检索结果-南通市图书馆

Uniform decomposition of velocity gradient tensor

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2024年第1期36卷 24-34页

作者： Chenxi ma Chaoqun Liu Department of mathematics University of Texas at ArlingtonArlingtonTXUSA

in this paper,the principal decomposition of the velocity gradient tensor[∇v]is discussed in 3 cases based on the discriminant∆:∆0 with 3 distinct real eigen values,and∆=0 with 1 or 2 distinct real eigen *** velocity ... 详细信息

in this paper,the principal decomposition of the velocity gradient tensor[∇v]is discussed in 3 cases based on the discriminant∆:∆ith 1 real eigen value and a pair of conjugate complex eigen values,∆>0 with 3 distinct real eigen values,and∆=0 with 1 or 2 distinct real eigen *** velocity gradient tensor can also be classified as rotation point,which can be decomposed into three parts,i.e.,rotation[R],shear[S]and stretching/compression[SC],and non-rotation point,we defined a new resistance term[L],and the tensor can be decomposed into three parts,i.e.,resistance[L],shear[S]and stretching/compression[SC].Example matric are also displayed to demonstrate the new *** of principal decomposition between 3 different cases,and between Resistance and Liutex will also be discussed.

关键词： Velocity gradient Liutex resistance fluid kinematics

Unconfined compressive strength and failure behaviour of completely weathered granite from a fault zone

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2024年第6期21卷 2140-2158页

作者： DU Shaohua ma Jinyin ma Liyao ZHAO Yaqian School of Civil Engineering and Architecture Henan University of Science and TechnologyLuoyang 471023China School of Resources and Safety Engineering Central South UniversityChangsha 410083China China Railway 18th Bureau Group Co. LtdTianjin 300222 China China General Nuclear Power Corporation Shenzhen 518031China

Understanding the strength characteristics and deformation behaviour of the tunnel surrounding rock in a fault zone is significant for tunnel stability *** this study,a series of unconfined compression tests were conducted to investigate the mechanical characteristics and failure behaviour of completely weathered granite(CWG)from a fault zone,considering with height-diameter(h/d)ratio,dry densities(ρd)and moisture contents(ω).Based on the experimental results,a regression mathematical model of unconfined compressive strength(UCS)for CWG was developed using the Multiple Nonlinear Regression method(MNLR).The research results indicated that the UCS of the specimen with a h/d ratio of 0.6 decreased with the increase ofω.When the h/d ratio increased to 1.0,the UCS increasedωwith up to 10.5%and then ***ρd is conducive to the improvement of the UCS at anyω.The deformation and rupture process as well as final failure modes of the specimen are controlled by h/d ratio,ρd andω,and the h/d ratio is the dominant factor affecting the final failure mode,followed byωandρ*** specimens with different h/d ratio exhibited completely different fracture mode,i.e.,typical splitting failure(h/d=0.6)and shear failure(h/d=1.0).By comparing the experimental results,this regression model for predicting UCS is accurate and reliable,and the h/d ratio is the dominant factor affecting the UCS of CWG,followed byρd and thenω.These findings provide important references for maintenance of the tunnel crossing other fault fractured zones,especially at low confining pressure or unconfined condition.

关键词： Fault fracture zone Completely weathered granite(CWG) Unconfined compression strength(UCS) Multiple nonlinear regression model

Mitigate noisy data for smart ioT via gaN based machine unlearning

在线全文

学校读者我要写书评

暂无评论

Science China(information Sciences) 2024年第3期67卷 62-78页

作者： Zhuo ma Yilong YANG Yang LiU Xinjing LiU Jianfeng ma School of Cyber Engineering Xidian University State Key Laboratory of integrated Services Networks (iSN)

With the development of ioT applications, machine learning dramatically improves the utility of variable ioT systems such as autonomous driving. Although the pretrain-finetune framework can cope well with data heterogeneity in complex ioT scenarios, the data collected by sensors often contain unexpected noisy data, e.g., out-of-distribution(OOD) data, which leads to the reduced performance of fine-tuned models. To resolve the problem, this paper proposes Mu gaN, a method that can mitigate the side-effect of OOD data via the generative adversarial network(gaN)-based machine unlearning. Mu gaN follows a straightforward but effective idea to mitigate the performance loss caused by OOD data, i.e., “flashbacking” the model to the condition where OOD data are excluded from model training. To achieve the goal, we design an adversarial game, where a discriminator is trained to identify whether a sample belongs to the training set by observing the confidence score. Meanwhile, a generator(i.e., the target model) is updated to fool the discriminator into believing that the OOD data are not included in the training set but others do. The experimental results show that benefiting from the high unlearning rate(more than 90%) and retention rate(99%), Mu gaN succeeds in lowering the model performance degradation caused by OOD data from 5.88% to 0.8%.

