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Verification and Validation of High-Resolution Inviscid and Viscous Conical Nozzle Flows

Communications on Applied Mathematics and Computation 2024年第1期6卷 533-549页

作者： Luciano K.Araki Rafael B.de R.Borges Nicholas Dicati P.da Silva Chi-Wang Shu Department of Mechanical Engineering Federal University of ParanáCuritiba81531-980ParanáBrazil Mathematics and Statistics Institute Rio de Janeiro State UniversityRio de Janeiro20550-900Rio de JaneiroBrazil Department of Mechanical Engineering State University of MaringáMaringá87020-900ParanáBrazil Division of Applied Mathematics Brown UniversityProvidenceRI02912USA

Capturing elaborated flow structures and phenomena is required for well-solved numerical *** finite difference methods allow simple discretization of mesh and model ***,they need simpler meshes,e.g.,*** inverse Lax-Wendroff(ILW)procedure can handle complex geometries for rectangular ***-resolution and high-order methods can capture elaborated flow structures and *** also have strong mathematical and physical backgrounds,such as positivity-preserving,jump conditions,and wave propagation *** perceive an effort toward direct numerical simulation,for instance,regarding weighted essentially non-oscillatory(WENO)***,we propose to solve a challenging engineering application without turbulence *** aim to verify and validate recent high-resolution and high-order *** check the solver accuracy,we solved vortex and Couette ***,we solved inviscid and viscous nozzle flows for a conical *** employed the finite difference method,positivity-preserving Lax-Friedrichs splitting,high-resolution viscous terms discretization,fifth-order multi-resolution WENO,ILW,and third-order strong stability preserving *** showed the solver is high-order and captured elaborated flow structures and *** can see oblique shocks in both nozzle *** the viscous flow,we also captured a free-shock separation,recirculation,entrainment region,Mach disk,and the diamond-shaped pattern of nozzle flows.

关键词： High-resolution Compressible Navier-Stokes Free-shock separation Nozzle flow

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Investigation of the transformation of organic matter of carbonate deposits of the Semiluksky-Mendymsky horizon under hydrothermal conditions

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Petroleum 2024年第2期10卷 216-223页

作者： S.M.Petrov A.I.Lakhova E.G.Moiseeva A.G.Safiulina Institute of Petroleum Chemistry and Nanotechnologies Kazan National Research Technological University Institute of Geology and Oil and Gas Technologies Kazan Federal University

The paper presents the results of studies on the transformation of the organic matter of siliceous-clayey carbonate rocks of the Semiluksko-Mendymsky horizon of the Romashkino oil field in a hydrothermal fluid for an hour（with a water-to-rock ratio of 33） at 340℃ and 380℃ and pressu res of 17 and 20 *** a result of hydrothermal treatment,at 340℃ and 17 MPa,based on nitrogen porosimetry and electron microscopy data,transformations of rock-forming minerals in the rock are *** lead to an increase in the volume and average diameter of mesopores in it and the formation of micropores,as well,which improve its filtration *** the same time,the amount of kerogen in the composition of the organic matter decreases and the yield of the petroleum hydrocarbon extract increases,in which,according to the SARA analysis,the content of asphaltenes increases and the content of resins,aromatic and saturated hydrocarbons *** the composition of aroatic hydrocarbons,the proportion of a lkyltri methyl benzenes and dibenzothiophenes increases,phenanthrene homologues appear,and in the composition of saturated hydrocarbons,the amount of iso-structure alkanes decreases relative to the content of linear *** the temperature and pressure of the hydrothermal fluid to 380℃ and 20 MPa increases the degree of kerogen conversion from 12.4% to 23.6%.At the same time,changes occurring in the component composition of petroleum hydrocarbon extracts remains similar to the experiments carried out at 340℃ and 17 MPa;the content of naphthalenes decreases,the content of dibenzothiophenes increases and C11-C17,C19-C22alkyltrimethylbenzenes *** to IR spectroscopy,with increasing temperature and pressure of the hydrothermal fluid the intensity of the absorption bands of the aromatic ring,aliphatic fragments,and oxygen-containing groups increases in resins;the structural-group composition of asphaltenes changes little:aromaticity and the content of condensed

关键词： Carbonate deposits Organic matter Hydrothermal fluid Mobile hydrocarbons

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Understanding Discrepancy of Power System Dynamic Security Assessment with Unknown Faults: A Reliable Transfer Learning-based Method

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 427-431页

作者： Chao Ren Han Yu Yan Xu Zhao Yang Dong School of Computer Science and Engineering Nanyang Technological UniversitySingapore School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore

This letter proposes a reliable transfer learning(RTL)method for pre-fault dynamic security assessment(DSA)in power systems to improve DSA performance in the presence of potentially related unknown *** takes individual discrepancies into consideration and can handle unknown faults with incomplete *** experiment results demonstrate high DSA accuracy and computational efficiency of the proposed RTL *** analysis shows RTL can guarantee system performance.

