检索结果-南通市图书馆

Observation 20-s periodic signals on Mars from InSight,Sols 800-1,000

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2023年第2期7卷 193-215页

作者： HuiXing bi DaoYuan Sun MingWei Dai Deep Space Exploration Laboratory/School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Laboratory of Seismology and Physics of Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Comparative Planetology ChinaHefei 230026China

Seismometers of the InSight probe(Interior Exploration using Seismic Investigation,Geodesy and Heat Transport)currently operating on Mars have recorded not only seismic events but also high-frequency non-seismic periodic signals that appear to have been induced by variations in the Martian environment and the ***,we report an observation of a long-period signal with a dominant period of~20 s from Martian solar days(Sol)800 to Sol 1,*** 20-s signal is detected mostly at quiet nighttime—from22:00 to 04:00 LMST(Local Mean Solar Time)—at the InSight landing *** measurement of the particle motion suggests that this linearly polarized signal focuses on the horizontal plane with an angle of~30°from the *** examining the temporal variation of the signal’s amplitude and polarization angle and its times of occurrence in relation to the planet’s atmospheric data,we suggest that this20-s signal may be relevant to wind and temperature variations on ***,we study the possible influence of this 20-s signal on the noise autocorrelation and find that the stacked autocorrelograms can be quite different when the 20-s signal is present.

关键词： Mars periodic signal particle motion autocorrelation

Diesel Engine Valve Clearance Fault Diagnosis based on Features Extraction Techniques and FastICA-SVM

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2017年第4期30卷 991-1007页

作者： Ya-bing Jing Chang-Wen Liu Feng-Rong bi Xiao-Yang bi Xia Wang Kang Shao State Key Laboratory of Engines Tianjin UniversityTianjin 300072 China School of Mechanical Engineering Tianjin UniversityTianjin 300072 China Internal Combustion Engine Research Institute Tianjin University Tianjin 300072 China

Numerous vibration-based techniques are rarely used in diesel engines fault diagnosis in a direct way, due to the surface vibration signals of diesel engines with the complex non-stationary and nonlinear time-varying fea- tures. To investigate the fault diagnosis of diesel engines, fractal correlation dimension, wavelet energy and entropy as features reflecting the diesel engine fault fractal and energy characteristics are extracted from the decomposed signals through analyzing vibration acceleration signals derived from the cylinder head in seven different states of valve train. An intelligent fault detector FastICA-SVM is applied for diesel engine fault diagnosis and classification. The results demonstrate that FastlCA-SVM achieves higher classification accuracy and makes better general- ization performance in small samples recognition. besides, the fractal correlation dimension and wavelet energy and entropy as the special features of diesel engine vibration signal are considered as input vectors of classifier FastlCA- SVM and could produce the excellent classification results. The proposed methodology improves the accuracy of fea- ture extraction and the fault diagnosis of diesel engines.

关键词： Feature extraction Diesel engine valve train FastlCA PCA Support vector machine

Characterizing prediction errors of a new tree height model for cut-to-length Pinus radiata stems through the burr TypeⅫdistribution

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2023年第6期34卷 1899-1914页

作者： Xinyu Cao Huiquan bi Duncan Watt Yun Li School of Information Science and Technology Beijing Forestry UniversityBeijing 100083People’s Republic of China Forest Science NSW Department of Primary IndustriesLevel 304PSQParramattaNSW 2150Australia School of Ecosystem and Forest Sciences Faculty of ScienceThe University of MelbourneWater StreetCreswickVIC 3363Australia Snowy Region Forestry Corporation of NSW76 Capper StreetTumutNSW 2720Australia

Unlike height-diameter equations for standing trees commonly used in forest resources modelling,tree height models for cut-to-length(CTL)stems tend to produce prediction errors whose distributions are not conditionally normal but are rather leptokurtic and *** feature was merely noticed in previous studies but never thoroughly *** study characterized the prediction error distribution of a newly developed such tree height model for Pin us radiata(***)through the three-parameter burr TypeⅫ(bⅫ)*** model’s prediction errors(ε)exhibited heteroskedasticity conditional mainly on the small end relative diameter of the top log and also on DbH to a minor *** serial correlations were also present in the data.A total of 14 candidate weighting functions were compared to select the best two for weightingεin order to reduce its conditional *** weighted prediction errors(εw)were shifted by a constant to the positive range supported by the bXII *** the distribution of weighted and shifted prediction errors(εw+)was characterized by the bⅫdistribution using maximum likelihood estimation through 1000 times of repeated random sampling,fitting and goodness-of-fit testing,each time by randomly taking only one observation from each tree to circumvent the potential adverse impact of serial correlation in the data on parameter estimation and *** nonparametric two sample Kolmogorov-Smirnov(KS)goodness-of-fit test and its closely related Kuiper’s(KU)test showed the fitted bⅫdistributions provided a good fit to the highly leptokurtic and heavy-tailed distribution ofε.Random samples generated from the fitted bⅫdistributions ofεw+derived from using the best two weighting functions,when back-shifted and unweighted,exhibited distributions that were,in about97 and 95%of the 1000 cases respectively,not statistically different from the distribution ofε.Our results for cut-tolength *** stems repre