关键词： machine unlearning generative adversarial network out of distribution data internet of Thing neural network

Effects of gravel on the water absorption characteristics and hydraulic parameters of stony soil

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Arid Land 2024年第7期16卷 895-909页

作者： ma Yan WANG Youqi ma Chengfeng YUAN Cheng BAi Yiru Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China Ningxia UniversityYinchuan 750021China School of Geography and Planning Ningxia UniversityYinchuan 750021China School of Ecology and Environment Ningxia UniversityYinchuan 750021China

The eastern foothills of the Helan Mountains in China are a typical mountainous region of soil and gravel,where gravel could affect the water movement process in the *** study focused on the effects of different gravel contents on the water absorption characteristics and hydraulic parameters of stony *** stony soil samples were collected from the eastern foothills of the Helan Mountains in April 2023 and used as the experimental materials to conduct a one-dimensional horizontal soil column absorption *** experimental groups with gravel contents of 0%,10%,20%,30%,40%,and 50%were established to determine the saturated hydraulic conductivity(K_(s)),saturated water content(θ_(s)),initial water content(θ_(i)),and retention water content(θ_(r)),and explore the changes in the wetting front depth and cumulative absorption volume during the absorption *** Philip model was used to fit the soil absorption process and determine the soil water absorption *** the length of the characteristic wetting front depth,shape coefficient,empirical parameter,inverse intake suction and soil water suction were derived from the van Genuchten ***,the hydraulic parameters mentioned above were used to fit the soil water characteristic curves,unsaturated hydraulic conductivity(K_(θ))and specific water capacity(C(h)).The results showed that the wetting front depth and cumulative absorption volume of each treatment gradually decreased with increasing gravel *** with control check treatment with gravel content of 0%,soil water absorption rates in the treatments with gravel contents of 10%,20%,30%,40%,and 50%decreased by 11.47%,17.97%,25.24%,29.83%,and 42.45%,*** the gravel content increased,inverse intake suction gradually increased,and shape coefficient,K_(s),θ_(s),andθ_(r)gradually *** the same soil water content,soil water suction and K_(θ)gradually decreased with increasing gravel *** the same soil water s

关键词： stony soil gravel content water absorption characteristics hydraulic parameters one-dimensional horizontal soil column absorption experiment van Genuchten model eastern foothills of Helan Mountains

The first record of a Konservat-Lagerstätten in which early post-settlement stages of fossil archaeobalanids(Cirripedia:Balanomorpha)are preserved

在线全文

学校读者我要写书评

暂无评论

integrative Zoology 2024年第2期19卷 200-223页

作者： Tomáš KOCÍ Rok gaŠPARiC John BUCKERiDGE martina KOCOVÁ VesELSKÁ Aleš ŠOSTER ivancická581 PragueCzech Republic Palaeontological Department Natural History MuseumNational MuseumPragueCzech Republic Oertijdmuseum Bosscheweg 80Boxtel5293 WBThe Netherlands institute for Palaeobiology and Evolution Novi TrgKamnikSlovenia Earth and Oceanic Systems Group RMIT UniversityMelbourneAustralia Museums Victoria CarltonVictoriaAustralia Department of Paleobiology and Paleoecology Institute of Geology of the Czech Academy of SciencesPragueCzech Republic institute of Geology and Palaeontology Charles UniversityPragueCzech Republic Faculty of Natural Sciences and Engineering University of LjubljanaLjubljanaSlovenia

A diverse sessile barnacle fauna from a Miocene shallow-water deposit at Dolnja Stara vas in Slovenia is *** includes the first descriptions of early post settlement juveniles of Actinobalanus sloveniensis attached to mangrove *** represent three distinct growth phases,the earliest being interpreted as being less than 24 h post settlement,the others being 1 to 2 days post *** assessment of their taphonomy is *** adult balanomorphs are attached to a variety of organic substrates,including mangrove leaves and branches,fragments of the conifers?Taxodioxylon,Carapoxylon,pine cones,molluscs,and cetacean *** barnacles include ***,Amphibalanus venustus,and Perforatus perforatus—many with opercula retained within the *** retains some of the original shell *** is the second record of barnacle–plant associations from the Central Paratethys from Kamnik and *** paleoecology and paleogeography of the site are discussed.