关键词： Adversarial training dynamic security assessment maximum classifier discrepancy missing data transfer learning

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Visible Light Indoor Positioning System Based on Pisarenko Harmonic Decomposition and Neural Network

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Chinese Journal of Electronics 2024年第1期33卷 195-203页

作者： Li ZHAO Yi REN Qi WANG Lange DENG Feng ZHANG School of Electronic Information Engineering Xi’an Technological University

Visible-light indoor positioning is a new generation of positioning technology that can be integrated into smart lighting and optical communications. The current received signal strength(RSS)-based visible-light positioning systems struggle to overcome the interferences of background and indoor-reflected noise. Meanwhile, when ensuring the lighting, it is impossible to use the superposition of each light source to accurately distinguish light source information; furthermore, it is difficult to achieve accurate positioning in complex indoor environments. This study proposes an indoor positioning method based on a combination of power spectral density detection and a neural network. The system integrates the mechanism for visible-light radiation detection with RSS theory, to build a back propagation neural network model fitting for multiple reflection channels. Different frequency signals are loaded to different light sources at the beacon end, and the characteristic frequency and power vectors are obtained at the location end using the Pisarenko harmonic decomposition method. Then, a complete fingerprint database is established to train the neural network model and conduct location tests. Finally, the location effectiveness of the proposed algorithm is verified via actual positioning experiments. The simulation results show that, when four groups of sinusoidal waves with different frequencies are superimposed with white noise, the maximum frequency error is 0.104 Hz and the maximum power error is 0.0362 W. For the measured positioning stage, a 0.8 m × 0.8 m × 0.8 m solid wood stereoscopic positioning model is constructed, and the average error is 4.28 cm. This study provides an effective method for separating multi-source signal energies, overcoming background noise, and improving indoor visible-light positioning accuracies.

关键词： Neural networks Measurement uncertainty Position measurement Harmonic analysis Light emitting diodes Frequency estimation Indoor positioning systems

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Urea breath test for Helicobacter pylori infection in adult dyspeptic patients: A meta-analysis of diagnostic test accuracy

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World Journal of Gastroenterology 2024年第6期30卷 579-598页

作者： Fabian Fellipe Bueno Lemos Caroline Tianeze de Castro Marcel Silva Luz Gabriel Reis Rocha Gabriel Lima Correa Santos Luís Guilherme de Oliveira Silva Mariana Santos Calmon Cláudio Lima Souza Ana Carla Zarpelon-Schutz Kádima Nayara Teixeira Dulciene Maria de Magalhães Queiroz Fabrício Freire de Melo Instituto Multidisciplinar em Saúde Universidade Federal da BahiaVitória da Conquista 45029-094BahiaBrazil Instituto de Saúde Coletiva Universidade Federal da BahiaSalvador 40110040BahiaBrazil Campus Toledo Universidade Federal do ParanáToledo 85919-899ParanáBrazil Laboratory of Research in Bacteriology UFMGBelo Horizonte 30130-100Minas GeraisBrazil

BACKGROUND Helicobacter pylori(***)infection has been well-established as a significant risk factor for several gastrointestinal *** urea breath test(UBT)has emerged as a leading non-invasive method for detecting *** numerous studies confirming its substantial accuracy,the reliability of UBT results is often compromised by inherent *** findings underscore the need for a rigorous statistical synthesis to clarify and reconcile the diagnostic accuracy of the UBT for the diagnosis of *** *** To determine and compare the diagnostic accuracy of 13C-UBT and 14C-UBT for *** infection in adult patients with *** We conducted an independent search of the PubMed/MEDLINE,EMBASE,and Cochrane Central databases until April *** search included diagnostic accuracy studies that evaluated at least one of the index tests(^(13)C-UBT or ^(14)C-UBT)against a reference *** used the QUADAS-2 tool to assess the methodo-logical quality of the *** utilized the bivariate random-effects model to calculate sensitivity,specificity,positive and negative test likelihood ratios(LR+and LR-),as well as the diagnostic odds ratio(DOR),and their 95%confidence *** conducted subgroup analyses based on urea dosing,time after urea administration,and assessment *** investigate a possible threshold effect,we conducted Spearman correlation analysis,and we generated summary receiver operating characteristic(SROC)curves to assess ***,we visually inspected a funnel plot and used Egger’s test to evaluate publication *** both as reliable diagnostic tools in clinical *** In summary,our study has demonstrated that ^(13)C-UBT has been found to outperform the ^(14)C-UBT,making it the preferred diagnostic ***,our results emphasize the significance of carefully considering urea dosage,assessment timing,and measurement techniques for both tests to enh

关键词： Helicobacter pylori Urea breath test Diagnosis Diagnostic test accuracy Meta-analysis

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Is magnesium deficiency the major cause of needle chlorosis of Pinus taeda in Brazil?