关键词： Conditional heteroskedasticity Leptokurtic error distribution Skedactic function Nonlinear quantile regression Weighted prediction errors Serial correlation Random sampling and fitting Nonparametric goodnessof-fit tests

Microstructure and mechanical behavior of laser aided additive manufactured low carbon interstitial Fe_(49.5)Mn_(30)Co_(10)Cr_(10)C_(0.5)multicomponent alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第18期77卷 38-46页

作者： Y.Chew Z.G.Zhu F.Weng S.b.Gao F.L.Ng b.Y Lee G.J.bi Singapore Institute of Manufacturing Technology 73 Nanyang Drive637662Singapore School of Mechanical Aerospace Engineering Nanyang Technological University50 N any ang Avenue639798Singapore

Laser aided additive manufacturing(LAAM)was used to fabricate bulk Fe_(49.5)Mn_(30)Co_(10)Cr_(10)C_(0.5)interstitial multicomponent alloy using pre-alloyed *** room temperature yield strength(σ_y),ultimate tensile strength(σ_(UTS))and elongation(ε_(UTS))were 645 MPa,917 MPa and 27.0%*** asbuilt sample consisted of equiaxed and dendritic cellular structures formed by elemental *** cellular structures together with oxide particle inclusions were deemed to strengthen the *** other contributing components include dislocation strengthening,friction stress and grain boundary *** highε_(UTS)was attributed to dislocation motion and activation of both twinning and transformation-induced plasticity(TWIP and TRIP).Tensile tests performed at-40℃and-130℃demonstrated superior tensile strength of 1041 MPa and 1267 MPa ***,almost no twinning was observed in the fractured sample tested at-40℃and-130℃.Instead,higher fraction of strain-induced hexagonal close-packed(HCP)εphase transformation of 21.2%were observed for fractured sample tested at-40℃,compared with 6.3%in fractured room temperature sample.

关键词： Multicomponent alloys Laser aided additive manufacturing Additive manufacturing Microstructure Mechanical property

Enhanced electromagnetic-interference shielding effectiveness and mechanical strength of Co-Ni coated aramid-carbon blended fabric

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2021年第10期34卷 103-114页

作者： Qin WANG Yumeng XU Siyi bi Yinxiang LU Department of Materials Science Fucian UniversityShanghai 200433China

An efficient method was proposed to prepare high-performance conductive AramidCarbon blend Fabrics(ACbF)with cobalt-nickel(Co-Ni)alloy coatings,which is conducive to industrial *** grid-like substrate composed of aramid and carbon fibers was innovatively used in flexible Electromagnetic Interference(EMI)shielding *** natural network structure is advantageous to the uniform deposition of metal particles to the establishment of conductive pathways subsequently in order to improve *** induction of a synergistic effect from Electromagnetic(EM)wave-reflection and EM wave-absorption through the whole carbonCo-Ni-ternary system notably enhanced the EMI Shielding Effectiveness(SE)value to an average of 42.57 d b in the range of 30-6000 *** the other hand,together with the inherent toughness of the alloy coatings,the tensile strength of the aramid fibers used for bulletproof made a significant contribution to the desired mechanical *** light weight of the resultant composite made it applicable to aerospace vehicles simultaneously.X-ray Photoelectron Spectroscopy(XPS)was conducted to investigate the variations of elements and groups on the sample surface in pretreating *** elemental components and surface morphologies of fabric samples during different stages of the process were investigated by Scanning Electron Microscope(SEM)and Energy Dispersive spectrometer(EDX)measurements.X-Ray Diffraction(XRD)results indicated that the obtained Co-Ni alloy coating had a combined Hexagonal Closed-Packed(HCP)and FacedCentered Cubic(FCC)crystalline *** relatively high corrosion resistance demonstrated in different acid and alkaline conditions was instrumental in more complex environments as well.