关键词： acorn barnacles barnacle metamorphosis epibiont paleoecology taxonomy

Provenance of Conglomerate and Sandstone from Early Permian Shoushangou Formation in Xi Ujimqin,inner Mongolia:implications for Understanding Paleo-Asian Ocean Subduction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2024年第1期98卷 10-31页

作者： ZHANG Yingli GUO Xianqing ma Shouxian MNR Key Laboratory of Metallogeny and Mineral Assessment Institute of Mineral ResourcesCAGSBeijing 100037China Chinese Academy of Geological Sciences Beijing 100037China

During the Late Carboniferous to Early Permian,a rift was formed by post-collisional extension after ocean closure or an island arc-related basin formed by Paleo-Asian Ocean(PAO)subduction in the Xi Ujimqin ***,the closure time of the PAO is still under ***,to identify the origin of the PAO,the geochemistry and U-Pb age of zircons were analyzed for the extra-large deep marine,polymict clastic boulders and sandstones in the Shoushangou Formation within the *** analyses revealed magmatic activity and tectonic *** conglomerates include megaclasts of granite(298.8±9.1 ma)and granodiorite porphyry(297.1±3.1 ma),which were deposited by muddy debris *** of this study demonstrated that the boulders of granitoids have the geochemistry of typical i-type granite,characterized by low Zr+Nb+Ce+Y and low ga/Al *** granitoid boulders were formed in island arc setting,indicating the presence of arc magmatism in the area that is composed of the Late Carboniferous to Early Permian subduction-related granitoid in southern Xi *** diagrams for determining sedimentary provenance using major and trace elements indicate that Shoushangou sediments originated from continental island arc-related felsic *** zircon U-Pb age cluster of 330–280 ma was obtained,indicating input from granite,ophiolite,Xilin Gol complex,and Carboniferous sources to the *** basin was geographically developed behind the arc during the Early Permian period because the outcropped intrusive rocks in the Late Carboniferous to Early Permian form a volcanic *** comprehensive analyses of source areas suggest that Shoushangou sediments developed in a backarc basin in response to the northward subduction of the *** backarc basin and intrusive rocks,in addition to previously published Late Carboniferous to Early Permian magmatic rocks of arc unit in Xilin Gol,confirm the presence of an Early Permian trencharc-basin system in the region,r

关键词： provenance analysis backarc basin Shoushangou Formation Early Permian Central Asian Orogenic Belt

Wearable multilead ECG sensing systems using on-skin stretchable and breathable dry adhesives

在线全文

学校读者我要写书评

暂无评论

Bio-Design and manufacturing 2024年第2期7卷 167-180页

作者： Yingxi Xie Longsheng Lu Wentao Wang Huan ma School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou 510641China College of Automotive and Mechanical Engineering Changsha University of Science and TechnologyChangsha 410114China Guangdong Cardiovascular institute Guangdong Provincial People’s HospitalGuangzhou 510080China

Electrocardiogram(ECG)monitoring is used to diagnose cardiovascular diseases,for which wearable electronics have attracted much attention due to their lightweight,comfort,and long-term *** study developed a wearablemultilead ECG sensing system with on-skin stretchable and conductive silver(Ag)-coated fiber/silicone(AgCF-S)dry *** and normal adhesion to pigskin(0.43 and 0.20 N/cm2,respectively)was optimized by the active control of fiber density and mixing ratio,resulting in close contact in the electrode–skin *** breathableAgCF-S dry electrodewas nonallergenic after continuous fit for 24 h and can be reused/cleaned(>100 times)without loss of *** AgCF encapsulated inside silicone elastomers was overlapped to construct a dynamic network under repeated stretching(10%strain)and bending(90°)deformations,enabling small intrinsic impedance(0.3,0.1 Hz)and contact impedance variation(0.7 k)in high-frequency vibration(70 Hz).All hard/soft modules of the multilead ECG system were integrated into lightweight clothing and equipped with wireless transmission for signal *** synchronous acquisition of i–iii,aVR,aVL,aVF,and V4 lead data,the multilead ECG sensing system was suitable for various scenarios,such as exercise,rest,and sleep,with extremely high signal-to-noise ratios.