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Journal of Forestry Research 2024年第2期35卷 209-221页

作者： Antônio Carlos Vargas Motta Shizuo Maeda Valdécio dos Santos dos Santos Rodrigues Tamires Maiara Ercole Stephen Arthur Prior Ana Elisa Lyra Brumat Amanda Pacheco Cardoso Moura Julierme Zimmer Barbosa João Bosco Vasconcellos Gomes Department of Soil Sciences and Agriculture Engineering Federal University of ParanáR.dos Funcionários1540.CuritibaParanáCEP 80035‑050Brazil Brazilian Agricultural Research Company Embrapa FlorestasEstr.da Ribeira–Br‑476Km 111–Parque Monte Castelo.ColomboParanáCEP 83411‑000Brazil United States Department of Agriculture‑Agricultural Research Service USDA-ARS National Soil Dynamics Laboratory411 South Donahue DriveAuburnAL 36832USA Reforestation Remasa Rodovia PR 170–Km 522.BiturunaParanáCEP 84640‑000Brazil federal Institute of Southeast of Minas Gerais R.Luz Interior360.Juiz de ForaMinas Gerais CEP 36030‑713Brazil

Needle chlorosis(NC)in Pinus taeda *** in Brazil becomes more frequent after second and third harvest rotation *** a study to identify factors contributing to yellowing needle chorosis(YNC),trees were grown in soils originating from contrasting parent materials,and soils and needles(whole,green and chlorotic portions)from 1-and 2-year-old branches and the first and second needle flush release at four sites with YNC on *** were analyzed for various elements and *** soils had very low base levels(Ca^(2+),Mg^(2+)and K^(+))and P,suggesting a possible lack of multiple *** symptoms started at needle tips,then extended toward the needle base with *** flush needles had longer portions with YNC than second flush needles *** from the lower crown also had more symptoms along their length than those higher in the *** were similar to those reported for *** chlorotic portions,Mg and Ca concentrations were well below critical values;in particular,Mg levels were only one third of the critical value of 0.3 g kg^(-1).Collectively,results suggest that Mg deficiency is the primary reason for NC of *** in various parent soils in Brazil.

关键词： Nutritional deficiency Forest management Soil depletion Pine foliar analysis Needle chlorosis

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Tuning heterogeneous microstructures to enhance mechanical properties of nano-TiN particle reinforced Haynes 230 composites by laser powder bed fusion

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Rare Metals 2024年第9期43卷 4548-4565页

作者： Wen-Jie Liu Hui Li Qian-Xing Yin He-Jun Du School of Power and Mechanical Engineering Wuhan University The Institute of technological Sciences Wuhan University School of Mechanical&Aerospace Engineering Nanyang Technological University

Laser powder bed fusion(LPBF) is considered to be one of the most promising additive manufacturing technologies for producing components with geometries and high geometrical precision that are unattainable by traditional technologies. The superalloy exhibits exceptional mechanical and high-temperature performances,rendering it a prime candidate for advanced aero-engine applications. Despite the high demand for LPBF-manufactured superalloys, the superalloy is one of the materials manufactured difficultly by LPBF due to their large laser absorptivity fluctuation, poor molten pool stability and sharp temperature gradient. Hence, superalloys are characterized by severe pores, undesirable coarse columnar grains and poor mechanical properties. In this work, the effect of nano-Ti N particles on defects, molten pool characteristics and microstructure and performance of the composites were investigated. The 4.5 wt% Ti N/Haynes230 samples exhibited exceptional nanohardness and elastic modulus with maximum values reaching 5.53 GPa and 240.03 GPa, respectively. These superior mechanical properties were attributed to the combined effects of spatter and gas pore inhibition, grain refinement and duplex nanophases strengthening. Moreover, the stability of molten pool was enhanced, and spatter was effectively suppressed by adding nano-Ti N particles, while grain refinement and columnar to equiaxed transitions were promoted. Furthermore, the matrix exhibited a high dislocation density due to a significant hindrance of dislocation movement caused by massive nano-phases(e.g., Ti N and M23C6), resulting in the formation of extensive dislocation tangles and *** work offers novel insights into the role of nanoparticles reinforced superalloy composites by LPBF.

