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An Efficient Method to Estimate Admittance of Black-boxed Inverter-based Resources for Varying Operating Points

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 421-426页

作者： Weihua Zhou Bin Liu Nabil Mohammed Behrooz Bahrani Department of Electrical and Computer Systems Engineering Monash UniversityMelbourne 3800Australia Energy Centre Commonwealth Scientific and Industrial Research Organisation(CSIRO)Newcastle 2300Australia.He is now with the Network Planning DivisionTransgridSydney 2000Australia

Traditional analytical approaches for stability assessment of inverter-based resources(IBRs),often requiring detailed knowledge of IBR internals,become impractical due to IBRs’proprietary *** measurements,relying on electromagnetic transient simulation or laboratory settings,are not only time-intensive but also operationally inflexible,since various non-linear control loops make IBRs’admittance models operating-point ***,such admittance measurements must be performed repeatedly when operating point *** avoid time-consuming and cumbersome measurements,admittance estimation for arbitrary operating points is highly ***,existing admittance estimation algorithms usually face challenges in versatility,data demands,and *** this challenge,this letter presents a simple and efficient admittance estimation method for blackboxed IBRs,by utilizing a minimal set of seven operating points to solve a homogeneous linear equation *** studies demonstrate this proposed method ensures high accuracy across various types of *** accuracy is satisfying even when non-negligible measurement errors exist.

关键词： Admittance estimation black box inverterbased resource measurement error operating point

Improved LS+MAR hybrid method to UT1-UTC ultra-short-term prediction by using first-order-difference UT1-UTC

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geodesy and Geodynamics 2024年第4期15卷 379-385页

作者： Fei Ye Yunbin Yuan BeiDou High-precision Satellite Navigation and Location Service Hunan Engineering research Center Hunan Institute of Geomatics Sciences and TechnologyChangsha410007China State Key Laboratory of geodesy and Earth's Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan430077China HNCORS Data Center Hunan Institute of Geomatics Sciences and TechnologyChangsha 410007China

Accurate ultra-short-term prediction of the Earth rotation parameters(ERP)holds paramount impor-tance for real-time applications,particularly in reference frame *** them,diurnal rota-tion(UT1-UTC)which cannot be directly estimated through Global Navigation Satellite System(GNSS)techniques,significantly affects the rapid and ultra-rapid orbit determination of GNsS ***-ently,the traditional LS(least squares)+AR(autoregressive)and LS+MAR(multivariate autoregressive)hybrid methods stand as primary approaches for UT1-UTC ultra-short-term predictions(1-10 days).The LS+MAR hybrid method relies on the UT1-UTC and LOD(length of day)***,the correlation between LOD and first-order-difference UT1-UTC is stronger than that between LOD and *** light of this,and with the aid of the first-order-difference UT1-UTC,we propose an enhanced LS+MAR hybrid method to UT1-UTC ultra-short-term *** using the UT1-UTC and LOD data series of the IERS(International Earth Rotation and Reference Systems Service)EOP 14 C04 product,we conducted a thorough analysis and evaluation of the improved method's prediction performance compared to the traditional LS+AR and LS+MAR hybrid *** to the numerical results over more than 210 days,they demonstrate that,when considering the correlation information between the LoD and the first-order-difference UT1-UTC,the mean absolute errors(MAEs)of the improved LS+MAR hybrid method range from 21 to 934μs in 1-10 days *** comparison to the traditional LS+AR hybrid method,the MAEs show a reduction of 7-53μs in 1-10 days predictions,with corresponding improvement percentages ranging from 1 to 28%.Similarly,when compared to the traditional LS+MAR hybrid method,the MAEs have a reduction of 5-42μs in 1-10 days predictions,with corresponding improvement percentages ranging from 4-20%.Additionally,when aided by GNSS-derived LOD data series,the MAEs of improved LS+MAR hybrid method experience further

关键词： UT1-UTCultra-short-termprediction Rapidandultra-rapidproducts LS+AR and LS+MAR Correlation First-order-differenceUT1-UTC

Characteristics and genesis of shoal facies reservoir of the Lower Ordovician Tongzi Formation in southeastern Sichuan Basin,China

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Petroleum 2024年第3期10卷 427-439页

