prognostic value, mutation landscape, methylation modification, protein–protein interaction network and the relationship between SLMO2 expression and immune infiltration. KEGG enrichment analysis was also performed to predict function and relevant cellular pathways of SLMO2. In addition, proliferation and migration assays were performed to detect the proliferation and metastasis capacity of breast cancer and lung cancer cells. In our study, we found that SLMO2 was overexpressed in pan-cancer and the elevated expression of SLMO2 was correlated with poorer prognosis. SLMO2 mutations were distributed in a variety of tumors and correlated with prognosis. Promoter methylation analysis showed that SLMO2 methylation levels were lower in most tumors compared with normal tissues, while a few tumors showed increased methylation levels of SLMO2. SLMO2 expression was also positively correlated with immune infiltration of MDSCs. Further pathway enrichment analysis indicated that SLMO2 was involved in regulating of cytoplasmic transport and other oncogenic processes. In vitro experiments have shown that SLMO2 promotes the proliferation and migration of breast cancer and lung cancer cells. In conclusion, our findings suggested that SLMO2 was a potential prognostic and immunological marker in pan-cancer. This study suggested a potential strategy for targeting SLMO2 to treat tumors, including manipulating tumor growth or the tumor microenvironment, especially the infiltration of MDSC