关键词： Aramid fibers Carbon fibers Cobalt-nickel(Co-Ni)Coating Electroless plating Electromagnetic shielding

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant biology 2012年第5期54卷 300-311页

作者： Xufeng bai bi Wu Yongzhong Xing National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research Huazhong Agricultural University Wuhan 430070 China

Grain yield is one of the most important indexes in rice breeding, which is governed by quantitative trait loci （QTLs）. Different map- ping populations have been used to explore the QTLs controlling yield related traits. Primary populations such as F2 and recombi- nant inbred line populations have been widely used to discover QTLs in rice genome-wide, with hundreds of yield-related QTLs detected. Advanced populations such as near isogenic lines （NILs） are efficient to further fine-map and clone target QTLs. NILs for primarily identified QTLs have been proposed and confirmed to be the ideal population for map-based cloning. To date, 20 QTLs directly affecting rice grain yield and its components have been cloned with NIL-F2 populations, and 14 new grain yield QTLs havebeen validated in the NILs. The molecular mechanisms＇of＇a continuous/y increasing number of genes are being unveiled, which aids in the understanding of the formation of grain yield. Favorable alleles for rice breeding have been ＇mined＇ from natural cultivars and wild rice by association analysis of known functional genes with target trait performance. Reasonable combination of favorable alleles has the potential to increase grain yield via use of functional marker assisted selection.

关键词： Grain yield mapping population near isogenic lines (NILs) favorable alleles functional markers,

The single neutral top-higgs production at LHC and ILC in the Topcolor-Assisted Technicolor Model

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2013年第5期56卷 933-940页

作者： LIU Yaobei bi YanPing LI YuQi Henan Institute of Science and Technology Department of Life Science and Technique Xinxiang Medical University

In this paper, we study the single neutral top-higgs （h0） production processes at the CERN Large Hadron Collider （LHC） and the International Linear Collider （ILC）. At the LHC, the production rates of processes pp →Z（W）h0 are too small to detect ht0. However, with the reasonable parameter values, the cross sections can reach the level of 102 fb for qq→qqh0process and 103 fb for top quark associated production process pp → th0 ＋ X, respectively. At the ILC, we study the single top-higgs production processes e-y → veW-h0 and yy → W＋W-h0 in e-y and yy collisions. It is found that the production cross sections can reach the level of a few t-b with reasonable parameter values. Furthermore, such processes with the flavor-changing decay mode h0 tO might provide typical signatures to detected the top-higgs. Therefore, it is hopeful to find the signal of top-higgs at the LHC and ILC experiments via theses processes and test the TC2 model directly.

关键词： topcolor-assisted technicolor model top-higgs LHC ILC

Tripartite motif-containing protein 11(TRIM11):a novel weapon against Alzheimer’s disease

在线全文

学校读者我要写书评

暂无评论

Signal Transduction and Targeted Therapy 2024年第2期9卷 339-340页

作者： Yichu Fu bi Zhang Jianfeng Liu College of Life Science and Technology Key Laboratory of Molecular Biophysics of MOEHuazhong University of Science and TechnologyWuhanHubei 430074China

In a recent study published in Science,Zhang et *** that tripartite motif-containing(TRIM)protein 11(TRIM11)exhibited strong inhibition on tau aggregation,which is a pathological characteristic of tauopathies including Alzheimer’s disease(AD).1 This makes TRIM11 a promising novel target for the treatment of AD and other tauopathies.

关键词： Alzheimer tau TRIM

Remote Intelligent Identification System of Structural Damage

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2004年第5期9卷 812-816页

作者： RAOWen-bi ZHANGXiang bostromHenrik SchoolofComputerScienceandTechnology WuhanUniversityofTechnologyWuhan430070.HubeiChina DepartmentofComputerandElectronic HubeiUniversityofEconomicWuhan430070Hubei.China DepartmentofComputerandSystemsSciences StockholmUniversity／KTH.SE-16440.Sweden

The focus of this paper is to build the damage identify system, which performs “system identification” to detect the positions and extens of structural damages. The identification of structural damage can be characterized as a nonlinear process which linear prediction models such as linear regression are not suitable. However, neural network techniques may provide an effective tool for system identification. The method of damage identification using the radial basis function neural network (RbFNN) is presented in this paper. Using this method, a simple reinforced concrete structure has been tested both in the absence and presence of noise. The results show that the RbFNN identification technology can be used with related success for the solution of dynamic damage identification problems, even in the presence of a noisy identify data. Furthermore, a remote identification system based on that is set up with Java Technologies. Key words RbFNN - inteligent identification - structural damage - brower/Server (b/S) model CLC number TP 183 Foundation item: Supported by the Natural Science Foundation of Hubei Province in China (2001Abb0778), The Science and Technology Foundation for Wuhan Young Scholar (20015005039)biography: RAO Wen-bi (1967-), female, Ph. D, associate professor, research direction: artificial intelligence

关键词： RbFNN inteligent identification structural damage brower/Server (b/S) model