作者： Ruiqing Tao Hao Tang Wei Yan Yading Li Qianwen Mo Ling Li Li Zhou Tao Ma Jinbiao An Guoliang Xiao Xiucheng Tan Southwest Petroleum University Division of Key Laboratory of Carbonate ReservoirsCNPCChengdu610500China research Institute of Exploration and Development PetroChina Southwest Oil and Gas Field CompanyChengdu610051China Exploration division PetroChina Southwest Oil and Gas Field CompanyChengdu610051China College of Geosciences China University of Petroleum(Beijing)Beijing102200China Chuanzhong Oil and Gas Geological research Institute PetroChina Southwest Oil and Gas Field CompanySuining629000China

The Lower Ordovician Tongzi Formation containing abundant shoal sediments is the most promising stratum for the petroleum exploration in the Sichuan ***,the current studies mainly focus on the central part of the Basin,the systematic analysis of the southeastern part with well-developed shoal facies is *** paper aims to clarify the characteristics and genesis of the Tongzi Formation reservoir in Southeastern Sichuan Basin,following an analysis of sedimentary facies within the sequence stratigraphic *** research shows that the main types of reservoir rocks are oolitic,intraclastic and bioclastic *** the reservoir spaces consist mainly of intergranular(dissolved)pores,intercrystalline(dissolved)pores,intragranular dissolved pores and *** them,intergranular pores account for the highest proportion,which is followed by intragranular dissolved *** addition,most throats are necking and flaky which mainly connect intergranular and intercrystalline pores,*** diagenetic sequence shows that penecontemporaneous karst well improved the porosity of the reservoir in the early-stage although the cementation and compaction reduced parts of *** reservoir formation is associated with the tectonic-depositional settings,diageneses and terrigenous *** and submerged uplifts,forming in the early Ordovician amalgamation between Yangtze and Cathaysia blocks,accumulated shoal sediments as the material basis for the reservoir *** karst forming intragranular dissolved pores and the dolomitization aiding grainstones to resist the pressure solution are the key to increasing porosity and preserving *** absence of terrigenous contamination prevented intergranular pores from being strongly cemented,which resulted in the reservoir difference between the central and southeastern Sichuan *** study can be used as a reference for the further exploration of Ordovician

关键词： Reservoir characteristics Reservoir genesis Tongzi formation Lower ordovician Southeastern Sichuan Basin

Development and validation of a novel non-invasive test for diagnosing nonalcoholic fatty liver disease in Chinese children

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World Journal of Pediatrics 2024年第4期20卷 413-421页

作者： Zhe-Wen Qin Qian-Nan Ren Hong-Xi Zhang Ya-Ru Liu Ke Huang Wei Wu Guan-Ping Dong Yan Ni Jun-Fen Fu division of Endocrinology National Clinical Research Center for Child HealthNational Children’s Regional Medical CenterThe Children’s HospitalDepartment of EndocrinologyNational Clinical Research Center for Child HealthNational Children’s Regional Medical CenterThe Children’s HospitalZhejiang University School of MedicineHangzhou310052China

With the exploding prevalence of obesity,many children are at risk of developing nonalcoholic fatty liver *** anthropometric and laboratory parameters,our study aimed to develop a model to quantitatively evaluate liver fat content(LFC)in children with *** A well-characterized cohort of 181 children between 5 and 16 years of age were recruited to the study in the Endocrinology Department as the derivation *** external validation cohort comprised 77 *** assessment of liver fat content was performed using proton magnetic resonance *** and laboratory metrics were measured in all subjects.B-ultrasound examination was carried out in the external validation *** Kruskal-Wallis test,Spearman bivariate correlation analyses,univariable linear regressions and multivariable linear regression were used to build the optimal predictive *** The model was based on indicators including alanine aminotransferase,homeostasis model assessment of insulin resistance,triglycerides,waist circumference and Tanner *** adjusted R^(2)of the model was 0.589,which presented high sensitivity and specificity both in internal[sensitivity of 0.824,specificity of 0.900,area under curve(AUC)of 0.900 with a 95%confidence interval:0.783–1.000]and external validation(sensitivity of 0.918 and specificity of 0.821,AUC of 0.901 with a 95%confidence interval:0.818–0.984).Conclusions Our model based on five clinical indicators was simple,non-invasive,and inexpensive;it had high sensitivity and specificity in predicting LFC in ***,it may be useful for identifying children with obesity who are at risk for developing nonalcoholic fatty liver disease.