关键词： Composites Laser powder bed fusion Mechanical properties Microstructure Molten pool characteristics

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Distributed Fault-Tolerant Control of Uncertain Multi-Agent Systems with Connectivity Maintenance

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Journal of Systems Science & Complexity 2024年第1期37卷 40-62页

作者： XING Xueyan HU Guoqiang Continental-NTU Corporate Lab Nanyang Technological UniversitySingapore 639798Singapore Continental-NTU Corporate Lab and the School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore 639798Singapore

In this paper,a distributed cooperative control protocol is presented to deal with actuator failures of multi-agent systems in the presence of connectivity *** the developed strategy,each agent can track the reference trajectory of the leader in the presence of actuator failures,disturbances and *** connectivity of the multi-agent system can always be ensured during the control *** achieve the aforementioned control objectives,a potential function is introduced to the distributed adaptive fault-tolerant control algorithm to preserve the initial connected network among the *** uncertainty of the multi-agent system,which is allowed to be described by discontinuous functions,is approximated and compensated using the fuzzy logic *** asymptotic stability of the closed-loop system is demonstrated through the use of Cellina’s approximate selection theorem of nonsmooth *** to the developed adaptive laws,the upper bound of the disturbance is allowed to be uncertain,which facilitates the implementation of the control ***,simulation results are provided to verify the effectiveness of the proposed control scheme.

关键词： Actuator failure connectivity maintenance coordination control uncertainties

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A Cocktail of Natural Compounds Holds Promise for New Immunotherapeutic Potential in Head and Neck Cancer

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Chinese Journal of Integrative Medicine 2024年第1期30卷 42-51页

作者： Sunil Kumar Asmita Das Department of Biotechnology Delhi Technological UniversityDelhi(110042)India

Objective: To obtain detailed understanding on the gene regulation of natural compounds in altering prognosis of head and neck squamous cell carcinomas(HNSC). Methods: Gene expression data of HNSC samples and peripheral blood mononuclear cells(PBMCs) of HNSC patients were collected from Gene Expression Omnibus(GEO). Differential gene expression analysis of GEO datasets were achieved by the GEO2R tool. Common differentially expressed gerres(DEGs) were screened by comparing DEGs of HNSC with those of PBMCs. The combination was further analyzed for regulating pathways and biological processes that were affected. Results: Totally 110 DEGs were retrieved and identified to be involved in biological processes related to tumor regulation. Then 102 natural compounds were screened for a combination such that the expressions of all 110 commonly DEGs were altered. A combination of salidroside, ginsenoside Rd, oridonin, britanin, and scutellarein was chosen. A multifaceted, multi-dimensional tumor regression was showed by altering autophagy, apoptosis, inhibiting cell proliferation, angiogenesis, metastasis and inflammatory cytokines production. Conclusions: This study has helped develop a unique combination of natural compounds that will markedly reduce the propensity of development of drug resistance in tumors and immune evasion by tumors. The result is crucial to developing a combinatorial natural therapeutic cocktail with accentuated immunotherapeutic potential.

关键词： natural compounds chemopreventive gene expression head and neck cancer immunomodulator salidroside ginsenoside Rd oridonin britanin scutellarein

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Optimal Coordination of Transportable Power Sources and Repair Crews for Service Restoration of Distribution Networks Considering Uncertainty of Traffic Congestion

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 189-201页

作者： Zhao Shi Yan Xu Dunjian Xie Shiwei Xie Amer M.Y.M.Ghias Nanyang technological university Singapore the School of Electrical Engineering and Automation Fuzhou UniversityFuzhou 350108China

This paper proposes a new method for service restoration of distribution network with the support of transportable power sources(TPSs)and repair crews(RCs).Firstly,a coupling model of distribution networks and vehicle routing of TPSs and RCs is proposed,where the TPSs serve as emergency power supply sources,and the RCs are used to repair the faulted *** the uncertainty of traffic congestion,the probability distribution of the travel time spent on each road is derived based on the Nesterov user equilibrium model,and a two-stage stochastic program is formulated to determine the optimal routings of TPSs and *** efficiently solve the proposed stochastic mixed-integer linear program(MILP),a two-phase scenario reduction method is then developed to scale down the problem size,and an adaptive progressive hedging algorithm is used for an efficient *** effectiveness of the proposed methods and algorithms has been illustrated in a modified IEEE 33-bus system.

关键词： Service restoration distribution network traffic uncertainty transportable power source repair crew stochastic program

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