关键词： Multilead electrocardiogram Dry electrodes Wearable electronics Wireless transmission

A review of vehicle detection methods based on computer vision

在线全文

学校读者我要写书评

暂无评论

Journal of Intelligent and Connected Vehicles

Journal of intelligent and Connected Vehicles 2024年第1期7卷 1-18页

作者： Changxi ma Fansong Xue School of Traffic and Transportation Lanzhou Jiaotong UniversityLanzhou 730070China Key Laboratory of Railway industry on Plateau Railway Transportation intelligent management and Control Lanzhou 730070China

With the increasing number of vehicles,there has been an unprecedented pressure on the operation and maintenance of intelligent transportation systems and transportation *** order to achieve faster and more accurate identification of traffic vehicles,computer vision and deep learning technology play a vital role and have made significant *** study summarizes the current research status,latest findings,and future development trends of traditional detection algorithms and deep learning-based detection *** the detection algorithms based on deep learning,this study focuses on the representative convolutional neural network ***,it examines the two-stage and one-stage detection algorithms,which have been extensively utilized in the field of intelligent transportation *** to traditional detection algorithms,deep learning-based detection algorithms can achieve higher accuracy and *** single-stage detection algorithm is more efficient for real-time detection,while the two-stage detection algorithm is more accurate than the single-stage detection *** the follow-up research,it is important to consider the balance between detection efficiency and detection ***,vehicle missed detection and false detection in complex scenes,such as bad weather and vehicle overlap,should be taken into *** will ensure better application of the research findings in engineering practice.

关键词： intelligent transportation system computer vision deep learning vehicle detection object detection algorithm

Night warming increases wheat yield by improving pre-anthesis plant growth and post-anthesis grain starch biosynthesis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of integrative Agriculture 2024年第2期23卷 536-550页

作者： Yonghui Fan Boya Qin Jinhao Yang Liangliang ma Guoji Cui Wei He Yu Tang Wenjing Zhang Shangyu ma Chuanxi ma Zhenglai Huang College of Agronomy Anhui Agricultural University/Key Laboratory of Wheat Biology and Genetic Improvement in South Yellow&Huai River ValleyMinistry of Agriculture and Rural AffairsHefei 230036China Xianyang Central Station for Agricultural Technology Extension Xianyang 712000China

Global climate change is characterized by asymmetric warming,i.e.,greater temperature increases in winter,spring,and nighttime than in summer,autumn,and *** experiments were conducted using four wheat cultivars,namely‘Yangmai 18’(YM18),‘Sumai 188’(SM188),‘Yannong 19’(YN19),and‘Annong 0711’(AN0711),in the two growing seasons of 2019-2020 and 2020-2021,with passive night warming during different periods in the early growth *** treatments were night warming during the tillering-jointing(NW_(T-J)),jointing-booting(NWJ-B),and booting-anthesis(NWB-A)stages,with ambient temperature(NN)as the *** effects of night warming during different stages on wheat yield formation were investigated by determining the characteristics of dry matter accumulation and translocation,as well as sucrose and starch accumulation in wheat *** wheat yields of all four cultivars were significantly higher in NW_(T-J)than in NN in the 2-year *** yield increases of semi-winter cultivars YN19 and AN0711 were greater than those of spring cultivars YM18 and *** NW_(T-J)increased wheat yield mainly by increasing the 1,000-grain weight and the number of fertile spikelets,and it increased dry matter accumulation in various organs of wheat at the anthesis and maturity stages by increasing the growth rate at the vegetative growth *** flag leaf and spike showed the largest increases in dry matter ***_(T-J)also increased the grain sucrose and starch contents in the early and middle grain-filling stages,promoting yield ***,night warming between the tillering and jointing stages increased the pre-anthesis growth rate,and thus,wheat dry matter production,which contributed to an increase in wheat yield.

关键词： wheat asymmetric warming dry matter accumulation and translocation starch yield