关键词： Biochemical markers Children Magnetic resonance spectroscopy Nonalcoholic fatty liver disease Pediatric obesity

Disclosing the true impact of screening endoscopy in colorectal cancer prevention

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Cancer Communications 2024年第4期44卷 504-507页

作者： Thomas Heisser Carlo Senore Michael Hoffmeister Lina Jansen Hermann Brenner division of Clinical Epidemiology and Aging research German Cancer Research Center(DKFZ)HeidelbergBaden-WürttembergGermany Epidemiology and Screening Unit Reference Centre for Epidemiology and Cancer PreventionUniversity Hospital Cittàdella Salute e della ScienzaTurinPiedmontItaly Epidemiological Cancer Registry Baden-Württemberg German Cancer Research Center(DKFZ)HeidelbergBaden-WürttembergGermany division of Preventive Oncology German Cancer Research Center(DKFZ)and National Center for Tumor Diseases(NCT)HeidelbergBaden-WürttembergGermany German Cancer Consortium(DKTK) German Cancer Research Center(DKFZ)HeidelbergBaden-WürttembergGermany

Preprint:https://***/10.1101/*** trials,cohort and modeling studies have consistently demonstrated a major impact of screening endoscopies on reducing colorectal cancer(CRC)inci-dence and mortality[1].Over time,CRC mortality starts to be lower in those who underwent screening compared to those who did not due to earlier detection of prevalent.

关键词： prevention endoscopy impact CRC

Importance of dietary supplementation of soluble and insoluble fibers to sows subjected to high ambient temperatures during late gestation and effects on lactation performance

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Animal Nutrition 2024年第1期16卷 73-83页

作者： Seung Min Oh Abdolreza Hosseindoust Sang Hun Ha Jun Young Mun Joseph Moturi Habeeb Tajudeen Yo Han Choi Su Hyup Lee Jin Soo Kim Gyeongbuk Livestock research Institute Department of Animal Industry Convergence Kangwon National University Swine division National Institute of Animal Science Rural Development Administration Department of Swine Science Korea National University of Agriculture and Fisheries

Heat stress adversely affects sows' performance, which can be improved by applying proper nutritional strategies. This study was conducted to investigate the interactive effects of dietary fiber levels and sources on sows' reproductive performance, metabolic response during gestation, and the carry-over influence on litter performance in the lactation period during heat stress(average room temperature of 27.1°C). Fifty-four multiparous sows(Landrace × Yorkshire; initial body weight of 236.3 ± 16 kg; 2, 3and 4 parities) at d 90 of gestation were assigned to a 2 × 3 factorial arrangement(9 sows/treatment),involving 2 dietary fiber levels(4.5% and 6% crude fiber) and 3 dietary fiber sources(wheat bran [WB],palm kernel meal [PK], and beet pulp [BP]). Sows fed the BP diet had highest(P < 0.01) feed intake and constipation index and lowest(P < 0.01) farrowing duration. Piglet weight(P = 0.041) and litter weight(P < 0.01) at weaning were higher in sows in the BP treatment compared to PK treatment. Sows in the BP treatment showed the greatest(P < 0.01) digestibility of crude protein and neutral detergent fiber. The fecal concentration of acetate was the lowest(P < 0.01) in the PK treatment. Total short-chain fatty acid production was increased in the WB and BP treatments compared with the PK. Sows in the BP treatment showed the lowest(P = 0.036) hair cortisol. The blood insulin concentration of sows was higher(P = 0.026) in the high fiber(6%) treatment compared with the low fiber(4.5%) treatment at 90 min and120 min after the meal. The concentration of phthalic acid, succinic acid, phenylethylamine, hydrocinnamic acid, iron, linoleic acid, glycerol, ketone, and formamide were increased(P < 0.05) in the BP treatment compared with the WB. The BP treatment with high soluble fiber content improved the constipation index, farrowing duration, and litter performance, while high insoluble fibers increased sows comfort and reduced stress factors including respiratory rate and rectal

关键词： Soluble fiber Insoluble fiber Beet pulp Wheat bran Palm kernel Metabolites

Second-order error analysis of the averaged L1 scheme L1 for time-fractional initial-value and subdiffusion problems

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Science China Mathematics 2024年第7期67卷 1641-1664页

作者： Jinye Shen Fanhai Zeng Martin Stynes School of Mathematics Southwestern University of Finance and EconomicsChengdu611130China School of Mathematics Shandong UniversityJinan250100China Applied and Computational Mathematics division Beijing Computational Science Research CenterBeijing100193China

Fractional initial-value problems(IVPs) and time-fractional initial-boundary value problems(IBVPs), each with a Caputo temporal derivative of order α ∈(0, 1), are considered. An averaged variant of the well-known L1 scheme is proved to be O(N^(-2)) convergent for IVPs on suitably graded meshes with N points, thereby improving the O(N^(-(2-α))) convergence rate of the standard L1 scheme. The analysis relies on a delicate decomposition of the temporal truncation error that yields a sharp dependence of the order of convergence on the degree of mesh grading used. This averaged L1 scheme can be combined with a finite difference or piecewise linear finite element discretization in space for IBVPs, and under a restriction on the temporal mesh width, one gets again O(N^(-2)) convergence in time, together with O(h^(2)) convergence in space,where h is the spatial mesh width. Numerical experiments support our results.

关键词： time-fractional subdiffusion averaged L1 scheme

An improved positioning model of deep-seafloor datum point at large incidence angle

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Journal of Oceanology and Limnology 2024年第1期42卷 90-100页

作者： Qianqian LI Shoulian CAO Fanlin YANG Yu LUO Qian TONG College of Underwater Acoustic Engineering Harbin Engineering UniversityHarbin 150000China College of geodesy and Geomatics Shandong University of Science and TechnologyQingdao 266590China Key Laboratory of Ocean Geomatics Ministry of Natural ResourcesQingdao 266590China

The inhomogeneous sound speed in seawater causes refraction of sound waves,and the elimination of the refraction effect is essential to the accuracy of underwater acoustic *** raytracing method is an indispensable tool for effectively handling ***,this method has a conflict between localization accuracy and computational *** equivalent sound speed profile(ESSP)method uses a simple sound speed profile(SSP)instead of the actual complex SSP,which can improve positioning precision but with residual *** residual error is especially non-negligible in deep water and at large beam incidence *** analyzing the residual error of the ESSP method through a simulation,an empirical formula of error is *** data collected in the sailing circle mode(large incidence angle)of the South China Sea are used for *** experiments show that compared to the ESSP method,the improved algorithm has higher positioning precision and is more efficient than the ray-tracing method.

关键词： underwater acoustic positioning seafloor datum points large incident angle equivalent sound speed profile(ESSP) deep water

Quantifying droplet–solid friction using an atomic force microscope

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Droplet 2024年第2期3卷 105-112页

作者： Xue Qi Koh Calvin Thenarianto Ville Jokinen Dan Daniel Institute of Materials research and Engineering(IMRE) Agency for ScienceTechnology and Research(A*STAR)SingaporeSingapore Department of Chemistry and Materials Science School of Chemical EngineeringAalto UniversityEspooFinland division of Physical Sciences and Engineering King Abdullah University of Science and Technology(KAUST)ThuwalSaudi Arabia

Controlling the wetting and spreading of microdroplets is key to technologies such as microfluidics,ink-jet printing,and surface *** angle goniometry is commonly used to characterize surface wetting by droplets,but the technique is ill-suited for high contact angles close to 180°.Here,we attach a micrometric-sized droplet to an atomic force microscope cantilever to directly quantify droplet–solid friction on different surfaces(superhydrophobic and underwater superoleophobic)with sub-nanonewton force *** demonstrate the versatility of our approach by performing friction measurements using different liquids(water and oil droplets)and under different ambient environments(in air and underwater).Finally,we show that underwater superoleophobic surfaces can be qualitatively different from superhydrophobic surfaces:droplet–solid friction is highly sensitive to droplet speeds for the former but not for the latter surface.

关键词： surface. underwater latter